阅读说明：本技术 一种钢丝绳涡流热成像缺陷检测方法及装置 (Method and device for detecting eddy current thermal imaging defects of steel wire rope ) 是由 杨炳坤 于 2020-07-10 设计创作，主要内容包括：本发明公开了一种钢丝绳涡流热成像缺陷检测方法及装置,涉及钢丝绳无损检测技术领域,提出的钢丝绳涡流热成像缺陷检测装置,基于涡流热成像法进行钢丝绳的热成像,响应速度快,可以对快速运动的钢丝绳进行在线检测；在获取钢丝绳的热图像数据时,不用与钢丝绳接触,无需耦合剂,受外来因素的影响很小；传统的钢丝绳检测难以准确的判断缺陷形位信息,本方案通过钢丝绳温度分布模型图能够准确的表征缺陷部位的形状信息和位置信息。(The invention discloses a method and a device for detecting eddy current thermal imaging defects of a steel wire rope, which relate to the technical field of nondestructive detection of the steel wire rope, and the eddy current thermal imaging defect detection device of the steel wire rope is used for carrying out thermal imaging on the steel wire rope based on an eddy current thermal imaging method, has high response speed and can carry out online detection on the steel wire rope which moves rapidly; when the thermal image data of the steel wire rope is acquired, the steel wire rope is not required to be contacted with a coupling agent, and the influence of external factors is small; the defect shape and position information is difficult to accurately judge in the traditional steel wire rope detection, and the shape information and the position information of the defect part can be accurately represented through a steel wire rope temperature distribution model diagram.)

1. A steel wire rope eddy current thermal imaging defect detection method is characterized by comprising the following steps:

using a known defect-free steel wire rope as a reference steel wire rope, and acquiring a plurality of reference thermal image data on the circumference of the steel wire rope by an eddy current thermal imaging method;

processing the reference thermal image data to obtain a reference steel wire rope temperature distribution model diagram;

detecting the motion position information data of the steel wire rope to be detected in the process of dragging the steel wire rope to be detected to move, and simultaneously acquiring a plurality of thermal image data to be detected on the circumference of the steel wire rope to be detected by an eddy current thermal imaging method;

processing the thermal image data to be detected in the same way as the reference thermal image data to obtain a temperature distribution model diagram of the steel wire rope to be detected;

and comparing the temperature distribution model diagram of the steel wire rope to be detected with the temperature distribution model diagram of the reference steel wire rope, finding out a defect part in the temperature distribution model diagram of the steel wire rope to be detected, and calibrating the position of the defect part according to the motion position information data to finish the defect detection of the steel wire rope to be detected.

2. The eddy current thermal imaging flaw detection method for the steel wire rope according to claim 1, wherein the process of processing the thermal image data comprises the following steps:

s1, carrying out image splicing and correction processing on a plurality of thermal image data of the circumferential section at the same position of the steel wire rope to obtain a steel wire rope temperature distribution model diagram I;

s2, setting a temperature threshold value, and removing image points lower than the temperature threshold value in the steel wire rope temperature distribution model diagram I to obtain a steel wire rope temperature distribution model diagram II;

s3, performing boundary repairing treatment on the steel wire rope temperature distribution model diagram II to obtain a steel wire rope temperature distribution model diagram III;

s4, extracting the contour of the steel wire rope temperature distribution model diagram III by using a contour extraction algorithm, obtaining a regularly distributed temperature field on the surface of the steel wire rope, and constructing to obtain a final steel wire rope temperature distribution model diagram.

3. The eddy current thermal imaging defect detection method for steel wire ropes according to claim 2, wherein in the step S3, the boundary repair comprises an opening operation and a closing operation.

4. The eddy current thermal imaging defect detection method for the steel wire rope according to claim 1, wherein in the process of finding out the defect part by comparison, a comparison difference threshold value is set, the temperature distribution model diagram of the steel wire rope to be detected is compared with a reference temperature distribution model diagram of the steel wire rope to obtain a comparison difference value, and in the temperature distribution model diagram of the steel wire rope to be detected, the part corresponding to the comparison difference value higher than the comparison difference threshold value is determined as the defect part.

