A high-precision and low-runout permanent magnet small ball end polishing head processing method based on small-diameter ball head grinding wheel grinding and dressing

Abstract

The application discloses a high-precision-low-bounce permanent magnet small ball end polishing head processing method based on small-diameter ball head grinding and shape correction, and relates to the technical field of ultra-precision machining. The application is used to solve the problem that the radial bounce of the existing permanent magnet small ball end polishing head is too large in the magnetorheological polishing process, which leads to unstable material removal rate and influences the machining precision and surface quality. The application comprises the following steps: S1, clamping the permanent magnet half-ball end polishing head to the workpiece spindle of a grinding machine, and measuring the bounce of the permanent magnet half-ball end polishing head in a rotating state; S2, clamping the ball head grinding wheel to the tool spindle of the machine, and performing tool measurement by using the ball head grinding wheel; S3, drawing the two-dimensional profile of the permanent magnet half-ball end polishing head, and constructing the machining path of the grinding wheel according to the two-dimensional profile and the measured bounce of the permanent magnet half-ball end polishing head; and S4, performing grinding and shape correction on the permanent magnet half-ball end polishing head. The application can remove the shape error generated in the sintering process of the half-ball end permanent magnet, and further improves the polishing precision.

Description

Technical Field

[0001] This invention relates to the field of ultra-precision machining technology, and more specifically, to a method for machining a high-precision, low-runout permanent magnet small ball end polishing head based on grinding and shaping with a small-diameter ball end grinding wheel. Background Technology

[0002] The permanent magnet spherical end magnetorheological polishing method is a newly emerging ultra-precision special machining method in recent years. This method can perform non-destructive polishing on small-sized, complex structural parts, achieving surface roughness down to the nanometer level and shape accuracy down to the sub-micrometer level or even lower. Parts polished using this method have been applied to various new-generation industrial products, such as hemispherical resonator gyroscopes. The polishing tool used in this method is a specially designed permanent magnet hemispherical end polishing head, which consists of a 4mm diameter, 5mm length hemispherical permanent magnet bonded together with a 3mm diameter, 50mm length cylindrical metal standard plug gauge. During the magnetorheological polishing process, the permanent magnet hemispherical end polishing head does not directly contact the workpiece surface; a certain gap is left between it and the workpiece, allowing the magnetorheological polishing fluid to flow through. The abrasive particles in the magnetorheological polishing fluid continuously shear and scrape the workpiece surface, thereby removing surface material and achieving the polishing effect.

[0003] In magnetorheological polishing, the polishing gap between the permanent magnet hemispherical polishing head and the workpiece surface should remain constant, typically only 100 μm. However, the radial runout of the permanent magnet hemispherical polishing head during rotation can reach 20–30 μm, significantly impacting the polishing gap. During polishing, the polishing gap changes dramatically with the rotation of the permanent magnet hemispherical polishing head, leading to unstable material removal rates, which is detrimental to improving machining accuracy and surface quality, thus affecting the serviceability of the machined parts. Therefore, there is a need to use small-diameter ball-end grinding wheels to grind and reshape the bonded permanent magnet hemispherical polishing head, improving its shape accuracy and reducing radial runout, thereby enhancing polishing quality. Summary of the Invention

[0004] The technical problem to be solved by this invention is:

[0005] Existing permanent magnet ball-end polishing heads exhibit excessive radial runout during magnetorheological polishing, leading to unstable material removal rates and affecting processing accuracy and surface quality.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] This invention provides a method for machining a high-precision, low-runout permanent magnet ball end polishing head based on grinding and shaping with a small-diameter ball end grinding wheel, comprising the following steps:

[0008] S1. Mount the permanent magnet hemispherical polishing head onto the workpiece spindle of the grinding machine tool, and measure the runout of the permanent magnet hemispherical polishing head while it is rotating.

[0009] S2. Clamp the ball-end grinding wheel onto the tool spindle of the machine tool and use the ball-end grinding wheel for tool setting measurement;

[0010] S3. Draw the two-dimensional profile of the permanent magnet hemispherical polishing head, and construct the grinding path of the grinding wheel based on the two-dimensional profile and the measured runout of the permanent magnet hemispherical polishing head, and write the grinding program.

[0011] S4. Execute the grinding process to grind and reshape the permanent magnet hemispherical polishing head.

[0012] Furthermore, S1 includes the following steps:

[0013] S11. Start the grinding machine tool;

[0014] S12. Mount the permanent magnet hemispherical end polishing head onto the workpiece spindle of the machine tool;

[0015] S13. Place the laser displacement sensor on a horizontal worktable and adjust its laser spot to align with the cylindrical surface of the permanent magnet hemispherical polishing head.

