Air pressure regulated and controlled film medium shaping super-smooth processing device and processing method

Abstract

The invention discloses an air-pressure-regulated film medium shaping and ultra-smooth machining device and method. A lower driving module of the machining device comprises a platform driving motor, a polishing platform, a pneumatic suction cup and a film medium from bottom to top, and an auxiliary device of the pneumatic suction cup comprises a vacuum generator, a filter, a gas flow meter and a reversing valve. An upper driving module of the machining device comprises a driving motor, a base, a buffer medium and a to-be-polished element from top to bottom. The method has the advantages of being low in cost and easy to operate, modification polishing and ultra-smooth treatment of the element are completed under specific parameters based on regulation and control distribution of the contact pressure intensity of the film medium on the element and the catalytic reaction of the film medium, surface damage is not caused, and finally the damage-free ultra-smooth optical element is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of precision machining of optical elements, and in particular to a film medium shaping, polishing and ultra-smooth machining device and machining method based on air pressure regulation, which realizes high-precision, ultra-smooth and damage-free manufacturing of optical elements, in particular optical glass and semiconductor elements. Background Art

[0002] With the advancement of optical processing technology, the requirements for optical systems and optical components in fields such as laser fusion, space communication, precision lithography and precision guidance are gradually increasing, requiring optical components to have nanometer-level surface accuracy, picometer-level ultra-smooth surfaces and near-defect-free surface quality.

[0003] Current methods for achieving high-precision, ultra-smooth surfaces on optical components include chemical mechanical polishing, magnetorheological polishing, ion beam polishing, and airbag polishing. Chemical mechanical polishing involves material removal through the plowing and grinding action of hard particles under a certain pressure. Ultra-smooth polishing can be achieved to a certain extent by adjusting polishing parameters and using nano-abrasives. However, nano-abrasives are expensive, prone to agglomeration, and require complex control. Furthermore, their high hardness inevitably creates scratches, pits, and other damage on the component surface. Magnetorheological polishing and ion beam polishing equipment are expensive, and post-processing can lead to problems such as iron powder residue and ion implantation, further impacting component surface quality. Airbag polishing utilizes a single, uniform pressure distribution, resulting in insufficient medium deformation adaptability and significant edge effects.

[0004] US10199242 discloses a polishing pad coated with a platinum film for processing silicon carbide components, achieving a surface roughness of 0.228 nm. However, the cost of platinum film coating the polishing pad is high, and the platinum residue on the surface of the optical component is difficult to completely remove, and the method does not involve the reshaping and polishing of the component. CN119238385A discloses a polishing disk and its preparation method, which embeds metal nanoparticles in a hot-melt material to achieve a sub-angstrom surface. However, metal nanoparticles are prone to agglomeration to form large particles, causing particle scratches, and it is difficult to control the uniform distribution of particles in the hot-melt material. The solution also does not address how to perform reshaping and polishing of the component. CN102873648A discloses a partitioned air cushion polishing disk with different polishing pressures in different areas controlled by an inflatable membrane. The method realizes independent control of the pressure of the multi-partition polishing pad and realizes the shaping of the partitioned pressure regulation, overcoming the problem of insufficient or excessive polishing of some areas caused by a single structure. However, the polishing pad in this solution is a polishing fabric or sandpaper, and uses granular abrasives, which may introduce damage such as scratches, and does not mention the roughness of the component, so an ultra-smooth surface cannot be obtained.

[0005] Therefore, there is an urgent need to propose a processing method that can achieve low-cost, high-precision shaping and polishing, ultra-smooth processing and damage-free processing of optical components to meet the growing high-end application needs of optical components. Summary of the Invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to propose a film medium shaping, polishing and ultra-smooth processing device and processing method based on air pressure regulation. Based on the deformation amplitude of the film medium regulated by air pressure, the shaping and polishing of the component is completed by controlling the contact pressure distribution between the film medium and the component, thereby obtaining nanometer-level surface accuracy; furthermore, the film medium itself acts as a catalyst, and material removal is achieved through its catalytic chemical reaction with the optical component material, thereby avoiding the problems of pits, scratches, iron powder residue and ion injection caused by the existing polishing method, and obtaining a picometer-level ultra-smooth surface. The present invention has the characteristics of low cost, simple operation, safety and reliability, and obtains high-precision, ultra-smooth and damage-free optical components through the shaping, polishing and ultra-smooth processing of the film medium regulated by air pressure.

