Polishing equipment for surface of optical element

Abstract

The invention discloses polishing equipment for the surface of an optical element, and relates to the field of optical ultra-precision machining. The invention aims to solve the problem that the polishing precision of the surface of an optical element is affected due to unstable movement of a polishing grinding head in the rotation process because a polishing shaft does revolution motion while performing rotation motion. The polishing device comprises a polishing grinding head, a polishing shaft, a polishing shaft revolution mechanism and a polishing shaft rotation mechanism. The power output end of the polishing shaft revolution mechanism is connected with the polishing shaft and drives the polishing shaft to revolve; the polishing shaft autorotation mechanism adopts a synchronous belt group to drive a polishing shaft to autorotate, and a transmission belt is tensioned by a belt tensioning assembly; the polishing grinding head is connected to the polishing shaft and rotates and revolves along with the polishing shaft; when the polishing shaft revolution mechanism and the polishing shaft rotation mechanism drive the polishing shaft to do revolution and rotation motion, along with the change of the center distance between the polishing shaft and the motor shaft of the rotation motor, the belt tensioning assembly makes contact with and tensions the transmission belt, so that the torque of the motor shaft of the rotation motor is stably transmitted to the polishing shaft. The polishing device is used for polishing optical elements.

Description

Technical Field

[0001] The invention relates to the field of optical ultra-precision machining, and in particular 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, large-aperture optical components. Therefore, various ultra-precision processing technologies are also constantly 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 components. This polishing process allows the small tool head to perform both rotation and revolution on the surface of the optical component, that is, the polishing actuator needs to ensure that the small tool head rotates during the polishing process while also using eccentric motion of different distances around a certain axis, thereby forming a Gaussian removal function on the surface of the optical component, thereby improving the processing accuracy of the workpiece surface. But at the same time, in order to meet the above-mentioned motion state, this polishing process uses flexible torque transmission elements such as soft shafts and telescopic universal joints to realize the transmission of rotation torque, such as the "A Rigid Eccentric Transmission Rotational Air Pressure Force CNC Polishing Device" disclosed in Publication No. CN102962764B. The flexible torque transmission element will cause the small tool head to move unsteadily during the rotation process, which still affects the polishing accuracy of the optical component surface. 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, as the center distance between the polishing shaft and the motor shaft of the rotating motor changes, the belt tensioning assembly is used to always tension the transmission belt so that the torque of the motor shaft of the rotating motor can be stably transmitted 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 comprises a polishing actuator, a polishing shaft revolution mechanism and a polishing shaft self-rotation mechanism; the polishing actuator comprises a polishing grinding 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 self-rotation mechanism is connected to the polishing shaft and drives the polishing shaft to rotate; the polishing grinding head is connected to the polishing shaft and rotates and revolves with the polishing shaft; the polishing shaft self-rotation mechanism comprises 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, and 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 revolve and rotate, 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.

[0007] Furthermore, the belt tensioning assembly includes a guide shaft, a tensioning wheel and a tensioning 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 tensioning spring is sleeved on the guide shaft and squeezes the tensioning wheel; when the center distance between the motor shaft of the rotating motor and the polishing shaft changes, the tensioning spring squeezes the tensioning wheel so that the tensioning wheel squeezes and keeps the transmission belt tensioned.

[0008] Furthermore, the polishing shaft revolution mechanism includes a revolution motor, a revolution shaft and an eccentricity adjustment component; the eccentricity adjustment component connects the motor shaft of the revolution motor and the revolution shaft. When the eccentricity adjustment component 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 to ensure the dynamic balance of the polishing shaft revolution mechanism during movement.

[0009] Furthermore, the eccentricity adjustment assembly includes a dynamic balancing weight, a revolving shaft connecting block, a center gear and two racks; the revolving shaft is connected to the revolving shaft connecting block and moves with the revolving shaft connecting block; the dynamic balancing weight and the revolving shaft connecting block are each connected to a rack, and the two racks are meshed with the center gear; when the center gear rotates, the two racks drive the respectively connected dynamic balancing weight and the revolving shaft connecting block to move relative to each other with the motor shaft of the revolving motor as the center, and an eccentricity is generated between the revolving shaft and the motor shaft of the revolving motor, and at the same time, the mass of the dynamic balancing weight, the revolving shaft connecting block and the mass of the revolving shaft are symmetrically distributed with the motor shaft of the revolving motor as the center.

