Multi-field composite non-contact polishing device and method

Abstract

The present invention discloses a multi-field composite non-contact polishing device and method, which can achieve high-efficiency and high-quality polishing of workpieces through the composite of temperature field, electric field, magnetic field, chemical field, and mechanical field. The temperature control system can achieve constant control of the temperature of the non-contact polishing liquid, ensuring that the polishing liquid always maintains a good shear thickening effect in a constant temperature field during the polishing process. The abrasive particles polarized in the dielectric medium by the alternating power supply are moved by the dielectrophoretic force, preventing the sedimentation of most of the abrasive particles during the polishing process and improving the polishing removal rate. A magnetic field is applied between the polishing tool and the workpiece to promote the adsorption of magnetic abrasive particles in the polishing liquid on the processed surface of the workpiece, allowing the abrasive particles to enter more corners of the complex surface of the workpiece, and increasing the pressure of the abrasive particles on the workpiece surface during polishing, thereby improving the polishing efficiency. The oxidant in the polishing liquid removes the surface oxide layer through the mechanical action of the abrasive particles, and this cycle can eventually achieve a high-quality surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-precision machining, and in particular relates to a multi-field composite non-contact polishing device and method. Background Art

[0002] In recent years, with the advancement of optoelectronics technology toward miniaturization and integration, high-precision microstructured optical components with tiny topological geometries have gained widespread application due to their technological advantages of high integration, lightweight design, high imaging quality, and high resolution. Fresnel structures, microlens arrays, and microprism structures, for example, play roles in imaging, focusing, and illumination in many optical systems. For microstructured components, surface accuracy determines their function, while surface quality determines their performance. Therefore, microstructured optical components with high surface quality requirements often require polishing after precision machining to eliminate surface / subsurface damage, improve the surface quality of the microstructure, and enhance the integrity of the microstructure joints.

[0003] The non-contact polishing method using non-Newtonian fluid as the polishing medium is a new ultra-precision machining process proposed in recent years. This method forms "particle clusters" through shear thickening, enhances the restraint force of the abrasive particles in the polishing liquid, and forms a "flexible fixed abrasive" at the processing position, thereby achieving the purpose of polishing by removing the surface material of the microstructure through the micro-cutting action of the abrasive particles. During the polishing process, there is no direct contact between the tool and the workpiece, and high-precision polishing can be performed without damaging the workpiece surface. Therefore, this polishing method is mostly used for polishing complex microstructure optical components. However, this method mainly involves immersing the workpiece in the polishing liquid for polishing. The abrasive particles in the polishing liquid are easy to settle, resulting in uneven concentration of the polishing liquid, fewer abrasive particles actually in contact with the workpiece, low polishing efficiency, and poor polishing quality.

[0004] Chinese patent CN 114473718 A discloses a non-contact polishing method and device for optical lenses. This invention is based on the principle of shear thickening and can achieve low-damage / damage-free polishing of curved lenses, ensuring good surface accuracy. However, it is impossible to perform conformal and high-quality processing on microstructures with more complex surface structures. Chinese patent CN102717325A discloses an ultra-precision surface polishing method based on the shear thickening effect of non-Newtonian fluids. This invention uses the shear thickening effect of non-Newtonian fluids to achieve high-quality and efficient polishing of various curved surfaces. However, this invention is only applicable to workpieces that are easy to clamp and rotate, and the abrasive particles are prone to sedimentation during the polishing process, resulting in reduced polishing efficiency. Chinese patent CN103331685A discloses a processing device based on a polishing method based on the shear thickening mechanism of non-Newtonian fluids. This invention can achieve polishing of planes, spheres, aspherical surfaces, and various complex curved surfaces, but for workpieces with complex microstructures on the surface, it is more difficult to maintain the surface accuracy of the microstructure. Chinese patent CN 216152043 U discloses an electric field and magnetic field coupled magnetorheological composite polishing disc and polishing machine. This invention uses the electrorheological and magnetorheological effects generated by the coupling of electric and magnetic fields to perform non-contact polishing on the workpiece. However, this invention uses a fixture to clamp the workpiece and place it in the polishing liquid for rotation, and relies solely on the "flexible grinding head" formed by the polishing liquid for polishing, resulting in low polishing efficiency and poor polishing quality. Chinese patent CN 111716232 B discloses a polishing method and device for microstructures. This invention is based on the shear thickening effect of non-Newtonian fluids, and uses a fixture to clamp the workpiece and vibrate it to achieve efficient polishing, which can achieve good surface roughness and surface shape accuracy. However, this device is only suitable for clamping and vibrating processing of small workpieces, and as polishing proceeds, the abrasive particles in the polishing liquid inevitably settle, making it impossible to adhere well to the workpiece surface for continuous efficient and high-quality processing.

