A method for detecting hidden cracks in magnetic products and a detection device used in the method

Abstract

The present invention discloses a method for detecting dark cracks in magnetic products, comprising the following steps: making a pressure-type magnetic product dark crack detection device; selecting a number of defective magnetic products with dark crack defects, and determining the detection pressure of the pressure-type magnetic product dark crack detection device by pressure verification of the defective products; inputting the product to be inspected into the pressure-type magnetic product dark crack detection device; performing a pressure test on the product to be inspected using the detection pressure obtained in step one; and sorting out the product to be inspected that is damaged under the detection pressure as a defective product. The present invention also discloses a pressure-type magnetic product dark crack detection device applied to the magnetic product dark crack detection method. The present invention uses a pressure-type magnetic product dark crack detection device to replace manual audio detection, and products with dark crack defects have a rapid response to external pressure, thereby having higher detection efficiency and accuracy.

Description

Technical Field

[0001] The present invention relates to a method for detecting magnetic products and related devices, and more particularly, to a method for detecting hidden cracks in magnetic products and a detection device applied thereto. Background Art

[0002] High-quality magnetic products must not only meet customer requirements for magnetic performance and dimensions, but also their physical properties, particularly mechanical strength, are crucial parameters for evaluating product quality. For example, if a magnetic tile does not meet mechanical strength standards, it could break or fracture during magnetization or use when installed in a motor, potentially causing the motor rotor to seize. Therefore, 100% control is essential during the magnetic tile production process to prevent the release of tiles with hidden cracks. This is especially true for automotive motors, such as ABS motors, seat motors, rocker motors, and fan motors. These motors are not only in high demand and frequently used, but also directly impact user experience and even personal safety. Therefore, the strength requirements for the magnetic components used in these motors are extremely high. Currently, hidden crack detection relies solely on manual listening, which is inefficient and inaccurate. Given the large market demand and production volumes for automotive motors, there is an urgent need for a hidden crack detection device to replace manual listening. The utility model patent with publication number CN210037489U discloses a magnetic tile crack detection device, which includes a workbench, a feed table, a conveying device, a striking device, and a discharge chute. The feed table is fixed to the workbench by a support, one end of the conveying device is connected to the feed table, and the other end of the conveying device is connected to the discharge chute. The striking device includes a column fixed to the workbench, the column is placed on one side of the conveying device, a mounting plate is provided on the column, a support frame is provided at the front end of the mounting plate, a sensor is provided on the support frame, a cylinder is provided at the rear end of the mounting plate, and a striking hammer is provided at the output end of the cylinder. The sensor and the striking hammer are respectively arranged above the conveying device. This utility model is used for crack detection of magnetic tiles. It detects products containing cracks by striking the magnet with a striking hammer. It has a simple structure, easy operation, and high work efficiency. However, the device is fed into the equipment manually, and the force is applied by striking. The instantaneous impact force can cause damage to the product. Moreover, the device cannot verify the strength of the impact force applied. Once the impact force is abnormal and cannot be discovered in time, it is very easy to cause secondary damage to the product being inspected. Summary of the Invention

[0003] The existing magnetic tile crack detection method has low detection efficiency and poor accuracy. To overcome these defects, the present invention provides a magnetic product hidden crack detection method with higher detection efficiency and better accuracy and a detection device applied to the method.

[0004] The technical solution of the present invention is: a method for detecting hidden cracks in magnetic products, comprising the following steps:

[0005] Step 1. Make a pressure-type magnetic product hidden crack detection device;

[0006] Step 2. Select several defective magnetic products with dark crack defects and determine the detection pressure of the pressure-type magnetic product dark crack detection device by pressure verification on the defective products;

[0007] Step 3. Input the product to be inspected into the pressure-type magnetic product hidden crack detection device;

[0008] Step 4. Perform a pressure test on the product to be tested at the test pressure obtained in step 1;

[0009] Step 5. The products to be inspected that are damaged under the inspection pressure are sorted out as defective products.