[0010] Furthermore, the polishing shaft revolution mechanism also 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 revolves under the limitation of the cross guide rail, so that the polishing shaft revolves around the polishing point on the workpiece surface.

[0011] Furthermore, the eccentricity adjustment assembly also includes an eccentricity calibration ruler and a pointer for measuring the eccentricity. The eccentricity calibration ruler is installed on the transmission box, and the pointer is installed above the eccentricity calibration ruler and points to the eccentricity calibration ruler. When adjusting the eccentricity, the transmission box moves with the orbital axis, and displacement occurs between the eccentricity calibration ruler and the pointer to realize the measurement of the eccentricity.

[0012] Furthermore, the polishing actuator also includes a rotary joint, which is installed on 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 connected to each other. The polishing grinding head is provided with a center hole and is connected to the liquid supply channel of the polishing shaft.

[0013] Furthermore, the polishing actuator also 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 body 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, and 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 adjusts the air pressure of the pressure regulating cylinder to change the contact pressure between the polishing grinding head and the workpiece surface.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The polishing shaft self-rotation mechanism of the present invention adopts a synchronous belt group to realize the transmission of rigid torque over a long distance. The self-rotation motor is separated from the polishing shaft, thereby avoiding the problem of increased rotational inertia caused by the self-rotation motor performing orbital motion with the polishing shaft. At the same time, when the polishing shaft orbital mechanism and the polishing shaft self-rotation mechanism drive the polishing shaft to perform orbital and self-rotation motions, as the center distance between the polishing shaft and the motor shaft of the self-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 self-rotation motor can be smoothly transmitted to the polishing shaft, thereby ensuring the stability of the polishing shaft during self-rotation and improving the polishing accuracy of the workpiece surface.

[0016] 2. The eccentricity adjustment assembly in the present invention utilizes a drive method of gears and racks, so that the two racks respectively drive the respectively connected dynamic balancing weights and the orbital shaft connecting block to move relative to and the same distance with the motor shaft of the orbital motor as the center, and the orbital shaft connecting block drives the orbital shaft connected to it to move, so that an eccentricity is generated between the orbital shaft and the motor shaft of the orbital motor; at the same time, the dynamic balancing weight is utilized to balance the eccentric mass generated by the orbital shaft connecting block and the orbital shaft after movement, thereby eliminating the problem of dynamic imbalance caused by uneven mass.

[0017] 3. The polishing shaft revolution mechanism of 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 transmission box revolution into linear motion in two directions in the 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 separation design of the polishing shaft and the revolution shaft and the transmission of the revolution motion, but also makes the movement of the polishing actuator more stable, reduces the vibration of the polishing actuator and the pressure sensor, and improves the polishing accuracy of the optical element surface.

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

[0019] 5. The present invention utilizes a low-friction cylinder to adjust the contact pressure between the polishing grinding head and the workpiece surface, measures the contact pressure through a pressure sensor and implements force feedback to control the cylinder pressure output, implements closed-loop control, makes the normal contact pressure on the workpiece surface constant, and obtains a more stable removal function. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0023] Figure 3 This is a cross-sectional view of the interior of the polishing equipment.

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

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

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

[0027] Figure 7 for Figure 3 A partial enlarged view of point A in the middle.

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

[0029] Description of reference numerals:

[0030] 1-Robotic arm connecting flange; 2-Flange support frame; 3-Support shell;

[0031] 4-polishing actuator, 41-polishing grinding head, 42-polishing shaft, 43-rotating joint, 44-pressure regulating cylinder, 45-pressure transmission rod, 46-pressure sensor, 47-spline nut;

[0032] 5-polishing shaft revolution mechanism, 51-revolution motor, 52-revolution shaft, 53-eccentricity adjustment assembly, 531-housing, 532-dynamic balancing weight, 533-revolution shaft connection block, 534-adjustment knob, 535-driving bevel gear, 536-driven bevel gear, 537-center connection shaft, 538-center gear, 539-rack, 54-eccentricity calibration ruler, 55-pointer, 56-transmission box, 57-cross guide;

[0033] 6-polishing shaft rotation mechanism, 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 axle, 665-tensioning spring. DETAILED DESCRIPTION