[0016] S14. Start the workpiece spindle so that the permanent magnet hemispherical polishing head rotates along the axis.

[0017] S15. Activate the sampling function of the laser displacement sensor, adjust the position of the laser spot, select three different positions on the cylindrical surface of the permanent magnet hemispherical polishing head, measure the runout of each position on the cylindrical surface during the rotation of the permanent magnet hemispherical polishing head, and record the runout value.

[0018] S16. Adjust the laser spot position of the laser displacement sensor, select three different positions on the hemisphere of the permanent magnet hemispherical polishing head, measure the runout of each position on the hemisphere during the rotation of the permanent magnet hemispherical polishing head, and record the runout value.

[0019] S17. Select the maximum value from the measured runout values ​​as the final runout value of the permanent magnet hemispherical end polishing head, and record it as Δr. max .

[0020] Furthermore, S2 includes the following steps:

[0021] S21. Mount the ball-end grinding wheel onto the tool spindle of the machine tool, and adjust the U-axis so that the center of the ball-end grinding wheel is located on the C-axis rotation axis.

[0022] S22. Adjust the high-magnification CCD camera on the horizontal worktable so that the CCD camera lens axis is parallel to the axis of the permanent magnet hemispherical polishing head.

[0023] S23. Under the monitoring of a high-magnification CCD camera, operate the machine tool to move the ball-end grinding wheel above the cylindrical surface of the permanent magnet hemispherical polishing head. Fine-tune the machine tool to ensure the center of the ball-end grinding wheel is directly above the axis of the permanent magnet hemispherical polishing head. Record the coordinate value of the machine tool's X-guide rail at this point as x. i ;

[0024] S24. Operate the machine tool to move the ball-head grinding wheel to the side of the cylindrical surface of the permanent magnet hemispherical polishing head;

[0025] S25. Under the monitoring of a high-magnification CCD camera, the ball center of the ball-end grinding wheel and the axis of the permanent magnet hemispherical polishing head are aligned at the same height by fine-tuning the machine tool.

[0026] S26. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the X-guide rail to reduce the distance between the ball-end grinding wheel and the permanent magnet hemispherical polishing head until the ball-end grinding wheel just contacts the cylindrical surface of the permanent magnet hemispherical polishing head. Record the coordinate values ​​of the X and Z guide rails of the machine tool at this time as x1 and z1, respectively. i ;

[0027] S27. Operate the machine tool to move the ball-head grinding wheel to the other side of the cylindrical surface of the permanent magnet hemispherical polishing head, and keep the center of the ball-head grinding wheel at the same height as the axis of the permanent magnet hemispherical polishing head.

[0028] S28. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the X guide rail to reduce the distance between the ball end grinding wheel and the permanent magnet hemispherical polishing head until the ball end grinding wheel just contacts the cylindrical surface of the permanent magnet hemispherical polishing head. Record the coordinate value of the machine tool X guide rail at this time as x2.

[0029] S29. Operate the machine tool, move the ball-end grinding wheel to a position close to the apex of the polishing head at the end of the permanent magnet hemisphere, and adjust the X and Z guide rail coordinate values ​​to x and Z respectively. i and z i This ensures that the center of the ball-head grinding wheel is at the same height as the axis of the permanent magnet hemispherical polishing head;

[0030] S210. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the Y-guide rail to reduce the distance between the ball-end grinding wheel and the permanent magnet hemispherical polishing head. At the same time, rotate the ball-end grinding wheel by hand until a friction sound is heard. Record the coordinate value of the Y-guide rail of the machine tool at this time as y. i .

[0031] Furthermore, the ball-end grinding wheel mentioned in S21 is a diamond ball-end grinding wheel with an abrasive grit size of W7.

[0032] Furthermore, S3 includes the following steps:

[0033] S31. Determine the diameter of the polishing head at the end of the permanent magnet hemisphere before grinding, i.e.:

[0034] d1 = |x1 - x2|

[0035] S32. Measure the length of the permanent magnet at the hemispherical end and record it as l;

[0036] S33. Draw the two-dimensional outline of the permanent magnet hemispherical polishing head;

[0037] S34. Translate the two-dimensional contour on one side of the axis of the hemispherical permanent magnet outward by a distance h to construct the machining path of the grinding wheel, where the value of h is:

[0038] h = r s +2△r max

[0039] Where, r s The radius of the ball-end grinding wheel;

[0040] S35. Determine the starting point of the grinding process, set compensation instructions based on the processing path, and write the grinding program.

[0041] S36. Import the grinding program into the CNC software of the machine tool.

