Method for electromagnetic detection of micro-iron filings in threaded pipes and detection device therefor

Abstract

The application discloses an electromagnetic detection method and device for a threaded pipe containing micro-iron filings, which is used for evaluating defects of a copper heat dissipation pipe used in air conditioners and the like by electromagnetic eddy current detection. The electromagnetic detection device is electrically connected to an eddy current detection analysis instrument. By increasing a magnetizing device, an additional magnetic field is added in the process of eddy current detection, so that the resolution of micro-iron filings in the copper pipe is improved. In the application, a permanent magnet is added on the basis of conventional external through-type eddy current detection, and is used for magnetizing the iron filings on the blade tip of a tool. Alternatively, an outer layer is designed as a magnetic saturation coil, and an inner layer is designed as a detection coil. In this way, the influence of the iron filings impurities on the pipe wall can be eliminated, and the detection sensitivity is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of non-destructive testing, in particular to an eddy current testing evaluation method for threaded metal pipes, and more particularly to an electromagnetic testing method for threaded pipes containing micro-iron filings and a detection device thereof. BACKGROUND

[0002] Threaded metal pipes are used in various industries, such as heat dissipation pipes, which are made of heat-conducting metal steel, copper and other materials to increase the contact area with air. Generally, heat dissipation pipes are made of copper pipes, which are widely used in the refrigeration and air conditioning industry due to their high thermal conductivity, strong corrosion resistance, good ductility and processability, and many other advantages. Currently, most air conditioner heat exchange pipes use threaded copper pipes, and the non-destructive testing of surface defects usually uses the eddy current method. However, in practice, when the threads of the copper pipe are processed using a tool knife (such as a steel knife), the blade tip of the tool knife can easily crack and adhere to the pipe wall if the pressure is too high during the internal and external thread processing of the pipe. As a result, there are ferromagnetic impurities on the pipe wall of the copper pipe, which makes it impossible to correctly obtain and detect surface defects.

[0003] To solve the above problems, the present application uses the following technical solutions for further improvement. SUMMARY

[0004] The purpose of the present application is to provide an electromagnetic testing method for threaded pipes containing micro-iron filings and a detection device thereof. The technical solutions disclosed are as follows:

[0005] An electromagnetic testing method for threaded pipes containing micro-iron filings is used for electromagnetic eddy current testing defect evaluation method for copper heat dissipation pipes used in air conditioners and the like. The method is electrically connected to an eddy current testing analysis instrument. By increasing the magnetic field during the eddy current testing process, the resolution of the micro-iron filings in the copper pipe is improved. The specific detection and evaluation analysis steps are as follows: a. Turn on the eddy current testing device: fix the eddy current testing device outside the detected metal pipe, start the excitation signal of the eddy current testing device, and turn on the eddy current testing sensor to receive the detection signal;

[0006] b. Start the magnetizing device: turn on the magnetizing device provided in the eddy current testing device to magnetically saturate the possible iron in the detected metal pipe;

[0007] c. Defect extraction: the eddy current testing analysis instrument receives the detection signal of the eddy current testing sensor, performs data analysis, reconstructs the defect signal data through the detection data image data, and stores and displays the defect signal data on the eddy current testing analysis instrument.

[0008] Further, the magnetization device in the b step is a permanent magnet arranged near the eddy current detection sensor coil. The permanent magnet can be a single piece or multiple pieces. The basic magnetization curve of the ferrous material, the size of the magnetic field strength H, the size of the additional magnetic flux density B¢ generated by the pipe wall magnetization, and the magnetic permeability m, in eddy current detection (including far-field eddy current detection), the primary magnetic field generated by the excitation current is usually small. The permanent magnet in the excitation coil provides a stable (direct current) bias magnetic field. The decrease in magnetic permeability enhances the skin effect of eddy current, and the detection signal changes significantly, which is completely different from the signal of the defect, thereby improving the detection accuracy.

[0009] Further, the permanent magnet is arranged as a ring-shaped permanent magnet ring composed of a plurality of pieces of opposite magnetic poles.

[0010] Further, the magnetization device is arranged as a coil surrounding the eddy current detection sensor coil, and the b step is to start the magnetization device at a certain frequency during the scanning detection process.

[0011] Further, the coil is arranged as a ring-shaped coil surrounding the outside of the eddy current detection sensor coil.

[0012] Further, the eddy current detection sensor coil in the a step is arranged as an array of ring-shaped eddy current detection coils, and each coil detects the eddy current signal value separately.

[0013] Further, the eddy current signal data value detected by the array of ring-shaped eddy current detection coils is analyzed by comparing the signal strength of each coil to analyze and calculate the radial position of the ferrous material.