[0034] In order to make the purpose, 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 performs planetary motion around a certain point on the workpiece, the removal function can be made to have a Gaussian shape, thereby improving the machining accuracy of the workpiece surface. The prior art generally directly connects the self-rotating motor to the polishing shaft to drive the polishing head to rotate, but the self-rotating motor will perform orbital motion with the polishing shaft, resulting in an increase in the mass of the driven orbital part, which greatly increases the moment of inertia, thereby increasing the vibration amplitude of the polishing shaft and the polishing head, making the material removal unstable, and affecting the machining accuracy of the workpiece surface. There are also some technologies that separate the self-rotating motor from the polishing shaft, but all use flexible torque transmission elements such as soft shafts and telescopic universal joints to achieve the transmission of the self-rotation torque. This setting will cause the torque transmission to be unstable, which in turn causes the polishing head to move unsteadily during the self-rotation process, still affecting the polishing accuracy of the optical element surface.

[0036] Hence, see Figures 1 to 8, this embodiment provides a polishing device for the surface of an optical element, comprising a mechanical arm connecting flange 1, a flange support frame 2, a support shell 3, a polishing actuator 4, a polishing shaft revolution mechanism 5 for the revolution of the polishing shaft, and a polishing shaft self-rotation mechanism 6 for the self-rotation of the polishing shaft 42; the polishing device is connected to the mechanical arm via the mechanical arm connecting flange 1 and moves with the mechanical arm. The flange support frame 2 connects the mechanical arm connecting flange 1 and the support shell 3. The polishing shaft revolution mechanism 5 and the polishing shaft self-rotation mechanism 6 are installed on the support shell 3 and supported. The polishing actuator 4 comprises a polishing grinding head 41 and a polishing shaft 42, the power output end of the polishing shaft revolution mechanism 5 is connected to the polishing shaft 42 and drives the polishing shaft 42 to perform revolution motion; the power output end of the polishing shaft self-rotation mechanism 6 is connected to the polishing shaft 42 and drives the polishing shaft 42 to perform self-rotation motion. The polishing grinding head 41 is connected to the bottom end of the polishing shaft 42 and performs self-rotation and revolution motion with the polishing shaft 42. Specifically, the polishing shaft rotation mechanism 6 includes a rotation motor 61, a rotation shaft 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 supporting shell 3. The top end of the rotation shaft 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 shaft 62 is connected to the supporting shell 3 through a bearing and can rotate; the driving wheel 63 is sleeved on the outside of the rotation shaft 62 and is key-connected to the rotation shaft 62 to realize torque transmission; the polishing shaft 42 is also sleeved with a female rotating spline nut 47, the spline nut 47 is key-connected to the polishing shaft 42, and the driven wheel 64 is sleeved on the polishing shaft 42 and 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 self-rotating motor 61 is turned on, the self-rotating motor 61 drives the self-rotating shaft 62 to rotate, the driving wheel 63 rotates with the self-rotating shaft 62, and the torque of the driving wheel 63 is transmitted to the driven wheel 64 via the transmission belt 65, and the driven wheel 64 drives the polishing shaft 42 to rotate through the spline nut 47; at the same time, the polishing shaft revolution mechanism 5 drives the polishing shaft 42 to perform revolution motion, and the center distance between the polishing shaft 42 and the self-rotating shaft 62 changes, and the belt tensioning assembly 66 always contacts and tensions the transmission belt 65, so that the torque of the self-rotating shaft 62 can be stably transmitted to the polishing shaft 42. The polishing shaft self-rotating mechanism 6 of this embodiment adopts a synchronous belt group to realize the transmission of rigid torque over a long distance, and the self-rotating motor 61 is separated from the polishing shaft 42, so as to avoid the problem of increased rotational inertia caused by the self-rotating motor 61 performing revolution motion with the polishing shaft 42.In addition, since the length of the transmission belt 65 is fixed, when the polishing shaft 42 makes a small range of revolution, as the center distance between the polishing shaft 42 and the rotation 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, this embodiment uses the belt tensioning assembly 66 to always tension the transmission belt 65 so that the torque of the motor shaft of the rotation motor 61 can be smoothly transmitted to the polishing shaft 42, thereby ensuring the stability of the polishing shaft 42 during rotation and improving the polishing accuracy of the workpiece surface.

