An ultra-precision grinding processing method for reducing edge collapse of a hemispherical resonator end face

Abstract

The application provides a kind of ultra-precision grinding processing method for reducing the edge collapse of hemispherical resonator end face, and relates to the technical field of ultra-precision machining, to solve the problem that sub-surface damage in the hemispherical resonator lip chamfer processing process cannot be completely removed or edge collapse occurs. In the chamfering process of ultra-precision grinding processing of hemispherical resonator, the modification process of grinding wheel ball center trajectory according to the total grinding depth d of hemispherical resonator lip chamfer in ultra-precision grinding process and the sub-surface damage depth SSD of hemispherical resonator blank is included. If d<SSD, the end face is ground, and the cumulative grinding depth is AP. After grinding, the end face grinding track in the grinding wheel ball center track A2 is offset to the inside of the entity by Ap, and the iteration operation is performed until d≥SSD. Finally, the grinding wheel ball center track of hemispherical resonator ultra-precision grinding processing containing chamfer is obtained. The method is used for ultra-precision grinding processing of hemispherical resonator to obtain high-quality hemispherical resonator.

Description

Technical Field

[0001] This invention relates to the field of ultra-precision machining technology, and more specifically, to an ultra-precision grinding method for reducing edge chipping on the end face of a hemispherical resonator. Background Technology

[0002] The hemispherical resonator, a key component used in weaponry, satellite navigation, aerospace, and other fields, is a typical complex thin-walled curved surface component made of fused silica. Machining this workpiece typically employs rough grinding, ultra-precision grinding, and polishing processes to meet its dimensional and positional accuracy requirements. However, due to its unique structural features and material properties, the end face (the plane containing the lip of the hemispherical shell) of the hemispherical resonator is highly susceptible to chipping during grinding. Figure 1 As shown in (a). Therefore, the end lip of the hemispherical harmonic oscillator is chamfered during the blank forming stage, as shown in (a). Figure 1 As shown in (b). Currently, the common practice for chamfering the end face of a hemispherical resonator blank is to perform chamfering on a separate machine tool after the inner and outer surfaces of the hemispherical resonator have been formed. Due to secondary clamping and tool setting errors, the size of the chamfer at the end face lip is uncontrollable. In subsequent ultra-precision grinding, when the initial chamfer of the hemispherical resonator blank lip is large, the grinding process cannot completely remove the chamfer. The subsurface damage caused by the chamfer cannot be completely removed by the subsequent polishing process, resulting in a large number of surface cracks in the chamfered area, such as... Figure 2 As shown. When the lip of the hemispherical harmonic oscillator blank has no initial chamfer or the initial chamfer size is small, chipping is prone to occur during the feed and retraction processes on the end face as the grinding depth increases, such as... Figure 3 As shown. To improve the quality of the lip of a hemispherical resonator, on the one hand, it is necessary to completely remove the subsurface damage caused by the chamfering of the lip during the forming process of the hemispherical resonator blank, that is, to reduce the chamfer size of the blank; on the other hand, when the chamfer size is too small or disappears, chipping will occur during the grinding of the end face. Therefore, it is necessary to add the grinding trajectory of the lip chamfer to the grinding trajectory of the inner and outer surfaces of the hemispherical resonator. This allows the end face and the inner and outer spherical surfaces to be ground in one go, achieving controllable machining of the chamfer size of the hemispherical resonator lip. Summary of the Invention:

[0003] The technical problem to be solved by this invention is:

[0004] Existing methods for chamfering the lip of hemispherical harmonic oscillators cannot effectively control the quality of the chamfering process, and are prone to problems such as incomplete removal of subsurface damage in the chamfered area or edge chipping.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] The application provides an ultra-precision grinding processing method for reducing edge collapse of a hemispherical resonator end face, and comprises the following steps:

[0007] Step S1: a machine tool coordinate system is established, a ball head grinding wheel is clamped to a grinding wheel main shaft, a ball center position of the ball head grinding wheel is observed through a CCD camera and a magnifying lens, a hemispherical resonator size is measured, a cross-sectional profile line intersecting a rotation axis is drawn in drawing software, and is recorded as a hemispherical resonator rough profile A0; and a grinding wheel ball center trajectory A1 when the grinding wheel is tangent to the workpiece is further constructed;

[0008] Step S2: a trial cutting point is selected based on the grinding wheel ball center trajectory A1;

[0009] Step S3: the hemispherical resonator is clamped to the workpiece main shaft, tool setting is performed by means of the CCD camera, and a machine tool coordinate origin is calibrated;

[0010] Step S4: the machine tool is operated, the ball center of the ball head grinding wheel is close to each trial cutting point for trial cutting, coordinate values between the trial cutting points and the machine tool coordinate origin are recorded, and a corrected trial cutting point is obtained; the grinding wheel ball center trajectory A1 is corrected based on the corrected trial cutting point, and a corrected grinding wheel ball center trajectory A2 is obtained;

[0011] Step S5: a chamfering process is performed on a grinding trajectory of the hemispherical resonator end face, and a hemispherical resonator ultra-precision grinding processing grinding wheel ball center trajectory containing a chamfer is obtained, comprising the following steps:

