A chemical mechanical polishing machine and a setting method for polishing a ball-end workpiece

Abstract

The present invention discloses a chemical mechanical polishing machine for polishing a ball-end workpiece and a setting method. The compound movement of the rotation movement and the swing movement of the polishing die module is adopted to provide all-round polishing for the surface of the ball-end workpiece to be polished. The best polishing effect can be obtained by setting the ratio of the rotation speed to the swing speed. The polishing die module is a structure for polishing ball-end workpieces with different diameter sizes. By applying a load to the ball-end workpiece, the torque data acquisition module collects the torque in the polishing process through a torque sensor in the form of a voltage signal to monitor the polishing process. By setting the ratio of the rotation speed to the swing speed, the finally obtained ratio of the rotation speed to the swing speed is applied to the polishing process, which can achieve uniform, accurate and efficient polishing of the ball-end workpiece, and the effect is better.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical lapping and polishing, and particularly to a chemical mechanical polishing machine for polishing ball-headed workpieces and a setting method thereof. Background Art

[0002] The concept of chemical mechanical polishing technology was first proposed by Monsanto in 1965. This technology was initially used to obtain high-quality glass surfaces and was later widely applied to the semiconductor industry. It was first used to polish single-crystal silicon wafers, and IBM successfully applied the CMP global planarization technology to the production of 64M DRAM in 1991. Since then, the CMP technology has developed rapidly and has become the main planarization technology in semiconductor manufacturing processes. Chemical mechanical polishing is a polishing method that combines chemical polishing and mechanical polishing, and the process quality after polishing depends on the balance degree of these two methods. Traditional chemical polishing can achieve global planarization, but the chemical polishing rate is slow. Traditional mechanical polishing has a high polishing rate, but it will leave scratches on the surface of the workpiece. By combining these two methods, softening the surface of the workpiece through chemical reactions and then mechanically removing it, a high removal rate can be obtained and global planarization of the workpiece can be achieved after polishing.

[0003] There are many influencing factors for chemical mechanical polishing, including the composition of the polishing liquid, the processing conditions during the polishing process, the selection of the polishing pad, and the initial state of the workpiece. Different polishing liquids will have different chemical reactions with the workpiece, affecting the formation speed of the soft layer, and thus affecting the material removal rate of the workpiece. The abrasive in the polishing liquid is mainly used for the mechanical removal of the soft layer, and different abrasives have a great impact on the surface quality of the polished workpiece. The processing conditions mainly include the polishing pressure and the relative movement form between the workpiece and the polishing pad. Selecting appropriate polishing pressure and movement form can improve the mechanical removal rate. The main function of the polishing pad is to bring the polishing liquid between the workpiece and the polishing pad. There are a large number of micropores on the surface of the polishing pad, and the shape of these micropores on the polishing pad will affect the contact area between the polishing pad and the workpiece and the formation of the liquid film between them. For different initial states of the workpiece, different processing technologies will be selected according to different workpiece surface states and shapes to finally obtain high surface quality.

[0004] Currently, for the lapping and polishing of ball-headed workpieces, there is only a rotary lapping and polishing structure. For ball-headed workpieces, the polishing process of this rotary lapping and polishing structure by self-rotation cannot perform all-round lapping and polishing for the ball head shape. Therefore, the polishing efficiency is low and the obtained polished surface quality is not high.

[0005] Therefore, there is an urgent need for a high-efficiency and high-quality lapping and polishing solution specifically for ball-headed workpieces. Summary of the Invention

[0006] In view of this, the present invention provides a chemical mechanical polishing machine and a setting method for polishing a ball-end workpiece, which can perform all-round polishing on the shape of the ball-end workpiece, with high polishing efficiency and high quality of the polished surface.

[0007] To achieve the above object, the technical solution of the present invention is: the polishing machine includes a polishing die module and a torque data acquisition module.