[0037] See also Figure 8 The belt tensioning assembly 66 in this embodiment 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 supporting shell 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 along the axial direction of the guide shaft 662, and the tensioning wheel 663 is sleeved on the other end of the wheel shaft 664 and can rotate. At the same time, the outer cylindrical 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 squeezes the wheel shaft 664. When the self-rotating shaft 62 is in contact with the polishing When the center distance between the shafts 42 decreases, the tensioning spring 665 pushes the tensioning wheel 663 to move toward the side of the transmission belt 65 and always squeezes the transmission belt 65, so that the transmission belt 65 is tensioned; when the center distance between the rotating shaft 62 and the polishing shaft 42 increases, the transmission belt 65 pushes the tensioning wheel 663 to move and squeezes the tensioning spring 665, and the tensioning spring 665 is compressed and stores a certain elastic force. That is to say, with the cooperation of the tensioning spring 665 and the tensioning wheel 663, no matter how the center moment between the rotating shaft 62 and the polishing shaft 42 changes, the transmission belt 65 is always in a tensioned state, so that the stable transmission of torque between the driving wheel 63 and the driven wheel 64 can be achieved.

[0038] See also Figures 2 to 5When facing different polishing workpieces, the revolution range of the polishing shaft 42 needs to be adjusted, so it is necessary to adjust the eccentricity of the revolution shaft 52 and the motor shaft of the revolution motor 51. At present, the adjustment of the eccentricity is generally achieved by using moving pairs such as screw nut pairs and sliding guides. This eccentricity adjustment structure will cause the overall mass distribution of the polishing shaft revolution mechanism to be uneven after the eccentricity is adjusted, causing dynamic imbalance of the revolution shaft. The dynamic imbalance of the revolution shaft will cause vibration of the robot arm and the actuator, resulting in unstable contact between the polishing grinding head and the workpiece, and the sensor measuring the contact force signal will also fluctuate, so that the accurate adjustment of the polishing force of the workpiece surface cannot be achieved, affecting the processing accuracy of the workpiece surface. Therefore, the dynamic imbalance problem of the revolution part will cause the material removal function to be unstable and bring about large processing errors. The dynamic imbalance of the rotor will cause the robot arm actuator to vibrate, resulting in unstable contact, problems with force measurement, and poor control of contact force, and then the material removal function will be unstable, affecting the processing 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, so as to ensure the dynamic balance of the polishing shaft revolution mechanism 5 during movement.

[0040] Specific, combined Figure 3 , Figure 4 and Figure 5The eccentricity adjustment assembly 53 in this embodiment includes a housing 531, a dynamic balancing weight 532, a revolution shaft connection block 533, an adjustment knob 534, an active 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 shell with an opening at the bottom, and the motor shaft of the revolution motor 51 is connected to the top of the housing 531 via a reducer and can drive the housing 531 to rotate; a balancing weight guide port and a reserved hole are provided on the side wall of the housing 531, and the balancing weight guide port and the reserved hole are arranged oppositely. The dynamic balancing weight 532 is a shell-like structure with an opening at the bottom, and a waist hole is provided on the top of the dynamic balancing weight 532. The dynamic balancing weight 532 is inserted into the housing 531 via the balancing weight guide port, and the dynamic balancing weight 532 can move along the balancing weight guide port. The revolution 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 center connecting shaft 537 passes through the waist hole at the top of the dynamic balancing weight 532 and is rotatably connected to the shell 531. The center gear 538 is connected to the other end of the center connecting shaft 537 and rotates with the center connecting shaft 537. The active bevel gear 535, the driven bevel gear 536, the center connecting shaft 537, the center gear 538 and the two racks 539 are all in the dynamic balancing weight 532. One end of the adjusting knob 534 passes through the reserved hole on the shell 531 and is connected to the active bevel gear 535. The other end of the adjusting knob 534 is a hexagonal knob. A hexagonal wrench is used to reach into the reserved hole to adjust the eccentricity, which is easy to operate. The driven bevel gear 536 is sleeved on the central connecting shaft 537 and meshed with the driving bevel gear 535; the dynamic balancing weight block 532 and the revolving shaft connecting block 533 are each connected to a rack 539, and the two racks 539 are meshed with the central gear 538; the revolving shaft 52 is connected to the revolving shaft connecting block 533 and moves with the revolving shaft connecting block 533. In this embodiment, the adjusting knob 534 is manually rotated, the active bevel gear 535 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 relative to each other, the two racks 539 drive the respectively connected dynamic balancing weights 532 and the revolving shaft connecting block 533 to move relative to each other and move the same distance with the motor shaft of the revolving motor 51 as the center, the revolving shaft connecting block 533 drives the revolving shaft 52 connected to it to move, so that the revolving shaft 52 and the motor shaft of the revolving motor 51 have an eccentricity; at the same time, the dynamic balancing weight 532 is used to balance the eccentric mass generated by the revolving shaft connecting block 533 and the revolving shaft 52 after the movement, so as to eliminate the problem of dynamic imbalance caused by uneven mass. That is to say, the eccentricity adjustment component 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 revolution mechanism 5, thereby avoiding the problem of dynamic imbalance caused by the revolution shaft 52 during the revolution process.In addition, this embodiment also includes an eccentricity calibration ruler 54 and a pointer 55 for measuring eccentricity. The eccentricity calibration ruler 54 is installed on the transmission box 56, and the pointer 55 is installed on the support shell 3 and points to the eccentricity calibration ruler 54. Before the polishing equipment 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 ruler 54. At the same time, the adjustment knob 534 is opposite to the opening opened on the support shell 3. The adjustment knob 534 can be turned with a wrench. As the adjustment knob 534 rotates, the revolution shaft 52 moves driven by the revolution shaft connecting block 533, and the revolution shaft 52 drives the transmission box 56 to move. The eccentricity calibration ruler 54 moves with the transmission box 56, and the pointer 55 moves relative to the eccentricity calibration ruler 54. At this time, the index pointed to by the pointer 55 is the eccentricity. The adjustable range of the eccentricity in this embodiment is 0-15mm. Before polishing, a suitable eccentricity is selected according to the diameter of the polishing grinding head 41 and the type and size of the workpiece processing surface through computer simulation or preliminary experiments, so that the removal function is close to a Gaussian type. The eccentricity adjustment component 53 is provided with a locking screw, and the pre-tightening force of the adjusting screw prevents the eccentricity from changing during rotation, while ensuring that the torque for rotating the knob is moderate.