[0012] Step S5-1: the corrected grinding wheel ball center trajectory A2 is offset by a distance r towards the inside of the workpiece entity, and a theoretical profile A3 before hemispherical resonator ultra-precision grinding is obtained; the corrected grinding wheel ball center trajectory A2 is offset by a distance r+D towards the inside of the workpiece entity, and a theoretical profile A4 after hemispherical resonator ultra-precision grinding is obtained, wherein D is a total grinding depth of the hemispherical resonator ultra-precision grinding processing;

[0013] Step S5-2: a chamfering process is performed on the intersection of the end face and the inner and outer spherical surface on the theoretical profile A4 after hemispherical resonator ultra-precision grinding processing, the chamfer is recorded as C0, and a theoretical profile A4 after hemispherical resonator ultra-precision grinding containing a chamfer is obtained;

[0014] Step S5-3: the lip chamfer of the workpiece before grinding is observed by means of the CCD camera, the actual size of each pixel point in the image is measured, the actual size of the lip chamfer of the hemispherical resonator rough profile is measured, and a 45° chamfering process is performed on the end face of the theoretical profile A3 before hemispherical resonator ultra-precision grinding, and is recorded as a chamfer C1;

[0015] Step S5-4: the vertical distance d between the chamfer C0 and the chamfer C1 is measured, and the distance d corresponds to the total grinding depth of the hemispherical resonator lip chamfer in the ultra-precision grinding process;

[0016] Step S5-5: comparing the size of d with the sub-surface damage depth SSD of the hemispherical resonator blank, if d < SSD, grinding the end face, the cumulative grinding depth is AP, after grinding, the end face grinding track in the ball center track A2 is offset to the inside of the entity by AP;

[0017] Step S5-6: repeating the operations of steps S5-1 to S5-5 until d ≥ SSD, correcting the theoretical profile A4 of the hemispherical resonator after the ultra-precision grinding with chamfering;

[0018] Step S5-7: offsetting the corrected theoretical profile A4 of the hemispherical resonator after the ultra-precision grinding with chamfering to the outside of the workpiece entity by a distance of r+D+a, obtaining the ball center track A5 of the grinding wheel for the hemispherical resonator ultra-precision grinding with chamfering, wherein a is the tool setting error and the grinding allowance;

[0019] Step S5-8: if the shortest distance d between the chamfering area of the ball center track A5 of the grinding wheel and the chamfering area of the theoretical profile A3 before the hemispherical resonator ultra-precision grinding min ≤ r+δ max , δ max is the maximum runout of the ball head grinding wheel, then a = a+0.01mm, and the steps S5-7 to S5-8 are repeatedly executed until d min > r+δ max ; if d min > r+δ max , the step is ended;

[0020] Step S6: using the ball center track A5 of the grinding wheel for the hemispherical resonator ultra-precision grinding with chamfering to machine the hemispherical resonator with lip chamfering.

[0021] Further, the step S1 includes the following steps:

[0022] Step S1-1: establishing a machine tool coordinate system, the machine tool horizontal worktable and the XOY plane are parallel, the workpiece spindle and the X axis are perpendicular and the Y axis is parallel;

[0023] Step S1-2: clamping the ball head grinding wheel to the grinding wheel spindle, setting the grinding wheel spindle speed, and measuring the maximum runout δ max of the ball head grinding wheel using a laser displacement sensor, so that the maximum runout is less than 5μm, if the runout exceeds 5μm, the step is repeated to re-clamp;

[0024] Step S1-3: observing the ball center position of the ball head grinding wheel through a CCD camera and a magnifying lens, adjusting the ball center position of the ball head grinding wheel to be on the center line of the C-axis rotary table through linear motion along the U-axis, and operating the machine tool to move the Z-axis so that the ball center height of the ball head grinding wheel is consistent with the height of the grinding wheel spindle rotary axis.

[0025] Step S1-4: Use a coordinate measuring machine to measure the dimensions of the hemispherical harmonic oscillator, and draw the cross-sectional outline through the axis of rotation in the drafting software, which is recorded as the hemispherical harmonic oscillator blank outline A0;

[0026] Step S1-5: Offset the contour line on one side of the rotation axis of the hemispherical harmonic oscillator blank by a distance r in the direction of the outside of the solid, where r is the radius of the ball head grinding wheel, to obtain the trajectory A1 of the grinding wheel center when the grinding wheel is tangent to the workpiece.

[0027] Furthermore, the method for selecting the trial cutting points in step S2 is as follows: select one point on each straight line machining trajectory and the circular arc machining trajectory with a radius less than or equal to 2mm on each segment of the grinding wheel ball center trajectory A1; select two points on each circular arc machining trajectory with a radius greater than 2mm, and the length of the circular arc machining trajectory between the two points is not less than 1 / 2 of the length of the circular arc machining trajectory segment.

