A method for milling and grinding a convex step of a lens

Abstract

The present application belongs to the field of optical processing, and discloses a kind of milling and grinding method of convex surface step piece of lens. Including the following steps: (1) coarse grinding debugging, calculate the planned clear aperture;(2) if the planned clear aperture = finished lens clear aperture, then coarse grinding debugging is completed;If the planned clear aperture ≠ finished lens clear aperture, then repeat step (1), until the planned clear aperture = finished lens clear aperture;(3) fine grinding debugging, calculate the planned clear aperture;(4) if the planned clear aperture = finished lens clear aperture, then fine grinding debugging is completed;If the planned clear aperture ≠ finished lens clear aperture, then repeat step (3), until the planned clear aperture = finished lens clear aperture;(5) formal processing, get finished lens.The present application is suitable for the processing of step piece of hard material such as aspherical surface, spherical surface and silicon, and has high production efficiency, low cost and high precision.

Description

Technical Field

[0001] This invention belongs to the field of optical processing, and specifically relates to a milling method for a convex stepped surface of a lens. Background Technology

[0002] Most infrared optical lenses with convex stepped surfaces are machined using CNC lathes. CNC lathes typically machine softer materials such as germanium, zinc sulfide, zinc selenide, and chalcogenide glass. If the workpiece is made of hard materials like silicon, the machining cost of CNC lathe machining increases dramatically, resulting in low efficiency and poor process quality. Specifically: (1) CNC turning usually uses diamond turning tools, each costing 1,000 to 2,000 yuan. Turning a silicon convex step wafer requires 2 to 3 diamond turning tools, which is costly.

[0003] (2) Silicon is hard and the turning speed is slow. It takes 2 to 3 hours to process each silicon convex step wafer, which is time-consuming.

[0004] (3) Regarding such Figure 3 The blank lenses shown are currently being produced using methods such as... Figure 1 The milling process for convex stepped surfaces shown describes a process where a grinding wheel rotates around its axis while remaining vertical. The edge of the grinding wheel cuts the convex stepped surface, while the blank mirror simultaneously rotates around its axis. The grinding wheel moves clockwise from point A to point E relative to the blank mirror, precisely cutting the convex and stepped surfaces at point E. This process has the following problems: Figure 2 As shown, the grinding wheel used in workshop production cannot always maintain a good arc angle. Therefore, the same grinding wheel edge point is not used when cutting each spiral of the lens. This will result in a poor convex surface profile after machining and will produce obvious cutting marks. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a low-cost, high-efficiency and high-performance method for milling convex step surfaces of lenses.

[0006] To achieve the objectives of this invention, the specific technical solution is as follows: A milling method for a convex stepped lens includes the following steps: (1) Rough grinding and adjustment: The grinding wheel rotates around its axis of rotation to perform rough grinding on the lens. The rough grinding starts at the top of the lens and is performed vertically at the starting point. After the vertical cutting is completed, a platform is formed by cutting from the starting point in a spiral pattern. During the cutting process, the angle between the line connecting the center of the lens to the cutting point of the grinding wheel and the center of rotation of the grinding wheel is α. R is the curvature of the finished lens, and the cut aperture D2 is 94%~97% of the finished lens aperture D; After rough grinding and adjustment, measure the distance from the highest point of the convex surface of the lens to the step, set it as the convex surface sag, and calculate the actual light transmission diameter D3. The calculated optical aperture is D2+D-D3; (2) If the planned light transmission diameter D2+D-D3 = the finished lens light transmission diameter D, then the rough grinding and adjustment is completed; if the planned light transmission diameter D2+D-D3 ≠ the finished lens light transmission diameter D, then repeat step (1) until the planned light transmission diameter D2+D-D3 = the finished lens light transmission diameter D. After the rough grinding test is completed, save the tested rough grinding program and proceed with the fine grinding test. (3) Fine grinding and adjustment: Maintaining a cutting angle of α, the grinding wheel rotates around its axis to finely grind the lens. The fine grinding begins at the step, with vertical cutting performed first. After the vertical cutting is completed, a spiral cut is made from the starting point to the top of the lens to form a convex stepped piece. The light transmission diameter D4 of the cut is 97% to 99% of the light transmission diameter D of the finished lens. After fine grinding and adjustment, the distance from the highest point of the convex surface to the step is measured as the convex surface sag, and the actual light transmission diameter D5 is calculated. The calculated optical aperture is D4+D-D5; (4) If the planned light transmission diameter D4+D-D5 = the finished lens light transmission diameter D, then the fine grinding and adjustment is completed; if the planned light transmission diameter D4+D-D5 ≠ the finished lens light transmission diameter D, then repeat step (3) until the planned light transmission diameter D4+D-D5 = the finished lens light transmission diameter D. After the fine grinding and debugging are completed, save the debugged fine grinding program and proceed with the formal processing; (5) Formal processing: Run the debugged rough grinding program to begin processing; After the rough grinding program is completed, run the fine grinding program that has been debugged, input the center thickness of the lens to be equal to the center thickness of the finished product, and start processing to obtain the finished lens.

