CN114720552A - Electromagnetic detection method for identifying defects of steel wire rope - Google Patents
Electromagnetic detection method for identifying defects of steel wire rope Download PDFInfo
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- CN114720552A CN114720552A CN202210318001.5A CN202210318001A CN114720552A CN 114720552 A CN114720552 A CN 114720552A CN 202210318001 A CN202210318001 A CN 202210318001A CN 114720552 A CN114720552 A CN 114720552A
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Abstract
The invention provides an electromagnetic detection method for identifying defects of a steel wire rope, which comprises the steps of carrying out deep saturation magnetization on the steel wire rope; amplifying and filtering the detected magnetic leakage signal and the magnetic flux signal; and detecting the damage degree of the local damage type defect and the metal cross-sectional area damage type defect in the steel wire rope. The invention has the beneficial effects that: the steel wire rope damage detection device has the advantages that two damage types and damage conditions of different positions of the steel wire rope can be effectively judged, the steel wire rope damage detection device is suitable for damage detection of steel wire ropes with different diameters, manual inspection is replaced, damage to the surface of the steel wire rope can be found in real time, the problems that manual inspection is low in efficiency, long in detection period and incapable of finding in time are solved, and the requirement for real-time performance can be met.
Description
Technical Field
The invention belongs to the technical field of steel wire rope detection, and relates to a steel wire rope electromagnetic detection method for detecting a steel wire rope through magnetic flux and magnetic leakage flux.
Background
The steel wire rope is widely applied to the fields of coal mines, metallurgy, traffic, petroleum and the like, the safety and the reliability of the steel wire rope in the using process are greatly influenced by the damage condition and the development trend in the using process, various damages of the steel wire rope are inevitable along with the lengthening of the using time, the performance of the steel wire rope is reduced, the normal and safe use of the steel wire rope is seriously influenced, and therefore the steel wire rope needs to be checked regularly.
At present, the defects of the steel wire rope are mainly detected by a traditional manual observation method in many occasions, and the safe work of the steel wire rope is ensured by a method of regularly and forcibly replacing the steel wire rope, but the manual observation detection method lacks scientific and accurate quantitative detection results as a judgment basis, so that potential safety hazards exist, and resource waste is brought.
The electromagnetic detection method can directly detect and evaluate the defect damage of the steel wire rope in service on the premise of not changing the state and the service performance of the steel wire rope, and further deduces the breaking force and the service life of the steel wire rope.
The defects of the steel wire rope are internationally classified into two categories: metal cross-sectional area Loss (LMA) type defects and Local Flat (LF) type defects, the LMA type defects mainly refer to that the metal cross-sectional area of the steel wire rope is generally reduced in a longer range, such as large-area metal Loss caused by abrasion, corrosion and the like or the diameter of the steel wire rope is reduced; the LF type defects mainly refer to discontinuous damage in the steel wire rope, such as wire breakage, pitting corrosion, deep steel wire rope abrasion and other local area damage.
The influence degree of various damage conditions and distribution along with the strength reduction of the steel wire rope is different, and the steel wire rope is usually scrapped because a certain section is seriously damaged, so that the timely and effective defect detection of the steel wire rope is very important.
Disclosure of Invention
The invention aims to provide an electromagnetic detection method for identifying defects of a steel wire rope, which solves the problem that the steel wire rope is damaged to different degrees due to the influence of different factors in the using process.
The invention relates to an electromagnetic detection method for identifying defects of a steel wire rope, which is realized by the following scheme:
the first step is as follows: the steel wire rope is subjected to deep saturation magnetization, a permanent magnet is selected as an excitation source for magnetization, and the magnetic induction intensity of the steel wire rope in a measured range is effectively increased by utilizing a multi-loop magnetization mode;
the second step is that: the magnetic flux leakage signal and the magnetic flux signal of the steel wire rope to be detected are amplified and filtered, so that the most obvious signal characteristics are conveniently given, the aim of computer identification can be achieved, and the detection precision is improved;
the third step: detecting local damage type defects in the steel wire rope, and judging the damage degree of the steel wire rope by using the detected leakage flux;
the fourth step: the method is used for detecting the metal cross-sectional area damage type defects in the steel wire rope, and on the basis of a loop magnetic flux measurement method, the magnitude of magnetic flux in the rope can reflect the magnitude of the damage degree linearly.
Furthermore, the deep saturation magnetization of the steel wire rope is caused by a magnetization aftereffect phenomenon, so that the magnetization degree of the steel wire rope is weakened, and the change of the magnetization state caused by the change of the metal cross-sectional area of the steel wire rope also influences the magnetic induction intensity in the steel wire rope, so that the detection precision is influenced.
Furthermore, the amplification processing means that the locally changed signals can be amplified in an alternating current manner, and the slowly changed signals are amplified in a direct current manner or modulated and demodulated.
Furthermore, the filtering processing refers to filtering processing on a spatial domain performed on the magnetic field signal, and filtering processing on a time domain performed on the magnetoelectric signal.