[0042] Furthermore, S4 includes the following steps:

[0043] S41. Operate the grinding machine tool to move the ball-end grinding wheel to (x i y i , z i )point;

[0044] S42. The clearance between the ball-head grinding wheel and the permanent magnet hemispherical polishing head is controlled to be 2Δr. ma ;

[0045] S43. Control the ball-end grinding wheel to move to the initial point of the machining path;

[0046] S44. Turn on the grinding fluid pump, execute the program, and grind and shape the permanent magnet hemispherical end polishing head along the processing path until grinding is completed.

[0047] Furthermore, in the S44 grinding process, the ball head grinding wheel speed is 60,000 to 80,000 rpm, the permanent magnet hemispherical end polishing head speed is 30 to 60 rpm, and the grinding depth of a single grinding operation is 3 to 5 μm.

[0048] Furthermore, in S44, when the grinding depth reaches 2Δr max At that time, the grinding was completed.

[0049] Furthermore, the grinding machine tool includes: three linear motion axes X, Y, and Z; a C-axis rotary table; two precision fine-tuning linear feed axes U and V; a grinding wheel spindle; and a workpiece spindle. The workpiece spindle's axis is parallel to the Y-axis motion direction. The grinding wheel spindle is obliquely mounted below the C-axis rotary table, with its axis forming a 40° angle with the horizontal plane. The C-axis rotary table's central axis is parallel to the Z-axis, allowing the height of the C-axis rotary table and grinding wheel spindle to be changed along the Z-axis. The U-axis is connected to the rotating end of the C-axis rotary table via a U-axis connecting bracket. One end of the V-axis is mounted on the U-axis connecting bracket, and the other end of the V-axis is connected to the U-axis. A U-axis protective cover is installed on the U-axis.

[0050] Furthermore, the grinding machine tool also includes: a monitoring device, a horizontal worktable, and a workpiece spindle protective cover. The horizontal worktable is located below the ball-end grinding wheel, the workpiece spindle protective cover is installed on the horizontal worktable, the workpiece spindle is installed inside the workpiece spindle protective cover, the horizontal worktable is installed on a two-dimensional moving platform, and the horizontal worktable is operably movable along the X-axis and Y-axis of the grinding machine tool on the two-dimensional moving platform. The monitoring device is installed on the horizontal worktable and includes: a high-magnification CCD camera, which is installed on the horizontal worktable.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] This invention discloses a high-precision, low-runout permanent magnet spherical end polishing head processing method based on small-diameter ball-end grinding wheel shaping. This method can eliminate shape errors generated during the sintering process of hemispherical permanent magnets and solve the problem of uneven magnetic field distribution caused by the irregular shape of the hemispherical permanent magnet. After grinding shaping, the radial runout of the permanent magnet hemispherical end polishing head can be reduced to less than 1μm. This is beneficial for reducing uneven material removal caused by the radial runout of the permanent magnet hemispherical end polishing head during polishing, thereby improving the surface shape accuracy and surface quality of the polished surface.

[0053] The method of this invention is universal and can be used for the shaping of other small rotating machining tools. Attached Figure Description

[0054] Figure 1 This is a flowchart of a high-precision, low-runout permanent magnet ball end polishing head processing method based on small-diameter ball-end grinding and shaping according to an embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of the permanent magnet hemispherical end polishing head grinding and shaping equipment in an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of the placement of the high-magnification CCD camera in an embodiment of the present invention;

[0057] Figure 4 Figure 1 is a schematic diagram of the position of the ball-end grinding wheel in an embodiment of the present invention. In Figure 2a, the center of the ball-end grinding wheel is located directly above the axis of the permanent magnet hemispherical polishing head. In Figure 3b, the ball-end grinding wheel is located on the side of the cylindrical surface of the permanent magnet hemispherical polishing head. In Figure 4c, the ball-end grinding wheel is located on the other side of the cylindrical surface of the permanent magnet hemispherical polishing head. In Figure 5d, the ball-end grinding wheel is located at the apex of the permanent magnet hemispherical polishing head.

[0058] Figure 5 This is a two-dimensional outline diagram of the permanent magnet hemispherical polishing head in an embodiment of the present invention;

[0059] Figure 6 This is a schematic diagram of the movement trajectory of the ball center of the grinding wheel during the grinding process of the ball head by the permanent magnet hemispherical end polishing head in an embodiment of the present invention;

[0060] Figure 7 This is a schematic diagram of the grinding feed in an embodiment of the present invention.

