A method for establishing a workpiece coordinate system origin for single grain grinding with a variable workpiece pose grinding jig

Abstract

The present application belongs to the field of mechanical processing, and particularly relates to a grinding clamp for single-grit grinding and a method for establishing a workpiece coordinate system zero point, which can also be used for multi-grit grinding and coordinate system zero point establishment. The clamp specifically comprises a micro-feeding displacement table fixing component and a workpiece positioning component. Before use, the micro-feeding displacement table is fixed on a test table, and the workpiece positioning component is fixed on the displacement table. After the workpiece is fixed on the corresponding positioning component, the position changing device is adjusted to make the workpiece perpendicular to the feeding direction of the micro-feeding displacement table. During grinding, a CCD camera is used to collect images of the workpiece grinding surface, and the data is transmitted to a self-developed program for comparison and data analysis. The present application is mainly used in micro-grinding for material removal mechanism research, and realizes accurate control of the grinding depth.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of mechanical processing, and particularly relates to a grinding fixture for single abrasive grain grinding and a method for establishing zero point of workpiece coordinate system. BACKGROUND

[0002] In the single abrasive grain grinding experiment, image collection and defect morphology analysis of the defects on the machined workpiece surface are often needed to obtain corresponding data better, and therefore high accuracy is required in the image information collection; however, the defect size generated during grinding is extremely small, the grinding depth is difficult to control accurately, and the grinding zero point and the defect morphology after grinding cannot be directly observed by people, so more accurate data cannot be obtained; meanwhile, the workpiece to be machined needs to be positioned and adjusted with higher accuracy during grinding to control the single abrasive grain cutting depth and avoid unnecessary interference between the workpiece and the B fixture body, so the existing ordinary fixture and detection method cannot be used for positioning, clamping and detecting the workpiece.

[0003] In view of the above problems, the present application provides a grinding fixture for single abrasive grain grinding and a method for establishing zero point of workpiece coordinate system. SUMMARY

[0004] The present application aims to provide a grinding fixture for single abrasive grain grinding and a method for establishing zero point of workpiece coordinate system.

[0005] The grinding fixture for single abrasive grain grinding and the method for establishing zero point of workpiece coordinate system are characterized in that the fixture for single abrasive grain grinding comprises a workpiece to be machined, a pressing plate, a rectangular support block, a large L-shaped pad, a medium L-shaped arc pad, a small L-shaped pad, a micro-adjusting screw, a micro-adjusting nut, a screw M6 and a screw M8.

[0006] The grinding fixture for single abrasive grain grinding and the method for establishing zero point of workpiece coordinate system are implemented according to the following steps:

[0007] I. Installation of the fixture and fixation of the workpiece: the pressing plate is fixed on the surface of the test table by the screw M8; the rectangular support block is fixed on the corresponding position of the pressing plate by the screw M6; the bottom surface of the micro-feeding displacement table is fixed on the rectangular support block by the screw M6; the large L-shaped pad is fixed on the micro-feeding displacement table by the screw M6; the medium L-shaped arc pad is connected with the large L-shaped pad by the micro-adjusting screw, and the micro-adjusting nut is installed; the workpiece to be machined is adhered to the two inner end surfaces of the small L-shaped pad by using paraffin, and after the paraffin cools and solidifies, the small L-shaped pad is fixed on the medium L-shaped arc pad by the screw M6, thereby completing the installation of the fixture and the fixation of the workpiece.

[0008] II. Adjust the position of the workpiece to be processed relative to the micro-feeding displacement table feeding direction: rotate the micro-adjustment nut, coarsely adjust the angle of the workpiece to be processed relative to the micro-feeding displacement table feeding direction, so that it is approximately perpendicular to the feeding direction; measure the angle error using a dial gauge, and rotate the micro-adjustment nut again to make it perpendicular to the feeding direction, ensuring the cutting depth of the workpiece to be processed and preventing interference between the fixture and the tool.

