Tool plane scribed line automatic detection device and method based on image recognition

Abstract

The invention provides a tool plane scribed line automatic detection device and method based on image recognition. The device comprises a PH20 measuring base and an automatic detection assembly. The PH20 measuring base is installed on a Z-axis transmission device of a three-coordinate measuring machine, and the automatic detection assembly is connected with the PH20 measuring base. Wherein the automatic detection assembly comprises a wireless transmission module, an industrial camera module, a fixed shell, a pen point, a marking pen, a buffer spring and a fixing screw; wherein the wireless transmission module and the industrial camera module are installed in a reserved space in the fixed shell in advance, the fixed shell is fixed to the measuring rod through the fixing screw, a pen point is installed in a reserved hole in the bottom of the marking pen, and the marking pen is filled with red ink and then is connected with the buffer spring together. The marking pen is axially centered with the measuring rod and installed in a reserved space close to the bottom in the middle of the fixing shell, the marking pen is fixed through the fixing screw, and a groove is formed in the side face of the marking pen to ensure that the marking pen cannot be disengaged after the screw is tightened and can also compress the buffer spring in the Z direction.

Description

Technical Field

[0001] The present application belongs to the technical field of digital detection of three-dimensional coordinate measuring machines, and specifically relates to an automatic detection device and method for tooling plane marking lines based on image recognition. Background Art

[0002] Tooling markings are a series of grooves with smaller depth and width, mainly including part outlines, milling lines, hole center cross lines, etc. They are used to ensure the correctness of the product outline or the position and shape of the precision holes when using tooling to process products; at the same time, the red marks of unqualified points also provide the correct basis for workers to repair the markings, so the accuracy of tooling markings is an important factor in ensuring product quality.

[0003] Faced with the grim situation of increasing production, the traditional manual marking and detection methods are inefficient and cannot be quantitatively judged, so the precise and rapid detection technology of tooling engraving lines urgently needs to be broken through. The traditional detection method is to manually spread red bile powder on the stylus of the three-dimensional coordinate measuring machine in advance. When the stylus touches the theoretical position of the engraving line extraction point, red bile powder marks will be left on the surface of the tooling. The measurement personnel judge whether the red mark is on the actual engraving line by naked eye observation, and then qualitatively infer the qualification degree of the engraving line. The advantage of the traditional method is that it can be applied to tooling engraving lines on complex surfaces, but its disadvantages are also obvious, mainly the following three points:

[0004] 1. The application of red bile powder needs to be done manually, which is time-consuming, laborious and uneven. The red bile powder on the probe is limited, and the measurement personnel need to observe and apply it at any time to avoid leaving no mark due to insufficient red bile powder when touching a certain point; in addition, the manual application of red bile powder causes each mark point to be of different sizes, and too large or too small will affect the result judgment. This work is completely dependent on the measurement personnel's operating experience.

[0005] 2. The qualified judgment of the tooling marking line is completely dependent on the human eye's judgment of the relative position relationship between the red mark and the actual marking line. This method is inefficient and the judgment result is unstable. Whether the tooling marking line is qualified or not depends entirely on the operator's work experience, the clarity of the red mark, the depth and thickness of the marking line, and the intensity of light at the time and other uncontrollable factors. Summary of the invention

[0006] Purpose of the invention: To provide an automatic detection device and method for tooling plane engraving lines based on image recognition, wherein the automatic detection device containing a high-precision industrial camera and a marking pen replaces the stylus in situ on the PH20 measuring seat and fixes it on the measuring rod, so that the marking pen and the measuring rod remain coaxially aligned, and the automatic detection device is controlled by a three-coordinate measuring machine to perform processes such as lowering the height to make marks and raising the height to take images one by one at the theoretical positions extracted in advance, and the images are transmitted to the computer through a wireless transmission module. The set algorithm can quickly parse the center point of the red marked pixel group and the edge contour of the nearby engraved lines, and finally convert the distance between the center point of the red marked pixel group and the edge of the engraved lines into the actual size through the number of pixels. The above process can ensure that the automatic detection device completes the engraved line detection task while running continuously until all the theoretical positions extracted in advance are marked.