[0007] Furthermore, in step (1), a bronze grinding wheel is selected; Preferably, the grit size of the grinding wheel is 200 mesh to 100 mesh; Preferably, the parallelism of the bottom of the grinding wheel is less than 0.01 mm; Preferably, the radius of the fillet of the grinding wheel is less than 0.5 mm.

[0008] Furthermore, in step (1), the helical pitch is 0.01~0.03mm, and the selection of the helical linear velocity needs to ensure that the rotational speed of the lens is less than 1000 RPM when cutting the center part of the lens; Preferably, when the grinding wheel cuts the middle part of the lens, the lens rotation speed is the maximum. Within the lens radius range of 0 to n1%, the lens rotation speed decreases to 60% to 40% of the rotation speed of the middle part; within the lens radius range of n1% to n2%, the lens rotation speed decreases to 40% to 10%, 10≤n1≤20, 10≤n2≤100. Further, in step (1), the grinding wheel is raised first during cutting, and the first cut is made. If the first cut does not reach the center of the blank lens, the next cut is made until the center of the blank lens is reached. Then the center thickness of the lens is measured, and the theoretical center thickness of the machine tool is corrected and matched with the actual center thickness. The correction matching specifically involves comparing the actual measured center thickness of the lens with the theoretical center thickness of the lens, calculating the difference, and then using this difference to compensate for the tool dimensions of the machine tool.

[0009] Furthermore, in step (1), the starting point position is first subjected to vertical cutting, and the cutting is performed vertically downward at a speed of 0.05~0.1mm / min.

[0010] Furthermore, in step (1), before rough grinding and adjustment, a pre-rough grinding and adjustment is performed: The grinding wheel rotates around its axis of rotation to perform rough grinding on the lens. The rough grinding starts at the top of the lens and is performed vertically at the starting point. After the vertical cutting is completed, a platform is formed by cutting from the starting point in a spiral pattern. During the cutting process, the angle between the line connecting the center of the lens to the cutting point of the grinding wheel and the center of rotation of the grinding wheel is α. R is the curvature of the finished lens, and the cut aperture D1 is 40% to 60% of the aperture D of the finished lens.

[0011] Furthermore, in step (3), a bronze grinding wheel is selected.

[0012] Preferably, the grit size of the grinding wheel is 800 mesh to 400 mesh.

[0013] Preferably, the parallelism of the bottom of the grinding wheel is less than 0.01 mm.

[0014] Preferably, the radius of the fillet of the grinding wheel is less than 0.5 mm.

[0015] Furthermore, in step (3), during fine grinding and adjustment, the safety distance is first moved vertically downward from the starting point of fine grinding, and then the cutting platform is moved to the left or right at 0.03~0.05mm / min, and then downward at 0.03~0.05mm / min. After the platform is cut, it is cut to the top of the lens in a spiral form to process the entire convex step sheet.

[0016] Furthermore, in step (3), the helix pitch is 0.04~0.06mm.

[0017] Furthermore, in step (3), the surface roughness of the lens after fine grinding is less than or equal to 0.5 μm.

[0018] Furthermore, in step (2), the center thickness of the lens after rough grinding and adjustment is controlled to be 0.1~0.15mm larger than the center thickness of the finished lens.

[0019] Furthermore, in step (4), after fine grinding and adjustment, the center thickness is controlled to be 0.05~0.1mm larger than the center thickness of the finished product.

[0020] Furthermore, in step (5), the well-tuned rough grinding program is run, and the input lens center thickness is 0.05~0.1mm larger than the finished product center thickness.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The milling method for convex stepped lenses of the present invention is simple to operate and is applicable to the processing of stepped lenses made of aspherical, spherical, and hard materials such as silicon. It has high processing efficiency, low cost and high precision. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This refers to the existing milling method for convex stepped plates.

