A shear thickening polishing device and method for optical lenses

Abstract

The application discloses a kind of shear thickening polishing device and method of optical lens, the device includes rotating motor, liquid supply pump, polishing liquid tank, rotating platform, fine adjustment platform, lens clamp, structured polishing tool, angle-changing rotary table and three-axis linkage platform;The three-axis linkage platform is used to realize the adjustment of structured polishing tool in X, Y and Z three direction positions.The structured polishing tool of the application can effectively drive shear thickening polishing fluid to flow, and realize low-damage or even non-damage polishing of optical lens, and can realize nanometer or even sub-nanometer roughness.Based on the shear thickening polishing characteristics, the surface material is removed using full-aperture cambered surface polishing head to improve efficiency first, and then sub-aperture spherical polishing head is used to improve surface quality, which can ensure material removal uniformity by adjusting polishing gap, and ensure surface shape precision.

Description

Technical Field

[0001] This invention belongs to the field of precision / ultra-precision machining, and specifically relates to a shearing, thickening, and polishing device and method for optical lenses. Background Technology

[0002] Optical lenses are the most important components of optical lenses, which are mainly used in traditional fields such as digital cameras, projection equipment, astronomy, aerospace, and industry. Optical lenses are also the core component of the lithography machine industry's supply chain. Optical lenses include plano-convex lenses, biconvex lenses, plano-concave lenses, and biconcave lenses of various wavelengths made from materials such as fused silica, calcium fluoride, magnesium fluoride, silicon, germanium, and zinc selenide.

[0003] For small, highly integrated microarray lenses, the surface shape, size, and surface quality determine their final application performance, typically requiring nanometer-level surface quality and micrometer-level surface shape accuracy. For components with special performance requirements, even nanometer-level roughness and submicrometer-level surface shape accuracy are required, free from surface scratches, pitting, and edge defects. Currently, optical lenses commonly use spherical center polishing, CNC tool polishing, and magnetorheological polishing techniques. However, these processes have shortcomings. For example, spherical center polishing and CNC tool polishing are contact polishing methods, which are prone to surface defects and damage. Magnetorheological polishing has low processing efficiency and high cost, and its core technology has long been monopolized by foreign countries. Shear thickening polishing, a non-contact polishing method, is suitable for complex curved surfaces and has high processing efficiency, making it a valuable supplement to existing lens processing techniques.

[0004] Chinese patent application CN201280058226.6 discloses a polishing device for optical lenses. This device is based on the principle of quasi-spherical center polishing and uses a specific positioning device and an axis rotation device to allow the lens to move on the corresponding spherical surface, thereby achieving uniform polishing of the lens surface. However, the polishing method is a contact polishing method, and defects such as scratches and pitting are prone to appear on the polished surface.

[0005] Chinese patent application CN202011043550.3 discloses a shaping device and method based on shear thickening polishing. In use, this device requires the preparation of multiple polishing liquids, has low polishing efficiency, is complicated to operate, and has a complicated process for solving the polishing time.

[0006] Chinese patent application 202010492399.5 discloses a polishing head and polishing method suitable for shear thickening polishing. This invention can achieve localized processing of shear thickening at specific points and with controllable pressure. However, the device is difficult to assemble, has poor surface shape control, and is difficult to achieve in batch processing.

[0007] Chinese patent application CN202011504672.8 discloses a CCOS shearing thickening polishing method. This method has the ability to modify the surface of workpieces with low, medium, and high precision. However, this method is not suitable for processing curved lens surfaces, and it is difficult to achieve trajectory movement of the polishing tool.

[0008] In summary, current optical lens polishing methods, when using contact polishing methods to polish simple curved surfaces such as spheres and cylinders, are prone to surface scratches and pitting, and the lens surface shape is difficult to control. Non-contact polishing methods for optical lenses suffer from low processing efficiency and are not suitable for mass production. Summary of the Invention

[0009] To address the aforementioned problems in the existing technology, this invention proposes a high-efficiency, high-precision, and non-destructive shearing, thickening, and polishing device and method for optical lenses.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] A shearing, thickening, and polishing device for optical lenses includes a rotary motor, a liquid supply pump, a polishing liquid tank, a rotary platform, a fine-tuning platform, a lens fixture, a structured polishing tool, a variable-angle turntable, and a three-axis linkage platform.

[0012] The structured polishing tool is fixed to a rotary motor via a coupling;

[0013] The rotary motor is mounted on a variable-angle turntable;

[0014] The variable angle turntable is connected to the three-axis linkage platform, which is used to adjust the position of the structured polishing tool in the X, Y and Z directions.

[0015] The polishing liquid tank is fixedly installed on the rotating platform via a fine-tuning platform;

[0016] A lens fixture is installed at the bottom of the polishing liquid tank, and a lens is installed on the lens fixture.