[0007] The technical solutions of the present invention are as follows:

[0008] A pressure-controlled membrane media shaping and ultra-smoothing processing device is characterized in that it includes a lower drive module, an upper drive module, an auxiliary device and a polishing solution supply system, wherein:

[0009] The lower driving module includes, from bottom to top:

[0010] The platform drive motor has an output shaft rigidly connected to the center of the polishing platform through a coupling;

[0011] Polishing platform, the upper surface of which is fixed with pneumatic suction cup by bolts;

[0012] The pneumatic suction cup is an annular disc with multiple concentric ring partitions on the upper surface. Multiple micro-holes are evenly distributed in each partition ring. Each partition is connected to the auxiliary device through an independent air pipe.

[0013] The membrane medium is flatly adhered to the upper surface of the pneumatic suction cup by negative pressure adsorption;

[0014] The upper drive module includes, from top to bottom:

[0015] The base drive motor has an output shaft coaxially connected to the top center of the base through a flange;

[0016] The base, the cylinder, and the bottom are fixedly connected to the buffer medium by gluing;

[0017] A buffer medium, the lower surface of which holds the component to be polished by vacuum adsorption;

[0018] The auxiliary device comprises:

[0019] A vacuum generator connected to the air intake manifold of the pneumatic suction cup through a main air pipe;

[0020] Gas flowmeter, installed on each branch gas pipe, is used to control the gas pressure;

[0021] The reversing valve is installed at the end of each branch air pipe to switch between the suction and blowing modes;

[0022] The polishing solution supply system has a liquid drop nozzle located above the contact interface between the membrane medium and the element to be polished.

[0023] The polishing platform is used to carry the pneumatic suction cup and the membrane medium, and is made of stainless steel or aluminum with a flatness of ≤50μm; the surface flatness of the pneumatic suction cup is ≤10μm, and the pneumatic suction cup is made of aluminum oxide or silicon carbide.

[0024] The surface of the pneumatic suction cup is divided into n partitions according to the radius, where n is 3 to 10, and the radius of each partition is represented by R i (i=1,…,n), each partition is provided with micropores in the annular zone, the diameter of the micropores ranges from 100μm to 1mm, and the number of micropores in each partition does not exceed (R i 2 -R i-1 2 ) / 2,(i=2,…,n).

[0025] The membrane medium is a layer of metal sheet / foil attached to the surface of the pneumatic suction cup. The metal is a transition metal of Groups VIIB, VIII and IB, including nickel, ruthenium, manganese and copper, and has a purity of not less than 99.9%. The thickness of the membrane medium is 0.01 to 0.05 mm.

[0026] The polishing solution comprises a polishing solvent, wherein the polishing solvent is deionized water, and the resistivity is greater than or equal to 15 MΩ·cm.

[0027] The base material of the upper drive module is stainless steel, aluminum, etc. The upper part of the base is fixedly coaxially connected to the drive motor, and the buffer medium is fixedly connected to the lower surface of the base. The buffer medium is made of polyurethane, damping cloth, non-woven fabric or sponge.

[0028] A method for shaping and ultra-smoothing a membrane medium by regulating air pressure is characterized by comprising:

[0029] Shaping and polishing stage:

[0030] Fix the component to be polished on the lower surface of the buffer medium and apply a load pressure of 15 to 40 kPa;

[0031] Add the polishing solution dropwise to the contact interface between the component to be polished and the membrane medium at a dropping rate of 1 to 10 ml / min;

[0032] Start the platform drive motor and the base drive motor, and control the speed of the polishing platform and the component to be polished to 50-80 rpm;

[0033] The air pressure and airflow direction of each partition of the pneumatic suction cup are adjusted by auxiliary devices to make the deformation variable δ of the membrane medium conjugate with the surface error of the component. The formula of the deformation variable δ of the membrane medium is as follows:

