Abstract:

The scientific inspect testing technique wire ropes on line is a difficult problem that internal and external science technique do not have surmounted yet. With the development of the modern computer and the information technique, people have a platform for the solvable this difficult technical problem finally. 

This article proceeds from the importance of the wire ropes testing on line. Describing on this platform mainly a chi eve the basic principle, key technique, theoretical estimation of the active service wire ropes scientific tests on line and the real time. Quantitative results testing on line for laboratory

Keywords:

Online wire ropes inspect testing technique practice active service

Main Catalogue

1.      Background (Importance, Basic Principle and Research History)

2.      Constitution (Sensor, Processing Circuit Analysis Safe Ware Result estimation)

3.      Index (Aim of Inspect Testing)

4.      Results (Laboratory Data)

5.      Reference Literature

1. Background

(1) Origin

The coal mine and metallurgical mine took place the accident for lifting the broken wire in wire ropes. The reason is caused by internal wire rope. Such as corrosion and broken wire etc, flaw. That is unable discovery with the people’s naked eyes.

(2) Importance

The wire ropes are a flexible component part in extrusive application to the engineering. The wire rope is always key component; even more it is the lifeblood in operation. In order to ensure wire ropes for working in safety, reliability, higher efficiency, it is necessary for the operation condition of the wire rope (such as broken wire, abrasion, corrosion flaw and metal fatigue, remainder load-carrying ability, assurance coefficient etc.) to proceed testing. The traditional wire rope testing Method is artificial visual examination. This method is that the inspectors proceed to observe the active wire rope regularly. Adopt calipers measure the diameter of the wire rope, feel by hard or seek the flaw with naked eyes. Obviously, Artificial visual examination can only discover the bare outer part flaw (for example broken wire), regard to the internal flaw is powerless. It would not be examined about the lose sight of wire ropes (or wire ropes section) flaw with the naked eyes. And it would be influenced relatively large by artificial factor. The reliability of the testing results are poor. There fore, many usage departments for wire ropes adopt changing the wire ropes methods regularly: According to the rated service life for the wire ropes as certain their changing cycle. No matter how the practical condition is, all wire ropes carry out changes at maturity. Obviously this can bring some questions.  

So adopt instrument proceed testing especially quantitative nondestructive testing is very important. This importance express in the following three respects.

 ①    Make out from wire rope application safety

In the course of the application, the wire ropes can’t avoid to produce the flaw of metal fatigue and abrasion, corrosion, deformation, rupture etc. Thus lead to wire ropes intensity decrease. Even be destroyed suddenly. The wire ropes take place the destructive accident in application. The damage of equipment. The many accidents that the Casualties of the personnel. It was many accidents that the typical cases are reported publicly.

For example, the 12 persons were killed for ropeway-hauling rope was ruptured at Bedenmale, Switzerland in 1972. The 4 persons were killed for ropeway-hauling rope was ruptured at Begem, Norway in 1974. The 43 persons were killed for ropeway-hauling rope was ruptured at Kavale, Italy in 1976. The wire ropes of the suspension bridge were ruptured at Da County, Szechwan Province, China in 1986, caused the 31Casualties. A foreign ship was at anchor in Shanghai, China in 1987. It crashed on Baogang Transport Material Bridge Creation huge economical loss is caused by the fixed wire ropes rupture out of control. Climbing ropeway wire ropes ruptured at Tbilisi, former Soviet Union in 1990 caused the 55 casualties. In 1990, along-scale floating crane ship of Wu Chang shipyard lower floating dashed upon the NO4 bridge pier of Wu han Yang tze Bridge is caused by the fixed wire ropes ruptured out of control. Not only it bring about tremendous economic loss, but also bring about long-term hidden danger of local serious internal injury in bridge. These cases are too numerous to mention individually. It relates to many countries and almost all departments for the wire ropes application. There fore, the people attach great importance to the safety for the wire ropes in active service.

In order to take preventive measures. In view of application problems for wire ropes, many countries formulated the safety Regulations of the corresponding trade or the state detection standard early. But, why do the accidents being caused by the wire rope destroys take place for sometimes, impossible to defend effectively? It is the important reason that is short of the testing method and evaluation measure under reliable wire rope condition at present, yet. At over sea market, there have been formed many products of the wire ropes testing for recent years. But because of function wasn’t satisfied with meeting the requirement of worksite popularization application. Only a few important departments take them as the auxiliary testing tools proceeding the management and maintenance for the wire ropes. The more application departments for the wire ropes still adopt the methods of the artificial examination and the regular change. On the other hand because of the accuracy and reliability of existing testing instruments were not enough. Even if the departments that adopt the instrument testing wire ropes application, have taken place the accident, such as broken wire sometimes. At domestic manufacture, at present, the most application departments for wire ropes adopt the methods of the Artificial Visual Examination and the regular change. With the result that the accidents are happening with increasing frequency.

 ②    Make out from wire rope application economization

The wire ropes can always produce the whole piece of wire rope scrap for one local defeat. The Artificial Visual examination is limited in the attention concentration degree and experience of the inspector. Thus the artificial visual examination exists in the unreliability and the localization. On the other hand appear as the broken wire and the problems of unprecedented concentrated corrosion etc, in the wire ropes much more than anticipative cases for the change of the environment and condition of the wire rope, when the condition is serious, internal degraded wire ropes wouldn’t be discovered from their appearances at all. The regular change exists in blindness this way. There fore the Artificial Visual Examination and regular change the wire ropes. Not only it take place the danger of wire rope destruction potentially for the unreliability of testing, but also bring about enormous waste for unreason able change to cause wire rope scrap.  

In 1984, A statistical analysis made in USA of over 8,000 laboratory and field test records revealed some interesting facts on the condition of wire rope in services. The results make known that approximately 10 percent of all ropes considered showed a strength loss of over 15 percent. The strength loss of over 20% is more than the specified strength loss of 30%. That is to say, the wire ropes in services, approximately 10%, there are still potentially hazardous. More than 2 percent of the ropes had exceeded the specified strength over 30 percent wire ropes were in an extremely dangerous condition. On the other hand, more than 70 percent of all ropes in the sample were removed from service with little of no strength loss. According to Japanese statistical results also make known that more than 50 percent of all ropes in the sample were removed from service, the strength attaining over 90 percent of the new products, even than over 100 percent. Namely they are in running in the period of application. In 1985, according to the statistical results of China Coal Industry Ministry offered these numeral: If this instrument had been adopted for the wire ropes state to proceed with monitor, used suitable lip lubrication, (had been) saved, and (have been) saved the amount of the import wire rope foreign currency used from 20 percent to 30 percent.

③    The Maintenance for wire ropes

The mainest, the onerous work is the routine examination for the maintenance of the wire ropes in ordinary service time besides needing lubrication. In order to guarantee the safe operation for wire ropes, every wire ropes application units have formulated strict rules and regulations on the basis of corresponding trade safe norm and the state inspection standard. Demand practicing shift inspection, day inspection, and week inspection month inspection season inspection annual inspection and emphatically overhaul institution commonly. In the light of our country at present, above-mentioned institution implement is all major method with artificial visual examination. On account of the artificial visual examination is with the observation in the lead. The operating speed of the wire ropes can’t too fast in the course of the inspection. Demand under 0.3m/s commonly. But, the length of the wire ropes application in situ is hundreds meters long comely. Testing one time needs much time consequently. The inspectors are easy tired, the intension of labor is high and the efficiency is low. This is waste of much treasure time and has influence upon the heightening of labor force on the other hand; the artificial visual examination is required higher for the operators. It would be necessary to train such personnel for quite along time. The major problem is that this method can only check in slght of wire rope section with artificial visual examination. But some flaw is given up out of sight of the section and internal with in the wire ropes. It can’t practice the inspection of the whole course and completion. This become even more decrease its testing reliability. Thus, this is caused by wire ropes the accident occurs frequently. For example, Dukou Mineral affaire Bureau, Szechwan Province, China preceded the statistics analysis about transport ropeway accidents from 1970 to 1985. The results make clear that the wire rope accident is 90 times. It accounts for 16 percent of the accident sum total. It causes off the line 734 hours, 24 percent of off the line hours sum total. Shanghai Port Authority happens with in the machine damage accidents. Among them, about 33 percent is cause by the wire ropes accidents. When testing the instrument. Not only the wire ropes operating speed can heighten to several meter per second even teen meter per second, but also can achieve over all testing with whole course and there fore can ensure its safe operation, decrease the accidents, lighten the intensity of lab our, heighten the productivity.

As mentioned above, accidents occur frequently on account of the wire ropes testing measures can’t be proved effective thought practicing item-by-item sequential inspection of the wire ropes with much more energy and time. Even if apare no great expense practice change regularly. And make the user worrying about the safety degrees. This need to proceed suitable wire ropes in section and grant the popularization. The inspectors judge the remnant strength according to precise inspecting results. Under certain conditions measured this wire rope breaking pulling force. Master the real safe coefficient. Not only ensure safe operating but also determine changing date with this method. This would benift safe operating but also determine save the source and utilize the source effectively. In order to achieve this aspiration, the keys depend on the testing method of the wire rope flaw, analysis method and research and application for the instrument.

The wire ropes non-destructive testing and evaluation is that under the non-destructive wire rope use conditions, determine the wire rope state characteristic. With the certain testing technique and the analysis method. And evaluate their course according to the certain criterion. The inspector, detecting instrument and scrap standards are closed together relation. According to the testing of the wire ropes results, the inspectors determine the remaining service life of the wire ropes and scrap time with the inspectors experience know ledges for giving judgment upon the wire ropes. Among them. The testing results of the wire rope testing instrument is the most fundamental. Only when obtain the state of the wire rope damage flaw can evaluate the wire rope. There fore, as soon as the wire ropes create, the people begin to research the wire ropes testing problems. The wire rope non-destruction testing instruments have been gone out of the laboratory gradually during the past centennial research. Move toward engineering application and go further into a research that is combined with the engineering application problems. At present, on account of the continual progress of the wire ropes manufacturing technique and widespread application department, demand further research and developing the testing method and achieving technique for the wire ropes. This major express the following several aspects.

