Wear detection method and device for exhaust plate of aluminum product of automobile parts

Abstract

The present application relates to a wear detection method and device for exhaust plates of aluminum products of automotive parts, the method includes the following steps: the portion of the aluminum product corresponding to the exhaust plate is used as a test portion; the thickness of a set position on the test portion is measured to obtain multiple thickness measurement values; the multiple thickness measurement values ​​are compared one by one with multiple preset thickness comparison values ​​corresponding to the set positions, the thickness measurement value is subtracted from the corresponding thickness comparison value to obtain a comparison difference, and a comparison difference sum value of the absolute values ​​of the multiple comparison difference values ​​is obtained. If the comparison difference sum value is greater than the preset reference sum value, it indicates that the exhaust plate is severely worn; the pre-calibrated base point on the test portion is located, and the area within the range set by the base point is taken as the detection area; the shape of the detection area is overlapped with the preset detection shape, and the area of ​​the detection area outside the overlap is identified. If the area of ​​the area is greater than the preset reference area, it indicates that the exhaust plate is severely worn. The present application makes it easier to detect whether the exhaust plate is eroded.

Description

Technical Field

[0001] The present application relates to the field of exhaust plate detection, and in particular to a wear detection method and a detection device for exhaust plates of aluminum products of automobile parts. Background Art

[0002] At present, high-speed aluminum liquid forming products are widely used in aluminum products for automotive parts. The aluminum liquid is injected from one end of the mold to the other end of the mold. The other end of the mold is also connected to an exhaust plate to discharge the gas retained inside the mold when the aluminum liquid is not injected. The exhaust plate is a part that discharges the gas inside the mold. Its working principle is that when the aluminum liquid fills the mold, the gas in the mold cavity is pushed by the aluminum liquid, passes through the exhaust channel, and finally discharged from the mold from the exhaust plate.

[0003] Existing exhaust plates are generally wavy in shape, which have the advantages of simple structure and easy repair. However, when the aluminum liquid fills the exhaust plate, the aluminum liquid speed is high and the exhaust plate is severely eroded. Therefore, it is often necessary to inspect the exhaust plate. If the exhaust plate is damaged, it needs to be replaced. In order to inspect the exhaust plate, the exhaust plate needs to be removed and scanned and identified using a high-precision and expensive 3D scanner.

[0004] With respect to the above-mentioned related technologies, the inventor believes that there are defects in that the exhaust plate needs to be removed for testing and expensive equipment is required for testing. Summary of the invention

[0005] In order to make it easier to detect whether an exhaust plate is eroded, the present application provides a wear detection method for an exhaust plate of an aluminum product that is an automotive component.

[0006] In the first aspect, the present application provides a wear detection method for an exhaust plate of an aluminum product of an automobile component, which adopts the following technical solution:

[0007] A wear detection method for an exhaust plate of an aluminum product of an automobile component comprises the following steps:

[0008] S1: produce a plate-shaped aluminum product, and remove the portion of the aluminum product corresponding to the exhaust plate as the test portion;

[0009] S2: simultaneously measuring the thickness of a set position on the test part to obtain a plurality of thickness measurement values;

[0010] S3: Compare the multiple thickness measurement values ​​with the multiple preset thickness comparison values ​​corresponding to the set positions one by one, subtract the corresponding thickness comparison value from the thickness measurement value to obtain a comparison difference value, and a comparison difference sum value of the absolute values ​​of the multiple comparison difference values. If the comparison difference sum value is greater than the preset reference sum value, it indicates that the exhaust plate is seriously worn;

[0011] S4: locating a pre-calibrated base point on the test site, and taking an area within a set range of the base point as a detection area; and,

[0012] S5: Overlapping the shape of the detection area with a preset detection shape, identifying the area of ​​the detection area outside the overlap, and if the area is larger than a preset reference area, it indicates that the exhaust plate is severely worn.

[0013] By adopting the above technical solution, the exhaust plate is not inspected directly, but the inspection part corresponding to the exhaust plate on the aluminum product is inspected. By detecting whether the thickness at each position on the inspection part is abnormal and detecting whether the shape of the inspection part is abnormal, it is indirectly judged whether the exhaust plate is severely worn. The state of the exhaust plate can be known without disassembling the exhaust plate for inspection, making it easier to detect whether the exhaust plate is eroded.

