Numerical control method for fine grinding of aspheric cup-shaped grinding wheel

Abstract

The application belongs to the field of optical processing, and discloses a numerical control aspheric cup-shaped grinding wheel fine grinding method, which comprises the following steps: (1) preparing incoming lens, one side of the incoming lens is a spherical surface, and the other side is provided with a platform; the spherical surface is the best fitting spherical surface of the target aspheric surface; (2) edge thickness deviation measurement; (3) bonding and table making; (4) using the cup-shaped grinding wheel to perform aspheric fine grinding; (5) detecting the surface type precision PV99 of the incoming lens after fine grinding, if the target surface type precision is reached, the process is ended, if the target surface type precision is not reached, the detection result is introduced into the numerical control machine tool correction item to perform surface type correction; (6) repeating steps (4)-(5) until the target surface type precision is reached. The application is suitable for aspheric fine grinding, has high processing efficiency, short processing time, shallow damage layer on the aspheric lens surface, saves polishing time for subsequent aspheric polishing, and is beneficial to the control of the polishing surface type.

Description

Technical Field

[0001] This invention belongs to the field of optical processing, specifically relating to a CNC method for precision grinding of aspherical cup-shaped grinding wheels. Background Technology

[0002] With the increasing demand for aspherical lenses with apertures of 150-400mm, long focal lengths, and wide viewing angles in fields such as aerospace and space exploration, the original spherical processing technology is vastly different from aspherical processing technology in terms of technical principles.

[0003] For the roughing of spherical lenses, the current mainstream processing methods are spherical milling and CNC lathe turning. For aspherical lenses, the current roughing method can only be point contact processing along the aspherical surface curve. This has the following problems: (1) It puts a lot of pressure on the lens surface, which can easily damage the machine tool spindle, destroy the layer depth, and is not conducive to subsequent polishing; (2) It is generally a point contact method with a small ball grinding head. For aspherical surfaces, due to the small diameter of the grinding head, the cutting speed is low, the cutting efficiency is low, and the surface roughness is large; (3) The processing time is long, requiring eight or nine hours to process one side. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a CNC method for precision grinding of aspherical cup-shaped grinding wheels. This method has high processing efficiency, short processing time, and shallow destructive layer on the surface of aspherical lenses, saving polishing time for subsequent aspherical polishing, while also facilitating control of the polished surface shape.

[0005] To achieve the objectives of this invention, the specific technical solution is as follows:

[0006] A method for precision grinding of aspherical cup-shaped grinding wheels by CNC includes the following steps:

[0007] (1) Prepare incoming lenses, one side of which is spherical and the other side is provided with a platform; the spherical surface is the best-fit spherical surface of the target aspherical surface, and the target aspherical surface refers to the aspherical surface that is to be achieved after fine grinding with a cup-shaped grinding wheel;

[0008] (2) Edge thickness deviation measurement: Perform ETV measurement on the spherical surface of the incoming lens on a thickness gauge, and mark the positions of the lowest point, the highest point and at least one intermediate value;

[0009] (3) Adhesive bonding and dial indicator printing: Use adhesive to bond the platform side of the material lens to the flat end of the tooling chuck. The chuck end of the tooling chuck is fixed on the CNC machine tool. The dial indicator is printed to print the value measured in step (2) to the corresponding position.

[0010] (4) The aspherical surface fine grinding process is carried out using a cup-shaped grinding wheel. The parameters are set as follows: input the height of the tooling chuck and the thickness of the center of the incoming lens in the CNC machine tool, and use a fixed thread pitch P and a fixed cutting speed V for fine grinding. The thread pitch P is 0.03~0.1mm, the cutting speed V is 8000~15000mm / min, and the rotation speed of the cup-shaped grinding wheel is 5000~7000r / min.

[0011] When the cup-shaped grinding wheel performs aspherical surface fine grinding, its processing point moves from the end of the incoming lens to the center of the incoming lens. As the processing point moves from the outer end of the incoming lens to the center of the incoming lens, the rotation speed of the incoming lens gradually increases from 0.2~0.8 r / min to 200~400 r / min. The rotation direction of the cup-shaped grinding wheel is opposite to that of the incoming lens.

[0012] (5) Check the surface profile accuracy PV99 of the lens after fine grinding. If the target surface profile accuracy is achieved, the process ends; if the target surface profile accuracy is not achieved, import the test results into the CNC machine tool correction project for surface profile correction.

[0013] (6) Repeat steps (4) to (5) until the target surface accuracy is achieved.

[0014] Further, in step (1), the positions of the lowest point, the highest point, and the two intermediate values ​​are marked.

[0015] Furthermore, in step (3), the error is controlled within 1 to 4 micrometers during the dialing process.

[0016] Furthermore, in step (3), the adhesive is at least one of rosin, paraffin wax, asphalt, and quick-drying 502 glue.