[0007] In a first aspect, the present application provides an automatic detection device for tooling plane marking lines based on image recognition, the device comprising a PH20 measuring head and an automatic detection component; the PH20 measuring head is installed on a Z-axis transmission device of a three-dimensional coordinate measuring machine, and the automatic detection component is connected to the PH20 measuring head;

[0008] Wherein, the automatic detection component includes a wireless transmission module, an industrial camera module, a fixed housing, a pen tip, a marking pen, a buffer spring, and a fixing screw;

[0009] Among them, the wireless transmission module and the industrial camera module are pre-installed in the reserved space inside the fixed shell. The fixed shell is fixed to the measuring rod by fixing screws. The pen tip is installed in the reserved hole at the bottom of the marking pen. After the marking pen is filled with red ink, it is aligned with the measuring rod axially and installed in the reserved space at the bottom of the middle of the fixed shell together with the buffer spring, and the marking pen is fixed with fixing screws. There are grooves on the side of the marking pen to ensure that the marking pen will not fall out after the screws are tightened, and the buffer spring can also be compressed along the Z direction.

[0010] Preferably, the measuring needle needs to be removed in advance before the fixed housing is fixed to the measuring rod by the fixing screws.

[0011] Preferably, the fixed housing includes an industrial camera cabin, an industrial camera lens cabin, screw fixing holes, a marking pen and buffer spring cabin, a measuring rod fixing cabin, a wireless transmission module cabin, and a measuring rod limiting hole.

[0012] Preferably, the industrial camera cabin is designed according to the size of the industrial camera module and the industrial camera module is installed and packaged before use, while ensuring that the lens of the industrial camera module is vertically downward and within the industrial camera lens cabin. The two screw fixing holes at the lower end are used to fix the marking pen and the buffer spring, and the two screw fixing holes at the upper end are used to fix the fixed measuring rod in the measuring rod fixing cabin.

[0013] Preferably, the marking pen and buffer spring can accommodate the marking pen and buffer spring and ensure that they can move vertically up and down inside. The marking pen and buffer spring compartment is not connected to the measuring rod fixing compartment to ensure that the position of the automatic detection device along the Z item is fixed.

[0014] Preferably, the wireless transmission module cabin is designed according to the size of the wireless transmission module and the wireless transmission module is installed and packaged before use. The measuring rod limit hole uses a hole with the same outer diameter as the measuring rod to limit the X and Y direction degrees of freedom of the automatic detection device.

[0015] In a second aspect, the present application also provides a method for automatically detecting tooling plane marking lines based on image recognition, the method comprising the following steps:

[0016] Step 1: Operate the coordinate measuring machine to return the PH20 measuring head to the origin position of the coordinate measuring machine;

[0017] Step 2: Use the pre-set PC-DMIS program to let the ruby ​​tip touch the standard ball with a pre-calibrated diameter to verify whether the accuracy of the coordinate measuring machine meets the expectations;

[0018] Step 3: Remove the probe, pass the measuring rod through the measuring rod limit hole and the measuring rod fixing cabin in sequence, and tighten it with screws to ensure that the automatic detection device will not loosen. At the same time, ensure that the measuring rod reaches the bottom of the measuring rod fixing cabin to ensure that the Z-axis height is fixed;

[0019] Step 4: Fill the marker pen with red ink, put the buffer spring and fixed marker pen into the marker pen and buffer spring compartment in turn, and tighten them with screws to ensure that the buffer spring and fixed marker pen will not fall out completely;

[0020] Step 5: Turn on the wireless transmission module and industrial camera module to confirm whether the connection with the computer is normal;

[0021] Step 6: Use the pre-set PC-DMIS program to let the pen tip touch the calibration plate with a scale, take an image through the industrial camera module and send it to the computer, confirm that the scale base k is correct and the mark center falls on the center line of the calibration plate, which means that the automatic detection device is considered to have normal accuracy and can be used; the scale base k is the size of each pixel at a unit distance;

[0022] Step 7: Use a height gauge to measure the height of the tooling to be tested on the measuring machine platform, and adjust the safety plane height h in the PC-DMIS program to ensure that the pen tip will not be over-pressed to cause damage to the equipment;

[0023] Step 8: Call the pre-programmed PC-DMIS line measurement program for the tooling. The three-dimensional coordinate measuring machine will make the pen tip drop to touch the tooling surface at each pre-extracted theoretical position, leaving a red mark, and then lift it back to the safe plane height and start the industrial camera module to capture the image of the current part.