[0008] The polishing die module includes a polishing die, a rotating platform, a rotating motor, a swing rod, a slider, a ball screw, and a stepping motor; the polishing die is a ball socket die for polishing the ball-end workpiece, which has a spherical groove, and a ball socket polishing pad is arranged in the spherical groove; the polishing die is arranged on the rotating platform, and the rotating motor is arranged at the bottom of the rotating platform for controlling the rotating motion of the rotating platform; a swing rod perpendicular to the rotating platform is arranged below the rotating platform, and the lower part of the swing rod is connected to the slider through a ball head bearing; the ball screw makes a reciprocating motion under the control of the stepping motor, and the ball screw is connected to the slider through a connecting rod for pushing the slider to make a reciprocating motion, and the slider drives the swing rod to make a swinging motion;

[0009] The torque data acquisition module includes a torque sensor and a data acquisition card; the ball-end workpiece is fixed at one end of the torque sensor, and the ball-end workpiece does not rotate during the polishing process; the torque sensor is used to detect the friction torque between the ball-end workpiece and the ball socket polishing pad in real time during the polishing process; the data acquisition card acquires and outputs the friction torque detected by the torque sensor in real time.

[0010] Further, the ball socket polishing pad includes a set number of sector pads of the same size, and the sum of the central angles of all sector pads is 360°; the sector pads are arranged in the spherical groove and fit the inner wall of the spherical groove.

[0011] Further, the swing angle of the swinging motion is 60°.

[0012] Further, the ball-end workpiece is fixed at one end of the torque sensor by means of flange or screw fastening.

[0013] Further, the rotating motor controls the rotating speed range of the rotating platform to be 0 - 100 r / min, and the swinging speed of the swinging motion is 0 - 83 mm / s; the ratio of the rotating speed to the swinging speed is set as a fixed value.

[0014] Further, the number of sector pads is 12.

[0015] Further, the range of the torque sensor is 0 - 5 N·m, and the output sensitivity is 2.0 mV / V.

[0016] Further, the maximum sampling frequency of the data acquisition card is 10 kS / s, and the output frequency is 150 Hz.

[0017] Another embodiment of the present invention further provides a method for setting a chemical mechanical polishing machine for polishing a ball-end workpiece. For any of the above polishing machines, the following method is adopted for setting the ratio of the rotation speed to the swing speed:

[0018] The first step: Geometric calculation of the polishing trajectory points, which specifically includes the following steps:

[0019] S101. Taking the center of the ball socket mold as the origin O, a three-dimensional space fixed coordinate system OXYZ is established, where the horizontal plane is the XOY plane. The rotation platform swings around the center O of the ball socket mold at an angular velocity of w1 in the XOZ plane, and the set swing amplitude is ±30°; the rotation platform rotates around the Z axis at an angular velocity of w2.

[0020] S102. Taking the center of the ball socket mold as the origin O, a swing coordinate system OX1Y1Z1 in which the polishing mold swings reciprocally around the Y axis and a rotation coordinate system OX2Y2Z2 in which the polishing tool rotates around the Z axis are established.

[0021] S103. Arbitrarily take a point A2 on the polishing mold, and obtain the coordinates A1 of this point in the swing coordinate system OX1Y1Z1 through coordinate transformation, and then obtain the coordinates A of this point in the fixed coordinate system OXYZ through coordinate system transformation. The coordinates of point A are what is required, and the coordinates of A2 are (x2, y2, z2):

[0022]

[0023] Among them: R is the radius of the polishing mold; is the swing angle of the polishing mold around the Y axis, θ is the rotation angle of the polishing mold around the Z axis, -π / 2 ≤ θ ≤ π / 2.

[0024] S104. Taking the counterclockwise direction as positive and the clockwise direction as negative, the transformation matrix B from the rotation coordinate system OX2Y2Z2 to the swing coordinate system OX1Y1Z1 is:

[0025]

[0026] Among them, t is a time variable;

[0027] The transformation matrix C from the swing coordinate system OX1Y1Z1 to the fixed coordinate system OXYZ is:

[0028]

[0029] Among them, the substitution variable ψ is used to represent

[0030] During the polishing process, according to the coordinate transformation, the point A2 is transformed to A1 in the swing coordinate system:

[0031]

[0032] If the coordinates of A1 are (x1, y1, z1), then:

[0033]