[0028] Further, step S3 includes the following steps:

[0029] Step S3-1: Mount the hemispherical resonator on the workpiece spindle and use a dial indicator to measure the radial runout of the workpiece at different positions, keeping the runout between 0 and 5 μm. If the runout exceeds 5 μm, repeat this step and re-clamp the workpiece.

[0030] Step S3-2: Use a CCD camera to perform tool setting. Based on the relative positions of the grinding wheel and the workpiece spindle in the machine tool coordinate system, operate the machine tool and move the X-axis so that the center of the ball end grinding wheel coincides with the rotation axis of the workpiece spindle; move the Y-axis so that the ball end grinding wheel just contacts the end face of the inner rod of the hemispherical harmonic oscillator.

[0031] Step S3-3: Operate the machine tool to move the grinding wheel ball center away from the workpiece along the Y-axis, and move the worktable along the negative X-axis. Set the X-axis coordinate and Y-axis coordinate of this position as the origin of the machine tool coordinate system.

[0032] Step S3-4: Measure the X and Y coordinate values ​​between each trial cutting point and the origin of the machine tool coordinate system.

[0033] Further, step S4 includes the following process:

[0034] Step S4-1: The grinding trajectory of the hemispherical harmonic oscillator is divided into 7 parts: inner rod, inner fillet, inner spherical surface, end face, outer spherical surface, outer fillet, and outer rod. The trial cutting sequence is: inner spherical surface → inner rod → inner fillet → outer spherical surface → outer rod → outer fillet → end face;

[0035] Step S4-2: Operate the machine tool to bring the center of the ball end grinding wheel close to the test cutting point for a test cut;

[0036] Step S4-3: Manually rotate the ball head grinding wheel and the workpiece. If no grinding sound is produced, repeat step S4-2. If periodic grinding sound is produced, proceed directly to step S4-4.

[0037] Step S4-4: Record the X and Y coordinate values ​​between the current test cutting point and the machine tool coordinate origin;

[0038] Step S4-5: Operate the machine tool, move the center of the ball of the ball-end grinding wheel to the next test cutting point, and repeat the operation of steps S4-2 to S4-4 until all test cutting points are corrected;

[0039] Step S4-6: Based on the corrected trial cutting points, correct the grinding wheel ball center trajectory A1 to obtain the corrected grinding wheel ball center trajectory A2.

[0040] Furthermore, the chamfer C0 dimension described in step S5-2 is 15-30 μm.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] This invention provides an ultra-precision grinding method to reduce edge chipping on the end face of a hemispherical resonator, ensuring the chamfer size is between 15-20 μm and controlling the total grinding depth of the hemispherical resonator lip chamfer during ultra-precision grinding to be greater than or equal to the subsurface damage depth (SSD) of the blank. This effectively solves the problem of edge chipping on the end face of the hemispherical resonator during grinding and significantly reduces the subsurface damage of the hemispherical resonator blank lip chamfer, greatly improving the processing quality of such workpieces and helping to improve the efficiency of subsequent polishing and other processing of such workpieces.

[0043] The method of this invention has a certain degree of universality and can be extended to the efficient, low-damage, high-quality ultra-precision grinding of small-diameter (φ20-φ50mm) rotating thin-walled workpieces with a thickness of less than 1mm. Attached Figure Description

[0044] Figure 1 This is a physical diagram of the end face of the hemispherical harmonic oscillator in the background art of this invention;

[0045] Figure 2 This is a defect in the background art of the present invention where the chamfered edge of the polished lip was not completely removed, leaving residual residue;

[0046] Figure 3 This refers to the chipping of the lip edge during ultra-precision grinding in the background art of this invention;

[0047] Figure 4 This is a schematic diagram of the processing equipment structure in an embodiment of the present invention;

[0048] Figure 5 This is a diagram of the grinding wheel's motion trajectory in an embodiment of the present invention;

[0049] Figure 6 This is a diagram showing the relationship between the trajectory of the grinding wheel's center and the theoretical profile of the hemispherical harmonic oscillator in an embodiment of the present invention.

[0050] Figure 7 This is a comparison image of the contour of the hemispherical harmonic oscillator before and after ultra-precision grinding in an embodiment of the present invention;

[0051] Figure 8 This is a modified theoretical outline diagram of the hemispherical harmonic oscillator in an embodiment of the present invention;

[0052] Figure 9 This is a diagram showing the trajectory of the grinding wheel center during ultra-precision grinding of a hemispherical harmonic oscillator with chamfered lip in an embodiment of the present invention.

[0053] Figure 10 This is a physical image of the chamfered lip of the hemispherical harmonic oscillator in an embodiment of the present invention.

[0054] Explanation of reference numerals in the attached figures:

[0055] 1-C-axis rotary table; 2-U-axis connecting frame; 3-V-axis; 4-grinding wheel spindle fixing frame; 5-grinding wheel spindle; 6-ball end grinding wheel; 7-horizontal worktable; 8-workpiece spindle protective cover; 9-workpiece; 10-workpiece spindle; 11-U-axis protective cover; 12-U-axis. Detailed Implementation

[0056] In the description of this invention, it should be noted that the terms used in the various embodiments, such as "upper," "lower," "front," "rear," "left," and "right," which indicate orientation, are only used to simplify the description of the positional relationships based on the accompanying drawings and do not mean that the components and devices referred to must be operated in accordance with the specific orientations and defined operations, methods, and structures in the specification. Such directional terms do not constitute a limitation of this invention.