Firstly, the rope work wire without proceeding prestressingtorce processing. When the surface in the wire ropes happens to broken wire, thus reveal out of the wire ropes. This is the obvious, also the most original method—Artificial visual examination (foreign appellation is rag-and visual) produce correspondingly. The Artificial visual examination is proceeding like this: The inspector stands by the wire ropes and strokes them with cotton yarn in his (or her) hand. Testing speed operate for the wire ropes. If producing the yarn-drawing circumstances, the inspector stops the location to observe the broken wire carefully. However, with the development of the produce technique and material for the wire ropes, the rope work wire proceeded prestressing force processing. This makes the wire ropes to possess the astringency, without the bedding up words. And with the people research in a deep-going way for the geometrical structure parameter and the service life of the wire ropes, the structure of the wire ropes become mare and more complex, the flaw state of the wire ropes become to express more and more variety and complexity. The flaw testing difficulty increase continuously. For example, adopting magnetic focus technique testing the same diameter of wire ropes, Because of the fracture magnetic force line distributed and the fracture geometrical shape complexity, the signal-to-noise rato (SNR) to the reverse and the obverse twisting for the wire ropes are different greatly. The strong signal can be acquired in the obverse twisting, while the weak signal can be acquired in the reverse twisting. Even then it is submerged in the noise of ply waves. On the other hand, the surface of the wire rope forms the thicker fat lute for the wire rope testing.

Secondly, the diameter of the rope work wire in the wire ropes develop from single to various, from single-layer ply, from circular ply to triangle ply, and oval-shaped ply. There fore, the evaluation of the wire ropes flaw must be also change correspondingly. Take the wire ropes for example, in form wire ropes with the single diameter, can evaluate with broken wire numbers as the target to its intensity. But in the various diameter obvious. The influence of intensity is the different between the thin and thick of the broken wire. Under the circumstances, it is unreasonable that the wire ropes state evaluate with broken wire numbers as the target. Have to find the other target to wire rope state proceeding evaluation. Thirdly, the lift system of the wire ropes develops continuously substitute frictional lifter for cylindrical drum hoist more and more due to frictional lifter with the smooth advantage. The application condition of the wire ropes hare taken place greatly. The damage state followed also took place greatly. In the cylindrical drum hoist system, the wire rope express the bend fatigue broken wire, while in the frictional lifter, the wire ropes express the loss of the metallic efficient cross-sectional areas. Under the circumstances, the detecting installation with the major target for testing broken wire originally, must consider that how to achieve testing problems of the wire ropes loss.

Fourthly, with the source decrease increasingly on the surface of the earth recoverable reserves, the depth of mineral products exploitation increases continuously. The length of wire rope increase continuously, the diameter of wire rope enlarge continuously, the expenses of the whole wire rope also increase. This demand to enhance the safety testing of the wire ropes, heighten testing efficiency. External engineers experiment on the fatigue of large diameter wire ropes. There is evidence that the wire ropes is easier to occur in internal broken wire and earlier than external broken wire frequently. When finding the more external broken wire, this means that the wire ropes would be scrapped at once. Under the circumstances. Because of the visualization can do nothing about the internal broken wire of the wire ropes, it is important that the instrument inspect the wire ropes.

The fifthly, because of the tourism development, the ropeway develop rapidly in some touristy attraction. In order to heighten the ship passing through speed of the dike-dam, develop shipping trade important status in the communication and the requirement of the communication and transportation trade high-speed development, the number of the cable-stayed bridges and suspension bridges are much more and more. The wire ropes as building bridge major component safety of their application would be concerned the safety of the whole bridge. And because of cable rope out side cover in building bridge round the antiabrasion. Put forward a new requirement for testing: In the early part of the 20^th century, building bridges would be become the application late period in addition. The requirement to these bridges would be detected much more and more.

The sixthly, in generally speaking under all circumstances the wire ropes application, the produce and development of the wire ropes damage state is a slowly varying course. But in the course of practice application, discover the service life shorter, scrap frequently faster under certain circumstances. The scrap reason of wire ropes is caused by the parameter installation unreason-able of the whole lifting system in this circumstance. For example, purring the incline wire ropes hoist, if the intervals between the idler had not been adjusted inopportune, it would have been caused wire ropes resonance. To accelerate wire rope damage. There force, if the inspector can use instrument, taking change the wire rope testing results compare with the mystical testing results. If the inspector discovers the abnormal phenomena, remind the users for wire ropes testing lifting system function parameter to discover the problems and solve them, immediately. Thus, attain to lengthen the service objective life of the wire ropes. Adopt this measures is more effective than application later period with the instrument testing lengthen the service life of the wire ropes, and it is easier to attain scientific application and arrangement for the wire ropes.

3. The survey and the forecast for domestic and foreign. As mentioned before, the wire ropes, there occur testing problems form their birthday. After the research and development of a century, no matter where the testing principle of the technique achievement, the wire rope nondestructive testing research produce development by leaps and bounds. Table 1-1 shows that the methods and principles adopted once in the wire ropes non-destructive testing, among of them, some methods and principles have been obsolete for the difficulty in technique of principle. The following is that major introduce several testing methods that have been used in the engineering practice and are developed at present.

 (1)   The Research of the Testing Principle for Wire Ropes flaw states

The Research work of this section is the most active part in the wire ropes non-destructive testing, also is the keys part.

As one of the oldest methods, the magnetic non-destructive testing, it is also the earliest to apply in the wire rope testing. In 1906, the south Africa C. Mc Can R.colson developed together the first wire rope non-destructive testing installation is on the basis of elector electromagnetic magnetic principle. After undergoing the methods of Ac (alternating current excitation) and DC (direct current excitation), at the present time, the wire rope electromagnetic inspection installation become more and more tend to adopt the permanent magnet for wire rope the excitation. And technique maunders gradually. It is also one of the most widespread application methods at present. The famous company that produce the wire ropes, such as NDT Technology Inc, in USA, Meraster in Poland, their products are all on the basis of the electro magnetic inspection principle.

In the wire ropes flaw testing and diagnosing practice, according to the different nature and condition of the wire ropes flaws divide them into two large kinds: LF type (localized) and LMA type (loss of metallic area). The concrete character of the two flaws are as follows: LF type flaw (Localized Fault): in the local location of wire ropes produce damage that include internal and external broken wire, corrosion pots, local shape unusually. LMA type flaw (loss of metallic Area): produce the metallic cross-sectional areas in the wire ropes cross-sectional areas decreasing damage that include abrasion, corrosion, shrink of the wire ropes diameter etc. while correspond with LF type flaw, this kind of flaws change along radial direction in the wire ropes slowly in common. The major characteristic that adopt the wire ropes testing device of the permanent magnet excitation is that achieve LF testing passing though local leakage magnetic field after testing magnetization and that achieve LMA testing passing through measuring magnetic-flux change in magnetic circuit arrange sensitive element. Because of the location difference in magnetic circuit selected sensitive element, these testing devices would be divided LMA/LF circuit magnetic-flux testing method and LMA/LF major magnetic-flux testing method. In the wire ropes magnetic-flux testing method. Because of the excitation source and the wire ropes form close circuit, thus magnetization is easy relatively. The circuit magnetic-flux and the major magnetic-flux in the magnetic-flux testing methods refer to Fig1-1 pass through circuit magnetic-flux Φr in the excitation circuit. And the major magnetic-flux of entering wire. In the LMA/LF circuit magnetic flux testing, the wire ropes are magnetized deep and reach the saturation magnetization with the permanent magnet. Put the sensitive element between the wire ropes and the permanent magnet or at certain location in the circuit magnetic way, measure the magnetic flux that flow back permanent magnet from the wire ropes passing through the air internal. This magnetic flux is the wire ropes metallic volume function between two pole terminals. The inspector can measure indirectly wire ropes average metallic cross-sectional areas between excitation. In addition, in this testing method, arrange the other testing devices between two pole terminals on the neutral surface. Testing the LF signal. LMA/LF major magnetic-flux principle in that the wire rope are magnetized and reach to saturation magnetization. There is A concentric coil twining round the wire ropes.  (Caused by broken wire, abrasion, corrosion etc), can lead to change of the major magnetic flux in the wire ropes. After passing through the integrator alternate, the output of the integrator between the major magnetic flux change proportionally. There fore, only when measure the change of V1 cans you achieve the change measure of LMA.

At present, there two testing methods in LMA; Because of the bulky volume with the testing method of LMA/LF circuit magnetic-flux and radial direction resolving property is lower (51cm). This method has been obsolete gradually.  While because of the definition higher of radial direction (4cm) at testing LMA time with LMA/LF major magnetic-flux method. Part of LF flaws can also reflect and approach the wire ropes state evaluation from the perspective of great practical significant than the signal of LF is. The signal of LMA is greater especially; the split coil would be solved technically. And pass signal-processing circuit of designing structure unique; achieve the absolute magnitude measure of the wire ropes magnetic flux. Make the testing method of LMA/LF major magnetic-flux extensive application for the wire ropes in situ testing

Table 1-1 The Wire Rope Nom-destructive Testing Principle

In LF testing, at first, adopt the inductance coil testing leakage magnetic field in the wire ropes. But because the output signal in coil come under the influence of relative speed change between the wire ropes and the coils greatly. This testing method has been obsolete gradually. Because of the development of the semiconductor technique, Magnograph series sensors in Canada, at first, adopted hall device inspect the leakage magnetic-field and applied for a patent in the late seventies Canadian rotes co graph sensor adopted the fluxgate technique achieved the signal collection of the wire rope LF flaw for avoiding violate patent of Magnograph in the ignites. Domestic technique, middle China science and engineering university and Shanghai mercantile marine institute adopted the integrated hall device and the fluxgate achieved the signal attainments of LF flaw individually.