[0061] Explanation of reference numerals in the attached figures:

[0062] 1-C-axis rotary table, 2-U-axis connecting bracket, 3-tool spindle fixing bracket, 4-tool spindle, 5-ball end grinding wheel, 6-horizontal worktable, 7-workpiece spindle protective cover, 8-permanent magnet hemispherical polishing head, 9-workpiece spindle, 10-U-axis protective cover, 11-U-axis, 12-high magnification CCD camera, 13-camera base. Detailed Implementation

[0063] In the description of this invention, it should be noted that the terms "first," "second," and "third" mentioned in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0064] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0065] Specific Implementation Plan 1: (e.g.) Figure 1 As shown, this invention provides a high-precision, low-runout permanent magnet ball-end polishing head machining method based on small-diameter ball-end grinding and shaping, comprising the following steps:

[0066] S1. Mount the permanent magnet hemispherical polishing head onto the workpiece spindle of the grinding machine tool, and measure the runout of the permanent magnet hemispherical polishing head while it is rotating.

[0067] S2. Clamp the ball-end grinding wheel onto the tool spindle of the machine tool and use the ball-end grinding wheel for tool setting measurement;

[0068] S3. Draw the two-dimensional profile of the permanent magnet hemispherical polishing head, and construct the grinding path of the grinding wheel based on the two-dimensional profile and the measured runout of the permanent magnet hemispherical polishing head, and write the grinding program.

[0069] S4. Execute the grinding process to grind and reshape the permanent magnet hemispherical polishing head.

[0070] Specific implementation plan two: S1 includes the following steps:

[0071] S11. Start the grinding machine tool;

[0072] S12. Mount the permanent magnet hemispherical end polishing head onto the workpiece spindle of the machine tool;

[0073] S13. Place the laser displacement sensor on a horizontal worktable and adjust its laser spot to align with the cylindrical surface of the permanent magnet hemispherical polishing head.

[0074] S14. Turn on the workpiece spindle and set the speed to 30-60 rpm to make the permanent magnet hemispherical polishing head rotate along the axis.

[0075] S15. Activate the sampling function of the laser displacement sensor, adjust the position of the laser spot, select three different positions on the cylindrical surface of the permanent magnet hemispherical polishing head, measure the runout of each position on the cylindrical surface during the rotation of the permanent magnet hemispherical polishing head, and record the runout value.

[0076] S16. Adjust the laser spot position of the laser displacement sensor, select three different positions on the hemisphere of the permanent magnet hemispherical polishing head, measure the runout of each position on the hemisphere during the rotation of the permanent magnet hemispherical polishing head, and record the runout value.

[0077] S17. Select the maximum value from the measured runout values ​​as the final runout value of the permanent magnet hemispherical end polishing head, and record it as Δr. max This implementation plan is otherwise the same as Specific Implementation Plan One.

[0078] Specific implementation plan three: S2 includes the following steps:

[0079] S21. Mount the ball-end grinding wheel onto the tool spindle of the machine tool, and adjust the U-axis so that the center of the ball-end grinding wheel is located on the C-axis rotation axis.

[0080] S22, such as Figure 3 As shown, adjust the high-magnification CCD camera on the horizontal worktable so that the axis of the CCD camera lens is parallel to the axis of the permanent magnet hemispherical polishing head.

[0081] S23, such as Figure 4 As shown in Figure a, under the monitoring of a high-magnification CCD camera, the machine tool is operated to move the ball-end grinding wheel above the cylindrical surface of the permanent magnet hemispherical polishing head. By fine-tuning the machine tool, the center of the ball-end grinding wheel is positioned directly above the axis of the permanent magnet hemispherical polishing head, so that the outline of the ball-end grinding wheel and the permanent magnet hemispherical polishing head in the high-magnification CCD camera forms an "8" shape. The coordinate value of the X-axis guideway of the machine tool at this moment is recorded as x. i ;

[0082] S24, such as Figure 4 As shown in b, operate the machine tool to move the ball-head grinding wheel to the side of the cylindrical surface of the permanent magnet hemispherical polishing head;

[0083] S25. Under the monitoring of a high-magnification CCD camera, by fine-tuning the machine tool, the center of the ball end grinding wheel and the axis of the permanent magnet hemispherical polishing head are at the same height, so that the outline of the ball end grinding wheel and the permanent magnet hemispherical polishing head in the high-magnification CCD camera is in the shape of "∞".

