A tooling and alignment method for slow tool servo machining of Zernike free-form surfaces

Abstract

The present invention relates to a tooling for slow tool servo machining of a Zernike free-form surface, including a tooling base and a boss. The boss is a cube, and the end face of the boss is a square circumscribing the outer contour of the workpiece. The boss is disposed on the tooling base. The tooling base is a cylinder, and the end face of the tooling base is a circle. The center of the circle coincides with the center of the square. A circular groove corresponding to the mark on the workpiece is provided at the center of one side of the square. By aligning the mark on the workpiece with the circular groove and making the outer contour of the workpiece tangent to each side of the square, the coordinate system of the workpiece and the tooling is made to coincide. By performing centering adjustment on the tooling, adjusting the tooling in the X and Y directions, and adjusting the zero position of the C axis of the machine tool, the coordinate system of the tooling and the machine tool is made to coincide, realizing high-precision and rapid adjustment of centering and X-axis parallelism during the secondary clamping process of the free-form surface optical element.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-precision turning machining, and particularly to a tooling and alignment method for slow tool servo machining of Zernike free-form surfaces. Background Art

[0002] Optical free-form surface elements have unique geometric structures and optical imaging effects, and the application requirements in the fields of aerospace, national defense, precision instruments, etc. are becoming increasingly extensive. However, due to the complex geometric surface shape and high precision requirements of free-form surfaces, their manufacturing is difficult. The slow tool servo machining technology based on single-point diamond turning machines is considered an effective method for machining free-form surfaces. Using this method, optical elements with nano-level surface quality meeting the requirements of optical systems can be machined with high efficiency, high precision, and low cost.

[0003] Currently, it is often difficult to achieve the required precision in slow tool servo machining of free-form surfaces due to the influence of various errors. At the same time, the machining time is relatively long, and there are factors such as insufficient position measurement compensation, requiring repeated clamping. Compared with the installation of traditional rotary optical elements, which only requires determining the center positions of the workpiece and the tool, the machining of free-form surfaces also needs to consider the parallelism between the X-axis of the workpiece and the X-axis of the machine tool. The tooling commonly used in ultra-precision turning machining generally does not consider this problem. The main solution is to mark simultaneously on the machine tool chuck and fixture at the end of the previous turning. In the next round of machining, the worker roughly aligns by visually observing the marks, and multiple turnings are used to remove the alignment errors. Although this method is simple to operate, the removal amount in the first turning is unstable, which is likely to cause tool wear and reduce the machining efficiency. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] The embodiments of the present invention provide a tooling and alignment method for slow tool servo machining of Zernike free-form surfaces, which solves the technical problem that the deviation between the workpiece coordinate system and the machine tool coordinate system during the secondary clamping of free-form surface optical elements in ultra-precision turning machining affects the turning machining efficiency.

[0006] (2) Technical Solutions

[0007] In a first aspect, an embodiment of the present invention provides a tooling for slow tool servo machining of Zernike free-form surfaces, including: a tooling base and a boss. The boss is a cube, and the end face of the boss is a square circumscribing the outer contour of the workpiece. The boss is arranged on the tooling base. The tooling base is a cylinder, and the end face of the tooling base is a circle. The center of the circle coincides with the center of the square. A circular groove corresponding to the mark on the workpiece is opened at the center of one side of the square.

[0008] Further, a plurality of through holes are provided on the convex platform, and the through holes penetrate through the convex platform and the tooling base at the same time.

[0009] Further, the through holes are evenly distributed along the circumferences of circles with different diameters.

[0010] Further, the circular groove is located in the positive Y-axis direction of the convex platform.

[0011] Further, the diameter of the circular groove is 0.5 mm.

[0012] In a second aspect, an alignment method for Zernike free-form slow tool servo machining is provided, including the steps of: setting a mark in the positive Y-axis direction of the workpiece in the rough machining stage; aligning the mark of the workpiece with the circular groove, and making the outer contour of the workpiece tangent to each side of the square, so that the workpiece coincides with the coordinate system of the tooling; starting the spindle vacuum chuck of the machine tool to combine and fix the workpiece on the spindle vacuum chuck; performing centering adjustment on the tooling; performing X and Y direction adjustments on the tooling, measuring and calculating the X-axis horizontal offset angle θ of the tooling on the spindle vacuum chuck; adjusting the zero position of the C-axis of the machine tool according to the angle and direction of θ, so that the tooling coincides with the coordinate system of the machine tool.

[0013] Further, the centering adjustment is specifically to abut the measuring head of the dial indicator against the cylindrical surface of the tooling base, measure the outer circle runout of the cylindrical surface, adjust the position of the tooling so that the runout is controlled within 1 μm, and coincide the Z-axis of the machine tool coordinate system with the Z-axis of the tooling.

