A motion unit positioning device and method for a thin-walled spherical shell surface microstructure ultra-precision controlled shaping machining system based on CCD vision

Abstract

The application provides a kind of based on CCD vision's thin-walled spherical shell surface microstructure ultra-precision controlled shaping processing system movement unit positioning device and method, belongs to the field of ultra-precision controlled shaping processing system alignment.To solve the problem that the initial space position of each movement unit of thin-walled spherical shell surface microstructure processing system cannot be efficiently calibrated, based on CCD vision, through program zero, establish machine tool coordinate system;Through program control each linear motion unit micro-feeding, complete tool setting, realize linear motion unit initial position alignment;The position coordinates of the feature points of the transition disc of the hydraulic B-axis rotary motion unit under three different rotation angles are captured by the CCD camera, and the space coordinates of the rotation center of the hydraulic B-axis rotary motion unit are obtained through data processing, to complete the initial position alignment of the hydraulic B-axis motion unit;The ball center of the tool ball head is captured by the CCD camera, the distance relative to the connecting line of the hydraulic B-axis rotation center and the included angle with the Z-axis moving direction are obtained, and the milling shaft motion unit positioning is completed.

Description

Technical Field

[0001] This invention relates to the field of motion unit positioning technology in ultra-precision shape control machining systems, and more specifically, to a motion unit positioning device and method for ultra-precision shape control machining systems for thin-walled spherical shell surface microstructures based on CCD vision. Background Technology

[0002] The aerospace, electronics, and biomedical industries are experiencing a surge in demand for high-precision, integrated, and complex micro-components. These components, primarily microcavities and thin-walled spherical shells, are on the millimeter scale and feature regularly distributed microstructures such as square cavities and micro-pits on their surfaces. They require sub-micrometer shape accuracy, nanometer-level surface roughness, and micrometer-level microstructure distribution errors. This necessitates the design of specialized ultra-precision shape control machining systems and auxiliary processes to meet the requirements for precision, surface quality, and distribution errors.

[0003] The machining of high-precision, regularly distributed micro-pitted structures across the entire surface of thin-walled spherical shells requires multi-axis linkage, placing higher precision demands on the ultra-precision form control machining system. The microstructure ultra-precision form control machining system consists of linear motion units and rotary motion units. The installation errors of each motion unit and their relative positional accuracy are crucial to ensuring the overall motion accuracy of the machining system. During machining, the spatial position of each motion unit needs to be precisely determined. Therefore, before machine tool operation, aligning the relative positions of each motion unit in the ultra-precision form control machining system within the machine tool coordinate system is particularly important to improve the motion accuracy and surface quality of the machining system.

[0004] Existing research mainly focuses on single-function two-axis and three-axis linkage ultra-precision manufacturing technologies. Research on multi-axis linkage, multi-motion unit coupling, and multi-process composite ultra-precision shape control machining technologies is limited, and methods and devices for aligning the positions of each motion unit are still in the technological gap. To meet the needs of practical engineering applications, there is an urgent need to design and develop a dedicated motion unit positioning method and device for ultra-precision shape control machining systems of thin-walled spherical shell surface microstructures, closely focusing on the high-precision machining requirements of the full-surface micro-pit structure of microspherical targets. This would reduce installation errors, improve the machining accuracy and surface quality of microstructures, and fill the technological gap. Summary of the Invention

[0005] The technical problem to be solved by this invention is:

[0006] To address the problem that the initial spatial positions of each motion unit in the existing multi-axis linkage ultra-precision shape control machining system for microstructures on thin-walled spherical shell surfaces cannot be efficiently calibrated.

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

[0008] This invention provides a motion unit positioning device for an ultra-precision shape control machining system for the surface microstructure of thin-walled spherical shells based on CCD vision. The device includes an X-axis linear motion unit, a Y-axis linear motion unit, a Z-axis linear motion unit, a hydraulic B-axis rotary motion unit, a workpiece C-axis rotary motion unit, a milling axis rotary motion unit, a horizontal CCD camera, a vertical CCD camera, and an inductive micrometer.

[0009] The X-axis linear motion unit and Z-axis linear motion unit are located in a horizontal plane and are arranged perpendicularly to each other. The Y-axis linear motion unit is located on the X-axis linear motion unit. The workpiece C-axis rotary motion unit is arranged on the Y-axis linear motion unit and is used to clamp the thin-walled spherical shell of the workpiece. The hydraulic B-axis rotary motion unit is arranged on the slide of the Z-axis linear motion unit through a transition plate. A hydraulic B-axis transition plate is connected to the hydraulic B-axis rotary motion unit. The hydraulic B-axis transition plate is arranged concentrically with the hydraulic B-axis rotary motion unit. The milling axis rotary motion unit is arranged on the hydraulic B-axis transition plate through a bushing. The tool clamping end of the milling axis rotary motion unit is used to clamp the tool. The horizontal CCD camera is arranged on the hydraulic B-axis transition plate through a micro-displacement platform. The vertical CCD camera is arranged on the Y-axis linear motion unit through a micro-displacement platform. The inductive micrometer is arranged on the hydraulic B-axis transition plate.