[0005] Therefore, in view of the problems of poor conformal effect, low polishing efficiency and poor surface quality after polishing in the current polishing process of complex structure optical components, it is urgent to propose a new polishing method and device to improve the polishing efficiency, ensure the surface accuracy and improve the surface quality. Summary of the Invention

[0006] The present invention aims to overcome the deficiencies of the prior art and provide a multi-field composite non-contact polishing device and method that can improve polishing efficiency, ensure surface accuracy and simultaneously improve surface quality.

[0007] The technical solution adopted by the present invention to solve the above technical problems is:

[0008] A multi-field composite non-contact polishing device comprises a controller, a polishing liquid tank, a polishing liquid temperature control system, a polishing tool, an alternating power supply, a magnet, a turntable and a fixture.

[0009] The polishing fluid temperature control system includes a heater rod, a thermocouple, an external power supply, and a controller. The heater rod is placed above the polishing fluid, and the thermocouple is mounted on the inner wall of the polishing fluid tank to monitor the polishing fluid temperature in real time. Both the heater rod and the thermocouple are connected to the power supply and the controller. The heater rod manually activates the controller to heat the polishing fluid as needed. The thermocouple monitors the polishing fluid temperature in real time and transmits the analog-to-digital converted signal back to the controller. The controller then controls whether the heater rod continues heating, thereby achieving precise control of the constant temperature of the polishing fluid in the polishing fluid tank.

[0010] The fixture fixes the workpiece on the rotating worktable, and the polishing liquid is poured into the polishing liquid tank until it covers the gap between the polishing tool and the workpiece. The high-speed rotation of the polishing tool and the rotation of the workpiece causes thickening, thereby achieving shear removal of the workpiece surface material.

[0011] The positive and negative electrodes of the alternating power supply are connected to the polishing tool and the workpiece, respectively, so that an electric field is generated in the gap between the polishing tool and the workpiece. Due to the polarization effect, the abrasive particles in the polishing liquid are subjected to certain repulsive and attractive forces under the action of the electric field and move, so that most of the abrasive particles are distributed on the polishing surface of the polishing tool and the processed surface of the workpiece, thereby preventing the abrasive particles from settling.

[0012] The magnet is fixed on the rotating workbench and is located just below the fixture, providing a magnetic field between the polishing tool and the workpiece, so that the magnetic abrasive particles in the polishing liquid are tightly adsorbed on the processed surface of the workpiece.

[0013] Furthermore, the polishing liquid is a shear-thickening polishing liquid, comprising deionized water, polyhydroxy polymer particles, abrasive particles, an oxidizing agent, and a pH adjuster. The polyhydroxy polymer particles are present in a ratio of 35-45 wt%; the abrasive particles are silica with a particle size of 50 nm; magnetic abrasive particles are optionally added in a ratio of 15-25 wt%; the oxidizing agent is hydrogen peroxide at a ratio of 0.6%; the pH adjuster is citric acid adjusted to a pH of 9; and the remainder is deionized water.

[0014] Furthermore, the polishing tool includes a general polishing tool and a contour polishing tool wrapped with a damping polishing pad.