[0014] Further, the X and Y direction adjustments are specifically to abut the measuring head of the dial indicator against the side of the convex platform away from the circular groove, horizontally move the X-axis to obtain the display values of points A and B on the convex platform as a and b respectively, and calculate the vertical height H through the display values of points A and B; the calculation formula for the vertical height H is: H = b - a; given that the side length of the convex platform is a known value L, the calculation formula for the X-axis horizontal offset angle θ is:

[0015] (3) Beneficial effects

[0016] In summary, the beneficial effects of the present invention are as follows:

[0017] (1) High positioning accuracy, which can simultaneously meet the requirements of the center deviation and the horizontal direction deviation for the machining of free-form optical elements;

[0018] (2) Simple tooling manufacturing, the overall structure of the tooling is simple, the accuracy of the key datum is guaranteed during the manufacturing process, and the manufacturing cost is low;

[0019] (3) Simple operation, the alignment method is simple and easy to implement, and the requirements for operators are not high. Description of the drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for use in the embodiments of the present invention. Obviously, the following described accompanying drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0021] Figure 1 is a schematic structural diagram of a tooling for slow tool servo machining of a Zernike free-form surface;

[0022] Figure 2 is a front view schematic diagram of a tooling for slow tool servo machining of a Zernike free-form surface;

[0023] Figure 3 is a sectional view schematic diagram of a tooling for slow tool servo machining of a Zernike free-form surface;

[0024] Figure 4 is a schematic diagram of an alignment method for slow tool servo machining of a Zernike free-form surface;

[0025] In the figure: 1, tooling base; 2, boss; 3, circular groove; 4, through hole; 5, workpiece; 6, mark. Specific embodiments

[0026] The following will further describe in detail the embodiments of the present invention in combination with the accompanying drawings and embodiments. The following detailed description of the embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments, and covers any modifications, replacements, and improvements of parts, components, and connection methods without departing from the spirit of the present invention.

[0027] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will refer to the accompanying drawings and combine with embodiments to detail the present application.

[0028] Please refer to Figure 1 and Figure 2, in a first aspect, an embodiment of the present invention provides a tooling for slow tool servo machining of Zernike freeform surfaces, including: a tooling base 1 and a boss 2. The boss 2 is a cube, and the end face of the boss 2 is a square circumscribing the outer contour of the workpiece 5. When the workpiece 5 is installed on the boss 2, it is tangent to each side of the square through its outer contour, ensuring that the Z-axis of the workpiece 5 coincides with the Z-axis of the boss 2. The boss 2 is arranged on the tooling base 1. The tooling base 1 is a cylinder, and the end face of the tooling base 1 is a circle. The center of the circle coincides with the center of the square, ensuring that the Z-axis of the workpiece 5 coincides with the Z-axis of the tooling base 1. A circular groove 3 corresponding to the mark 6 on the workpiece 5 is opened at the center of one side of the square. By aligning the mark 6 on the workpiece 5 with the circular groove 3, the X and Y directions of the workpiece 5 can be ensured to be aligned with the X and Y directions of the tooling.

[0029] Please refer to Figure 2 and Figure 3 , in some embodiments, a plurality of through holes 4 are provided on the boss 2, and the through holes 4 penetrate through both the boss 2 and the tooling base 1. The through holes 4 are used to generate negative pressure by the spindle vacuum chuck when installing the workpiece 5 and the tooling on the spindle vacuum chuck of the machine tool. Through the through holes 4, the workpiece 5 is adsorbed, and at the same time, the tooling is pressed tightly against the spindle vacuum chuck.

[0030] In some embodiments, the through holes 4 are evenly distributed along the circumferences of circles with different diameters, making the force more uniform and reducing deformation.

[0031] In some embodiments, the circular groove 3 is located in the positive Y-axis direction of the boss 2, which is determined by setting the mark 6 in the positive Y-axis direction of the workpiece 5 during the rough machining stage for easy identification. When the mark 6 of the workpiece 5 is in other positions, it can be adjusted according to the mark 6 of the workpiece 5.

[0032] In some embodiments, the diameter of the circular groove 3 is 0.5 mm, which is convenient for identification during assembly and ensures accuracy at the same time.

[0033] In a second aspect, a method for aligning slow tool servo machining of Zernike freeform surfaces is provided, including the steps:

[0034] Set a mark 6 in the positive Y-axis direction of the workpiece 5 during the rough machining stage.

[0035] Align the mark 6 of the workpiece 5 with the circular groove 3, which can effectively confirm that the X and Y directions of the workpiece 5 correspond to the X and Y directions of the tooling, and the outer contour of the workpiece 5 is tangent to each side of the square, which can effectively confirm that the Z-axis of the workpiece 5 corresponds to the Z-axis of the tooling, making the coordinate systems of the workpiece 5 and the tooling completely coincide.