[0014] Preferably, S2 also includes:

[0015] S21: using two sets of displacement sensors on both sides of the test site to measure the distance between the surfaces of the test site;

[0016] S22: Multiple displacement sensors in each group of displacement sensors are located in the same working plane and are distributed in a matrix, a measuring rod with an end abutting against the surface of the test part is slidably connected to the displacement sensor, the positions of the two groups of displacement sensors are relatively fixed and are arranged in a mirror-symmetrical manner, and the area between the two groups of displacement sensors is the test area; and,

[0017] S23: the test part slides from one side of the test area until it completely enters the test area for testing, and after the test is completed, the test part slides out from the other side of the test area.

[0018] By adopting the above technical solution, the two sets of displacement sensors can measure the thickness of the detection part after cooperating with each other. At the same time, when the test part is displaced between the two sets of displacement sensors, the end of the measuring rod can smooth out the tiny burrs on its surface, so that the part with tiny burrs can be accurately measured by other displacement sensors.

[0019] Preferably, S3 also includes:

[0020] S31: presetting a correction value that is always greater than 0 for each of the comparison differences;

[0021] S32: after calculating the latest comparison difference, updating the correction value, wherein the correction value and the absolute value of the comparison difference are inversely correlated; and

[0022] S33: taking the result of multiplying the correction value and the comparison difference as a new comparison difference.

[0023] By adopting the above technical solution, the measurement error caused by the slip of the measuring rod on the displacement sensor is corrected by the correction value. Generally, the measurement error on the measuring rod will accumulate, and the correction value can reduce the error according to the slip length of the measuring rod, which is conducive to providing measurement accuracy.

[0024] Preferably, the S4 also includes:

[0025] The part with basic functions on the aluminum product is a base part, and the base point is pre-set at a fixed position on the edge of the base part close to the test part.

[0026] By adopting the above technical solution, it is helpful to quickly determine the range of the test part through the preset base points.

[0027] Preferably, the S5 further includes:

[0028] S51: The area covered by the preset detection shape includes a plurality of displacement sensors both inside and outside the area;

[0029] S52: the area of ​​the region is sensed by a displacement sensor outside the region covered by the detection shape and indirectly calculated; and,

[0030] S53: The area of ​​the region is set in positive correlation with the number of displacement sensors outside the coverage area of ​​the triggered detection shape.

[0031] By adopting the above technical solution, the area of ​​the region can be roughly measured by the displacement sensor without setting up additional sensors, which is convenient and practical.

[0032] Preferably, the S5 further includes:

[0033] S51: using a color mask corresponding to an area covered by a preset detection shape, wherein the color of the color mask is different from the color of the detection part;

[0034] S52: photographing the portion of the test part that is not blocked by the color mask, the area of ​​the unblocked portion being the area of ​​the region, the color mask being located between a photographing point and the test part, and the photographing point being opposite to the color mask; and

[0035] S53: Calculate the size of the area.

[0036] By adopting the above technical solution, the area of ​​the area can be measured more accurately through the camera.

[0037] In the second aspect, the present application provides a wear detection device for an exhaust plate of an aluminum product of an automobile component, which adopts the following technical solution:

[0038] A wear detection device for exhaust plates of aluminum products of automobile parts, used for detecting plate-shaped aluminum products, the portion of the aluminum product corresponding to the exhaust plate being a test portion, the device comprising two groups of displacement sensors arranged on both sides of the test portion, a plurality of displacement sensors in each group of displacement sensors being located on the same working plane and distributed in a matrix, a measuring rod having an end abutting against the surface of the test portion being slidably connected to the displacement sensor, the positions of the two groups of displacement sensors being relatively fixed and being arranged in a mirror-symmetrical manner, the area between the two groups of displacement sensors being a test area, the area of ​​the test area being larger than the area of ​​the test portion;

[0039] The displacement sensor is electrically connected to a processor, and the processor is electrically connected to an alarm.

[0040] By adopting the above technical scheme, the exhaust plate is not directly inspected, but the inspection part corresponding to the exhaust plate on the aluminum product is inspected. The two sets of displacement sensors can measure the thickness of the inspection part after cooperating with each other, providing a hardware basis for detecting whether the thickness of each position on the inspection part is abnormal. When the test part is displaced between the two sets of displacement sensors, the end of the measuring rod can also smooth out the tiny burrs on its surface, so that the part with tiny burrs can be accurately measured by other displacement sensors; it can also provide a hardware basis for indirectly judging whether the exhaust plate is severely worn by detecting whether the shape of the inspection part is abnormal through the displacement sensor. The state of the exhaust plate can be known without disassembling the exhaust plate for inspection, making it easier to detect whether the exhaust plate is eroded.