[0015] A multi-field composite non-contact polishing method, which uses a multi-field composite non-contact polishing device for polishing, comprises the following steps:

[0016] E. First, fix the workpiece on the rotating worktable with a fixture. Select different types of polishing tools according to the workpiece shape and surface features: For parallel microstructure workpieces with micro-feature depth less than 100 μm, the polishing tool used is a cylindrical tool. When the microstructure feature depth is greater than 100 μm, the polishing tool used is a cylindrical profiling tool. For rotating microstructure workpieces, variable gap polishing is used. When the microstructure feature depth is less than 100 μm, the polishing tool used is a conical tool. When the microstructure feature depth is greater than 100 μm, the polishing tool used is a conical column profiling tool. Then install the polishing tool;

[0017] F. Then pour the prepared shear thickening polishing liquid into the polishing liquid tank until the polishing liquid submerges the polishing surface.

[0018] G. Insert the heating rod into the upper layer of the polishing liquid, start the power of the polishing liquid temperature control system, set the polishing liquid temperature to between 40-50℃, and turn on the alternating power supply when the polishing liquid reaches the set temperature.

[0019] H. Start the polishing spindle and rotary table. The polishing spindle speed range is 800-900 r / min. The rotary table moves at a speed of 0.5-1 mm / s or rotates at 4-5 r / min to perform shear thickening non-contact polishing on the workpiece.

[0020] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0021] 1. The multi-field composite non-contact polishing device suitable for polishing the surface of high-precision complex parts constructed by the present invention can achieve high-efficiency and high-quality polishing of workpieces through the combination of temperature field, electric field, magnetic field, chemical field, and mechanical field. The temperature control system can achieve constant control of the temperature of the non-contact polishing liquid, ensuring that the polishing liquid always maintains a good shear thickening effect in a constant temperature field during the polishing process. The alternating power supply generates an electric field between the polishing tool and the workpiece. The polarized abrasive particles in the dielectric medium are subjected to the dielectrophoretic force to move, preventing the sedimentation of most of the abrasive particles during the polishing process and improving the polishing removal rate. A magnetic field is applied between the polishing tool and the workpiece to promote the adsorption of magnetic abrasive particles in the polishing liquid on the workpiece surface, allowing the abrasive particles to enter more corners of the complex surface of the workpiece and increase the pressure of the abrasive particles on the workpiece surface during polishing, thereby improving the polishing efficiency. The oxidant in the polishing liquid can chemically react with the workpiece surface to form a softer passivation layer, and the surface oxide layer is removed by the mechanical action of the abrasive particles. This cycle can eventually achieve a high-quality surface.

[0022] 2. This invention uses a non-contact polishing method, making it suitable for high-quality conformal polishing of various complex surface components, especially microstructured surfaces. This invention can be designed with different profiling tools to achieve non-contact polishing based on the complex surface of optical components, achieving sub-nanometer surface roughness while maintaining surface accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of a multi-field composite non-contact polishing device;

[0024] Figure 2 This is a processing flow chart of a multi-field composite non-contact polishing device;

[0025] Figure 3 This is a schematic diagram of micro-groove processing with a depth of less than 100 μm;

[0026] Figure 4 yes Figure 3 Schematic diagram of the workpiece.

[0027] Figure 5 yes Figure 5 AA cross-section of FIG (hatching not shown).

[0028] Figure 6 Schematic diagram of micro-groove profiling with a depth greater than 100 μm.

[0029] Figure 7 yes Figure 6 Axonometric drawing of .

[0030] Figure 8 This is a schematic diagram of ordinary polishing processing with a depth greater than 100 μm.

[0031] Figure 9 This is a comparison diagram of the pressure curves for micro-groove profiling with a depth greater than 100 μm and conventional polishing.

[0032] Figure 10 It is a schematic diagram of plane rectangular grating processing.

[0033] Figure 11 yes Figure 10 Axonometric drawing of .

[0034] In the figure: 1. Polishing liquid tank, 2. Heating rod, 3. Polishing tool, 4. Workpiece, 5. Alternating power supply, 6. Thermocouple, 7. Polishing liquid, 8. Magnet, 9. Rotating worktable, 10. Fixture. DETAILED DESCRIPTION

[0035] The following provides a clear and complete description of the principles and technical solutions of the present invention in conjunction with the following embodiments and accompanying drawings. The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the following embodiments, other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] like Figure 1-11 As shown, a multi-field composite non-contact polishing device includes a controller, a polishing liquid tank 1, a polishing liquid temperature control system, a polishing tool 3, an alternating power supply 5, a magnet 8, a turntable and a fixture 10.