[0014] Further, the defect extraction in the d step further includes comparing the changes in the eddy current signal values before and after magnetization to determine the detection signal value.

[0015] The application also discloses an electromagnetic detection device for a threaded pipe containing micro-iron filings, and an electromagnetic eddy current detection defect evaluation method for a copper heat dissipation pipe (1) with internal threads (11) used in air conditioners and the like. The detection device (2) is electrically connected to a multi-channel eddy current detection analysis instrument (3). By increasing a magnetic device (22), an additional magnetic field is added in the process of eddy current detection, micro-iron filings in the copper pipe are saturated magnetized, and the resolution of the micro-iron filings in the copper pipe is improved. The detection device comprises a detection sensor (21) and the magnetic device (22). The detection sensor (21) is arranged in the form of a ring array of a plurality of eddy current detection coils (211), and the magnetic device (22) is arranged in the form of an outer spiral coil (221) outside the ring array of the eddy current detection coils (211). Each ring array of the eddy current detection coils (211) is provided with a single channel of a detection eddy current signal value. The strength of the eddy current signal value of each coil is compared to determine the radial position of the iron filings in the detected metal pipe. The ring array of the eddy current detection coils (211) is arranged in the form of a planar spiral coil and is attached to the periphery of a ring-shaped flexible iron core film (23), which can serve as the effect of the core of the coil. The core has the effect of adsorbing magnetic lines. The adsorbed magnetic lines have two aspects of influence on the far-field eddy current detection: (1) changing the distribution of the magnetic field in the air in the pipe, so that the magnetic field is more concentrated near the excitation coil, thereby accelerating the attenuation of the direct coupling energy; and (2) increasing the eddy current in the pipe wall near the excitation coil, thereby strengthening the attenuation effect of the eddy current on the direct energy coupling. The results of the two aspects increase the difference between the micro-iron filings detection signal and the copper pipe defect detection signal, which helps to improve the accuracy of defect detection.

[0016] Further, the outer spiral coil (221) of the magnetic device (22) is also arranged as an excitation coil of the ring array of the eddy current detection sensor coils (211). When the outer spiral coil (221) is loaded with a direct current power supply, it serves as a magnetizing device of the detection device. When the outer spiral coil is loaded with an alternating power supply, it serves as an excitation coil of the eddy current detection sensor coil.

[0017] According to the above technical solution, the electromagnetic detection method and the detection device for a threaded pipe containing micro-iron filings increase a permanent magnet on the basis of conventional external through eddy current detection to magnetize the iron filings on the cutting tool. Alternatively, the design of an outer magnetic saturation coil and an inner detection coil can eliminate the influence of iron filings impurities on the pipe wall and improve the detection sensitivity. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the use state of the detection device of the best embodiment of the application;

[0019] Figure 2 The figure is a schematic diagram of the use state of the detection device of the best embodiment of the application;

[0020] Figure 3 The schematic diagram of the principle of the detection method of the best embodiment of the present application;

[0021] Figure 4 The schematic diagram of the magnetizing device of the detection device of the best embodiment of the present application;

[0022] Figure 5 The schematic diagram of the detection device of the best embodiment of the present application;

[0023] Figure 6 The schematic diagram of the magnetizing device of the detection device of the best embodiment of the present application;

[0024] Figure 7 The schematic diagram of the detection device of the best embodiment of the present application;

[0025] Figure 8 The schematic diagram of the detection signal of the best embodiment of the present application;

[0026] Figure 9 The schematic diagram of the magnetizing signal of the best embodiment of the present application. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings and specific embodiments.

[0028] As shown in the drawings, Figures 1 to 9 An electromagnetic detection method of a micro-iron chip-containing threaded pipe, which is used for the electromagnetic eddy current detection defect evaluation method of a copper heat dissipation pipe used in air conditioners and the like, is electrically connected to an eddy current detection analysis instrument, an additional magnetic field is added in the process of eddy current detection by means of increasing a magnetizing device, and the resolution of micro-iron chips in the copper pipe is improved. The specific detection evaluation and analysis steps are as follows: a. Turn on the eddy current detection device: externally fix the eddy current detection device on the outside of the metal pipe to be detected, start the excitation signal of the eddy current detection device, and turn on the eddy current detection sensor to receive the detection signal;

[0029] b. Start the magnetizing device: turn on the magnetizing device arranged on the eddy current detection device to magnetize the iron possibly existing in the metal pipe to be detected in a magnetic saturation mode;

[0030] c. Defect extraction: the eddy current detection analysis instrument receives the detection signal of the eddy current detection sensor, performs data analysis, reconstructs the defect signal data through the detection data image data, and stores and displays the defect signal data on the eddy current detection analysis instrument.

