Honeycomb work positioning and punching method

Abstract

This invention relates to the field of workpiece processing technology, and in particular to a method for positioning and drilling honeycomb workpieces. The steps are as follows: S1, screening and arranging of group holes; S2, selection of reference points; S3, determination of reference points; S4, correction of reference points; S5, formation of drilling trajectory. This invention provides a method for positioning and drilling honeycomb workpieces that can accurately identify and locate the position of reference holes, with high drilling accuracy and high drilling efficiency.

Description

Technical Field

[0001] This invention relates to the field of honeycomb workpiece processing technology, and in particular to a method for positioning and drilling honeycomb workpieces. Background Technology

[0002] A gasoline particulate filter (GPF) is a ceramic filter installed in the emission system of a gasoline engine. The GPF uses a wall-flow honeycomb ceramic carrier, which contains numerous parallel axial honeycomb channels. In each adjacent channel, one channel has only an inlet, and the other only an outlet. Exhaust gas flows in through the open inlet channel, passes through the porous wall of the GPF carrier, and exits through the adjacent channel. The wall-flow honeycomb ceramic carrier is formed by regularly plugging holes in a honeycomb-shaped ceramic workpiece, creating a single-opening structure for adjacent holes. The honeycomb workpiece is manufactured with fully open holes, requiring plugging according to a specific pattern. Before plugging, adhesive tape is applied to the workpiece, and then holes are punched in the tape at the locations requiring plugging according to a set pattern.

[0003] Currently, the commonly used drilling method involves using a camera to image the workpiece, identifying the holes, and then sorting the identified holes in the camera coordinate system from top to bottom and from left to right (i.e., x-coordinate values ​​increase from left to right, and y-coordinate values ​​increase from top to bottom). The hole in the upper left corner is then selected as the reference hole, i.e., the hole with the smallest x and y coordinate values. Finally, drilling is performed according to the drilling pattern and the spacing between holes. However, since honeycomb-shaped workpieces are mostly die-cast parts, the holes on the periphery are often deformed due to slight curvature at the workpiece edges. This leads to inaccurate selection of the reference hole using the above method, resulting in off-center holes and low drilling accuracy. Furthermore, interference from ambient light or debris, or defects or missing holes in the upper left corner of the workpiece, can cause the upper left corner hole to be unidentified, making it impossible or incorrect to select the reference hole position. This requires human intervention, affecting drilling efficiency and accuracy. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for positioning and drilling honeycomb workpieces with high drilling accuracy and high drilling efficiency, which can accurately identify and locate the position of the reference hole.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for positioning and drilling honeycomb-shaped workpieces, the steps of which are as follows:

[0006] S1. Screening and arrangement of holes: The camera takes pictures of the workpiece, screens out the holes on the workpiece, and arranges the screened holes in order from top to bottom and from left to right.

[0007] S2. Selection of reference points: Based on the camera coordinate system, calculate the center coordinates of the first row of holes and the first column of holes, perform linear fitting on the center coordinates of the first row of holes to form a row line, perform linear fitting on the center coordinates of the first column of holes on the workpiece to form a column line, and use the intersection of the row line and the column line as the reference point.

[0008] S3. Determination of reference point: If the difference between the coordinates of the reference point and the average coordinates of the center of the first row of holes is less than half the length of the hole, and the difference between the coordinates of the reference point and the average coordinates of the center of the first column of holes is less than half the length of the hole, then proceed to step S5; otherwise, proceed to step S4.

[0009] S4. Correction of reference points: Remove X-axis coordinate data in the first row of holes whose difference from the average X-axis coordinate of the center of the first row of holes is greater than half the length of the hole. At the same time, remove Y-axis coordinate data in the first column of holes whose difference from the average Y-axis coordinate of the center of the first column of holes is greater than half the length of the hole. Then, use the average X-axis coordinate of the center of the first row of holes and the average Y-axis coordinate of the center of the first column of holes as the reference point coordinates.

[0010] S5. Formation of the drilling trajectory: First, the reference point coordinates are used as the starting point. The position of the drilling position is determined according to the drilling pattern and the spacing between holes. Then, the edge detection algorithm is used to outline the drilling contour and generate the drilling trajectory.

[0011] Furthermore, the specific steps of step S5 are as follows:

[0012] S51. Determining the location of the drilling position: Taking the reference point coordinates as the starting point, calculate the center coordinates of the drilling position according to the drilling pattern and the spacing between holes;

[0013] S52. Outline of the punching position: Using the center coordinates of the punching position as the center, select the image at the punching position with a square area 2 pixels larger than the hole size, select the local ROI area, and filter the edge points of the punching position based on the edge detection algorithm to form the punching outline.