[0010] The present invention uses a pressure-type magnetic product dark crack detection device to detect cracks in magnetic products. The detection method is different from the acoustic detection method. When implementing this magnetic product dark crack detection method, a suitable detection pressure is selected and applied to the product to be inspected. Products with dark cracks have poor strength and are likely to directly shatter under the action of the detection pressure. Good products themselves have high strength and can withstand the detection pressure without being damaged. The existing acoustic detection method is not only due to the blurred sound resolution boundary, but the final judgment is also greatly affected by the skill level and experience of the personnel. When using this pressure-type magnetic product dark crack detection device for detection, products with dark crack defects have an intuitive and rapid response to external pressure, thus having higher detection efficiency and accuracy.

[0011] Preferably, the implementation process of step 2 includes the following steps:

[0012] Step 2.1. Select defective magnetic products with dark cracks by using the acoustic method;

[0013] Step 2.2. Perform a destructive test on each defective magnetic product by applying pressure on a press. The pressure at which the defective magnetic product breaks is used as the strength value and recorded in a table.

[0014] Step 2.3. Select the maximum value among the recorded intensity values ​​and increase it by 10%-15% as the initial test pressure.

[0015] Step 2.4. Select several magnetic products and place them one by one on the pressure-type magnetic product hidden crack detection device. Pressure test the magnetic products one by one at the same initial test pressure, and select several magnetic products that remain intact after the test as good products. Select the same number of magnetic products from the same batch of magnetic products using the acoustic method.

[0016] Step 2.5. Perform destructive tests on the two batches of qualified magnetic products on the press again, and obtain the strength values ​​of the two batches of qualified magnetic products and record them in a table; compare the strength values ​​of the two batches of qualified magnetic products. If it is found that the strength value of the qualified products obtained by the pressure test is greater than or equal to the strength value of the qualified products obtained by the acoustic method, or the strength value of the qualified products obtained by the pressure test is less than the strength value of the qualified products obtained by the acoustic method, but the error is within the allowable range, it can be determined that the initially determined test pressure will not cause secondary damage, and the initially determined test pressure is determined as the final test pressure; if it is found that the strength values ​​of the qualified products obtained by the pressure test and the qualified products obtained by the acoustic method are lower and the error is beyond the allowable range, it can be determined that the initially determined test pressure has caused secondary damage to the magnetic products, reselect the initial test pressure, and repeat steps 2.4 and 2.5.

[0017] It is necessary to conduct tests to determine the detection pressure of the pressure-type magnetic product dark crack detection device. The detection pressure obtained through the above steps is greater than the strength value of the magnetic product with dark cracks, which can ensure that the magnetic products with dark cracks are destroyed and reduce the false detection rate. On the other hand, the detection pressure must be controlled to avoid being large enough to destroy good products without dark cracks and cause secondary damage to the products.

[0018] As a preference, the defective products picked out in step 5 are automatically sent to the waste pool, which ensures that the defective products will not flow into the subsequent process.

[0019] Preferably, the pressure-type magnetic product hidden crack detection device is installed between a grinder and a cleaning machine. Magnetic products must be ground and shaped on a grinder to achieve a usable form. After being inspected by this pressure-type magnetic product hidden crack detection device, the product enters an ultrasonic cleaning machine for final processing before being put into use. This pressure-type magnetic product hidden crack detection device, placed between the grinder and the cleaning machine, enables automated production.

[0020] A pressure-type device for detecting hidden cracks in magnetic products comprises a base, a conveyor belt, a detection platform, and a pressure roller. The conveyor belt and pressure roller are positioned above the base, with the detection platform located between the base and the pressure roller. The magnetic product is conveyed by friction from the conveyor belt. Once it reaches the detection platform, it is rolled and pushed by the pressure roller. While continuing to be conveyed, it is subjected to the detection pressure applied by the pressure roller, completing the detection of hidden cracks. This pressure-type device for detecting hidden cracks in magnetic products offers higher detection efficiency and accuracy.