[0041] Preferably, a color mask is placed on the test site, and the color of the color mask is different from the color of the test site;

[0042] A camera facing the test part is arranged in the middle of each group of displacement sensors, and the camera is electrically connected to the processor.

[0043] By adopting the above technical solution, a hardware foundation is provided for more accurately measuring the area through the camera.

[0044] Preferably, an elastic crimping net is provided at one end of the displacement sensor away from the test site, and a middle portion of the elastic crimping net is fixedly connected to a housing of the displacement sensor to press the measuring rod onto the test site.

[0045] By adopting the above technical solution, it is helpful to reduce the position floating of the measuring rod on the displacement sensor after multiple sliding, thereby reducing the error.

[0046] Preferably, the end of the measuring rod abutting the test part is rotatably connected with an abutment ball.

[0047] By adopting the above technical solution, the abutment ball can make the measuring rod slide more smoothly on the surface of the test part, preventing the measuring rod from getting stuck on the test part or increasing additional measurement errors.

[0048] The beneficial effects of this application include at least:

[0049] 1. Detect the detection part corresponding to the exhaust plate on the aluminum product, and indirectly judge whether the exhaust plate is seriously worn by detecting whether the thickness of each position on the detection part is abnormal, and detecting whether the shape of the detection part is abnormal. The state of the exhaust plate can be known without disassembling the exhaust plate for detection;

[0050] 2. The area of ​​the area can be roughly measured through the displacement sensor without setting up additional sensors, which is convenient and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a method flow chart of steps S1-S5 in the wear detection method for exhaust plates of aluminum products of automotive parts in the present application.

[0052] Figure 2 It is a structural diagram of the aluminum product of this application.

[0053] Figure 3 This is a structural diagram of a set of displacement sensors.

[0054] Figure 4 This is a structural diagram of two sets of displacement sensors measuring aluminum products.

[0055] Figure 5 This is a structural diagram of aluminum products captured by a camera.

[0056] Figure 6 This is a structural diagram of the camera capturing the color mask covering the aluminum product.

[0057] Figure numerals: 1. Aluminum product; 2. Test part; 3. Displacement sensor; 4. Measuring rod; 5. Color shield; 6. Camera; 7. Processor; 8. Alarm; 9. Fill light; 10. Elastic crimping net; 11. Abutment ball. DETAILED DESCRIPTION

[0058] The following is combined with Figure 1-6 This application is described in further detail.

[0059] The embodiments of the present application are further described in detail below in conjunction with the drawings in the specification.

[0060] The present application embodiment discloses a wear detection method for an exhaust plate of an aluminum product of an automobile component, such as Figure 1 As shown, the following steps are included:

[0061] S1: produce a plate-shaped aluminum product 1, and remove the portion of the aluminum product 1 corresponding to the exhaust plate as the test portion 2. Figure 2 As shown, the aluminum product 1 is in the shape of a flat plate, the test part 2 is on one side thereof, and is located at the exhaust plate connected to the mold for generating the aluminum product 1. The shape of the inner wall of the exhaust plate can be a grid type or a wave type, and the length of the wave stripes is perpendicular to the exhaust direction.