[0034] Then the coordinate values in the oscillating coordinate system OX1Y1Z1 are:

[0035]

[0036] According to the coordinate transformation, point A1 is transformed to point A in the fixed coordinate system:

[0037]

[0038] If the coordinates of A are (x, y, z), then:

[0039]

[0040] Then the coordinate values of point A2 in the fixed coordinate system OXYZ are:

[0041]

[0042] Second step: Calculation of the wear amount of the ball socket mold, which specifically includes the following steps:

[0043] S201. Arbitrarily take a point P on the ball socket mold, with the initial coordinates (x0, y0, z0). According to the geometric relationship, the linear velocity provided by the rotational motion at point P is:

[0044] V2 = w2 × R × sinθ (10)

[0045] The linear velocity provided by the oscillating motion at point P is:

[0046]

[0047] The total linear velocity at point P is:

[0048]

[0049] The normal pressure received by point P during the polishing process is:

[0050]

[0051] Where F is the load applied to the ball head workpiece.

[0052] S202. According to the above analysis, the velocity and normal pressure of any point P on the ball socket mold during the polishing process can be obtained. Therefore, the instantaneous wear rate of point P can be obtained according to the Preston equation as follows:

[0053] MRR1 = K × F N × V (14)

[0054] where K is the Preston coefficient.

[0055] After time t, the wear amount at the microelement is:

[0056]

[0057] where Δs is the area of a single microelement.

[0058] Step 3: Selection of the ratio of the rotational speed to the swing speed of the optimal polishing mold, which specifically includes the following steps:

[0059] S301. For points on the same polishing mold, the values of the rotational speed and the swing speed directly determine the polishing trajectory. When the ratio of the rotational speed to the swing speed is i, set the value range of i, and select different values as i within the value range;

[0060] S302. Take the abrasion mark trajectory of a set point on the polishing mold, project the abrasion mark trajectory within 40 s onto the XOY plane to obtain the projection of the abrasion mark trajectory. Select a set y value on the XOY plane and draw a horizontal line. The current horizontal line and the projection of the abrasion mark trajectory together obtain n intersection points. The coordinate of the jth intersection point is x j , where j is the intersection point serial number, and the difference between the coordinates at adjacent intersection points is Δu j That is:

[0061] Δu j = x j+1 - x j (16)

[0062] The average value of all differences Δu1 to Δu n is and the variance is D(Δu)

[0063] For all values of i within the value range, calculate the variances of the corresponding intersection point differences respectively, and take the value of i corresponding to the minimum variance as the optimal ratio of the rotational speed to the swing speed.

[0064] Beneficial effects:

[0065] 1. An embodiment of the present invention provides a chemical mechanical polishing machine for polishing ball - headed workpieces. The compound motion of the rotation and swing of the polishing die module provides all - round polishing for the surface of the ball - headed workpiece to be polished. The best polishing effect can be obtained by setting the ratio of the rotation speed to the swing speed. The polishing die module is a structure for polishing ball - headed workpieces with different diameter sizes. By applying load to the ball - headed workpiece, the torque data acquisition module collects the torque in the polishing process through a torque sensor in the form of a voltage signal to monitor the polishing process. Therefore, this polishing machine has high polishing efficiency and can obtain a polished surface with high quality.

[0066] 2. In the chemical mechanical polishing machine for polishing ball - headed workpieces provided by the embodiment of the present invention, the ball socket polishing pad in the ball socket die is designed as a sector pad, and a "petal - type" die structure is composed of a plurality of sector pads, so that the polishing pad can cover the die as much as possible and improve the polishing rate.

[0067] 3. The embodiment of the present invention also provides a method for determining the ratio of the rotation speed to the swing speed of a chemical mechanical polishing machine for polishing ball - headed workpieces. This method analyzes the wear track of the polishing die, and uses the less overlap and more uniform distribution of the wear track as an index to evaluate the surface quality, determines the ratio within a certain range, and finally applies the obtained ratio of the rotation speed to the swing speed to the polishing process, which can achieve uniform, accurate and efficient polishing of the ball - headed workpiece, and has a better effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 is a schematic structural diagram of the chemical mechanical polishing machine for polishing ball - headed workpieces provided by the embodiment of the present invention;

[0069] Figure 2 is a schematic structural diagram of the ball socket die in the embodiment of the present invention;

[0070] Figure 3 is a schematic diagram of the coordinate system constructed in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] The following examples are given in conjunction with the drawings to describe the present invention in detail.