[0024] Step 9: The industrial camera module sends the image to the computer. The set algorithm first extracts the pixels of the red marked area, calculates all the points of the outermost contour of the red marked area, and randomly selects a point on the outermost contour, calculates the distance to other points on the outermost contour and finds the maximum value. The midpoint of the line connecting the maximum value position and the point is the center of the circle O.

[0025] Step 10: Repeat the method of step 9 to find a circle center O for each point on the outermost contour. These circle centers O will form a smaller red area again. Similarly to step 9, find the center point at each point on the outermost contour of the red area, and repeat the cycle until a unique circle center O is found. The circle center O is the point where the theoretical central axis of the engraved line at that location is located.

[0026] Step 11: The outermost pixel points on both sides of the groove are extracted again by the algorithm. The left endpoint P1 on one side of the groove is selected to calculate the straight line interval m between the point and all the points on the other side, that is, the interval of m pixels, and calculate the straight line distance l = m × k × h. The minimum value is found among all the straight line distances. The point is connected with P1 to obtain the midpoint Q1. The same step is applied to all the points on the side of the groove. All the midpoints Q are connected in sequence to form the actual central axis of the groove.

[0027] Step 12: According to the principle of step 11, calculate the minimum straight-line distance l between the center O of the red marked area and the actual central axis. min , if l min >0.5d, d is the tolerance bandwidth, then the current position of the scale line is considered unqualified and the excess value = l min -0.5d; if l min ≤0.5d, the scale line at the current position can be deemed qualified.

[0028] Preferably, the method further comprises:

[0029] Step 13: The PC-DMIS line measurement program automatically repeats steps 8 to 12 until all theoretical points extracted in advance are measured, and the computer outputs the measurement conclusion.

[0030] This application has the following technical effects:

[0031] 1. The automatic detection device designed by the present invention can replace the PH20 probe with a marking pen in situ and can automatically complete the marking. Compared with the previous manual application of red bile powder, the automatic detection device can ensure the uniformity of the size, color and roundness of the red mark, avoiding misjudgment caused by the appearance of the red mark; in addition, the device carries sufficient red ink and can automatically complete the marking work, which can significantly improve the detection efficiency of the flat marking of the tooling.

[0032] 2. Image recognition technology can be used to accurately and quickly detect tooling plane lines at the pixel level. Compared with the previous manual judgment of the relative position relationship between the red mark and the line, image recognition technology can quickly parse the center point of the red mark pixel cluster and the edge contour of the nearby line, and finally convert the distance between the center point of the red mark and the edge of the line into the actual size through the number of pixels. This method not only solves the problem of inaccurate measurement results caused by manual judgment, but also saves a lot of work time in processing structured light measurement point cloud data.

[0033] 3. The automatic detection device designed by the present invention can be quickly disassembled and assembled on the PH20 measuring base without complicated preparation work. It is only necessary to remove the PH20 measuring needle from the suction cup position and then install the automatic detection device in situ. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of a PH20 measuring head provided in an embodiment of the present application;

[0035] Figure 2 It is a schematic diagram of the structure of a tooling plane engraving automatic detection device provided in an embodiment of the present application;

[0036] Figure 3 is a perspective view of a fixed housing provided by an embodiment of the present application;

[0037] Figure 4 Schematic diagram of plane scribed line detection results;

[0038] Explanation of numbers in the figure: 1. PH20 measuring holder; 2. Automatic detection device; 11. Measuring rod; 12. Suction cup; 13. Measuring needle; 14. Ruby tip; 21. Wireless transmission module; 22. Industrial camera module; 23. Fixed housing; 24. Pen tip; 25. Marking pen; 26. Buffer spring; 27. Fixing screws (4 in total); 231. Industrial camera cabin; 232. Industrial camera lens cabin; 233. Screw fixing holes (4 in total); 234. Marking pen and buffer spring cabin; 235. Measuring rod fixing cabin; 236. Wireless transmission module cabin; 237. Measuring rod limit hole. DETAILED DESCRIPTION