[0010] A method for positioning motion units in an ultra-precision shape control machining system for thin-walled spherical shell surface microstructures based on CCD vision includes the following steps:

[0011] S100, Positioning of Linear Motion Units: After the control machining system is powered on and communication is established, the program homing command is executed to move each linear motion unit to the origin of the machine tool coordinate system. Then, the program controls the micro-feed of each linear motion unit. Based on CCD vision, the tool setting of the linear motion unit is completed, and the initial position of the linear motion unit is aligned.

[0012] The positioning of the S200 hydraulic B-axis rotary motion unit is achieved by the microstructure ultra-precision shape control machining system control software executing a program homing command to control the hydraulic B-axis rotary motion unit to rotate to the zero point position of the grating; based on CCD vision, feature points are captured by horizontal and vertical CCD cameras to obtain the spatial coordinates of the hydraulic B-axis rotary motion unit, thus completing the initial positioning and alignment of the hydraulic B-axis rotary motion unit;

[0013] The positioning of the S300 milling axis rotary motion unit is achieved by the microstructure ultra-precision shape control machining system control software executing a program to control the hydraulic B-axis rotary motion unit to perform a zero-return operation. The cumulative rotation angle θ of the hydraulic B-axis rotary motion unit when the milling axis is aligned is obtained through an inductive micrometer. Based on CCD vision, the linear motion unit is moved to position the tool at the center of the field of view of the vertical CCD camera, and the movement distance Δx1 of the X-axis linear motion unit and the movement distance Δz1 of the Z-axis linear motion unit are obtained, thus completing the positioning of the milling axis rotary motion unit.

[0014] Furthermore, step S100 specifically includes:

[0015] S110. Power on the ultra-precision shape control machining system, establish communication between the host computer and the controller, move the X-axis linear motion unit, Y-axis linear motion unit and Z-axis linear motion unit to the zero return range, and enable the X-axis linear motion unit, Y-axis linear motion unit and Z-axis linear motion unit.

[0016] S120: The microstructure ultra-precision shape control machining system control software executes the program zero-return operation, moving the X-axis linear motion unit, Y-axis linear motion unit and Z-axis linear motion unit to the zero point position, and establishing the machine tool coordinate system;

[0017] S130. The micro-feed motion of each axis is controlled by the micro-structure ultra-precision shape control machining system control software. The movement of the linear motion unit in the YOZ plane is observed by a horizontal high-resolution CCD camera, and the movement of the linear motion unit in the XOZ plane is observed by a vertical CCD camera. Based on CCD vision, the tool setting operation of the linear motion unit is completed, and the movement distance Δx of the X-axis linear motion unit, the movement distance Δy of the Y-axis linear motion unit, and the movement distance Δz of the Z-axis linear motion unit are recorded by the micro-structure ultra-precision shape control machining system control software.

[0018] Furthermore, step S130 specifically includes:

[0019] S131. When setting the tool based on CCD vision, the contact between the X-axis linear motion unit and the Z-axis linear motion unit in the plane parallel to the YOZ plane of the machine tool is observed by a horizontal CCD camera. The linear motion unit is adjusted so that the C-axis rotary motion unit of the workpiece fixed on the Y-axis linear motion unit is approximately at the same height as the milling axis in the plane parallel to the YOZ plane of the shape control machining equipment. The linear motion unit is adjusted so that the thin-walled spherical shell workpiece is approximately close to the tool.

[0020] S132. When setting the tool based on CCD vision, the contact between the X-axis linear motion unit and the Z-axis linear motion unit in the plane parallel to the XOZ plane of the machine tool is observed by a horizontal CCD camera. The linear motion unit is adjusted so that the C-axis rotary motion unit of the workpiece and the milling axis are approximately collinear in the plane parallel to the XOZ plane of the machine tool. At the same time, the position calibration of the C-axis rotary motion unit of the workpiece is completed.

[0021] S133. Based on CCD vision, the program controls the micro-feed of each linear motion unit. Through image observation, the precise tool setting of the thin-walled spherical shell workpiece and the tool is completed. The movement distances Δx, Δy and Δz of the X-axis linear motion unit, Y-axis linear motion unit and Z-axis linear motion unit are recorded.

