Polishing equipment

Abstract

The invention provides polishing equipment which comprises a machine body, a first main shaft, a second main shaft and a swing shaft, and a movement mechanism is arranged on the machine body; the movement mechanism is used for driving the first spindle to rotate around the axis; polishing heads are arranged at the lower ends of the first spindles; a clamping head is arranged at the upper end of the second spindle. The movement mechanism is further used for driving the second spindle to rotate. The swing shaft is perpendicular to the first spindle and the second spindle, the second spindle is in transmission connection with the swing shaft, and the movement mechanism is further used for driving the second spindle to swing in the vertical plane through the swing shaft. Wherein the first main shaft and the second main shaft are coaxial in the vertical direction, the axis of the first main shaft and the axis of the second main shaft intersect with the axis of the swing shaft at a virtual point, and the virtual point coincides with the virtual sphere center of the clamping head. The swing arm is connected to the moving table through a swing shaft and a speed reducer and driven by a swing motor. According to the scheme, the uniformity of the movement track of the polishing head on the surface of the curved-surface workpiece can be guaranteed, the surface quality is improved, and the machining precision is improved.

Description

Technical Field

[0001] This application relates to the field of surface processing technology, and particularly to a polishing device. Background Art

[0002] In the related art, during grinding and polishing, the contact forces in the contact area between the processing head and the workpiece are different. Therefore, it is difficult to ensure the uniformity of the movement trajectory of the abrasive grains on the surface of the spherical cover, and it is difficult to ensure the surface roughness and roundness during the processing of the spherical cover. Summary of the Invention

[0003] To solve the problems existing in the related art, this application provides a polishing device that can ensure the uniformity of the movement trajectory of the polishing head on the surface of the curved workpiece, improve the surface quality, and enhance the processing accuracy.

[0004] In the first aspect of this application, a polishing device is provided, including:

[0005] A machine body, on which a motion mechanism is provided;

[0006] A first main shaft and a second main shaft. The motion mechanism is used to drive the first main shaft to rotate around the axis of the main shaft; a polishing head is provided at the lower end of the first main shaft; a clamping head is provided at the upper end of the second main shaft, and the clamping head is used to mount a workpiece with a spherical surface. The motion mechanism is also used to drive the second main shaft to rotate self - sufficiently;

[0007] A swing shaft, which is perpendicular to the first and second main shafts. The second main shaft is in transmission connection with the swing shaft, and the motion mechanism is also used to drive the second main shaft to swing in the vertical plane through the swing shaft;

[0008] Wherein, the first main shaft and the second main shaft are co - axial in the vertical direction, and the axes of the first main shaft and the second main shaft intersect at a virtual point with the axis of the swing shaft. The virtual point coincides with the virtual spherical center of the clamping head.

[0009] In one implementation, the machine body includes a machine table and a frame installed on the machine table;

[0010] The motion mechanism includes:

[0011] A first driving mechanism and a second driving mechanism. The first driving mechanism is installed on the frame, and the first driving mechanism is used to move along a first horizontal direction; the second driving mechanism is installed on the first driving mechanism, and the second driving mechanism is used to move along the vertical direction. The first main shaft is installed on the second driving mechanism,

[0012] A third driving mechanism, installed on the machine table, and the third driving mechanism is used to move along a second horizontal direction. The first horizontal direction and the second horizontal direction are perpendicular;

[0013] A turntable assembly, the turntable assembly is provided with a fourth driving mechanism, and the fourth driving mechanism is used to drive the second main shaft to rotate self - rotatably;

[0014] A fifth driving mechanism is installed on the third driving mechanism, the turntable is installed on the fifth driving mechanism, the fifth driving mechanism is provided with the swing shaft, the axial direction of the swing shaft is along the second horizontal direction, and the fifth driving mechanism is used to drive the turntable to swing.

[0015] In one embodiment, a first position detection device is provided on the first driving mechanism, the position detection device is provided with a detection head, the detection head is used to align with the edge of the workpiece, and is used to detect the lateral position of the workpiece through the displacement deviation of the edge after the workpiece rotates one week;

[0016] A second position detection device is provided on the machine table and is located on the axial direction of the swing shaft. The second position detection device is used to acquire the longitudinal profile image of the workpiece and detect the position of the workpiece relative to the axis of the swing shaft based on the longitudinal profile image.

[0017] In one embodiment, the fifth driving mechanism includes a fifth motor, a speed reducer connected to the fifth motor, and the swing shaft connected to the speed reducer; a swing arm is provided at the output end of the swing shaft, and the swing arm is perpendicular to the swing shaft; a laterally extending mounting table is provided at one end of the swing arm away from the swing shaft, the turntable is installed on the mounting table and is located on the side of the mounting table close to the swing arm, and the axis of the second main shaft is perpendicular to the extending direction of the mounting table.

[0018] In one embodiment, the first position detection device includes a laser displacement meter, the laser beam emitted by the laser displacement meter is along the vertical direction, and the laser beam is parallel to the longitudinal center line of the clamping head, and there is a set distance between the laser beam and the longitudinal center line of the clamping head;

[0019] The second position detection device includes an image collector, the image collector is connected to a processor, and the processor is used to determine the virtual center of the sphere of the workpiece according to the image collected by the image collector and judge whether the virtual center of the sphere is located at a preset coordinate origin, and the coordinate origin is located at the axis of the swing shaft.

[0020] In one embodiment, the second main shaft includes a clamping head, the clamping head is provided with an adsorption surface, the adsorption surface adsorbs the workpiece through vacuum, and the clamping head includes a non - adsorption surface for supporting the workpiece and an adsorption surface that is the same arc surface as the non - adsorption surface, and the area of the adsorption surface is 1 / 4 of the non - adsorption area;

[0021] A vacuum channel is provided inside the second main shaft. The vacuum channel spirally surrounds the inner hole of the second main shaft along the axis of the second main shaft, and the end of the vacuum channel is connected to a pneumatic rotary joint.

[0022] The clamping head is coaxially installed at the top flange of the second main shaft through stop positioning. The clamping head is provided with an annular adsorption groove, and the annular adsorption grooves are radially and equidistantly distributed on the clamping head.