[0034]

[0035] Wherein, ΔP is the pressure difference on both sides of the membrane medium, R is the micropore radius, E is the elastic modulus of the membrane medium material, ν is the Poisson's ratio of the membrane medium material, and D is the bending stiffness of the membrane medium;

[0036] Dynamically adjust the air pressure and continuously shape and polish until the RMS value of the component surface is ≤10nm;

[0037] Ultra-smooth processing stage:

[0038] Reduce the load pressure to 10-20 kPa and adjust the polishing solution dripping rate to 1-5 ml / min;

[0039] Control the rotation speed of the component to be polished and the polishing platform to 10-30 rpm, and make the component perform eccentric reciprocating motion of 10-25 mm along the radial direction of the pneumatic suction cup;

[0040] Set all zones of the pneumatic suction cup to uniform suction with an air pressure of 0.01-0.02 MPa, and use the catalytic effect of the membrane medium to achieve atomic-level material removal;

[0041] Continue polishing until the root mean square value of the component surface roughness is ≤0.1nm.

[0042] The air pressure-regulated membrane medium shaping and ultra-smooth processing method is characterized in that, during the shaping and polishing stage, the zoned air pressure control of the pneumatic suction cup is specifically as follows: the suction pressure is set to 0.015 to 0.03 MPa for the zone corresponding to the concave area of ​​the component surface, and the blowing pressure is set to 0.03 to 0.05 MPa for the zone corresponding to the convex area of ​​the component surface.

[0043] The air pressure-regulated membrane medium shaping and ultra-smooth processing method is characterized in that when the membrane medium is nickel foil, 5wt% hydrogen peroxide is added to the polishing solution and the pH value is adjusted to 3-5.

[0044] An optical element is processed by the above method, and its surface shape root mean square value is ≤10nm, the roughness root mean square value is ≤0.1nm, and there is no scratch or pit damage.

[0045] Compared with the prior art, the technical effects of the present invention are as follows:

[0046] 1) Based on the air pressure, the deformation direction and pressure magnitude of the membrane medium are regulated, and the contact pressure distribution between the membrane medium and the optical element is controlled to obtain nanometer-level surface accuracy.

[0047] 2) The film dielectric (metal sheets / foils such as nickel, ruthenium, and copper) is a soft material with a hardness lower than that of the component being polished (such as fused quartz or silicon carbide), preventing scratches or pits on the component surface. This ensures that the processed optical component has an intact surface and lattice structure.

[0048] 3) The film medium (metal sheets / foils such as nickel, ruthenium and copper) acts as a catalyst. Through the interaction between catalyst atoms and component atoms, an ultra-smooth surface of the optical component at the picometer level is obtained, overcoming the form of precious metal coating in existing technologies and greatly reducing processing costs.

[0049] 4) By controlling the pressure (direction, size) of the membrane medium and the processing parameters (load pressure, rotation speed, polishing time, and type and concentration of the catalyst), a set of devices is used to achieve both shaping and polishing and ultra-smooth processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the membrane medium shaping and ultra-smoothing processing device regulated by air pressure of the present invention.

[0051] Figure 2 Schematic diagram and partial enlarged view of the air pressure-regulated membrane medium shaping and ultra-smoothing processing device of the present invention.

[0052] Figure 3 Schematic diagram of the undulating deformation of the membrane medium under the action of the pneumatic suction cup in the present invention.

[0053] In the figure: 1-polishing platform, 11-platform drive motor, 2-pneumatic suction cup, 21-micropore, 3-membrane medium, 31-membrane medium protrusion, 32-membrane medium concave, 4-component to be polished. 5-buffer medium, 6-base, 61-base drive motor, 7-polishing solution DETAILED DESCRIPTION

[0054] The present invention will be further described below with reference to the following examples, but the scope of the present invention should not be limited thereto.

