Optical aspheric robot elliptical vibration polishing device and method

Abstract

The application belongs to the technical field of precision machining of optical elements, and relates to an optical aspheric surface robot elliptical vibration polishing device and method. The device comprises an elliptical vibration polishing assembly composed of a pressure adjusting cylinder, a motor, an electric slip ring and an ultrasonic vibration polishing unit. The motor spindle is in key connection with the ultrasonic vibration polishing unit through the electric slip ring. The ultrasonic vibration polishing unit comprises an outer shell and an ultrasonic elliptical vibrator coaxially fixed in the outer shell. The ultrasonic elliptical vibrator comprises an ultrasonic amplitude transformer, a sleeve and a clamping clamp arranged coaxially in sequence. The clamping clamp extends to the outside of the outer shell through the outer shell, and a polishing rod is clamped and fixed at the end of the clamping clamp. The pressure adjusting cylinder pushes the ultrasonic vibration polishing unit to realize soft contact with a workpiece. Meanwhile, the spindle of the motor drives the polishing rod to rotate, and the ultrasonic elliptical vibrator drives the polishing rod to make elliptical vibration through the ultrasonic amplitude transformer. The application improves the geometric precision of aspheric surface machining, greatly improves the polishing efficiency, and shortens the machining cycle.

Description

Technical Field

[0001] The present application belongs to the technical field of precision machining of optical elements, and more specifically, relates to an optical aspheric robot elliptical vibration polishing device and method. Background Art

[0002] Existing optical aspheric surface processing technologies include small grinding heads, air bags, magnetorheological fluid, ion beams, etc. Small grinding heads and air bag polishing control the amount of material removal by adjusting the dwell time and pressure, but the removal efficiency of small grinding heads is low, and the air bag has high requirements on the motion accuracy of the machine tool, which makes it difficult to control. The shaping accuracy range of magnetorheological fluid and ion beam polishing is narrow, and the equipment cost is high. In order to improve the polishing efficiency, some polishing devices combined with ultrasonic vibration technology have been proposed in recent years. For example, Chinese invention patent CN112775728A discloses an ultrasonic polishing device for use with a robot. This solution mainly relies on the shear and friction generated by torsional vibration to achieve the polishing effect. It is suitable for rough polishing of workpieces, and its torsional characteristics may leave specific tracks and scratches on the surface of the workpiece. Chinese invention patent CN104476378A discloses a single-excitation ultrasonic elliptical vibration polishing device. Although the device can produce an elliptical vibration polishing trajectory, due to structural limitations, the device cannot independently and flexibly control the vibration in two directions and can only be used at fixed frequency points. The frequency modulation is limited. Moreover, due to the limitations of the device structure, it can only be used for flat surface polishing and cannot be expanded to the field of complex curved surface polishing. Chinese invention patent CN105171537B discloses an ultrasonic vibration polishing grinding head device that can suppress the intermediate frequency error of optical components. In this technical solution, the vibration of the entire tool will inevitably aggravate the fatigue characteristics of the motor and transmission parts, seriously affecting the service life of the tool. Secondly, although the flexible hinge grinding head moves irregularly under vibration, it cannot effectively affect the intermediate frequency error left by the polishing tool under the fixed polishing trajectory. Moreover, due to the limitations of the grinding disc structure, it is not suitable for polishing complex curved surfaces. Chinese invention patent CN109571158A discloses a circumferentially driven ultrasonic vibration assisted polishing tool and Chinese invention patent CN109623509A discloses a centrally driven ultrasonic vibration assisted polishing tool, both of which convert displacement vibration into spatial multi-dimensional vibration by designing a spring damping rod, a ball head push rod, etc. at the end of the ultrasonic vibration standard tool handle. However, adding a complex device to the ultrasonic tool handle will introduce additional vibration nodes and reflection points, significantly reducing the vibration transmission efficiency. In addition, the complex structure will change the overall mass and stiffness distribution of the device, thereby affecting the resonant frequency. Such a structural design will greatly increase the difficulty of debugging and the stability of the device, which may affect the quality and efficiency of processing. Therefore, this method has not been widely used in the processing field.