[0021] Preferably, a pressure sensor is provided at the bottom of the testing platform. The testing pressure applied by the pressure wheel to the magnetic product is ultimately transmitted to the pressure sensor, which can monitor the working status of the pressure wheel in real time and detect abnormalities in a timely manner.

[0022] Preferably, a conveying guide groove is provided on the top of the base, and the detection platform is located at the end of the conveying guide groove. The conveying guide groove forms a fixed conveying path, and the magnetic product can be accurately conveyed to the detection platform in the conveying guide groove without deviation.

[0023] Preferably, the inspection platform comprises a platform, a roller, and a support shaft. The platform is topped with a platform top groove, the same width as the conveyor guide groove. The support shaft runs transversely through the platform and is rotatably connected to it. The roller is embedded in the bottom of the platform top groove, with its apex protruding above the bottom of the platform top groove. The roller and the support shaft are in rolling contact. The roller supports the product to be inspected, allowing it to be suspended in mid-air. The pressure roller applies pressure to the product at the suspended portion of the product. Hidden cracks in this suspended portion can easily cause it to break.

[0024] Preferably, the pressure-type magnetic product hidden crack detection device further comprises a pressure display electrically connected to the pressure sensor. The pressure display visualizes the monitoring results of the pressure sensor, making it easier for operators to read and determine the detection results.

[0025] The beneficial effects of the present invention are:

[0026] Improve detection efficiency. The present invention uses a pressure-type magnetic product hidden crack detection device to replace manual audio detection. Products with hidden crack defects have a rapid response to external pressure, thus having higher detection efficiency.

[0027] Improve detection accuracy. The present invention uses a pressure-type magnetic product hidden crack detection device to replace manual audio detection. Products with hidden crack defects have an intuitive response to external pressure, presenting the detection results in a fragmented state. The detection results are easy to judge and are not easily affected by the skill level and experience of the personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the pressure-type magnetic product hidden crack detection device of the present invention;

[0029] Figure 2 Schematic diagram of the structure of the detection platform in the present invention;

[0030] Figure 3 This is a schematic diagram of the state of the pressure-type magnetic product hidden crack detection device in the present invention when the flap is closed during operation;

[0031] Figure 4 This is a schematic diagram of the state of the pressure-type magnetic product hidden crack detection device when the flap is open during operation of the present invention.

[0032] In the figure, 1-base, 2-conveyor belt, 3-detection platform, 4-pressure wheel, 5-conveyor guide groove, 6-platform, 7-roller, 8-support shaft, 9-platform top groove, 10-pressure display, 11-pressure sensor, 12-support bar, 13-blank mouth, 14-flip plate. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to specific embodiments of the drawings.

[0034] Example 1:

[0035] like Figures 1 to 4 As shown, a method for detecting hidden cracks in magnetic products comprises the following steps:

[0036] Step 1. Make a pressure-type magnetic product dark crack detection device and install the pressure-type magnetic product dark crack detection device between the grinder and the cleaning machine of the magnetic product production line;

[0037] Step 2. Select several defective magnetic products with dark crack defects and determine the detection pressure of the pressure-type magnetic product dark crack detection device by pressure verification on the defective products;

[0038] Step 3. Input the product to be inspected into the pressure-type magnetic product hidden crack detection device;

[0039] Step 4. Perform a pressure test on the product to be tested at the test pressure obtained in step 1;

[0040] Step 5. The products to be inspected that are damaged under the inspection pressure are sorted out as defective products and automatically sent to the waste pool.

[0041] The implementation process of step 2 specifically includes the following steps:

[0042] Step 2.1. Select defective magnetic products with dark cracks by using the acoustic method;

[0043] Step 2.2. Perform a destructive test on each defective magnetic product by applying pressure on a press. The pressure at which the defective magnetic product breaks into pieces is used as the strength value and recorded in a table.