[0055] See Figure 1 , Figure 1 The schematic diagram of the air pressure-controlled membrane medium shaping and ultra-smoothing processing device of the present invention is shown in the figure, including:

[0056] Lower driver module:

[0057] Polishing platform 1: driven by a motor to rotate (50-80 rpm), carrying the pneumatic suction cup 2 and the film medium 3.

[0058] Pneumatic suction cup 2: The surface is divided into 3 to 10 independent zones, each zone is provided with micropores 21 (diameter 100 μm to 1 mm), and the air pressure of each zone (0.01 to 0.1 MPa) is regulated by a vacuum generator, a flow meter and a reversing valve to achieve suction or blowing.

[0059] Membrane medium 3: high-purity (≥99.9%) transition metal foil (such as nickel, ruthenium, copper), thickness 0.01 to 0.05 mm, with both flexibility and catalytic activity.

[0060] Upper drive module:

[0061] Base 6 and buffer medium 5: fix the element to be polished 4 (such as fused quartz) and evenly transmit the load pressure (10-40 kPa) through buffer materials such as polyurethane.

[0062] Polishing solution 7: Deionized water (resistivity ≥ 15 MΩ·cm) with the addition of an oxidant (such as HO) or a pH adjuster (oxalic acid, ammonia, etc.).

[0063] In this embodiment, the diameter A method for shaping and ultra-smoothing a 5mm thick fused quartz component was proposed. This method uses zoned air pressure to control the membrane's morphology, combined with specific process parameters, to achieve high-precision, damage-free, ultra-smooth surface processing. The specific implementation steps are as follows:

[0064] Phase 1: Processing equipment and material preparation

[0065] Polishing platform: Choose an aluminum polishing platform with a diameter of 200mm and a surface flatness of less than 20μm to ensure stability during the processing.

[0066] Pneumatic suction cup: A pneumatic suction cup made of silicon carbide is selected with a surface flatness of 10μm. The surface of the pneumatic suction cup is divided into five zones, and the radius of each zone is represented as R1, R2…, R5. Micropores are set in the annular zone of each zone. The diameter of the micropores ranges from 100μm. The number of micropores in each zone is 300 to 400, which are used to accurately control the air pressure.

[0067] Drive system: Both the upper drive module and the lower drive module use servo motors to achieve precise speed and position control.

[0068] Components to be polished: Made of fused quartz.

[0069] Buffer medium: Polyurethane material is selected to protect the surface of the component during the polishing process to avoid scratches.

[0070] Membrane medium: nickel foil with a diameter of 200 mm, a thickness of 20 μm, and a purity of ≥99.99%.

[0071] Polishing solution: Deionized water with a resistivity of 15 MΩ·cm.

[0072] The second stage: shaping and polishing

[0073] Assembly: First, secure the pneumatic chuck to the polishing platform, then secure a complete nickel foil film to the pneumatic chuck. Secure the fused silica element to be shaped and polished to the bottom surface of the buffer medium, and apply a load pressure of 25kPa to the top surface of the optical element through the load device.

[0074] Polishing solution addition: Add polishing solution to the interface between the membrane medium and the element at a rate of 5 to 10 ml / min.

[0075] Start polishing: Set the component speed to 65 rpm and the polishing disc speed to 60 rpm. The polishing platform and fused quartz component rotate in a counterclockwise direction.

[0076] Air pressure control: Based on the surface error data between the input surface shape of the component and the designed surface shape, the initial pressure combination of each partition is generated. Through microporous air pressure control, the membrane medium presents a morphology conjugate with the error distribution. Specifically, through the pneumatic suction cup auxiliary device, the 1st, 3rd, and 4th partitions of the suction cup are set to suction with a pressure of 0.03MPa, and the 2nd and 5th partitions of the suction cup are set to blowing with a pressure of 0.025MPa. The component surface shape is checked every 10 minutes and the air pressure is adjusted. Low-frequency undulating surface errors are corrected first, and then high-frequency error processing (ultra-smoothing processing) is switched to.

[0077] Stage 3: Ultra-smooth treatment

[0078] Reassembly: Re-fix the pneumatic chuck to the polishing platform and secure a complete nickel film to the pneumatic chuck. Secure the fused quartz element to be shaped and polished to the bottom surface of the buffer medium and apply a load pressure of 15kPa to the top surface of the optical element.