[0003] In summary, how to greatly improve the polishing efficiency, shorten the processing cycle and reduce the production cost while ensuring the geometric accuracy of aspheric surface, and realize the batch production of optical aspheric surface is the problem that needs to be solved in the field of ultra-precision machining at present. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide an optical aspheric surface robot elliptical vibration polishing device and method, aiming to solve the problem of improving the polishing efficiency and quality of hard and brittle difficult-to-machine materials.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides an optical aspheric surface robot elliptical vibration polishing device, comprising an elliptical vibration polishing assembly, the elliptical vibration polishing assembly comprises a pressure regulating cylinder, a motor, an electric slip ring and an ultrasonic vibration polishing unit connected in series, the main shaft of the motor is connected with the ultrasonic vibration polishing unit through the electric slip ring; the ultrasonic vibration polishing unit comprises a housing and an ultrasonic elliptical vibration sub coaxially fixed in the housing; the ultrasonic elliptical vibration sub comprises an ultrasonic amplitude transformer, a sleeve and a clamping in series; the clamping extends to the outside of the housing, and the end of the clamping is fixed with a polishing head; the pressure regulating cylinder is used to push the ultrasonic vibration polishing unit to realize soft contact between the polishing head and the workpiece; the main shaft of the motor is used to drive the polishing head to rotate; the ultrasonic elliptical vibration sub is used to drive the polishing head to make elliptical vibration through the ultrasonic amplitude transformer.

[0006] Further, the material of the ultrasonic amplitude transformer is aluminum alloy or titanium alloy.

[0007] Further, the pressure regulating cylinder is a double-acting cylinder, and a proportional pressure valve is arranged on the pressure regulating cylinder, the proportional pressure valve is used to adjust the cylinder thrust.

[0008] Further, the cylinder push plate of the pressure regulating cylinder is connected with the output shaft of the motor.

[0009] Further, the housing is a hollow cylinder, the ultrasonic elliptical vibration sub further comprises a piezoelectric ceramic group and an end cover, the end cover, the piezoelectric ceramic group and the ultrasonic amplitude transformer are connected in series, the end cover and the ultrasonic amplitude transformer are respectively provided with radially symmetrical stationary point mounting holes, the housing is provided with stationary point support screw holes matched with the stationary point mounting holes, and the stationary point mounting holes and the stationary point support screw holes are connected through a screw rod.

[0010] Furthermore, the ultrasonic vibration polishing unit also includes an ultrasonic vibration controller, an ultrasonic power supply and a power amplifier group. The ultrasonic vibration controller is used to determine the resonant operating point of the ultrasonic vibration polishing unit and control the ultrasonic power supply to output an electrical signal of corresponding frequency for the power amplifier group; the power amplifier group is used to amplify the gain of the electrical signal and transmit it to the piezoelectric ceramic group, thereby driving the polishing rod to vibrate in an elliptical trajectory.

[0011] Furthermore, the robot elliptical vibration polishing device also includes an industrial robot and a polishing liquid supply module. The elliptical vibration polishing component is installed at the processing end of the industrial robot. The liquid outlet of the polishing liquid supply module is located above the polishing position and is used to supply polishing liquid during polishing.

[0012] According to a second aspect of the present application, a method for polishing using the aforementioned optical aspheric robot elliptical vibration polishing device is also disclosed, wherein the polishing is performed by traversing the surface of the workpiece according to a preset running trajectory of the polishing head, comprising:

[0013] S1 adjusts the cylinder thrust of the pressure regulating cylinder to balance the cylinder thrust with the gravity of the ultrasonic vibration polishing unit;

[0014] S2 continues to adjust the cylinder thrust of the pressure regulating cylinder to control the soft contact pressure between the polishing head and the workpiece;

[0015] S3 controls the motor rotation to drive the ultrasonic vibration polishing unit to rotate synchronously, and at the same time controls the ultrasonic elliptical vibrator to output a second-order longitudinal vibration signal and a fourth-order bending vibration signal with consistent resonant frequency to drive the polishing rod to perform elliptical vibration to achieve polishing of the workpiece.

[0016] Furthermore, before step S1, a fixed-point polishing method is used to obtain a removal function of the polishing head under a specific material and polishing environment; an interferometer is used to obtain the surface error data of the workpiece to be polished, and the removal function and surface error data of the workpiece to be polished are used to obtain the preset running trajectory of the polishing head, and according to the surface error data and curvature of the workpiece, the working parameters of the industrial robot and the corresponding polishing liquid flow rate are planned.