[0084] S26. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the X-guide rail to reduce the distance between the ball-end grinding wheel and the permanent magnet hemispherical polishing head until the ball-end grinding wheel just contacts the cylindrical surface of the permanent magnet hemispherical polishing head. Record the coordinate values ​​of the X and Z guide rails of the machine tool at this time as x1 and z1, respectively. i ;

[0085] S27, such as Figure 4 As shown in c, operate the machine tool to move the ball-head grinding wheel to the other side of the cylindrical surface of the permanent magnet hemispherical polishing head, and keep the center of the ball-head grinding wheel at the same height as the axis of the permanent magnet hemispherical polishing head;

[0086] S28. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the X guide rail to reduce the distance between the ball end grinding wheel and the permanent magnet hemispherical polishing head until the ball end grinding wheel just contacts the cylindrical surface of the permanent magnet hemispherical polishing head. Record the coordinate value of the machine tool X guide rail at this time as x2.

[0087] S29, such as Figure 4 As shown in d, operate the machine tool and move the ball-end grinding wheel to a position close to the apex of the polishing head at the end of the permanent magnet hemisphere. Adjust the X and Z guide rail coordinate values ​​to x and y respectively. i and z i This ensures that the center of the ball-head grinding wheel is at the same height as the axis of the permanent magnet hemispherical polishing head;

[0088] S210. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the Y-guide rail to reduce the distance between the ball-end grinding wheel and the permanent magnet hemispherical polishing head. At the same time, rotate the ball-end grinding wheel by hand until a friction sound is heard. At this point, the ball-end grinding wheel just contacts the apex of the permanent magnet hemispherical polishing head. Record the coordinate value of the Y-guide rail of the machine tool at this moment as y. iThis implementation plan is otherwise the same as Implementation Plan Two.

[0089] Specific Implementation Scheme Four: The ball-end grinding wheel mentioned in S21 is a diamond ball-end grinding wheel with a diameter of 3.8 mm and an abrasive grit size of W7. All other aspects of this implementation scheme are the same as Specific Implementation Scheme Three.

[0090] Specific implementation plan five: S3 includes the following steps:

[0091] S31. Determine the diameter of the polishing head at the end of the permanent magnet hemisphere before grinding, i.e.:

[0092] d1 = |x1 - x2|

[0093] S32. Use vernier calipers to measure the length of the permanent magnet at the hemispherical end and record it as l;

[0094] S33, such as Figure 5 As shown, the two-dimensional outline of the permanent magnet hemispherical polishing head is drawn in the two-dimensional drawing software CAD. The rod of the permanent magnet hemispherical polishing head is a standard plug gauge with a diameter of 3mm, which does not need to be machined.

[0095] S34. Because the center of the ball-end grinding wheel and the axis of the permanent magnet hemispherical polishing head are always at the same height during the grinding process, and the permanent magnet hemispherical polishing head rotates continuously along its own axis during grinding, the ball-end grinding wheel only needs to move on one side of the hemispherical permanent magnet. Therefore, as Figure 6 As shown, the two-dimensional contour on one side of the permanent magnet axis at the hemispherical end is translated outward by a distance h, i.e., segments BC and CD in the figure. A 1mm long line segment is then drawn along the tangent direction at points B and D, as shown in segments AB and DE in the figure, to construct the machining path of the grinding wheel. The value of h is:

[0096] h = r s +2△r max

[0097] Where, r s The radius of the ball-end grinding wheel;

[0098] In CAD, set point B in the drawing as the origin of the coordinate system, and then export the coordinates of points A, C, D, and E.

[0099] S35. Point A is determined as the starting point of the grinding process. The ball-end grinding wheel's center moves sequentially along trajectories AB, BC, CD, and DE to point E. Based on the machining path, a compensation command is set to feed a certain distance along the normal direction of the motion trajectory. This feed distance is the grinding depth, thus obtaining a new motion trajectory. Figure 7As shown. Write another grinding program in sequence: After the feed is completed, take point E' as the starting point of the grinding process, and move the center of the ball end grinding wheel along the trajectory E'D', D'C', C'B', B'A' to point A' in sequence, and write the grinding program; by adding loop instructions to the program and continuously increasing the grinding depth, the grinding process can be completed.

[0100] S36. Import the grinding program into the machine tool's CNC software. This implementation plan is otherwise the same as specific implementation plan four.

[0101] Specific implementation plan six: S4 includes the following steps:

[0102] S41. Operate the grinding machine tool to move the ball-end grinding wheel to (x i y i , z i The point is where the ball-head grinding wheel just contacts the apex of the permanent magnet hemispherical polishing head;

[0103] S42. Operate the machine tool; the distance the machine tool's Y-guide rail moves is 2Δr. max The free travel allowance between the ball-head grinding wheel and the permanent magnet hemispherical polishing head is controlled to be 2Δr. ma And set the current position as the origin of the machine tool coordinate system;

[0104] S43. Operate the machine tool and control the ball-end grinding wheel to move to the initial point of the machining path;

[0105] S44. Move the ball-end grinding wheel to the initial point of its trajectory, i.e., point A. Turn on the grinding fluid pump, execute the program, and grind and shape the permanent magnet hemispherical end polishing head along the machining path until grinding is complete. The rest of this implementation plan is the same as in specific implementation plan five.