[0017] More preferably, the bonding process involves: applying adhesive to the flat end of the tooling clamp, placing the tooling clamp on a heating table or under a heating lamp to bake until the adhesive is completely melted into a liquid state, and then placing the side of the incoming lens platform with the platform on the tooling clamp and letting it stand for 1 to 3 minutes until the lens no longer slips.

[0018] More preferably, in step (4), the cup-shaped grinding wheel starts to feed from the outer end of the incoming lens. During the feeding process, the depth of cut is controlled to be 0.005~0.05mm and the feed speed is 0.5~1mm / min.

[0019] Furthermore, in step (4), during the aspherical fine grinding process, when the cup-shaped grinding wheel performs aspherical fine grinding, its processing point has a left cutting edge and a right cutting edge. When the left cutting edge is processed, it moves from the left end of the incoming lens to the middle position of the incoming lens according to the aspherical surface shape; the right cutting edge moves from the right end of the incoming lens to the middle position of the incoming lens according to the aspherical surface shape.

[0020] Furthermore, in step (5), the target surface accuracy PV99 is 0.4~1.5 micrometers.

[0021] Furthermore, step (5) also includes, if the target surface accuracy is not achieved, performing contour detection on the incoming lens and importing the contour detection data into the CNC machine tool for surface correction.

[0022] Furthermore, let n be the distance from the processing point to the center of the incoming lens. Rotation speed of incoming lenses during processing R is the maximum radius of the incoming lens, A is the maximum rotational speed of the incoming lens, [X] indicates that the processing point is located on the [X]th spiral on the incoming lens, 0≤[X]≤R / P, and [X] is an integer value.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The CNC aspherical cup-shaped grinding wheel fine grinding method of the present invention is suitable for aspherical fine grinding, with high processing efficiency, short processing time, shallow damage layer on the surface of aspherical lens, saving polishing time for subsequent aspherical polishing, and also facilitating the control of polishing surface shape.

[0025] (2) The single processing time of the CNC aspherical cup-shaped grinding wheel precision grinding method of the present invention can be reduced to 1.5h; the eccentricity of the lens after processing is less than 0.001mm. Attached Figure Description

[0026] 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:

[0027] Figure 1 This is a diagram showing the results of edge thickness deviation measurement in step (2) of Example 1.

[0028] Figure 2 This is a schematic diagram of the cup-shaped grinding wheel machining point and machining direction in step (4) of Example 1.

[0029] Figure 3 This is a schematic diagram of the aspherical grinding parameters P and V in step (4) of Examples 1 and 2.

[0030] Figure 4 The image shows the contour detection result in step (5) of Example 1.

[0031] Figure 5 This is a diagram showing the results of edge thickness deviation measurement in step (2) of Example 2.

[0032] Figure 6This is a schematic diagram of the cup-shaped grinding wheel machining point and machining direction in step (4) of Example 2.

[0033] Figure 7 The image shows the contour detection result in step (5) of Example 2. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Example 1

[0038] See Figures 1-4 As shown in the figure, this embodiment discloses a CNC aspherical cup-shaped grinding wheel precision grinding method, including the following steps:

[0039] (1) Prepare incoming lens material, one side of the incoming spherical surface is a convex spherical surface and the other side is a concave surface, and a platform is provided at the end of the concave surface; the convex spherical surface is the best fitting spherical surface of the target aspherical surface after fine grinding in this embodiment;

[0040] (2) Edge thickness deviation measurement: Perform ETV measurement on the convex spherical surface of the incoming lens using a thickness gauge, and mark the positions of the lowest point, the highest point, and two intermediate values, as follows: Figure 1 As shown;

[0041] (3) Bonding and dialing: Spread rosin on the flat end of the tooling chuck, place the tooling chuck under a heating table or heating lamp and bake until the rosin is completely melted into liquid. Then place the side of the incoming lens platform with the platform on the tooling chuck and let it stand for 1~3 minutes until the lens does not slide. Fix the chuck end of the tooling chuck on the CNC machine tool and perform dialing. Mark the value measured in step (2) to the corresponding position and control the error within 1~4 micrometers.

[0042] (4) such as Figure 2 and 3As shown, a cup-shaped grinding wheel is used for the aspherical surface fine grinding process. The parameters are set as follows: the height of the tooling chuck and the thickness of the center of the incoming lens are input into the CNC machine tool. The fine grinding is performed using a fixed thread pitch P and a fixed cutting speed V. The thread pitch P is 0.03 mm, the cutting speed V is 10000 mm / min, and the rotation speed of the cup-shaped grinding wheel around O1O2 is 6650 r / min.