[0072] Refer to Figure 1 , the present invention provides a chemical mechanical polishing machine for polishing ball - headed workpieces, which includes a polishing die module and a torque data acquisition module.

[0073] The polishing die module includes a polishing die, a rotation platform, a rotation motor, a swing rod, a slider, a ball screw and a stepping motor.

[0074] The lapping and polishing die is a spherical socket die for polishing ball-headed workpieces. It has a spherical groove, and a spherical socket polishing pad is arranged in the spherical groove. In the embodiment of the present invention, a petal-shaped die structure is given, that is, the spherical socket polishing pad includes a set number of sector pads of the same size, and the sum of the central angles of all the sector pads is 360°; the sector pads are arranged in the spherical groove and fit the inner wall of the spherical groove to form a petal shape. The "petal-shaped" die structure enables the polishing pad to cover the die as much as possible, improving the polishing rate. The structural schematic diagram of the lapping and polishing die module is as shown in Figure 2 shown, and the number of sector pads is 12. Since the polishing liquid has a certain corrosiveness, the parts materials used for the die module need to be selected as acid and alkali resistant materials. During the process of polishing the ball-headed workpiece, the compound motion will cause the polishing liquid to spill out, so a cover plate is added to the spherical socket die to prevent the spillage of the polishing liquid.

[0075] The lapping and polishing die is arranged on a rotating platform, and a rotating motor is arranged at the bottom of the rotating platform to control the rotation motion of the rotating platform. In the embodiment of the present invention, according to the actual polishing effect on the ball-headed workpiece, the rotation speed range of the rotating platform is controlled to be 0 - 100 r / min.

[0076] A swing rod perpendicular to the rotating platform is arranged below the rotating platform. The lower part of the swing rod is connected to a slider through a ball head bearing; the ball screw makes a reciprocating motion under the control of a stepping motor. The ball screw is connected to the slider through a connecting rod to push the slider to make a reciprocating motion, and the slider drives the swing rod to make a swinging motion; in the embodiment of the present invention, according to the actual polishing effect on the ball-headed workpiece, the swing angle of the swinging motion is controlled to be 60°, and the swing speed of the swinging motion is controlled to be 0 - 83 mm / s. During the polishing process of the ball-headed workpiece, the ratio of the rotation speed to the swing speed is set to a fixed value according to the polishing effect, so as to obtain better polishing quality.

[0077] The torque data acquisition module includes a torque sensor and a data acquisition card. The torque sensor is used to detect the friction torque between the ball-headed workpiece and the spherical socket polishing pad in real time during the polishing process. In the embodiment of the present invention, the range of the torque sensor is 0 - 5 N·m, and the output sensitivity is 2.0 mV / V. In the embodiment of the present invention, the data acquisition card acquires and outputs the friction torque detected by the torque sensor in real time. Specifically, in the embodiment of the present invention, an NI6008 data acquisition card is used. This data acquisition card has a total of 12 digital input ports and 8 analog input ports. The maximum sampling frequency of the data acquisition card is 10 kS / s, and the output frequency is 150 Hz.

[0078] The ball-end workpiece is fixed at one end of the torque sensor, and the ball-end workpiece does not rotate during the lapping and polishing process; the present invention uses a workpiece loading structure to fix the ball-end workpiece at one end of the torque sensor by means of flange or screw fastening, connects a self-designed tap chuck to the tapping and drilling integrated machine, connects the torque sensor and the tap chuck to each other through a flange, and connects the ball-end workpiece through a flange clamping member or a flange connecting member.