[0023] Figure 2 This is an enlarged schematic diagram of the existing milling method for convex stepped surfaces.

[0024] Figure 3 This is a schematic diagram of a blank lens.

[0025] Figure 4 This is a schematic diagram of the first round of rough grinding and debugging of the milling method for convex stepped plates of the present invention.

[0026] Figure 5 This is a schematic diagram of the second round of rough grinding debugging of the milling method for convex stepped plates of the present invention.

[0027] Figure 6 This is a schematic diagram of the fine grinding and debugging process of the milling method for convex stepped plates according to the present invention.

[0028] Figure 7 This is a schematic diagram illustrating the formal machining process of the milling method for convex stepped sheets according to the present invention. Detailed Implementation

[0029] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0030] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0032] Example 1 This embodiment provides a milling method for a convex stepped lens, involving a blank lens such as... Figure 3 As shown, the blank lens needs to be made spherical. When making the blank lens, the total thickness of the blank lens needs to be controlled to be 0.2~0.5mm larger than the total thickness of the finished lens, and the step height of the blank lens needs to be 0.2~0.5mm larger than the step height of the finished lens. These two values ​​should be equal. Based on these two conditions, the radius of curvature of the convex surface of the blank lens can be controlled, and the blank lens drawing can be drawn in CAD drawing software. The blank lens can then be manufactured from the blank drawing. This embodiment includes the following steps: (1) First round of rough grinding and adjustment: For rough grinding, due to the large depth of cut, a bronze grinding wheel is selected. In terms of appearance, a grinding wheel with a relatively flat bottom and a small arc angle is chosen. Specifically: the grit size of the grinding wheel is 200 mesh to 100 mesh; the parallelism of the bottom of the grinding wheel is less than 0.01 mm; and the radius of the rounded corner of the grinding wheel is less than 0.5 mm.

[0033] Rough grinding methods such as Figure 4 As shown, the grinding wheel deflects at a certain angle and rotates around its axis of rotation. At position 1, the grinding wheel will first travel a safe distance, and then cut vertically downwards at a speed of 0.05~0.1mm / min. After the vertical cutting is completed, it will start from position 1, pass through position 2, and finally reach position 3 to cut out the platform in a clockwise direction.

[0034] Grinding wheel deflection angle selection: During the first round of rough grinding and adjustment, the light transmission diameter D1 of the cut lens is selected to be approximately half the light transmission diameter of the finished lens, and the curvature of the finished lens is R. The angle between the line connecting the center of the lens to the cutting point of the grinding wheel and the center of rotation of the grinding wheel is α. From the given conditions, α can be calculated as: .

[0035] Choose appropriate helix pitch and helix speed: the helix pitch is 0.01~0.03mm during rough grinding, and the selection of helix speed needs to ensure that the rotation speed of the lens is less than 1000 revolutions per minute when cutting the center part of the lens (too fast a rotation speed makes it difficult to control the surface shape), and satisfy the following relationship between the lens radius and the lens rotation speed.

[0036] During the cutting process in this embodiment, the lens rotation speed is the highest when the grinding wheel cuts the middle part of the lens. Within the lens radius range of 0 to n1%, the lens rotation speed drops to 60% to 40% of the rotation speed of the middle part; within the lens radius range of n1% to n2%, the lens rotation speed drops to 40% to 10%, 10≤n1≤20, 10≤n2≤100.

[0037] Formal cutting: When cutting, first raise the grinding wheel and make the first cut. If the first cut does not reach the center of the blank lens, continue cutting until the center of the blank lens is reached. Then measure the center thickness of the lens and correct and match the theoretical center thickness of the machine tool with the actual center thickness.

[0038] (2) Second round of rough grinding and adjustment: The processing method is the same as the first round of rough grinding and adjustment, except that the planned light transmission diameter to be cut in the second round of rough grinding and adjustment is changed to 94%~97% of the finished lens light transmission diameter D2, such as... Figure 5 As shown, the reason for this adjustment is to make the lens after the second round of rough grinding as close as possible to the finished lens, thus shortening the adjustment time. The center thickness of the second round of rough grinding is controlled to be 0.1~0.15mm larger than the center thickness of the finished lens.

[0039] Measure the distance from the highest point of the convex surface to the step, i.e., the sag of the convex surface. Calculate the actual light-transmitting aperture D3 based on the actual measured sag data. .