[0009] III. Grinding method and workpiece coordinate system zero point establishment method: first, control the feeding amount and feeding rate of the micro-feeding displacement table to make the fixture and the workpiece to be processed approach the tool with a single abrasive grain along the feeding direction; connect the small CCD camera connection port to the computer server terminal, and connect the camera port close to the tool and the workpiece to be processed, adjust the camera position to clearly capture the ground surface of the workpiece and collect and transmit image information in real time; control the feeding amount of the micro-feeding displacement table to be 1 μm, adjust the feeding rate, continue to move the fixture and the workpiece to be processed along the feeding direction, detect and judge whether the tool and the workpiece surface have been ground through image acquisition, and the specific image detection and workpiece coordinate system zero point establishment method is as follows:

[0010] ① Image preprocessing: import the image collected by the CCD camera into matlab, remove the discrete noise signals in the image by wavelet threshold denoising method; use imhist operator to obtain the gray histogram of the image, modify the gray value to enhance the image, and improve the image recognition degree; cut off and enlarge the theoretical estimated range of the grinding area in the image to avoid the influence of insufficient light on the edge;

[0011] ② Image binarization: use Canny operator to perform image binarization on the preprocessed image, so that the grinding area appears white and the non-grinding area appears black;

[0012] ③ Calculate the area of the grinding area: calculate the area of the white area in the binarized image; when the area is greater than zero, the workpiece surface is ground, and the workpiece surface grinding zero point coordinate system is established;

[0013] The grinding fixture and the workpiece surface grinding zero point coordinate system establishment method for single abrasive grain grinding can also be used for multi-abrasive grain grinding and workpiece surface grinding zero point coordinate system establishment.

[0014] Compared with the existing single abrasive particle grinding clamp and zero point coordinate system establishment method, the beneficial effects of the present application are: (1) the clamp can position and adjust the workpiece to be processed with higher precision to control the depth of cut of the single abrasive particle and avoid unnecessary interference between the workpiece and the tool body; (2) the zero point coordinate system establishment method can collect images of the defects on the surface of the processed workpiece with higher precision and calculate the actual defect size, so that more accurate data can be obtained; (3) in the micro-grinding of material removal mechanism research, the grinding depth can be accurately controlled. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the overall schematic diagram of the single abrasive particle grinding clamp (without cooperating with the grinding tool)

[0016] Figure 2 is the overall schematic diagram of the single abrasive particle grinding clamp (cooperating with the grinding tool)

[0017] Figure 3 is the front view of the single abrasive particle grinding clamp (without cooperating with the grinding tool)

[0018] Figure 4 is the top view of the single abrasive particle grinding clamp (without cooperating with the grinding tool)

[0019] Figure 5 is the side view of the single abrasive particle grinding clamp (without cooperating with the grinding tool)

[0020] Figure 6 is the overall schematic diagram of the medium L-shaped arc pad

[0021] In the figure: 1, workpiece to be processed; 2, pressing plate; 3, rectangular support block; 4, large L-shaped pad; 5, medium L-shaped arc pad; 6, small L-shaped pad; 7, micro-adjustment screw; 8, micro-adjustment nut; 9, screw M6; 10, screw M8; 101, grinding tool; 102, micro-feeding displacement table. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the present application.

[0023] Specific embodiment one: a single abrasive particle grinding clamp and zero point coordinate system establishment method, characterized by comprising a workpiece to be processed, a pressing plate, a rectangular support block, a large L-shaped pad, a medium L-shaped arc pad, a small L-shaped pad, a micro-adjustment screw, a micro-adjustment nut, a screw M6, and a screw M8.

[0024] The micro-feeding displacement table fixing component in the embodiment includes a pressing plate and a rectangular support block. The upper and lower end faces of the fixed end of the rectangular support block are processed by using the slow wire-cut electrical discharge machining technology, and the processed component is drilled.

[0025] The workpiece positioning component in the embodiment includes a large L-shaped pad, a medium L-shaped arc pad, a small L-shaped pad, a micro-adjusting screw and a micro-adjusting nut. When the large L-shaped pad and the small L-shaped pad are processed, the outer end faces of the two pads are ground by using the grinding method, and one of the end faces is used as a positioning face. The two faces of the large L-shaped pad and the small L-shaped pad are processed by using the slow wire-cut electrical discharge machining technology. Then, the inner end faces of the two pads are processed by using the same method. After the processing is completed, the pads are drilled, reamed and counterbored to ensure the position accuracy and size accuracy of the holes. When the medium L-shaped arc pad is processed, the inner end faces of the pad are ground by using the grinding method, and one of the end faces is used as a positioning face. The two faces of the medium L-shaped arc pad are processed by using the slow wire-cut electrical discharge machining technology. Then, the outer end faces of the pad are processed by using the same method. The two arc faces of the outer end faces are symmetric about the central axis of the face. After the processing is completed, the pad is drilled, reamed and counterbored to ensure the position accuracy and size accuracy of the holes.