[0017] Furthermore, when the industrial robot controls the elliptical vibration polishing assembly to traverse the optical curved surface of the workpiece along the polishing trajectory, the normal line of the polishing head coincides with the normal line of the optical curved surface of the workpiece.

[0018] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0019] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0020] (1) The elliptical vibration polishing assembly of the present application has an optimized design for the connection structure at the end of the amplitude rod. The traditional cutting process is a process in which the diamond tool and the workpiece come into hard contact to remove material. The diamond tool of the cutting device is locked to the end of the amplitude rod by the upper fastening screw. The preload force, front angle and back angle position of the screw directly affect the elliptical vibration direction of the tool. In addition, the replacement of the tool requires re-frequency adjustment and precise position calibration. The vibration mode is greatly affected by the size of the tool. The tool is non-standard and customized, and the cost is high and the cycle is long. Polishing is a soft contact. The present application relies on a force control mechanism composed of a pressure regulating cylinder and a motor to press the polishing head against the surface of the workpiece to remove material by friction. The polishing head is connected to the end of the amplitude rod by a collet sleeve. The collet can adapt to polishing rods of different sizes and materials. It can also transmit the amplitude of the amplitude rod to the polishing head, and allows a certain error without precise adjustment. In this way, the device can adapt to standard polishing heads of different sizes, reducing the cost of use.

[0021] (2) In this application, considering that the polishing process is a soft contact process, the amplitude transformer is made of lighter aluminum alloy and titanium alloy to achieve the effect of amplitude amplification. Compared with the front cover of the traditional cutting device made of steel, which provides a certain degree of rigidity to the diamond tool during the hard-to-hard cutting process, but results in a smaller amplitude, the amplitude transformer made of aluminum alloy and titanium alloy amplifies the amplitude and is more suitable for polishing.

[0022] (3) Compared with a fixed cutting device, the present application adds a force control device and provides a degree of rotational freedom for the polishing head (i.e., the polishing rod). The additional rotation of the polishing head while vibrating can make the material removal more uniform, and obtain a more stable polishing removal function and material removal amount. In addition, through the added force control device, the contact force between the polishing head and the workpiece during the polishing process can be adjusted, thereby adjusting the processing removal amount.

[0023] (4) Compared with traditional diamond cutting devices, the present invention significantly improves processing quality and stability. Since the polishing head and the workpiece are in soft contact, the impact of node offset is minimal, so the elliptical amplitude of the device is more stable, which is more conducive to improving processing accuracy.

[0024] (5) The present application provides an optical aspheric elliptical ultrasonic vibration polishing method, which combines an elliptical ultrasonic vibration polishing device with a robot, which can not only realize flexible and adjustable multi-dimensional ultrasonic vibration, but also adapt to complex optical surfaces, further improve the polishing efficiency of optical surfaces based on hard and brittle materials, and greatly reduce the cost of polishing equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the overall assembly of the robot elliptical vibration polishing device provided in an embodiment of the present application;

[0026] Figure 2Schematic diagram of the structure of the elliptical vibration polishing device provided in an embodiment of the present application;

[0027] Figure 3 is a schematic cross-sectional view of an elliptical vibration polishing device provided in an embodiment of the present application;

[0028] Figure 4 This is a schematic diagram of the driving principle of the elliptical vibration polishing device provided in an embodiment of the present application;

[0029] Figure 5 2. It is a schematic structural diagram of an ultrasonic elliptical vibrator of an elliptical vibration polishing device provided in an embodiment of the present application;

[0030] Figure 6 This is a schematic diagram of the structural outline of the package shell of the elliptical vibration polishing device provided in an embodiment of the present application;

[0031] Figure 7 This is a test diagram of the vibration trajectory of the polishing head of the elliptical vibration polishing device provided in an embodiment of the present application;

[0032] Figure 8 This is a schematic diagram of the transducer vibration mode and nodes of the elliptical vibration polishing device provided in an embodiment of the present application.