[0057] 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.

[0058] 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.

[0059] like Figure 4As shown, the hemispherical resonator grinding apparatus used in this embodiment includes three linear motion axes X, Y, and Z, a C-axis rotary table 1, two precision fine-tuning linear feed axes U-axis 12 and V-axis 3, a grinding wheel spindle 5, and a workpiece spindle 10. A horizontal worktable 7 is mounted on a two-dimensional moving platform, and the control system controls the horizontal worktable 7 to move horizontally along the X and Y axes on the two-dimensional moving platform. The workpiece spindle 10 is equipped with a workpiece spindle protective cover 8, which is mounted on the upper surface of the horizontal worktable 7. The axial direction of the workpiece spindle 10 is parallel to the Y axis. The C-axis rotation direction is as follows: the central axis of the C-axis rotary table 1 is parallel to the Z-axis, and its movement along the Z-axis changes the height of the grinding wheel spindle 5. The grinding wheel spindle 5 is obliquely mounted below the U-axis 12 via the grinding wheel spindle fixing bracket 4, and the angle between the axis of the grinding wheel spindle 5 and the horizontal plane is 40°. The U-axis 12 is equipped with a U-axis protective cover 11 and is rigidly connected to the C-axis rotary table 1 via the U-axis connecting bracket 2. The V-axis 3 is mounted below the C-axis rotary table 1, and its lower end is connected to the grinding wheel spindle fixing bracket 4. The grinding wheel spindle 5 is finely adjusted in the Y-axis and X-axis directions via the U-axis 12 and V-axis 3. During the grinding process of the hemispherical harmonic oscillator, the ball-end grinding wheel 6 will move along the contour line of the workpiece 9. According to the different surface features of each segment of the workpiece 9, the grinding wheel rotation angle of each segment is changed to prevent interference between the workpiece 9 and the ball-end grinding wheel 6.

[0060] During grinding, the relative grinding speed between the workpiece 9 and the grinding wheel is adjusted by changing the rotational speeds of the workpiece spindle 10 and the grinding wheel spindle 5. The feed speed of the workpiece 9 and the grinding wheel is adjusted by controlling the movement speed of the two-dimensional moving platform. The machine tool motion system controls the tool radius compensation value to complete the feed motion of the ball end grinding wheel 6, thereby adjusting the grinding depth. For the feed of the arc machining contour, the unoffset arc machining contour trajectory is offset by the tool compensation value along the line connecting the center point of the arc and all points on the arc segment; for the feed of the straight machining contour, the unoffset straight machining contour trajectory is offset by the tool compensation value along the direction closer to the solid of the workpiece 9. The machine tool motion system controls the horizontal worktable 7 to move along the X and Y axes of the machine tool, thereby changing the position of the workpiece 9 relative to the ball end grinding wheel 6 to achieve the feed motion of the ball end grinding wheel 6.

[0061] Specific Implementation Scheme 1: This invention provides an ultra-precision grinding method for reducing edge chipping on the end face of a hemispherical resonator, comprising the following steps:

[0062] Step S1: Establish the machine tool coordinate system, clamp the ball-end grinding wheel onto the grinding wheel spindle, observe the position of the ball center of the ball-end grinding wheel through a CCD camera and magnifying lens, measure the size of the hemispherical harmonic oscillator, draw the cross-sectional outline through the axis of rotation in CAD, and record it as the hemispherical harmonic oscillator blank outline A0, and further construct the ball center trajectory A1 of the grinding wheel when it is tangent to the workpiece;

[0063] Step S2: Select trial cutting points based on the grinding wheel center trajectory A1;

[0064] Step S3: Mount the hemispherical resonator on the workpiece spindle, perform tool setting with the aid of a CCD camera, and calibrate the machine coordinate origin;

[0065] Step S4: Operate the machine tool to make the center of the ball-end grinding wheel approach each trial cutting point for trial cutting, record the coordinate values between the trial cutting point and the machine coordinate origin, and obtain the corrected trial cutting points; Based on the corrected trial cutting points, correct the grinding wheel center trajectory A1 to obtain the corrected grinding wheel center trajectory A2;

[0066] Step S5: Chamfer the grinding trajectory of the end face of the hemispherical resonator to obtain the ultra-precision grinding wheel center trajectory of the hemispherical resonator with chamfer, including the following steps:

[0067] Step S5-1: Offset the corrected grinding wheel center trajectory A2 by a distance of r in the direction of the workpiece entity interior to obtain the theoretical profile A3 before ultra-precision grinding of the hemispherical resonator; Offset the corrected grinding wheel center trajectory A2 by a distance of r + D in the direction of the workpiece entity interior to obtain the theoretical profile A4 after ultra-precision grinding of the hemispherical resonator, where D is the total grinding depth of the ultra-precision grinding of the hemispherical resonator;

