A polishing device for the surface of an optical element

Abstract

A polishing device for the surface of an optical element, which relates to the field of optical ultra-precision machining. To solve the problem that the polishing shaft rotates around its own axis while also revolving around another axis, resulting in unstable movement during the rotation of the polishing head and affecting the polishing accuracy of the surface of the optical element. The present invention includes a polishing head, a polishing shaft, a polishing shaft revolving mechanism, and a polishing shaft rotating mechanism; the power output end of the polishing shaft revolving mechanism is connected to the polishing shaft and drives the polishing shaft to revolve; the polishing shaft rotating mechanism uses a synchronous belt group to drive the polishing shaft to rotate, and a belt tensioning assembly is used to tension the transmission belt; the polishing head is connected to the polishing shaft and rotates and revolves with the polishing shaft; when the polishing shaft revolving mechanism and the polishing shaft rotating mechanism drive the polishing shaft to perform revolving and rotating movements, as the center distance between the polishing shaft and the motor shaft of the rotating motor changes, the belt tensioning assembly contacts and tensions the transmission belt, so that the torque of the motor shaft of the rotating motor is stably transmitted to the polishing shaft. The present invention is used for polishing optical elements.

Description

Technical Field

[0001] The present invention relates to the field of optical ultra-precision machining, and particularly to a polishing device for the surface of an optical element. Background Art

[0002] With the rapid development of modern optical systems, more and more cutting-edge fields require the use of high-precision and large-aperture optical elements. Therefore, various ultra-precision machining technologies are continuously developing towards high quality, high stability, and high efficiency.

[0003] At present, the small-tool polishing process based on industrial robots has unique advantages such as low cost and large processing range, and has been widely used in the polishing of various optical elements. In this polishing process, the small tool head rotates and revolves simultaneously on the surface of the optical element. That is, the polishing actuator needs to ensure that the small tool head rotates while performing eccentric motions at different distances around a certain axis during the polishing process, so as to form a Gaussian removal function on the surface of the optical element and improve the machining accuracy of the workpiece surface. However, at the same time, in order to meet the above-mentioned motion states, this polishing process uses flexible torque transmission components such as flexible shafts and telescopic universal joints to achieve the transmission of the rotation torque. For example, in the "A Rigid Eccentric Drive Rotation and Revolution Pneumatic Force Application Numerical Control Polishing Device" disclosed in the publication number CN102962764B, the flexible torque transmission components will cause the small tool head to move unstably during rotation, still affecting the polishing accuracy of the surface of the optical element. Summary of the Invention

[0004] In view of this, the present invention provides a polishing device for the surface of an optical element. When the polishing shaft revolution mechanism and the polishing shaft rotation mechanism drive the polishing shaft to perform revolution and rotation motions, as the center distance between the polishing shaft and the motor shaft of the rotation motor changes, the belt tensioning assembly is used to always tension the transmission belt, so as to stably transmit the torque of the motor shaft of the rotation motor to the polishing shaft.

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

[0006] A polishing device for the surface of an optical element, comprising a polishing execution mechanism, a polishing shaft revolution mechanism, and a polishing shaft rotation mechanism; the polishing execution mechanism includes a polishing head and a polishing shaft, the power output end of the polishing shaft revolution mechanism is connected to the polishing shaft and drives the polishing shaft to revolve; the power output end of the polishing shaft rotation mechanism is connected to the polishing shaft and drives the polishing shaft to rotate; the polishing head is connected to the polishing shaft and rotates and revolves with the polishing shaft; the polishing shaft rotation mechanism includes a rotation motor, a driving wheel, a driven wheel, a transmission belt, and a belt tensioning assembly, the driving wheel is connected to the motor shaft of the rotation motor and rotates with the motor shaft, the driven wheel is sleeved on the polishing shaft and drives the polishing shaft to rotate, the transmission belt is sleeved on the driving wheel and the driven wheel, and the belt tensioning assembly contacts and tensions the transmission belt; when the polishing shaft revolution mechanism and the polishing shaft rotation mechanism drive the polishing shaft to perform revolution and rotation movements, as the center distance between the polishing shaft and the motor shaft of the rotation motor changes, the belt tensioning assembly contacts and tensions the transmission belt, so that the torque of the motor shaft of the rotation motor is stably transmitted to the polishing shaft.

[0007] Further, the belt tensioning assembly includes a guide shaft, a tensioning wheel, and a tension spring, the guide shaft is fixed to one side of the transmission belt; the tensioning wheel is connected to the guide shaft and can move axially along the guide shaft, the tension spring is sleeved on the guide shaft and presses the tensioning wheel; when the center distance between the motor shaft of the rotation motor and the polishing shaft changes, the tension spring presses the tensioning wheel, so that the tensioning wheel presses and keeps the transmission belt tensioned.

[0008] Further, the polishing shaft revolution mechanism includes a revolution motor, a revolution shaft, and an eccentricity adjustment assembly; the eccentricity adjustment assembly connects the motor shaft of the revolution motor and the revolution shaft, when the eccentricity adjustment assembly adjusts the eccentricity between the motor shaft of the revolution motor and the revolution shaft, the mass of the polishing shaft revolution mechanism is symmetrically distributed with the motor shaft of the revolution motor as the center, so as to ensure the dynamic balance during the movement of the polishing shaft revolution mechanism.