[0017] Furthermore, the structured polishing tool is a sub-diameter spherical polishing head or a full-diameter arc-shaped polishing head.

[0018] Furthermore, the rotation axis of the full-diameter arc polishing head is configured to be either vertical or horizontal.

[0019] Furthermore, the lens and the structured polishing tool are completely immersed in the polishing fluid.

[0020] Furthermore, the structured polishing tool has grooves on its surface, including elongated grooves, concentric annular grooves, and circular spot grooves; a damping polishing pad with a thickness of 0.7-0.8 mm is pasted inside the grooves.

[0021] A shear-thickening polishing method for optical lenses, utilizing a shear-thickening polishing device for optical lenses, includes the following steps:

[0022] Step 1: Fix the lens to the lens fixture using filler glue, then connect the lens fixture to the polishing liquid tank with bolts. After that, use the fine adjustment platform to center and level the lens so that the runout error is within ±10 µm.

[0023] Step 2: Install the full-diameter arc polishing head, and use a variable angle turntable to adjust the tilt angle of the rotary motor to 15°-45°. Adjust the gap between the lens and the full-diameter arc polishing head to 0.1-0.3 mm, turn on the liquid supply pump and set the flow rate of the shear-thickening polishing liquid to 50-150 ml / min, and adjust the rotation speed of the rotary motor to 1200-3000 rpm; pre-polish the lens surface.

[0024] Step 3: Measure the lens surface shape error, calculate the dwell time and feed speed corresponding to the amount of material removed, and set the spiral or grating motion trajectory.

[0025] Step 4: Install the sub-aperture spherical polishing head, and use the variable angle turntable to adjust the tilt angle of the rotary motor to 15°-45°. Adjust the gap between the lens and the sub-aperture curved polishing head to 0.1-0.3 mm, turn on the three-axis linkage platform, turn on the liquid supply pump and set the shear-thickening polishing liquid flow rate to 50-150 ml / min, adjust the rotary motor speed to 1200-3000 rpm, and perform fine polishing on the lens surface according to the scanning trajectory.

[0026] Furthermore, the shear-thickening polishing fluid includes deionized water, polyhydroxy polymer particles, and abrasive particles. The mass proportion of the polyhydroxy polymer particles is 25% to 35%. The abrasive particles are selected from one or more combinations of alumina, silicon carbide, diamond, cerium oxide, and zirconium oxide, with a particle size of 0.5 to 10 μm and a mass proportion of 15% to 25%. The remainder is deionized water.

[0027] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0028] 1. The structured polishing tool of the present invention can effectively drive the flow of shear-thickened polishing fluid and achieve low-damage or even non-damage polishing of optical lenses, achieving nano- or even sub-nanometer roughness.

[0029] 2. Based on the shear-thickening polishing characteristics, this invention first uses a full-diameter arc-shaped polishing head to remove surface material to improve efficiency, and then uses a sub-diameter spherical polishing head to improve surface quality. The uniformity of material removal can be ensured by adjusting the polishing gap, thus guaranteeing the surface shape accuracy. Attached Figure Description

[0030] Figure 1 Schematic diagram of an optical lens shearing, thickening, and polishing device;

[0031] Figure 2 This is a schematic diagram of the sub-aperture polishing process;

[0032] Figure 3 for Figure 2 Enlarged view of point A.

[0033] Figure 4 This is a schematic diagram of full-diameter concave surface polishing.

[0034] Figure 5 This is a schematic diagram of full-diameter convex surface polishing.

[0035] Figure 6 Schematic diagram of a spherical polishing head with annular groove;

[0036] Figure 7 A schematic diagram of a spherical polishing head with a fan-shaped groove;

[0037] Figure 8 A schematic diagram of a dot-shaped spherical polishing head;

[0038] Figure 9 Schematic diagram of a full-diameter concave polishing head;

[0039] Figure 10 This is a schematic diagram of a full-diameter convex polishing head.

[0040] In the diagram: 1-Rotary motor; 2-Liquid supply pump; 3-Lens; 4-Polishing liquid tank; 5-Rotary platform; 6-Fine adjustment platform; 7-Lens fixture; 8-Structured polishing tool; 9-Variable angle turntable; 10-Three-axis linkage platform. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] like Figure 1-10As shown, the working principle and specific process of this invention are as follows: During polishing, the rotating platform 5 drives the lens 3 to rotate. First, a full-aperture arc polishing head is used to quickly remove the surface material of the lens 3 and reduce the roughness to 1-2 nm. The full-aperture arc polishing head needs to be selected according to the lens 3's aperture of 100-200 mm and radius of curvature to match the surface shape. Then, a spherical polishing head is used to scan the spiral polishing trajectory set for different lens 3 apertures of 100-200 mm and radius of curvature to further optimize the surface quality and surface shape accuracy. The surface polishing pad of the structured polishing tool 8 will drive the shear-thickening polishing liquid to form a certain shear rate, so that the surface of the lens 3 and the shear-thickening polishing liquid form relative motion. The polishing liquid flow rate is set to 50-150 ml / min to uniformly deliver the polishing liquid to the surface of the lens 3, and to ensure that the generated shear rate can cause the polishing liquid to have a shear-thickening effect. The motor speed is adjusted to 1200-3000 rpm. This achieves high-efficiency, high-precision, and non-destructive polishing of the optical lens 3. Furthermore, the shear-thickening polishing fluid possesses fluidity, enabling the formed "flexible abrasive" to maintain good contact with various workpiece surfaces. This effectively removes microscopic peaks from the lens 3 surface, improving polishing efficiency. Ultimately, under the shear force and dynamic pressure generated by the shear-thickening effect, efficient material removal is achieved in a flexible contact state.

