Nondestructive testing method and device for pitch of multi-core cable

Abstract

The invention discloses a nondestructive testing method and device for the pitch of a multi-core cable. The magnetic sensor moves along the surface of the cable, and when the cable is powered on, a magnetic field is generated around due to the action of current in the cable. The magnetic sensor converts detected magnetic field changes into electric signals and transmits the electric signals to the signal processing device. The signal receiving device is used for reading signals of the magnetic sensor, and the signal processing device is used for drawing an image and calculating an obtained cable pitch result, so that an operator can know the pitch condition of the cable in real time. The pitch of the cable can be measured by measuring the distance between two adjacent positions with the maximum magnetic field intensity. Based on the magnetic field detection principle and the sensor technology, the device can accurately capture the fine change of the magnetic field intensity around the cable, can accurately measure the pitch of the cable through data analysis, and achieves the real-time online detection of the pitch of the cable.

Description

Technical Field

[0001] The invention belongs to the technical field of cable detection, and relates to a nondestructive detection method and device for a multi-core cable pitch. The pitch of the cable is determined by detecting magnetic field strength signals at different positions on the cable surface. Background Art

[0002] In the process of cable manufacturing and use, the pitch control of multi-core cables is very important. With the continuous development of science and technology and the increasing requirements of cable performance in various industries, the demand for accurate detection of multi-core cable pitch is becoming more and more urgent.

[0003] In the early days of cable manufacturing, people gradually realized that twisting the wires could improve the flexibility and mechanical strength of the cable. However, with the advancement of technology and the continuous expansion of application scenarios, the simple twisting process can no longer meet complex performance requirements. Different types of cables, such as power cables and communication cables, have different requirements for pitch due to their specific uses and performance requirements. Power cables require higher mechanical strength and current carrying capacity, and the choice of pitch will directly affect their heat dissipation and electrical performance. Communication cables pay more attention to the transmission quality of signals, and pitch control is crucial to reducing signal attenuation and interference.

[0004] It can be seen that in the cable production process, the pitch of the cable is an important parameter. Accurately measuring the cable pitch is crucial to ensuring the quality, performance and subsequent safety of the cable. At present, the commonly used cable pitch measurement methods are machine vision, X-ray detection, and ultrasonic detection. These detection methods have problems such as complex algorithms and long time consumption, great influence of light, high safety management requirements, and harsh detection environment requirements, which make it difficult to meet the requirements of efficient production and quality control. Therefore, it is of great practical significance to develop a simple and efficient method for non-destructive detection of multi-core cable pitch. This method can not only accurately measure the cable pitch to ensure that the cable performance meets the requirements, but also perform rapid detection without damaging the cable, improve production efficiency and quality control level, and meet the high standards of modern industry for cable manufacturing and application. Summary of the invention

[0005] In order to more accurately measure the pitch of a multi-core cable, the present invention provides a device and method for measuring the pitch of a cable based on a magnetic field sensor. The device and method detect the cable using the magnetic field generated by the currents of different conductive cores inside the cable, and based on the device and method, the cable pitch can be measured quickly and accurately.

[0006] In a first aspect, the present invention provides a nondestructive testing device for a multi-core cable pitch, comprising a magnetic sensor system and a magnetic field strength testing system;

[0007] The magnetic sensor system comprises a magnetic sensor and a sliding mechanism, wherein the magnetic sensor is arranged directly above the cable, and the magnetic sensor moves along the axial direction of the cable through the sliding mechanism;

[0008] The magnetic field strength detection system includes a signal receiving device and a signal processing device; the signal receiving device is used to receive the magnetic field strength signal of the magnetic sensor, and the signal processing device obtains the magnetic field strength output by the signal receiving device and draws a change curve image, thereby obtaining the pitch of each core in the cable.

[0009] Preferably, the magnetic sensor system further comprises a magnetic shielding shell, the side of the magnetic shielding shell facing the cable is an open surface, and the magnetic sensor is arranged in the magnetic shielding shell.

[0010] Preferably, the magnetic sensor system further comprises a power supply module to supply power to the magnetic sensor.