[0044] Step 2.3. Select the maximum value of 536N from the recorded strength values ​​and increase it by 12%, i.e. 600N, as the initial test pressure.

[0045] Step 2.4. Select 60 magnetic products and place them one by one on the pressure-type magnetic product hidden crack detection device. Test each magnetic product with an initial test pressure of 600N. After the test, if all 60 magnetic products remain intact, they are determined to be good products. Select another 60 good magnetic products from the same batch of magnetic products using the acoustic method.

[0046] Step 2.5. The two batches of qualified magnetic products obtained by the two different methods are subjected to destructive tests on a press respectively, and the strength values ​​of the two batches of qualified magnetic products are obtained and recorded in a table; by comparing the strength values ​​of the two batches of qualified magnetic products, it is found that the average strength value of the qualified products obtained by the pressure test is 2644.0N, and the average strength value of the qualified products obtained by the acoustic method is 2596.6N. It can be determined that the initially determined test pressure will not cause secondary damage, and the initially determined test pressure is determined as the final test pressure.

[0047] A pressure-type magnetic product hidden crack detection device includes a base 1, a conveyor belt 2, a detection platform 3 and a pressure roller 4. The conveyor belt 2 and the pressure roller 4 are arranged above the base 1, and the detection platform 3 is located between the top of the base 1 and the pressure roller 4. The conveyor belt 2 is wound around three pulleys arranged in a triangle. The pulleys are mounted on a mounting plate, and the mounting plate is fixed to a beam erected above the base 1. A conveying guide groove 5 is provided on the top of the base 1. The detection platform 3 is located at the rear end of the conveying guide groove 5. The conveying guide groove 5 is composed of a pair of parallel baffles, and the baffles are fixed to the base 1 by screws. The base 1 is provided with five groups of baffle mounting hole groups, so that the spacing between the two baffles can be changed to accommodate magnetic products of different specifications. A driven conveyor belt is provided in the conveying guide groove 5. The inspection platform 3 includes a platform body 6, two pairs of rollers 7, and a pair of support shafts 8. The top of the platform body 6 is provided with a platform top groove 9 of the same width as the conveying guide groove 5. The support shaft 8 runs across the platform body and is rotatably connected to the platform body 6. One end of the support shaft 8 is provided with an enlarged diameter end, and the other end is positioned by a retaining ring. The rollers 7 are embedded in the bottom of the platform top groove 9, with the top of the rollers 7 protruding above the bottom of the platform top groove 9. The rollers 7 and the support shafts 8 are in rolling contact. The axis of the rollers 7 is perpendicular to the side of the platform body 6, and the lowest point of the pressure roller 4 is located between the two rollers 7. The width of the pressure roller 4 is smaller than the width of the platform top groove 9. The ends of the pressure roller 4 axle are mounted on an axle seat via an eccentric sleeve. The axle seat is mounted on a cantilever, thereby suspended above the inspection platform 3. The cantilever is fixed to the outside of the base 1. By rotating the eccentric sleeve, the height of the pressure roller 4 relative to the inspection platform 3 can be changed, thereby changing the pressure. A pressure sensor 11 is provided at the bottom of the inspection platform 3, and the bottom of the pressure sensor 11 is in contact with the base 3. A pressure display 10 is also installed on the base 1, and the pressure display 10 is electrically connected to the pressure sensor 11. A screening station is provided behind the detection platform 3 to screen out the crushed magnetic products. The screening station is located as a whole in the conveying guide trough 5. The screening station includes a support bar 12. The top surface of the base 1 is hollowed out to form a blanking port 13. The support bar 12 is located at the rear end of the blanking port 13 and is aligned with the top surface of the base 1. The distance between the support bar 12 and the front edge of the blanking port 13 is slightly less than the length of a single magnetic product. A flap 14 is provided at the front edge of the blanking port 13. A rotating shaft is fixed to the front end of the flap 14. One end of the rotating shaft is rotatably connected to the side of the blanking port 13, and the other end of the rotating shaft is fixed to the output end of a swing cylinder. When the swing cylinder is in the retracted state, the flap 14 is in a horizontal state to seal the blanking port 13 and is flush with the top surface of the base 1; when the swing cylinder is in the extended state, the flap 14 flips to a vertical state, so that the blanking port 13 is open. A vibrating plate is provided behind the screening station, a conveying guide groove 5 is still provided on the vibrating plate, and an identification camera is provided above the vibrating plate.