[0043] When the cup-shaped grinding wheel performs aspherical fine grinding, its processing point moves from the end A of the incoming material lens to the center B of the incoming material lens. As the processing point moves from the outer end of the incoming material lens to the center of the incoming material lens, the rotation speed n of the incoming material lens around O3O4 gradually increases from 0.5 r / min to 200 r / min. The rotation direction of the cup-shaped grinding wheel is opposite to that of the incoming material lens.

[0044] Specifically, as one of the preferred solutions in this embodiment: R is the maximum radius of the incoming lens (85mm in this embodiment), and n is the distance from the processing point to the center of the incoming lens. The rotational speed of the incoming lens is A, which is the maximum rotational speed of the incoming lens (200 r / min in this embodiment). [X] indicates that the processing point is located on the [X]th spiral on the incoming lens, and 0 ≤ [X] ≤ R / P.

[0045] During the infeed process of the cup-shaped grinding wheel, the depth of cut is controlled at 0.03 mm and the feed rate is 0.5 mm / min;

[0046] In this embodiment, during the aspherical surface fine grinding process, when the cup-shaped grinding wheel performs aspherical surface fine grinding, its processing point is the right cutting edge. The right cutting edge moves from the right end of the incoming lens to the middle position of the incoming lens according to the aspherical surface shape.

[0047] (5) The surface profile accuracy PV99 of the incoming lens after fine grinding is 2.098 micrometers. The surface profile accuracy PV99 that does not meet the target is 0.4~1.5 micrometers. The contour of the incoming lens is then inspected, and the inspection results are as follows: Figure 4 As shown, the contour detection data is imported into the CNC machine tool for surface correction;

[0048] (6) Repeat steps (4) to (5) once more in this embodiment to achieve a target surface accuracy of PV99 of 0.4 to 1.5 micrometers.

[0049] According to the records, this embodiment took 60 minutes.

[0050] Example 2

[0051] See Figures 4-7 As shown in the figure, this embodiment discloses a CNC aspherical cup-shaped grinding wheel precision grinding method, including the following steps:

[0052] (1) Prepare incoming lens material, one side of the incoming spherical surface is a convex spherical surface and the other side is a concave surface, and a platform is provided at the end of the concave surface; the convex spherical surface is the best-fit spherical surface of the target aspherical surface in this embodiment;

[0053] (2) Edge thickness deviation measurement: Perform ETV measurement on the convex spherical surface of the incoming lens using a thickness gauge, and mark the positions of the lowest point, the highest point, and two intermediate values, as follows: Figure 5 As shown;

[0054] (3) Bonding and dialing: Spread rosin on the flat end of the tooling chuck, place the tooling chuck under a heating table or heating lamp and bake until the rosin is completely melted into liquid. Then place the side of the incoming lens platform with the platform on the tooling chuck and let it stand for 1~3 minutes until the lens does not slide. Fix the chuck end of the tooling chuck on the CNC machine tool and perform dialing. Mark the value measured in step (2) to the corresponding position and control the error within 1~4 micrometers.

[0055] (4) such as Figure 6 and 3 As shown, a cup-shaped grinding wheel is used for the aspherical surface fine grinding process. The parameters are set as follows: the height of the tooling chuck and the thickness of the center of the incoming lens are input into the CNC machine tool. The fine grinding is performed using a fixed thread pitch P and a fixed cutting speed V. The thread pitch P is 0.1 mm, the cutting speed V is 10000 mm / min, and the rotation speed of the cup-shaped grinding wheel around O1O2 is 6650 r / min.

[0056] When the cup-shaped grinding wheel performs aspherical fine grinding, its processing point moves from the end of the incoming lens to the center of the incoming lens. As the processing point moves from the outer end of the incoming lens to the center of the incoming lens, the rotation speed n of the incoming lens around O3O4 gradually increases from 0.5 r / min to 200 r / min. The rotation direction of the cup-shaped grinding wheel is opposite to that of the incoming lens.

[0057] Specifically, as one of the preferred solutions in this embodiment: R is the maximum radius of the incoming lens (102mm in this embodiment), and n is the distance from the processing point to the center of the incoming lens. The rotational speed of the incoming lens is A, which is the maximum rotational speed of the incoming lens (200 r / min in this embodiment). [X] indicates that the processing point is located on the [X]th spiral on the incoming lens, and 0 ≤ [X] ≤ R / P.

[0058] During the infeed process of the cup-shaped grinding wheel, the depth of cut is controlled at 0.03 mm and the feed rate is 0.5 mm / min;

[0059] In this embodiment, during the aspherical surface fine grinding process, when the cup-shaped grinding wheel performs aspherical surface fine grinding, its processing point is at the right cutting edge. The right cutting edge moves from the right end of the incoming lens to the middle position of the incoming lens according to the aspherical surface shape.