[0037] The polishing liquid temperature control system includes a heating rod 2, a thermocouple 6, an external power supply and a controller. The heating rod 2 is placed on the upper layer of the polishing liquid 7, and the thermocouple 6 is installed on the inner wall of the polishing liquid tank 1 for real-time monitoring of the temperature of the polishing liquid 7 in the polishing liquid tank 1. The heating rod 2 and the thermocouple 6 are both connected to the power supply and the controller. The heating rod 2 manually starts the controller to heat the polishing liquid 7 as needed. The thermocouple 6 monitors the temperature of the polishing liquid 7 in the polishing liquid tank 1 in real time and transmits the analog-to-digital converted signal back to the controller. The controller controls whether the heating rod 2 continues to heat, thereby achieving precise control of the constant temperature of the polishing liquid 7 in the polishing liquid tank 1.

[0038] The fixture 10 fixes the workpiece 4 on the rotating worktable 9, and the polishing liquid 7 is poured into the polishing liquid tank 1 until it covers the inside of the gap between the polishing tool 3 and the workpiece 4. Under the high-speed rotation of the polishing tool 3 and the rotation of the workpiece 4, thickening occurs, thereby achieving shear removal of the surface material of the workpiece 4.

[0039] The positive and negative electrodes of the alternating power supply 5 are connected to the polishing tool 3 and the workpiece 4, respectively, so that an electric field is generated in the gap between the polishing tool 3 and the workpiece 4. Due to the polarization effect, the abrasive particles in the polishing liquid 7 are subjected to certain repulsive and attractive forces under the action of the electric field and move, so that most of the abrasive particles are distributed on the polishing surface of the polishing tool 3 and the processed surface of the workpiece 4, preventing the abrasive particles from settling.

[0040] The magnet 8 is fixed on the rotating workbench 9 and is located directly below the fixture 10, providing a magnetic field between the polishing tool 3 and the workpiece 4, so that the magnetic abrasive particles in the polishing liquid 7 are tightly adsorbed on the processed surface of the workpiece 4.

[0041] Furthermore, the polishing liquid 7 is a shear-thickening polishing liquid 7, comprising deionized water, polyhydroxy polymer particles, abrasive particles, an oxidizing agent, and a pH adjuster. The polyhydroxy polymer particles are present in a ratio of 35-45 wt%; the abrasive particles are silica with a particle size of 50 nm; magnetic abrasive particles are optionally added in a ratio of 15-25 wt%; the oxidizing agent is hydrogen peroxide at a ratio of 0.6%; the pH adjuster is citric acid, adjusted to a pH of 9; and the remainder is deionized water.

[0042] Furthermore, the polishing tool 3 includes a general polishing tool contour polishing tool wrapped with a damping polishing pad.

[0043] A multi-field composite non-contact polishing method, which uses a multi-field composite non-contact polishing device for polishing, comprises the following steps:

[0044] I. First, fix the workpiece 4 on the rotating worktable 9 using the fixture 10. Select different types of polishing tools 3 based on the shape and surface features of the workpiece 4: For parallel microstructure workpieces 4 with a micro-feature depth less than 100 μm, the polishing tool 3 used is a cylindrical tool. When the microstructure feature depth is greater than 100 μm, the polishing tool 3 used is a cylindrical profiling tool. For rotating microstructure workpieces 4, variable gap polishing is used. When the microstructure feature depth is less than 100 μm, the polishing tool 3 used is a conical tool. When the microstructure feature depth is greater than 100 μm, the polishing tool 3 used is a conical column profiling tool. Then, install the polishing tool 3.

[0045] J. Then pour the prepared shear thickening polishing liquid 7 into the polishing liquid tank 1 until the polishing liquid 7 submerges the polishing surface.

[0046] K. Insert the heating rod 2 into the upper layer of the polishing liquid 7, start the power supply of the polishing liquid temperature control system, set the temperature of the polishing liquid 7 to be controlled between 40-50°C, and turn on the alternating power supply 5 when the polishing liquid 7 reaches the set temperature.