[0009] Further, the eccentricity adjustment assembly includes a dynamic balance counterweight, a revolution shaft connecting block, a central gear, and two racks; the revolution shaft is connected to the revolution shaft connecting block and moves with the revolution shaft connecting block; the dynamic balance counterweight and the revolution shaft connecting block are each connected to a rack, and the two racks are engaged with the central gear; when the central gear rotates, the two racks drive the connected dynamic balance counterweight and revolution shaft connecting block to move relative to each other with the motor shaft of the revolution motor as the center, an eccentricity is generated between the revolution shaft and the motor shaft of the revolution motor, and at the same time, the mass of the dynamic balance counterweight and the mass of the revolution shaft connecting block and the revolution shaft are symmetrically distributed with the motor shaft of the revolution motor as the center.

[0010] Furthermore, the polishing shaft revolution mechanism further includes a transmission box and a cross guide rail. The transmission box is sleeved outside the revolution shaft and moves with the revolution shaft. The cross guide rail is connected to the transmission box and limits the movement of the transmission box. The polishing shaft is connected to the transmission box and moves with the transmission box. When the revolution shaft revolves around the motor shaft of the revolution motor, the transmission box makes a revolution movement under the limitation of the cross guide rail, so that the polishing shaft makes a revolution movement around the polishing point on the surface of the workpiece.

[0011] Furthermore, the eccentricity adjustment component further includes an eccentricity calibration scale and a pointer for measuring the eccentricity. The eccentricity calibration scale is installed on the transmission box, and the pointer is installed above the eccentricity calibration scale and points to the eccentricity calibration scale. When adjusting the eccentricity, the transmission box moves with the revolution shaft, and a displacement is generated between the eccentricity calibration scale and the pointer to realize the measurement of the eccentricity.

[0012] Furthermore, the polishing execution mechanism further includes a rotary joint. The rotary joint is installed at the top end of the polishing shaft and can rotate. The rotary joint and the polishing shaft are both provided with liquid supply channels and are communicated with each other. The polishing head is provided with a central hole and is communicated with the liquid supply channel of the polishing shaft.

[0013] Furthermore, the polishing execution mechanism further includes a pressure adjustment cylinder, a pressure transmission rod and a pressure sensor for adjusting the contact pressure between the polishing head and the surface of the workpiece. The pressure adjustment cylinder is arranged on one side of the polishing shaft. The cylinder body of the pressure adjustment cylinder is installed on the transmission box. The pressure transmission rod connects the polishing shaft and the telescopic rod of the pressure adjustment cylinder. The pressure sensor is installed between the pressure transmission rod and the polishing shaft. When the pressure transmission rod moves down with the telescopic rod, the pressure transmission rod drives the polishing head to move down and contact the surface of the workpiece, and the air pressure of the pressure adjustment cylinder is adjusted to change the contact pressure between the polishing head and the surface of the workpiece.

[0014] The beneficial effects of the present invention compared with the prior art are as follows:

[0015] 1. The polishing shaft rotation mechanism of the present invention uses a synchronous belt group to achieve the transmission of rigid torque over a long distance. The rotation motor is separated from the polishing shaft, avoiding the problem of increased moment of inertia caused by the rotation motor revolving with the polishing shaft. At the same time, when the polishing shaft revolution mechanism and the polishing shaft rotation mechanism drive the polishing shaft to make revolution and rotation movements, as the center distance between the polishing shaft and the motor shaft of the rotation motor changes, the belt tensioning assembly is used to always tension the transmission belt, so that the torque of the motor shaft of the rotation motor can be smoothly transmitted to the polishing shaft, ensuring the stability of the polishing shaft during rotation and improving the polishing accuracy of the workpiece surface.

[0016] 2. In the present invention, the eccentricity adjustment component uses the driving mode of a gear and a rack, such that the two racks respectively drive the dynamic balance counterweight blocks and the common rotating shaft connection blocks connected thereto to relatively move around the motor shaft of the revolution motor and move the same distance. The common rotating shaft connection block drives the common rotating shaft connected thereto to move, so as to generate an eccentricity between the common rotating shaft and the motor shaft of the revolution motor. At the same time, the dynamic balance counterweight blocks are used to balance the eccentric mass generated after the movement of the common rotating shaft connection block and the common rotating shaft, eliminating the problem of dynamic imbalance caused by uneven mass.

[0017] 3. The polishing shaft revolution mechanism in the present invention adopts the design of a transmission box and a cross guide rail. The cross guide rail decomposes the circular motion of the revolution of the transmission box into linear motions in two directions on a plane, supporting the transmission box without affecting the revolution motion of the transmission box. Moreover, the design of the transmission box and the cross guide rail not only realizes the separated design of the polishing shaft and the common rotating shaft and the transmission of the revolution motion, but also makes the motion of the polishing execution mechanism more stable, reduces the vibration of the polishing execution mechanism and the pressure sensor, and improves the polishing accuracy of the surface of the optical element.

[0018] 4. The present invention installs a rotary joint at the top of the polishing shaft to connect with a liquid hose, avoiding the problem that the polishing accuracy of the workpiece surface is affected due to the winding problem between the liquid hose and the polishing shaft.

[0019] 5. The present invention uses a low-friction air cylinder to adjust the contact pressure between the polishing grinding head and the workpiece surface, measures the contact pressure through a pressure sensor and realizes force feedback to control the air cylinder pressure output, achieving closed-loop control, making the normal contact pressure on the workpiece surface constant, and obtaining a more stable removal function. Description of the Drawings

[0020] The drawings, as a part of this application, are used to provide a further understanding of the present invention.