[0023] In one embodiment, the polishing head is cup-shaped, and the polishing head satisfies:

[0024] The polishing head base is nested in the flange of the first main shaft through conical surface fitting, and the inner cavity polishing surface of the polishing head is coaxially arranged with the axis of the first main shaft.

[0025] 6-8 polishing liquid diversion grooves are equidistantly opened along the circumferential direction on the chamfered end surface of the polishing head, and the groove depth is 1 / 4-1 / 2 of the thickness of the polishing wheel.

[0026] A ring-shaped flange is provided on the outer diameter side wall of the polishing head, and a weight balance block is fixed on the upper surface of the flange.

[0027] In one embodiment, an error compensation system is further included. The error compensation system includes:

[0028] The laser interferometer mirror group is installed on the reference planes on both sides of the bed through a magnetic base, forming a 45° optical path with each axis measurement mirror group; the error compensation table data is uploaded to the control system through the interface, and the compensation instruction preferentially executes the flatness compensation of the X / Y axis plane; the scraping compensation amount of the guide rail is distributed along the length direction of the guide rail according to the formula Δ = 0.8L + 1.2 (μm), and the scraping depth gradient decreases.

[0029] In one embodiment, the laser displacement meter is eccentrically installed on the right side surface of the Z-axis slide plate through an adjustable bracket, and the laser emission direction of the laser displacement meter forms an angle of 55°-60° with the axis of the polishing head.

[0030] The laser displacement meter includes three groups of laser probes distributed at an equal angle of 120°, and is connected to the Z-axis detection bracket through a ball joint; the parallelism between the measurement reference plane and the X-Y plane of the machine tool coordinate system is adjusted to

[0031] ≤0.005mm; the reflection signal receivers are annularly distributed around the laser emitter through optical fiber bundles to form a coaxial detection optical path.

[0032] In one embodiment, the clamping head includes:

[0033] The base body is provided with positioning pin holes at the bottom, and the positioning pin holes and the positioning pins of the first main shaft flange form an H7 / g6 transition fit; the perpendicularity between the measuring surface of the reference ring and the axis of the first main shaft is finely adjusted by three circumferentially evenly distributed adjusting jackscrews;

[0034] The silica gel protection pad is clamped on the surface of the base body through a dovetail groove, and its edge is provided with an anti-overflow flanging with a thickness of 0.5 mm.

[0035] The technical solution provided by this application may include the following beneficial effects:

[0036] In the solution of this application, during the processing, the intersection point of the rotation axis of the second main shaft, the rotation axis of the first main shaft and the swing axis of the turntable in space coincides at one point, and this coincidence point is the center of the spherical cover. In this way, it can ensure that the contact force in the contact area between the processing head and the workpiece is consistent during the grinding and polishing processes, ensure the uniformity of the movement trajectory of the polishing head on the surface of the curved workpiece, improve the surface quality, and improve the processing accuracy.

[0037] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this application. Brief Description of the Drawings

[0038] By describing the exemplary embodiments of this application in more detail in conjunction with the drawings, the above and other objects, features and advantages of this application will become more obvious. Among them, in the exemplary embodiments of this application, the same reference numerals generally represent the same components.

[0039] Figure 1 is a schematic structural diagram of the polishing equipment shown in the embodiment of this application;

[0040] Figure 2 is a schematic structural diagram of another perspective of the polishing equipment shown in the embodiment of this application;

[0041] Figure 3 is a schematic structural diagram of the control system of the polishing equipment shown in the embodiment of this application;

[0042] Figure 4 is a schematic structural diagram of the second main shaft of the polishing equipment shown in the embodiment of this application.

[0043] Reference Numerals:

[0044] 1. Gantry column; 2. X-axis servo motor; 3. X-axis lead screw; 4. X-axis linear guide; 5. First spindle; 6. First spindle seat; 7. Z-axis carriage; 8. Z-axis lead screw; 9. Torque sensor; 10. Polishing head; 11. Ball cover; 12. Turntable; 13. Polishing liquid nozzle bracket; 14. Turntable housing; 15. Y-axis linear guide; 16. Y-axis lead screw; 17. Machine body; 18. Bed foot; 19. Swing arm; 20. Y-axis moving table; 21. Center distance adjustment motor; 22. Laser displacement gauge; 23. Z-axis linear guide; 24. Z-axis linear guide slider; 25. Y-axis moving table carriage; 26. Rear support of X-axis lead screw; 27. Cover plate of rear support of X-axis lead screw; 28. Z-axis linear guide; 29. X-axis proximity switch; 30. Z-axis servo motor; 31. Coupling; 32. X-axis linear guide slider; 33. X-axis nut seat; 34. Z-axis moving table carriage; 35. Swing axis; 36. Reducer; 37. Swing motor; 38. Y-axis linear guide slider; 39. Y-axis servo motor; 40. Pneumatic rotary joint; 41. Cover plate of turntable flange; 42. Rotor; 43. Stator; 44. Second spindle; 441. Rotor; 442. Stator; 45. Connecting shaft; 451. Angular contact bearing; 46. Clamping head; 461. Sealing ring; 462. Dust-proof ring; 47. Polishing liquid nozzle bracket; 48. Polishing liquid nozzle. Detailed implementation manners

[0045] The preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present application will be more thorough and complete, and can fully convey the scope of the present application to those skilled in the art.