[0014] S53. Correction of the center coordinates of the punching position: Replace the center coordinates of the punching position in step S51 with the centroid coordinates of the punching profile of the current punching position, and calculate the center coordinates of the next punching position starting from the corrected center coordinates.

[0015] S53. Transformation of the punching profile: Using the center of the punching position as the local center, subtract the corrected center coordinates from the coordinates of the edge points, multiply by the scaling factor, and then add the corrected center coordinates to generate the punching trajectory.

[0016] Furthermore, the hole screening step in step S1 is as follows:

[0017] The image captured by the camera is processed in grayscale, and grayscale histogram statistics are performed. Based on the grayscale histogram, a certain grayscale value is selected as the grayscale threshold to perform binarization processing on the image. Then, the holes on the workpiece are screened based on the area size of the holes.

[0018] Furthermore, it also includes the logic for determining missed calls, as detailed below:

[0019] During the generation of the drilling trajectories for the first row of holes, the first column of holes, the last row of holes, and the last column of holes, if there are N consecutive positions where the drilling outline is missing, it is considered that the overall generated drilling outline is skewed.

[0020]

[0021] Where N is the number of non-drilled profiles, M is the number of holes per row or column, and r is the set ratio.

[0022] Furthermore, it also includes corrective measures for missed printing, as detailed below:

[0023] When a missed print is detected, if the missed print is detected in the first row, the X coordinate of the reference point in the camera coordinate system is increased by one hole size; if the missed print is detected in the first column, the Y coordinate of the reference point in the camera coordinate system is increased by one hole size; if the missed print is detected in the last row, the X coordinate of the reference point in the camera coordinate system is decreased by one hole size; if the missed print is detected in the last column, the Y coordinate of the reference point in the camera coordinate system is decreased by one hole size.

[0024] Furthermore, in step S2, the line fitting uses the least squares method, and the formula is as follows:

[0025]

[0026]

[0027] in, This represents the average X-axis coordinate of the center of the first row or first column of holes. This represents the average value of the Y-axis coordinate of the center of the first row or column of holes.

[0028] Furthermore, the steps of the edge detection algorithm in step S52 are as follows:

[0029] S521. Blur Processing: Noise reduction is performed on the acquired image based on a Gaussian filtering algorithm. The Gaussian filtering formula is:

[0030]

[0031] in, Represents pixels grayscale value at that location This represents the grayscale value after processing by the Gaussian filtering algorithm. Indicates standard deviation;

[0032] S522. Calculation of gradient strength and gradient direction: The gradient values ​​in the x and y directions are obtained based on the Sobel operator. and Then, the gradient strength and gradient direction are calculated using the following formula:

[0033]

[0034]

[0035] in, Indicates gradient strength. Indicates the gradient direction;

[0036] S523, Edge Refinement: Based on non-maximum suppression, the edges in the gradient map are refined to a one-pixel width;

[0037] S524, Edge Filtering: Based on dual thresholds, candidate pixels are filtered;

[0038] S525, Edge Detection: First, determine whether a point exceeds a high threshold. Points exceeding the high threshold are edge points. Then, find edge points exceeding the low threshold in the 8 neighboring points of that point. Collect new edges from this point until the entire image edge is closed.

[0039] Furthermore, the Sobel operator formula is as follows:

[0040]

[0041] .

[0042] The beneficial effects of this invention are:

[0043] (1) The present invention arranges the selected holes in order from top to bottom and from left to right, and then performs linear fitting on the center coordinates of the first row of holes and the first column of holes to form row lines and column lines. The intersection of the row lines and column lines is calculated to obtain the reference point (i.e. the center coordinates of the reference hole), thereby realizing the accurate identification and positioning of the reference hole position, avoiding the influence of workpiece edge deformation, and allowing some holes in the first row or first column to be unidentified. Then, with the reference point as the starting point, the center coordinates of the subsequent drilling positions are calculated according to the spacing between holes and the drilling rules, and the edge of the hole in the subsequent drilling position is accurately generated by the edge detection algorithm to form the drilling trajectory, thereby improving the drilling efficiency and drilling accuracy.

[0044] (2) The present invention uses an edge detection algorithm to filter the edge points of the punching position to form the punching outline. Then, the center coordinates of the punching position are corrected by the centroid coordinates of the punching outline, and the center coordinates of the next punching position are calculated from the corrected center coordinates. This ensures the accurate positioning of each punching position and the accurate formation of the punching outline, and further improves the punching accuracy.