Whether the circuit magnetic-flux inspect or whether the major magnetic-flux of LMA/LF inspect, if you want to require the flaw information for the wire ropes, the wire ropes must pass through the sensor. This cause wire ropes whole course testing to be difficult to achieve. In order to solve this problem, in 1994, H.K wan and C.M Teller at American Southwest Research put forward a kind of new type wire ropes flaw testing sensor that is on the basis of Magnetostrictive effect (Magnetostrictive Sensor, Mss) The basic testing principles, as shown in Fig 1-2 (8)

Each sensor includes a permanent magnet and a inductance coil. The permanent magnet provides a biasing magnetic field to ensure the sensitivity of sensor and electric is the same with mechanical wave spread along the wire rope axial direction. After the launching coil is stimulated by the pulse signal with the Pulser, the joule effect productive wave would spread along the wire rope axial direction. When the mechanical wave pass through receiving coil, because of villain effect. If there occur flaw signal, receiving coil can accept the return waves of flaw signal. In this way can achieve the wire ropes flaw testing. Because of existing initiative testing method, the time is shorter. The effectiveness is higher. According to the two scholars tentative experiment, testing 100m length wirer ropes need only several seconds.

At present, have the major difficulty in the following two respects for this testing method:

(1)   The Difficulty in Physics Field,

Nowadays don’t make a deep research on the mechanical wave mechanization of Magnetostrictive effect creation and trans missive characteristic.

(2) The Difficulty in Technique

According to the tentative research results. It is very wide that the Magnetostrictive effect causes the signal frequency band from several KH2 to 1m. How to collect this signal is that practical application must be solved the problem. If the two tough jobs were broke, this would be had a great future testing method.

At abroad, the Acousto-ultrasonic method is being adopted to achieve for the wire rope state testing on line. Now (9.10.11.12) besides the magnetic testing method. The basic testing principle ad shown in Fig. 1-3

The method is development on the basis of the original sonic launch method. Lead the sonic into wire ropes with a group of transducer, couplant. The imitative sonic launching specific property transmits in the wire rope. The other group of, conplant collect the signal, after passing amplifier enter the threshold controller and then calculate the stress-wave factor (SWF). Because of comprehension with sonic launch and ultrasonic two methods. Not only can proceed to the flaw inspection, flaw imagery, and flaw characteristic, but also can evaluate the inherent function of the testing wire ropes online. Such as the fatigue loss, intensity, hardness etc, for wire ropes.

This method can have application in dynamic state wire rope testing. It overcomes that the sonic launching method can only have application in static state wire rope testing and catch the instantaneous signal of the broken wire breakage, without enough.

Above-mentioned methods have main application in the material function of wire rope testing. At present the all of the world, are proceed to research the geometrical deformation of wire ropes loose ply testing etc. German SPK Company try to adopt the CCD device testing the diameter of the wire ropes. For the change of the wire ropes. American adopt artificiality knock at the wire ropes with hammer in their hands to discover the loose ply flaw.

(2)   The Analysis Process for Wire Ropes flaw Signal

After the flaw signal of wire roper is colleted by the sensor with the certain principles and methods. The analysis process measure of signal is also very important. The simplest method is that to show the signal on the oscilloscope. But is can’t store to provide analysis application later. In order to over come this flaw, can adopt the notebook recording instrument or tape recording instrument. The wire rope testing instrument of earlier period adopted all these methods such as Magnograph and LMA series flaw detector. Up to the eighties, with the high-speed development of the computer technique and digital handling technique, the computerization and visualization of the testing instrument the came a development tendency. With the signal of the wire rope testing processing because of the signal of LMA and LF existing different testing principle and signal characteristic, the signal processing adopted the different technique. In 1978 at Poland, researcher carried out experiment research, adopt three testing circuit, to collect the signal of the wire rope cross0sectional area loss, and then after passing A/D transform, achieve the digitalization.

According to the establishing model calculate the cross-section of the wire rope loss and chi splay on the computer’s screen. First of all a chi eve the quantitative handling. The domestic technique, Middle China science and Engineering University achieved the quantitative testing of the wire rope broken wire numbers, in the eighties. With the adopting equally spaced interval sampling technique and differential super threshold algorithm. In 1995 Japanese scholar Koichi Hana Sake and Kazuhiko Tsukada introduced image formation technique into the signal handling of the wire ropes. At first achieved the visualized testing of parallel wire rope broken wire.

American, Doctor H.R. Weischedel combine with the worksite application condition to the signal testing of LMA. Testing the signal size of wire rope LMA within the speed limits has nothing to do with the operating speed for the wire ropes with designing the split coil and the electric circuit structure of the new and original structure. And adopt a certain calibrating pattern achieve the quantitative testing of LMA. In Poland, K,Zawada introduced the personal computer Memory Card Internatonal Association (PCMCIA) standard in to the manufacturing standard of the wire rope testing instrument. Because of the high reliability, antimagnetic, powerful applicability, provide a way for the wire ropes testing instrument toward engineering application. At present, in Poland, MD series wire rope inspection instrument inter face in Meraster Company, all adopted this standard.

(3) The standard of the Wire Ropes non-destructive Testing evaluation and the Instrument Testing

It includes the contents of the two sides, one is the testing signal evaluation, the other is that it evaluates the wire ropes states for the testing results; evaluation of the testing signal is also evaluation for the testing instrument. It includes the index of the instrument definition, quantitative definition, penetrating power; signal-to-noise rato of testing signal is lower. Can’t be quantitative testing ability. After leading to the computer technique, achieve the quantitative analysis and handling for the wire rope flaw signal. At present, because of the wire rope quantitative testing technique mature day by day, and the results of testing can be evaluated for the wire rope state. Because of the wirer rope state evaluation is major evaluating the intensity of the wire ropes. But existing testing instrument can’t test the intensity of the wire rope directly. Because of the results of testing are related to the scrap standard of the wire ropes frequently. It is often necessary to introduce the personal factor, to the wire rope inspector is familiar with the instrument function and applied state.

At present, the scrap standard of the wire ropes make on the basis of breaking stress for the wire ropes. But mechanical function research of the wire ropes express this method unreliability in resent years. There fore, according to the present scrap standard of the wire rope with the results of testing, evaluating method to the wire ropes state become more and more unreliable. American NDT Technology Company is on the basis of the wire rope inspecting installation of LMA-LF^TM type, combine with the worksite application condition in the installation and the Artificial visual examination results. Put forward now to evaluating the method of the wire ropes intensity.

American inspection and material Association worked out the Electromagnetic Examination Standard of Ferromagnetic material steel wire rope (E 1571-96) in 1997. this is symbolic of the testing and evaluation have enter a brand new stage for the wire rope.

2. The constitution for the wire ropes inspecting installation

According to the peculiarity in coalmine application, the basic principle of the testing wire ropes adopts the magnetic non-destructive testing method. There is inspecting sensor, signal preprocessor, analog digital converter, sampling controller, computer analysis handling system etc several main component parts in major inspecting installation. The basic block diagram as shown in Fig. 2-1

 Fig. 2-1a Wire Rope Flaw Testing System for Three Gorges Ship lift

The sensor adopts two different magnetic testing methods inspect the broken wire and the loss of the cross-sectional areas for the wire ropes. Among them, broken wire testing sensor would export two way-signals individually. The signal is alternating current signal. Connect alternating current signal amplifier. The sensor of the cross-sectional areas loss testing would export two way-signals individually. The signal is direct current signal. Connect direct current signal amplifier later, multiple-path different nature signals pass through A/D converter later with computer, proceed to proceeding to analyzing handling, controlling sensor signal sampling is sampling controller. According to the sensor relevant wire rope operating length send out sampling pulse, control to sample the output signals of the two sensors individually. Among them, interspaced of broken wire signal sampling is less than the signal of the diameter testing. While the signal of the diameter testing is less than testing signal of the cross-sectional areas loss. It is between from 1mm to 10mm in general.

The following is that introduce the testing system combining with the main technique difficult point.

(1)   Development of the sensor

①  The Magnetic problems for wire ropes

According to the knowable technique as analyzed before, adopt the magnetic testing method inspect the same time, with the development of the permanent magnet material, adopting the smallest volume permanent magnet can put forward very strong magnetic field to be satisfied with the necessity of wire rope magnetization. There fore, testing wire rope method become more and more tended to adopt the permanent magnet achieving wire rope magnetization. Fig. 2-2 is that adopt the magnetic circuit in the small diameter wire rope testing. Because of smaller diameter for wire rope, the magnetized volume is smaller, correspond entry. At the Sam time.

In order to ensure the wire ropes magnetic uniformity, take increasing pole terminal method between the wire ropes and the permanent magnet, on the other hard, can also adopt method to parallel with the multi-piece permanent magnet. Increase magnetic flux in the wire ropes; achieve the wire ropes magnetic requirement. In face, adopt circumferential single circuit axial magnetization for wire ropes. Because of each circumferential part for the wire ropes being different from the permanent distance, the magnetization for wire ropes is non-uniform. Near the permanent magnet parts magnetic field intensity is higher, on the opposite side parts magnetization degree is lower in general. In spite of the pole terminals were adopted, can decrease this non-uniformity in certain degree. With the enlargement of the wire rope diameter, the non-uniformity distributed of the magnetic field become more and more obvious under the extreme circumstances, near the permanent magnet parts can inspect the signal obviously. On the opposite side parts can’t inspect the signal. There fore, to large diameter wire rope magnetization can’t adopt single circuit exciting way, must adopt circumferential multi-circuit axial exciting magnetization way manly. Because of the nonlinearity and vector characteristic for magnetic field, the magnetic intensity in the wire ropes can’t increase after the multi-magnetic field superimposition. There fore, when designing magnetic circuit, must distribute magnetic circuit reasonably. Ensure the multi-circuit magnetic effect. In the initial stage of experiment, have application in double circuit for small diameter wire rope proceeding excitation in imitation of single circuit excitation way. With the result that instead of increasing, the broken wire of the wire ropes even decreasing. And the signal is instability. These phenomenon express the multi-circuit magnetization can’t design in the light of the single circuit magnetic way simply. This is conforming to the theoretical analysis as mentioned before. At present, the key problem is that find the reason that the magnetic line distribute the magnetic circuit aspect.