[0043] An embodiment of the present invention: polishing of a 100mm diameter positive meniscus lens.

[0044] like Figure 1-10 As shown, this embodiment is used to polish a 100mm diameter positive meniscus lens. The present invention is attached to a three-axis linkage platform 10 and is composed of a rotary motor 1, a liquid supply pump 2, a polishing liquid tank 4, a rotary platform 5, a fine adjustment platform 6, a lens fixture 7, a structured polishing tool 8 and a variable angle turntable 9.

[0045] The structured polishing tool 8 is fixed to the rotary motor 1 via a coupling. Driven by the rotary motor 1, it rotates and can control the change of the shear rate of the polishing fluid by changing the rotation speed, thereby achieving different shear thickening polishing effects.

[0046] The rotary motor 1 is mounted on the variable-angle turntable 9, which can adjust the contact point between the structured polishing tool 8 and the workpiece during the polishing process. This allows the rotary motor 1 and the structured polishing tool 8 to tilt at any angle, enabling them to contact any position on the surface of the lens 3.

[0047] The variable angle turntable 9 is connected to the three-axis linkage platform 10. Driven by the three-axis linkage platform 10, the structured polishing tool 8 can be adjusted in the X, Y and Z directions, thereby maintaining a constant gap between the structured polishing tool 8 and the lens 3.

[0048] The polishing liquid tank 4 is bolted onto the rotating platform 5 and rotates continuously under the drive of the rotating platform 5, with the rotation speed adjustable. The lens 3 is fixed to the lens fixture 7 with filler adhesive, and then the lens fixture 7 is fixed to the polishing liquid tank 4. The lens 3 and the polishing liquid tank 4 rotate with the rotating platform 5, thereby achieving continuous and uniform polishing of the workpiece.

[0049] Furthermore, the structured polishing tool 8 can be divided into a sub-aperture spherical polishing head and a full-aperture arc-shaped polishing head. The sub-aperture polishing head scans and polishes the lens surface via a trajectory movement. The full-aperture arc-shaped polishing head can polish the entire lens surface simultaneously, and the gap can be controlled during the polishing process to ensure uniform material removal and maintain the surface shape. All of the structured polishing tools 8 have grooves on their surfaces for attaching polishing pads, which drive the shear-thickening polishing fluid. Through the relative movement between the polishing fluid and the workpiece surface, effective removal of curved surface materials is achieved.

[0050] Furthermore, to accommodate the machining of convex and concave surfaces of lens 3 with different radii of curvature, the full-diameter arc polishing head can be configured for both vertical and horizontal placement. The uniformity of material removal is ensured by adjusting the size of the polishing head and the gap between the polishing head and the workpiece. To achieve better polishing results, lens 3 and the polishing head can be completely immersed in the polishing fluid. This ensures sufficient fluid supply to the contact area, allowing the polishing fluid to better exhibit solid properties, enhancing the holding force on the abrasive grains, and increasing the dynamic pressure effect. This, in turn, increases the contact pressure of the abrasive grains on the workpiece, achieving efficient and high-precision polishing of the optical lens.

[0051] A shear-thickening polishing method for optical lenses, utilizing a shear-thickening polishing device for optical lenses, includes the following steps:

[0052] Step 1: Fix the lens onto the lens holder 7 using filler glue, then connect the lens holder 7 to the polishing liquid tank 4 with bolts. After that, use the fine-tuning platform 6 to center and level the lens 3. The runout error should be less than ±10 µm.

[0053] Step 2: Install the full-diameter arc polishing head and use the variable angle turntable 9 to adjust the tilt angle of the rotary motor 1 (15°-45°). Adjust the gap between the lens 3 and the full-diameter arc polishing head to 0.1-0.3 mm, turn on the liquid supply pump 2 and set the flow rate of the shear-thickening polishing liquid to 50-150 ml / min. Adjust the speed of the rotary motor 1 (1200-3000 rpm) to complete the pre-polishing of the lens 3 surface.