[0045] (3) The present invention performs binarization processing on the image and then filters the holes on the workpiece based on the area size of the holes, so as to ensure that as many holes on the workpiece as possible can be filtered out, thus ensuring the positioning accuracy of the reference point.

[0046] (4) The present invention improves practicality and ensures yield by setting up the missing print judgment logic and the missing print correction measures. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to preferred embodiments.

[0048] Example 1

[0049] A method for positioning and drilling honeycomb-shaped workpieces, comprising the following steps:

[0050] S1. Screening and arrangement of holes: The camera takes pictures of the workpiece, screens out the holes on the workpiece, and arranges the screened holes in order from top to bottom and from left to right.

[0051] The steps for group pore screening are as follows:

[0052] The image captured by the camera is processed in grayscale, and grayscale histogram statistics are performed. Based on the grayscale histogram, a certain grayscale value is selected as the grayscale threshold to perform binarization processing on the image. Then, the holes on the workpiece are screened based on the area size of the holes.

[0053] By binarizing the image and then filtering the holes on the workpiece based on their area size, as many holes as possible can be filtered out to ensure the positioning accuracy of the reference point.

[0054] S2. Selection of reference points: Based on the camera coordinate system, calculate the center coordinates of the first row of holes and the first column of holes. Perform linear fitting on the center coordinates of the first row of holes to form a row line, and perform linear fitting on the center coordinates of the first column of holes to form a column line. Use the intersection of the row line and the column line as the reference point.

[0055] S3. Determination of reference point: If the difference between the reference point coordinates and the average value of the center coordinates of the first row of holes is less than half the hole length, and the difference between the reference point coordinates and the average value of the center coordinates of the first column of holes is less than half the hole length, then proceed to step S5; otherwise, proceed to step S4.

[0056] S4. Calibration of reference points: Remove X-axis coordinate data in the first row of holes whose difference from the average X-axis coordinate of the center of the first row of holes is greater than half the hole length. At the same time, remove Y-axis coordinate data in the first column of holes whose difference from the average Y-axis coordinate of the center of the first column of holes is greater than half the hole length. Then, use the average X-axis coordinate of the center of the first row of holes and the average Y-axis coordinate of the center of the first column of holes as the reference point coordinates.

[0057] By determining and correcting the reference points, the rationality and accuracy of the reference point selection are ensured, thereby guaranteeing the accurate determination of the subsequent drilling positions.

[0058] S5. Formation of the drilling trajectory: Starting from the reference point coordinates, the position of the drilling position is determined according to the drilling pattern and the spacing between holes. Then, the edge detection algorithm is used to outline the drilling contour and generate the drilling trajectory.

[0059] This application arranges the selected holes in order from top to bottom and from left to right. Then, it performs linear fitting on the center coordinates of the holes in the first row and the first column to form row lines and column lines. The intersection of the row lines and column lines is calculated to obtain the reference point (i.e., the center coordinates of the reference hole). This achieves accurate identification and positioning of the reference hole position, avoids the influence of workpiece edge deformation, and allows some holes in the first row or first column to be unidentified. Then, using the reference point as the starting point, the center coordinates of the subsequent drilling positions are calculated according to the spacing between holes and the drilling pattern. The edge of the subsequent drilling positions is accurately generated through the edge detection algorithm to form the drilling trajectory, thereby improving drilling efficiency and drilling accuracy.

[0060] The specific steps of step S5 are as follows:

[0061] S51. Determining the location of the drilling position: Taking the reference point coordinates as the starting point, calculate the center coordinates of the drilling position according to the drilling pattern and the spacing between holes.

[0062] S52. Outline of the punching location: Using the center coordinates of the punching location as the center, select the image at the punching location with a square area 2 pixels larger than the hole size, select the local ROI area, and filter the edge points of the punching location based on the edge detection algorithm to form the punching outline.

[0063] By using the center coordinates of the punching position as the center and selecting a square area 2 pixels larger than the hole size in the image at the punching position, the influence of errors in the center coordinate calculation process is avoided, ensuring that the punching position can be completely selected.

[0064] S53. Correction of the center coordinates of the punching position: Replace the center coordinates of the punching position in step S51 with the centroid coordinates of the punching profile of the current punching position, and calculate the center coordinates of the next punching position starting from the corrected center coordinates.

[0065] S53. Transformation of the punching profile: Using the center of the punching position as the local center, subtract the corrected center coordinates from the coordinates of the edge points, multiply by the scaling factor, and then add the corrected center coordinates to generate the punching trajectory.