[0046] The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "the" and "said" used in the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0047] The technical solutions of the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0048] See Figures 1-4The present application provides a polishing device, including a body 18, a first spindle 5, a second spindle 44 and a swing shaft 35, wherein a motion mechanism is provided on the body 18; the motion mechanism is used to drive the first spindle 5 to rotate around its axis; a polishing head 10 is provided at the lower end of the first spindle 5; a chuck 46 is provided at the upper end of the second spindle 44, the chuck 46 is used to mount a workpiece 11 having a spherical surface, the workpiece 11 is a workpiece having a spherical surface, and the motion mechanism is also used to drive the second spindle 44 to rotate; the swing shaft 35 is perpendicular to the first spindle 5 and the second spindle 44, the second spindle 44 is connected to the swing shaft 35 by transmission, and the motion mechanism is also used to drive the second spindle 44 to swing in a vertical plane through the swing shaft 35; wherein the first spindle 5 and the second spindle 44 are coaxial in the vertical direction, the axes of the first spindle 5 and the second spindle 44 intersect with the axis of the swing shaft 35 at a virtual point, and the virtual point coincides with the virtual sphere center of the chuck 46. The swing arm 19 is connected to the moving platform 20 via a swing shaft 35 and a speed reducer 36 , and is driven by a swing motor 37 .

[0049] In the solution of the present application, the workpiece 11 has a curved surface, such as a ball cover. When processing the inner and outer surfaces of the ball cover, the ball cover is fixed on the clamping head 46 of the second spindle 44, and the turntable 12 drives the first spindle 5 to rotate in the clockwise direction. At the same time, the turntable 12 drives the ball cover to make reciprocating swinging motion around the center of the ball through the swing arm 19. The polishing head 10 is driven by the first spindle 5 to rotate in the counterclockwise direction and the polishing head is controlled by the second driving mechanism to move up and down to adjust the polishing force. These three movements and the feed movement cooperate with each other to achieve polishing of the inner and outer surfaces of the ball cover.

[0050] In the present application, the shape of the polishing head 10 is an inverted cup shape, and the opening edge of the cup-shaped polishing head 10 is a polishing surface with abrasive particles. The polishing is achieved by the envelope generated by the unfolding movement of the polishing head 10 on the surface of the spherical cover. Since the cross-section of the virtual sphere of the workpiece 11 at any point is a plane circle, the plane circle of any cross-section can intersect with the surface of the sphere, and the circumference of the plane circle is equal to the circumference of the intersection line. When polishing the spherical surface of the workpiece 11, the axis of the polishing head 10 intersects with the axis of the spherical surface at a certain angle and swings back and forth. The trajectory formed by the rotation of the spherical surface and the polishing head is a spherical surface, which ensures the uniformity of the movement trajectory of the polishing surface of the polishing head on the surface of the spherical cover and the consistency of pressure.

[0051] In the related art, during grinding and polishing processes, the contact forces in the contact area between the processing head and the workpiece are different. Therefore, it is difficult to ensure the uniformity of the movement trajectories of abrasive grains on the surface of the spherical cover, and it is difficult to ensure the surface roughness and roundness during the processing of the spherical cover. In the solution of the present application, during the processing, the intersection point of the rotation axis of the second spindle 44, the rotation axis of the first spindle 5, and the swing axis of the swing axis 35 in space coincides at one point, and this coincidence point is the center of the spherical cover. In this way, it can ensure that the contact forces in the contact area between the polishing head 10 and the workpiece 11 are consistent during grinding and polishing. Therefore, it is difficult to ensure the uniformity of the movement trajectories of abrasive grains on the surface of the spherical cover, and it is difficult to ensure the surface roughness and roundness during the processing of the spherical cover. It can ensure the uniformity of the movement trajectories of abrasive grains on the surface of the spherical cover, improve the surface quality. On the other hand, it increases the contact area between the spherical cover and the processing head, and can greatly improve the overall processing efficiency.

[0052] In some embodiments, the machine body 17 includes a machine table and a frame installed on the machine table; the movement mechanism includes: a first driving mechanism and a second driving mechanism. The first driving mechanism is installed on the frame and is used to move along the first horizontal direction X; the second driving mechanism is installed on the first driving mechanism and is used to move along the vertical direction Z. The first spindle 6 is installed on the second driving mechanism. The third driving mechanism is installed on the machine table and is used to move along the second horizontal direction Y. The first horizontal direction X and the second horizontal direction Y are perpendicular.

[0053] It further includes a turntable 12. The turntable 12 is provided with a fourth driving mechanism for driving the second spindle 44 to rotate; the fifth driving mechanism is installed on the third driving mechanism, and the turntable 12 is installed on the fifth driving mechanism. The fifth driving mechanism is provided with a swing axis 35, and the axial direction of the swing axis 35 is along the second horizontal direction Y. The fifth driving mechanism is used to drive the turntable 12 to swing. In this way, by controlling the first, second, third, fourth, and fifth driving mechanisms, automatic positioning and polishing of the workpiece can be achieved.

[0054] Among them, the fifth driving mechanism includes a fifth motor, a speed reducer connected to the fifth motor, and a swing axis 35 connected to the speed reducer; the output end of the swing axis 35 is provided with a swing arm 19, and the swing arm 19 is perpendicular to the swing axis 35; one end of the swing arm 19 far from the swing axis 35 is provided with an installation table extending horizontally. The turntable 12 is installed on the installation table and is located on the side of the installation table close to the swing arm 19. The axis of the second spindle 44 is perpendicular to the extending direction of the installation table.

[0055] In this embodiment, the first main shaft 5 is mounted on the Z-axis cross slide 34 through the first main shaft base 6, and a polishing head 11 is provided at the end of the first main shaft 6. The turntable assembly is fixed in the middle of the machine body 18 and includes a turntable 13, a turntable housing 15, a second main shaft 44, a frameless torque motor rotor 42, a frameless torque motor stator 43, and a turntable connecting shaft 45. The second main shaft fixes the spherical cover workpiece 12 through a clamping head 46. The turntable flange cover plate 41 closes the front end of the turntable housing 15, and the pneumatic rotary joint 40 is integrated inside the turntable connecting shaft 45. The frameless torque motor stator 43 is directly embedded in the turntable housing (5 to eliminate the backlash of gear or belt drive. The angular resolution of the turntable reaches 0.0001°, and the speed fluctuation < 0.1%. The pneumatic rotary joint 40 is integrated inside the turntable connecting shaft 45 to realize the dual functions of polishing liquid cooling and airtightness, avoiding the interference of external pipelines on the movement track.