[0079] The embodiment of the present invention also provides a method for setting a chemical mechanical polishing machine for polishing a ball-end workpiece. Using the polishing machine described in any of the above embodiments, the following method is used to set the ratio of the rotation speed to the swing speed therein:

[0080] The first step: geometric calculation of the polishing trajectory points, specifically including the following steps

[0081] S101. Taking the center of the ball socket mold as the origin O, a three-dimensional space fixed coordinate system OXYZ is established, where the horizontal plane is the XOY plane. The rotation platform swings around the center O of the ball socket mold at an angular velocity of w1 in the XOZ plane, and the set swing amplitude is ±30°; the rotation platform rotates around the Z axis at an angular velocity of w2.

[0082] S102. Taking the center of the ball socket mold as the origin O, a swing coordinate system OX1Y1Z1 in which the polishing mold swings reciprocally around the Y axis and a rotation coordinate system OX2Y2Z2 in which the polishing tool rotates around the Z axis are established. As Figure 3 shown, both the swing coordinate system OX1Y1Z1 and the rotation coordinate system OX2Y2Z2 are moving coordinate systems. The swing coordinate system OX1Y1Z1 can be regarded as formed by the fixed coordinate system OXYZ with the swing movement, and at the same time, the rotation coordinate system OX2Y2Z2 can be regarded as formed by the fixed coordinate system OXYZ with the rotation movement.

[0083] S103. Arbitrarily take a point A2 on the polishing mold, obtain the coordinate A1 of this point in the swing coordinate system OX1Y1Z1 through coordinate transformation, and then obtain the coordinate A of this point in the fixed coordinate system OXYZ through coordinate system transformation. The coordinate of point A is the required one, and the coordinate of A2 is (x2, y2, z2):

[0084]

[0085] where: R is the radius of the polishing mold; is the swing angle of the polishing mold around the Y axis, θ is the rotation angle of the polishing mold around the Z axis, -π / 2 ≤ θ ≤ π / 2.

[0086] S104. Taking the counterclockwise direction as positive and the clockwise direction as negative, the transformation matrix B from the rotation coordinate system OX2Y2Z2 to the swing coordinate system OX1Y1Z1 is:

[0087]

[0088] where t is the time variable.

[0089] The transformation matrix from the oscillating coordinate system OX1Y1Z1 to the fixed coordinate system OXYZ is C:

[0090]

[0091] where the substitution variable ψ is used to represent

[0092] During the polishing process, according to the coordinate transformation, point A2 is transformed to A1 in the oscillating coordinate system:

[0093]

[0094] If the coordinates of A1 are (x1, y1, z1), then:

[0095]

[0096] Then the coordinate values in the oscillating coordinate system OX1Y1Z1 are:

[0097]

[0098] According to the coordinate transformation, point A1 is transformed to A in the fixed coordinate system:

[0099]

[0100] If the coordinates of A are (x, y, z), then:

[0101]

[0102] Then the coordinate values of point A2 in the fixed coordinate system OXYZ are:

[0103]

[0104] Step 2: Calculation of the wear amount of the ball socket mold, which specifically includes the following steps:

[0105] S201. Arbitrarily select a point P on the ball socket mold, with the initial coordinates (x0, y0, z0). According to the geometric relationship, the linear velocity provided by the rotational motion at point P is:

[0106] V2 = w2 × R × sinθ (10)

[0107] The linear velocity provided by the oscillating motion at point P is:

[0108]

[0109] The bus speed at point P is:

[0110]

[0111] The normal pressure on point P during the polishing process is:

[0112]

[0113] where F is the load applied to the ball-end workpiece;

[0114] S202. According to the above analysis, the speed and normal pressure of any point P on the spherical socket mold during the polishing process can be obtained. Therefore, the instantaneous wear rate of point P can be obtained according to the Preston equation as:

[0115] MRR1 = K × F N × V (14)

[0116] where K is the Preston coefficient;

[0117] After time t, the wear amount at the microelement is:

[0118]

[0119] where Δs is the area of a single microelement;

[0120] Step 3: Selection of the ratio of the rotation speed to the swing speed of the optimal lapping and polishing mold, which specifically includes the following steps:

[0121] S301. For points on the same lapping and polishing mold, the values of the rotation speed and the swing speed directly determine the polishing trajectory. When the ratio of the rotation speed to the swing speed is i, set the value range of i, and select different values as i within the value range;