When analyzing to adopt double circuit magnetization, the magnetic line distribute as shown in Fig. 2-3 Because of existing the pole terminals, couple up magnetic line of up and down two magnetic circuit with the pole terminals, form the magnetic line of the certain direction concentrating pole terminals areas. It becomes a magnetic source that forms the magnetic line with armature closing up on the other end surface magnetic line. At the same time, in order to ensure the wire ropes magnetic uniformity. The volume of the pole terminals is larger generally. In this way, the pole terminals is magnetized by the permanent magnet providing a great deal magnetic power, not by the wire ropes. In order to achieve the multi-circuit magnetization it is impossible to increase (or decrease) the volume of the pole terminals between the wire ropes and the permanent magnet.

In order to test and verify the correctness of above-mentioned analysis, proceed with experiment.

1) At first, make an experiment on a 24mm diameter steel stick the experimental installation as shown in Fig. 2-4. At first, adopt single circuit excitation. Detecting magnetic induction intensity’s are all 0.48T in measure point A,B individually. And then add as shown in dotted line excitation circuit. The whole system forms a double circuit excitation structure. At that time, detecting magnetic induction intensities are 0.73T and 0.75T in measure point A,B individually. This express that increasing magnetic circuit can be heightened magnetic intensity in the magnetic stick. During proceeding with sensor structure design, it is impossible for us to adopt magnet adjoining steel stick structure way. There must be a distance between magnet and steel stick. In order to imitate this condition, at first as shown in Fig.

The magnetic circuit of active line. Add a 5mm thickness aluminum plate because of non-permeability magnetic material. At that time, detecting magnetic induction intensities are 0.69T and 0/74T. Obviously, it is unlike for you to imagine the magnetic induction intensities of A point is mare than B point, even if the magnetic inductor intensities of these two measure points are all decreased. After adding a aluminum plate in dotted line magnetic circuit, detecting magnetic induction intensities are 0.66T and 0.67T individually. Even if after adding the distance between magnet and steel stick, the magnetic intensity is decreasing. But it is still more power than single circuit magnetic intensity. In addition, increment of magnetic circuit they exist the nonlinearity and vector characteristic, we can find the change condition from the whole magnetic induction intensity of magnetic circuit measure point. This require us to design the magnetic circuit must pay attention to have a subtle difference between the magnetic circuit; otherwise it is easy to lead to magnetic circuit design failure.

2) In experiment 1, we consider only magnetic circuit symmetrical condition; consider the non-symmetry condition in the following. In the laboratory, make an experiment on a 90mm diameter steel stick. Experimental installation as show in Fig. 2-5. during the experiment, add the condition of magnetic circuit as show in order number, detect experimental data as show in table. After adding a 5mm thick ness aluminum plate in excitation circuit, detect experimental data as show in table2. 

Fig. 2-5 Φ80mm steel stick magnetic Experiment Installation

Make out from the experimental data of table 1 and table 2: To large diameter of steel stick, muti-circuit excitation can increase magnetic intensity obviously. Whether the wire ropes from above mentioned experimental scheme is employed or not, still test and verify with experiment. According to the above-mentioned structure design sensor make a magnetic intensive experiment or 52mm, 90mm diameter for the wire ropes. With the result that the magnetic intensity of the wire ropes testing. The above-mentioned experimental express that it is feasible to adopt the circumferential multi-circuit axial exciting magnetization.

②     The acquirement for broken wire signal of the wire ropes

1)      The difficult point for broken wire signal acquirement

The exciting installation magnetizes the wire rope to certain magnetic field intensity; adopt the permanent magnet as exciting source. Leakage magnetic testing installation inspects the broken wire producing diffusive leakage magnetic field. There are inductance coils, hall device, magneto sensitive transistor etc, application in the magneto sensitive testing sensor of this kind magnetic field testing.

When the induced coil test, induced output voltage changes with Cole scanning speed change. The temperature drift of magneto sensitive transistor effect is greater; there fore the hall device for Hall effect is more advance in testing this kind of magnetic field. The inspecting sensor is composed of exciting installation and leakage magnetic testing installation when testing the wire ropes, must consider the following three questions:

(a)      According to leakage magnetic field testing principle of the wire rope broken wire, can be knowable for the single piece of wire rope diameter is thicker in 6×7 structure wire rope. At that time, the broken wire signal is easy to obtain for the single piece of wire rope produce the leakage magnetic field growth. But according to the experiment, the distances between strand peak and strand wave is growth as the wire rope diameter increase. And the relative location between the wire rope strands is easy to become deformed, as the wire rope diameter increase. As a result cause that the broken wire signal is very easy to inundate with the strand wave signals. Fig. 2-6 is the strand wave signals of 6×7 structure wire ropes. In Fig. Section a and section is normal strand wave signal, section b is that the signal form with the wire rope ply strand and the distance growth between wire strands. Besides, there is a burr signal in the signal cu. This is formed with the leakage magnetic field between the wire ropes for the diameter of the wire ropes.

(b) In order to ensure no miss testing, must install multiple component along the wire rope circumference for the diameter of wire rope growth and the circumferential covering area limited of the single component installing component number can be calculated as follows.

wire rope length

Fig 2-6 Wire rope stock wave signal

 Where Sp is the perimeter of component arrangement ring,

      Ss is the circumferential covering length of the single component

      CINT[·] is round off number

According to the circumferential covering are length is 7mm, if the diameter of wire rope is 30mm, must arrange at least 14 components along circumferential direction can achieve no missing the testing. As that time adopted the single component handling, it was very complex.

(c) The wire rope fracture out diffusion leakage magnetic field intensity attenuate from fracture location out ward as space negative index. There fore, the magneto sensitive component can inspect the internal broken wire intensity very weak. On the other hand, the broken wire in inlayer produce the magnetic field to become weaker for outer wire rope screening effete.

 2)      Magnetic Focus Testing Technique

In accordance with the above-mentional character, the broken wire testing in view of the magnetic focus testing technique, inspect the leakage magnetic field in the different adecker wire rope broken wire creating leakage magnetic field. The magnetic focus testing principle is as shown in Fig. 2-7

 The magnetic focus ring of uniform-distillated circumference collects the Hall device making hall device detecting average magnetic field with in the following four points mainly:

(a) the magnetic focus ring adopt the high permeability materials manufacture, such as industrial clean iron, perm alloy. They collects weak magnetic field with the wire rope fracture creating out diffusion circumference, increase the testing sensitivity. The experience express, the sensitivity can heighten over 10 times as compared with single Hall device testing.

(b) In order to prevent from missing testing, it is necessary to arrange a great deal components along circumference usually for the single Hall device scanning areas are limited along wire rope circumferential coverage. This wand increases the complexity in detecting sensor and follow-up signal handling system. After adopting the magnetic focus ring, would enlarge the scanning range of single component. There fore, using few components such as two or four can be achieved the no missing testing for the leakage magnetic field.

(c) There occurs homogeneous influence in the magnetic focus ring toward magnetic field. There fore after adopting the magnetic focus ring, would homogenize the leakage magnetic field between the wires and strands in the wire ropes to heighten the sound-noise rate of the testing signal.

(d) Arrange the each magnetic focus ring with a piece of Hall deice, and a piece of Hall device deals with independent channel. Thus, can distinguish the broken wire in the different locating and layers. As shown in Fig. 2-8, adopt the above-mentional testing method detecting the output signal curve on the surface of wire rope and the certain channel in the internal core wire broken wire testing. In the Fig, a,b location is the signal curve of a piece of outer broken wire and a piece of internal broken wire individually.

③ The inspecting method for abrasion signal

Under the ordinary circumstances, the abrasion testing of the wire rope adopt the testing main magnetic-flux method. The testing component adopt testing coil unusually. This brings the two problems for wire rope testing in situ.

1) The trouble of the sensor installation is caused by the coil twining the wire rope.

2) The sensitivity of testing coil is relevant with the operating speed of wire rope relative to the coil. Adopting the Hall-device testing magnetic field possess the advantage without speed influence. And can acquire absolute magnitude for the magnetic field. But, when the Hall device was put in magnetic wire rope main magnetic circuit testing directly, the Hall device output signal the saturation wouldn’t be susceptible to the tiny change in magnetic field for the magnetic inductive intensity great (in general from 0.6T to 1.0T). for this reason, put forward utilizing the inspection principle for magnetic bridge circuit magnetic way, place the Hall device in magnetic bridge way, testing the tiny change for the magnetic inductive intensity in the balance point, (the magnetic inductive intensity is with in ±100mT in common) to ensure Hall device high sensitivity and linearity. The basic principle as shown in Fig. 2-9.

The main magnetic way and the bridge way combine action magnetizing the wire rope to reach the saturation degree. Because of the wire rope and the main magnetic way being symmetrical about magnetic bridge way, can’t consider the influence of leakage magnetic flux. According to kirchhoff principle for magnetic circuit. This is,

Φm=Φw+Φb     (2-2)

WhereΦb is the magnetic flux in the magnetic bridge circuit

Φb=BbSb   among them, BbSb are magnetic inductive intensity and cross-sectional areas in magnetic bridge way individually: Φm is the magnetic flux in the main magnetic way. Φm=BmSm among them, Bm, Sm are magnetic inductive intensity and cross-sectional areas in the wire rope, Φw=BwSw, among them, Bw,Sw are magnetic inductive intensity and cross-sectional areas. In the wire ropes, take above-equation substitute (1) after arrangement, obtain the equation we may write the equation.