[0056] In some embodiments, a center distance adjustment motor 21 is provided between the swing arm 19 and the moving table 20. The adjustment motor 21 is used to adjust the axial distance between the moving table 20 and the turntable 13. The laser displacement sensor 22 can detect the workpiece processing position error in real time and feedback it to the control system.

[0057] In some embodiments, a polishing liquid supply system is further included, which includes polishing liquid nozzle brackets 14, 47, polishing liquid nozzles 48, and a pneumatic rotary joint 40. The adjustable-angle polishing liquid nozzle 48 deflects synchronously with the movement track of the polishing head 11, reducing material waste and solving the problem of polishing liquid splashing at the edge of the special-shaped workpiece. The polishing liquid supply system includes polishing liquid nozzle brackets 14, 47, polishing liquid nozzles 48, and a pneumatic rotary joint 40. In some embodiments, in the polishing liquid supply system, the polishing liquid nozzle brackets 14, 47 are mounted on the Y-axis linear guide 16 through the Y-axis moving table cross slide 25. The angle of the polishing liquid nozzle 48 is adjustable, and the spraying direction is synchronous with the movement track of the cup-shaped polishing head 11.

[0058] See Figure 1 and Figure 2, in some embodiments, the whole machine adopts a vertical gantry layout structure. The first driving mechanism includes an X-axis linear guide rail installed on the frame, an X-axis linear guide rail slider, an X-axis sliding plate, an X-axis ball screw, an X-axis screw nut seat, and an X-axis servo motor 2; the third driving mechanism includes a Y-axis linear guide rail 15 installed on the machine table, a Y20-axis linear guide rail 15 slider, a Y20-axis moving table, a Y20-axis ball screw, a Y20-axis screw 16 nut seat, and a Y20-axis servo motor; the second driving mechanism is used to drive the polishing head to achieve two-dimensional movement in the vertical plane and adjust the polishing force. The second driving mechanism includes a Z-axis linear guide rail, a Z-axis linear guide rail slider, a Z-axis sliding plate 7, a Z-axis ball screw, a Z-axis screw 8 nut seat, and a Z-axis servo motor; the second driving mechanism is installed on the first driving mechanism to drive the first spindle on the Z-axis sliding plate 7 to move on the Z-axis, for adjusting the polishing force of the polishing head; the swing arm 19 is connected to the moving table of the third driving mechanism, and the turntable 12 is swung by a motor drive, and the maximum swing angle can be

[0059] ±60°; the turntable 12 structure is fixed on the swing arm, and the position is controlled by the servo motor of the center distance adjustment unit to ensure the coincidence of the ball center of the spherical cover and the swing center. The turntable 12 is driven to rotate by the frameless torque motor of the fourth driving mechanism.

[0060] The machine body 18 is the basic support structure of the equipment, and the gantry columns 1 are vertically fixed on both sides of the machine body 18. The first driving mechanism (X-axis movement component), the second driving mechanism (Y-axis movement component), and the third driving mechanism (Z-axis movement component) are installed on the machine body. The gantry columns 1 and the machine body 18 can form a closed frame through the reinforcing ribs 20, and cooperate with the shock-absorbing gaskets 36 to suppress the machining vibration, and the overall natural frequency of the equipment

[0061] ≥200Hz, to avoid accuracy loss caused by resonance. Compared with the open C-frame structure, the rigidity is improved and it is suitable for processing high-hardness materials (such as silicon carbide).

[0062] The X-axis movement component is installed on the top of the gantry column 1, and it includes an X-axis servo motor 3, an X-axis screw 4, an X-axis linear guide rail 5, and an X-axis linear guide rail slider 32. The X-axis movement component further includes X-axis screw rear supports (26, 27), which are respectively connected to both ends of the X-axis screw (4) through couplings (31); an X-axis nut seat (33), which is fixed on the X-axis linear guide rail slider (32) and is in threaded cooperation with the X-axis screw (4). The traditional single-support screw is prone to drift due to thermal deformation. The X-axis screw rear supports 26, 27 of this application adopt a pre-tightened double-bearing design, and the axial stiffness is increased to 500N / μm. The coaxiality deviation between the motor and the screw is eliminated by cooperating with the coupling (31), ensuring that the X-axis repeat positioning accuracy ≤ ±0.002mm.

[0063] The Y-axis movement component is installed on the front side of the bed 18, and includes a Y-axis servo motor 39, a Y-axis lead screw 17, a Y-axis linear guide 16, and a Y-axis linear guide slider 38. The Z-axis movement component is connected below the X-axis movement component and includes a Z-axis servo motor 30, a Z-axis lead screw 9, Z-axis linear guides 23, 28, Z-axis linear guide sliders 24, and Z-axis slides 7, 8, 34.

[0064] In this application, by integrating the X / Y / Z three-axis linear movement components and the turntable component, five-axis linkage control (X / Y / Z linear axes + turntable rotation axis + swing arm angle adjustment) is achieved, enabling full-directional polishing of complex workpieces such as spherical and asymmetric surfaces. The machining accuracy reaches ±0.001 mm, and the surface roughness Ra ≤ 0.01 μm. Traditional three-axis equipment requires multiple setups, while this solution can complete multi-angle machining with a single setup, increasing the efficiency by more than 50%.

[0065] The Z-axis movement component is a multi-stage linkage structure, which includes a first-stage Z-axis slide 7, which is connected to the X-axis movement component through the Z-axis linear guide 23; a second-stage Z-axis slide 8, which is driven to move vertically through the Z-axis lead screw 9; and a third-stage Z-axis moving table slide 34, which carries the electric spindle 6 and is equipped with a torque sensor 10. The three-stage Z-axis slides 7 / 8 / 34 are linked with the torque sensor (0 through a counterweight 34 to dynamically balance the axial load of the first spindle 6, so that the Z-axis maintains a positioning accuracy of ±0.003 mm under a load of 10 - 500 N. The traditional single-stage Z-axis is prone to flexural deformation under heavy loads, and this solution expands the processing range of the equipment (applicable to both micro-precision parts and large molds).