[0066] Edge detection algorithms are used to filter edge points of the punching positions to form punching contours. Then, the centroid coordinates of the punching contours are used to correct the center coordinates of the punching positions. The center coordinates of the next punching position are calculated using the corrected center coordinates as the starting point. This ensures the accurate positioning of each punching position and the precise formation of the punching contours, further improving punching accuracy.

[0067] In step S2, the least squares method is used for linear fitting, and the formula is as follows:

[0068]

[0069]

[0070] in, This represents the average X-axis coordinate of the center of the first row or first column of holes. This represents the average value of the Y-axis coordinate of the center of the first row or column of holes.

[0071] The least squares method was used for linear fitting, which reduced the fitting error and further improved the positioning accuracy of the reference point, thus highly restoring the position of the hole in the upper left corner of the workpiece.

[0072] The steps of the edge detection algorithm in step S52 are as follows:

[0073] S521. Blur Processing: Noise reduction is performed on the acquired image based on a Gaussian filtering algorithm. The Gaussian filtering formula is:

[0074]

[0075] in, Represents pixels grayscale value at that location This represents the grayscale value after processing by the Gaussian filtering algorithm. Indicates standard deviation;

[0076] S522. Calculation of gradient strength and gradient direction: The gradient values ​​in the x and y directions are obtained based on the Sobel operator. and Then, the gradient strength and gradient direction are calculated using the following formula:

[0077]

[0078]

[0079] in, Indicates gradient strength. Indicates the gradient direction;

[0080] S523, Edge Refinement: Based on non-maximum suppression, the edges in the gradient map are refined to a one-pixel width;

[0081] S524, Edge Filtering: Based on dual thresholds, candidate pixels are filtered;

[0082] S525, Edge Detection: First, determine whether a point exceeds a high threshold. Points exceeding the high threshold are edge points. Then, find edge points exceeding the low threshold in the 8 neighboring points of that point. Collect new edges from this point until the entire image edge is closed.

[0083] The Sobel operator formula is:

[0084]

[0085] .

[0086] Example 2

[0087] Although the missing punch rate of the punching method in Example 1 is less than one in a thousand, in order to improve practicality and ensure the yield rate, this example also sets up missing punch judgment logic and missing punch correction measures.

[0088] The specific logic for determining missed calls is as follows:

[0089] During the generation of the drilling trajectories for the first row of holes, the first column of holes, the last row of holes, and the last column of holes, if there are N consecutive positions where the drilling outline is missing, it is considered that the overall generated drilling outline is skewed.

[0090]

[0091] Where N is the number of non-drilled profiles, M is the number of holes per row or column, and r is the set ratio.

[0092] It should be noted that the smaller the value of r, the stricter the judgment of missed calls. In this embodiment, r is 0.5.

[0093] The specific corrective measures for missed printing are as follows:

[0094] When a missed print is detected, if the missed print is detected in the first row, the X coordinate of the reference point in the camera coordinate system is increased by one hole size; if the missed print is detected in the first column, the Y coordinate of the reference point in the camera coordinate system is increased by one hole size; if the missed print is detected in the last row, the X coordinate of the reference point in the camera coordinate system is decreased by one hole size; if the missed print is detected in the last column, the Y coordinate of the reference point in the camera coordinate system is decreased by one hole size.

[0095] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for positioning and drilling honeycomb-shaped workpieces, characterized in that, The steps are as follows: S1. Screening and arrangement of holes: The camera takes pictures of the workpiece, screens out the holes on the workpiece, and arranges the screened holes in order from top to bottom and from left to right. S2. Selection of reference points: Based on the camera coordinate system, calculate the center coordinates of the first row of holes and the first column of holes, perform linear fitting on the center coordinates of the first row of holes to form a row line, perform linear fitting on the center coordinates of the first column of holes on the workpiece to form a column line, and use the intersection of the row line and the column line as the reference point. S3. Determination of reference point: If the difference between the coordinates of the reference point and the average coordinates of the center of the first row of holes is less than half the length of the hole, and the difference between the coordinates of the reference point and the average coordinates of the center of the first column of holes is less than half the length of the hole, then proceed to step S5; otherwise, proceed to step S4. S4. Correction of reference points: Remove X-axis coordinate data in the first row of holes whose difference from the average X-axis coordinate of the center of the first row of holes is greater than half the length of the hole. At the same time, remove Y-axis coordinate data in the first column of holes whose difference from the average Y-axis coordinate of the center of the first column of holes is greater than half the length of the hole. Then, use the average X-axis coordinate of the center of the first row of holes and the average Y-axis coordinate of the center of the first column of holes as the reference point coordinates. S5. Formation of the drilling trajectory: First, the reference point coordinates are used as the starting point. The position of the drilling position is determined according to the drilling pattern and the spacing between holes. Then, the edge detection algorithm is used to outline the drilling contour and generate the drilling trajectory.