[0039] The present invention provides an automatic detection device and method for tooling plane engraved lines based on image recognition. The automatic detection device containing a high-precision industrial camera and a marking pen is replaced with a measuring needle in situ on a PH20 measuring seat and fixed on a measuring rod, so that the marking pen and the measuring rod are kept coaxially aligned. The automatic detection device is controlled by a three-coordinate measuring machine to perform processes such as lowering the height to make marks and raising the height to take images one by one at theoretical positions extracted in advance. The images are transmitted to a computer through a wireless transmission module. A set algorithm can quickly parse the center point of a red-marked pixel group and the edge contour of nearby engraved lines. Finally, the distance between the center point of the red mark and the edge of the engraved line is converted into an actual size through the number of pixels. The above process can ensure that the automatic detection device can complete the detection task of the engraved lines while continuously operating until all theoretical positions extracted in advance are marked.

[0040] Among them, the PH20 measuring head includes a measuring rod, a suction cup, a measuring needle, and a ruby ​​tip. The PH20 measuring head is installed on the Z-axis transmission device of the three-dimensional coordinate measuring machine. The measuring rod is screwed and fixed to the bottom of the PH20 measuring head. The suction cup is divided into two parts, one part is fixed to the bottom of the measuring rod and the other part is fixed to the top of the measuring needle. The measuring needle can be quickly disassembled and assembled using the principle of magnets. The ruby ​​tip is fixed to the bottom of the measuring needle for touching the workpiece.

[0041] 1. The device designed by the present invention can replace the PH20 probe with a marker pen in situ and automatically complete the marking. The device is centrally installed on the PH20 probe rod. The position of the marker pen tip in the X and Y directions is consistent with that of the original PH20 probe. Only simple calibration is required to make the X and Y direction accuracy of the pen tip consistent with that of the three-dimensional coordinate measuring machine. A buffer spring is designed in the Z direction. When the pen tip touches the tooling surface, it will neither damage the pen tip nor the PH20 probe seat. When calibrating before use, set the safety plane of the three-dimensional coordinate measuring machine, and use the original engraved line measurement program to complete the automatic marking of the engraved line.

[0042] 2. Using image recognition technology, the plane engravings of tooling can be accurately and quickly detected at the pixel level. The characteristic of plane engravings is that the proportional relationship between pixels and actual size is only affected by the shooting distance, without the interference of curved surfaces and the distortion caused by illegal shooting, and the image size conversion technology is stable and mature. The above-mentioned stable technology can be used to quickly parse the center point of the red-marked pixel cluster and the edge contour of the nearby engraved lines. Finally, the distance between the center point of the red mark and the edge of the engraved line is converted into the actual size through the number of pixels, so that the plane engravings of tooling can be quickly and automatically detected. This method not only solves the problem of inaccurate measurement results caused by manual naked eye judgment, but also saves a lot of working time in processing structured light measurement point cloud data.

[0043] 3. The device designed by the present invention can be quickly disassembled and assembled on the PH20 measuring base without complicated preparation work. It only needs to remove the PH20 measuring needle from the suction cup position and install the device in situ; the tip of the marking pen replaces the ruby ​​end of the PH20 measuring needle. At the theoretical position of each engraved line extraction point, the measuring head descends along the Z item to a predetermined height value, and the pen tip touches the tooling surface to complete the marking. When the measuring head rises back to the predetermined height along the Z item, the industrial camera automatically captures the current position and transmits the image back to the computer by wireless transmission. The software automatically determines whether the point is qualified or not.