[0033] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0034] 1-Elliptical vibration polishing assembly; 11-Ultrasonic vibration polishing unit, 111-Ultrasonic vibration controller; 112-Ultrasonic elliptical vibrator, 1121-End cap, 1122-Longitudinal vibration piezoelectric ceramic group, 1123-Bending vibration piezoelectric ceramic group, 1124-Ultrasonic amplitude transformer, 1125-Piezoelectric detection element, 1126-Sleeve, 1127-Clamp, 1128-Polishing head, 1129-Station support threaded hole, 1130-Station mounting hole; 113-Dual-channel ultrasonic power supply; 114-Power amplifier group; 115-Casing; 12-Electric slip ring; 13-Motor; 14-Pressure regulating cylinder; 15-Mounting flange; 16-Spindle; 21-Industrial robot; 22-Robot control system; 3-Polishing liquid supply module, 31-Polishing liquid barrel, 32-Peristaltic pump; 4-Polishing process software system; 5-Aspheric optical element to be polished. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0036] The term "and / or" as used herein describes an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " as used herein indicates that the related objects are in an "or" relationship, for example, A / B means either A or B.

[0037] The terms "first" and "second" in this specification and claims are used to distinguish different objects rather than to describe a specific order of objects. For example, "first response message" and "second response message" are used to distinguish different response messages rather than to describe a specific order of response messages.

[0038] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0039] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0040] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0041] This embodiment provides an optical aspheric robot elliptical vibration polishing device, including an elliptical vibration polishing component 1, an industrial robot 21 and a polishing liquid supply module 3. The elliptical vibration polishing component 1 is installed at the processing end of the industrial robot 21, and the liquid outlet end of the polishing liquid supply module 3 is located directly above the polishing position and is used to add polishing liquid during polishing.

[0042] Specifically, such as Figure 1 As shown, an industrial robot 21 is mounted on the polishing system base and is used to carry the elliptical vibration polishing assembly 1. As the elliptical vibration polishing assembly 1 traverses the optical surface along the polishing trajectory, the industrial robot, driven by the robot controller 22, moves along the polishing trajectory, with the normal of the polishing head in the elliptical vibration polishing assembly 1 coinciding with the normal of the optical surface. More specifically, the polishing process software system 4 is mounted on an external controller and is primarily used to generate the polishing trajectory. Its functions include importing surface error data, generating or importing removal functions, resident algorithms, and polishing trajectory calculation. It can also output NC files that can be read by the industrial robot 21, thereby driving the industrial robot 21 to perform the polishing operation.

[0043] The elliptical vibration polishing assembly 1 is mounted on the end flange of the robot, and comprises a pressure regulating cylinder 14, a motor 13, an electric slip ring 12 and an ultrasonic vibration polishing unit 11 connected in series. The main shaft of the motor 13 passes through the electric slip ring 12 and is key-connected to the ultrasonic vibration polishing unit 11; the ultrasonic vibration polishing unit 11 comprises a housing 115 and an ultrasonic elliptical vibrator 112 coaxially fixed in the housing 115; an ultrasonic horn 1124 is coaxially arranged at the end of the ultrasonic elliptical vibrator 112, and a piezoelectric detection element 1125 is arranged on the ultrasonic horn 1124, and The end thereof is sequentially sleeved with a sleeve 1126 and a clamp 1127, the clamp 1127 passes through the outer shell 115 and extends to its outside, and the end of the clamp clamps and fixes a polishing head 1128, and the shape of the polishing head 1128 can be selected according to actual needs, such as a spherical head shape, a cylindrical shape, or a cylindrical shape with a spherical head shape; the pressure regulating cylinder 14 pushes the ultrasonic vibration polishing unit 11 to achieve soft contact with the workpiece, and at the same time, the main shaft of the motor 13 drives the polishing head 1128 to rotate, and the ultrasonic elliptical vibrator 112 drives the polishing head 1128 to vibrate elliptically via the ultrasonic amplitude rod 1124.

[0044] An aspheric optical element 5 to be polished is installed on the polishing workbench, and a corresponding polishing tool control system is provided on the polishing workbench. The elliptical vibration polishing assembly 1 and the polishing tool control system are connected by an electrical circuit, which can realize the regulation of parameters such as the polishing head speed, pressure, amplitude and frequency.