[0047] L. Start the polishing spindle and the rotary table 9. The polishing spindle speed range is 800-900 r / min. The rotary table 9 moves at a speed of 0.5-1 mm / s or rotates at 4-5 r / min to perform shear thickening non-contact polishing on the workpiece 4.

[0048] The embodiments of the present invention are as follows: Embodiment 1: A parallel microstructure workpiece with a micro-feature depth of less than 100 μm, and a multi-field composite non-contact polishing device is constructed and attached to a five-axis motion platform.

[0049] like Figure 3-5 As shown in the figure, the steps for polishing a parallel microstructure workpiece with a micro-feature depth of less than 100 μm are as follows:

[0050] In the first step, the workpiece 4 is clamped and fixed on the rotary table 9 using the fixture 10 to ensure the flatness of the workpiece 4 on the rotary table 9. A cylindrical polishing tool 3 with a diameter of 20 mm is installed on the machine tool spindle, and the polishing gap between the cylindrical polishing tool 3 and the workpiece 4 is adjusted to 0.2 mm.

[0051] The second step is to prepare a non-contact shear-thickening polishing slurry with the following weight percentages: 20 wt% 50 nm SiO2 abrasive, 40 wt% polyol polymer, 0.6 wt% H2O2, and a pH of 9. The remainder is deionized water. All ingredients are ultrasonically mixed in the deionized water until uniformly mixed. The prepared shear-thickening polishing slurry is then poured into polishing tank 1.

[0052] The third step is to insert the heating rod 2 into the polishing liquid, and set the required temperature of the polishing liquid 7 on the controller of the polishing liquid temperature control system, and set the temperature to 45°C.

[0053] The fourth step is to start the machine tool spindle and the rotary table 9, adjust the spindle speed to 900 r / min, and reciprocate the rotary table 9 at a speed of 1 mm / s. At the same time, turn on the alternating power supply 5 to perform non-contact polishing on the micro groove with a depth of less than 100 μm.

[0054] Implementation Example 2: Parallel microstructure workpiece with microfeature depth greater than 100 μm.

[0055] like Figure 6-9 As shown, the polishing of a parallel microstructure workpiece with a microfeature depth greater than 100 μm differs from Example 1 in that the polishing tool 3 is a profiling tool, its axial length greater than or equal to the width of the workpiece 4, and its centerline is aligned with the side of the workpiece 4. The rotary table 9 reciprocates along the length of the workpiece 4 at a slow speed of 1 mm / s to ensure uniform coverage of the microstructure on the entire surface of the workpiece 4. The pressure exerted on the microstructure on the surface of the workpiece 4 shows that the pressure distribution on the microstructure on the surface of the workpiece 4 is more uniform when the profiling tool is used to polish microgrooves with a depth greater than 100 μm, compared to when the profiling tool is used to polish the microstructure with a conventional tool.

[0056] Implementation Example 3: Rotational microstructure workpiece with micro-feature depth less than 100 μm.

[0057] like Figure 10-11As shown, the polishing of a rotating microstructure workpiece with a microfeature depth of less than 100 μm is different from that of Example 1 in that the polishing tool 3 is a frustum-shaped polishing profiling tool, and variable gap polishing is adopted to avoid the problem of uneven material removal rate between the central part and the peripheral part of the rotating microstructure workpiece, thereby effectively ensuring the surface accuracy of the microstructure feature. The axial length of the polishing tool 3 is equal to the radius of the workpiece 4, and the rotary worktable 9 rotates at a speed of 5 r / min to ensure that the microstructure of the entire surface of the workpiece 4 can be evenly covered.