Sw=(BmSm-BbSb)/Bw    （2-3）

Here, the magnetic inductive intensity Bw in the wire rope and the magnetic inductive intensity Bm in the main magnetic circuit are constant value near saturable magnetic degree. The cross-sectional areas for the main magnetic way Sm are decided by design. There fore, make out from the equation (2-3) the cross-sectional areas of the wire rope Sw and Bb related to linearity.

Under the ordinary circumstances, the wire rope is identical with magnetic field parameter in main magnetic circuit; through the magnetic flux in magnetic bridge circuit is zero. When the cross-stctional areas for the wire rope change, the balance of the whole magnetic circuit system is broken. The magnetic flux in the bridge way isn’t zero. After testing Bb, the cross-sectional areas Sw can be acquired from equation (2) calculation. The Fig. 2-10 Sw is given by the following. Technique.

Fig 2-14Software system diagram

 Adopt in this prinuple designed sensor collect abrasion signal curve of wire rope in the certain mine lifting wire rope

(2) The handling electric circuit for detection signal

① The pre-handling electric circuit for detection signal

The electric circuit principle is shown in Fig. 2-12, the electric circuit principle is shown in Fig.2-13 

The electric circuit is composed of the signal coupling, amplification, low-pass filtration and reshaping etc. link.

In order to restrain the work electrical power disturbance in worksite situ, the electrical power of signal handling installation adopt the supply power pattern with PC/DC second regulated power supply voltage stabilizer to heighten the sound-noise rate and stability of detection signal. The signal handling circuit possesses the function as follow.

1) Can pick up the weak signal that the testing component sends from the noise background, the sound-noise rate for testing signal is over 34dB.

2) Can handle the multichannel-testing signal, each handling channel for testing signal doesn’t disturb each other.

3) Every channel can adjust the zero drift of amplifier and the gain of the amplifier.

4) Can adjust pass band in wave filter.

③     Data sampling board Selection

The function of A/D trans form is that the sensor with pre-handle send the analogue signal changing the digital signal of available computer handling to achieve quantitative analysis of flaw providing foundation. When choosing A/D, must consider the precision and time of trans form, channel number etc. Here, after consideration every aspect factor, select the PCL-818C A/D board of Taiwan Yanhua company Products. The A/D board is on the basis of IBM PC/XT/AT or data sampling board with high-function multifunction in compatible machine. It is possessed of feature as follow.

1) Can select 16 channels single-ended or 8 channels double-ended

2) Analogue quantity input

The twelve-digit number A/D trans form precision adopt DMA when data Tran missive pattern of different amplificative gain, the single channel sampling frequency can use 40Khz.

3) The software programming can adjust the multiple of gain.

4) The software can install A/D quantity size

5) Provide trigger of the software, internal clock and outer A/D Tran missive pattern

Besides, the A/D board can connect the PCLD-8115 signal adjustable board with Yinhua company products. The signal adjustable board provides temperature compensation circuit can restrain temperature drift for signal influence

(3) The development of analysis software for signal quantity

.The software block diagram for the wire rope flaw quantitative analysis system is as shown in Fig. 2-14 parts of function brief introduction as follow.

Calibration ——testing for broken wire. Ascertain threshold value.

                         Achieve the quantitative analysis for wire rope broken wire.

Parameter installation——Provide different structure wire rope parameter and the

                                        Quantitative analysis required parameter.

Sampling on line——When the sensor moves along the wire rope, the optical code

                                Wheel sends the outer-triggered signal; take the signal of the sensor into the computer,

                                Achieve space sampling for the testing signal. Ensure the quantitative analysis.

Historical data——Proceed to analysis offline for sampling signal in the past

Historical result——Proceed to display again for analysis results in the past

Wave analysis——Proceed to wave display for sampling signal, under this state,

                              pushing the key F, can print the displaying wave.

Fig. 2-14 software system Block Diagram 

 ② The quantitative analysis for abrasion flaw

According to the magnetic bridge circuit testing principle, can know that the metallic cross-sectional areas for the wire rope Sw is   Sw=(BmSm-BbSb)/Bw, there fore, after the sensor inspect Bb, the cross-sectional areas of the wire rope Sw can be get from above equation.

The abrasion of the wire rope is corresponding with the change quantity of magnetic flux. In fact, it is absolute change in whole magnetic flux of magnetic circuit variance. With above theoretical analyses can know that it is relevant with in proportion between the abrasion quantity and signal amplitude of wire rope. In order to ensure the sensor in the course of practical testing, possess the testing areas as large as possible, for the component is liner with out put in ±100mT. At the sensor design stage, would ensure magnetic feature in the main magnetic circuit is consistent with magnetic feature in wire rope testing soon. This means that make the magnetic-flux near zero passing through balance magnetic circuit. The metallic cross-sectional areas of the wire rope change very great for the different structure and technology of wire rope. Proceed to influence very great for magnetic circuit feature of the whole testing installation. The testing result isn’t accurate. There fore, before testing the wire rope, must calibrate the sensor. Namely, put the new wire rope without abrasion, into the sensor. The type of this wire rope is consistent with the diameter, material etc. Of testing wire rope. During the operating course, unload change, stretcher strain deformation have influence on the cross-sectional areas of wire rope for the wire rope is a elastic component.

It is require that the testing installation must calibrate testing online. Developed inspection installation provides two different calibration methods to counter different application state. After the whole lifting system install adjusts, proceed to testing for new wire rope testing online. There fore, select at time, testing result is compared with the basis point to acquire the state of wire rope relative abrasion. In general speaking, adopt the preceding method is more accurate to acquire the abrasion state of the wire rope.

Besides, the abrasion testing of wire rope is to measure the absolute intensity of magnetic field in the magnetic circuit in fact. The measuring is each point abrasive size actually. The leakage magnetic field has great influence on testing result for the deformation and the broken wire. For this reason, must adopt the smoothing technique in software to decrease the influence of abrupt change leakage magnetic field. The Fig from 2-16 to 2-18 is the quantitative output results for abrasion testing.

③ The quantitative testing for rustiness

The rustiness for wire rope can be divided into two kind of pitting and corrosion. The rustiness leads to the decrees of the efficacious metallic cross-sectional areas. Not only breaking load would decrease, but also fatigue occurs untimely. Obvious for the fragility being coursed by stress crack. Rustiness can also decrease the elasticity for wire rope. At present, the quantitative evaluation for wire rope rustiness lacks the effective means. Here, we are on the basis of the basic principle for the wire rope magnetic testing, put forward adopting. Equivalent rusting concept to achieve rustiness quantitative evaluation. By the Equivalent Rusting Concept we mean proceeding from the wire rope intensity, analyze the different rustiness degrees have influence upon the wire rope intensity. To combine the magnetic testing result and give out a quantitative target, ascertain the application state for the wire rope. Make a analysis in the concrete, inspect out the pitting etc local flaw of wire rope with leakage magnetic field testing method. Taking their signal intensity and feature are compare with the broken wire signal, ascertain the wire rope concern between the pitting degree and broken wire number.

Adopt magnetic bridge circuit principle inspect out the corrosion etc, large areas flaw for the wire rope, ascertain after the rustiness, the efficacious metallic cross-sectional areas to combine the intensity theory and give out the practice load bearing cross-sectional areas.

 (4) The evaluation of testing results for wire rope state

The aim of wire rope testing is that not only obtains the geometric parameter of overall accuracy, but also provides the requisite parameter of wire rope intensity, lifetime evaluation, proceeding to provide the basis for practical wire rope change. There fore, it is necessary/reasonable that the testing result would enable to be connected with the requisite parameter for the wire rope evaluation. At present, evaluating wire rope state start with wire rope intensity respect in general. However, the difference of accepting force and scrap condition for wire rope are very great for the geometric shape complexity and the application condition change of the wire rope, thus, the evaluation of the wire rope intensity lack the parameter with instrument testing. The internal and external department concerned evaluates the wire rope major basis with wire rope testing result basically. And then combine with damaged experimental result of the wire rope. Here, we ascertain the wire rope state with the practical metallic loss as the major target. Here, by practical metallic loss is meant the loss of wire rope metallic function including the flaw of broken wire, abrasion, rustiness, fatigue etc. This loss is corresponding with the certain testing signal of the wire rope.

① Evaluation basis of non-destructive testing for wire ropes

It is known to all that the important feature for wire rope cant be disrupted suddenly. Because of the complexity for wire rope structure, it bears the combining action such as stretching, bending, squeezing, torsion, etc. in the course of manufacture. There fore, the wire rope bears force state very complex. Every piece of wire rope is composed with some dozen of wires. It is a statically indeterminate system many scholars desire to solve the each wire internal force with high order partial differential equation, precede to evaluate the operation life for wire rope. But, it is very different to use in concrete practice. They have many influence upon the operation life factor for wire rope such as stress (wire rope stress), in proportion as the diameter between wheel and wire structural form and material quality for the wire rope, twining technique, lubricating condition, environment temperature, glide wheel material quality, rope score shape of glide wheel. Etc. It is difficult for many factor to calculator the operation life with a formulation accurately. There fore, every country is grounded on experiments and industrial application experience to ensure selecting wire rope with enough statically intensity. This brings about many problems for the application safety of the wire ropes. There fore, the experimental research results for wire rope testing (destructive or non-destructive testing) pay an important part in the design, manufacture, application and maintenance.