5. The utility model provides a wire rope vortex thermal imaging defect detecting device which characterized in that includes:

the thermal infrared imager circumferential array is used for acquiring thermal image data on the circumference of the steel wire rope;

the position detection module is used for acquiring the motion position information data of the steel wire rope;

the high-frequency alternating current heater is used for heating the part of the steel wire rope, which needs to be imaged;

and the data processing terminal is used for processing the thermal image data, finding out the defective part and calibrating the position of the defective part according to the motion position information data.

6. The steel wire rope eddy current thermal imaging defect detection device according to claim 5, wherein the thermal infrared imager circumferential array comprises three high-frequency thermal infrared imagers, and when thermal image data on the steel wire rope circumference are acquired, the three high-frequency thermal infrared imagers are uniformly circumferentially arranged at 120 ° intervals around the steel wire rope.

7. The eddy current thermal imaging defect detection device for the steel wire rope according to claim 5, wherein the position detection module comprises an encoding wheel and a position signal processing module; the coding wheel is used for contacting with the steel wire rope and synchronously moving, and outputting a pulse signal representing the movement position of the steel wire rope to the position signal processing module; and the position signal processing module is used for receiving the pulse signal and converting the pulse signal into the motion position information data.

8. The eddy current thermal imaging defect detection device for the steel wire rope according to claim 7, wherein the encoding wheel rotates under the driving of the steel wire rope, and a pulse signal is sent to the position signal processing module once every time the encoding wheel rotates once.

9. The eddy current thermal imaging flaw detection device for steel wire ropes according to claim 8, further comprising a steel wire rope guide system for guiding the steel wire ropes to move linearly during the process of drawing the steel wire ropes by the drawing device, wherein the encoding wheel is installed at a position close to the steel wire rope guide system.

10. The device for detecting the eddy current thermal imaging defects of the steel wire rope according to claim 5, wherein the high-frequency alternating-current heater is provided with an alternating-current heater water cooling device, and the alternating-current heater water cooling device is used for cooling and protecting an excitation coil and an excitation source of the high-frequency alternating-current heater.

Technical Field

The invention relates to the technical field of nondestructive testing of steel wire ropes, in particular to a method and a device for detecting eddy current thermal imaging defects of steel wire ropes.

Background

The steel wire rope is a steel wire bundle which is formed by spirally twisting steel wires with similar mechanical properties and geometric dimensions according to certain specification requirements, and comprises the steel wires, a rope core, lubricating grease and the like. The special structure of the steel wire rope enables the steel wire rope to have the advantages of good flexibility, high strength, light dead weight, large elasticity, stable and reliable work, strong loading capacity and the like, and is widely applied to heavy-load traction occasions such as hoisting equipment, mechanical transmission devices, bridge machinery, ship mechanisms, crane cranes, cable car ropeways and the like. Therefore, steel wire ropes play an important role in national production.

Most of steel wire ropes are easy to generate the defects of fatigue, corrosion, pitting corrosion, abrasion and the like because of working in oil stain and high-load environments for a long time, so that the effective load capacity of the steel wire ropes is influenced, even the steel wire ropes can be suddenly broken, and serious equipment threats and life safety accidents are caused. Regular detection of the steel wire rope can ensure normal operation of the steel wire rope, assist maintenance work of the steel wire rope, reduce the probability of accidents caused by failure of the steel wire rope, and avoid great waste caused by mistaken replacement of the steel wire rope in a good working state. Therefore, it is very important to formulate a reasonable and effective nondestructive testing means for the steel wire rope.

The nondestructive detection of the steel wire rope has the characteristics of large detection batch, high repeatability and the like. The existing steel wire rope detection methods mainly comprise magnetic flux leakage detection, ultrasonic detection, eddy current detection, ray detection, optical detection and the like. The magnetic flux leakage detection identifies the defects by measuring the magnetic flux disturbed by the defects, has high detection speed and can capture the disturbance condition of the internal defects; the ultrasonic detection realizes detection by receiving a vibration signal returned by the defect, and can also realize the calibration of the internal defect; eddy current inspection is implemented by using a sensor to identify the eddy current distribution disturbed by a defect. The corresponding speed is higher; the X-ray detection utilizes X-rays, and the defects are identified through the picture on the other surface, so that the imaging is visual; and optical detection is carried out by directly shooting the surface of the steel wire rope through a camera, so that a higher detection result can be obtained.