[0062] S2: Simultaneously measure the thickness of the set position on the test part 2 to obtain multiple thickness measurement values. S2 also includes: S21: Use two sets of displacement sensors 3 on both sides of the test part 2 to measure the distance between the surfaces of the test part 2. Figure 3 and Figure 4 As shown, S22: multiple displacement sensors 3 in each group of displacement sensors 3 are located in the same working plane and are distributed in a matrix. The displacement sensors 3 are slidably connected with measuring rods 4 whose ends abut the surface of the test part 2. The positions of the two groups of displacement sensors 3 are relatively fixed and are arranged in a mirror-symmetrical manner. The area between the two groups of displacement sensors 3 is the test area. The displacement sensor 3 is also called a linear sensor, which is a linear device of metal induction. The displacement sensor 3 can be divided into two types: analog and digital. The commonly used displacement sensors 3 are mostly analog structural types, including potentiometer displacement sensors 3, inductive displacement sensors 3, capacitive displacement sensors 3, eddy current displacement sensors 3, Hall displacement sensors 3, etc. An important advantage of the digital displacement sensor 3 is that it is easy to send the signal directly to the computer system. The displacement sensor 3 has a fixed housing and a measuring rod 4 slidably connected to the housing. The data output by the displacement sensor 3 represents the sliding position of the measuring rod 4 or the distance from the initial position. The measuring rods 4 on each group of displacement sensors 3 are parallel to each other. When pressed on the test part 2 at the same time, the surface shape of the test part 2 is different, and the displacement of the measuring rod 4 is also different. The number of displacement sensors 3 in each group of displacement sensors 3 is the same, and the displacement sensors 3 in one group correspond to the displacement sensors 3 in the other group one by one. In the initial state, the displacement sensors 3 in one group and the corresponding displacement sensors 3 in the other group, the ends of the two measuring rods 4 are in contact, and the thickness is 0 at this time. If the displacement of the measuring rod 4 of one sensor is 1mm, and the displacement of the measuring rod 4 of the other corresponding sensor is 2mm, then the thickness is 3mm. And, S23: the test part 2 slides from one side of the test area until it enters the test area completely, and then the test is performed. After the test is completed, the test part 2 slides out from the other side of the test area. When the test part 2 is displaced between the two groups of displacement sensors 3, the ends of the measuring rods 4 can also smooth out the tiny burrs on its surface, so that the parts with tiny burrs can be accurately measured by other displacement sensors 3.

[0063] S3: Compare multiple thickness measurement values ​​with multiple preset thickness comparison values ​​corresponding to the set positions one by one, subtract the corresponding thickness comparison value from the thickness measurement value to obtain the comparison difference value, and the comparison difference sum value of the absolute values ​​of the multiple comparison difference values. If the comparison difference sum value is greater than the preset reference sum value, it indicates that the exhaust plate is seriously worn. For example, the thickness measurement values ​​are measured as 3mm, 4mm, 3.5mm, 3.75mm and 3.6mm, respectively, and the thickness comparison values ​​are: 3mm, 3.8mm, 3.4mm, 3.7mm and 3.7mm, respectively. The comparison difference values ​​are: 0mm, 0.2mm, 0.1mm, 0.05mm and -0.1mm, respectively, the comparison difference sum value is 0.45mm, and the reference sum value is 1mm. The comparison difference sum value is less than the reference sum value, so the exhaust plate is not seriously worn. The thickness measurement values ​​are 4mm, 4mm, 4.5mm, 3.75mm and 3.6mm respectively, while the thickness comparison values ​​are 3mm, 3.8mm, 3.4mm, 3.7mm and 3.7mm respectively. The comparison difference values ​​are 1mm, 0.2mm, 1.1mm, 0.05mm and -0.1mm respectively. The comparison difference sum is 2.45mm, and the reference sum is 1mm. The comparison difference sum is greater than the reference sum, so the exhaust plate is seriously worn. S3 also includes: S31: preset a correction value that is always greater than 0 for each comparison difference. S32: after calculating the latest comparison difference, update the correction value, and the absolute value of the correction value and the comparison difference value are inversely correlated. And, S33: the result of multiplying the correction value by the comparison difference is used as the new comparison difference. For example, the correction value may be 1, 0.95, 1.05, 1.01 and 0.99. If the comparison difference value increases by 1, the corresponding correction value decreases by 0.1. If the comparison difference value decreases by 1, the corresponding correction value increases by 0.06.

[0064] S4: Locate the pre-calibrated base point on the test part 2, and take the area within the range of the base point setting as the detection area. Among them, the part with basic functions on the aluminum product 1 is the base part, and the base point is pre-set at a fixed position on the edge of the base part close to the test part 2, which is conducive to quickly determining the range of the test part 2 through the preset base point.

[0065] as well as,

[0066] S5: Overlap the shape of the detection area with the preset detection shape, identify the area of ​​the detection area outside the overlap, and if the area is larger than the preset reference area, it indicates that the exhaust plate is severely worn. S5 also includes: S51: The area covered by the preset detection shape contains multiple displacement sensors 3 both inside and outside. S52: The area of ​​the area is sensed by the displacement sensors 3 outside the area covered by the detection shape and calculated indirectly. And, S53: The area of ​​the area is positively correlated with the number of displacement sensors 3 outside the area covered by the triggered detection shape. In this way, the area of ​​the area can be roughly measured by the displacement sensor 3 without setting up additional sensors, which is convenient and practical.