[0011] Preferably, the sliding mechanism includes a bracket, a slide rail, and a fixing mechanism; the bracket is provided with two parallel slide rails, and the slide rails are arranged parallel to the cable; the fixing mechanism is used to fix the magnetic sensor, and sliders matching the slide rails are arranged on both sides of the fixing mechanism; the fixing mechanism is moved by a motor driving mechanism to perform horizontal movement along the slide rails.

[0012] Preferably, there is a certain distance between the magnetic sensor and the cable.

[0013] In a second aspect, the present invention provides a non-destructive testing method for a multi-core cable pitch, the method comprising:

[0014] Step (1): Build a signal acquisition platform

[0015] 1-1 Keep the cable in a straight state, the cable is a multi-core twisted cable, that is, it has different conductive cores, and a stable current is passed through one of the conductive cores;

[0016] 1-2 Adjust the sliding mechanism so that the magnetic sensor is directly above the cable;

[0017] 1-3 Adjust the sliding mechanism, move the magnetic sensor to one end of the cable, and set the magnetic sensor position X at this time as the origin coordinate;

[0018] Step (2), collecting the magnetic field strength B(X) above the cable, drawing a curve of the magnetic field strength B(X) changing with the magnetic sensor position X, and obtaining all the pitches of the current conductive core;

[0019] 2-1 Use the sliding mechanism to move the magnetic sensor horizontally above the cable along the cable axis until it reaches the other end of the cable;

[0020] 2-2 The magnetic sensor measures the magnetic field above the cable in real time, and the signal receiving device obtains the magnetic field strength B(X) of the magnetic sensor;

[0021] 2-3 Draw a magnetic field intensity change curve with the magnetic sensor position X as the horizontal coordinate and the magnetic field intensity B(X) as the vertical coordinate;

[0022] 2-4 Starting from the origin coordinate of the magnetic sensor position X, find two adjacent magnetic field intensity peaks one by one in the magnetic field intensity change curve, obtain the current pitch according to the corresponding magnetic sensor position, and then obtain all the pitches of the current conductive core;

[0023] Step (3), pass a stable current through another conductive core, move the magnetic sensor to the origin coordinate, and repeat step (2) until the pitch measurement of all conductive cores in the cable is completed.

[0024] Preferably, the cable is a three-core cable.

[0025] Preferably, each pitch is calculated as follows:

[0026] Y i =|X i1 -X i2 | (1)

[0027] Where X i1 , X i2 Represent the adjacent magnetic field intensity peaks, Y i represents the i-th pitch.

[0028] Preferably, during the measurement process, the vertical distance between the magnetic sensor and the cable remains unchanged, and the cable length should be greater than the length of one pitch.

[0029] Preferably, during the measurement process, the magnetic sensor slides at a constant speed.

[0030] The beneficial effects of the present invention include at least the following:

[0031] Relying on the magnetic field detection principle and sensor technology, the present invention can accurately capture subtle changes in the magnetic field strength around the cable. Through data analysis, the pitch of the cable can be accurately measured, which effectively guarantees the performance stability and safety of the cable product during subsequent use.

[0032] The present invention realizes real-time online detection of cable pitch, and there is no need to perform cumbersome disassembly, pretreatment and other complex physical operations on the cable during the detection process. The detection process is efficient and smooth, and the cable pitch data can be quickly obtained in a short time, which greatly shortens the detection cycle, making the quality monitoring in the cable production process more timely and efficient, helping enterprises to discover and solve pitch problems in a timely manner, ensuring that the production progress is not delayed, and effectively improving production efficiency and economic benefits.

[0033] The present invention is not limited by the cable type, and is applicable to power cables, communication cables, or other types of multi-core cables. It has important practical value and broad application prospects in the field of multi-core cable pitch detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a signal transmission flow chart of the device of the present invention.

[0035] Figure 2 Schematic diagram of the application of the device of the present invention.

[0036] Figure 3 This is a graph of the experimental results of the present invention.