[0036] Start the spindle vacuum chuck of the machine tool to combine and fix the workpiece 5 with the tooling on the spindle vacuum chuck. The machine tool is an ultra-precision turning machine for slow tool servo machining.

[0037] Perform centering adjustment on the tooling. The specific centering adjustment is to press the measuring head of the dial indicator against the cylindrical surface of the tooling base 1, measure the outer circle runout of the cylindrical surface, adjust the position of the tooling to control the runout within 1 μm, and make the Z-axis of the machine tool coordinate system coincide with the Z-axis of the tooling.

[0038] Please refer to Figure 4 , perform X and Y direction adjustments on the tooling, measure and calculate the X-axis horizontal offset angle θ of the tooling on the spindle vacuum chuck. The specific X and Y direction adjustments are to press the measuring head of the dial indicator against the side of the boss 2 away from the circular groove 3, and by horizontally moving the X-axis, the display values of points A and B on the boss 2 are obtained as a and b respectively, and the vertical height H is calculated through the display values of points A and B. The calculation formula for the vertical height H is: H = b - a; Given that the side length of the boss 2 is a known value L, the calculation formula for the X-axis horizontal offset angle θ is:

[0039] Adjust the zero position of the C-axis of the machine tool according to the angle and direction of θ to make the tooling coincide with the coordinate system of the machine tool. Among them, adjusting the zero position of the C-axis of the machine tool only needs to input the angle and direction parameters of θ to the machine tool to complete, realizing high-precision and rapid adjustment of centering and X-axis parallelism during the secondary clamping process of free-form optical elements.

[0040] It should be clear that each embodiment in this specification is described in a progressive manner. For the same or similar parts between each embodiment, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. And, for the sake of simplicity, the detailed description of known method technologies is omitted here.

[0041] The above are only the embodiments of the present application and do not limit the present application. Without departing from the scope of the present invention, various changes and modifications can be made to the present application for those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A centering method for slow tool servo machining of Zernike freeform surfaces, characterized in that The tooling for slow tool servo machining using Zernike freeform surface, the tooling includes: a tooling base and a boss. The boss is a cube, and the end face of the boss is a square circumscribing the outer contour of the workpiece. When the workpiece is installed on the boss, its outer contour is tangent to each side of the square. The boss is arranged on the tooling base. The tooling base is a cylinder, and the end face of the tooling base is a circle. The center of the circle coincides with the center of the square. A circular groove corresponding to the mark on the workpiece is opened at the center of one side of the square. The alignment method includes the steps: Set a mark in the positive Y-axis direction of the workpiece during the rough machining stage. Align the mark of the workpiece with the circular groove, and make the outer contour of the workpiece tangent to each side of the square, so that the coordinate system of the workpiece coincides with that of the tooling. Start the spindle vacuum chuck of the machine tool to combine the workpiece with the tooling and fix it on the spindle vacuum chuck. Perform centering adjustment on the tooling. Adjust the tooling in the X and Y directions, measure and calculate the X-axis horizontal offset angle θ of the tooling on the spindle vacuum chuck; the specific X and Y direction adjustment is to abut the measuring head of the dial indicator against the side of the boss away from the circular groove, and by horizontally moving the X-axis, the display values of points A and B of the boss are obtained as a and b respectively, and the vertical height H is calculated through the display values of points A and B; the calculation formula for the vertical height H is: H = b - a; given that the side length of the boss is a known value L, the calculation formula for the X-axis horizontal offset angle θ is: Adjust the zero position of the C-axis of the machine tool through the angle and direction of θ to make the tooling coincide with the coordinate system of the machine tool.

2. The alignment method for Zernike free-form surface slow tool servo machining according to claim 1, wherein, A plurality of through holes are provided on the boss, and the through holes penetrate through the boss and the tooling base at the same time.

3. The alignment method for slow tool servo machining of a Zernike freeform surface according to claim 2, characterized in that The through holes are evenly distributed along the circumferences of circles with different diameters.

4. The alignment method for slow tool servo machining of a Zernike freeform surface according to claim 1, characterized in that, The circular groove is located in the positive Y-axis direction of the boss.

5. The alignment method for Zernike free-form surface slow tool servo machining according to claim 4, characterized in that, The diameter of the circular groove is 0.5 mm.

6. The alignment method for slow tool servo machining of a Zernike freeform surface according to claim 1, characterized in that, The specific centering adjustment is to abut the measuring head of the dial indicator against the cylindrical surface of the tooling base, measure the outer circle runout of the cylindrical surface, adjust the position of the tooling to control the runout within 1 μm, and make the Z-axis of the machine tool coordinate system coincide with the Z-axis of the tooling.

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