[0066] In some embodiments, the polishing head 10 can be coaxially connected to the output end of the first spindle 5 at the bottom of the Z-axis slide through an HSK63 tool holder interface. The contact area of the interface taper surface ≥ 85%, and the coaxiality between the axis of the polishing head and the rotation axis of the first spindle 5 ≤ 0.003 mm. The polishing head base is nested in the flange of the first spindle through a taper fit, and the inner cavity polishing surface of the polishing head is arranged coaxially with the axis of the first spindle; the chamfered end surface of the polishing head is equally spaced with 6 - 8 polishing liquid diversion grooves in the circumferential direction, and the groove depth is 1 / 4 - 1 / 2 of the thickness of the polishing wheel; a ring-shaped flange is provided on the outer diameter side wall of the polishing head, and a counterweight balance block is fixed on the upper surface of the flange. The tungsten alloy counterweight (density 17.5 g / cm 3 ) is provided with a three-stage adjustment structure: Coarse adjustment: 6 groups of M5 threaded holes in the circumferential direction, with a hole position spacing of 60°, and the mass tolerance of the counterweight is ±0.1 g; Fine adjustment: Steel balls with a diameter of φ2 mm are embedded at the bottom of the counterweight, and the center of mass is finely adjusted through an eccentric screw (adjustment amount ±0.5 mm); Dynamic compensation: When the polishing head rotates, a built-in piezoelectric accelerometer (model PCB 35Z moving table slide 2C03) detects vibrations in real time, and the counterweight is driven to move radially by the servo motor (resolution 0.01 mm).

[0067] In some embodiments, the groove profile parameters of the flow guiding groove of the polishing head are as follows: the width of the inlet section is 2 mm, the depth is 1.5 mm, and the expansion angle is 8°; the middle section: tapers to a width of 1.2 mm, a depth of 0.8 mm, and the bottom fillet of the groove is R0.2 mm; the outlet section: tangentially connects with the outer diameter of the polishing head. After such a setting, computational fluid dynamics (CFD) simulation verifies that the uniformity of the polishing liquid flow velocity distribution > 85%, and the turbulence intensity is reduced to 12%. The dynamic balance system enables the vibration velocity of the polishing head at a specific rotational speed ≤ 0.6 mm / s (ISO10816-3 Class B), and optimizing the flow guiding groove reduces the polishing liquid consumption by 40%.

[0068] In this embodiment, the clamping head 46 is provided with an adsorption surface, and the adsorption surface adsorbs the workpiece 11 through vacuum. The clamping head 46 is fixedly connected to the upper end of the second main shaft 44 by screws. The clamping head 46 includes a non-adsorption surface for supporting the workpiece and an adsorption surface that is the same arc surface as the non-adsorption surface. The area of the adsorption surface is 1 / 4 of the non-adsorption area. In this way, on the one hand, the workpiece can be stably supported, and the frictional force and adsorption force can be ensured, and the workpiece can be prevented from sliding on the surface of the clamping head during polishing.

[0069] The upper journal of the second main shaft 44 is assembled with a double-row angular contact bearing group 451 through a liquid nitrogen cold fitting process. The preload of the angular contact bearing group 451 is set to 500 - 800 N. The lower spline shaft of the second main shaft 44 is connected to the output end of the B-axis harmonic reducer by an involute spline. A vacuum channel is provided inside the second main shaft 44. The vacuum channel spirally surrounds the inner hole of the second main shaft 44 along the axis of the second main shaft 44, for example, in the form of a spiral groove. The end of the vacuum channel is connected to a pneumatic rotary joint; the clamping head 46 is coaxially installed at the top flange of the second main shaft 44 through a spigot positioning. The clamping head 46 is provided with an annular adsorption groove, and the annular adsorption grooves are equidistantly distributed radially on the clamping head. Among them, the spiral angle of the spiral groove is 15° ± 0.5°, and the lead is 120 mm; the cross-section of the groove is semi-circular (radius R = 2 mm), and the bottom of the groove is polished to Ra0.05 μm; the distance between adjacent grooves is 8 mm, and the pneumatic rotary joint is milled by a five-axis linkage machining center. The flange of the joint and the end face of the second main shaft 44 adopt a metal wound gasket sealing surface and apply perfluoromethyl ether grease, and the leakage rate ≤ 1×10 - 6 Pa·m 3 / s. In the solution of the present application, the spiral vacuum channel enables the air flow velocity to reach 25 m / s (the traditional straight groove structure is only 18 m / s), and the floating nut seat structure at the bottom of the second main shaft improves the repeat positioning accuracy to 0.0015 mm (VDI34 standard).

[0070] In this embodiment, the chuck 46 includes a base body and a silica gel protection pad. A positioning pin hole is provided at the bottom of the base body, and the positioning pin hole and the positioning pin of the flange of the first spindle 6 form an H7 / g6 transition fit; the perpendicularity between the measuring surface of the reference ring and the axis of the first spindle is finely adjusted by three circumferentially evenly distributed adjusting jackscrews; the silica gel protection pad is snap-fitted on the surface of the base body through a dovetail groove, and its edge is provided with an anti-overflow flanging with a thickness of 0.5 mm.

[0071] The solution of this application further includes a detection system. The detection system includes a first position detection device provided on the first driving mechanism. The position detection device is provided with a detection head 22. The detection head 22 is used to align with the edge of the workpiece 11 and is used to detect the lateral position of the workpiece 11 through the displacement deviation of the edge after the workpiece 11 rotates one week. The detection head is eccentrically installed on the right side surface of the Z-axis slide plate through a micrometer adjusting bracket with scales. The contact surface between the bracket base and the slide plate is provided with a V-shaped positioning groove. The laser emission direction forms an angle of 58°±2° with the axis of the polishing head, and the diameter of the measurement light spot is ≤0.1 mm.

[0072] The detection head 22 can be a laser displacement meter. The laser displacement meter is fixed on the Z-axis slide plate through a mounting bracket. The laser beam emitted by the laser displacement meter is along the vertical direction Z, and the laser beam emitted by it is parallel to the longitudinal center line of the chuck 46. There is a set distance between the laser beam and the longitudinal center line of the chuck 46. During operation, the laser probe is aligned with the spherical cover workpiece 11 and the rotation of the turntable 12 is used to detect whether the installation of the workpiece 11 meets the requirements.