[0021] Figure 1 It is a schematic diagram of the overall structure of a polishing device for the surface of an optical element according to the present invention.

[0022] Figure 2 It is a schematic diagram of the internal structure of the polishing device.

[0023] Figure 3 It is a sectional view of the inside of the polishing device.

[0024] Figure 4 It is a schematic diagram of the structure of the eccentricity adjustment component.

[0025] Figure 5 It is an exploded view of the eccentricity adjustment component.

[0026] Figure 6 It is a sectional view of the eccentricity adjustment component.

[0027] Figure 7 is Figure 3 the partial enlarged view of A in

[0028] Figure 8 the structural schematic diagram of the belt tensioning assembly.

[0029] Explanation of the reference numerals in the drawings:

[0030] 1 - Robotic arm connection flange; 2 - Flange support frame; 3 - Support housing;

[0031] 4 - Polishing actuator, 41 - Polishing grinding head, 42 - Polishing shaft, 43 - Rotary joint, 44 - Pressure regulating cylinder, 45 - Pressure transfer rod, 46 - Pressure sensor, 47 - Spline nut;

[0032] 5 - Revolution mechanism of the polishing shaft, 51 - Revolution motor, 52 - Revolution shaft, 53 - Eccentricity adjustment component, 531 - Housing, 532 - Dynamic balance counterweight, 533 - Revolution shaft connection block, 534 - Adjusting knob, 535 - Driving bevel gear, 536 - Driven bevel gear, 537 - Central connection shaft, 538 - Central gear, 539 - Rack, 54 - Eccentricity calibration scale, 55 - Pointer, 56 - Transmission box, 57 - Cross guide rail;

[0033] 6 - Rotation mechanism of the polishing shaft, 61 - Rotation motor, 62 - Rotation shaft, 63 - Driving wheel, 64 - Driven wheel, 65 - Transmission belt, 66 - Belt tensioning assembly, 661 - Support, 662 - Guide shaft, 663 - Tensioning wheel, 664 - Wheel shaft, 665 - Tension spring. Specific implementation manners

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0035] Since the material removal function is related to the polishing accuracy of the workpiece surface, when the polishing head on the polishing shaft makes a planetary motion around a certain point on the workpiece, the removal function can be made Gaussian-shaped, improving the machining accuracy of the workpiece surface. In the prior art, generally, a rotation motor is directly connected to the polishing shaft to drive the polishing head to rotate. However, the rotation motor will revolve together with the polishing shaft, resulting in an increase in the mass of the driven revolving part, a substantial increase in the moment of inertia, and thus an increase in the vibration amplitude of the polishing shaft and the polishing head, unstable material removal, and affecting the machining accuracy of the workpiece surface. There are also some technologies that separate the rotation motor and the polishing shaft, but all use flexible torque transmission elements such as flexible shafts and telescopic universal joints to achieve the transmission of the rotation torque. This setting will cause unstable torque transmission, and further cause the polishing head to move unstably during rotation, still affecting the polishing accuracy of the optical element surface.

[0036] Therefore, referring to Figures 1 to 8, this embodiment provides a polishing device for the surface of an optical element, including a robotic arm connection flange 1, a flange support frame 2, a support housing 3, a polishing actuator 4, a polishing axis revolution mechanism 5 for the revolution of the polishing axis, and a polishing axis rotation mechanism 6 for the rotation of the polishing axis 42; the polishing device is connected to the robotic arm via the robotic arm connection flange 1 and moves with the robotic arm. The flange support frame 2 connects the robotic arm connection flange 1 and the support housing 3. The polishing axis revolution mechanism 5 and the polishing axis rotation mechanism 6 are installed in and supported by the support housing 3. The polishing actuator 4 includes a polishing head 41 and a polishing axis 42. The power output end of the polishing axis revolution mechanism 5 is connected to the polishing axis 42 and drives the polishing axis 42 to perform a revolution motion; the power output end of the polishing axis rotation mechanism 6 is connected to the polishing axis 42 and drives the polishing axis 42 to perform a rotation motion. The polishing head 41 is connected to the bottom end of the polishing axis 42 and rotates and revolves with the polishing axis 42. Specifically, the polishing axis rotation mechanism 6 includes a rotation motor 61, a rotation axis 62, a driving wheel 63, a driven wheel 64, a transmission belt 65, and a belt tensioning assembly 66. The motor housing of the rotation motor 61 is installed on the support housing 3. The top end of the rotation axis 62 is connected to the motor shaft of the rotation motor 61 through a coupling and rotates with the motor shaft. The bottom end of the rotation axis 62 is connected to the support housing 3 through a bearing and is rotatable; the driving wheel 63 is sleeved outside the rotation axis 62 and is key-connected to the rotation axis 62 to achieve torque transmission; a female rotary spline nut 47 is also sleeved outside the polishing axis 42. The spline nut 47 is key-connected to the polishing axis 42. The driven wheel 64 is sleeved on the polishing axis 42 and is fixedly connected to the spline sleeve of the spline nut 47. The transmission belt 65 is sleeved on the driving wheel 63 and the driven wheel 64, and the belt tensioning assembly 66 contacts and tensions the transmission belt 65; when the rotation motor 61 is turned on, the rotation motor 61 drives the rotation axis 62 to rotate, the driving wheel 63 rotates with the rotation axis 62, and the torque of the driving wheel 63 is transmitted to the driven wheel 64 through the transmission belt 65. The driven wheel 64 drives the polishing axis 42 to rotate through the spline nut 47; at the same time, the polishing axis revolution mechanism 5 drives the polishing axis 42 to perform a revolution motion, and the center distance between the polishing axis 42 and the rotation axis 62 changes. The belt tensioning assembly 66 always contacts and tensions the transmission belt 65 so that the torque of the rotation axis 62 can be stably transmitted to the polishing axis 42. The polishing axis rotation mechanism 6 of this embodiment uses a synchronous belt set to achieve the transmission of rigid torque over a long distance. The rotation motor 61 is separated from the polishing axis 42, avoiding the problem of increased moment of inertia caused by the rotation motor 61 revolving with the polishing axis 42.In addition, since the length of the transmission belt 65 is fixed, when the polishing shaft 42 makes a small-range revolution, as the center distance between the polishing shaft 42 and the self-rotating shaft 62 changes, the transmission belt 65 will become loose, affecting the transmission of the rigid torque between the driving wheel 63 and the driven wheel 64. Therefore, in this embodiment, the belt tensioning assembly 66 is used to always tension the transmission belt 65, so that the torque of the motor shaft of the self-rotating motor 61 can be smoothly transmitted to the polishing shaft 42, ensuring the stability of the polishing shaft 42 during self-rotation and improving the polishing accuracy of the workpiece surface.