[0037] Markings in the figure: 1. magnetic sensor; 2. fixing mechanism; 3. slide rail; 4. cable. DETAILED DESCRIPTION

[0038] From the background technology, it can be seen that the existing commonly used methods such as machine vision are easily affected by the unpredictable interference of lighting conditions, and the complex algorithms make the processing flow lengthy and tedious, seriously delaying the detection timeliness; the X-ray detection method is constrained by strict safety control regulations and special detection environment adaptation requirements, and the implementation difficulty and cost remain high; when dealing with the complex structure of multi-core cables, the ultrasonic detection method has complex and cumbersome signal analysis and it is difficult to improve the accuracy.

[0039] Therefore, in order to solve the above dilemma, the present invention proposes a non-destructive detection device for the pitch of a multi-core cable, including a magnetic sensor, a signal receiving device, and a signal processing device. The magnetic sensor uses a sliding device to enable it to move along the surface of the cable, and a magnetic shielding shell is installed on the outside of the magnetic sensor to prevent interference from the external magnetic field, and the magnetic field changes around the moving detection cable. When the cable is energized, a magnetic field will be generated around it due to the action of the current inside the cable. The magnetic sensor converts the detected magnetic field changes into electrical signals and transmits them to the signal processing device. The signal receiving device is used to read the signal of the magnetic sensor, and the signal processing device is used to draw an image and calculate the cable pitch result so that the operator can understand the pitch of the cable in real time. The pitch of the cable can be measured by measuring the distance between the positions of the maximum magnetic field intensity of two adjacent locations.

[0040] The cable used in the present invention is a multi-core twisted cable, such as a common power cable or communication cable, and the number and material of its cores must meet specific testing standards. Taking a three-core cable as an example, its core material may be copper or aluminum, and the twisting process must ensure a tight and uniform structure.

[0041] The method is further analyzed below in conjunction with the accompanying drawings.

[0042] This embodiment provides a nondestructive testing device for a multi-core cable pitch, including a magnetic sensor system and a magnetic field strength testing system;

[0043] The magnetic sensor system includes a magnetic sensor, which is arranged directly above the cable;

[0044] The magnetic field strength detection system includes a signal receiving device and a signal processing device; the signal receiving device is used to receive the magnetic field strength signal of the magnetic sensor, and the signal processing device obtains the magnetic field strength output by the signal receiving device and draws an image, thereby obtaining the pitch of each core in the cable.

[0045] Figure 1 It is a signal transmission flow chart of the device of the present invention.

[0046] In one embodiment, the magnetic sensor system further includes a magnetic shielding shell and a sliding mechanism, and the magnetic sensor realizes axial movement along the cable through the sliding mechanism; the magnetic shielding shell covers the magnetic sensor to prevent interference from the external magnetic field. The magnetic shielding shell is an open surface facing the cable side, that is, a square shell with only five faces. The material of the magnetic shielding shell is Permalloy. Preferably, the magnetic sensor system also includes a power module to power the magnetic sensor and the motor that controls the sliding mechanism.

[0047] One implementation method is shown in Figure 2 , the sliding mechanism includes a bracket, a slide rail, a fixing mechanism, and a motor; two parallel slide rails are arranged on the bracket, and the slide rails are arranged parallel to the cable; the sliding mechanism is made of non-magnetic material. The fixing mechanism is used to firmly fix the magnetic sensor, and the sliders on both sides thereof are matched with the slide rails with a clearance, and the clearance value is generally controlled between 0.03-0.08mm, which can ensure that the magnetic sensor can move smoothly along the slide rail and avoid shaking or offset due to excessive clearance. The motor can use a high-precision DC servo motor. The controller controls the speed and direction of the motor by sending precise pulse signals. For example, when the magnetic sensor is required to move at a constant speed of 5cm / s, the controller calculates the corresponding pulse frequency according to the preset algorithm and the parameters of the motor, which is generally between 1000-5000Hz, and accurately drives the motor to operate, thereby driving the fixing mechanism and the magnetic sensor to move horizontally along the cable axis. During the movement, the motor encoder feeds back position information to the controller in real time. The controller performs closed-loop control based on the feedback information to ensure that the position accuracy of the magnetic sensor can reach within ±0.1mm, thereby ensuring the accuracy of the measurement.

[0048] The pitch nondestructive testing device of this embodiment further includes a controller, and the motor is controlled by the controller of the magnetic field strength testing system.