[0073] In some embodiments, the laser displacement meter is eccentrically installed on the right side surface of the Z-axis slide plate through an adjustable bracket, and its laser emission direction forms an angle of 55°-60° with the axis of the polishing head; the laser displacement meter includes three groups of laser measuring heads distributed at equal angles of 120° and is connected to the Z-axis detection bracket through a ball hinge; the parallelism between the measurement reference plane and the X-Y20 plane of the machine tool coordinate system is adjusted to ≤0.005 mm; the reflection signal receiver is distributed in a ring around the laser emitter through an optical fiber bundle to form a coaxial detection optical path.

[0074] In some embodiments, the first position detection device further includes a torque sensor 10, a center distance adjustment motor 21, and an X-axis proximity switch 29. A multi-dimensional feedback system is composed of the torque sensor 10, the laser displacement meter 22, and the encoder 43 to correct the tool path and polishing pressure in real time, and solve the problem of error accumulation caused by tool wear or workpiece deformation in traditional open-loop control. The torque sensor 10 monitors the axial load torque of the first spindle 5 in real time and detects the machining pressure along the Z-axis (vertical direction) to prevent workpiece damage caused by overload.

[0075] The center distance adjustment motor 21 is close to the mounting base of the turntable assembly 13. It is rigidly connected to the swing shaft 35 through a coupling, driving the moving table 20 to move in the Y-axis direction, so as to adjust the center distance between the polishing head 11 and the turntable 13, and adapt to workpieces with different curvatures. The proximity switch 29 is fixed at the end of the X-axis linear guide 4 and aligned with the trigger piece on the X-direction nut seat 33, which can detect the extreme position of the X-axis movement and trigger the soft limit signal to prevent collision. The torque sensor transmits the torque signal to the main control unit through a shielded cable to dynamically adjust the Z-axis feed speed. The center distance adjustment motor 21 has an in-built encoder to form a closed loop with the control system, achieving center distance adjustment at the level of ±0.01 mm. The X-axis proximity switch 29 is directly connected to the emergency stop module by a hard wire, directly cutting off the servo enable signal in case of overtravel. When the machining starts, the X-axis proximity switch 29 confirms the initial position → the center distance adjustment motor 21 moves according to the preset curvature parameters → the torque sensor 10 real-time feeds back the load and corrects the path.

[0076] In this embodiment, the spherical cover is installed on the clamping head 46 by vacuum adsorption and rotates around the C-axis and swings around the B-axis together with the turntable 12. In order to achieve more accurate clamping and positioning and avoid large errors during machining, a high-precision laser displacement meter is installed on the X-axis slide plate through a bracket. Move the X-direction moving unit and the Y20-direction moving unit to align the laser displacement meter with the spherical cover and rotate the spherical cover one week by using the turntable 12, and detect the change of the displacement value during the whole process to judge the accuracy of the clamping position. The high-precision laser displacement meter has a simple structure, high measurement accuracy, strong anti-interference ability, and is almost not affected by the material and shape. It can also effectively measure the distance to the surface of the transparent and semi-transparent spherical cover, and determine the accuracy of the installation and positioning of the spherical cover accordingly.

[0077] The detection system further includes a second position detection device, which is arranged on the machine tool and in the axial direction of the swing shaft 35. The second position detection device is used to obtain the longitudinal profile image of the workpiece 11 and detect the position of the workpiece 11 relative to the axis of the swing shaft 35 based on the longitudinal profile image. If the center of the sphere of the workpiece 11 is not on the axis of the swing shaft 35, the motion mechanism is controlled to operate to adjust the position of the workpiece 11 until the center of the sphere of the workpiece 11 is not on the axis of the swing shaft. When the lateral position of the workpiece is deviated by detecting the displacement deviation at the edge after the workpiece 11 rotates one week, adjust the first motion mechanism and the third motion mechanism until the center of the sphere of the workpiece is located on the vertical rotation axes of the first and second main shafts.

[0078] The solution of this application consists of a torque sensor 10, a laser displacement meter 22 and an encoder to form a multi-dimensional feedback system, which can correct the tool path and polishing pressure in real time, and solve the problem of error accumulation caused by tool wear or workpiece deformation in traditional open-loop control. The X / Y / Z three-axis linear motion components and the turntable 13 form a five-axis linkage system, which can cooperate with the frameless torque motors 42-43 to achieve an angular indexing accuracy of ±0.001° for the turntable, meeting the all-directional machining requirements of asymmetric curved surfaces. The laser displacement meter 22 can detect the workpiece morphology in real time, fuse with the torque sensor (0 data, dynamically correct the Z-axis feed amount, and control the contour error within ±1μm.

[0079] In some embodiments, the turntable 12, the connecting shaft 46 and the second main shaft 44 are connected by screws. The torque motor rotor 42 is installed on the rotor installation shaft section, and the stator 43 is installed on the housing. The second main shaft 44 adopts a hollow shaft design to facilitate the layout of the vacuum channel. A clamping head 46 is installed on the turntable 12 to clamp the spherical cover to be machined, and a pneumatic rotary joint is connected at the bottom through threads to connect the vacuum tube. Set an appropriate vacuum degree to adsorb the spherical cover on the clamping head. The drive mode is selected as direct drive by a high-performance frameless torque motor. The direct drive method removes the intermediate transmission structure, making the overall structure of the turntable 12 more compact and the rotation accuracy higher.

[0080] When the direct-drive turntable 12 is working, sufficient torque will be generated between the stator 43 and the rotor 42 of the torque motor, and under the support of the bearings 443 and 451, the fixedly connected turntable 12, the connecting shaft and the rotor installation shaft section will rotate. Then, the workpiece can be adsorbed and fixed on the clamping head through vacuum negative pressure, and then the grinding and polishing work of the inner and outer spherical surfaces can be completed in cooperation with the tool.