[0054] Step 3: Measure the surface shape error, calculate the dwell time and feed speed corresponding to the amount of material removed, and set the spiral or grating motion trajectory.

[0055] Step 4: Install the sub-diameter spherical polishing head, and use the variable angle turntable 9 to adjust the tilt angle of the rotary motor 1 (15°-45°). Adjust the gap between the lens 3 and the full-diameter arc polishing head to 0.1-0.3 mm, turn on the three-axis linkage platform 10, turn on the liquid supply pump 2 and set the shear thickening polishing liquid flow rate to 50-150 ml / min, adjust the rotation speed of the rotary motor 1 (1200-3000 rpm), and polish the lens surface according to the scanning trajectory.

[0056] Furthermore, the polishing fluid used for shear thickening includes deionized water, polyhydroxy polymer particles, and abrasive particles. The polyhydroxy polymer particles have a mass ratio of 25% to 35%. The abrasive particles are selected from one or more combinations of alumina, silicon carbide, diamond, cerium oxide, and zirconium oxide, with a particle size of 0.5 to 10 μm and a mass ratio of 15% to 25%. The remainder is deionized water.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A shear-thickening polishing method for an optical lens, wherein a shear-thickening polishing device for an optical lens is used for polishing, the shear-thickening polishing device for an optical lens includes a rotary motor (1), a liquid supply pump (2), a polishing liquid tank (4), a rotary platform (5), a fine-tuning platform (6), a lens fixture (7), a structured polishing tool (8), a variable angle turntable (9), and a three-axis linkage platform (10). The structured polishing tool (8) is fixed to the rotary motor (1) by a coupling; The rotary motor (1) is mounted on the variable angle turntable (9); The variable angle turntable (9) is connected to the three-axis linkage platform (10), which is used to adjust the position of the structured polishing tool (8) in the X, Y and Z directions. The polishing liquid tank (4) is fixedly installed on the rotating platform (5) via the fine-tuning platform (6); A lens clamp (7) is installed at the bottom of the polishing liquid tank (4), and a lens (3) is installed on the lens clamp (7). Its features are: The polishing method includes the following steps: Step 1: Use filler glue to fix the lens (3) onto the lens fixture (7), then connect the lens fixture (7) to the polishing liquid tank (4) with bolts, and then use the fine adjustment platform (6) to center and level the lens (3) so that the runout error is within ±10 µm. Step 2: Install the full-diameter arc polishing head, use the variable angle turntable (9) to adjust the tilt angle of the rotary motor (1) to 15°-45°, adjust the gap between the lens (3) and the full-diameter arc polishing head to 0.1-0.3 mm, turn on the liquid supply pump (2) and set the flow rate of the shear thickening polishing liquid to 50-150 ml / min, adjust the speed of the rotary motor (1) to 1200-3000 rpm; pre-polish the surface of the lens (3); Step 3: Measure the surface shape error of lens (3), calculate the dwell time and feed speed corresponding to the amount of material removed, and set the spiral or grating motion trajectory; Step 4: Install the sub-diameter spherical polishing head, use the variable angle turntable (9) to adjust the tilt angle of the rotary motor (1) to 15°-45°, adjust the gap between the lens (3) and the sub-diameter arc polishing head to 0.1-0.3 mm, turn on the three-axis linkage platform (10), turn on the liquid supply pump (2) and set the flow rate of the shear thickening polishing liquid to 50-150 ml / min, adjust the speed of the rotary motor (1) to 1200-3000 rpm, and perform fine polishing on the surface of the lens (3) according to the scanning trajectory.

2. The shearing thickening polishing method for an optical lens according to claim 1, characterized in that: The structured polishing tool (8) is a sub-diameter spherical polishing head or a full-diameter arc surface polishing head.

3. The shearing thickening polishing method for an optical lens according to claim 2, characterized in that: The rotation axis of the full-diameter arc polishing head is set to either vertical or horizontal.

4. The shearing thickening polishing method for an optical lens according to claim 1, characterized in that: The lens (3) and the structured polishing tool (8) are completely immersed in the polishing liquid.

5. The shearing thickening polishing method for an optical lens according to claim 1, characterized in that: The structured polishing tool (8) has grooves on its surface, including elongated grooves, concentric annular grooves and circular spot grooves; a damping polishing pad with a thickness of 0.7-0.8 mm is pasted in the groove.

6. The shearing thickening polishing method for an optical lens according to claim 1, characterized in that: The shear-thickening polishing fluid comprises deionized water, polyhydroxy polymer particles, and abrasive grains. The polyhydroxy polymer particles account for 25% to 35% by mass. The abrasive grains are selected from one or more combinations of alumina, silicon carbide, diamond, cerium oxide, and zirconium oxide, with a particle size of 0.5 to 10 μm and a mass ratio of 15% to 25%. The remainder is deionized water.

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