[0049] This embodiment also provides a non-destructive detection method for the pitch of a multi-core cable, including:

[0050] Step (1): Build a signal acquisition platform

[0051] 1-1 Keep the cable in a straight state. The cable is a multi-core twisted cable, that is, it has different conductive cores, such as a three-core cable. A stable DC current is passed through one of the conductive cores through a power module to keep it horizontal and straight. The selected length should be greater than the length of one pitch.

[0052] The selected cable length is greater than the length of one pitch to ensure that the magnetic field change data of at least one cycle can be completely obtained. For example, for a cable with a pitch of 3-8 meters, a 10-15 meter cable sample is usually selected for testing.

[0053] 1-2 Adjust the sliding mechanism so that the magnetic sensor is directly above the cable;

[0054] 1-3 Adjust the sliding mechanism, move the magnetic sensor to one end of the cable, and set the magnetic sensor position X at this time as the origin coordinate.

[0055] During the measurement process, the vertical distance between the magnetic sensor and the cable remains unchanged, the current flowing through the cable is a direct current, and the selected cable length should be greater than the length of one pitch.

[0056] Step (2), collecting the magnetic field strength B(X) above the cable, and drawing a curve of the magnetic field strength B(X) versus the position X of the magnetic sensor;

[0057] 2-1 Use a sliding mechanism to move the magnetic sensor horizontally above the cable along the cable axis until it reaches the other end of the cable. The vertical distance between the installation position of the magnetic sensor and the cable is 5 cm. During the measurement process, the magnetic sensor slides at a constant speed.

[0058] 2-2 The magnetic sensor measures the magnetic field above the cable in real time, and the signal receiving device obtains the magnetic field strength B(X) of the magnetic sensor;

[0059] 2-3 Draw a magnetic field intensity change curve with the magnetic sensor position X as the horizontal coordinate and the magnetic field intensity B(X) as the vertical coordinate;

[0060] 2-4 Starting from the origin coordinate of the magnetic sensor position X, find two adjacent magnetic field intensity peaks one by one in the magnetic field intensity change curve, obtain the current pitch according to the corresponding magnetic sensor position, and then obtain all the pitches of the current conductive core; each pitch is calculated as follows:

[0061] Y i =|X i1 -X i2 | (1)

[0062] Where Xi1 , X i2 Represent the adjacent magnetic field intensity peaks, Y i represents the i-th pitch;

[0063] Step (3), repeat the above operation until the pitch measurement of all the conductive cores in the cable is completed.

[0064] like Figure 3 As shown in the experimental result diagram, it shows the relationship between the magnetic sensor position X (abscissa) above the cable and the magnetic field strength B(X) (ordinate).

[0065] The magnetic sensor used in the actual example is a fluxgate sensor. A three-core cable is used for the experiment. The experimental platform is set to be parallel to the three-core cable and placed 5 cm above the three-core cable. The fluxgate sensor is moved at a constant speed using a sliding mechanism to collect the magnetic field signal above the three-core cable. The signal receiving device uses a data acquisition system that matches the fluxgate sensor. The signal processing device draws a curve image of the change of the magnetic field intensity B(X) through the host computer system.

[0066] The fluxgate sensor detects the magnetic field strength based on the change in the magnetic permeability of the magnetic material. After the cable is powered on, the magnetic field generated in the surrounding will cause the magnetic flux of the magnetic material inside the fluxgate sensor to change, thereby generating an induced electromotive force. After amplification, filtering and analog-to-digital conversion by the signal conditioning circuit, the magnetic field strength signal is transmitted to the signal receiving device in digital form. The signal receiving device uses a high-speed data acquisition card with a sampling frequency of up to 10kHz or more, which can quickly and accurately collect the signal output by the magnetic sensor and transmit it to the signal processing device.

[0067] During the experiment, the center of the three-core cable was used as the center of the experimental platform. The length of the three-core cable was 15m, and the pitch of each conductive core in the three-core cable was 5m. Figure 3 As shown, a 1A DC current is passed through one of the three-core cable cores. Starting from 0m, the fluxgate sensor is uniformly operated at a speed of 10cm / s on the experimental platform and the magnetic field intensity B(X) at different positions is recorded. The B(X) image is drawn with the magnetic sensor position X as the horizontal coordinate and the magnetic field intensity B as the vertical coordinate. Similar result images can be obtained by energizing the other two conductive cores and repeating the above steps.