[0022] Furthermore, step S200 specifically includes:

[0023] S210. The hydraulic B-axis rotary motion unit is controlled by the program to perform a zero-return operation, so that the hydraulic B-axis rotary motion unit returns to the zero point position of the grating, and the random feature point P in the circumferential area of ​​the hydraulic B-axis transition disk is marked. B The program moves the X-axis linear motion unit, Y-axis linear motion unit, and Z-axis linear motion unit, causing the vertical CCD camera to capture the circumferential feature point P of the hydraulic B-axis transition disk. B And obtain the coordinate parameters of the feature point at this time;

[0024] S220, the moving linear motion unit, observed through a vertical CCD camera, makes the circumferential feature point P B Located at the center of the vertical CCD camera's field of view, the distance traveled by the X-axis linear motion unit and the Z-axis linear motion unit in the control software is obtained, which is P. B The coordinates P when the point is at zero position B1 (x1,z1);

[0025] S230, the program controls each linear axis motion unit to move to a safe position, controls the hydraulic B-axis rotary motion unit to rotate clockwise by a random angle α, the program moves the X-axis linear motion unit, Y-axis linear motion unit, and Z-axis linear motion unit, and observes through a vertical CCD camera, so that feature point P B Located at the center of the vertical CCD camera's field of view, capturing the B-axis circumferential feature point P. B Obtain feature point P B The coordinates of point P when it is at angle α B2 (x2,z2);

[0026] S240, the program controls each linear axis motion unit to move to a safe position, controls the hydraulic B-axis rotary motion unit to return to the grating zero point, and randomly rotates counterclockwise by an angle β. The program moves the X-axis linear motion unit, Y-axis linear motion unit, and Z-axis linear motion unit, and observes through a vertical CCD camera, so that feature point P... B Located at the center of the vertical CCD camera's field of view, capturing the B-axis circumferential feature point P. B Obtain feature point P B The coordinates of point P when it is at angle β B3 (x3, z3);

[0027] S250, the coordinates P of the feature point set P of the circumferential edge of the hydraulic B-axis transition plate when the hydraulic B-axis rotary motion unit is at the zero position, clockwise α-angle position, and counterclockwise β-angle position. B1 (x1,z1),P B2 (x2,z2) and P B3 (x3, z3) is used to fit the center of the circumferential edge feature point of the hydraulic B-axis transition plate through the position calibration algorithm, and then obtain the center coordinates, that is, the rotation center position coordinates of the hydraulic B-axis rotary motion unit, thus completing the positioning of the hydraulic B-axis rotary motion unit.

[0028] Furthermore, step S250 specifically includes:

[0029] S251. Taking the rotation center of the hydraulic B-axis rotary motion unit as the reference, obtain the distribution of the feature points of the circumferential edge of the hydraulic B-axis transition plate relative to the rotation center of the hydraulic B-axis rotary motion unit when the hydraulic B-axis rotary motion unit is at three positions: zero point, clockwise angle α, and counterclockwise angle β.

[0030] S252. Based on the position calibration algorithm, extract the positions of feature points in the circumferential region of the hydraulic B-axis transition plate relative to the B-axis rotation center when they are in three different positions; using P... B1 Establish a position calibration coordinate system X with the origin as the origin. c O c Z c , feature point P B1 P B2 and P B3 Transform to the position calibration coordinate system to obtain P B2 and P B3 In coordinate system X c O c Z c The coordinates in the figure are P B2 (x 2-0 ,z 2-0 ) and P B3 (x 3-0 ,z 3-0 Specifically:

[0031]

[0032] S253, in coordinate system X c O c Z c In the middle, for point O c (0,0) and P B2 (x 2-0 ,z 2-0 O was obtained by numerical calculation method. c P B2 Equation of the line:

[0033]

[0034] S253, in coordinate system X c O c Z c In the middle, for point O c (0,0) and P B3 (x 3-0 ,z 3-0 O was obtained by numerical calculation method. c P B3 Equation of the line:

[0035]

[0036] S254, by O c P B2 The equation of the line containing the line is given, which gives line segment O. c P B2 Midpoint P m1 (x 2-0 / 2,z 2-0 / 2) and O c P B2 The slope of the perpendicular line k1 = -z 2-0 / x 2-0 Thus, line segment O is obtained. c P B2 Equation of line l1 containing the perpendicular bisector:

[0037]

[0038] S255, by O c P B3 The equation of the line containing the line is given, which gives line segment O. c P B3 Midpoint P m2 (x 3-0 / 2,z 3-0 / 2) and O c P B3 The slope of the perpendicular line k2 = -z 3-0 / x3-0 Thus, line segment O is obtained. c P B3 The equation of line l2 containing the perpendicular bisector is:

[0039]

[0040] S256. Solve the equations (4) and (5) simultaneously to find the intersection point P of lines l1 and l2. o (x0, z0) coordinates:

[0041]

[0042] The coordinates P0(x0,z0) of the intersection point of lines l1 and l2 are in the position calibration coordinate system X. c O c Z c The parameters below, whose coordinates P(x,z) relative to the machine tool coordinate system, are:

[0043]

[0044] Combining formulas (1), (6), and (7), the initial position coordinates of the hydraulic B-axis rotary motion unit are obtained:

[0045]

[0046] Complete the initial position calibration of the hydraulic B-axis rotary motion unit.