[0044] like Figure 1-Figure 4The tooling plane engraving automatic detection device based on image recognition is shown, comprising a PH20 measuring seat 1 and an automatic detection device 2. The PH20 measuring seat 1 comprises a measuring rod 11, a suction cup 12, a measuring needle 13, and a ruby ​​tip 14. The PH20 measuring seat 1 is installed on the Z-axis transmission device of the three-dimensional coordinate measuring machine. The measuring rod 11 is screwed and fixed at the bottom of the PH20 measuring seat 1. The suction cup 12 is divided into two parts, one part is fixed at the bottom of the measuring rod 11, and the other part is fixed at the top of the measuring needle 13. The measuring needle 13 is quickly disassembled and assembled by using the principle of magnets. The ruby ​​tip 14 is fixed at the bottom of the measuring needle 13 for touching the workpiece; the automatic detection device 2 comprises a wireless transmission module 21, an industrial phase The wireless transmission module 21 and the industrial camera module 22 are installed in the reserved space inside the fixed housing 23 in advance. The fixed housing 23 is fixed to the measuring rod 11 by the fixing screws 27 (the measuring needle 13 needs to be removed in advance). The pen tip 24 is installed in the bottom reserved hole of the marking pen 25. After the marking pen 25 is filled with red ink, it is axially aligned with the measuring rod 11 and installed in the reserved space at the bottom of the middle of the fixed housing 23 together with the buffer spring 26, and the marking pen 25 is fixed with the fixing screws 27. There are grooves on the side of the marking pen 25 to ensure After the screw 27 is tightened, the marking pen 25 will not fall out and the buffer spring 26 can be compressed along the Z direction; the fixed housing 23 includes an industrial camera cabin 231, an industrial camera lens cabin 232, screw fixing holes 233 (4 in total), a marking pen and buffer spring cabin 234, a measuring rod fixing cabin 235, a wireless transmission module cabin 236, and a measuring rod limiting hole 237. The industrial camera cabin 231 is designed according to the size of the industrial camera module 22 and the industrial camera module 22 is installed and packaged before use. At the same time, it is ensured that the lens of the industrial camera module 22 is vertically downward and within the industrial camera lens cabin 232. The two screw fixing holes 233 at the lower end are used to fix the marking pen 25. and buffer spring 26, the two screw fixing holes 233 at the upper end are used to fix the measuring rod 11 in the measuring rod fixing cabin 235, the marking pen and buffer spring cabin 234 can accommodate the marking pen 25 and the buffer spring 26 and ensure that they can move vertically up and down inside, the marking pen and buffer spring cabin 234 and the measuring rod fixing cabin 235 are not connected to ensure that the position of the automatic detection device 2 along the Z item is fixed, the wireless transmission module cabin 236 is designed according to the size of the wireless transmission module 21 and the wireless transmission module 21 is installed and packaged before use, and the measuring rod limiting hole 237 uses a hole with the same outer diameter as the measuring rod 11 to limit the X and Y direction degrees of freedom of the automatic detection device 2.

[0045] In other embodiments of the present application, a method for automatically detecting tooling plane markings based on image recognition comprises the following steps:

[0046] Step 1: Operate the coordinate measuring machine to return the PH20 measuring head 1 to the origin position of the coordinate measuring machine;

[0047] Step 2: Use the pre-set PC-DMIS program to let the ruby ​​tip 14 touch the standard ball with a pre-calibrated diameter to verify whether the accuracy of the three-dimensional coordinate measuring machine meets the expectations;

[0048] Step 3: Remove the measuring needle 13, pass the measuring rod 11 through the measuring rod limit hole 237 and the measuring rod fixing cabin 235 in sequence, and then tighten it with the screw 27 to ensure that the automatic detection device 2 will not loosen. At the same time, ensure that the measuring rod 11 reaches the bottom of the measuring rod fixing cabin 235 to ensure that the Z-direction height is fixed;

[0049] Step 4: Fill the marking pen 25 with red ink, put the buffer spring 26 and the fixed marking pen 25 into the marking pen and buffer spring compartment 234 in sequence, and tighten them with the screw 27 to ensure that the buffer spring 26 and the fixed marking pen 25 will not completely fall out;

[0050] Step 5: Turn on the wireless transmission module 21 and the industrial camera module 22 to confirm whether the connection with the computer is normal;

[0051] Step 6: Use the PC-DMIS program that has been set to implement to let the pen tip 24 test touch on the calibration plate with a scale, and use the industrial camera module 22 to capture the image and send it to the computer, confirm the scale base k (the size of each pixel at a unit distance) and the mark center falls on the center line of the calibration plate, which means that the automatic detection device 2 is considered to have normal accuracy and can be used;