[0060] (5) The surface profile accuracy PV99 of the incoming lens after fine grinding is 1.515 micrometers. The surface profile accuracy PV99 that does not meet the target is 0.4~1.5 micrometers. The contour of the incoming lens is then inspected, and the inspection results are as follows: Figure 7 As shown, the contour detection data is imported into the CNC machine tool for correction;

[0061] (6) Repeat steps (4) to (5) once more in this embodiment to achieve a target surface accuracy of PV99 of 0.4 to 1.5 micrometers.

[0062] According to the records, this embodiment took 30 minutes.

[0063] 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 method for precision grinding of a CNC aspherical cup-shaped grinding wheel, characterized in that, Includes the following steps: (1) Prepare incoming lenses, one side of which is spherical and the other side is provided with a platform; the spherical surface is the best-fit spherical surface of the target aspherical surface; (2) Edge thickness deviation measurement: Perform ETV measurement on the spherical surface of the incoming lens on a thickness gauge, and mark the positions of the lowest point, the highest point and at least one intermediate value; (3) Adhesive marking: Use at least one of the following adhesives: rosin, paraffin, asphalt, and quick-drying 502 glue to bond the platform side of the material lens to the flat end of the tooling chuck. The chuck end of the tooling chuck is fixed on the CNC machine tool for marking. During the marking process, the error is controlled within 1~4 micrometers. The value measured in step (2) is marked to the corresponding position. (4) The aspherical surface fine grinding process is carried out using a cup-shaped grinding wheel. The parameters are set as follows: input the height of the tooling chuck and the thickness of the center of the incoming lens in the CNC machine tool, and use a fixed thread pitch P and a fixed cutting speed V for fine grinding. The thread pitch P is 0.03~0.1mm, the cutting speed V is 8000~15000mm / min, and the rotation speed of the cup-shaped grinding wheel is 5000~7000r / min. When the cup-shaped grinding wheel performs aspherical surface fine grinding, its processing point moves from the end of the incoming lens to the center of the incoming lens. As the processing point moves from the outer end of the incoming lens to the center of the incoming lens, the rotation speed of the incoming lens gradually increases from 0.2~0.8 r / min to 200~400 r / min. The rotation direction of the cup-shaped grinding wheel is opposite to that of the incoming lens. (5) Check the surface profile accuracy PV99 of the lens after fine grinding. If the target surface profile accuracy is achieved, the process ends; if the target surface profile accuracy is not achieved, import the test results into the CNC machine tool correction project for surface profile correction. (6) Repeat steps (4) to (5) until the target surface accuracy is achieved.

2. The CNC aspherical cup-shaped grinding wheel precision grinding method as described in claim 1, characterized in that, In step (1), mark the positions of the lowest point, the highest point, and the two intermediate values.

3. The CNC aspherical cup-shaped grinding wheel precision grinding method as described in claim 1, characterized in that, The bonding process is as follows: apply the adhesive to the flat end of the tooling chuck, place the tooling chuck on a heating table or under a heating lamp and bake until the adhesive is completely melted into a liquid state, then place the side of the incoming lens with the platform on the tooling chuck and let it stand for 1 to 3 minutes until the lens no longer slips.

4. The CNC aspherical cup-shaped grinding wheel precision grinding method as described in claim 1, characterized in that, In step (4), the cup-shaped grinding wheel starts to feed from the outer end of the incoming lens. During the feeding process, the depth of cut is controlled to be 0.005~0.05mm and the feed speed is 0.5~1mm / min.

5. The CNC aspherical cup-shaped grinding wheel precision grinding method as described in claim 1, characterized in that, In step (4), during the aspherical fine grinding process, when the cup-shaped grinding wheel performs aspherical fine grinding, its processing point has a left cutting edge and a right cutting edge. When the left cutting edge is processed, it moves from the left end of the incoming lens to the middle position of the incoming lens according to the aspherical surface shape; the right cutting edge moves from the right end of the incoming lens to the middle position of the incoming lens according to the aspherical surface shape.

6. The CNC aspherical cup-shaped grinding wheel precision grinding method as described in claim 1, characterized in that, In step (5), the target surface accuracy PV99 is 0.4~1.5 micrometers.

7. The CNC aspherical cup-shaped grinding wheel precision grinding method as described in claim 1, characterized in that, Step (5) also includes, if the target surface accuracy is not achieved, performing contour detection on the incoming lens and importing the contour detection data into the CNC machine tool for correction.

8. The CNC aspherical cup-shaped grinding wheel precision grinding method according to any one of claims 1 to 7, characterized in that, Let n be the distance from the processing point to the center of the incoming lens. Rotation speed of incoming lenses during processing. R is the maximum radius of the incoming lens, A is the maximum rotational speed of the incoming lens, [X] indicates that the processing point is located on the [X]th spiral on the incoming lens, 0≤ [X]≤ R / P, and [X] is an integer value.

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