[0068] Step S5-2: Chamfer the intersection points of the end face and the inner and outer spherical surfaces on the theoretical profile A4 after ultra-precision grinding of the hemispherical resonator, and denote the chamfer as C0 to obtain the theoretical profile A4 after ultra-precision grinding of the hemispherical resonator with chamfer;

[0069] Step S5-3: Use the CCD camera to observe the chamfer of the workpiece lip before grinding, measure the actual size of the chamfer of the hemispherical resonator blank lip according to the actual size represented by each pixel point in the image, and perform a 45° chamfer on the end face of the theoretical profile A3 before ultra-precision grinding of the hemispherical resonator, denoted as chamfer C1;

[0070] Step S5-4: Measure the vertical distance d between chamfer C0 and chamfer C1, and this distance d corresponds to the total grinding depth of the hemispherical resonator lip chamfer during ultra-precision grinding;

[0071] Step S5-5: Compare the size of d with the subsurface damage depth SSD of the hemispherical resonator blank. If d < SSD, grind the end face, and the cumulative grinding depth is AP. After grinding, offset the end face grinding trajectory in the grinding wheel center trajectory A2 by Ap into the entity interior;

[0072] Step S5-6: Repeat the operations of steps S5-1 to S5-5 until d ≥ SSD, and correct the obtained theoretical profile A4 after ultra-precision grinding of the hemispherical resonator with chamfer;

[0073] Step S5-7: Offset the corrected theoretical contour A4 of the chamfered hemispherical harmonic oscillator after ultra-precision grinding by a distance of r+D+a to the outside of the workpiece to obtain the grinding wheel center trajectory A5 of the chamfered hemispherical harmonic oscillator after ultra-precision grinding, where a is the tool setting error and the grinding allowance.

[0074] Step S5-8: If the shortest distance d between the chamfered region of the grinding wheel's center trajectory A5 and the chamfered region of the theoretical profile A3 of the hemispherical harmonic oscillator before ultra-precision grinding is... min ≤r+δ max δ max To determine the maximum runout of the ball-end grinding wheel, let a = a + 0.01 mm, and then repeat steps S5-7 to S5-8 until d... min >r+δ max If d min >r+δ max Then this step ends;

[0075] Step S6: Use ultra-precision grinding wheel A5 to process the hemispherical resonator with chamfered lip.

[0076] Specific implementation plan two: Step S1 includes the following steps:

[0077] Step S1-1: Establish the machine tool coordinate system, with the machine tool horizontal worktable parallel to the XOY plane, and the workpiece spindle perpendicular to the X-axis and parallel to the Y-axis;

[0078] Step S1-2: Mount the ball-end grinding wheel onto the grinding wheel spindle, set the grinding wheel spindle speed to 71000 r / min (under operating conditions), and use a laser displacement sensor to measure the maximum runout δ of the ball-end grinding wheel. max The maximum runout should be less than 5μm. If the runout exceeds 5μm, repeat this step to re-clamp.

[0079] Steps S1-3: Observe the position of the ball center of the ball end grinding wheel using a CCD camera and magnifying lens. Adjust the position of the ball center of the ball end grinding wheel by linear movement along the U-axis so that it is located on the rotation center line of the C-axis rotary table. Operate the machine tool to move the Z-axis so that the height of the ball center of the ball end grinding wheel is consistent with the height of the rotation axis of the grinding wheel spindle.

[0080] Step S1-4: Use a coordinate measuring machine to measure the dimensions of the hemispherical harmonic oscillator, and draw the cross-sectional outline through the axis of rotation in the drafting software, which is recorded as the hemispherical harmonic oscillator blank outline A0;

[0081] Step S1-5: Offset the contour line on one side of the rotation axis of the hemispherical harmonic oscillator blank by a distance r in the direction of the solid exterior, where r is the radius of the ball-end grinding wheel, which is 1.9 mm; obtain the trajectory A1 of the grinding wheel center when the grinding wheel is tangent to the workpiece. The rest of this implementation scheme is the same as in specific implementation scheme one.

[0082] Specific Implementation Scheme 3: The method for selecting the trial cutting points in step S2 is as follows: Select one point on each straight section of the grinding wheel's center trajectory A1 and on each circular arc section with a radius less than or equal to 2mm; select two points on each circular arc section with a radius greater than 2mm, ensuring that the length of the circular arc section between the two points is not less than half the length of the current circular arc section. All other aspects of this implementation scheme are the same as in Specific Implementation Scheme 2.

[0083] Specific implementation plan four: Step S3 includes the following steps:

[0084] Step S3-1: Mount the hemispherical resonator on the grinding wheel spindle and use a dial indicator to measure the radial runout of the workpiece at different positions, keeping the runout between 0 and 5 μm. If the runout exceeds 5 μm, repeat this step and re-clamp the workpiece.