[0079] Polishing solution addition: Add polishing solution to the interface between the membrane medium and the component at a rate of 1 to 5 ml / min.

[0080] Start polishing: Start the polishing machine, the component speed is 30rpm, the polishing disc speed is 25rpm, the polishing platform rotates counterclockwise around the center, and the fused quartz component rotates while also reciprocating along the radial eccentric distance of 10 to 25mm of the pneumatic suction cup to achieve ultra-smooth processing.

[0081] Air pressure maintenance: The direction of the air pressure at each micropore in different radius zones on the surface of the pneumatic suction cup remains the same, at a size of 0.015MPa, for ultra-smooth processing.

[0082] Phase 4: Testing and Evaluation

[0083] After polishing for a certain period of time, the fused quartz component is removed for cleaning, and the surface shape and roughness are tested using a laser interferometer and an atomic force microscope respectively. When the root mean square value of the surface shape of the fused quartz component is better than 10nm, and when the root mean square value of the roughness of the fused quartz component is better than 0.1nm, high-precision ultra-smooth processing is completed.

[0084] The test results of the laser interferometer show that the root mean square value of the fused quartz element surface shape in the area of ​​φ30mm is 9.3nm. The test results of the atomic force microscope show that the surface shape of the fused quartz element is 1×1μm. 2 Within the test range, the RMS value of the fused quartz component surface roughness was 0.066nm. Since nickel is less hard than fused quartz, no scratches are produced on the surface of the fused quartz component, thus obtaining a high-precision, ultra-smooth, damage-free fused quartz surface.

[0085] This embodiment solves the contradiction between precision, damage and cost in optical component processing by dynamically controlling the deformation of the membrane medium with air pressure and performing catalytic reaction polishing, thus providing an innovative solution for high-end optical manufacturing.

[0086] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, including but not limited to the material, shape and size of the sample. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A membrane medium shaping and ultra-smoothing processing device controlled by air pressure, characterized in that: It includes a lower driving module, an upper driving module, an auxiliary device and a polishing solution supply system, wherein: The lower driving module includes, from bottom to top: A platform drive motor (11), the output shaft of which is rigidly connected to the center of the polishing platform (1) through a coupling; A polishing platform (1), the upper surface of which is fixedly connected to a pneumatic suction cup (2) via bolts; The pneumatic suction cup (2) is an annular disc body, and a plurality of concentric ring partitions are provided on the upper surface. A plurality of micro holes (21) are evenly distributed in the ring of each partition, and each partition is connected to the auxiliary device through an independent air pipe; The membrane medium (3) is flatly attached to the upper surface of the pneumatic suction cup (2) by negative pressure adsorption; The upper drive module includes, from top to bottom: A base drive motor (61) whose output shaft is coaxially connected to the top center of the base (6) through a flange; The base (6) is cylindrical, and the bottom is fixedly connected to the buffer medium (5) by gluing; The buffer medium (5) has a lower surface that fixes the element to be polished (4) by vacuum adsorption or bonding; the auxiliary device includes: A vacuum generator connected to the air intake manifold of the pneumatic suction cup (2) via a main air pipe; Gas flowmeter, installed on each branch gas pipe, is used to control the gas pressure; The reversing valve is installed at the end of each branch air pipe to switch between the suction and blowing modes; The polishing solution supply system has a liquid drop nozzle located above the contact interface between the membrane medium (3) and the element to be polished (4).

2. The air pressure controlled membrane medium shaping and ultra-smoothing and processing device according to claim 1 is characterized in that: The polishing platform is used to carry the pneumatic suction cup and the membrane medium, and is made of stainless steel or aluminum with a flatness of ≤50μm; the surface flatness of the pneumatic suction cup is ≤10μm, and the pneumatic suction cup is made of aluminum oxide or silicon carbide.