[0041] See also Figure 3 During the machining process, the workpiece surface needs to spray polishing liquid onto the polishing head 41 and the workpiece surface. 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 central liquid supply method is generally adopted at this stage. If the polishing shaft 42 is directly connected to the revolution shaft 52, it is impossible to achieve the central supply of polishing liquid.

[0042] Therefore, the polishing shaft revolution mechanism described in this embodiment also includes a transmission box 56 and a cross guide 57. The side of the support shell 3 is provided with an opening. One end of the transmission box 56 passes through the opening of the side of the support shell 3 and is inserted into the support shell 3. The revolution shaft 52 is inserted into the transmission box 56 through a bearing and drives the transmission box 56 to move with the revolution shaft 52. The cross guide 57 is installed in the support shell 3 and 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 one end of the transmission box 56 outside the support shell 3 through the flange sleeve of the spline nut 47 and moves with the transmission box 56. Since a ball is provided between the spline sleeve and the flange sleeve of the spline nut 47, the rotation and axial movement of the polishing shaft 42 will not be affected. During the rotation of the revolving motor 51 in this embodiment, the revolving shaft 52 revolves around the motor shaft of the revolving motor 51 with a set eccentricity, and the revolving shaft 52 transmits the revolving motion to the transmission box 56. Since the revolving shaft 52 and the transmission box 56 are rotatably connected, the transmission box 56 decomposes the revolving circular motion into horizontal motion in two directions of the plane under the limit of the cross guide 57, and makes the transmission box 56 perform a small range of revolving motion, and the transmission box 56 drives the polishing shaft 42 connected thereto to perform revolving motion around the polishing point on the surface of the workpiece. In this embodiment, the separation design of the polishing shaft 42 and the revolving shaft 52 and the transmission of the revolving motion are realized through the design of the transmission box 56 and the cross guide 57. The polishing liquid can be supplied from the central through hole of the polishing shaft 42 to ensure the uniform spraying of the polishing liquid between the polishing grinding head 41 and the surface of the workpiece.