1) Failure model for wire rope

The main destructive reason for wire ropes is divide into three kinds of corrosion, abrasion and fatigue. Because of the three factors common action result, the wire rope failure is none other than broken wire, broken strand and diameter shrink. Lead to decrease the intensity of the wire rope. At last reach the ultimate tensile strength and then destruction. In general speaking, after hanging a new wire rope. Soon, the structure of the wire rope becomes inseparable. The loads distribute even in the wire rope. At same time, counteract the internal stress between supporting force of wire ropes each other, increase the number of disruptive wire at the some time. As a result, increase the breaking pulling force, and then, the intensity of the breaking pulling force becomes low gradually. To the certain extent that the wire rope disrupt suddenly. According to analysis as mentioned before, combine with the practical application

State, adopt as shown in Fig. 2-19 model as the failure model for wire rope application.

2) The intensity analysis for wire rope

During the practical application course for wire rope, the research analysis of wire rope failure concerned express: with the increment of application time for stretching resistance strength of wire rope, produce the stretching resistance strength for wire rope decrease for the wire rope selection type consider the influence of the endurance

Bending strength and impact resistance load strength in the course of wire rope destruction. There fore, during the course of application, by the wire rope intensity mean the whole breaking pulley force for wire ropes. According to the intensity standard for the wire rope, the whole breaking pulling force for wire ropes Sb (Breaking Strength) are:

        Sb=KSa   (2-6)

Where, Sa (Aggregate Strength) is the whole wire aggregate breaking force in the wire ropes, K is the coefficient for wire ropes, the quantity (large or small) of value K come under the influence of the wire rope structure, lubricating condition and the influence of stress state in the wire rope.

The contact stress between wires in the wire rope can analyses on the basis of hertz (HZ) formula. Before the wire rope without bearing load, the contact relationship is shown in Fig. 2-20 (a). their contact area is zero. After pressure action, the contact position produce deformation as shown in Fig. 2-20 (b)

Fig. 2-20 The analysis schematic Diagram for wire stress

The contact line becomes the contact surface of rectangle, and the contact point becomes a ellipse (or circular) contact surface. Every point on the contact surface produce the contact stress according to certain regular distribution is relevant with deformation quantity. According to the research for elasticity mechanics, can know that the abrasion of wire rope don’t occur at that time, the contact stress increase between the wires. The axial component force of this stress. Counteract on the axial pulling force of wire rope. The result is that the whole rope breaking pulling force of wire rope is fewer than all wire aggregate breaking puling force in wire rope. When wire rope increment between the wires. The contact stress increase. It expresses the value K increment. These decreasing contact stress remedy the intensity for wire rope abrasion decrement. (Sw decrement). According to (2-6) equation, we know. The result is that the whole rope breaking pulling force of wire rope change isn’t great during the whole wire rope efficacious application term. But at the later period of application, because of Hertz (Hz) stress increment to about zero. At that time, value K is definite value. While Sa increase continuously, decreasing contact stress can’t neutralize the wire rope intensity loss of continuous increment. This causes the sudden failure of wire rope. Because of the complexity of pulling stress, bend stress, etc in the wire rope, it isn’t impossible that estimate or decide the contact stress for wire rope intensity influence. There fore, the non-destructive testing method can’t determine the breaking intensity for the whole rope of the wire rope. And as analysis before, we know that, the breaking intensity for the whole rope of the wire rope can’t explain the wire rope safety. So, must seek the parameter that can inspect and explaining wire rope safety.

3) The assessment target for the wire rope intensity loss

Let wire rope bearing load, is P, P can change under Pmax context. Let Sb is the breaking pulling force for the whole rope of the wire rope, Sb can change above Sbmin context. When the following equation is tenable, the wire rope can use safely.

              Pmax < Sbmin   (2-7)

As analysis before, we know, when the wire rope is a new one, because of the lubricating state and other state min the wire rope without damage, so that value K is the smallest Namely      Kmin = Knew

It follows from (2-6), we know that the loss of breaking strength for whole wire rope (LBS) is:

         LBS = Sbnew (1-Sb/Sbnew)

its percentage of the relative loss strength is:

           LBS% = LBS/Sbnew×100= (1-Sb/Sbnew)×100

The loss of aggregate strength (LAS) is:

           LAS = Sanew (1-Sa/Sanew)

its percentage of the relative loss strength is

           LAS% = LAS/Sanew×100 = (1-Sa/Sanew)×100

The action of scrap criterion for wire rope is that guarantee from sudden breaking before next testing. Suppose wire rope proceed with testing. According to equation (2-7), we obtain Pmax < Sbmin (i) = KminSa(i) = KnewSa(i) 

           LBS(i)%=[1-Sb(i)/Sbnew; So that

       LBSmax(i)%=[1-Sbmin(i)/Sbnew ]*100= [1-KminSa(i)/KnewSanew]*100=[1-Sa(i)/Sanew]*100=LAS%

^{Therefore, the greatest breaking pulling force loss or aggregate breaking pulling force loss for wire ropes can be used as the scrap standard for wire rope. This makes a great difference from the breaking pulling force in general significance. During the application of the wire rope, cuttiga section of wire rope makes an experiment on damage. Because of the possibility and conventionality of operation, cutting the section of wire rope can’t ensure on the location of the weakest part. It is very dangerous to judge the whole wire rope strength with this data. The above equation is on the basis of equation (2-7). Only when calculate the greatest magnitude of wire rope strength loss, can you evaluate the wire rope state. We know from equation (2-8) the greatest strength loss for the wire rope is, in the final analysis, loss for aggregate strength. The equation eliminate magnitude wire rope coefficient K. if made certain of breaking strength in every piece of wire, we should acquire the wire rope state.}

According to this target, if adopt the suitable testing instrument, should understand the damage state of wire rope in the cross-sectional area in detail and the location and number of damage distribute state in the whole wire rope testing. According to its concentrative degree, judge the efficacious cross-sectional area size at the weakest location in the whole length and reduce quantity on the location of wire rope.

② Evaluation of broken wire testing for wire ropes

1) The cause of broken wire produce

During the application for long time, the wire rope metallic fatigue is caused by the wire beardy again and again, extruding under the power pulling force. When the bending and extruding reach certain times, in addition abrasion, the wires would break when the number of breaking broken wire reach certain number, the wire rope scrap, would change a new rope. Broken wire occurs to the middle and later period for wire rope application.

The wire ropes for broken wire scrap possess the following feature:

(a) The operation life is shorter

(b) Under the general condition, the abrasion and rustiness are lighter.

(c) The wire rope scope of application is that position that by pass pulley or spool is acted by stretching load with broken wire as scrap standard wire rope mainly.

2) The influence of the broken wire for wire rope strength

After the wire rope occur to broken wire, would the cross-sectional area for wire rope decreasing. Make its pulling force reducing. The reducing number and broken wire amount are related to distribution. Experimental evidence: The reducing of breaking pulling force for wire rope is certain proportional to the broken wire rate within 30% broken wire rate. If the broken wires distribute the whole length, don’t concentrate within a length of lay, the influence is very small for whole rope breaking pulling force. There are great difference between dispersing every strands and concentrating a strand within a length of lay. Make out from table (2-4) (variety of experimental wire rope is 6×24. The broken wire method is artificial cutting on the new wire rope). If the broken wires concentrate in a strand, the pulling force reduction is more doubled and redoubled change than dispersing in every strand. The stipulations in every regulation allowable broken wire number refer to distribute within every strand of a length of lay. If the broken wires concentrate on a surface of a strand, broken wire allowable number would decrease about one half.

  Table 2-4 The broken wire and location for influence of breaking pulling force

Broken wire number	Broken wire location	Pulling force % Reducing Rate
14(about 14%)	Concentrate in a strand, on a surface	26.6
	Disperse within three length of lay	2.3
	Disperse on the same cross-section of wire rope in every stand	9.6
	Disperse within three length of lay	3.6
30(about 20%)	Concentrate in two strand, on a surface	42.2
	Disperse within three length of lay	5.0
	Disperse on the same cross-section of wire rope in every stand	21.6
	Disperse within three length of lay	3.7
42(about 30%)	Concentrate in two strand, on a surface	43.1
	Disperse within three length of lay	6.2
	Disperse on the same cross-section of wire rope in every stand disperse within three length of lay	27.5

Above-mentioned experiments are proceeding in the laboratory. Worksite practice proves that: During the operating of the wire rope. Not only occur to external broken wire but also does the internal broken wire. The distributing condition is different form the internal and external broken wire for the wire rope.

There is great difference between the two for the wire rope structure and operating condition are different. The whole rope abruption and dynamic-load impact experiment express that proceed the worksite scrap wire rope:

The scraping part in scraped wire rope such as abrasion and rustiness are lighter. The reduction of whole rope breaking pulling force is caused by the broken wire section decrement mainly. There fore, the percent broken wire section area plus within a length of ply of wire rope with its total section area proportion namely can look upon the percentage of strength decrement. This also proves evaluation formula correctness above-mentioned relative wire rope strength. The correct implication for the broken wire quantitative testing of the wire ropes would be that. Broken wire quantity isn’t broken wire number. The broken wire quantity is none other than the percent of the sum total for the different wire diameter broken wire sectional area within a length of lay. This implication is embodied in Hoisting machinery safety regulation (State Standard GB6067-85) clearly. This norm stipulat. When safe coefficient is fewer than six, the scrap broken wire number of wire rope is 10% of the sum of total. When safe coefficient is between six and seven, the scrap broken wire number is 12%. When safe coefficient is more than seven, the scrap broken wire number is 14%. In addition, the scrap broken wire calculate with thin wire entirely. A piece if thick wire in the wire rope is corresponding to 1.7 piece of thin wire. For example, 6×Fi(29)filled-system wire rope, when safe coefficient is more than 6, the scrap broken wire number of wire rope calculate according to the following method: 6 strand × (22 pieces of thick wires × 1.7+7 pieces of thin wire) × 12% ÷ 1.7 = 18 pieces of the wires  .