[0037] See Figure 8 , in this embodiment, the belt tensioning assembly 66 includes a support 661, a guide shaft 662, a tensioning wheel 663, a wheel shaft 664 and a tensioning spring 665. The support 661 is installed on the support housing 3 and is located on one side of the transmission belt 65. The guide shaft 662 is fixedly installed on the support 661; one end of the wheel shaft 664 is sleeved on the guide shaft 662 and can move axially along the guide shaft 662. The tensioning wheel 663 is sleeved on the other end of the wheel shaft 664 and can rotate. At the same time, the outer circumferential surface of the tensioning wheel 663 contacts the transmission belt 65. The tensioning spring 665 is sleeved on the guide shaft 662 and is compressed, and the tensioning spring 665 contacts and presses the wheel shaft 664. When the center distance between the self-rotating shaft 62 and the polishing shaft 42 decreases, the tensioning spring 665 pushes the tensioning wheel 663 to move towards the transmission belt 65 side and always presses the transmission belt 65, and the transmission belt 65 is tensioned; when the center distance between the self-rotating shaft 62 and the polishing shaft 42 increases, the transmission belt 65 pushes the tensioning wheel 663 to move and presses the tensioning spring 665, and the tensioning spring 665 is compressed and stores a certain amount of elastic force. That is to say, with the cooperation of the tensioning spring 665 and the tensioning wheel 663, no matter how the center distance between the self-rotating shaft 62 and the polishing shaft 42 changes, the transmission belt 65 is always in a tensioned state, so the stable transmission of the torque between the driving wheel 63 and the driven wheel 64 can be realized.

[0038] See Figures 2 to 5, when facing different polished workpieces, the revolution range of the polishing shaft 42 needs to be adjusted, so it is necessary to adjust the eccentricity between the revolution shaft 52 and the motor shaft of the revolution motor 51. At present, the adjustment of the eccentricity generally uses moving pairs such as screw-nut pairs and sliding guides. This kind of eccentricity adjustment structure will cause the overall mass distribution of the polishing shaft revolution mechanism to be uneven after the eccentricity is adjusted, resulting in the dynamic imbalance of the revolution shaft. The dynamic imbalance of the revolution shaft will cause the vibration of the robotic arm and the actuator, resulting in unstable contact between the polishing head and the workpiece, and the contact force signal measured by the sensor also fluctuates, so that the accurate adjustment of the polishing force on the workpiece surface cannot be realized, affecting the machining accuracy of the workpiece surface. Therefore, the dynamic imbalance problem of the revolution part will lead to unstable material removal function and large machining errors. The dynamic imbalance of the rotor will cause the vibration of the robotic arm actuator, resulting in unstable contact, problems in force measurement, poor control of the contact force, and then unstable material removal function, affecting the machining accuracy.

[0039] Therefore, the polishing shaft revolution mechanism 5 in this embodiment includes a revolution motor 51, a reducer, a revolution shaft 52 and an eccentricity adjustment component 53; the motor shaft of the revolution motor 51 is connected to the eccentricity adjustment component 53 via the reducer, and the eccentricity adjustment component 53 is also connected to the revolution shaft 52. When the eccentricity adjustment component 53 adjusts the eccentricity between the motor shaft of the revolution motor 51 and the revolution shaft 52, the mass of the polishing shaft revolution mechanism 5 is symmetrically distributed with the motor shaft of the revolution motor 51 as the center to ensure the dynamic balance when the polishing shaft revolution mechanism 5 moves.