[0085] Step S3-2: Use a CCD camera to perform tool setting. Based on the relative positions of the grinding wheel and the workpiece spindle in the machine tool coordinate system, operate the machine tool and move the X-axis so that the center of the ball end grinding wheel coincides with the rotation axis of the workpiece spindle; move the Y-axis so that the ball end grinding wheel just contacts the end face of the inner rod of the hemispherical harmonic oscillator.

[0086] Step S3-3: Operate the machine tool to move the grinding wheel center away from the workpiece by 3.1mm along the Y-axis. At this time, the distance between the grinding wheel center and the end face of the inner rod of the hemispherical harmonic oscillator is 5mm. Move the worktable 20mm along the negative X-axis and set the X-axis and Y-axis coordinates of this position as the origin of the machine tool coordinate system.

[0087] Step S3-4: Add the machine tool coordinate origin at the corresponding location in CAD, and measure the X and Y coordinate values ​​between each trial cutting point and the machine tool coordinate origin. This implementation scheme is otherwise the same as specific implementation scheme three.

[0088] Specific implementation plan five: Step S4 includes the following process:

[0089] Step S4-1: As Figure 5 As shown, the grinding trajectory of the hemispherical harmonic oscillator is divided into seven parts: inner rod, inner fillet, inner spherical surface, end face, outer spherical surface, outer fillet, and outer rod. The test cutting sequence is: inner spherical surface → inner rod → inner fillet → outer spherical surface → outer rod → outer fillet → end face.

[0090] Step S4-2: Operate the machine tool to bring the center of the ball end grinding wheel close to the test cutting point for test cutting. For the test cutting of the grinding paths of the inner fillet BC, inner spherical surface CD, and end face DE, move the horizontal worktable 5μm along the Y-axis to reduce the gap between the ball end grinding wheel and the workpiece surface. For the test cutting of the grinding paths of the inner rod AB, outer spherical surface EF, outer fillet FG, and outer rod GH, move the horizontal worktable 5μm along the X-axis to reduce the gap between the ball end grinding wheel and the workpiece surface.

[0091] Step S4-3: Manually rotate the ball head grinding wheel and the workpiece. If no grinding sound is produced, repeat step S4-2. If periodic grinding sound is produced, proceed directly to step S4-4.

[0092] Step S4-4: Record the X and Y coordinate values ​​between the current test cutting point and the machine tool coordinate origin, and input the coordinate values ​​of the current coordinate point into CAD to obtain the corrected test cutting point;

[0093] Step S4-5: Operate the machine tool, move the center of the ball of the ball-end grinding wheel to the next test cutting point, and repeat the operation of steps S4-2 to S4-4 until all test cutting points are corrected;

[0094] Step S4-6: Based on the corrected trial cutting points, correct the grinding wheel center trajectory A1 to obtain the corrected grinding wheel center trajectory A2. The rest of this implementation scheme is the same as specific implementation scheme four.

[0095] Specific Implementation Scheme Six: Steps S4-6 include the following process: For the grinding wheel sphere center trajectory A1, a straight line parallel to the rotation axis of the hemispherical harmonic oscillator is used to connect a corrected trial cutting point on the straight line machining trajectory, thus obtaining the corrected high-precision machining trajectory of the straight line trajectory segment; For the uncorrected arc trajectory with a radius greater than 2mm, a straight line is used to connect two corrected trial cutting points on the arc trajectory segment, and a perpendicular bisector of the line connecting the two points is drawn, so that the perpendicular bisector intersects the workpiece rotation axis at a point. With the intersection point as the center, an arc is drawn through the two corrected trial cutting points, thus obtaining the corrected high-precision machining trajectory of the arc trajectory segment; For the uncorrected arc trajectory with a radius less than 2mm, the straight line trajectory connecting the arc and the arc trajectory are tangent, and the arc trajectory passes through a corrected trial cutting point, thus obtaining the corrected high-precision machining trajectory of the arc trajectory segment.

[0096] By sequentially connecting each machining trajectory segment, the corrected grinding wheel center trajectory A2 is obtained. This implementation scheme is otherwise identical to specific implementation scheme five.

[0097] Specific Implementation Scheme Seven: The chamfer C0 size mentioned in step S5-2 is 15-30μm, and the chamfer size is the leg size of the isosceles right triangle corresponding to the hypotenuse of the chamfered side. All other aspects of this implementation scheme are the same as in Specific Implementation Scheme Six.

[0098] like Figure 10 As shown in (a) and (b), the end face lip of the hemispherical harmonic oscillator was successfully chamfered, and there was no chipping on the end face after machining. The chamfered lip area was free of defects, indicating that the subsurface damage of the chamfered lip of the hemispherical harmonic oscillator blank has been completely removed.