3. The air pressure controlled membrane medium shaping, super-smoothing and processing device according to claim 1 or 2, characterized in that: The surface of the pneumatic suction cup is divided into n partitions according to the radius, where n is 3 to 10, and the radius of each partition is represented by R i (i=1,…,n), each partition is provided with micropores in the annular zone, the diameter of the micropores ranges from 100μm to 1mm, and the number of micropores in each partition does not exceed (R i 2 -R i-1 2 ) / 2,(i=2,…,n).

4. The air pressure controlled membrane medium shaping and ultra-smoothing processing device according to claim 1, characterized in that: The membrane medium is a layer of metal sheet / foil attached to the surface of the pneumatic suction cup. The metal is a transition metal of Groups VIIB, VIII and IB, including nickel, ruthenium, manganese and copper, and has a purity of not less than 99.9%. The thickness of the membrane medium is 0.01 to 0.05 mm.

5. The air pressure controlled membrane medium shaping and ultra-smoothing processing device according to claim 1, characterized in that: The polishing solution comprises a polishing solvent, wherein the polishing solvent is deionized water, and the resistivity is greater than or equal to 15 MΩ·cm.

6. The air pressure controlled membrane medium shaping and super-smoothing processing device according to claim 1, characterized in that: The base material of the upper drive module is stainless steel, aluminum, etc. The upper part of the base is fixedly coaxially connected to the drive motor, and the buffer medium is fixedly connected to the lower surface of the base. The buffer medium is made of polyurethane, damping cloth, non-woven fabric or sponge.

7. A membrane medium shaping and ultra-smoothing processing method based on air pressure control of the processing device according to any one of claims 1 to 6, characterized in that: include: Shaping and polishing stage: Fix the component to be polished on the lower surface of the buffer medium and apply a load pressure of 15 to 40 kPa; Add the polishing solution dropwise to the contact interface between the component to be polished and the membrane medium at a dropping rate of 1 to 10 ml / min; Starting the platform drive motor (11) and the base drive motor (61), and controlling the rotation speed of the polishing platform (1) and the component to be polished (4) to be 50 to 80 rpm; The air pressure and airflow direction of each partition of the pneumatic suction cup (2) are adjusted by an auxiliary device so that the deformation variable δ of the membrane medium is conjugately matched with the surface error of the component. The formula of the deformation variable δ of the membrane medium is as follows: Wherein, ΔP is the pressure difference on both sides of the membrane medium, R is the micropore radius, E is the elastic modulus of the membrane medium material, ν is the Poisson's ratio of the membrane medium material, and D is the bending stiffness of the membrane medium; Dynamically adjust the air pressure and continuously shape and polish until the RMS value of the component surface is ≤10nm; Ultra-smooth processing stage: Reduce the load pressure to 10-20 kPa and adjust the polishing solution dripping rate to 1-5 ml / min; The rotation speed of the component to be polished (4) and the polishing platform (1) is controlled to be 10 to 30 rpm, and the component is made to perform an eccentric reciprocating motion of 10 to 25 mm along the radial direction of the pneumatic suction cup; All zones of the pneumatic suction cup are set to uniform suction with an air pressure of 0.01 to 0.02 MPa, and the catalytic effect of the membrane medium (3) is used to achieve atomic-level material removal; Continue polishing until the root mean square value of the component surface roughness is ≤0.1nm.

8. The air pressure controlled membrane medium shaping and ultra-smoothing processing method according to claim 7, characterized in that: During the shaping and polishing stage, the air pressure of the pneumatic suction cup (2) is specifically regulated as follows: the suction pressure of the corresponding zone of the concave area of ​​the component surface is set to 0.015-0.03 MPa, and the blowing pressure of the corresponding zone of the convex area of ​​the component surface is set to 0.03-0.05 MPa.

9. The air pressure controlled membrane medium shaping and ultra-smoothing processing method according to claim 7, characterized in that: When the membrane medium (3) is nickel foil, 5 wt% hydrogen peroxide is added to the polishing solution (7), and the pH value is adjusted to 3-5.

10. An optical element, characterized in that: The surface is processed by the method according to any one of claims 7 to 9, and the root mean square value of the surface shape is ≤10nm, the root mean square value of the roughness is ≤0.1nm, and there is no scratch or pit damage.

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