The above mentioned detection methods have their advantages, but there are also many problems:

although the magnetic flux leakage detection is high in detection speed, the defect position and the geometric dimension are difficult to calibrate through signals, and the signal interpretation is not unique; the ultrasonic detection has low signal-to-noise ratio of echo signals and difficult defect identification due to the complex structure of the steel wire rope; the sensor for eddy current detection has a complex structure and low resolution for detecting defects such as broken wires, corrosion and the like; the ray method is visual but cannot carry out continuous detection, and the efficiency is low; although the optical method has high detection precision, the detection equipment has high cost and is greatly influenced by oil stains on the surface of the steel wire rope. Therefore, in order to meet the industrial requirement of high efficiency and high speed of modern steel wire rope detection, the invention provides a steel wire rope detection device based on an image recognition technology and an eddy current thermal imaging detection technology, and the steel wire rope detection device has great scientific research significance and practical value.

Disclosure of Invention

The invention aims to provide a method and a device for detecting eddy current thermal imaging defects of a steel wire rope, which can alleviate the problems.

In order to alleviate the above problems, the technical scheme adopted by the invention is as follows:

in a first aspect, the invention provides a method for detecting eddy current thermal imaging defects of a steel wire rope, which comprises the following steps:

using a known defect-free steel wire rope as a reference steel wire rope, and acquiring a plurality of reference thermal image data on the circumference of the steel wire rope by an eddy current thermal imaging method;

processing the reference thermal image data to obtain a reference steel wire rope temperature distribution model diagram;

detecting the motion position information data of the steel wire rope to be detected in the process of dragging the steel wire rope to be detected to move, and simultaneously acquiring a plurality of thermal image data to be detected on the circumference of the steel wire rope to be detected by an eddy current thermal imaging method;

processing the thermal image data to be detected in the same way as the reference thermal image data to obtain a temperature distribution model diagram of the steel wire rope to be detected;

and comparing the temperature distribution model diagram of the steel wire rope to be detected with the temperature distribution model diagram of the reference steel wire rope, finding out a defect part in the temperature distribution model diagram of the steel wire rope to be detected, and calibrating the position of the defect part according to the motion position information data to finish the defect detection of the steel wire rope to be detected.

The technical effect of the scheme is as follows: the thermal imaging method of the steel wire rope is adopted for thermal imaging of the steel wire rope, the response speed is high, and the steel wire rope which moves rapidly can be detected on line; when the thermal image data of the steel wire rope is acquired, the steel wire rope is not required to be contacted with a coupling agent, and the influence of external factors is small; the defect shape and position information is difficult to accurately judge in the traditional steel wire rope detection, and the shape information and the position information of the defect part can be accurately represented through a steel wire rope temperature distribution model diagram.

Further, the process of processing the thermal image data includes the steps of:

s1, carrying out image splicing and correction processing on a plurality of thermal image data of the circumferential section at the same position of the steel wire rope to obtain a steel wire rope temperature distribution model diagram I;

s2, setting a temperature threshold value, and removing image points lower than the temperature threshold value in the steel wire rope temperature distribution model diagram I to obtain a steel wire rope temperature distribution model diagram II;

s3, performing boundary repairing treatment on the steel wire rope temperature distribution model diagram II to obtain a steel wire rope temperature distribution model diagram III;

s4, extracting the contour of the steel wire rope temperature distribution model diagram III by using a contour extraction algorithm, obtaining a regularly distributed temperature field on the surface of the steel wire rope, and constructing to obtain a final steel wire rope temperature distribution model diagram.

The technical effect of the scheme is as follows: actual complete images on the circumference of the same position section of the steel wire rope can be obtained through splicing and correction; corresponding to the same circle segment, the obtained thermal images have overlapped parts, and only one layer of thermal image is reserved at the overlapped parts by setting a temperature threshold value and removing image points lower than the threshold value, so that the construction of a model image is facilitated; and finally, a complete model diagram can be obtained through boundary repair and contour extraction.

Further, in step S3, the boundary repair includes an open operation and a close operation.

The technical effect of the scheme is as follows: the opening operation is an operation of first corroding and then expanding, can eliminate fine objects, and separates the objects at the fine part and smoothes the boundary of a larger object; the closing operation is an operation of expansion followed by erosion, and can fill fine cavities in the object, connect adjacent objects and smooth boundaries.