[0048] This pressure-type magnetic product hidden crack detection device operates intermittently under the control of a single-chip microcomputer. Magnetic products are transferred from the grinding machine to the beginning of a conveyor trough 5. Conveyor belt 2 presses against the products, conveying them in steps through friction, with each step equal to the length of the product. Each magnetic product is pressed against another and gradually enters the detection platform 3. There, the entire product is rolled from end to end by pressure wheels 4. Any hidden cracks will be crushed by pressure wheels 4. However, due to the mutual pressure between the front and back of the magnetic products and the restraint of the conveyor trough 5, the broken magnetic products will not disperse temporarily. When the magnetic product is pushed to the screening station, it enters a pause cycle. At this time, the front and rear ends of the magnetic product overlap with the top surface of the base 1 and the support bar 12 at the front edge of the drop port 13 by 1 mm. That is, the front and rear ends of the magnetic product are respectively supported by the support bar 12, and the flap 14 flips over, and the middle part of the magnetic product loses support. If it is a good product, the magnetic product as a whole remains stable because the front and rear ends are still supported. If it is a crushed defective product, the magnetic product cannot maintain its original shape with only the support of the front and rear ends, and it disintegrates. The disintegrated fragments fall from the drop port 13 to the waste conveyor belt below the drop port 13, and are automatically sent to the waste pool through the waste conveyor belt. The flap 14 opens for 0.5 seconds and then flips back to restore. Then the pause cycle ends. The magnetic products screened by the screening station continue to move forward, and after moving out of the screening station, they arrive at the vibrating plate. The magnetic products on the vibrating plate are still driven by the power transmitted by the conveyor belt 2 through the arranged magnetic products. After the vibration of the vibrating plate, some dark cracks appear on the shallow surface of the magnetic products. The defective products that have not been disintegrated at the screening station can be fully disintegrated and identified by the recognition camera, and an alarm is prompted to facilitate subsequent manual sorting.

[0049] Example 2:

[0050] In step 2.5, if the average strength value of the qualified products obtained by the pressure test is 2544.4 N and the average strength value of the qualified products obtained by the acoustic method is 2578.5 N, and the error between the two is within the allowable range of 100 N, it can be determined that the initially determined test pressure will not cause secondary damage, and the initially determined test pressure is determined as the final test pressure. The rest of the process is the same as in Example 1.

[0051] Example 3:

[0052] In step 2.3, select the maximum value of 515N among the recorded strength values ​​and increase it by 15%, that is, 592.3N, as the initial test pressure;

[0053] Step 2.4. 100 magnetic products were selected and placed one by one on the pressure-type magnetic product hidden crack detection device. Each magnetic product was pressure-tested at an initial test pressure of 592.3N. After the test, 88 magnetic products remained intact and were determined to be good products. Another 88 good magnetic products were selected from the same batch of magnetic products using the acoustic method.

[0054] In step 2.4, it was found that the average strength value of the qualified products obtained by the pressure test was 2266N, while the average strength value of the qualified products obtained by the acoustic method was 2473N. The strength value of the qualified products obtained by the pressure test was low and the error exceeded the allowable range of 100N. It can be determined that the initially determined test pressure caused secondary damage to the magnetic product. The initial test pressure was reselected, and the maximum strength value of 515N obtained in step 2.3 was increased by 10%, that is, 566.5N as the initial test pressure. Steps 2.4 and 2.5 were repeated. It was found that the average strength value of the qualified products obtained by the pressure test was 2551N. 566.5N was determined as the final test pressure. The rest of the process was the same as in Example 1.