[0031] The magnetizing device in the b step is a permanent magnet arranged near the coil of the eddy current detection sensor.

[0032] As shown in the drawings, Figure 9As shown in the figure, the permanent magnet can be single piece or multiple pieces. The iron filings are ferromagnetic material, the basic magnetization curve of the ferromagnetic material, the size of the magnetic field strength H, the size of the additional magnetic flux density B generated by the tube wall magnetization, and the magnetic permeability U. In eddy current detection (including far field eddy current detection), the primary magnetic field generated by the excitation current is usually small, and the magnetic permeability changes in a small range near point a in the figure. The permanent magnet in the excitation coil provides a stable (direct current) bias magnetic field. When the size of this bias magnetic field is appropriate, the magnetic permeability changes near point b in the figure. As before, this will enhance the attenuation effect of eddy current on direct energy coupling. When the iron filings are saturated, the magnetic permeability changes near point c, the magnetic permeability decreases significantly, the skin effect of eddy current is enhanced, and the detection signal changes significantly, which is completely different from the signal of the defect, thereby improving the detection accuracy.

[0033] Figure 4 As shown in the figure, the permanent magnet is set as a ring-shaped permanent magnet ring composed of several pieces of opposite magnetic poles. Figure 5 As shown in the figure, the permanent magnet is set as a ring-shaped permanent magnet ring composed of several pieces of opposite magnetic poles.

[0034] As shown in the figure, the permanent magnet is set as a ring-shaped permanent magnet ring composed of several pieces of opposite magnetic poles. Figure 7 As shown in the figure, the magnetization device is a coil 221 arranged near the eddy current detection sensor coil. In one embodiment, the coil is arranged as a ring-shaped coil outside the eddy current detection sensor coil.

[0035] As shown in the figure, the magnetization device is a coil 221 arranged near the eddy current detection sensor coil. In one embodiment, the coil is arranged as a ring-shaped coil outside the eddy current detection sensor coil. Figure 5 Figure 7 As shown in the figure, the eddy current detection sensor coil is arranged as an annular array of eddy current detection coils, and each coil detects the value of the eddy current signal. The eddy current signal data detected by the annular array of eddy current detection coils is analyzed by comparing the signal strength of each coil to analyze and calculate the radial position of the iron filings.

[0036] As shown in the figure, the eddy current detection sensor coil is arranged as an annular array of eddy current detection coils, and each coil detects the value of the eddy current signal. The eddy current signal data detected by the annular array of eddy current detection coils is analyzed by comparing the signal strength of each coil to analyze and calculate the radial position of the iron filings. Figure 8 As shown in the figure, the eddy current detection sensor coil is arranged as an annular array of eddy current detection coils, and each coil detects the value of the eddy current signal. The eddy current signal data detected by the annular array of eddy current detection coils is analyzed by comparing the signal strength of each coil to analyze and calculate the radial position of the iron filings.

[0037] As shown in the figure, the eddy current detection sensor coil is arranged as an annular array of eddy current detection coils, and each coil detects the value of the eddy current signal. The eddy current signal data detected by the annular array of eddy current detection coils is analyzed by comparing the signal strength of each coil to analyze and calculate the radial position of the iron filings. Figure 1 Figure 2 Figure 7 ​​​As shown, the application also discloses an electromagnetic detection device for micro-iron filings threaded pipe, which is used for evaluating the electromagnetic eddy current detection defects of copper heat dissipation pipe (1) with internal threads (11) such as air conditioner, etc. The detection device (2) is electrically connected to a multi-channel eddy current detection analysis instrument (3). By increasing the magnetic device (22), an additional magnetic field is added during the eddy current detection process to saturate the micro-iron filings in the copper pipe and improve the resolution of the micro-iron filings in the copper pipe. The detection device (2) includes a detection sensor (21) and a magnetizing device (22). The detection sensor (21) is arranged as a ring array of several eddy current detection coils (211). The magnetizing device (22) is arranged as an outer spiral coil (221) outside the ring array of eddy current detection coils (211). Each ring array of eddy current detection coils (211) is detected by a single channel of eddy current signal value. By comparing the strength of the eddy current signal value of each coil, the radial position of the iron filings in the detected metal pipe is determined. The ring array of eddy current detection coils (211) is arranged as a planar spiral coil attached to the periphery of a ring-shaped flexible iron core film (23), which can act as the core effect of the coil. The core has the effect of adsorbing magnetic lines. The adsorbed magnetic lines have two aspects of influence on the far-field eddy current detection: (1) changing the distribution of the magnetic field in the air in the pipe, making the magnetic field more concentrated near the excitation coil, thereby accelerating the decay of direct coupling energy; (2) increasing the eddy current in the pipe wall near the excitation coil, strengthening the decay effect of eddy current on direct energy coupling. The results of the two aspects increase the difference between the micro-iron filings detection signal and the copper pipe defect detection signal, which helps to improve the accuracy of defect detection.