[0067] In other cases, such as Figure 5 and Figure 6 As shown, for example, when it is inconvenient to set too many displacement sensors 3, S5 also includes: S51: using a color mask 5 corresponding to the area covered by the preset detection shape, the color of the color mask 5 is different from the color of the detection part. For example, the aluminum product 1 is silvery white, and a black or yellow color mask 5 can be used. S52: photographing the part of the test part 2 that is not blocked by the color mask 5, the area of ​​the unblocked part is the regional area, the color mask 5 is located between the shooting point and the test part 2, and the shooting point is opposite to the color mask 5. And, S53: calculating the size of the regional area. Let the color mask 5 block the silvery white aluminum product 1. If it can be completely blocked, it means that the exhaust plate is not seriously worn. If the color mask 5 fails to block the silvery white aluminum product 1, and then uses the camera 6 to shoot, it is convenient for the camera 6 to measure the regional area more accurately, thereby facilitating a more accurate judgment of whether the exhaust plate is seriously worn.

[0068] The implementation principle is: detect the detection part on the aluminum product 1 corresponding to the exhaust plate, and let the two sets of displacement sensors 3 in mirror symmetry cooperate with each other to measure the thickness of the detection part. Do not directly detect the exhaust plate, but indirectly judge whether the exhaust plate is seriously worn by detecting whether the thickness of each position on the detection part is abnormal, and whether the shape of the detection part is abnormal. In order to compensate for the error of the displacement sensor 3 itself, the measurement error caused by the slip of the measuring rod 4 is corrected by the correction value, which is conducive to providing measurement accuracy. Therefore, the state of the exhaust plate can be accurately known without disassembling the exhaust plate for detection, making it easier to detect whether the exhaust plate is eroded.

[0069] The present application also discloses a wear detection device for an exhaust plate of an aluminum product of an automobile component, such as Figure 5 and Figure 6As shown, it is used to detect a plate-shaped aluminum product 1, and the part of the aluminum product 1 corresponding to the exhaust plate is the test part 2. The device includes two groups of displacement sensors 3 arranged on both sides of the test part 2. The multiple displacement sensors 3 in each group of displacement sensors 3 are located in the same working plane and are distributed in a matrix. A measuring rod 4 with an end abutting the surface of the test part 2 is slidably connected to the displacement sensor 3. The positions of the two groups of displacement sensors 3 are relatively fixed and are arranged in a mirror symmetry. The area between the two groups of displacement sensors 3 is the test area, and the area of ​​the test area is larger than the area of ​​the test part 2.

[0070] Each displacement sensor 3 is electrically connected to a processor 7 directly or through a communication protocol. The processor 7 can be an MCU single-chip computer. The processor 7 is electrically connected to an alarm 8. The alarm 8 can be a self-driven sound and light alarm. The displacement sensor 3 sends an electrical signal to the processor 7, which is the displacement length of the measuring rod 4. A color mask 5 is placed on the test part 2. Preferably, the shape of the color mask 5 is adapted to the shape of the test part 2 produced by a normal exhaust plate, and the color of the color mask 5 is different from the color of the detection part. A camera 6 facing the test part 2 is arranged in the middle of each group of displacement sensors 3. The camera 6 is electrically connected to the processor 7. A fill light 9 can be arranged around the camera 6. The fill light 9 fills in the light for the camera 6 when the light is insufficient. The above-mentioned devices, electronic components or circuit modules provide a hardware basis for more accurately measuring the area of ​​the area through the camera 6.

[0071] An elastic crimping net 10 is provided at one end of the displacement sensor 3 away from the test part 2. The elastic crimping net 10 can be a rubber net or an elastic nylon net. The elastic crimping net 10 is bonded to the end of the measuring rod 4 away from the test part 2. The elastic crimping net 10 is always in a stretched state, and the elastic crimping net 10 allows the measuring rod 4 to have a tendency to press the test part 2. The middle part of the elastic crimping net 10 is fixedly connected to the outer shell of the displacement sensor 3 to press the measuring rod 4 on the test part 2, which is conducive to reducing the position floating of the measuring rod 4 on the displacement sensor 3 after multiple slips, thereby reducing the error. The end of the measuring rod 4 abutting the test part 2 is rotatably connected with an abutment ball 11, and the abutment ball 11 and the rotating structure can constitute a universal roller. The abutment ball 11 can allow the measuring rod 4 to slide more smoothly on the surface of the test part 2, preventing the measuring rod 4 from getting stuck on the detection part or increasing additional measurement errors.