[0068] pass Figure 3 It can be seen that the distance between two adjacent maximum points of the magnetic field intensity B(X) is 5 m, which is the same as the length of the actual pitch, verifying the feasibility of the method of the present invention.

[0069] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A nondestructive testing device for multi-core cable pitch, characterized in that: It includes a magnetic sensor system and a magnetic field strength detection system; The magnetic sensor system comprises a magnetic sensor and a sliding mechanism, wherein the magnetic sensor is arranged directly above the cable, and the magnetic sensor moves along the axial direction of the cable through the sliding mechanism; The magnetic field strength detection system includes a signal receiving device and a signal processing device; the signal receiving device is used to receive the magnetic field strength signal of the magnetic sensor, and the signal processing device obtains the magnetic field strength output by the signal receiving device and draws a change curve image, thereby obtaining the pitch of each core in the cable.

2. The device according to claim 1, characterized in that: The magnetic sensor system further includes a magnetic shielding case, wherein a side of the magnetic shielding case facing the cable is an open surface, and the magnetic sensor is disposed in the magnetic shielding case.

3. The device according to claim 1, characterized in that: The magnetic sensor system also includes a power module for supplying power to the magnetic sensor.

4. The device according to claim 1, characterized in that: The sliding mechanism includes a bracket, a slide rail, and a fixing mechanism; the bracket is provided with two parallel slide rails, and the slide rails are arranged parallel to the cable; the fixing mechanism is used to fix the magnetic sensor, and sliders matching the slide rails are arranged on both sides of the fixing mechanism; the fixing mechanism moves horizontally along the slide rails through the movement of the motor drive mechanism.

5. The device according to claim 1, characterized in that: The magnetic sensor is at a certain distance from the cable.

6. A non-destructive testing method for the pitch of a multi-core cable based on the device according to any one of claims 1 to 5, characterized in that: The method comprises: Step (1): Build a signal acquisition platform 1-1 Keep the cable in a straight state, the cable is a multi-core twisted cable, that is, it has different conductive cores, and a stable current is passed through one of the conductive cores; 1-2 Adjust the sliding mechanism so that the magnetic sensor is directly above the cable; 1-3 Adjust the sliding mechanism, move the magnetic sensor to one end of the cable, and set the magnetic sensor position X at this time as the origin coordinate; Step (2): Collect the magnetic field strength above the cable , plotting the magnetic field strength The curve that changes with the position X of the magnetic sensor obtains all the pitches of the current conductive core; 2-1 Use the sliding mechanism to move the magnetic sensor horizontally above the cable along the cable axis until it reaches the other end of the cable; 2-2 The magnetic sensor measures the magnetic field above the cable in real time, and the signal receiving device obtains the magnetic field strength of the magnetic sensor ; 2-3 Take the magnetic sensor position X as the horizontal coordinate and the magnetic field strength Draw a curve of magnetic field intensity variation for the ordinate; 2-4 Starting from the origin coordinate of the magnetic sensor position X, find two adjacent magnetic field intensity peaks one by one in the magnetic field intensity change curve, obtain the current pitch according to the corresponding magnetic sensor position, and then obtain all the pitches of the current conductive core; Step (3), pass a stable current through another conductive core, move the magnetic sensor to the origin coordinate, and repeat step (2) until the pitch measurement of all conductive cores in the cable is completed.

7. The method according to claim 6, characterized in that: The cable is a three-core cable.

8. The method according to claim 6, characterized in that: Each pitch is calculated as follows: （1） in represent the adjacent magnetic field intensity peaks, represents the i-th pitch.

9. The method according to claim 6, characterized in that: During the measurement process, the vertical distance between the magnetic sensor and the cable remains unchanged, and the cable length should be greater than the length of one pitch.

10. The method according to claim 6, characterized in that: During the measurement process, the magnetic sensor slides at a constant speed.

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