[0038] As shown in Figure 7 As shown, the outer spiral coil (221) of the magnetizing device (22) is also arranged as the excitation coil of the ring array of eddy current detection sensor coils (211). When the outer spiral coil (221) is loaded with a direct current power supply, it serves as a magnetizing device for detection. When the outer spiral coil is loaded with an alternating power supply, it serves as an excitation coil for the eddy current detection sensor coil.

[0039] The above is one embodiment of the application. In addition, it should be noted that any equivalent or simple changes made in accordance with the structure, features and principles described in the patent concept are included in the protection scope of the patent.

Claims

1. A method of electromagnetic examination of a threaded pipe containing micro-iron filings, characterized in that The electromagnetic detection device comprises a detection sensor and a magnetizing device, the detection sensor is arranged as a plurality of eddy current detection coils in a ring array, and the magnetizing device is arranged as an outer spiral coil outside the ring array of the eddy current detection coils, each ring array of the eddy current detection coils is detected by a single channel of eddy current signal value, the radial position of the iron filings in the detected metal pipe is determined by comparing the strength of the eddy current signal value of each coil, the resolution of the micro-iron filings in the copper pipe is improved by increasing the magnetic field during the eddy current detection through the method of increasing the magnetizing device, The specific detection evaluation and analysis steps are as follows: a. Turn on the eddy current detection device: fix the eddy current detection device outside the detected metal pipe, start the excitation signal of the eddy current detection device, and turn on the eddy current detection sensor to receive the detection signal; b. Start the magnetizing device: turn on the magnetizing device arranged on the eddy current detection device to magnetize the iron in the detected metal pipe in a magnetic saturation mode; c. Defect extraction: the eddy current detection analyzer receives the detection signal of the eddy current detection sensor, analyzes the data, reconstructs the defect signal data through the detection data image data, and stores and displays the defect signal data on the eddy current detection analyzer.

2. A method of electromagnetic inspection of a threaded pipe containing micro-iron filings according to claim 1, characterized in that The magnetizing device in step b is a permanent magnet arranged near the eddy current detection sensor coil.

3. A method of electromagnetic inspection of a threaded pipe containing micro-iron filings according to claim 2, characterized in that The permanent magnet is arranged as a ring-shaped permanent magnet ring combined by a plurality of opposite magnetic poles.

4. A method of electromagnetic inspection of a threaded pipe containing micro-iron filings according to claim 1, characterized in that The magnetizing device is arranged as a coil surrounding the eddy current detection sensor coil, and the magnetizing device is started in step b by being turned on and off at a certain frequency during the scanning detection process.

5. A method of electromagnetic inspection of a threaded pipe containing micro-iron filings according to claim 4, characterized in that The coil is arranged as a ring-shaped coil outside the eddy current detection sensor coil.

6. A method of electromagnetic inspection of a threaded pipe containing micro-iron filings according to claim 5, characterized in that The eddy current detection sensor coil in step a is arranged as a ring array of eddy current detection coils, and each coil is detected by a single channel of eddy current signal value.

7. A method of electromagnetic inspection of a threaded pipe containing micro-iron filings according to claim 3 or 6, characterized in that The eddy current signal data value detected by the ring array of the eddy current detection coil is analyzed by comparing the signal strength of each coil to analyze and calculate the radial position of the iron filings.

8. A method of electromagnetic inspection of a micro-iron particle containing threaded pipe according to claim 7, characterized in that The defect extraction in step d also includes comparing the different changes of the eddy current signal value before and after magnetization to determine the detection signal value.

9. An electromagnetic testing apparatus for micro-ferrous threaded pipes, comprising a detection sensor (21) and a magnetizing device (22), characterized in that The detection sensor (21) is arranged as a plurality of eddy current detection coils (211) in a ring array, the magnetizing device (22) is arranged as an outer spiral coil (221) outside the ring array of the eddy current detection coils (211), each ring array of the eddy current detection coils (211) is detected by a single channel of eddy current signal value, and the radial position of the iron filings in the detected metal pipe is determined by comparing the strength of the eddy current signal value of each coil.

10. An electromagnetic inspection apparatus for ferrous-containing threaded pipe as defined in claim 9, wherein The outer spiral coil (221) of the magnetizing device (22) is also arranged as an excitation coil of the ring array of the eddy current detection coil (211).

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