[0026] Specific embodiment two: the single abrasive particle grinding clamp and the zero coordinate system establishment method are specifically implemented according to the following steps.

[0027] I. Installation of the clamp and fixation of the workpiece: the pressing plate is fixed on the surface of the test table by using the screw M8; the rectangular support block is fixed on the corresponding position of the pressing plate by using the screw M6; the bottom surface of the micro-feeding displacement table is fixed on the rectangular support block by using the screw M6; the large L-shaped pad is fixed on the micro-feeding displacement table by using the screw M6; the medium L-shaped arc pad is connected with the large L-shaped pad by using the micro-adjusting screw, and the micro-adjusting nut is installed; the workpiece to be processed is adhered to the two inner end faces of the small L-shaped pad by using the paraffin, and the small L-shaped pad is fixed on the medium L-shaped arc pad by using the screw M6 after the paraffin is cooled and solidified, so that the installation of the clamp and the fixation of the workpiece are completed.

[0028] II. Adjustment of the position of the workpiece to be processed relative to the feeding direction of the micro-feeding displacement table: the micro-adjusting nut is rotated to coarsely adjust the angle of the workpiece to be processed relative to the feeding direction of the micro-feeding displacement table, so that the workpiece is approximately perpendicular to the feeding direction; the angle error is measured by using the dial gauge, the micro-adjusting nut is rotated again, so that the workpiece is perpendicular to the feeding direction, and the cutting depth of the workpiece to be processed is ensured to prevent the interference between the clamp and the tool.

[0029] Three, grinding method and workpiece coordinate system zero point establishment method: first control the feed amount and feed rate of micro-feeding displacement table, make the clamp and the workpiece to be processed close to the tool provided with a single abrasive grain along the feed direction; connect the small CCD camera connection port to the computer server terminal, and connect the camera port close to the tool and the workpiece to be processed, adjust the position of the camera, so that it can clearly shoot the workpiece surface to be ground and collect and transmit image information in real time; control the feed amount of micro-feeding displacement table is 1 μm, adjust the feed rate, continue to move the clamp and the workpiece to be processed along the feed direction, detect and judge whether the tool and the workpiece surface to be processed are ground through image acquisition, the specific image detection and workpiece coordinate system zero point establishment method is as follows:

[0030] ①Image preprocessing: import the image collected by the CCD camera into matlab, remove the discrete noise signal in the image by wavelet threshold denoising method; adopt imhist operator to obtain the gray histogram of the image, modify the gray value to enhance the image, and improve the image recognition degree; the theoretical estimated range of the grinding area in the image is intercepted and enlarged to avoid the influence of insufficient light on the edge;

[0031] ②Image binarization: adopt Canny operator to perform image binarization on the preprocessed image, so that the grinding area presents white color and the non-grinding area presents black color;

[0032] ③Calculate the area of the grinding area: calculate the area of the white area in the binarized image; when the area is greater than zero, the workpiece surface is ground, and the workpiece surface grinding zero point coordinate system is established;

[0033] Specific embodiment three: a grinding clamp and workpiece coordinate system zero point establishment method for single abrasive grain grinding with variable workpiece pose, the grinding and zero point coordinate system establishment method can also be used for grinding and workpiece surface grinding zero point coordinate system establishment of multiple abrasive grains, the implementation steps are the same as the above embodiment.