Claims

1. A method for detecting dark cracks in magnetic products, characterized by The following steps are involved: Step 1. Make a pressure-type magnetic product hidden crack detection device; Step 2. Select several defective magnetic products with dark crack defects and determine the detection pressure of the pressure-type magnetic product dark crack detection device by pressure verification on the defective products. This step includes: selecting defective magnetic products with dark crack defects by the acoustic method; Defective magnetic products are pressurized one by one on a press for destructive testing, and the pressure at which the defective magnetic products break is used as the strength value, which is recorded in a table; the maximum value of the recorded strength values ​​is selected, and the value is increased by 10%-15% as the initial test pressure; a number of magnetic products are selected and placed one by one on the pressure-type magnetic product hidden crack detection device, and the magnetic products are pressurized one by one with the same initial test pressure, and a number of good magnetic products that remain intact after the test are selected; the same number of good magnetic products are selected from the same batch of magnetic products by using the acoustic method; the two batches of good magnetic products are respectively subjected to destructive testing on the press, and the strength values ​​of the two batches of good magnetic products are obtained and recorded in a table; the strength values ​​of the two batches of good magnetic products are compared to determine whether the initial test pressure should be used as the final test pressure; Step 3. Input the product to be inspected into the pressure-type magnetic product hidden crack detection device; Step 4. Perform a pressure test on the product to be tested at the test pressure obtained in step 1; Step 5. The products to be inspected that are damaged under the inspection pressure are sorted out as defective products.

2. The method for detecting hidden cracks in magnetic products according to claim 1 is characterized in that in step 2, when comparing the strength values ​​of two batches of qualified magnetic products, if it is found that the strength value of the qualified product obtained by the pressure test is greater than or equal to the strength value of the qualified product obtained by the acoustic method, or the strength value of the qualified product obtained by the pressure test is less than the strength value of the qualified product obtained by the acoustic method, but the error is within the allowable range, it can be determined that the initial detection pressure will not cause secondary damage, and the initial detection pressure is determined as the final detection pressure; if it is found that the strength values ​​of the qualified product obtained by the pressure test and the qualified product obtained by the acoustic method are low and the error exceeds the allowable range, it can be determined that the initial detection pressure has caused secondary damage to the magnetic product, the initial detection pressure is reselected, and the selection, destructive testing and strength value comparison of the two batches of qualified magnetic products are repeated.

3. The method for detecting hidden cracks in magnetic products according to claim 1, characterized in that The defective products picked out in step 5 are automatically sent to the waste pool.

4. The method for detecting hidden cracks in magnetic products according to claim 1, 2 or 3, characterized in that The pressure-type magnetic product hidden crack detection device is arranged between the grinder and the cleaning machine.

5. A pressure-type magnetic product hidden crack detection device according to any one of claims 1 to 4, characterized in that It includes a base, a conveyor belt, a detection platform and a pressure wheel. The conveyor belt and the pressure wheel are arranged above the base, and the detection platform is located between the base and the pressure wheel.

6. The pressure-type magnetic product hidden crack detection device according to claim 5, wherein the characteristic detection A pressure sensor is provided at the bottom of the carrier.

7. The pressure-type magnetic product hidden crack detection device according to claim 6 is characterized in that The device also includes a pressure display, which is electrically connected to the pressure sensor.

8. The pressure-type magnetic product hidden crack detection device according to claim 5 is characterized by A conveying guide groove is provided on the top of the base, and the detection platform is located on the path of the conveying guide groove.

9. The pressure-type magnetic product hidden crack detection device according to claim 8 is characterized in that The detection platform includes a platform body, a roller and a support shaft. The top of the platform body is provided with a platform top groove with the same width as the conveying guide groove. The support shaft runs across the platform body and is rotatably connected to the platform body. The roller is embedded in the bottom of the platform top groove. The top of the roller is higher than the bottom of the platform top groove. The roller is in rolling contact with the support shaft.

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