Furthermore, the loop magnetic flux measurement method is a method for indirectly calculating the magnetic flux in the steel wire rope by detecting with a hall element and measuring the magnetic flux in the air gap of the magnetizing loop.
Compared with the prior art, the invention adopting the technical scheme has the following technical effects:
1) the invention utilizes an electromagnetic detection method to effectively judge two damage types and damage conditions of different positions of the steel wire rope, and is suitable for detecting the damage of steel wire ropes with different diameters; 2) the method provided by the invention can replace manual inspection, can judge whether the appearance of the steel wire rope is abnormal or not, can discover damages such as wire breakage, abrasion and corrosion on the surface of the steel wire rope and damages such as wire breakage, fatigue and corrosion in the steel wire rope in real time, overcomes the problems of low efficiency, long detection period and incapability of timely discovering of manual inspection, and can meet the requirement of real-time property.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a block diagram of a broken wire magnetic flux leakage test;
FIG. 3 shows a step of measuring a metal cross-sectional area damage type defect of a steel wire rope;
FIG. 4 is a schematic diagram of a loop flux sensing method;
Detailed Description
To further clarify the objects and methods of the embodiments of the present invention, a more complete description of the embodiments of the invention is now provided in connection with the accompanying drawings.
The invention relates to an electromagnetic detection method for identifying defects of a steel wire rope, which comprises the following steps:
the first step is as follows: deeply saturated magnetization of the steel wire rope: in the electromagnetic detection process of the steel wire rope, magnetization is the first step for realizing detection, and the magnetization of the steel wire rope is realized by a magnetizer and mainly comprises a magnetic field source and a magnetic loop.
The permanent magnet is used as an excitation source, which is a magnetization mode without a power supply, and the permanent magnet adopts the rare earth permanent magnet with high magnetic energy product, because the rare earth permanent magnet has the advantages of high magnetic energy product, small volume, light weight, no need of the power supply and the like; after the diameter of the steel wire is increased, a multi-loop magnetization mode is adopted, so that the magnetic induction intensity of the steel wire rope in a measured range can be effectively increased.
The reasons why the steel cord must be saturated and magnetized in the first step are as follows:
in the steel wire rope in a loose state, a signal may be large during detection; the detection signal of the steel wire rope in a tensioned state is smaller at the fracture with the same size;
due to magnetic hysteresis, the magnetic induction intensity does not have single-value property before the magnetic field is not magnetized to a saturation state, and in this case, when the detection sensor scans the same fracture in the forward and reverse directions, detected signals are inconsistent;
in the detection process, according to the phenomenon of after effect of magnetization, when the steel wire rope moves faster, a magnetic field which is established in the steel wire rope by a local magnetic field provided by a magnetizer can be delayed, so that the magnetization is weakened, and the magnetic induction intensity in the steel wire rope can be influenced by the change of the magnetization state caused by the change of the metal cross section area of the steel wire rope, thereby influencing the detection precision.
The second step is that: the magnetic flux leakage signal and the magnetic flux signal of the steel wire rope to be detected are amplified and filtered, the most obvious signal characteristics are conveniently given, the aim of computer identification can be achieved, and the detection precision is improved.
Amplification treatment: when measuring the magnetic field, the output signal is generally weak and can be further processed after being amplified, when measuring the component of the magnetic flux leakage magnetic induction intensity along the magnetization direction, the electric signal is a unidirectional pulse signal superposed on the background signal, and the signal is not beyond a zero point; and when the component perpendicular to the magnetization direction is measured, the pulse signal with symmetrical zero-crossing points is obtained.
During measurement, when the movement speed of the probe relative to a measured magnetic field fluctuates, the signal waveform of an electric signal in a time domain changes, and when the movement speed is high, the central frequency of a signal generated by a fracture rises; at slow speed, the center frequency decreases.
In the process of detecting the electric signals, the locally changed signals can be amplified by alternating current, and low-frequency or direct-current components in the signals are eliminated by coupling or offset adjustment; the slowly changing signal needs to adopt a direct current amplification or modulation and demodulation technology, and the complexity of the circuit is increased by zero setting, temperature compensation and the like in the processing process.
The filtering of the signal is done from two sides: on one hand, the magnetic field signal is filtered, the signal works in a space domain, and a space filtering method is adopted; on the other hand, the method is used for filtering magnetoelectric signals, the signals work on a time domain, and a time domain filtering method is adopted.
Frequency component f of magnetic field signal in space domain when relative motion velocity v between probe and measured magnetic field is constant during detections(unit: m)-1) With frequency component f of the electrical signal in the time domainvThere is a correspondence between (unit: Hz) that f ist＝fsv; when the velocity v (t) varies, the frequency correspondence between the signals x(s), y (t) in the spatial domain and in the time domain is:
y(t)＝x(s)v(t)
F[y(t)]＝F[x(s)]·F[v(t)]
the filtering processes in the time domain and the spatial domain correspond to each other for a constant time-invariant field and can be implemented alternatively.