[0040] By comparing the size difference between D3 and the finished lens aperture D, the planned aperture was changed to D2+D-D3, which is the method of rough grinding and adjustment.

[0041] (3) After the debugging is completed, perform a trial cut, continue to measure the convex surface height, calculate the actual light transmission aperture, and compare it with the light transmission aperture of the finished lens. If the sizes are the same, the debugging is complete, and the debugged rough grinding program is saved; if they are different, continue the above steps for debugging.

[0042] The preferred rough grinding procedure is as follows: the grinding wheel deflects at an angle α, moves to directly above the lens, descends to a safe distance, and after traveling the safe distance, cuts the center of the lens at a speed of 0.05~0.1mm / min. When the cutting reaches a position 0.05~0.1mm higher than the thickness of the finished lens center, the grinding wheel cuts out the convex curvature and convex sagitta of the lens in a spiral pattern.

[0043] During the milling process, the parameters that need to be adjusted in the rough grinding program include, but are not limited to: Lens: Total lens thickness, convexity sagitta, convexity curvature, and center-crossing of the grinding wheel; Grinding wheel: radius of arc of grinding wheel, height of grinding wheel, pitch diameter of grinding wheel, cutting direction of grinding wheel.

[0044] The parameters obtained after rough grinding and adjustment are the radius of curvature of the grinding wheel, the height of the grinding wheel, the mean diameter of the grinding wheel, and the cutting direction of the grinding wheel. Determining the accurate values ​​of these parameters allows for rough grinding through the rough grinding program, enabling precise control of the total thickness, convexity sagitta, and convexity curvature of the lens.

[0045] (4) Fine grinding and adjustment: For fine grinding, a smaller depth of cut is used, and a bronze grinding wheel is selected. In terms of appearance, a grinding wheel with a relatively flat bottom and a small arc angle is chosen. Specifically: the grinding wheel grit size is 800 mesh to 400 mesh; the parallelism of the grinding wheel bottom is less than 0.01 mm; and the radius of the grinding wheel's corners is less than 0.5 mm.

[0046] Fine grinding methods such as Figure 6 As shown, the grinding wheel deflects at a certain angle and rotates around its axis of rotation. At position 3, it first moves vertically downwards to complete the safety distance, and then cuts to the left or right at a speed of 0.03~0.05 mm / min, and then cuts downwards at a speed of 0.03~0.05 mm / min. After the platform is cut, it passes through position 2 in a spiral shape and finally reaches position 1, where it is machined by rotating counterclockwise to form the entire convex step piece.

[0047] During finish grinding, the helix pitch is used to be 0.04~0.06mm. The reason for a smaller helix pitch during rough grinding is the larger depth of cut. A larger helix pitch results in a faster cutting speed, causing the grinding wheel to reach position 3 more quickly, which can lead to chipping and scrapping of the platform. During finish grinding, because counter-clockwise machining is used, a larger helix pitch is acceptable without affecting the platform's machining and can also reduce machining time. Furthermore, clockwise machining is used during rough grinding because the cutting force at the bottom edge of the grinding wheel is large, allowing for extensive cutting. If this method were used during finish grinding, the platform would experience a large impact force, leading to chipping. Counter-clockwise machining uses the cutting force of the tool sidewall, which is smaller and cannot perform extensive cutting, potentially damaging the tool.

[0048] During the formal fine grinding and adjustment, the planned light transmission diameter to be cut is changed to 97%~99% of the finished lens's light transmission diameter D4. The reason for this adjustment is to make the adjusted lens as close as possible to the finished lens, thus shortening the adjustment time. After fine grinding and adjustment, the center thickness is controlled to be 0.05~0.1mm larger than the finished center thickness.

[0049] Measure the center thickness of the lens, compare it with the data in the program, and then make corrections; Measure the distance from the highest point of the convex surface to the step, i.e., the sag of the convex surface. Calculate the actual light transmission aperture D5 based on the actual measured sag data. .

[0050] By comparing the size difference between D5 and the finished lens aperture D, the planned aperture was changed to D4+D-D5, which is the method of fine grinding and adjustment.

[0051] (5) After the debugging is completed, perform a trial cut, continue to measure the convex surface height, calculate the actual light transmission aperture, and compare it with the light transmission aperture of the finished lens. If the sizes are the same, the debugging is complete, and the fine grinding program that has been debugged is saved; if they are different, continue the above steps for debugging.