Further, in the process of comparing and finding out the defect part, a comparison difference threshold value is set firstly, the temperature distribution model diagram of the steel wire rope to be detected and the temperature distribution model diagram of the reference steel wire rope are compared to obtain a comparison difference value, and in the temperature distribution model diagram of the steel wire rope to be detected, the part corresponding to the comparison difference value higher than the comparison difference threshold value is judged as the defect part.

The technical effect of the scheme is as follows: by setting a comparison difference threshold, the defect part can be quickly found.

In a second aspect, the present invention provides a steel wire rope eddy current thermal imaging defect detection apparatus, including:

the thermal infrared imager circumferential array is used for acquiring thermal image data on the circumference of the steel wire rope;

the position detection module is used for acquiring the motion position information data of the steel wire rope;

the high-frequency alternating current heater is used for heating the part of the steel wire rope, which needs to be subjected to thermal imaging;

and the data processing terminal is used for processing the thermal image data, finding out the defective part and calibrating the position of the defective part according to the motion position information data.

The technical effect of the scheme is as follows: the device for realizing the eddy current thermal imaging defect detection method of the steel wire rope is provided.

Further, the thermal infrared imager circumferential array comprises three high-frequency thermal infrared imagers, and when thermal image data on the circumference of the steel wire rope is obtained, the three high-frequency thermal infrared imagers are uniformly and circumferentially arranged at intervals of 120 degrees by taking the steel wire rope as a center.

The technical effect of the scheme is as follows: the circumferential arrays of the thermal infrared imagers are arranged in the circumferential direction at the angle, so that the field angles of the circumferential arrays are overlapped to form a closed continuous circumferential view angle, and the complete detection of the circumference of the steel wire rope is realized.

Further, the position detection module comprises an encoding wheel and a position signal processing module; the coding wheel is used for contacting with the steel wire rope and synchronously moving, and outputting a pulse signal representing the movement position of the steel wire rope to the position signal processing module; and the position signal processing module is used for receiving the pulse signal and converting the pulse signal into the motion position information data.

Furthermore, the coding wheel rotates under the driving of the steel wire rope, and once the coding wheel rotates for one circle, a pulse signal is sent to the position signal processing module.

The technical effect of the scheme is as follows: the movement position of the steel wire rope can be calculated conveniently according to the circumference of the coding wheel and the pulse signal.

Furthermore, the device also comprises a steel wire rope guide system, the steel wire rope guide system is used for guiding the steel wire rope to move linearly in the process of dragging the steel wire rope to move by the dragging device, and the coding wheel is arranged at a position close to the steel wire rope guide system.

The technical effect of the scheme is as follows: the reference steel wire rope can be limited to radially shake through the steel wire rope guide system, the steel wire rope in a traction motion state is guaranteed to be uniformly heated in the circumferential direction, and the coding wheel can be guaranteed to have better detection precision.

Furthermore, the high-frequency alternating current heater is provided with an alternating current heater water cooling device, and the alternating current heater water cooling device is used for cooling and protecting an excitation coil and an excitation source of the high-frequency alternating current heater.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic diagram of an application of a steel wire rope eddy current thermal imaging defect detection device for detection;

FIG. 2 is a schematic view of a defect in the surface of a steel cord to be inspected;

FIG. 3 is a schematic view of a high-frequency AC heater exciting coil for heating the surface of a steel wire rope to be detected all around;

FIG. 4 is a temperature profile of the heated surface of the wire rope to be inspected;

FIG. 5 is a model diagram of the temperature distribution of the steel wire rope to be detected after image processing;

FIG. 6 is a comparison of infrared thermal imager array images of a non-defective wire rope and a defective wire rope;

in the figure: the method comprises the following steps of 1-high-frequency alternating current heater excitation source, 2-alternating current heater water cooling device, 3-steel wire rope to be detected, 4-high-frequency alternating current heater excitation coil, 5-thermal infrared imager array, 6-steel wire rope guide system, 7-coding wheel, 8-position signal processing module, 9-PC end, 10-defect part, 11-heating temperature field, 12-temperature distribution of the steel wire rope at the defect-free position, and 13-temperature belt breakage at the defect position.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.