[0099] 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 reducing edge chipping on the end face of a hemispherical resonator through ultra-precision grinding, wherein the method is implemented using a hemispherical resonator grinding device, the device comprising three linear motion axes X, Y, and Z, a C-axis rotary table (1), two precision fine-tuning linear feed axes U-axis (12) and V-axis (3), a grinding wheel spindle (5), and a workpiece spindle (10); a horizontal worktable (7) is mounted on a two-dimensional moving platform, and the horizontal worktable (7) is controlled by a control system to move horizontally along the X and Y axes on the two-dimensional moving platform; the workpiece spindle (10) is provided with a workpiece spindle protective cover (8), and is mounted on the upper surface of the horizontal worktable (7) through the workpiece spindle protective cover (8), the axis of the workpiece spindle (10) being parallel to the Y-axis movement direction; the central axis of the C-axis rotary table (1) is parallel to the Z-axis, and its movement along the Z-axis direction is controlled by the control system. The height of the grinding wheel spindle (5) is changed; the grinding wheel spindle (5) is obliquely mounted below the U-axis (12) through the grinding wheel spindle fixing bracket (4), and the angle between the axis of the grinding wheel spindle (5) and the horizontal plane is 40°; the U-axis (12) is provided with a U-axis protective cover (11), and the U-axis (12) is rigidly connected to the C-axis turntable (1) through the U-axis connecting bracket (2). The V-axis (3) is installed below the C-axis turntable (1), and the lower end of the V-axis (3) is connected to the grinding wheel spindle fixing bracket (4). The grinding wheel spindle (5) is finely adjusted in the Y-axis direction and X-axis direction through the U-axis (12) and V-axis (3); during the grinding process of the hemispherical harmonic oscillator, the ball head grinding wheel (6) will move along the contour line of the workpiece (9). According to the different surface features of each segment of the workpiece (9), the grinding wheel rotation angle of each segment is changed to prevent the workpiece (9) from interfering with the ball head grinding wheel (6); characterized in that, The method includes the following steps: Step S1: Establish a machine tool coordinate system, clamp the ball-end grinding wheel onto the grinding wheel spindle, observe the center position of the ball-end grinding wheel through a CCD camera and a magnifying lens, measure the size of the hemispherical resonator, draw a cross-sectional contour line passing through the rotation axis in a drafting software, denoted as the rough blank contour A0 of the hemispherical resonator, and further construct the grinding wheel center trajectory A1 when the grinding wheel is tangent to the workpiece. Step S2: Select trial cutting points based on the grinding wheel center trajectory A1. Step S3: Clamp the hemispherical resonator onto the workpiece spindle, perform tool setting with the aid of a CCD camera, and calibrate the origin of the machine tool coordinate. Step S4: Operate the machine tool to make the center of the ball-end grinding wheel approach each trial cutting point for trial cutting, record the coordinate values between the trial cutting point and the origin of the machine tool coordinate to obtain the corrected trial cutting points; based on the corrected trial cutting points, correct the grinding wheel center trajectory A1 to obtain the corrected grinding wheel center trajectory A2. Step S5: Chamfer the grinding trajectory of the end face of the hemispherical resonator to obtain the ultra-precision grinding wheel center trajectory of the hemispherical resonator with chamfer, including the following steps: Step S5-1: Offset the corrected grinding wheel center trajectory A2 by a distance of r in the direction of the workpiece solid interior to obtain the theoretical contour A3 before ultra-precision grinding of the hemispherical resonator; offset the corrected grinding wheel center trajectory A2 by a distance of r + D in the direction of the workpiece solid interior to obtain the theoretical contour A4 after ultra-precision grinding of the hemispherical resonator, where D is the total grinding depth of the ultra-precision grinding of the hemispherical resonator. Step S5-2: On the theoretical contour A4 after ultra-precision grinding of the hemispherical resonator, chamfer the intersection points of the end face and the inner and outer spherical surfaces, denoted as chamfer C0, to obtain the theoretical contour A4 after ultra-precision grinding of the hemispherical resonator with chamfer. Step S5-3: Use a CCD camera to observe the chamfer of the workpiece lip before grinding, measure the actual size of the chamfer of the rough blank lip of the hemispherical resonator according to the actual size represented by each pixel point in the image, and perform a 45° chamfer on the end face of the theoretical contour A3 before ultra-precision grinding of the hemispherical resonator, denoted as chamfer C1. Step S5-4: Measure the vertical distance d between chamfer C0 and chamfer C1, and this distance d corresponds to the total grinding depth of the chamfer of the hemispherical resonator lip during ultra-precision grinding. Step S5-5: Compare the size of d and the subsurface damage depth SSD of the hemispherical resonator rough blank. If d < SSD, grind the end face, and the cumulative grinding depth is AP. After grinding, offset the end face grinding trajectory in the grinding wheel center trajectory A2 towards the solid interior by Ap. Step S5-6: Repeat the operations in steps S5-1 to S5-5 until d ≥ SSD to correct the obtained theoretical contour A4 after ultra-precision grinding of the hemispherical resonator with chamfer. Step S5-7: Offset the corrected theoretical contour A4 after ultra-precision grinding of the hemispherical resonator with chamfer by a distance of r + D + a in the direction of the workpiece solid exterior to obtain the ultra-precision grinding wheel center trajectory A5 of the hemispherical resonator with chamfer, where a is the tool setting error and the grinding allowance. Step S5-8: If the shortest distance d between the chamfered region of the grinding wheel's center trajectory A5 and the chamfered region of the theoretical profile A3 of the hemispherical harmonic oscillator before ultra-precision grinding is... min ≤r+δ max δ max To determine the maximum runout of the ball-end grinding wheel, let a = a + 0.01 mm, and then repeat steps S5-7 to S5-8 until d... min >r+δ max If d min >r+δ max Then this step ends; Step S6: The hemispherical resonator with chamfered edge is machined by ultra-precision grinding of the ball head grinding wheel along the ball center trajectory A5; Step S1 includes the following steps: Step S1-1: Establish the machine tool coordinate system, with the machine tool horizontal worktable parallel to the XOY plane, and the workpiece spindle perpendicular to the X-axis and parallel to the Y-axis; Step S1-2: Clamp the ball-end grinding wheel onto the grinding wheel spindle, set the grinding wheel spindle speed, and use a laser displacement sensor to measure the maximum runout δ of the ball-end grinding wheel. max The maximum runout should be less than 5μm. If the runout exceeds 5μm, repeat this step to re-clamp. Steps S1-3: Observe the position of the ball center of the ball end grinding wheel using a CCD camera and magnifying lens. Adjust the position of the ball center of the ball end grinding wheel by linear movement along the U-axis so that it is located on the rotation center line of the C-axis rotary table. Operate the machine tool to move the Z-axis so that the height of the ball center of the ball end grinding wheel is consistent with the height of the rotation axis of the grinding wheel spindle. Step S1-4: Use a coordinate measuring machine to measure the dimensions of the hemispherical harmonic oscillator, and draw the cross-sectional outline through the axis of rotation in the drafting software, which is recorded as the hemispherical harmonic oscillator blank outline A0; Step S1-5: Offset the contour line on one side of the rotation axis of the hemispherical harmonic oscillator blank by a distance r in the direction of the outside of the solid, where r is the radius of the ball head grinding wheel, to obtain the trajectory A1 of the grinding wheel center when the grinding wheel is tangent to the workpiece.