[0072] The implementation principle is: instead of directly testing the exhaust plate, the detection part corresponding to the exhaust plate on the aluminum product 1 is detected. The two sets of displacement sensors 3 can measure the thickness of the detection part after cooperating with each other, providing a hardware basis for detecting whether the thickness of each position on the detection part is abnormal. When the test part 2 is displaced between the two sets of displacement sensors 3, the end of the measuring rod 4 can also smooth out the tiny burrs on its surface, so that the parts with tiny burrs can be accurately measured by other displacement sensors 3 after preliminary cleaning. The device provides a hardware basis for indirectly judging whether the exhaust plate is severely worn by detecting whether the shape of the detection part is abnormal through the displacement sensor 3. The exhaust plate state can be known without disassembling the exhaust plate for testing, making it easier to detect whether the exhaust plate is eroded.

[0073] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A wear detection method for an exhaust plate of an aluminum product of an automobile component, characterized in that: The steps include: S1: producing a plate-shaped aluminum product (1), and removing a portion of the aluminum product (1) corresponding to the exhaust plate as a test portion (2); S2: simultaneously measuring the thickness of a set position on the test part (2) to obtain a plurality of thickness measurement values; S3: Compare the multiple thickness measurement values ​​with the multiple preset thickness comparison values ​​corresponding to the set positions one by one, subtract the corresponding thickness comparison value from the thickness measurement value to obtain a comparison difference value, and a comparison difference sum value of the absolute values ​​of the multiple comparison difference values. If the comparison difference sum value is greater than the preset reference sum value, it indicates that the exhaust plate is seriously worn; S4: locating a pre-calibrated base point on the test part (2), and taking an area within a set range of the base point as a detection area; as well as, S5: Overlapping the shape of the detection area with a preset detection shape, identifying the area of ​​the detection area outside the overlap, and if the area is larger than a preset reference area, it indicates that the exhaust plate is severely worn.

2. The method according to claim 1, characterized in that: The S2 also includes: S21: using two sets of displacement sensors (3) on both sides of the test part (2) to measure the distance between the surfaces of the test part (2); S22: The plurality of displacement sensors (3) in each group of displacement sensors (3) are located on the same working plane and are arranged in a matrix, a measuring rod (4) whose end abuts against the surface of the test part (2) is slidably connected to the displacement sensor (3), the positions of the two groups of displacement sensors (3) are relatively fixed and are arranged in a mirror-symmetrical manner, and the area between the two groups of displacement sensors (3) is the test area; and, S23: The test part (2) slides from one side of the test area until it completely enters the test area and then performs a test. After the test is completed, the test part (2) slides out from the other side of the test area.

3. The method according to claim 1, characterized in that: The S3 also includes: S31: presetting a correction value that is always greater than 0 for each of the comparison differences; S32: after calculating the latest comparison difference, updating the correction value, wherein the correction value and the absolute value of the comparison difference are inversely correlated; and S33: taking the result of multiplying the correction value and the comparison difference as a new comparison difference.

4. The method according to claim 1, characterized in that: The S4 also includes: The portion of the aluminum product (1) having a basic function is a base portion, and the base point is pre-set at a fixed position on the edge of the base portion close to the test portion (2).

5. The method according to claim 1, characterized in that: The S5 also includes: S51: The area covered by the preset detection shape includes a plurality of displacement sensors (3) both inside and outside the area covered by the preset detection shape; S52: the area of ​​the region is sensed by a displacement sensor (3) outside the region covered by the detection shape and indirectly calculated; and, S53: The area of ​​the region is set in a positive correlation with the number of displacement sensors (3) outside the coverage area of ​​the detection shape that are triggered.

6. The method according to claim 1, characterized in that: The S5 also includes: S51: using a color mask (5) corresponding to an area covered by a preset detection shape, wherein the color of the color mask (5) is different from the color of the detection part; S52: photographing the portion of the test part (2) that is not blocked by the color mask (5), the area of ​​the unblocked portion being the area of ​​the region, the color mask (5) being located between a photographing point and the test part (2), and the photographing point being directly opposite to the color mask (5); and, S53: Calculate the size of the area.

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