All these require us that must be considered with designing the sensor for broken wire testing for wire ropes and distinguishing the broken wire at that time.

3)      The evaluation of the broken wire testing result

The aim of non-destructive testing for wire rope isn’t only acquiring the result of broken wire testing. It is very important for testing result to evaluate wire rope state. In order-to provide scientific basis for the maintenance and reasonable change of wire rope. As analyzed before, we know that the percent of broken wire within unit length (refer to a length of lay in common) will influence the strength and operation life for the wire rope seriously. The less broken wire concentrating area the more strength influences degree. But make out from the practical condition, unbroken wire make broken wire under stress state for their occurring coulomb frictional force between each wires in the wire ropes.

The broken wire stress is on the basis of the certain regular distribution, in a section of area, reach normal value gradually. What is called broken wire efficacious length is the stress reaching normal value? Over efficacious length is considered that the stress value of wire rope is all the same to normal condition. The research for the broken wire efficacious length express, when lifting wire rope testing, we have a disregard for the load capacity of broken wire generally. In this way, don’t consider that the broken wire efficacious length to make the testing result towards safe.

The research express that, the prominent feature of un corroded and un abrasion wire rope is almost tensile strength without reduce. There is little difference between new and old wire rope breaking force, in many experimental result. Only when the individual sample fold wire rope is with other factor little influence, or individual wire exist as fatigue flaw can it make the breaking tore decrement. The breaking force for wire rope (or tensile strength) reducing value is also within 5%. There fore concentration breaking force the broken wire decreasing efficacious metallic cross-sectional areas mainly for the tensile strength reducing very little causes reducing. As a result, with the decrement of the efficacious metallic cross-sectional number, is corresponding with the concentration breaking torle-decreasing umber. However, the broken wire can’t produce in the same cross-sectional entirely. There fore, the sum of broken wire cross-sectional areas within a length of lay for wire ropes can consider the decrement value of wire rope efficacious cross-sectional areas. In this way, we can calculate wire rope strength loss on the basis of broken wire condition within the length of lay. If ignore tensile strength change of wire rope, the new wire rope is related to broken wire strength loss of wire rope by the following:

LAS%=F%  (2-9)

Where f% is loss coefficient of metallic cross-sectional areas, within length of lay. Namely, there occur percent of the whole wire rope cross-sectional areas within broken wire areas for length of lay. The wire rope made by twisting equal diameter wire, it is equal to the percent of length of lay broken wire.

Here, we consider that the broken wire state has influence on wire rope state within a length of lay mainly. After adopting non-destructive testing technique acquire the broken wire state on the every location of wire rope, combine with the length of wire rope diameter, length of lay, the diameter of wire and type etc, the structure feature and the historical condition of the wire rope, the experience of users. It is not difficult for us to give out the wire rope state, suitable main tenure method, next testing time and correct scraping time etc.

 ③Evaluation of abrasion for wire ropes

1/ The cause of abrasion production

When wire rope abrades in the operation, it get into touch with other object and relative motion to produce frictional force. Under the action of physics and chemistry., abrade the surface of the wire rope continuously. The abrasion is commonly recognized damage form for wire rope. Take petroleum industry for example, and according to investigation, it is abrasion that the oil use failure form mainly for wire rope. But up to now have had not a calculating method enabling to ascertain the abrasion degree for wire rope. At abroad, adopt the evaluation method for wire rope abrasion commonly: one is on the basis of testing the surface of the wire rope, the other is on the basis of the application namely, the product of bearing load for wire rope and operation stroke. The former carries with the artificial factor and evaluates the internal abrasion without method.

The latter is applied to small changes of wire rope load, but it is very difficult in fact.

2) The classification for wire rope abrasion

The abrasion of wire rope is divided into the outer abrasion and the internal abrasion and deformed abrasion. There are two kind of monocyclic abrasion and whole cyclic abrasion in typical outer abrasion. As shown in 2-21. this kind of abrasion produce the efficacious metallic cross-sectional areas decrement and is related to outer contact condition mainly. However, the effect of the deformation and internal abrasion on the metallic cross-sectional areas for wire rope isn’t great.

 The deformed abrasion is cause by the vibration and collision. There other object, the hoist lifting wire rope, hits produce the surface abrasion of wire rope such as wire rope of roller surface. After deformation and abrasion, the extents of wire become wide. The wire rope is easy to break, even if the cross-sectional areas of wire rope decrease smaller because of the hardened surface on the wire rope. During the course of wire rope application, the curvature radius of each wire can’t be all the same. There fore, each wire in the wire rope can produce action force each other and occur to slide, forming internal abrasion. The condition takes place in the wire rope of multistory structure. Because of the producing and development of the internal abrasion, deformation abrasion and rustiness at the same time, and the effect on the metallic cross-sectional areas for wire rope change isn’t great. It reflect feature in magnetic testing signal that isn’t obvious. There fore, it is more difficult for internal abrasion and deformation a bras into. Detect and evaluate, must combine with influeme of other factor. We will illustrate in the rustiness parts in detail. In the falling, first of all

Discuss outer abrasion state evaluation.

Monocyclic abrasion whole cyclic abrasion

Fig. 2-21 outer abrasion for wire rope

3) The effect of wire rope abrasion on strength

According to abrasion experimental result of wire rope, we know, as shown in Fig 2-22 under the condition of the wire rope along circumferential abrasion, before the wire rope break, many abraded wire ropes have broken, when abrasion strength decrease, the decrement rate of cross-sectional areas are near the strength reducing rate. But after the abrasion increase the strength reducing seems to rise. Under the local abrasion condition, after wire rope break, the decrement rate and strength-reducing rate are almost the same.

4) The evaluation of abrasion state for wire rope according to the effect of wire rope abrasion on strength, combine with equation (2-6). The evaluation of wire rope diameter, if the wire rope diameter changes make not much difference in every direction, can consider that is caused by the abrasion circumferential abrasion, if the wire rope diameter change value makes much difference in two-curtain direction. Can consider that monocyclic abrasion, according to above sectional analysis, we obtain.

LBS%max=LAS%=LMA%  (2-10)

Namely, the decrement quantity of wire rope cross-sectional areas is equal to the greatest loss for wire rope strength. The circumstance is more complex for the circum frenetically abrasion as show in Fig. 2-23. Take 6×7Fc structure wire rope of Cross-sectional areas loss3% for outer layer wire for example, in order to determine all wires concentrating breaking force in the wire rope, must consider that each strand superficial lager wire in the wire rope all show up the helix structure. Every superficial lager wire will all appear as shown in Fig. Location along wire rope axial length direction. To consider a range with a far fewer resemble length, all 36 pieces of superficial layer wires will have an effect on wire rope concentrating breaking force, but it is not the only one that is shown in Fig. Six pieces of wires.

This means that this kind of structure wire rope. At that time, the percent of wire rope concentrating breaking fore was none other than

LAS%=   6×6×30%/6×7 =25.7%  but, it was not LAS%= 6×30%/6×7 =4.3%

There fore, we introduce the concept of reservation strength (Sr)

The definition of reservation strength is the sum of all wire breaking force besides the superficial layer in every strand. According to this definition, for 6×7 FC structure, we have; Sr%=1/7=14% to wire rope strength state of circum frenetically abrasion we have a calculating formula in the following.

 (LBS%max) y2, (LAS%)y2, (LMA%)y2 refer to wire rope the greatest breaking force loss is caused by circumferential abrasion, wire rope concentrating breaking loss and metallic cross-sectional areas loss individually.

④Evaluation of rustiness for wire ropes

1/ The cause of rustiness production

  The wire ropes use in the open air commonly. The sun-scorched and rain-drenched can corrode the wire rope. The corrosion makes the damage to wire ropes very seriously especially under the odious circumstance of the harmful gas, seawater. The abraded surface of wire rope exists as difference of oxygen nelerocyclics. It makes the certain local metal on the surface of wire rope into positive pole, the other near local metal into negative pole. In this way, form mass mini type battery. Under the action of the mini type battery, the surface of wire becomes many circular corrodible pits and deepens gradually. These pits become the concentrating points of the stress, the source of the fatigue flaw. At the same time, the corrosion decreases the cross-sectional areas of wire rope and reduces the elasticity and capacity of bearing impact load. Lead to wire rope scrap at last. According to the introduction of material concerned, 70~80% scrap wire rope is caused by corrosion, as for the fatigue breaking of deserving move attention is only 10~15%, under the common condition, the operating life difference between the fat liquoring and without fat liquoring is one times. At present, the wire ropes operating life in the hoister is form 2 to 3 years in our country. The wire rope operating life in water-drenched serious mine reduce three months. Not only waste materials and staffs, increasing production lost. But also influence production, producing accident for the wire ropes change frequently.

The rustiness of wire rope is divided into the outer rustiness and the internal rustiness. At present, testing rustiness can only adopt the methods of visualization and percussion. The internal rustiness testing is more difficult than external rustiness testing commonly adopts the following methods: A. Try to twist off between the strands of wire rope B. whether the diameter of wire rope is uniform or not. For example, if apiece of wire rope is internal rustiness, the diameter of passing through the wheel parts is reducing, but not to passing parts become thick. C. Konck at the wire rope hearing testing with little hammer knocking. If hear the “click” sound, this means internal rustiness in the wire rope. D. Internal decrease between outer layer strands, happen to broken wire in concave location of wire rope strand, at the same time.