[0122] S302. Take the scratch track of a set point on the lapping and polishing mold, project the scratch track within 40 s to the XOY plane to obtain the projected scratch track. Select a set y value on the XOY plane and draw a horizontal line. The current horizontal line and the projected scratch track together obtain n intersection points. The coordinate of the jth intersection point is x j , j is the intersection point serial number, and the difference between the coordinates at adjacent intersection points is Δu j That is:

[0123] Δu j = x j+1 - x j (16)

[0124] The average value of all differences Δu1 to Δu n is The variance is D(Δu). According to the mean and variance calculation formulas, it can be obtained that:

[0125]

[0126]

[0127] For all values of i within the value range, calculate the variances of the corresponding intersection differences respectively, and use the value of i corresponding to the minimum variance as the optimal rotation speed and swing speed ratio.

[0128] Now select a certain y value, scan the rotation speed and swing speed ratio i of the tool, the scanning range is 31 - 40, the scanning interval is 1, and extract the x coordinate values of this point in the Matlab simulation wear track respectively. Substitute them into formulas (15), (16) and (17) to calculate the variances under different i values. Compare the obtained variances. The smaller the variance, the less the wear tracks overlap and the more evenly the wear tracks are distributed, and better surface quality can be obtained.

[0129] In summary, the above is only a preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for setting a chemical mechanical polishing machine for polishing a ball-end workpiece, characterized in that, A chemical mechanical polishing machine for polishing a ball-end workpiece is adopted. The polishing machine includes a polishing die module and a torque data acquisition module; The polishing die module includes a polishing die, a self-rotating platform, a self-rotating motor, a swing rod, a slider, a ball screw, and a stepping motor; the polishing die is a ball socket die for polishing a ball-end workpiece, which has a spherical groove, and a ball socket polishing pad is arranged in the spherical groove; the polishing die is arranged on the self-rotating platform, and the self-rotating motor is arranged at the bottom of the self-rotating platform for controlling the self-rotating motion of the self-rotating platform; a swing rod perpendicular to the self-rotating platform is arranged below the self-rotating platform, and the lower part of the swing rod is connected to the slider through a ball head bearing; the ball screw makes a reciprocating motion under the control of the stepping motor, and the ball screw is connected to the slider through a connecting rod for pushing the slider to make a reciprocating motion, and the slider drives the swing rod to make a swinging motion; The torque data acquisition module includes a torque sensor and a data acquisition card; the ball-end workpiece is fixed at one end of the torque sensor, and the ball-end workpiece does not rotate during the polishing process; The torque sensor is used to detect the friction torque between the ball-end workpiece and the ball socket polishing pad in real time during the polishing process; the data acquisition card collects and outputs the friction torque detected by the torque sensor in real time; The following method is adopted for setting the ratio of the self-rotating speed and the swinging speed of the polishing die: The first step: Geometric calculation of the polishing trajectory points, which specifically includes the following steps S101. Taking the center of the ball of the ball socket die as the origin O, a three-dimensional space fixed coordinate system OXYZ is established, where the horizontal plane is the XOY plane. The self-rotating platform swings around the center of the ball O of the ball socket die at an angular velocity of w1 in the XOZ plane, and the set swing amplitude is ±30°; the self-rotating platform rotates around the Z axis at an angular velocity of w2. S102. Taking the center of the ball of the ball socket die as the origin O, a swinging coordinate system OX1Y1Z1 in which the polishing die makes a reciprocating swing around the Y axis and a rotating coordinate system OX2Y2Z2 in which the polishing tool makes a self-rotating motion around the Z axis are established; S103. Arbitrarily take a point A2 on the polishing die, and obtain the coordinates A1 of this point in the swinging coordinate system OX1Y1Z1 through coordinate transformation, and then obtain the coordinates A of this point in the fixed coordinate system OXYZ through coordinate system transformation. The point A2 is the required one, and the coordinates of A2 are (x2, y2, z2): Where: R is the radius of the lapping die; is the swing angle of the lapping die around the Y-axis, and θ is the rotation angle of the lapping die around