[0052] Step 7: Use a height gauge to measure the height of the tooling to be tested on the measuring machine platform, and adjust the safety plane height h in the PC-DMIS program to ensure that the pen tip 24 will not be over-pressed to cause damage to the equipment;

[0053] Step 8 calls the PC-DMIS line measurement program pre-programmed for the tooling, and the three-dimensional coordinate measuring machine makes the pen tip 24 drop down to touch the tooling surface at each theoretical position extracted in advance, leaving a red mark, and then lifts it back to the safe plane height and starts the industrial camera module 22 to capture the image of the current part;

[0054] Step 9: The industrial camera module sends the image to the computer. The set algorithm first extracts the pixels of the red marked area, calculates all the points of the outermost contour of the red marked area, and randomly selects a point on the outermost contour, calculates the distance to other points on the outermost contour and finds the maximum value. The midpoint of the line connecting the maximum value position and the point is the center of the circle O.

[0055] Step 10: Repeat the method of step 9 to find a circle center O for each point on the outermost contour. These circle centers O will form a smaller red area again. Similarly to step 9, find the center point at each point on the outermost contour of the red area, and repeat the cycle until a unique circle center O is found. The circle center O is the point where the theoretical central axis of the engraved line at that location is located.

[0056] Step 11: The outermost pixel points on both sides of the groove are extracted again by the algorithm. The left endpoint P1 on one side of the groove is selected to calculate the straight line interval m (i.e., m pixels) between the point and all the points on the other side, and the straight line distance l = m × k × h is calculated. The minimum value is found among all the straight line distances. The point is connected with P1 to obtain the midpoint Q1. The same step is applied to all the points on the side of the groove. All the midpoints Q are connected in sequence to form the actual central axis of the groove.

[0057] Step 12: According to the principle of step 11, calculate the minimum straight-line distance l between the center O of the red marked area and the actual central axis. min , if l min >0.5d (d is the tolerance bandwidth), then the current position of the scale line is considered unqualified and the excess value = l min -0.5d; if l min ≤0.5d, the marking line at the current position can be deemed qualified;

[0058] Step 13: The PC-DMIS line measurement program automatically repeats steps 8 to 12 until all theoretical points extracted in advance are measured, and the computer outputs the measurement conclusion.

Claims

1. An automatic detection device for tooling plane marking lines based on image recognition, characterized in that: The device comprises a PH20 measuring seat and an automatic detection component; the PH20 measuring seat is installed on the Z-axis transmission device of the three-dimensional coordinate measuring machine, and the automatic detection component is connected to the PH20 measuring seat; Wherein, the automatic detection component includes a wireless transmission module, an industrial camera module, a fixed housing, a pen tip, a marking pen, a buffer spring, and a fixing screw; Among them, the wireless transmission module and the industrial camera module are pre-installed in the reserved space inside the fixed shell. The fixed shell is fixed to the measuring rod by fixing screws. The pen tip is installed in the reserved hole at the bottom of the marking pen. After the marking pen is filled with red ink, it is aligned with the measuring rod axially and installed in the reserved space at the bottom of the middle of the fixed shell together with the buffer spring, and the marking pen is fixed with fixing screws. There are grooves on the side of the marking pen to ensure that the marking pen will not fall out after the screws are tightened, and the buffer spring can also be compressed along the Z direction.

2. The device according to claim 1, characterized in that Before fixing the housing to the measuring rod with the fixing screws, the measuring needle must be removed in advance.

3. The device according to claim 1, characterized in that The fixed shell comprises an industrial camera cabin, an industrial camera lens cabin, screw fixing holes, a marking pen and buffer spring cabin, a measuring rod fixing cabin, a wireless transmission module cabin, and a measuring rod limiting hole.

4. The device according to claim 3, characterized in that The industrial camera cabin is designed according to the size of the industrial camera module and the industrial camera module is installed and packaged before use. At the same time, it is ensured that the lens of the industrial camera module is vertically downward and inside the industrial camera lens cabin. The two screw fixing holes at the lower end are used to fix the marking pen and the buffer spring, and the two screw fixing holes at the upper end are used to fix the fixed measuring rod in the measuring rod fixing cabin.