[0047] Furthermore, step S300 specifically includes:

[0048] S310, The program controls the hydraulic B-axis rotary motion unit to perform a zero-return operation. By moving the Z-axis linear motion unit, and using an inductive micrometer to align the milling axis placed on the hydraulic B-axis rotary motion unit, the milling axis is made parallel to the moving direction of the Z-axis linear motion unit. The cumulative rotation angle θ of the hydraulic B-axis rotary motion unit when the milling axis is aligned is obtained.

[0049] S320: The program moves each linear motion unit and observes the feature points of the end tool of the milling axis through the vertical CCD camera, so that the center of the ball end mill is located in the center of the CCD field of view. The X-axis linear motion unit movement distance Δx1 and the Z-axis linear motion unit movement distance Δz1 in the control software are obtained to complete the positioning of the milling axis rotary motion unit.

[0050] Furthermore, α > 40°, β > 40°.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] This invention provides a motion unit positioning device and method for a CCD vision-based ultra-precision shape control machining system for microstructures on the surface of thin-walled spherical shells. Based on high-resolution CCD vision, the initial positions of the linear motion unit and rotary motion unit of the ultra-precision shape control machining system are aligned to reduce the accumulation of machining errors and meet the high-precision machining requirements such as micron-level shape accuracy, nanometer-level surface roughness, and micron-level microstructure distribution error of microstructures on the surface of thin-walled spherical shells.

[0053] A 26-megapixel high-resolution CCD camera is used to observe the contact between the workpiece and the tool setting area. Combined with a linear motion unit with a positioning accuracy better than 0.4μm / full stroke, tool setting is adjusted, which can accurately capture the spatial coordinates of feature structures / feature points.

[0054] A high-precision inductive micrometer with a resolution of 0.01μm and an accuracy of 0.1μm is used to perform high-precision and efficient alignment of the milling axis, providing an important zero-position reference for subsequent milling axis position calibration;

[0055] It has a certain degree of universality, and is not only suitable for the initial position calibration of motion units in ultra-precision shape control machining systems for microstructures on thin-walled spherical shell surfaces, but can also be further extended to the positioning and alignment of linear or rotary motion units in conventional multi-axis machine tools, further ensuring the machining accuracy of machine tools. Attached Figure Description

[0056] Figure 1 This is a perspective view of a motion unit positioning device for an ultra-precision shape control machining system for the surface microstructure of a thin-walled spherical shell based on CCD vision, as described in an embodiment of the present invention.

[0057] Figure 2 This is a schematic diagram showing the relative positions of a thin-walled spherical shell workpiece and a cutting tool in a plane parallel to the YOZ plane according to an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram showing the relative positions of a thin-walled spherical shell workpiece and a cutting tool in a plane parallel to the XOZ plane in an embodiment of the present invention;

[0059] Figure 4 In this embodiment of the invention, the feature point P is located in the circumferential region of the hydraulic B-axis transition disc. B A schematic diagram of the spatial position when at zero position;

[0060] Figure 5 In this embodiment of the invention, the feature point P is located in the circumferential region of the hydraulic B-axis transition disc. B A schematic diagram of the spatial position when at a clockwise angle α;

[0061] Figure 6 In this embodiment of the invention, the feature point P is located in the circumferential region of the hydraulic B-axis transition disc. B Schematic diagram of the spatial position at a counterclockwise β angle;

[0062] Figure 7 In this embodiment of the invention, the feature point P is located in the circumferential region of the hydraulic B-axis transition disc. B A schematic diagram of the spatial position at zero point, clockwise angle α, and counterclockwise angle β;

[0063] Figure 8 In this embodiment of the invention, the feature point P is located in the circumferential region of the hydraulic B-axis transition disc. B A schematic diagram of the spatial position at zero point, clockwise angle α, and counterclockwise angle β.

[0064] Explanation of reference numerals in the attached figures:

[0065] 1. Z-axis linear motion unit; 2. Hydraulic B-axis rotary motion unit; 3. Hydraulic B-axis transition plate; 4. Milling axis rotary motion unit; 5. Cutting tool; 6. Horizontal CCD camera; 7. Vertical CCD camera; 8. Workpiece thin-walled spherical shell; 9. Workpiece C-axis rotary motion unit; 10. Y-axis linear motion unit; 11. X-axis linear motion unit. Detailed Implementation

[0066] In the description of this invention, it should be noted that the terms used in the various embodiments, such as "upper," "lower," "front," "rear," "left," and "right," which indicate orientation, are only used to simplify the description of the positional relationships based on the accompanying drawings and do not mean that the components and devices referred to must be operated in accordance with the specific orientations and defined operations, methods, and structures in the specification. Such directional terms do not constitute a limitation of this invention.