[0106] Specific Implementation Scheme Seven: In the S44 grinding process, the ball end grinding wheel speed is 60,000–80,000 rpm, the permanent magnet hemispherical end polishing head speed is 30–60 rpm, and the grinding depth in a single grinding pass is 3–5 μm. All other aspects of this implementation scheme are the same as in Specific Implementation Scheme Six.

[0107] Specific implementation plan eight: In S44, when the grinding depth reaches 2Δr max At this time, the grinding is completed. All other aspects of this implementation plan are the same as those in Specific Implementation Plan Seven.

[0108] Specific Implementation Plan Nine: (e.g.) Figure 2As shown, the grinding machine tool includes: three linear motion axes X, Y, and Z; a C-axis rotary table; two precision fine-tuning linear feed axes U and V; a grinding wheel spindle; and a workpiece spindle. The workpiece spindle's axis is parallel to the Y-axis motion direction. The grinding wheel spindle is obliquely mounted below the C-axis rotary table, with its axis forming a 40° angle with the horizontal plane. The C-axis rotary table's central axis is parallel to the Z-axis, allowing the height of the C-axis rotary table and grinding wheel spindle to be adjusted along the Z-axis. The U-axis is connected to the rotating end of the C-axis rotary table via a U-axis connecting bracket. One end of the V-axis is mounted on the U-axis connecting bracket, and the other end of the V-axis is connected to the U-axis. A U-axis protective cover is installed on the U-axis. Other aspects of this embodiment are the same as in specific embodiment one.

[0109] Specific Implementation Scheme Ten: The grinding machine tool further includes: a monitoring device, a horizontal worktable, and a workpiece spindle protective cover. The horizontal worktable is located below the ball-end grinding wheel. The workpiece spindle protective cover is installed on the horizontal worktable, and the workpiece spindle is installed inside the workpiece spindle protective cover. The horizontal worktable is installed on a two-dimensional moving platform, and the horizontal worktable is operably movable along the X-axis and Y-axis of the grinding machine tool on the two-dimensional moving platform. The monitoring device is installed on the horizontal worktable and includes: a high-magnification CCD camera, which is installed on the horizontal worktable. The rest of this implementation scheme is the same as Specific Implementation Scheme Nine.

[0110] Example 1

[0111] To verify the effectiveness of the method of the present invention, a specific embodiment of the present invention is provided below.

[0112] The experiment was conducted using the method of the present invention. In the experiment, the sampling frequency of the laser displacement sensor for measuring the runout of the permanent magnet hemispherical polishing head was set to 392kHz, and the rotational speed of the workpiece spindle was set to 30rpm.

[0113] The runout at three different positions on the cylindrical surface during the rotation of the permanent magnet hemispherical polishing head was measured to be 18.3 μm, 15.7 μm, and 19.0 μm, respectively; the runout at three positions on the hemispherical surface during the rotation of the permanent magnet hemispherical polishing head was measured to be 10.7 μm, 11.6 μm, and 8.2 μm, respectively; 19.0 μm was selected as the final runout of the permanent magnet hemispherical polishing head and recorded as Δr. max .

[0114] The obtained coordinate value x i 73.092mm, y i -32.308mm and z i The diameter is 11.293mm, and x1 is 75.110mm and x2 is 71.078mm.

[0115] The diameter of the polishing head at the end of the permanent magnet hemisphere before grinding is:

[0116] d1 = |x1 - x2| = 4.032 mm

[0117] Meanwhile, the length l of the permanent magnet at the hemispherical end was measured to be 5.042 mm using vernier calipers;

[0118] The value of h can be:

[0119] h = r s +2△r max =1.938mm

[0120] Turn on the grinding fluid pump, set the ball-end grinding wheel speed to 70,000 rpm, set the permanent magnet hemispherical polishing head speed to 60 rpm, and set the grinding depth for a single pass to 3 μm. When the tool compensation distance reaches 0.076 mm, i.e., the grinding depth reaches 0.038 mm, the program ends, and the grinding is complete.

[0121] The runout of the permanent magnet hemispherical polishing head after grinding and shaping was measured to be only 0.7μm, which is much lower than the runout of the unground permanent magnet hemispherical polishing head, which is about 17μm.