[0045] The polishing liquid supply module 3 includes a liquid storage barrel 31 placed on the edge of the workbench, an infusion tube leading from the liquid storage barrel 31, a peristaltic pump 32 and an onboard polishing liquid control system. The polishing liquid control system is used to control the output of the polishing liquid pumped out by the peristaltic pump 32 to achieve quantitative addition of polishing liquid during the robot polishing process.

[0046] The elliptical vibration polishing assembly 1 comprises a pressure-regulating cylinder 14, a motor 13, an electric slip ring 12, and an ultrasonic vibration polishing unit 11, connected in series. These components form the polishing tool control assembly. The main shaft of the motor 13 passes through the electric slip ring 12 and is keyed to the ultrasonic vibration polishing unit 11. The lower cable of the electric slip ring 12 is connected to the ultrasonic vibration polishing unit 11, while the upper cable is connected to the ultrasonic vibration controller and power amplifier, primarily providing external power to the ultrasonic vibration polishing unit 11.

[0047] like Figure 2 and Figure 3 As shown, there are respectively a structural diagram and a cross-sectional view of the elliptical vibration polishing assembly 1 provided in this embodiment. The pressure regulating cylinder 14 is fixed on a mounting flange 15 connected to the end of the industrial robot 21, and the cylinder push plate of the pressure regulating cylinder 14 is connected to the flange mounting plate of the motor 13 through another connecting plate.

[0048] The motor 13 is selected as a spindle servo motor, which drives its spindle 16 to rotate through a coupling. The end of the spindle 16 transmits the rotational motion to the ultrasonic vibration polishing unit 11 through a key connection, so that the ultrasonic vibration polishing unit 11 rotates in close contact with the polishing workpiece while superimposing elliptical ultrasonic vibrations;

[0049] The pressure regulating cylinder 14 is a double-acting cylinder equipped with a proportional pressure valve (not shown). This valve adjusts the cylinder thrust, thereby controlling the soft contact pressure between the polishing head 1128 and the workpiece. During operation, the cylinder thrust is first adjusted to balance the cylinder thrust with the weight of the polishing tool. The pressure valve is then adjusted to control the contact pressure between the polishing head and the workpiece.

[0050] The ultrasonic vibration polishing unit 11 includes a housing 115 and an ultrasonic elliptical vibrator 112 coaxially fixed in the housing 115; an ultrasonic horn 1124 is coaxially arranged at the end of the ultrasonic elliptical vibrator 112. The ultrasonic horn 1124 is made of aluminum alloy or titanium alloy and can amplify the amplitude.

[0051] like Figure 4 As shown, the ultrasonic vibration polishing unit 11 also includes an ultrasonic vibration controller 111, a dual-channel ultrasonic power supply 113 (driving circuit), and a power amplifier group 114. The ultrasonic vibration controller 111 includes a main control CPU, a main power supply, a power control circuit, and a current sampling and detection circuit. When the ultrasonic vibration polishing unit 11 is started, the power control circuit within the ultrasonic vibration controller 111 begins frequency sweeping. The current sampling and detection circuit receives the current signal transmitted back from the piezoelectric detection element 1125 of the ultrasonic vibration polishing unit 11. By analyzing the current changes and phase differences between the two groups of piezoelectric detection elements, it determines the resonant operating point of the ultrasonic vibration polishing unit 11 and controls the ultrasonic power supply to output an electrical signal of the corresponding frequency. During polishing, the main control CPU continues to analyze the returned current signal and performs impedance matching through the function control circuit. The output voltage of the power supply is adjusted according to changes in the load to ensure a stable operating frequency, thereby causing the ultrasonic vibration polishing unit 11 to produce a stable elliptical vibration trajectory, thereby ensuring polishing quality.

[0052] The aforementioned dual-channel ultrasonic power supply 113 is used to generate two high-frequency AC signals with independently adjustable amplitude and frequency. Through its internal synchronous timing circuit, it realizes accurate control of the phase of the two signals and transmits the AC signals to the two-way power amplifier group 114 to realize precise control of the elliptical vibration trajectory of the polishing head.