[0067] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0068] Specific Implementation Plan 1: Combining Figures 1 to 8 As shown, this invention provides a motion unit positioning device for an ultra-precision shape control machining system for the microstructure of thin-walled spherical shell surfaces based on CCD vision. The device includes an X-axis linear motion unit 11, a Y-axis linear motion unit 10, a Z-axis linear motion unit 1, a hydraulic B-axis rotary motion unit 2, a workpiece C-axis rotary motion unit 9, a milling axis rotary motion unit 4, a horizontal CCD camera 6, a vertical CCD camera 7, and an inductive micrometer.

[0069] The X-axis linear motion unit 11 and Z-axis linear motion unit 1 are located in a horizontal plane and are arranged perpendicularly to each other. The Y-axis linear motion unit 10 is located on the X-axis linear motion unit 11. The workpiece C-axis rotary motion unit 9 is mounted on the Y-axis linear motion unit 10 by screws. The workpiece C-axis rotary motion unit 9 is used to clamp the thin-walled spherical shell 8 of the workpiece by an adsorption fixture. The hydraulic B-axis rotary motion unit 2 is mounted on the slide of the Z-axis linear motion unit 1 by a transition plate. The hydraulic B-axis rotary motion unit 2 is connected to the hydraulic B-axis transition plate 3 by screws. The hydraulic B-axis transition plate 3 is concentrically arranged with the hydraulic B-axis rotary motion unit 2. The milling axis rotary motion unit 4 is mounted on the hydraulic B-axis transition plate 3 by a bushing. The tool clamping end of the milling axis rotary motion unit 4 is used to clamp the tool 5 by pneumatic clamping. The horizontal CCD camera 6 is mounted on the hydraulic B-axis transition plate by a micro-displacement platform. The vertical CCD camera 7 is mounted on the Y-axis linear motion unit 10 by a micro-displacement platform. The inductive micrometer is mounted on the hydraulic B-axis transition plate 3.

[0070] Specific Implementation Plan Two: Combining Figures 1 to 8 As shown, this invention provides a method for positioning motion units in a CCD vision-based ultra-precision shape control machining system for microstructures on the surface of thin-walled spherical shells, comprising the following steps:

[0071] S100. Positioning of linear motion units: After the control machining system is powered on and communication is established, the program's homing command is executed to move each linear motion unit to the origin of the machine tool coordinate system. Then, the program controls the micro-feed of each linear motion unit. Based on CCD vision, tool setting of the linear motion units is completed, achieving the initial positioning of the linear motion units. Specifically, this includes:

[0072] S110. Power on the ultra-precision shape control machining system, establish communication between the host computer and the controller, move the X-axis linear motion unit 11, the Y-axis linear motion unit 10 and the Z-axis linear motion unit 1 to the zero-return range, and enable the X-axis, Y-axis and Z-axis.

[0073] The X-axis linear motion unit 11, Y-axis linear motion unit 10, and Z-axis linear motion unit 1 are all symmetrically divided into positive and negative intervals throughout their entire motion stroke. The direction of the X-axis linear motion unit 11 away from the operating viewpoint is the positive motion direction, the upward direction of the Y-axis linear motion unit 10 is the positive motion direction, and the direction of the Z-axis linear motion unit 1 closer to the Y-axis linear motion unit 10 is the positive motion direction. The zero-return intervals of the X-axis linear motion unit 11, Y-axis linear motion unit 10, and Z-axis linear motion unit 1 are, in order, the negative intervals of the negative motion direction of the X-axis linear motion unit 11, the negative intervals of the negative motion direction of the Y-axis linear motion unit 10, and the negative intervals of the negative motion unit of the Z-axis linear motion unit 1.

[0074] The positioning accuracy of the linear motion unit is better than 0.4μm / full stroke;

[0075] S120: The microstructure ultra-precision shape control machining system control software executes the program zero-return operation, moving the X-axis linear motion unit 11, Y-axis linear motion unit 10 and Z-axis linear motion unit 1 to the zero point position, and establishing the machine tool coordinate system;

[0076] The control software for the microstructure ultra-precision shape control machining system is independently developed based on the C# language under the .NET framework. It can realize fast, efficient and intelligent control of multi-axis linkage machining of microstructure surfaces. The control software for the shape control machining system has applied for software copyright, iCMP, registration number: 2024SR0139826 (certificate issued). When executing the program to return to zero, the control software calls the terminal command "#*hm", (* = 1, 2, 3, representing X-axis linear motion unit 11, Y-axis linear motion unit 10 and Z-axis linear motion unit 1 respectively) to control X-axis linear motion unit 11, Y-axis linear motion unit 10 and Z-axis linear motion unit 1 to move to the zero point position.