the Z-axis, -π / 2 ≤ θ ≤ π / 2; S104. Taking the counterclockwise direction as positive and the clockwise direction as negative, the transformation matrix from the rotating coordinate system OX2Y2Z2 to the swinging coordinate system OX1Y1Z1 is B: Where t is a time variable; The transformation matrix from the swinging coordinate system OX1Y1Z1 to the fixed coordinate system OXYZ is C: where the reference variable ψ is used to refer to During the polishing process, according to the coordinate transformation, the point A2 is transformed into A1 in the swinging coordinate system: Where the coordinates of A1 are (x1, y1, z1), then: Then the coordinate values in the swinging coordinate system OX1Y1Z1 are: According to the coordinate transformation, the point A1 is transformed into A in the fixed coordinate system: The coordinates of A are (x, y, z), then: Then the coordinate values of the point A2 in the fixed coordinate system OXYZ are: Thus, the grinding mark trajectory of a set point on the polishing die is determined; Step 2: Calculation of the wear amount of the ball socket mold, which specifically includes the following steps: S201. Arbitrarily select a point P on the ball socket mold with the initial coordinates (x0, y0, z0). According to the geometric relationship, the linear velocity provided by the rotational motion at point P is: V2 = w2 × R × sinθ (10) The linear velocity provided by the oscillating motion at point P is: The total linear velocity at point P is: The normal pressure received by point P during the polishing process is: where F is the load applied to the ball head workpiece; S202. Based on the above analysis, the magnitudes of the velocity and normal pressure of any point P on the ball socket mold during the polishing process can be obtained. Therefore, according to the Preston equation, the instantaneous wear rate of point P is: MRR1 = K × F N × V (14) where K is the Preston coefficient; After a time t, the wear amount at the microelement is: where Δs is the area of a single microelement; Step 3: Selection of the ratio of the rotational speed to the oscillating speed of the optimal polishing mold, which specifically includes the following steps: S301. For points on the same polishing mold, the values of the rotational speed and the oscillating speed directly determine the polishing trajectory. When the ratio of the rotational speed to the oscillating speed is i, set the value range of i, and select different values as i within the value range; S302. Take the grinding mark trajectory of a set point on the grinding and polishing die, project the grinding mark trajectory within 40 s onto the XOY plane to obtain the projected grinding mark trajectory. Select a set y value on the XOY plane and draw a horizontal line. The current horizontal line and the projected grinding mark trajectory together yield n intersection points. The coordinate of the j-th intersection point is x j , where j is the intersection point serial number, and the difference between the coordinates at adjacent intersection points is Δu j That is: Δu j = x j+1 - x j (16) All differences Δu1~Δu n The average value is and the variance is D(Δu); For all values of i within the value range, calculate the variances of the corresponding intersection differences respectively, and use the value of i corresponding to the minimum variance as the optimal ratio of the rotational speed to the oscillating speed.

2. The lapping and polishing machine setting method according to claim 1, characterized in that The ball socket polishing pad includes a set number of sector pads of the same size, and the sum of the central angles of all sector pads is 360°; the sector pads are arranged inside the spherical groove and fit the inner wall of the spherical groove.

3. The lapping machine setting method according to claim 1, characterized in that, The oscillating angle of the oscillating motion is 60°.

4. The lapping and polishing machine setting method according to claim 1, characterized in that The ball head workpiece is fixed to one end of the torque sensor by means of flange or screw fastening.

5. The lapping machine setting method according to claim 1, wherein The rotational motor controls the rotational speed range of the rotational platform to be 0 - 100 r / min, and the oscillating speed of the oscillating motion is 0 - 83 mm / s; the ratio of the rotational speed to the oscillating speed is set as a fixed value.

6. The lapping and polishing machine setting method according to claim 2, characterized in that, The number of the sector pads is 12.

7. The lapping machine setting method according to claim 2, characterized in that, The range of the torque sensor is 0 - 5 N·m, and the output sensitivity is 2.0 mV / V.

8. The lapping machine setting method according to claim 1, wherein, The maximum sampling frequency of the data acquisition card is 10 kS / s, and the output frequency is 150 Hz.

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