[0058] The basic principles, main features, and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are intended to illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A multi-field composite non-contact polishing device, characterized in that: It includes a controller, a polishing liquid tank (1), a polishing liquid temperature control system, a polishing tool (3), an alternating power supply (5), a magnet (8), a turntable and a fixture (10); The polishing liquid temperature control system comprises a heating rod (2), a thermocouple (6), an external power supply and a controller; the heating rod (2) is placed on the upper layer of the polishing liquid (7), and the thermocouple (6) is installed on the inner wall of the polishing liquid tank (1) for real-time monitoring of the temperature of the polishing liquid (7) in the polishing liquid tank (1); the heating rod (2) and the thermocouple (6) are both connected to the power supply and the controller; the heating rod (2) manually starts the controller to heat the polishing liquid (7) as needed, and the thermocouple (6) monitors the temperature of the polishing liquid (7) in the polishing liquid tank (1) in real time and transmits the analog-to-digital converted signal back to the controller, and the controller controls whether the heating rod (2) continues to heat, thereby achieving precise control of the constant temperature of the polishing liquid (7) in the polishing liquid tank (1); The fixture (10) fixes the workpiece (4) on the rotating worktable (9), and the polishing liquid (7) is poured into the polishing liquid tank (1) until it covers the gap between the polishing tool (3) and the workpiece (4). The polishing liquid thickens under the high-speed rotation of the polishing tool (3) and the rotation of the workpiece (4), thereby achieving shear removal of the surface material of the workpiece (4); The positive and negative electrodes of the alternating power supply (5) are respectively connected to the polishing tool (3) and the workpiece (4), so that an electric field is generated in the gap between the polishing tool (3) and the workpiece (4). Due to the polarization effect, the abrasive particles in the polishing liquid (7) are subjected to a certain repulsive force and attractive force under the action of the electric field and move, so that most of the abrasive particles are distributed on the polishing surface of the polishing tool (3) and the processed surface of the workpiece (4), thereby preventing the abrasive particles from settling; The magnet (8) is fixed on the rotating workbench (9) and is located directly below the fixture (10), providing a magnetic field between the polishing tool (3) and the workpiece (4), so that the magnetic abrasive particles in the polishing liquid (7) are tightly adsorbed on the processed surface of the workpiece (4).

2. The multi-field composite non-contact polishing device according to claim 1, characterized in that: The polishing liquid (7) is a shear thickening polishing liquid (7), comprising deionized water, polyhydroxy polymer particles, abrasive particles, an oxidant, and a pH regulator; the polyhydroxy polymer particles are selected from 35-45 wt%; the abrasive particles are selected from silicon dioxide, with a particle size of 50 nm; magnetic abrasive particles are selected from the addition, with an abrasive particle ratio of 15-25 wt%; the oxidant is selected from hydrogen peroxide, with a ratio of 0.6%; the pH agent is selected from citric acid, and the pH value is adjusted to 9, and the rest are deionized water.

3. The multi-field composite non-contact polishing device according to claim 1, characterized in that: The polishing tool (3) includes a general polishing tool wrapped with a damping polishing pad and a contour polishing tool.

4. A multi-field composite non-contact polishing method, characterized in that: Polishing is performed using the multi-field composite non-contact polishing device according to claim 1, comprising the following steps: A. First, fix the workpiece (4) on the rotating worktable (9) through the fixture (10), and select different types of polishing tools (3) according to the shape and surface feature morphology of the workpiece (4): for the parallel microstructure workpiece (4) and when the microfeature depth is less than 100 μm, the polishing tool (3) used is a cylindrical tool; when the microstructure feature depth is greater than 100 μm, the polishing tool (3) used is a cylindrical profiling tool; for the rotating microstructure workpiece (4), variable gap polishing is used, when the microstructure feature depth is less than 100 μm, the polishing tool (3) used is a conical tool; when the microstructure feature depth is greater than 100 μm, the polishing tool (3) used is a conical column profiling tool; then the polishing tool (3) is installed; B. Then, pour the prepared shear thickening polishing liquid (7) into the polishing liquid tank (1) until the polishing liquid (7) submerges the polishing surface; C. Insert the heating rod (2) into the upper layer of the polishing liquid (7), start the power supply of the polishing liquid temperature control system, set the temperature of the polishing liquid (7) to be controlled between 40-50°C, and turn on the alternating power supply (5) when the polishing liquid (7) reaches the set temperature; D. Start the polishing spindle and the rotary table (9), the polishing spindle speed range is 800-900 r / min, and the rotary table (9) moves horizontally at a speed of 0.5-1 mm / s or rotates at a speed of 4-5 r / min to perform shear thickening non-contact polishing on the workpiece (4).

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