[0053] The aforementioned power amplifier is divided into a bending vibration power amplifier and a longitudinal vibration power amplifier. The two are independently controlled to amplify the high-frequency sinusoidal electrical signal transmitted by the ultrasonic power supply and transmit it to the longitudinal vibration and bending vibration piezoelectric ceramic groups respectively, driving the end polishing head to generate elliptical trajectory vibration.

[0054] like Figure 5 As shown, the end of the ultrasonic transformer 1124 is sequentially connected with a sleeve 1126 and a clamp 1127, the clamp 1127 extends through the shell 115 to its outside, and the end of the clamp clamps and fixes a polishing head 1128; the pressure regulating cylinder 14 pushes the ultrasonic vibration polishing unit 11 to achieve soft contact with the workpiece, and at the same time, the main shaft of the motor 13 drives the polishing head 1128 to rotate, and the ultrasonic elliptical vibrator 112 drives the polishing head 1128 to vibrate elliptically via the ultrasonic transformer 1124.

[0055] Housing 115 is a hollow cylinder. Ultrasonic elliptical transducer 112 also includes a piezoelectric ceramic assembly and an end cap 1121. End cap 1121, piezoelectric ceramic assembly, and ultrasonic horn 1124 are sequentially connected. Both end cap 1121 and ultrasonic horn 1124 are provided with radially symmetrical stationary mounting holes 1130 for securing the ultrasonic transducer without affecting the operating mode shape of the overall polishing device.

[0056] like Figure 6 As shown, the housing 115 is provided with a stationary support threaded hole 1129 that matches the stationary mounting hole 1130. The stationary mounting hole 1130 and the stationary support threaded hole 1129 are connected by a screw, as shown in FIG. Figure 8 As shown, the vibration mode and node diagram of the ultrasonic elliptical vibrator 112 in the elliptical vibration polishing assembly 1. Through modal simulation, the elliptical vibrator (i.e., the ultrasonic vibration polishing unit 11) can achieve modal merging under second-order longitudinal vibration and fourth-order bending vibration, and has two overlapping standing wave nodes. Fixing the vibrator at these two standing wave nodes can effectively prevent the loosening of the fixing screws while ensuring the generation of high-frequency resonance, and improve the stability of the ultrasonic elliptical vibrator 112.

[0057] The piezoelectric ceramic group includes a longitudinal vibration piezoelectric ceramic group 1122 and a bending vibration piezoelectric ceramic group 1123. The longitudinal vibration piezoelectric ceramic group 1122 includes two annular piezoelectric ceramics, and the bending vibration piezoelectric ceramic group 1123 includes eight semicircular annular piezoelectric ceramics, with each pair of two piezoelectric ceramics forming four annular piezoelectric ceramics. Adjacent piezoelectric ceramics are separated by electrodes, and the connection between the bending vibration piezoelectric ceramic group 1123 and the longitudinal vibration piezoelectric ceramic group 1122 shares an electrode (not shown). The electrode is used to transmit the electrical signals from the bending vibration power amplifier and the longitudinal vibration power amplifier to the bending vibration and longitudinal vibration piezoelectric ceramic group. The piezoelectric ceramic group converts the excitation electrical signals received by the electrode into a composite vibration in both the longitudinal and bending directions, thereby achieving high-frequency elliptical vibration of the polishing head. The second-order longitudinal vibration and the fourth-order bending vibration resonant frequencies are consistent, with two overlapping standing wave nodal surfaces.

[0058] The piezoelectric ceramic assembly and ultrasonic horn 1124 are both hollow, open-hole structures. The end cap 1121 is provided with a countersunk hole, and the ultrasonic horn 1124 is threaded. Bolts are used to nest and secure the end cap 1121, piezoelectric ceramic assembly, and ultrasonic horn 1124. Both the end cap 1121 and ultrasonic horn 1124 have radially symmetrical stationary mounting holes for securing the ultrasonic elliptical vibrator 112.

[0059] like Figure 7 As shown, the vibration trajectory of the tool tip is measured by a Doppler laser vibrometer at the clamping position of the elliptical vibration polishing component 1, which can be fitted into an ellipse with a major axis of 4.9um and a minor axis of 1.9um. The phase difference between the two amplitudes is relatively consistent with the power supply excitation signal, and the vibration frequency reaches 49.735kHz, which proves the feasibility of the optical aspheric robot elliptical vibration polishing device provided in this application.