[0043] See also Figure 7 Since the polishing shaft 42 performs both revolution and rotation, when the polishing liquid prepared in advance is pressed into the polishing shaft 42 through the liquid hose by an external centrifugal pump, the connection point between the liquid hose and the polishing shaft 42 will be entangled, resulting in failure to supply liquid. Therefore, the polishing actuator 4 in this embodiment also includes a rotary joint 43 for connecting the liquid hose, and the rotary joint 43 is installed at the top 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 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 turn, and finally the central hole of the polishing grinding head 41 stably outputs a quantitative polishing liquid, keeps the removal function stable, and realizes the polishing of the workpiece surface. In addition, wearing parts such as the rotary joint 43 are arranged outside the polishing shaft 42, which is convenient for maintenance and replacement, and is not easy to damage the cylinder when leakage occurs.

[0044] See also Figure 7The 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 squeeze 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 also includes a pressure regulating cylinder 44, a pressure transmission rod 45 and a pressure sensor 46 for adjusting the contact pressure between the polishing grinding 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 body of the pressure regulating cylinder 44 is installed on the transmission box 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, and 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 on the polishing shaft 42 near the polishing grinding 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, and the polishing shaft 42 drives the polishing grinding head 41 to squeeze the workpiece surface. The pressure sensor 46 measures the contact pressure between the polishing grinding 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 to make the normal contact force constant and obtain a more stable material removal function. It should be noted that the polishing shaft 42 adopts a spline shaft structure, which transmits the rotation torque with the female rotating spline nut through balls and raceways. At the same time, during the polishing process, the polishing shaft 42 can float up and down along the axial direction of the spline nut. In this embodiment, the pressure regulating cylinder 44 adopts a low-friction cylinder to adjust the pressure between the polishing grinding head 41 and the workpiece surface, and the maximum stroke of the low-friction cylinder is 30mm. Before polishing, the polishing pressure is pre-set, the pressure sensor 46 is calibrated for deduplication, and the cylinder pressure corresponding to the specified pressure is set; then the robotic arm is controlled to press the polishing head 41 vertically against the workpiece surface, and the movement of the polishing axis revolution mechanism 5 and the polishing axis rotation mechanism 6 is stable, thereby reducing the vibration of the overall polishing equipment and ensuring that the value fluctuation of the pressure sensor 46 is small. In addition, since the pressure sensor 46 is arranged between the polishing head 41 and the pressure transmission rod 45, the pressure sensor 46 is closer to the polishing head 41 without being disturbed by other moving parts, thereby ensuring the accuracy of force measurement, thereby allowing the workpiece surface and the polishing head 41 to be processed under constant pressure, thereby improving the processing 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 flange plate at the end of the robot through the robot arm connecting flange 1, 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 air pressure output system to the pressure regulating cylinder 44;

[0048] S2, adjusting the position of the polishing device and the workpiece: fixing the polishing workpiece on the polishing workbench, the robot arm moves the polishing device to the polishing position of the workpiece, and makes the lower surface of the polishing grinding head 41 parallel to the surface of the workpiece;

[0049] S3, adjustment of contact pressure: pre-set the polishing pressure, perform de-weighting calibration on the pressure sensor 46, and set the cylinder pressure corresponding to the specified pressure.

[0050] S4, eccentricity adjustment: the hexagonal wrench is inserted into the reserved hole of the support shell 3 and the adjusting knob 534 is turned, the active bevel gear 535 on the adjusting 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 relative to each other, the two racks 539 drive the respectively connected dynamic balancing weight 532 and the revolution shaft connecting block 533 to move relative to each other with the motor shaft of the revolution motor 51 as the center; the revolution shaft connecting block 533 drives the revolution shaft 52 connected to it to move, the revolution shaft 52 drives the transmission box 56 to move, the eccentricity calibration ruler 54 moves with the transmission box 56, the pointer 55 moves relative to the eccentricity calibration ruler 54, and 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 pressurize the polishing liquid with constant pressure flow into the rotary joint 43, and finally flow out from the center hole of the polishing grinding head 41 to the surface of the workpiece, and use the air pressure output system to output compressed air with constant air pressure to the low-friction cylinder body, 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] The revolving motor 51 and the rotating motor 61 are started, and the revolving shaft 52 revolves around the motor shaft of the revolving motor 51 at a set eccentricity. The revolving shaft 52 transmits the revolving motion to the transmission box 56. The transmission box 56 decomposes the revolving circular motion into horizontal motion in two directions in the plane under the limitation of the cross guide rail 57, and makes the transmission box 56 revolve in a small range. The transmission box 56 drives the polishing shaft 42 connected to it to revolve around the polishing point on the surface of the workpiece. At the same time, the self-rotating motor 61 drives the self-rotating shaft 62 to rotate, and the driving wheel 63 rotates with the self-rotating shaft 62. The torque of the driving wheel 63 is transmitted to the driven wheel 64 via the transmission belt 65, and the driven wheel 64 drives the polishing shaft 42 to rotate; the center distance between the polishing shaft 42 and the self-rotating shaft 62 changes; 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 toward the transmission belt 65 side and always squeezes 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 squeezes the tensioning spring 665, and the tensioning spring 665 is compressed and stores a certain elastic force. No matter how the center moment between the self-rotating shaft 62 and the polishing shaft 42 changes, the transmission belt 65 is always in a tensioned state, 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 the rotation process and improving the polishing accuracy of the workpiece surface.