Claims

1. A method for establishing the origin of the workpiece coordinate system based on the transformable fixture for single abrasive particle grinding, characterized in that, Single abrasive grain grinding fixture including variable pose clamp, the fixture includes workpiece (1) to be processed, trace feed displacement table fixed component, workpiece positioning component and connecting component; The trace feed displacement table fixed component includes: a pressing plate (2), a rectangular support block (3); The workpiece positioning component includes: a large L-shaped pad block (4), a medium L-shaped arc pad block (5), a small L-shaped pad block (6), a trace adjustment screw (7), and a trace adjustment nut (8); The connecting component includes: a screw M6 (9) and a screw M8 (10); The pressing plate (2) and the fixed end of the rectangular support block (3) are processed by slow wire cutting technology, and are drilled after processing; The large L-shaped pad block (4) and the small L-shaped pad block (6) are first ground in the grinding mode, one of the outer end faces is used as a positioning surface, and the two surfaces of the large L-shaped pad block (4) and the small L-shaped pad block (6) are processed in turn by slow wire cutting technology, then the inner end faces are processed in the same way, and after processing, the holes are drilled, reamed and counterbored to ensure the position accuracy and size accuracy of the holes; The medium L-shaped arc pad block (5) is first ground in the grinding mode, one of the inner end faces is used as a positioning surface, and the two surfaces of the medium L-shaped arc pad block (5) are processed in turn by slow wire cutting technology, then the outer end faces are processed in the same way, the two arc surfaces of the outer end faces are symmetric about the central axis of the surface, and after processing, the holes are drilled, reamed and counterbored to ensure the position accuracy and size accuracy of the holes; The workpiece coordinate system zero point establishment method comprises the following steps: ①Fixture installation and workpiece fixation: the pressing plate (2) is fixed on the surface of the test table by the screw M8 (10); the rectangular support block (3) is fixed on the corresponding position of the pressing plate (2) by the screw M6 (9); the bottom surface of the trace feed displacement table is fixed on the rectangular support block (3) by the screw M6 (9); the large L-shaped pad block (4) is fixed on the trace feed displacement table by the screw M6 (9); the medium L-shaped arc pad block (5) is connected with the large L-shaped pad block (4) by the trace adjustment screw (7), and the trace adjustment nut (8) is installed; the workpiece (1) to be processed is adhered to the two inner end faces of the small L-shaped pad block (6) by using paraffin, and after the paraffin cools and solidifies, the small L-shaped pad block (6) is fixed on the medium L-shaped arc pad block (5) by the screw M6 (9), thereby completing the installation of the fixture and the fixation of the workpiece; ②Position adjustment of the workpiece (1) to be processed: the trace adjustment nut (8) is rotated to coarsely adjust the angle of the workpiece (1) to be processed relative to the feed direction of the trace feed displacement table, so that the workpiece (1) to be processed is approximately perpendicular to the feed direction; the angle error is measured by using a dial gauge, the trace adjustment nut (8) is rotated again to make the workpiece (1) to be processed perpendicular to the feed direction, thereby ensuring the cutting depth of the workpiece (1) to be processed and preventing the interference between the fixture and the tool. ③ Zero point establishment of workpiece coordinate system: First, control the feed amount and feed rate of the micro-feed stage to make the fixture and the workpiece (1) to be processed approach the tool equipped with a single abrasive grain along the feed direction; connect the small CCD camera to the computer server terminal, and bring the camera port close to the tool and the workpiece (1) to be processed, adjust the camera position so that it can clearly capture the grinding surface of the workpiece and collect and transmit image information in real time; control the feed amount of the micro-feed stage to 1μm, adjust the feed rate, and continue to make the fixture and the workpiece (1) to be processed move along the feed direction. Through image acquisition, detect and judge whether grinding has occurred on the surface of the tool and the workpiece (1). The specific image detection and zero point establishment method of workpiece coordinate system are as follows: 1) Image preprocessing: The image acquired by the CCD camera is imported into MATLAB. Wavelet thresholding is used to remove discrete noise signals from the image. The grayscale histogram of the image is obtained by using the imhist operator. The grayscale values ​​are modified to enhance the image and improve its recognizability. The theoretically estimated range of the area to be ground in the image is cropped and enlarged to avoid the influence of insufficient light on the edges. 2) Image binarization: The Canny operator is used to binarize the preprocessed image, so that the grinding area appears white and the non-grinding area appears black; 3) Calculate the area of ​​the grinding region: Calculate the area of ​​the white region in the binarized image; when the area is greater than zero, grinding occurs on the workpiece surface, and thus establish the zero-point coordinate system of the workpiece surface grinding. This method for establishing the zero point of the workpiece coordinate system can also be used to establish the zero point of the workpiece surface coordinate system in multi-abrasive grinding.

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