[0077] S130. The micro-feed motion of each axis is controlled by the micro-structure ultra-precision shape control machining system control software. The movement of the linear motion unit in the YOZ plane is observed by a horizontal high-resolution CCD camera, and the movement of the linear motion unit in the XOZ plane is observed by a vertical CCD camera 7. Based on CCD vision, the tool setting operation of the linear motion unit is completed, and the movement distance Δx of the X-axis linear motion unit 11, the movement distance Δy of the Y-axis linear motion unit 10, and the movement distance Δz of the Z-axis linear motion unit 1 are recorded by the micro-structure ultra-precision shape control machining system control software. Specifically, this includes:

[0078] S131, Combination Figure 2 As shown, during CCD vision-based tool setting, a 26-megapixel high-resolution horizontal CCD camera 6 is used to observe the contact between the X-axis linear motion unit 11 and the Z-axis linear motion unit 1 in a plane parallel to the machine tool's YOZ plane. The linear motion units are adjusted so that the workpiece C-axis rotary motion unit 9, which is fixed on the Y-axis linear motion unit 10, and the milling axis are approximately at the same height in a plane parallel to the shape control machining equipment's YOZ plane. The linear motion units are also adjusted so that the thin-walled spherical shell workpiece is approximately close to the tool 5.

[0079] S132, Combination Figure 3As shown, during CCD vision-based tool setting, a 26-megapixel high-resolution horizontal CCD camera 6 is used to observe the contact between the X-axis linear motion unit 11 and the Z-axis linear motion unit 1 in a plane parallel to the XOZ plane of the machine tool. The linear motion units are adjusted so that the workpiece C-axis rotary motion unit 9 and the milling axis are approximately collinear in a plane parallel to the XOZ plane of the machine tool, and the position calibration of the workpiece C-axis rotary motion unit 9 is completed at the same time.

[0080] S133. Based on CCD vision, the program controls the micro-feed of each linear motion unit. Through image observation, the workpiece thin-walled spherical shell 8 and the tool 5 are precisely set. The movement distances Δx, Δy and Δz of the linear motion units X-axis linear motion unit 11, Y-axis linear motion unit 10 and Z-axis linear motion unit 1 are recorded.

[0081] The S200 hydraulic B-axis rotary motion unit 2 is positioned and aligned by the microstructure ultra-precision shape control machining system control software executing a homing command to rotate it to the grating zero point position. Based on CCD vision, a high-resolution CCD camera captures feature points to obtain the spatial coordinates of the hydraulic B-axis rotary motion unit 2, completing the initial position alignment and positioning of the hydraulic B-axis rotary motion unit 2. Specifically, this includes:

[0082] S210. The hydraulic B-axis rotary motion unit 2 is controlled by the program to perform a zero-return operation, so that the hydraulic B-axis rotary motion unit 2 returns to the zero point of the grating, and marks the random feature point P in the circumferential area of ​​the hydraulic B-axis transition disk 3. B The program moves the X-axis linear motion unit 11, the Y-axis linear motion unit 10, and the Z-axis linear motion unit 1, so that the vertical CCD camera 7 captures the circumferential feature point P of the hydraulic B-axis transition disk 3. B And obtain the coordinate parameters of the feature point at this time;

[0083] When performing the zero-return operation of the hydraulic B-axis rotary motion unit 2, the control software calls the terminal command "#4hm" to control the hydraulic B-axis rotary motion unit 2 to rotate to the zero position;

[0084] The circumferential area of ​​the hydraulic B-axis transition plate 3 and the internal surface of the hydraulic B-axis transition plate 3 that connects to the hydraulic B-axis rotary motion unit 2 have good cylindricity to ensure that the hydraulic B-axis transition plate 3 and the hydraulic B-axis rotary motion unit 2 have good coaxiality.

[0085] The feature point P in the circumferential region of the hydraulic B-axis transition disk 3 B A set of marker points marked by humans and located on the circumferential edge of the transition disk, used for capture by the vertical CCD camera 7, and can rotate concentrically with the hydraulic B-axis rotary motion unit 2;

[0086] S220, combined Figure 4As shown, the linear motion unit moves, and through observation by the vertical CCD camera 7, the circular feature point P is observed. B Located at the center of the field of view of the vertical CCD camera 7, the moving distance of the X-axis linear motion unit 11 and the Z-axis linear motion unit 1 in the control software is obtained, which is P. B The coordinates P when the point is at zero position B1 (x1,z1);

[0087] S230, combined Figure 5 As shown, the program controls each linear axis motion unit to move to a safe position, controls the hydraulic B-axis rotary motion unit 2 to rotate clockwise by a random angle α, where α > 40°, the program moves the X-axis linear motion unit 11, the Y-axis linear motion unit 10 and the Z-axis linear motion unit 1, and observes through the vertical CCD camera 7, so that the feature point P B Located at the center of the field of view of the vertical CCD camera 7, capturing the B-axis circumferential feature point P. B Obtain feature point P B The coordinates of point P when it is at angle α B2 (x2,z2);

[0088] When the program controls the hydraulic B-axis rotary motion unit 2 to rotate clockwise by a random angle α, the hydraulic B-axis transition plate and its feature points also rotate accordingly.