[0060] In traditional cutting processes, the diamond tool is subjected to large impacts during the processing, which will cause the vibration node position to shift, resulting in a change in the resonant frequency. During this impact process, the diamond tool wears and the piezoelectric ceramic heats up, shortening the life of the device. At the same time, due to the increase in temperature, the processing trajectory deviates from the designed trajectory, and the impedance increases, the loss increases, and the electromechanical conversion efficiency is reduced, further reducing the processing quality and accuracy. Since the polishing head and the workpiece of this application are in soft contact, the impact of the node offset is very small, so the elliptical amplitude of the entire polishing device is more stable, which is more conducive to improving the processing accuracy, and the processing quality and stability are also greatly improved.

[0061] In another embodiment, a method for polishing an optical aspheric surface using the aforementioned robotic elliptical vibration polishing device is disclosed, the method comprising the following steps:

[0062] First, the fixed-point polishing method is used to obtain the removal function of the polishing head 1128 under specific materials and polishing environments, that is, the amount of material removed per unit time; an interferometer is used to obtain the surface error data of the workpiece to be polished, and the removal function and surface error data of the workpiece to be polished are used to obtain the running trajectory of the polishing head 1128, and according to the surface error equation, removal function and curvature of the workpiece, the working parameters such as the motion position and speed of the industrial robot 21 and the corresponding polishing liquid flow rate are planned.

[0063] Using a four-point method, the workpiece to be polished is calibrated in a fixed position on the workbench, achieving submillimeter positioning accuracy. The industrial robot's own repeatability reaches ±0.05mm, ensuring the precise positional relationship between the polishing head and the workpiece. As the industrial robot 21 controls the elliptical vibrating polishing assembly 1 along the polishing path across the workpiece's optical surface, the normal of the polishing head 1128 coincides with the normal of the workpiece's optical surface. As the vibrating polishing head moves to different polishing zones, the fluid supply system controls the peristaltic pump's fluid flow rate according to program settings, adapting to various processes, such as rough polishing and fine polishing.

[0064] During polishing, the cylinder thrust of the pressure regulating cylinder 14 is first adjusted to balance the force of gravity on the ultrasonic vibration polishing unit 11. The cylinder thrust of the pressure regulating cylinder 14 is further adjusted to control the soft contact pressure between the polishing head and the workpiece. The motor 13 is controlled to rotate synchronously with the ultrasonic vibration polishing unit 11. Simultaneously, the ultrasonic elliptical vibrator 112 is controlled to output a second-order longitudinal vibration signal and a fourth-order bending vibration signal with consistent resonant frequencies, driving the polishing head 1128 to elliptically vibrate and polish the workpiece.

[0065] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0066] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0067] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected to each other and the relative position relationship after the connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after the connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after the connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0068] In addition, in the embodiments of the present application, the mathematical concepts mentioned include symmetry, equality, parallelism, and perpendicularity. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense. A small amount of deviation is allowed, and it is possible to be approximately symmetric, approximately equal, approximately parallel, or approximately perpendicular. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0069] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An optical aspheric robot elliptical vibration polishing device, characterized in that: The invention comprises an elliptical vibration polishing assembly (1), wherein the elliptical vibration polishing assembly (1) comprises a pressure regulating cylinder (14), a motor (13), an electric slip ring (12) and an ultrasonic vibration polishing unit (11) connected in series in sequence, wherein the main shaft of the motor (13) passes through the electric slip ring (12) and is key-connected with the ultrasonic vibration polishing unit (11); the ultrasonic vibration polishing unit (11) comprises a housing (115) and an ultrasonic elliptical vibrator (112) coaxially fixed in the housing (115); the ultrasonic elliptical vibrator (112) comprises an ultrasonic amplitude rod (1124) coaxially arranged in sequence ), a sleeve (1126) and a clamp (1127); the clamp (1127) extends through the housing (115) to the outside thereof, and a polishing head (1128) is clamped and fixed at its end; the pressure regulating cylinder (14) is used to push the ultrasonic vibration polishing unit (11) so that the polishing head (1128) and the workpiece achieve soft contact; the main shaft of the motor (13) is used to drive the polishing head (1128) to rotate; the ultrasonic elliptical vibrator (112) is used to drive the polishing head (1128) to perform elliptical vibration via the ultrasonic amplitude transformer (1124).