[0040] Specifically, in combination with Figure 3 , Figure 4 and Figure 5, in this embodiment, the eccentricity adjustment assembly 53 includes a housing 531, a dynamic balance counterweight 532, a common rotation shaft connection block 533, an adjustment knob 534, a driving bevel gear 535, a driven bevel gear 536, a central connection shaft 537, a central gear 538, and two racks 539; the housing 531 is a housing with an open bottom, and the motor shaft of the common rotation motor 51 is connected to the top of the housing 531 via a speed reducer and can drive the housing 531 to rotate; a balance weight guiding port and a reserved hole are formed on the side wall of the housing 531, and the balance weight guiding port and the reserved hole are arranged opposite to each other. The dynamic balance counterweight 532 is a shell-like structure with an open bottom, and at the same time, a waist-shaped hole is formed on the top of the dynamic balance counterweight 532. The dynamic balance counterweight 532 is inserted into the housing 531 through the balance weight guiding port, and the dynamic balance counterweight 532 can move along the balance weight guiding port. The common rotation shaft connection block 533 is arranged at the bottom of the housing 531 and can move relative to the housing 531. One end of the central connection shaft 537 passes through the waist-shaped hole at the top of the dynamic balance counterweight 532 and is rotatably connected to the housing 531, and the central gear 538 is connected to the other end of the central connection shaft 537 and rotates with the central connection shaft 537; the driving bevel gear 535, the driven bevel gear 536, the central connection shaft 537, the central gear 538, and the two racks 539 are all located inside the dynamic balance counterweight 532. One end of the adjustment knob 534 passes through the reserved hole on the housing 531 and is connected to the driving bevel gear 535. The other end of the adjustment knob 534 is a hexagonal knob. A hexagonal wrench is used to extend into the reserved hole to adjust the eccentricity, and the operation is simple. The driven bevel gear 536 is sleeved on the central connection shaft 537 and is meshed and connected to the driving bevel gear 535; each of the dynamic balance counterweight 532 and the common rotation shaft connection block 533 is connected to one rack 539, and the two racks 539 are meshed with the central gear 538; the common rotation shaft 52 is connected to the common rotation shaft connection block 533 and moves with the common rotation shaft connection block 533. In this embodiment, by manually rotating the adjustment knob 534, the driving bevel gear 535 drives the driven bevel gear 536 and the central connection shaft 537 connected to the driven bevel gear 536 to rotate. The central connection shaft 537 drives the central gear 538 to rotate. The central gear 538 drives the two racks 539 meshed with it to move relative to each other. The two racks 539 drive the dynamic balance counterweight 532 and the common rotation shaft connection block 533 connected to them to move relative to the motor shaft of the common rotation motor 51 as the center and move the same distance. The common rotation shaft connection block 533 drives the common rotation shaft 52 connected to it to move, so that an eccentricity is generated between the common rotation shaft 52 and the motor shaft of the common rotation motor 51; at the same time, the dynamic balance counterweight 532 is used to balance the eccentric mass generated after the movement of the common rotation shaft connection block 533 and the common rotation shaft 52, and the problem of dynamic imbalance caused by uneven mass is eliminated. That is to say, the eccentricity adjustment assembly 53 in this embodiment can not only realize the adjustment of the eccentricity, but also play a role in evenly distributing the mass of the polishing shaft common rotation mechanism 5, avoiding the problem of dynamic imbalance caused by the common rotation of the common rotation shaft 52.In addition, this embodiment further includes an eccentricity calibration scale 54 and a pointer 55 for measuring the eccentricity. The eccentricity calibration scale 54 is installed on the transmission case 56, and the pointer 55 is installed on the support housing 3 and points to the eccentricity calibration scale 54. Before the polishing device polishes the surface of the workpiece, the polishing actuator 4, the eccentricity adjustment component 53 in the polishing shaft revolution mechanism, and the polishing shaft rotation mechanism 6 are all in the initial state. At this time, the pointer 55 points to the 0 point of the eccentricity calibration scale 54. At the same time, the adjustment knob 534 is exactly opposite to the opening formed on the support housing 3. A wrench can be used to screw the adjustment knob 534. As the adjustment knob 534 rotates, the common rotation shaft 52 moves driven by the common rotation shaft connection block 533. The common rotation shaft 52 drives the transmission case 56 to move, and the eccentricity calibration scale 54 moves with the transmission case 56. The pointer 55 and the eccentricity calibration scale 54 move relatively. At this time, the value pointed to by the pointer 55 is the eccentricity. The adjustable range of the eccentricity in this embodiment is 0 - 15 mm. Before polishing, a suitable eccentricity is selected according to the diameter of the polishing head 41 and the size of the processed surface type of the workpiece through computer simulation or preliminary experiment, so that the removal function is close to the Gaussian type. The eccentricity adjustment component 53 is provided with a locking screw. The pre-tightening force of the adjustment screw prevents the eccentricity from changing during the rotation process and at the same time ensures that the torque for rotating the knob is moderate.

[0041] See Figure 3 , polishing liquid also needs to be sprayed onto the surface of the workpiece and the polishing head 41 during the processing. If the polishing liquid is sprayed onto the workpiece from one side of the polishing head 41, it will cause uneven spraying of the polishing liquid, aggravate the wear of the polishing pad, and affect the machining accuracy of the workpiece surface. Therefore, the center liquid supply method is generally adopted at present. If the polishing shaft 42 is directly connected to the common rotation shaft 52, it is impossible to realize the center passage of the polishing liquid.