[0052] The fine grinding procedure is as follows: the grinding wheel is moved horizontally to a safe distance position of the lens step. After moving to the safe distance, it first cuts to the left or right at 0.03~0.05mm / min, and then cuts downward at 0.03~0.05mm / min. After the platform is cut, it passes through position 2 in a spiral shape and finally reaches position 1. The entire convex step piece is machined by rotating counterclockwise. The total thickness, convex sagitta, and convex curvature of the lens after machining must meet the requirements of the drawing.

[0053] It should be noted that the parameters that need to be adjusted in the finishing grinding program during the milling process include, but are not limited to: Lens: Total lens thickness, convexity sagitta, convexity curvature, and center-crossing of the grinding wheel; Grinding wheel: radius of arc of grinding wheel, height of grinding wheel, pitch diameter of grinding wheel, cutting direction of grinding wheel.

[0054] (6) Formal processing: Rough grinding: Run the pre-tuned rough grinding program, inputting a lens center thickness that is 0.05~0.1mm larger than the finished product center thickness, and begin processing; Fine grinding: Run the pre-tuned fine grinding program, input the lens center thickness to be equal to the finished product center thickness, and begin processing. The result is the finished lens. Figure 7 As shown.

[0055] After debugging, the processing time for a single piece in batch production in this embodiment does not exceed 10 minutes.

[0056] Example 2 This embodiment provides a milling method for a convex stepped lens, involving a blank lens such as... Figure 3As shown, the blank lens needs to be made spherical. When making the blank lens, the total thickness of the blank lens needs to be controlled to be 0.2~0.5mm larger than the total thickness of the finished lens, and the step height of the blank lens needs to be 0.2~0.5mm larger than the step height of the finished lens. These two values ​​should be equal. Based on these two conditions, the radius of curvature of the convex surface of the blank lens can be controlled, and the blank lens drawing can be drawn in CAD drawing software. The blank lens can then be manufactured from the blank drawing. Specifically: the diameter of the finished lens is 35.1mm, the curvature of the finished lens is 43.5, and the light transmission diameter of the finished lens is 27.715mm.

[0057] This embodiment includes the following steps: (1) First round of rough grinding and adjustment: During rough grinding, due to the large depth of cut, a 200-grit bronze grinding wheel with a larger grit is selected. The parallelism of the bottom of the grinding wheel is less than 0.01mm, and the radius of the corner of the grinding wheel is less than 0.5mm. Rough grinding methods such as Figure 4 As shown, the grinding wheel deflects at a certain angle and rotates around its axis of rotation. At position 1, the grinding wheel will first travel a safe distance, and then cut vertically downwards at a speed of 0.05 mm / min. After the vertical cutting is completed, it will start from position 1, pass through position 2, and finally reach position 3 to cut out the platform in a clockwise direction.

[0058] Grinding wheel deflection angle selection: During the first round of rough grinding and adjustment, the light transmission diameter D1 of the cut lens is 12.47mm, and the curvature of the finished lens is 43.5mm. The angle between the line connecting the center of the lens to the cutting point of the grinding wheel and the center of rotation of the grinding wheel is α. From the given conditions, α = 10.46° can be calculated.

[0059] Choose appropriate helix pitch and helix speed: the helix pitch is 0.02mm during rough grinding, and the helix speed should be selected to ensure that the rotational speed of the lens is less than 1000RPM when cutting the center part of the lens, specifically 630RPM, and satisfy the following relationship between the lens radius and the lens rotational speed.

[0060] During the cutting process in this embodiment, the lens rotation speed is at its maximum when the grinding wheel cuts the middle part of the lens. Within a lens radius of 2.08mm, the lens rotation speed rapidly decreases to 253RPM, with a decrease rate of 181.25RPM per millimeter of radius. Within a lens radius range of 2.08mm to 17.55mm, the lens rotation speed slowly decreases to 70RPM, with a decrease rate of 15.54RPM per millimeter of radius.

[0061] Formal cutting: When cutting, first raise the grinding wheel and make the first cut. If the first cut does not reach the center of the blank lens, continue cutting until the center of the blank lens is reached. Then measure the center thickness of the lens and correct and match the theoretical center thickness of the machine tool with the actual center thickness.