[0081] In some embodiments, the frameless torque motor stator 43 is directly embedded in the turntable housing 15 to eliminate the backlash of gear or belt drive. The angular resolution of the turntable reaches 0.0001°, and the speed fluctuation <0.1%. The pneumatic rotary joint 40 is integrated inside the turntable connecting shaft 45 to achieve the dual functions of polishing liquid cooling and airtight sealing, avoiding interference of the external pipeline with the motion trajectory. In the solution of this application, the frameless torque motor is directly embedded inside the turntable housing 15 by the rotor 42 and the stator 43, realizing zero-backlash high-precision rotation of the turntable 13.

[0082] The specific working process of this embodiment is as follows: First, process the corresponding inner and outer chucks 46 according to the size of the spherical cover. Connect the chuck 46 to the C-axis turntable 12 and use a laser displacement meter to detect the installation position of the spherical cover. Adsorb and fix the spherical cover on the chuck 46 by adjusting the vacuum adsorption force, and adjust the position of the center of the spherical cover to make the center of the spherical cover coincide with the swing center. Input the polishing parameters such as the rotation speed of the second spindle 44, the rotation speed of the turntable 12, the swing speed of the swing axis 35, the polishing pressure, the polishing liquid flow rate, and the polishing time to polish the surface of the spherical cover. The swing speed of the swing axis is less than 50 r / min; the swing angle of the swing axis is -60 - 60 degrees. After polishing, detect the polishing result. If the detection result is unqualified, re-correct the polishing parameters and continue polishing until the surface detection meets the requirements. After one side is polished, replace the chuck and polish the other surface of the spherical cover until the detection is qualified.

[0083] In some embodiments, it further includes an error compensation system. The error compensation system includes: a laser interferometer mirror group, which is installed on the reference planes on both sides of the machine body through a magnetic base and forms an optical path for the 45 second spindle 44 with each axis measurement mirror group; the error compensation table data is uploaded to the control system through an interface, and the compensation instruction preferentially executes the flatness compensation of the X / Y20 axis plane; the scraping compensation amount of the guide rail is distributed according to the

[0084] Δ = 0.8L + 1.2 (μm) formula, and the scraping depth gradient decreases. The mirror group includes: an X-axis measurement mirror: about 30X-axis proximity switches 0 mm from the front end of the machine body, and the height is flush with the axis of the first spindle (±0.1 mm). A Y20-axis measurement mirror: installed on the side of the base of the turntable 12, and the parallelism between the mirror surface and the Y20-axis guide rail

[0085] ≤0.005 mm / 1000 mm. A Z-axis measurement mirror: adsorbed on the top of the crossbeam through a magnetic base, and the included angle between the normal of the mirror surface and the Z-axis is ≤15″; the optical path calibration process includes rough adjustment and fine adjustment. During rough adjustment, the deviation between the center of the laser beam and the axis of the guide rail is ≤±1 mm. During fine adjustment, use a five-dimensional adjustment frame (resolution 0.001 mm / 0.1″) to make the interference fringe contrast > 90%.

[0086] The solution of this application is based on the multi-body system model to establish the mapping relationship between the static deformation of the X / Y / Z-axis guide rails and the polishing trajectory error. The simulation results show that: the concave deformation in the middle section of the X-axis guide rail (up to 15.92 μm) leads to uneven distribution of the polishing pressure, resulting in excessive material removal in the equatorial region of the spherical cover; the warping at both ends of the Y-axis guide rail (12.7 μm) causes the deviation of the swing axis center, affecting the accuracy of spherical generation; the linear deformation of the Z-axis (8.4 μm) changes the polishing contact area, resulting in fluctuations in the axial removal rate. These errors are directly manifested as the out-of-tolerance of the PV value of the spherical cover surface profile (>8 μm) and uneven surface roughness (Ra 0.2 - 0.6 μm). Targeted compensation is implemented according to the error characteristics: for the X-axis, quadratic curve scraping (maximum scraping amount 12.8 μm) is adopted, combined with closed-loop control of the polishing pressure, to reduce the fluctuation of the removal rate in the equatorial region from ±15% to ±5%; for the Y-axis, step-by-step scraping at both ends (maximum 9.6 μm) is carried out, combined with the B-axis swing angle compensation algorithm, to compress the spherical center positioning error from 23 μm to 5 μm and improve the spherical roundness to 0.8 μm; for the Z-axis, linear scraping (maximum 6.3 μm) is used to synchronously optimize the feed speed curve, increasing the consistency of axial material removal by 40%.

[0087] Verification of the improvement of the polishing effect. The machining test after compensation shows that: in terms of surface profile accuracy, the PV value of the spherical cover is reduced from 7.6 μm before compensation to 2.3 μm, better than the requirement of 4 μm in the national defense standard GJB2485-95; in terms of surface quality, the roughness Ra is optimized from 0.32 μm (fluctuating ±0.18 μm) to 0.08 ± 0.02 μm, and the light transmittance is increased by 12%; in terms of machining efficiency, due to the improvement of the trajectory accuracy, the fine polishing time is shortened from 45 min per piece to 28 min, and the depth of the subsurface crack is reduced from 3.2 μm to 0.8 μm;

[0088] Therefore, this application innovatively combines mechanical compensation with dynamic adjustment of process parameters. Through systematic correction of the error source, the motion matching degree between the polishing tool and the spherical surface is increased by 37%, effectively solving defects such as "coma" and "horseshoe marks" caused by machine tool deformation in the polishing of hard and brittle materials.

[0089] The embodiments of this application have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technologies in the market, or to enable other ordinary skill in the art in the technical field to understand the embodiments disclosed herein.

Claims

1. A polishing device, characterized in that: include: A machine body, wherein a motion mechanism is provided on the machine body; A first spindle and a second spindle, the motion mechanism is used to drive the first spindle to rotate around the axis of the spindle; a polishing head is provided at the lower end of the first spindle; a chuck is provided at the upper end of the second spindle, the chuck is used to mount a workpiece with a spherical surface, and the motion mechanism is also used to drive the second spindle to rotate; A swing shaft, wherein the swing shaft is perpendicular to the first and second main shafts, the second main shaft is drivingly connected to the swing shaft, and the motion mechanism is further used to drive the second main shaft to swing in a vertical plane through the swing shaft; The first spindle and the second spindle are coaxial in the vertical direction, the axes of the first spindle and the second spindle intersect with the axis of the swing axis at a virtual point, and the virtual point coincides with the virtual spherical center of the chuck.