[0042] Accordingly, the polishing shaft revolution mechanism described in this embodiment further includes a transmission box 56 and a cross guide rail 57. An opening is provided on the side surface of the support housing 3. One end of the transmission box 56 passes through the opening on the side surface of the support housing 3 and is inserted into the support housing 3. The revolution shaft 52 is inserted on the transmission box 56 through a bearing and drives the transmission box 56 to move along with the revolution shaft 52. The cross guide rail 57 is installed inside the support housing 3 and is connected to the bottom of the transmission box 56 to limit the movement of the transmission box 56. The polishing shaft 42 is a spline shaft with a central through hole. The polishing shaft 42 is connected to the end of the transmission box 56 outside the support housing 3 through the flange sleeve of the spline nut 47 and moves along with the transmission box 56. Since there are balls between the spline sleeve and the flange sleeve of the spline nut 47, it will not affect the rotation and axial movement of the polishing shaft 42. During the rotation of the revolution motor 51 in this embodiment, the revolution shaft 52 revolves around the motor shaft of the revolution motor 51 with a set eccentricity. The revolution shaft 52 transmits the revolution movement to the transmission box 56. Since the revolution shaft 52 is rotationally connected to the transmission box 56, the transmission box 56 decomposes the revolution circular movement into horizontal movements in two directions on a plane under the limitation of the cross guide rail 57, and makes the transmission box 56 perform a small-range revolution movement. The transmission box 56 drives the polishing shaft 42 connected to it to revolve around the polishing point on the workpiece surface. In this embodiment, through the design of the transmission box 56 and the cross guide rail 57, the separate design of the polishing shaft 42 and the revolution shaft 52 and the transmission of the revolution movement are realized. The polishing liquid can be fed into the central through hole of the polishing shaft 42 to ensure the uniform spraying of the polishing liquid between the polishing head 41 and the workpiece surface.

[0043] See Figure 7 , since the polishing shaft 42 rotates both revolutionally and rotationally, when the pre-prepared polishing liquid is pressed into the polishing shaft 42 through an external centrifugal pump by a liquid hose, the connection point between the liquid hose and the polishing shaft 42 will become entangled, resulting in the inability to supply liquid. Accordingly, the polishing execution mechanism 4 in this embodiment further includes a rotary joint 43 for connecting the liquid hose. The rotary joint 43 is installed at the top end of the polishing shaft 42 and can rotate. Specifically, the rotary joint 43 is provided with a rotor and a stator. The external hose is connected to the stator of the rotary joint 43, and the polishing shaft 42 is connected to the rotor of the rotary joint 43. When the polishing shaft 42 rotates, the rotary joint 43 only revolves with the polishing shaft 42 without rotating itself under the cooperation of the rotor and the stator, thus avoiding the entanglement problem between the liquid hose and the polishing shaft 42. The polishing liquid flows through the rotary joint 43 and the liquid supply channel of the polishing shaft 42 in sequence, and finally a fixed amount of polishing liquid is stably output from the central hole of the polishing head 41, keeping the removal function stable and realizing the polishing of the workpiece surface. In addition, the vulnerable parts such as the rotary joint 43 are arranged outside the polishing shaft 42, which is convenient for maintenance and replacement, and is not easily damaged by the cylinder in case of liquid leakage and other situations.

[0044] See Figure 7, the contact pressure between the polishing head 41 and the workpiece surface affects the stability of the removal function of the workpiece surface. Although the robotic arm can drive the polishing head 41 to contact and press the workpiece surface, the robotic arm cannot achieve precise adjustment of the contact pressure, which affects the machining accuracy of the workpiece surface.

[0045] Therefore, the polishing actuator 4 of this embodiment further includes a pressure regulating cylinder 44, a pressure transmission rod 45, and a pressure sensor 46 for adjusting the contact pressure between the polishing head 41 and the workpiece surface. The pressure regulating cylinder 44 is arranged in parallel on one side of the polishing shaft 42, and the cylinder block of the pressure regulating cylinder 44 is installed on the transmission case 56; one end of the pressure transmission rod 45 is sleeved on the polishing shaft 42 through two thrust ball bearings and can drive the polishing shaft 42 to move up and down. The other end of the pressure transmission rod 45 is connected to the telescopic rod of the pressure regulating cylinder 44 and moves up and down with the telescopic rod. The pressure sensor 46 is installed between the pressure transmission rod 45 and the polishing shaft 42, and is installed at a position on the polishing shaft 42 close to the polishing head 41. When the pressure transmission rod 45 moves up and down with the telescopic rod, the pressure transmission rod 45 drives the polishing shaft 42 to move up and down. The polishing shaft 42 drives the polishing head 41 to press the workpiece surface. The pressure sensor 46 measures the contact pressure between the polishing head 41 and the workpiece surface, and feeds back the pressure information to the PLC. By adjusting the external solenoid valve to control the cylinder pressure output, closed-loop control is achieved, making the normal contact force constant and obtaining a more stable material removal function. It should be noted that the polishing shaft 42 adopts a spline shaft structure, and its self-rotation torque is transmitted to the female rotary spline nut through balls and raceways. At the same time, the polishing shaft 42 can float up and down along the axial direction of the spline nut during the polishing process. In this embodiment, the pressure regulating cylinder 44 adopts a low-friction cylinder to adjust the pressure between the polishing head 41 and the workpiece surface, and the maximum stroke of the low-friction cylinder is 30 mm. Before polishing, the polishing pressure is preset, the pressure sensor 46 is calibrated to remove weight, and the cylinder air pressure corresponding to the specified pressure is set at the same time; then the robotic arm is controlled to press the polishing head 41 vertically against the workpiece surface. Cooperating with the stable movement of the polishing shaft revolution mechanism 5 and the polishing shaft rotation mechanism 6, the tremor of the overall polishing equipment is reduced, ensuring that the numerical fluctuation of the pressure sensor 46 is small. And because the pressure sensor 46 is arranged between the polishing head 41 and the pressure transmission rod 45, it is ensured that the pressure sensor 46 is closer to the polishing head 41 and will not be interfered by other moving parts, ensuring the accuracy of force measurement. Furthermore, the workpiece surface is machined under a constant pressure with the polishing head 41, improving the machining accuracy of the workpiece surface.