[0062] (2) Second round of rough grinding and adjustment: The processing method is the same as the first round of rough grinding and debugging, except that the planned aperture diameter to be cut is changed to 26.33mm during the second round of rough grinding and debugging. Figure 5 As shown, the reason for this adjustment is to make the lens after the second round of rough grinding as close as possible to the finished lens, thus shortening the adjustment time. The center thickness of the second round of rough grinding is controlled to be 0.12mm larger than the center thickness of the finished lens.

[0063] Measure the distance from the highest point of the convex surface to the step, i.e., the convex surface sag. Based on the actual measured convex surface sag (sag) data, calculate the actual light transmission aperture D3 = 27.7mm.

[0064] By comparing the size difference between D3 and the finished lens aperture D, the planned aperture was changed to D2+D-D3, which is the method of rough grinding and adjustment.

[0065] (3) After debugging, perform a trial cut, continue to measure the convex surface height, calculate the actual light transmission diameter, and compare it with the light transmission diameter of the finished lens. If the sizes are the same, the debugging is complete; if they are different, continue the above steps for debugging. In this embodiment, step (2) is repeated once for debugging. After debugging, the actual light transmission diameter is the same as the calculated light transmission diameter.

[0066] (4) Fine grinding and adjustment: After fine grinding, the surface roughness Rq of the lens must be less than or equal to 0.5μm. During fine grinding, the depth of cut is small, and a 400-grit bronze grinding wheel with a fine grit is selected. For appearance, a grinding wheel with a flat bottom and a small radius of curvature is chosen. Fine grinding methods such as Figure 6 As shown, the grinding wheel deflects at a certain angle and rotates around its axis of rotation. At position 3, it first moves vertically downwards to complete the safety distance, and then cuts to the left at 0.05 mm / min, and then cuts downwards at 0.05 mm / min. After the platform is cut, it passes through position 2 in a spiral shape and finally reaches position 1. The entire convex step piece is machined by rotating counterclockwise.

[0067] The helix pitch during finish grinding is 0.04mm. The smaller helix pitch during rough grinding is due to the larger depth of cut. A larger helix pitch results in a faster cutting speed, causing the grinding wheel to reach position 3 more quickly, which can lead to chipping and scrapping of the platform. During finish grinding, a counter-clockwise machining direction allows for a larger helix pitch without affecting the platform's machining and can also reduce machining time. Furthermore, the clockwise direction is used during rough grinding because the cutting force at the bottom edge of the grinding wheel is large, allowing for extensive cutting. If this method were used during finish grinding, the platform would experience a large impact force, leading to chipping. Counter-clockwise machining uses the cutting force of the tool sidewall, which is smaller and cannot perform extensive cutting, potentially damaging the tool.

[0068] During the formal fine grinding and debugging, the planned aperture diameter to be cut was changed to 26.88mm, such as... Figure 6 As shown, the reason for this adjustment is to make the adjusted lens as close as possible to the finished lens, thus shortening the adjustment time. After fine grinding and adjustment, the center thickness is controlled to be 0.05mm larger than the center thickness of the finished product.

[0069] Measure the center thickness of the lens, compare it with the data in the program, and then make corrections; Measure the distance from the highest point of the convex surface to the step, i.e., the convex surface sag. Based on the actual measured convex surface sag (sag) data, calculate the actual light transmission aperture D5 = 27.13mm.

[0070] By comparing the size difference between D5 and the finished lens aperture D, the planned aperture was changed to D4+D-D5, which is the method of fine grinding and adjustment.

[0071] (5) After the debugging is completed, perform a trial cut, continue to measure the convex surface height, calculate the actual light transmission aperture, and compare it with the light transmission aperture of the finished lens. If the sizes are the same, the debugging is complete; if they are different, continue the above steps for debugging.

[0072] In step (5) of this embodiment, step (4) is repeated once for debugging. After debugging, the actual light transmission aperture is the same as the calculated light transmission aperture.

[0073] (6) Formal processing: Rough grinding: Run the pre-tuned rough grinding program, inputting a lens center thickness that is 0.08mm larger than the finished product center thickness, and begin processing; Fine grinding: Run the pre-tuned fine grinding program, input the lens center thickness to be equal to the finished product center thickness, and begin processing. The result is the finished lens. Figure 7 As shown.

[0074] After debugging, the single-piece processing time for mass production in this embodiment is 7 minutes.