2. The optical aspheric robot elliptical vibration polishing device according to claim 1, characterized in that: The ultrasonic horn (1124) is made of aluminum alloy or titanium alloy.

3. The optical aspheric robot elliptical vibration polishing device according to claim 1, characterized in that: The pressure regulating cylinder (14) is a double-acting cylinder on which a proportional pressure valve is provided, and the proportional pressure valve is used to regulate the cylinder thrust.

4. The optical aspheric robot elliptical vibration polishing device according to claim 1, characterized in that: The cylinder push plate of the pressure regulating cylinder (14) is connected to the flange mounting plate on the motor (13) through a connecting plate.

5. The optical aspheric robot elliptical vibration polishing device according to claim 1, characterized in that: The housing (115) is a hollow cylinder. The ultrasonic elliptical vibrator (112) further comprises a piezoelectric ceramic group and an end cover (1121). The end cover (1121), the piezoelectric ceramic group and the ultrasonic amplitude transformer (1124) are connected in sequence. The end cover (1121) and the ultrasonic amplitude transformer (1124) are respectively provided with radially symmetrical stationary point mounting holes (1130). The housing (115) is provided with a stationary point support threaded hole (1129) matching the stationary point mounting hole (1130). The stationary point mounting hole (1130) and the stationary point support threaded hole (1129) are connected by a screw.

6. The optical aspheric robot elliptical vibration polishing device according to claim 5, characterized in that: The ultrasonic vibration polishing unit (11) further includes an ultrasonic vibration controller (111), an ultrasonic power supply (113) and a power amplifier group (114). The ultrasonic vibration controller (111) is used to determine the resonant operating point of the ultrasonic vibration polishing unit (11) and control the ultrasonic power supply (113) to output an electrical signal of a corresponding frequency to the power amplifier group (114); the power amplifier group (114) is used to amplify the gain of the electrical signal and transmit it to the piezoelectric ceramic group, thereby driving the polishing head (1128) to vibrate in an elliptical trajectory.

7. The optical aspheric robot elliptical vibration polishing device according to claim 1, characterized in that: The polishing device further comprises an industrial robot (21) and a polishing liquid supply module (3), wherein the elliptical vibration polishing assembly (1) is mounted on the processing end of the industrial robot (21), and the liquid outlet end of the polishing liquid supply module (3) is located above the polishing position and is used for supplying polishing liquid during polishing.

8. A method for polishing an optical aspheric surface using an elliptical vibration polishing device of an optical robot according to any one of claims 1 to 7, characterized in that: Traversing the workpiece surface according to the preset running track of the polishing head (1128) to polish, including: S1 adjusts the cylinder thrust of the pressure regulating cylinder (14) so ​​that the cylinder thrust is balanced with the gravity of the ultrasonic vibration polishing unit (11); S2 continues to adjust the cylinder thrust of the pressure regulating cylinder (14) to control the soft contact pressure between the polishing head (1128) and the workpiece; S3 controls the motor (13) to rotate, thereby driving the ultrasonic vibration polishing unit (11) to rotate synchronously, and simultaneously controls the ultrasonic elliptical vibrator (112) to output a second-order longitudinal vibration signal and a fourth-order bending vibration signal with consistent resonant frequencies, thereby driving the polishing head (1128) to perform elliptical vibration to achieve polishing of the workpiece.

9. The method according to claim 8, wherein Before step S1, a fixed-point polishing method is used to obtain a removal function of the polishing head (1128) under a specific material and polishing environment; an interferometer is used to obtain surface error data of the workpiece to be polished, and the removal function and surface error data of the workpiece to be polished are used to obtain the preset running trajectory of the polishing head (1128); and according to the surface error data and curvature of the workpiece, the working parameters of the industrial robot (21) and the corresponding polishing liquid flow rate are planned.

10. The method according to claim 8, wherein When the industrial robot (21) controls the elliptical vibration polishing assembly (1) to traverse the optical curved surface of the workpiece along the polishing trajectory, the normal line of the polishing head (1128) coincides with the normal line of the optical curved surface of the workpiece.

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