[0046] The working process of the present invention is further described below to further demonstrate the working principle and advantages of the present invention:

[0047] S1, Installation of the polishing equipment: Fix the polishing equipment on the end flange of the robot through the connecting flange 1 of the robotic arm. Connect the liquid hose connected to the polishing liquid circulation system to the rotary joint 43 at the top of the polishing shaft 42, and connect the pneumatic output system to the pressure regulating cylinder 44;

[0048] S2, Adjustment of the position between the polishing equipment and the workpiece: Fix the polishing workpiece on the polishing table. The robotic arm moves the polishing equipment to the polishing position of the workpiece and makes the lower surface of the polishing head 41 parallel to the surface of the workpiece;

[0049] S3, Adjustment of the contact pressure: Preset the polishing pressure, perform zeroing calibration on the pressure sensor 46, and at the same time set the cylinder air pressure corresponding to the specified pressure.

[0050] S4, Eccentricity adjustment: Insert a hex wrench into the reserved hole of the support housing 3 and turn the adjustment knob 534. The driving bevel gear 535 on the adjustment knob 534 drives the driven bevel gear 536 and the central connecting shaft 537 connected to the driven bevel gear 536 to rotate. The central connecting shaft 537 drives the central gear 538 to rotate. The central gear 538 drives the two racks 539 meshing with it to move relatively. The two racks 539 drive the dynamic balance counterweight 532 and the common rotating shaft connecting block 533 connected to them to move relatively around the motor shaft of the rotation motor 51; The common rotating shaft connecting block 533 drives the common rotating shaft 52 connected to it to move. The common rotating shaft 52 drives the transmission box 56 to move. The eccentricity calibration scale 54 moves with the transmission box 56. The pointer 55 moves relative to the eccentricity calibration scale 54. At this time, the index pointed to by the pointer 55 is the eccentricity.

[0051] S5, Workpiece polishing: Control the centrifugal pump in the polishing liquid circulation system to press the polishing liquid with a constant pressure and flow rate into the rotary joint 43, and finally flow out from the central hole of the polishing head 41 to the surface of the workpiece. Use the pneumatic output system to output compressed air with a constant air pressure into the low-friction cylinder block, so that the piston rod extends and drives the spline shaft to move downward until the pressure value measured by the pressure sensor 46 is the preset polishing pressure.

[0052] Start the revolution motor 51 and the rotation motor 61. The revolution shaft 52 revolves around the motor shaft of the revolution motor 51 with a set eccentricity. The revolution shaft 52 transmits the revolution motion to the transmission box 56. The transmission box 56 decomposes the revolution circular motion into horizontal motions in two directions on a plane under the limitation of the cross guide rail 57, and makes the transmission box 56 perform a small-range revolution motion. The transmission box 56 drives the polishing shaft 42 connected thereto to revolve around the polishing point on the surface of the workpiece. At the same time, the rotation motor 61 drives the rotation shaft 62 to rotate. The driving wheel 63 rotates with the rotation shaft 62. The torque of the driving wheel 63 is transmitted to the driven wheel 64 via the transmission belt 65. The driven wheel 64 drives the polishing shaft 42 to rotate; the center distance between the polishing shaft 42 and the rotation shaft 62 changes; when the center distance between the rotation shaft 62 and the polishing shaft 42 decreases, the tension spring 665 pushes the tension pulley 663 to move toward the transmission belt 65 side and always presses the transmission belt 65, and the transmission belt 65 is tensioned; when the center distance between the rotation shaft 62 and the polishing shaft 42 increases, the transmission belt 65 pushes the tension pulley 663 to move and presses the tension spring 665, and the tension spring 665 is compressed and stores a certain amount of elastic force. No matter how the center distance between the rotation shaft 62 and the polishing shaft 42 changes, the transmission belt 65 is always in a tensioned state, so that the torque of the rotation of the motor shaft of the rotation motor 61 can be stably transmitted to the polishing shaft 42, ensuring the stability during the rotation of the polishing shaft 42 and improving the polishing accuracy of the workpiece surface.

[0053] Set process parameters according to the processing technology, revolution speed 120 rmp / min, rotation speed 600 rmp / min, speed ratio 0.2, eccentricity e of 10 mm, diameter of the polishing head 41 of 30 mm, air pressure of 0.1 MPa, liquid supply pressure of 0.5 MPa, select cerium oxide polishing liquid with a diameter of 3 microns, polishing time of 1 h, and specify the polishing trajectory to calculate the dwell time to generate a processing program and import it into the robot system to perform deterministic polishing on the workpiece surface.