2. The method for positioning and drilling honeycomb-shaped workpieces according to claim 1, characterized in that, The specific steps of step S5 are as follows: S51. Determining the location of the drilling position: Taking the reference point coordinates as the starting point, calculate the center coordinates of the drilling position according to the drilling pattern and the spacing between holes; S52. Outline of the punching position: Using the center coordinates of the punching position as the center, select the image at the punching position with a square area 2 pixels larger than the hole size, select the local ROI area, and filter the edge points of the punching position based on the edge detection algorithm to form the punching outline. S53. Correction of the center coordinates of the punching position: Replace the center coordinates of the punching position in step S51 with the centroid coordinates of the punching profile of the current punching position, and calculate the center coordinates of the next punching position starting from the corrected center coordinates. S53. Transformation of the punching profile: Using the center of the punching position as the local center, subtract the corrected center coordinates from the coordinates of the edge points, multiply by the scaling factor, and then add the corrected center coordinates to generate the punching trajectory.

3. The method for positioning and drilling honeycomb-shaped workpieces according to claim 1, characterized in that, The hole screening steps in step S1 are as follows: The image captured by the camera is processed in grayscale, and grayscale histogram statistics are performed. Based on the grayscale histogram, a certain grayscale value is selected as the grayscale threshold to perform binarization processing on the image. Then, the holes on the workpiece are screened based on the area size of the holes.

4. The method for positioning and drilling honeycomb-shaped workpieces according to claim 1, characterized in that, It also includes the logic for determining missed calls, as detailed below: During the generation of the drilling trajectories for the first row of holes, the first column of holes, the last row of holes, and the last column of holes, if there are N consecutive positions where the drilling outline is missing, it is considered that the overall generated drilling outline is skewed. N = r * M Where N is the number of non-drilled profiles, M is the number of holes per row or column, and r is the set ratio.

5. The method for positioning and drilling honeycomb-shaped workpieces according to claim 4, characterized in that, It also includes corrective measures for missed printing, as detailed below: When a missed print is detected, if the missed print is detected in the first row, the X coordinate of the reference point in the camera coordinate system is increased by one hole size; if the missed print is detected in the first column, the Y coordinate of the reference point in the camera coordinate system is increased by one hole size; if the missed print is detected in the last row, the X coordinate of the reference point in the camera coordinate system is decreased by one hole size; if the missed print is detected in the last column, the Y coordinate of the reference point in the camera coordinate system is decreased by one hole size.

6. The method for positioning and drilling honeycomb-shaped workpieces according to claim 1, characterized in that, In step S2, the line fitting uses the least squares method, and the formula is: y = kx + b in, This represents the average X-axis coordinate of the center of the first row or first column of holes. This represents the average value of the Y-axis coordinate of the center of the first row or column of holes.

7. The method for positioning and drilling honeycomb-shaped workpieces according to claim 2, characterized in that, The steps of the edge detection algorithm in step S52 are as follows: S521. Blur Processing: Noise reduction is performed on the acquired image based on a Gaussian filtering algorithm. The Gaussian filtering formula is: Where f(m,n) represents the gray value at pixel (m,n), g σ (m,n) represents the gray value after processing by the Gaussian filtering algorithm, and σ represents the standard deviation; S522. Calculation of gradient strength and gradient direction: Based on the Sobel operator, the gradient values ​​g in the x and y directions are obtained respectively. x (m,n) and g y (m,n), then calculate the gradient strength and gradient direction, using the formula: Where G(m,n) represents the gradient intensity and θ represents the gradient direction; S523, Edge Refinement: Based on non-maximum suppression, the edges in the gradient map are refined to a one-pixel width; S524, Edge Filtering: Based on dual thresholds, candidate pixels are filtered; S525, Edge Detection: First, determine whether a point exceeds a high threshold. Points exceeding the high threshold are edge points. Then, find edge points exceeding the low threshold in the 8 neighboring points of that point. Collect new edges from this point until the entire image edge is closed.

8. The method for positioning and drilling honeycomb-shaped workpieces according to claim 7, characterized in that, The Sobel operator formula is:

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