[0075] Comparative Example 1 For example Figure 3 The blank lenses shown are currently being produced using methods such as... Figure 1 The milling process for the convex stepped sheet shown in the figure involves a grinding wheel rotating around a pivot axis while remaining vertical. The edge of the grinding wheel is used to cut the convex stepped sheet, while the blank lens rotates around its pivot axis. The grinding wheel moves clockwise from point A to point E relative to the blank lens in a spiral motion, and the convex and stepped surfaces are cut precisely at point E.

[0076] like Figure 2 As shown in Comparative Example 1, during the milling process, the grinding wheel does not deflect at an angle, and it is impossible for the grinding wheel to maintain a good arc angle. Therefore, the same grinding wheel edge point is not used when cutting each spiral of the lens. This results in a poor convex surface profile after machining and produces obvious cutting marks.

[0077] Comparative Example 2 This comparative example is basically the same as Example 2, except that: During rough grinding and adjustment, the relationship between the lens rotation speed and the lens radius is as follows: When the grinding wheel cuts the middle part of the lens, the lens rotation speed is the largest. Within the lens radius of 2.08mm, the lens rotation speed remains constant. Within the lens radius range of 2.08mm to 17.55mm, the lens rotation speed uniformly decreases to 70RPM.

[0078] The surface shape of the processed lens obtained in this comparative example is not up to standard.

[0079] Comparative Example 3 This comparative example is basically the same as Example 2, except that: During both the debugging and formal processing, the grinding process is carried out from the center outwards during fine grinding.

[0080] This comparison model indicates that edge chipping may occur at the lens step during fine grinding.

[0081] Comparative Example 4 This comparative example is basically the same as Example 2, except that: During the debugging and formal processing, the method used during fine grinding is adopted during rough grinding.

[0082] The cutting amount in this comparative example was too large, which led to the damage of the rough grinding wheel.

[0083] Comparative Example 5 This comparative example is basically the same as Example 2, except that: The thread pitch increases during the fine and rough grinding processes in this comparative example.

[0084] The increased cutting speed in this comparative example caused edge chipping on the lens platform.

[0085] Comparative Example 6 This comparative example is basically the same as Example 2, except that: In this comparative example, the thread size decreased by 0.01 mm in both the fine and rough grinding processes.

[0086] After the comparative debugging was completed, the processing time for a single piece in mass production increased and the efficiency decreased.

[0087] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A milling method for a stepped convex surface of a lens, characterized in that, Includes the following steps: (1) Coarse grinding and adjustment: The grinding wheel rotates around its axis of rotation to perform rough grinding on the lens. The rough grinding starts at the top of the lens and is performed vertically at the starting point. After the vertical cutting is completed, a platform is formed by cutting from the starting point in a spiral pattern. During the cutting process, the angle between the line connecting the center of the lens to the cutting point of the grinding wheel and the center of rotation of the grinding wheel is α. R is the curvature of the finished lens, and the cut aperture D2 is 94%~97% of the finished lens aperture D; After rough grinding and adjustment, measure the distance from the highest point of the convex surface of the lens to the step, set it as the convex surface sag, and calculate the actual light transmission aperture D3. The calculated optical aperture is D2+D-D3; (2) If the planned light transmission diameter D2+D-D3 = the finished lens light transmission diameter D, then the rough grinding and adjustment is completed; if the planned light transmission diameter D2+D-D3 ≠ the finished lens light transmission diameter D, then repeat step (1) until the planned light transmission diameter D2+D-D3 = the finished lens light transmission diameter D. After the rough grinding test is completed, save the tested rough grinding program and proceed with the fine grinding test. (3) Fine grinding and adjustment: Maintaining a cutting angle of α, the grinding wheel rotates around its axis to finely grind the lens. The fine grinding begins at the step, with vertical cutting performed first. After the vertical cutting is completed, a spiral cut is made from the starting point to the top of the lens to form a convex stepped piece. The light transmission diameter D4 of the cut is 97% to 99% of the light transmission diameter D of the finished lens. After fine grinding and adjustment, the distance from the highest point of the convex surface to the step is measured as the convex surface sag, and the actual light transmission diameter D5 is calculated. The calculated optical aperture is D4+D-D5; (4) If the planned light transmission diameter D4+D-D5 = the finished lens light transmission diameter D, then the fine grinding and adjustment is completed; if the planned light transmission diameter D4+D-D5 ≠ the finished lens light transmission diameter D, then repeat step (3) until the planned light transmission diameter D4+D-D5 = the finished lens light transmission diameter D. After the fine grinding and debugging are completed, save the debugged fine grinding program and proceed with the formal processing; (5) Formal processing: Run the debugged rough grinding program to begin processing; After the rough grinding program is completed, run the fine grinding program that has been debugged, input the center thickness of the lens to be equal to the center thickness of the finished product, and start processing to obtain the finished lens.

2. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that, In step (1), the grinding wheel is a bronze grinding wheel.

3. The milling method for the convex stepped surface of a lens as described in claim 1 or 2, characterized in that, In step (1), the grit size of the grinding wheel is 200 mesh to 100 mesh.

4. The milling method for the convex stepped surface of a lens as described in claim 1 or 2, characterized in that, In step (1), the parallelism of the bottom of the grinding wheel is less than 0.01 mm.

5. The milling method for the convex stepped surface of a lens as described in claim 1 or 2, characterized in that, In step (1), the radius of the fillet of the grinding wheel is less than 0.5 mm.

6. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that, In step (1), the helical pitch is 0.01~0.03mm, and the selection of the helical linear velocity needs to ensure that the rotational speed of the lens is less than 1000rpm when cutting the center part of the lens.

7. The milling method for the convex stepped surface of a lens as described in claim 6, characterized in that, In step (1), when the grinding wheel cuts the middle part of the lens, the lens rotation speed is the maximum. Within the lens radius range of 0~n1%, the lens rotation speed drops to 60%~40% of the rotation speed of the middle part; within the lens radius range of n1%~n2%, the lens rotation speed drops to 40%~10%, 10≤n1≤20, 10≤n2≤100.

8. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that, In step (1), the grinding wheel is raised first during cutting, and the first cut is made. If the first cut does not reach the center of the blank lens, the next cut is made until the center of the blank lens is reached. Then the center thickness of the lens is measured, and the theoretical center thickness of the machine tool is corrected and matched with the actual center thickness. The correction matching specifically involves comparing the actual measured center thickness of the lens with the theoretical center thickness of the lens, calculating the difference, and then using this difference to compensate for the tool dimensions of the machine tool.

9. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that, In step (1), the starting point position is first cut vertically downwards at a speed of 0.05~0.1mm / min.

10. The milling method for a convex stepped lens surface as described in any one of claims 1 to 9, characterized in that, Step (1) Before rough grinding and adjustment, perform pre-rough grinding and adjustment: The grinding wheel rotates around its axis to perform rough grinding on the lens. The rough grinding starts at the top of the lens and is performed vertically at the starting point. After the vertical cutting is completed, a platform is formed by cutting from the starting point in a spiral pattern. During the cutting process, the angle between the line connecting the center of the lens to the cutting point of the grinding wheel and the center of rotation of the grinding wheel is α. R is the curvature of the finished lens, and the light transmission diameter D1 is 40% to 60% of the light transmission diameter D of the finished lens.

11. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that, In step (3), the grinding wheel is a bronze grinding wheel.

12. The milling method for the convex stepped surface of a lens as described in claim 1 or 11, characterized in that, In step (3), the grit size of the grinding wheel is 800 mesh to 400 mesh.

13. The milling method for the convex stepped surface of a lens as described in claim 1 or 11, characterized in that, In step (3), the parallelism of the bottom of the grinding wheel is less than 0.01 mm.

14. The milling method for the convex stepped surface of a lens as described in claim 1 or 11, characterized in that, In step (3), the radius of the fillet of the grinding wheel is less than 0.5 mm.

15. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that, In step (3), during fine grinding and adjustment, first move vertically downwards to complete the safety distance at the starting point of fine grinding, then first move to the left or right at 0.03~0.05mm / min to cut, and then move downwards at 0.03~0.05mm / min to cut the platform. After the platform is cut, cut to the top of the lens in a spiral shape to process the entire convex step sheet.

16. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that, In step (3), the pitch of the spiral is 0.04~0.06mm; the surface roughness of the lens after fine grinding is less than or equal to 0.5μm.

17. The milling method for the convex stepped surface of a lens as described in claim 1, characterized in that: In step (2), the center thickness of the lens after rough grinding and adjustment is controlled to be 0.1~0.15mm larger than the center thickness of the finished lens; In step (4), after fine grinding and adjustment, the center thickness is controlled to be 0.05~0.1mm larger than the center thickness of the finished product; In step (5), run the adjusted rough grinding program and input the lens center thickness 0.05~0.1mm larger than the finished product center thickness.

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