2. The ultra-precision grinding method for reducing edge chipping on the end face of a hemispherical harmonic oscillator according to claim 1, characterized in that, The method for selecting the trial cutting points in step S2 is as follows: select one point on each straight machining trajectory and the circular arc machining trajectory with a radius less than or equal to 2mm on each segment of the grinding wheel ball center trajectory A1; select two points on each circular arc machining trajectory with a radius greater than 2mm, and the length of the circular arc machining trajectory between the two points is not less than 1 / 2 of the length of the circular arc machining trajectory segment.

3. The ultra-precision grinding method for reducing edge chipping on the end face of a hemispherical harmonic oscillator according to claim 2, characterized in that, Step S3 includes the following steps: Step S3-1: Mount the hemispherical resonator on the workpiece spindle and use a dial indicator to measure the radial runout of the workpiece at different positions, keeping the runout between 0 and 5 μm. If the runout exceeds 5 μm, repeat this step and re-clamp the workpiece. Step S3-2: Use a CCD camera to perform tool setting. Based on the relative positions of the grinding wheel and the workpiece spindle in the machine tool coordinate system, operate the machine tool and move the X-axis so that the center of the ball end grinding wheel coincides with the rotation axis of the workpiece spindle; move the Y-axis so that the ball end grinding wheel just contacts the end face of the inner rod of the hemispherical harmonic oscillator. Step S3-3: Operate the machine tool to move the grinding wheel ball center away from the workpiece along the Y-axis, and move the worktable along the negative X-axis. Set the X-axis coordinate and Y-axis coordinate of this position as the origin of the machine tool coordinate system. Step S3-4: Measure the X and Y coordinate values ​​between each trial cutting point and the origin of the machine tool coordinate system.

4. The ultra-precision grinding method for reducing edge chipping on the end face of a hemispherical resonator according to claim 3, characterized in that, Step S4 includes the following process: Step S4-1: The grinding trajectory of the hemispherical harmonic oscillator is divided into 7 parts: inner rod, inner fillet, inner spherical surface, end face, outer spherical surface, outer fillet, and outer rod. The trial cutting sequence is: inner spherical surface → inner rod → inner fillet → outer spherical surface → outer rod → outer fillet → end face; Step S4-2: Operate the machine tool to bring the center of the ball end grinding wheel close to the test cutting point for a test cut; Step S4-3: Manually rotate the ball head grinding wheel and the workpiece. If no grinding sound is produced, repeat step S4-2. If periodic grinding sound is produced, proceed directly to step S4-4. Step S4-4: Record the X and Y coordinate values ​​between the current test cutting point and the machine tool coordinate origin; Step S4-5: Operate the machine tool, move the center of the ball of the ball-end grinding wheel to the next test cutting point, and repeat the operation of steps S4-2 to S4-4 until all test cutting points are corrected; Step S4-6: Based on the corrected trial cutting points, correct the grinding wheel ball center trajectory A1 to obtain the corrected grinding wheel ball center trajectory A2.

5. The ultra-precision grinding method for reducing edge chipping on the end face of a hemispherical resonator according to claim 4, characterized in that, The chamfer C0 dimension in step S5-2 is 15-30μm.

Images