2. The polishing device according to claim 1, characterized in that: The machine body includes a machine platform and a frame installed on the machine platform; The motion mechanism comprises: A first driving mechanism and a second driving mechanism, wherein the first driving mechanism is mounted on the frame and is used to move in a first horizontal direction; the second driving mechanism is mounted on the first driving mechanism and is used to move in a vertical direction, and the first spindle is mounted on the second driving mechanism. A third driving mechanism, mounted on the machine platform, the third driving mechanism is used to move along a second horizontal direction, the first horizontal direction and the second horizontal direction being perpendicular; A turntable assembly, wherein the turntable assembly is provided with a fourth driving mechanism, and the fourth driving mechanism is used to drive the second spindle to rotate; The fifth driving mechanism is installed on the third driving mechanism, the turntable is installed on the fifth driving mechanism, the fifth driving mechanism is provided with the swing shaft, the axial direction of the swing shaft is along the second horizontal direction, and the fifth driving mechanism is used to drive the turntable to swing.

3. The polishing device according to claim 2, characterized in that: A first position detection device is provided on the first driving mechanism, wherein the position detection device is provided with a detection head, wherein the detection head is used to align with the edge of the workpiece and to detect the lateral position of the workpiece through the displacement deviation of the edge after the workpiece rotates one circle; The second position detection device is provided on the machine platform and is located in the axial direction of the swing shaft. The second position detection device is used to obtain a longitudinal profile image of the workpiece and detect the position of the workpiece relative to the axis of the swing shaft based on the longitudinal profile image.

4. The polishing device according to claim 2, characterized in that: The fifth driving mechanism includes a fifth motor, a reducer connected to the fifth motor, and the swing shaft connected to the reducer; a swing arm is provided at the output end of the swing shaft, and the swing arm is perpendicular to the swing shaft; a laterally extending mounting platform is provided at one end of the swing arm away from the swing shaft, the turntable is installed on the mounting platform and is located on a side of the mounting platform close to the swing arm, and the axis of the second main shaft is perpendicular to the extension direction of the mounting platform.

5. The polishing device according to claim 3, characterized in that: The first position detection device comprises a laser displacement meter, the laser beam emitted by the laser displacement meter is in a vertical direction, and the laser beam is parallel to the longitudinal center line of the chuck, and there is a set distance between the laser beam and the longitudinal center line of the chuck; The second position detection device includes an image collector, which is connected to a processor. The processor is used to determine the virtual sphere center of the workpiece based on the image collected by the image collector, and to determine whether the virtual sphere center is located at a preset coordinate origin, and the coordinate origin is located at the axis center of the swing axis.

6. The polishing device according to claim 1, characterized in that: The second spindle comprises a chuck, the chuck is provided with an adsorption surface, the adsorption surface adsorbs the workpiece by vacuum, and the chuck comprises a non-adsorption surface for supporting the workpiece, and an adsorption surface which is the same arc surface as the non-adsorption surface, and the area of ​​the adsorption surface is 1 / 4 of the non-adsorption area; A vacuum channel is provided in the second spindle, the vacuum channel spirally surrounds the inner hole of the second spindle along the axis of the second spindle, and the end of the vacuum channel is connected to a pneumatic rotary joint; The clamping head is coaxially mounted on the top flange of the second spindle through a stopper positioning, and the clamping head is provided with an annular adsorption groove, and the annular adsorption grooves are radially and equidistantly distributed on the clamping head.

7. The polishing device according to claim 1, characterized in that: The polishing head is cup-shaped and satisfies: The polishing head base is nested in the flange of the first spindle through a conical surface, and the inner cavity polishing surface of the polishing head is coaxially arranged with the axis of the first spindle; The chamfered end surface of the polishing head is provided with 6-8 polishing liquid guide grooves equidistantly arranged along the circumferential direction, and the groove depth is 1 / 4-1 / 2 of the thickness of the polishing wheel; An annular flange is arranged on the outer diameter side wall of the polishing head, and a counterweight balancing block is fixed on the upper surface of the flange.

8. The polishing device according to claim 1, characterized in that: Also included is an error compensation system, the error compensation system comprising: The laser interferometer reflector group is installed on the reference surfaces on both sides of the bed through a magnetic table base, forming a 45° optical path with the measuring mirror group of each axis; the error compensation table data is uploaded to the control system through the interface, and the compensation command gives priority to the X / Y axis flatness compensation; the guide rail scraping compensation amount is distributed along the length direction of the guide rail according to the formula Δ=0.8L+1.2 (μm), and the scraping depth gradient decreases.

9. The polishing device according to claim 5, characterized in that: The laser displacement meter is eccentrically mounted on the right side of the Z-axis slide plate through an adjustable bracket, and the laser emission direction of the laser displacement meter forms an angle of 55°-60° with the axis of the polishing head; The laser displacement meter includes three groups of laser probes distributed at 120° equal angles and connected to the Z-axis detection bracket through a ball joint; the parallelism between the measurement reference plane and the XY plane of the machine tool coordinate system is adjusted to ≤0.005mm; the reflected signal receiver is distributed in a ring around the laser transmitter through the optical fiber bundle to form a coaxial detection optical path.

10. The polishing device according to claim 1, characterized in that: The chuck comprises: The base body has a positioning pin hole at the bottom thereof, and the positioning pin hole forms an H7 / g6 transition fit with the positioning pin of the first spindle flange; the verticality of the reference ring measuring surface and the first spindle axis is fine-tuned by three circumferentially evenly distributed adjusting screws; The silicone protective pad is clamped on the surface of the base body through a dovetail groove, and an anti-overflow flange with a thickness of 0.5 mm is provided on its edge.

Images