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

[0054] Although the present invention is 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. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A polishing device for the surface of an optical element, comprising a polishing actuator, a polishing shaft revolution mechanism and a polishing shaft rotation mechanism; the polishing actuator comprises a polishing grinding 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 grinding head is connected to the polishing shaft and rotates and revolves with the polishing shaft; characterized in that The polishing shaft rotation mechanism includes a self-rotating 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-rotating 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 rotation mechanism drive the polishing shaft to perform revolution and rotation, as the center distance between the polishing shaft and the motor shaft of the self-rotating motor changes, the belt tensioning assembly contacts and tensions the transmission belt, so that the torque of the motor shaft of the self-rotating motor can be stably transmitted to the polishing shaft.

2. A polishing device for the surface of an optical element according to claim 1, characterized in that: The belt tensioning assembly includes a guide shaft, a tensioning wheel and a tensioning 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 tensioning spring is sleeved on the guide shaft and squeezes the tensioning wheel. When the center distance between the motor shaft of the rotating motor and the polishing shaft changes, the tensioning spring squeezes the tensioning wheel so that the tensioning wheel squeezes and keeps the transmission belt tensioned.

3. A polishing device for the surface of an optical element according to claim 1, characterized in that: The polishing shaft revolution mechanism includes a revolution motor, a revolution shaft and an eccentricity adjustment component; the eccentricity adjustment component connects the motor shaft of the revolution motor and the revolution shaft. When the eccentricity adjustment component 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 to ensure the dynamic balance of the polishing shaft revolution mechanism during movement.

4. A polishing device for the surface of an optical element according to claim 3, characterized in that: The eccentricity adjustment assembly includes a dynamic balancing weight, a revolving shaft connecting block, a center gear and two racks; the revolving shaft is connected to the revolving shaft connecting block and moves with the revolving shaft connecting block; the dynamic balancing weight and the revolving shaft connecting block are each connected to a rack, and the two racks are meshed with the center gear; when the center gear rotates, the two racks drive the respectively connected dynamic balancing weight and the revolving shaft connecting block to move relative to each other with the motor shaft of the revolving motor as the center, and an eccentricity is generated between the revolving shaft and the motor shaft of the revolving motor, and at the same time, the mass of the dynamic balancing weight, the revolving shaft connecting block and the mass of the revolving shaft are symmetrically distributed with the motor shaft of the revolving motor as the center.

5. The polishing device for the surface of an optical element according to claim 3, characterized in that: The polishing shaft revolution mechanism also 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 revolves under the limit of the cross guide rail, so that the polishing shaft revolves around the polishing point on the surface of the workpiece.

6. A polishing device for the surface of an optical element according to claim 5, characterized in that: The eccentricity adjustment assembly also includes an eccentricity calibration ruler and a pointer for measuring the eccentricity. The eccentricity calibration ruler is installed on the transmission box, and the pointer is installed above the eccentricity calibration ruler and points to the eccentricity calibration ruler. When adjusting the eccentricity, the transmission box moves with the orbital axis, and displacement occurs between the eccentricity calibration ruler and the pointer to realize the measurement of the eccentricity.

7. A polishing device for the surface of an optical element according to claim 1, characterized in that: The polishing actuator also includes a rotary joint, which is installed on 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 connected. The polishing grinding head is provided with a center hole and is connected with the liquid supply channel of the polishing shaft.

8. The polishing device for the surface of an optical element according to claim 5, characterized in that: The polishing actuator also 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 body 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, and 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 adjusts the air pressure of the pressure regulating cylinder to change the contact pressure between the polishing grinding head and the workpiece surface.

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