[0089] S240, combined Figure 6 As shown, the program controls each linear axis motion unit to move to a safe position, controls the hydraulic B-axis rotary motion unit 2 to return to the grating zero point, and randomly rotates counterclockwise by an angle β. Where β > 40°, the program moves the X-axis linear motion unit 11, Y-axis linear motion unit 10, and Z-axis linear motion unit 1, and observes through the vertical CCD camera 7, making the feature point P... B Located at the center of the field of view of the vertical CCD camera 7, capturing the B-axis circumferential feature point P. B Obtain feature point P B The coordinates of point P when it is at angle β B3 (x3, z3);

[0090] When the program controls the hydraulic B-axis rotary motion unit 2 to return to the grating zero point and rotates counterclockwise by a random angle β, the hydraulic B-axis transition plate and its feature points also rotate accordingly.

[0091] S250, the coordinates P of the feature point set P of the circumferential edge of the hydraulic B-axis transition disk 3 when the hydraulic B-axis rotary motion unit 2 is at the zero point position, the clockwise α angle position, and the counterclockwise β angle position. B1 (x1,z1),P B2 (x2,z2) and P B3(x3, z3), using a position calibration algorithm, the center of the circumference of the feature point on the circumferential edge of the hydraulic B-axis transition disk 3 is fitted, thus obtaining the center coordinates, which are the rotation center position coordinates of the hydraulic B-axis rotary motion unit 2, completing the positioning of the hydraulic B-axis rotary motion unit 2, specifically including:

[0092] S251, combined Figure 7 As shown, with the rotation center of the hydraulic B-axis rotary motion unit 2 as the reference, the distribution diagram of the feature points of the circumferential edge of the hydraulic B-axis transition plate 3 relative to the rotation center of the hydraulic B-axis rotary motion unit 2 is obtained when the hydraulic B-axis rotary motion unit 2 is at the zero point, clockwise angle α, and counterclockwise angle β.

[0093] Among them, P B1 O represents the feature point P in the circumferential region of the hydraulic B-axis transition disk. B1 The line connecting the rotation center O of axis B; P B2 O represents the feature point P in the circumferential region of the hydraulic B-axis transition disk. B2 The line connecting the rotation center O of axis B; P B3 O represents the feature point P in the circumferential region of the hydraulic B-axis transition disk. B3 The line connecting the rotation center O of axis B;

[0094] S252, combined Figure 8 As shown in (a), based on the position calibration algorithm, the positions of feature points in the circumferential region of the hydraulic B-axis transition plate 3 relative to the B-axis rotation center are extracted when they are in three different positions; combined with Figure 8 As shown in (b), with P B1 Establish a position calibration coordinate system X with the origin as the origin. c O c Z c , feature point P B1 P B2 and P B3 Transform to the position calibration coordinate system to obtain P B2 and P B3 In coordinate system X c O c Z c The coordinates in the figure are P B2 (x 2-0 ,z 2-0 ) and P B3 (x 3-0 ,z 3-0 Specifically:

[0095]

[0096] S253, in coordinate system X c O c Z c In the middle, for point Oc (0,0) is P B1 and P B2 (x 2-0 ,z 2-0 O was obtained by numerical calculation method. c P B2 Equation of the line:

[0097]

[0098] S253, in coordinate system X c O c Z c In the middle, for point O c (0,0) and P B3 (x 3-0 ,z 3-0 O was obtained by numerical calculation method. c P B3 Equation of the line:

[0099]

[0100] S254, by O c P B2 The equation of the line containing the line is given, which gives line segment O. c P B2 Midpoint P m1 (x 2-0 / 2,z 2-0 / 2) and O c P B2 The slope of the perpendicular line k1 = -z 2-0 / x 2-0 Thus, line segment O is obtained. c P B2 Equation of line l1 containing the perpendicular bisector:

[0101]

[0102] S255, by O c P B3 The equation of the line containing the line is given, which gives line segment O. c P B3 Midpoint P m2 (x 3-0 / 2,z 3-0 / 2) and O c P B3 The slope of the perpendicular line k2 = -z 3-0 / x 3-0 Thus, line segment O is obtained. c P B3 The equation of line l2 containing the perpendicular bisector is:

[0103]

[0104] S256. Solve the equations (4) and (5) simultaneously to find the intersection point P of lines l1 and l2. o (x0, z0) coordinates:

[0105]