[0122] Example 2

[0123] Polishing experiments were conducted on the ground fused silica rod workpiece using the polishing head with the ground and modified permanent magnet hemispherical end obtained in Example 1 and the polishing head without the ground and modified permanent magnet hemispherical end. The polishing process parameters were set as follows: polishing head speed 8000 rpm, workpiece speed 60 rpm, and polishing gap 0.1 mm.

[0124] The polishing results are as follows: the surface accuracy (PV) of the workpiece polished with the grinding-trimmed permanent magnet hemispherical polishing head is 0.10 μm, and the roughness (Sa) is 12 nm; while the surface accuracy (PV) of the workpiece polished with the un-grinded permanent magnet hemispherical polishing head is 0.13 μm, and the roughness (Sa) is 14.5 nm.

[0125] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for machining a high-precision, low-runout permanent magnet small ball end polishing head based on grinding and shaping with a small-diameter ball-end grinding wheel, characterized in that... Includes the following steps: S1. Mount the permanent magnet hemispherical polishing head onto the workpiece spindle of the grinding machine tool, and measure the runout of the permanent magnet hemispherical polishing head while it is rotating. S2. Clamp the ball-end grinding wheel onto the tool spindle of the machine tool and use the ball-end grinding wheel for tool setting measurement; S3. Draw the two-dimensional profile of the permanent magnet hemispherical polishing head, and construct the grinding path of the grinding wheel based on the two-dimensional profile and the measured runout of the permanent magnet hemispherical polishing head, and write the grinding program. S4. Perform the grinding process to grind and reshape the permanent magnet hemispherical end polishing head. S2 includes the following steps: S21. Mount the ball-end grinding wheel onto the tool spindle of the machine tool, and adjust the U-axis so that the center of the ball-end grinding wheel is located on the C-axis rotation axis. S22. Adjust the high-magnification CCD camera on the horizontal worktable so that the CCD camera lens axis is parallel to the axis of the permanent magnet hemispherical polishing head. S23. Under the monitoring of a high-magnification CCD camera, operate the machine tool to move the ball-end grinding wheel above the cylindrical surface of the permanent magnet hemispherical polishing head. Fine-tune the machine tool to ensure the center of the ball-end grinding wheel is directly above the axis of the permanent magnet hemispherical polishing head. Record the coordinate value of the machine tool's X-guide rail at this point as x. i ; S24. Operate the machine tool to move the ball-head grinding wheel to the side of the cylindrical surface of the permanent magnet hemispherical polishing head; S25. Under the monitoring of a high-magnification CCD camera, the ball center of the ball-end grinding wheel and the axis of the permanent magnet hemispherical polishing head are aligned at the same height by fine-tuning the machine tool. S26. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the X-guide rail to reduce the distance between the ball-end grinding wheel and the permanent magnet hemispherical polishing head until the ball-end grinding wheel just contacts the cylindrical surface of the permanent magnet hemispherical polishing head. Record the coordinate values ​​of the X and Z guide rails of the machine tool at this time as x1 and z1, respectively. i ; S27. Operate the machine tool to move the ball-head grinding wheel to the other side of the cylindrical surface of the permanent magnet hemispherical polishing head, and keep the center of the ball-head grinding wheel at the same height as the axis of the permanent magnet hemispherical polishing head. S28. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the X guide rail to reduce the distance between the ball end grinding wheel and the permanent magnet hemispherical polishing head until the ball end grinding wheel just contacts the cylindrical surface of the permanent magnet hemispherical polishing head. Record the coordinate value of the machine tool X guide rail at this time as x2. S29. Operate the machine tool, move the ball-end grinding wheel to a position close to the apex of the polishing head at the end of the permanent magnet hemisphere, and adjust the X and Z guide rail coordinate values ​​to x and Z respectively. i and z i This ensures that the center of the ball-head grinding wheel is at the same height as the axis of the permanent magnet hemispherical polishing head; S210. Under the monitoring of a high-magnification CCD camera, operate the machine tool and move the Y-guide rail to reduce the distance between the ball-end grinding wheel and the permanent magnet hemispherical polishing head. At the same time, rotate the ball-end grinding wheel by hand until a friction sound is heard. Record the coordinate value of the Y-guide rail of the machine tool at this time as y. i ; S3 includes the following steps: S31. Determine the diameter of the polishing head at the end of the permanent magnet hemisphere before grinding, i.e.: d1 = |x1 - x2| S32. Measure the length of the permanent magnet at the hemispherical end and record it as l; S33. Draw the two-dimensional outline of the permanent magnet hemispherical polishing head; S34. Translate the two-dimensional contour on one side of the axis of the hemispherical permanent magnet outward by a distance h to construct the machining path of the grinding wheel, where the value of h is: h= r s +2△r max Where, r s Let Δr be the radius of the ball-end grinding wheel. max The maximum value selected from the measured bounce; S35. Determine the starting point of the grinding process, set compensation instructions based on the processing path, and write the grinding program. S36. Import the grinding program into the CNC software of the machine tool; S4 includes the following steps: S41. Operate the grinding machine tool to move the ball-end grinding wheel to (x) i y i , z i )point; S42. The clearance between the ball-head grinding wheel and the permanent magnet hemispherical polishing head is controlled to be 2Δr. max ; S43. Control the ball-end grinding wheel to move to the initial point of the machining path; S44. Turn on the grinding fluid pump, execute the program, and grind and shape the permanent magnet hemispherical end polishing head along the processing path until grinding is completed.