2/ The effect of rustiness on application function of wire ropes wire rope strength. It is far more than broken wire and abrasion. For example, mine owner shaft of Sanjialin, Zaozhuang County, in Shandong Province, it is neither broken wire nor wire rope diameter decrement. The wire rope strength reduces 22-27 percent. At present and later, when many mine change wire rope, both length of lay and whole rope broken wire aren’t more, at present, not to find suitable method to measure the rustiness degree with quantitative concept for the effect degree of rustiness on wire rope strength is far more complex and serious than broken wire and abrasion. In order to analyses convenience. The rustiness degree of wire ropes in table 2-5 is divided into four grades and briefly evaluates the effect on mechanical function.

Table 2-5 Grade of Rustiness

Rank	Surface Rustiness Degree for Wire Rope	Loss of Mechanical Function
Mila (I)	Wires change the oolour, lose sheen, exist at scale or rusty spot (appear to minikin black point on the surface of the wire rope)	Abort 10%
More serious (II)	There are scales or pits on the surface of wire ropes, but isn’t connected yet.	10~25%
Serious (III)	Existing rustiness flaw, the rusty spot become pits are connected and form rusty minikin ditch. Outer layer wire tottering.	25~40%
Dangerous (IV)	The rustiness areas are larger, the wire lose circle, the iron mold gnaw into 1/3~1/2 depth between strand wire	Over 40%
	Fig 2-23 6×7FC circumferential abrasion schematic Diagram for wire rope

We can make from above table, the Rank (I) belongs to the Mile Rustiness. The rustiness effect isn’t great, can scrap on the basis of other stipulation. The Rank (II) rustiness would be considered the effect of the rustiness. The Rank (III) rustiness is serious rustiness. When reach Rank (III), the application isn’t safe. While the Rank (IV) has been in the dangerous state.

3/ Evaluation of Rustiness

Take one thing with another, such as discovering rusty spot with LF, discovering the mild rustiness in advance, providing suitable protective method. The key is the quantity quantization of LF signal and LMA signal with LMA testing serious rustiness to prevent the accident happenstance.

The rusty damage isn’t also independent existence in productive practice. It is always related to the equipment condition of application department, natural circumstance, maintenance, and management. It produces with fatigue and abrasion at the same time. There fore, it bring very difficult to evaluate the rustiness. Here, we put forward a comprehensive LF, LMA signal feature, proceeding to evaluating method, for a wire rope state. First select a section on the wire rope on testing, proceed to calibrate the signal in the section of wire rope. Ascertain the base line of LF signal and LMA signal individually.

When there occur rustiness flaw in the wire rope, on the one hand, the magnetic function in every parts of the wire rope have taken place changes for rustiness degree isn’t uniform. This reflecting in LF signal is the increment of sudden changes. Back ground noise frequency with overlying signal increase. At that time, according to LF signal, distinguish broken wire decrement. But practical state that produce broken wire signal isn’t broken wire. There fore, we call it is equivalent broken wire fd. Distinguish software and equivalent broken wire number with broken wire quantity according to the broken wire evaluation formula. We have:

(LAS%)d=(f%)d   (2-12)

Where (LAS%)d refers to the concentrating strength loss for wire rope is caused by the equivalent broken wire.

(f%)d is the equivalent broken wire number for wire rope According to above-mentioned formula we can calculate the wire rope strength state with LF signal ascertainment.

On the other hand, production of rustiness makes the metallic cross-sectional areas for wire rope relative increment. The oxidation and vulcanization etc for wire rope make the overall magnetic inductivity decrement of LMA measured value. If we consider the complicacy of rustiness existing condition and abrasion, we adopt the evaluation formula of circumferential abrasion strength calculating strength loss is caused by the rustiness. Namely,

(LBS%max)dy=(LAS%)dy=  (LMA%)dy/Sdr% ×100   (2-13)

Where, (LBS%max)dy,(LAS%)dy,(LMA%)dy, refer to wire rope the greatest strength loss is caused by rustiness, wire rope concentrating strength loss and equivalent cross-sectional areas loss. After two aspects consider comprehensively, we obtain the wire rope strength loss is caused by the rustiness:

(LBS%max)x = (LBS%max)d + (LBS%max)dy   (2-14)

According to this formula, after acquiring the signal LF and LMA, pass through the evaluation. We can know that the wire rope strength loss by rustiness produces.

The main technical parameter

The diameter is tested: φ1.5~200mm

The relative speed of the sensor between the wire ropes 0.0~6.0m/s

Optimum speed: 0.3~1.5m/s

The interstices of the guide bush in the sensor between the wire ropes: optimum distance: 2~6

The detected capability broken wire flaw (LF):

Qualitative: The accurate rate of on the point of concentrated broken wire qualitative test: 99.99%

Quantitative: There is a permissible error of a piece of wire or a equivalence on the point of Concentrated broken wire number.

There are no errors the quantitative testing more than 100 times on the point of Concentrated broken wire number.

The accurate rate≥92%

The detected capability of the quantitative change rate of the metallic cross-sectional areas (LMA):

The repeatability allowable error of the testing sensitivity: ±0.055%

The allowable error of the testing accuracy rate indicated value: ±0.2%

The detected capability of the location (L):

The indicated value percent error of the testing length: ±0.3%

The electrical supply:

The supply electrical power for the computer batter 5V

The specifications in common use <10Kg

4. The Results of Laboratory

(1)   The Explanatory Notes of Technical Terms

The accurate judge rate for wire ropes refer to the quantitative testing instrument for wire rope inspect the accuracy for the broken wire number within its qualitative distinguishing scopes.

That is to say that the quantitative testing instrument distinguish the broken wire number to conform to practical broken wire number for wire rope degree.

The change testing accuracy for cross-sectional areas refer to the change quantity of testing signal for the wire rope is caused by the change of wire rope per unit areas.

(2)   The experimental results of broken wire and abrasion for wire rope

① Testing Method

Our designing sensors possess the function of integration with broken wire testing and cross-sectional areas testing. There fore, the broken wire experience and cross-sectional areas experience are synchronization. Whether or not it exist as broken wire with being tested wire rope magnetization, sensitive element testing leakage magnetic field in broken wire location of wire rope. Analyze the leakage magnetic field waves with computer and relative software. Go further and judge the broken wire number with photoelectric encoder ascertain relative the location of broken wire. Inspect the cross-sectional areas change for wire rope with magnetic flux change testing in wire rope. After calibration of wire rope cross-sectional areas, achieve cross-sectional areas for wire rope quantitative testing. At the some time, testing signal input computer analysis. After computer analyze, print the result (including the location of wire rope, broken wire number) checking with practical condition. According to above-mentioned condition, calculate broken wire quantitative accurate rate, differentiate error of broken wire location. According to after calibration sensor proceed to experience ascertain the abrasion quantity testing error range of cross-sectional areas for the wire rope.

② Testing Condition

First of all, is analogue of wire rope flaw state? Because of condition limit, we have only a piece of φ24(6×7)wire rope, sampling rope. Broken wire analogous state is shown in Fig. 4-1. Broken wire fracture interval of A and B place is 2mm. Broken wire state of location C is internal broken wire in Figure.1

Fig. 4-1 Analog broken wire schematic Diagram for Wire Rope

Because of the magnetic testing principle, cross-sectional areas change testing experience proceed in twice: Fix sensor in certain part of the wire rope, then increase the cross-sectional areas change of wire analogue wire rope between this part of strands for wire rope. According these experimental results, ascertain the testing sensitivity of the cross-sectional areas change. Increase the typical signal output waveforms of cross-sectional areas for wire analogue is shown in Fig. 4-2,

 

Fig 4-2 The signal output waves of cross-sectional areas change for wire rope

At first, there isn’t any wire in the wire rope in the course of experience for Figure (a), and then increase from 1.2. until 3 pieces of the wire rope. Finally, take any all 3 pieces of the wire ropes, the diameter of application wire rope is 4mm. In the course of Experience Figure (b) is at issue with Figure (a). The curve in the Figure according to the principle of the parts of second introduction, proceeding to calibration. Achieve the quantization.

2/ Take a certain length on the wire rope proceeding repeatability experience, to ascertain the error range of instrument.

④    Testing Results

1/ Testing results of broken wire for wire rope vide Table 4-1

2/ Handling results of data statistics for broken wire vide Table 4-2

3/ Handling results of data statistics for abrasion quality testing of cross-sectional areas vide Table 4-3

Table 4-1 Testing results of broken wire for wire rope

Order number	Situated L1		Situated L2		Order number	Situated L1		Situated L2
	Location (Meter)	Broken wire number (sticks of)	Location (Meter)	Broken wire number (sticks of )		Location (Meter)	Broken wire number (sticks of)	Location (Meter)	Broken wire number (sticks of)

Table 4-2 The statistics analysis results of the accurate judge rate for wire rope broken wire

Misjudge umber Practical number	-2	-1	0	1	2	Total
1		2	48			50
2		2	47	1		50
Total		4	95	1		100
Average(%)		4	95	1		100
Analyze calculating result expression: Occurring no misjudgment, broken wire quantitative accurate judgment rate is 95%. Occurring for allowable misjndgenent of a stick of wire rope, broken wire quantitative accurate judgment rate is 100%

Table 4-3 The testing results of cross-sectional areas change for wire rope

Order number	Segment L1 cross-sectional areas change (mm2)	L2 (mm2)	L3 (mm2)	L4 (mm2)	Order number	Segment L1 cross-sectional areas change (mm2)	L2 (mm2)	L3 (mm2)	L4 (mm2)
Analyze calculating result expression: Adopting this principle can achieve the testing error <±0.05%

5. Reference Literature:

(4) Yang Shuzi, Kang Yihua “Quantitative inspection for broken wires of wire ropes principle technique” Peking, National defense industrial publishing house.

(6) Chu JianXin. GuWei “The fluxgate testing method of leakage magnetic field for wire rope flaw”《instrument and apparatus Journal》 P437~P440, 18(4), 1997.

(7) GuWei, ChuJianXin “Testing sensor for a type of the fluxgate wire rope flaw” P226~234, 19(8), 1997