The third step: detection of local damage type defects: as shown in fig. 2, when a wire breakage occurs in a steel wire rope, a wire breakage signal is extracted by the magnetic flux leakage detection device, a signal model is obtained after a signal processing link, and then the detection signal is calibrated and inverted to determine a wire breakage state.
From the perspective of the detection process, the problem of the first aspect is mainly to solve a forward problem, namely that the known broken wire including position, size, geometric shape, etc. solves the leakage magnetic field signal and the signal representation form after the probe transformation, and from the detection point of view, the problem of distortion in the signal transformation process is solved, namely the aspect of the detection device is related; the problem of the second aspect is mainly solved by a type of inverse problem, namely, knowing a detection signal and an expression form thereof, and solving the broken wire condition, including position, size, geometric shape and the like.
The fourth step: detection of metal cross-sectional area loss type defects: the metal cross-sectional area of the steel wire rope refers to the sum of the cross-sectional areas of the steel wire ropes in the rope, and the defects on the steel wire rope, including wire breakage, loss, corrosion, diameter reduction and the like, can generate the loss of the total amount of the metal cross-sectional area, so that the strength of the steel wire rope and the safety coefficient of the steel wire rope in service can be directly influenced, the detection of the metal cross-sectional area of the steel wire rope is mainly realized by measuring the magnitude of magnetic flux in the rope, and the corresponding change of the metal cross-sectional area of the steel wire rope is reflected to the magnetic flux linearly.
When the steel wire rope is deeply saturated and magnetized, the axial magnetic flux of the steel wire rope is approximately proportional to the cross section area of metal, and the implementation steps are shown in figure 3.
According to different magnetic flux measuring methods, a loop magnetic flux measuring method is adopted, a Hall element is used for detection, the magnetic flux in the air gap of the magnetizing loop is measured, and then the magnetic flux in the steel wire rope is indirectly calculated, and a typical measuring principle is shown in figure 4.
The Hall element works based on the Hall effect principle, the size of an absolute magnetic field is measured, the sensitivity, the spatial resolution and the coverage range of the Hall element are determined by the geometric dimension, the shape and the crystal property of a sensitive area of the Hall element, the Hall element has the characteristics of good stability and good temperature characteristic, and meanwhile, the conversion of a magnetoelectric signal can be completed through the combination of the Hall element and a linear integrated circuit, so that an analog signal is converted into an electric signal.
The described embodiments of the invention are only some, but not all, embodiments of the invention; various modifications and alterations to this invention will become apparent to those skilled in the art; any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. An electromagnetic detection method for identifying defects of a steel wire rope is characterized by comprising the following steps: the method comprises the following steps:
the first step is as follows: the steel wire rope is subjected to deep saturation magnetization, a permanent magnet is selected as an excitation source for magnetization, and the magnetic induction intensity of the steel wire rope in a measured range is effectively increased by utilizing a multi-loop magnetization mode;
the second step is that: the magnetic flux leakage signal and the magnetic flux signal of the steel wire rope to be detected are amplified and filtered, so that the most obvious signal characteristics are conveniently given, the aim of computer identification can be fulfilled, and the detection precision is improved;
the third step: detecting local damage type defects of the steel wire rope, and judging the damage degree of the steel wire rope by using the detected leakage flux;
the fourth step: by utilizing a loop magnetic flux measurement method, the metal cross-sectional area damage type defect in the steel wire rope is detected, and the magnitude of the magnetic flux in the rope can reflect the magnitude of the damage degree linearly.
2. The electromagnetic detection method for identifying the defects of the steel wire rope according to claim 1, characterized in that: the adopted magnetization mode is deep saturation magnetization.
3. The electromagnetic detection method for identifying the defects of the steel wire rope according to claim 1, characterized in that: the signals which are locally changed in the amplification processing part can adopt an alternating current amplification mode, and the signals which are slowly changed adopt a direct current amplification or modulation and demodulation technology.
4. An electromagnetic detection method for identifying defects of a steel wire rope according to claim 1, characterized in that: in the process of filtering the signals, the magnetic field signals are filtered in a spatial domain, and the magnetoelectric signals are filtered in a time domain.
5. An electromagnetic detection method for identifying defects of a steel wire rope according to claim 1, characterized in that: a loop magnetic flux measurement method is used for detecting the metal cross-sectional area damage type defects.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117576635A (en) * | 2024-01-17 | 2024-02-20 | 中国石油集团川庆钻探工程有限公司 | Method for judging linear target tensioning state in video identification |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117576635A (en) * | 2024-01-17 | 2024-02-20 | 中国石油集团川庆钻探工程有限公司 | Method for judging linear target tensioning state in video identification |
| CN117576635B (en) * | 2024-01-17 | 2024-03-29 | 中国石油集团川庆钻探工程有限公司 | Method for judging linear target tensioning state in video identification |
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