2. The high-precision, low-runout permanent magnet ball end polishing head processing method based on small-diameter ball-end grinding and shaping according to claim 1, characterized in that, S1 includes the following steps: S11. Start the grinding machine tool; S12. Mount the permanent magnet hemispherical end polishing head onto the workpiece spindle of the machine tool; S13. Place the laser displacement sensor on a horizontal worktable and adjust its laser spot to align with the cylindrical surface of the permanent magnet hemispherical polishing head. S14. Start the workpiece spindle so that the permanent magnet hemispherical end polishing head rotates along the axis; S15. Activate the sampling function of the laser displacement sensor, adjust the position of the laser spot, select three different positions on the cylindrical surface of the permanent magnet hemispherical polishing head, measure the runout of each position on the cylindrical surface during the rotation of the permanent magnet hemispherical polishing head, and record the runout value. S16. Adjust the laser spot position of the laser displacement sensor, select three different positions on the hemisphere of the permanent magnet hemispherical polishing head, measure the runout of each position on the hemisphere during the rotation of the permanent magnet hemispherical polishing head, and record the runout value. S17. Select the maximum value from the measured runout values ​​as the final runout value Δr of the permanent magnet hemispherical polishing head. max .

3. The high-precision, low-runout permanent magnet ball end polishing head processing method based on small-diameter ball-end grinding and shaping according to claim 2, characterized in that, The ball-end grinding wheel mentioned in S21 is a diamond ball-end grinding wheel with an abrasive grit size of W7.

4. The high-precision, low-runout permanent magnet ball end polishing head processing method based on small-diameter ball-end grinding and shaping according to claim 3, characterized in that, In the S44 grinding process, the ball head grinding wheel speed is 60,000~80,000 rpm, the permanent magnet hemispherical end polishing head speed is 30~60 rpm, and the grinding depth of a single grinding is 3~5 μm.

5. The high-precision, low-runout permanent magnet ball end polishing head processing method based on small-diameter ball-end grinding and shaping according to claim 4, characterized in that, In S44, when the grinding depth reaches 2Δr max At that time, the grinding was completed.

6. The high-precision, low-runout permanent magnet ball end polishing head processing method based on small-diameter ball-end grinding and shaping according to claim 1, characterized in that, The grinding machine tool includes: three linear motion axes X, Y, and Z; a C-axis rotary table; two precision fine-tuning linear feed axes U and V; a grinding wheel spindle; and a workpiece spindle. The workpiece spindle's axis is parallel to the Y-axis motion direction. The grinding wheel spindle is obliquely mounted below the C-axis rotary table, with its axis at a 40° angle to the horizontal plane. The C-axis rotary table's central axis is parallel to the Z-axis, allowing the height of the C-axis rotary table and grinding wheel spindle to be adjusted along the Z-axis. The U-axis is connected to the rotating end of the C-axis rotary table via a U-axis connecting bracket. One end of the V-axis is mounted on the U-axis connecting bracket, and the other end of the V-axis is connected to the U-axis. A U-axis protective cover is installed on the U-axis.

7. The high-precision, low-runout permanent magnet ball end polishing head processing method based on small-diameter ball-end grinding and shaping according to claim 6, characterized in that, The grinding machine tool further includes: a monitoring device, a horizontal worktable, and a workpiece spindle protective cover. The horizontal worktable is located below the ball-end grinding wheel. The workpiece spindle protective cover is installed on the horizontal worktable, and the workpiece spindle is installed inside the workpiece spindle protective cover. The horizontal worktable is installed on a two-dimensional moving platform, and the horizontal worktable is operably movable along the X-axis and Y-axis of the grinding machine tool on the two-dimensional moving platform. The monitoring device is installed on the horizontal worktable and includes: a high-magnification CCD camera, which is installed on the horizontal worktable.

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