5. The device according to claim 4, characterized in that The marking pen and buffer spring can accommodate the marking pen and buffer spring and ensure that they can move vertically up and down inside. The marking pen and buffer spring compartment is not connected to the measuring rod fixing compartment to ensure that the position of the automatic detection device along the Z item is fixed.

6. The device according to claim 5, characterized in that The wireless transmission module cabin is designed according to the size of the wireless transmission module and the wireless transmission module is installed and packaged before use. The measuring rod limit hole uses a hole with the same outer diameter as the measuring rod to limit the X and Y direction freedom of the automatic detection device.

7. A method for automatically detecting tooling plane marking lines based on image recognition, characterized in that: The method comprises the following steps: Step 1: Operate the coordinate measuring machine to return the PH20 measuring head to the origin position of the coordinate measuring machine; Step 2: Use the pre-set PC-DMIS program to let the ruby ​​tip touch the standard ball with a pre-calibrated diameter to verify whether the accuracy of the coordinate measuring machine meets the expectations; Step 3: Remove the probe, pass the measuring rod through the measuring rod limit hole and the measuring rod fixing cabin in sequence, and tighten with screws to ensure that the automatic detection device will not loosen. At the same time, ensure that the measuring rod reaches the bottom of the measuring rod fixing cabin to ensure that the Z-direction height is fixed; Step 4: Fill the marker pen with red ink, put the buffer spring and fixed marker pen into the marker pen and buffer spring compartments in turn, and tighten them with screws to ensure that the buffer spring and fixed marker pen will not fall out completely; Step 5. Turn on the wireless transmission module and industrial camera module to confirm whether the connection with the computer is normal; Step 6. Use the pre-set PC-DMIS program to let the pen tip touch the calibration plate with a scale, take an image through the industrial camera module and send it to the computer, confirm that the scale base k is correct and the mark center falls on the center line of the calibration plate, which means that the automatic detection device is considered to have normal accuracy and can be used; the scale base k is the size of each pixel at a unit distance; Step 7. Use a height gauge to measure the height of the tooling to be tested on the measuring machine platform, and adjust the safety plane height h in the PC-DMIS program to ensure that the pen tip will not be over-pressed to cause damage to the equipment; Step 8: Call the pre-programmed PC-DMIS line measurement program for the tooling. The three-dimensional coordinate measuring machine will make the pen tip drop to touch the tooling surface at each pre-extracted theoretical position, leaving a red mark, and then lift it back to the safe plane height and start the industrial camera module to capture the image of the current part. Step 9. The industrial camera module sends the image to the computer. The set algorithm first extracts the pixels of the red marked area, calculates all the points of the outermost contour of the red marked area, and randomly selects a point on the outermost contour, calculates the distance to other points on the outermost contour and finds the maximum value. The midpoint of the line connecting the maximum value position and the point is the center of the circle O. Step 10, repeat the method of step 9, and find a circle center O for each point on the outermost contour. These circle centers O will form a smaller red area again; similarly to step 9, find the center point at each point on the outermost contour of the red area, and repeat the cycle until the only circle center O is found. The circle center O is the point where the theoretical central axis of the engraved line at that location is located; Step 11, extract the outermost pixel points on both sides of the groove of the scribed line again through the algorithm, select the left end point P1 on one side of the groove of the scribed line, and calculate the straight line interval m between this point and all points on the other side, that is, the interval of m pixels, and calculate the straight line distance l = m × k × h, find the minimum value among all the straight line distances, connect this position point with P1, and get the midpoint Q1; apply this step to all points on this side of the groove in the same way, and connect all the midpoints Q in sequence to form the actual central axis of the scribed line; Step 12: According to the principle of step 11, calculate the minimum straight-line distance l between the center O of the red marked area and the actual central axis min , if l min >0.5d, d is the tolerance bandwidth, then it can be determined that the scale line at the current position is unqualified and the excess value = l min -0.5d; if l min ≤0.5d, the scale line at the current position can be deemed qualified.

8. The method according to claim 7, characterized in that The method further comprises: Step 13: The PC-DMIS line measurement program automatically repeats steps 8 to 12 until all theoretical points extracted in advance are measured, and the computer outputs the measurement conclusion.

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