[0054] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not deviate from the spirit and scope of the present invention as defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A polishing device for the surface of an optical element, comprising a polishing execution mechanism, a polishing shaft revolution mechanism, and a polishing shaft rotation mechanism; the polishing execution mechanism includes a polishing head and a polishing shaft, the power output end of the polishing shaft revolution mechanism is connected to the polishing shaft and drives the polishing shaft to revolve; the power output end of the polishing shaft rotation mechanism is connected to the polishing shaft and drives the polishing shaft to rotate; the polishing head is connected to the polishing shaft and rotates and revolves with the polishing shaft; it is characterized in that, The polishing shaft self-rotation mechanism includes a self-rotation motor, a driving wheel, a driven wheel, a transmission belt, and a belt tensioning assembly. The driving wheel is connected to the motor shaft of the self-rotation motor and rotates with the motor shaft. The driven wheel is sleeved on the polishing shaft and drives the polishing shaft to rotate. The transmission belt is sleeved on the driving wheel and the driven wheel. The belt tensioning assembly contacts and tensions the transmission belt. When the polishing shaft revolution mechanism and the polishing shaft self-rotation mechanism drive the polishing shaft to perform revolution and self-rotation movements, as the center distance between the polishing shaft and the motor shaft of the self-rotation motor changes, the belt tensioning assembly contacts and tensions the transmission belt, so that the torque of the motor shaft of the self-rotation motor is stably transmitted to the polishing shaft; The belt tensioning assembly includes a guiding shaft, a tensioning wheel, and a tensioning spring. The guiding shaft is fixed on one side of the transmission belt. The tensioning wheel is connected to the guiding shaft and can move axially along the guiding shaft. The tensioning spring is sleeved on the guiding shaft and presses the tensioning wheel. When the center distance between the motor shaft of the self-rotation motor and the polishing shaft changes, the tensioning spring presses the tensioning wheel, so that the tensioning wheel presses and keeps the transmission belt tensioned; The polishing shaft revolution mechanism includes a revolution motor, a revolution shaft, and an eccentricity adjustment assembly. The eccentricity adjustment assembly connects the motor shaft of the revolution motor and the revolution shaft. When the eccentricity adjustment assembly adjusts the eccentricity between the motor shaft of the revolution motor and the revolution shaft, the mass of the polishing shaft revolution mechanism is symmetrically distributed with the motor shaft of the revolution motor as the center, so as to ensure the dynamic balance during the movement of the polishing shaft revolution mechanism; The eccentricity adjustment assembly includes a dynamic balance counterweight, a revolution shaft connecting block, a central gear, and two racks. The revolution shaft is connected to the revolution shaft connecting block and moves with the revolution shaft connecting block. Each of the dynamic balance counterweight and the revolution shaft connecting block is connected to a rack, and the two racks are engaged with the central gear. When the central gear rotates, the two racks drive the connected dynamic balance counterweight and revolution shaft connecting block to move relative to each other with the motor shaft of the revolution motor as the center, an eccentricity is generated between the revolution shaft and the motor shaft of the revolution motor, and at the same time, the mass of the dynamic balance counterweight and the mass of the revolution shaft connecting block and the revolution shaft are symmetrically distributed with the motor shaft of the revolution motor as the center; The polishing shaft revolution mechanism further includes a transmission box and a cross guide rail. The transmission box is sleeved outside the revolution shaft and moves with the revolution shaft. The cross guide rail is connected to the transmission box and limits the movement of the transmission box. The polishing shaft is connected to the transmission box and moves with the transmission box. When the revolution shaft revolves around the motor shaft of the revolution motor, the transmission box makes a revolution movement under the limitation of the cross guide rail, so that the polishing shaft makes a revolution movement around the polishing point on the surface of the workpiece.

2. The polishing device for the surface of an optical element according to claim 1, characterized in that, The eccentricity adjustment assembly further includes an eccentricity calibration scale and a pointer for measuring the eccentricity. The eccentricity calibration scale is installed on the transmission box, and the pointer is installed above the eccentricity calibration scale and points to the eccentricity calibration scale. When adjusting the eccentricity, the transmission box moves with the revolution shaft, and a displacement is generated between the eccentricity calibration scale and the pointer to realize the measurement of the eccentricity.

3. A polishing device for the surface of an optical element according to claim 1, characterized in that, The polishing execution mechanism further includes a rotary joint. The rotary joint is installed at the top of the polishing shaft and can rotate. The rotary joint and the polishing shaft are both provided with liquid supply channels and are communicated with each other. The polishing head is provided with a central hole and is communicated with the liquid supply channel of the polishing shaft.

4. A polishing device for the surface of an optical element according to claim 1, characterized in that, The polishing actuator further includes a pressure regulating cylinder, a pressure transmission rod, and a pressure sensor for adjusting the contact pressure between the polishing grinding head and the workpiece surface. The pressure regulating cylinder is arranged on one side of the polishing shaft. The cylinder block of the pressure regulating cylinder is installed on the transmission box. The pressure transmission rod connects the polishing shaft and the telescopic rod of the pressure regulating cylinder. The pressure sensor is installed between the pressure transmission rod and the polishing shaft. When the pressure transmission rod moves downward with the telescopic rod, the pressure transmission rod drives the polishing grinding head to move downward and contact the workpiece surface, and the air pressure of the pressure regulating cylinder is adjusted to change the contact pressure between the polishing grinding head and the workpiece surface.

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