[0106] The coordinates P0(x0,z0) of the intersection point of lines l1 and l2 are in the position calibration coordinate system X. c O c Z c The parameters below, whose coordinates P(x,z) relative to the machine tool coordinate system, are:

[0107]

[0108] Combining formulas (1), (6), and (7), the initial position coordinates of the hydraulic B-axis rotary motion unit 2 can be obtained:

[0109]

[0110] Complete the initial position calibration of hydraulic B-axis rotary motion unit 2;

[0111] Position alignment of the S300 milling axis rotary motion unit specifically includes:

[0112] S310, The program controls the hydraulic B-axis rotary motion unit 2 to perform a zero-return operation. By moving the Z-axis linear motion unit 1, and using an inductive micrometer to align the milling axis placed on the hydraulic B-axis rotary motion unit 2, the milling axis is parallel to the moving direction of the Z-axis linear motion unit 1.

[0113] After the hydraulic B-axis rotary motion unit 2 completes the zero-return operation, there is an angle between the milling axis axis and the moving direction of the Z-axis linear motion unit 1. The electro-inductive micrometer has a resolution of 0.01μm and an accuracy of 0.1μm. By repeatedly moving the Z-axis linear motion unit 1, the rotation angle of the hydraulic B-axis rotary motion unit 2 is slightly adjusted to obtain the cumulative rotation angle θ of the hydraulic B-axis rotary motion unit 2 when the milling axis is aligned.

[0114] S320: The program moves each linear motion unit and observes the feature points of the end tool of the milling axis, i.e., the ball end mill, through the vertical CCD camera 7, so that the center of the ball end mill is located at the center of the CCD field of view. The movement distance Δx1 of the X-axis linear motion unit 11 and the movement distance Δz1 of the Z-axis linear motion unit 1 in the control software are obtained, which are the initial positions before the milling axis is processed, and the positioning of the milling axis rotary motion unit 4 is completed.

[0115] The other combinations and connections in this implementation scheme are the same as in Specific Implementation Scheme 1.

[0116] experiment

[0117] Step 1: Ensure the hardware connection is correct, power on the machine tool to establish communication, enable each axis, execute the program's zero-return command, and move each linear motion unit to the zero point position of the grating;

[0118] Step 2: The program controls each linear axis motion unit to perform micro-feed tool setting operation. The horizontal CCD camera 6 observes the movement of each linear motion unit in the YOZ plane, and the vertical CCD camera 7 observes the movement of the linear motion unit in the XOZ plane. Based on CCD vision, the tool setting is completed when the contact area between the tool 5 and the workpiece is observed until chips are generated. The X-axis movement distance Δx = 30.264, the Y-axis movement distance Δy = 8.763, and the Z-axis movement distance Δz = 56.283 are obtained.

[0119] Step 3: The program controls the hydraulic B-axis rotary motion unit 2 to perform a zero-return operation. The vertical CCD camera 7 acquires the coordinates P of the feature point in the circumferential region of the hydraulic B-axis transition disk 3 when it is at the zero position. B1 (x1,z1)=P B1 (12.263, 36.894); The hydraulic B-axis rotary motion unit 2 is controlled to rotate clockwise by a random angle α (α>40°), and the coordinates P of the feature point of the hydraulic B-axis transition disk 3 are obtained by the vertical CCD camera 7. B2 (x2,z2)=P B2 (38.973, 56.252); The hydraulic B-axis rotary motion unit 2 is controlled to return to zero and rotate counterclockwise by an angle β (β>40°), and the coordinates P of the feature point of the hydraulic B-axis transition disk 3 are obtained by the vertical CCD camera 7. B3 (x3,z3)=P B3 (-10.483, 52.028);

[0120] Step 4: Obtain the X coordinate system using the coordinate system calibration algorithm. c O c Z c China P B1 (x 1-0 ,z 1-0 ) = P B1 (0,0),P B2 (x 2-0 ,z 2-0 )=

[0121] P B2 (26.71, 19.358), P B3 (x 3-0 ,z 3-0 ) = P B3 Substituting (-33.506, 15.134) into formula (2), we obtain O.c P B2 Equation of the line:

[0122] x = 1.34z (9)

[0123] Substituting into formula (3), we obtain O c P B3 Equation of the line:

[0124] x = -2.21z (10)

[0125] Substitute into formula (4) to obtain line segment O. c P B2 Equation of line l1 containing the perpendicular bisector:

[0126] x = -0.72z + 20.324 (11)

[0127] Substitute into formula (5) to obtain line segment O. c P B3 The equation of line l2 containing the perpendicular bisector is:

[0128] x = 0.45z - 20.158 (12)

[0129] Combining formulas (11) and (12), and substituting them into formula (6), we obtain the coordinates of the intersection point P0(x0,z0) of lines l1 and l2:

[0130] P0(x0,z0)=P0(0.73,8.67) (13)

[0131] Step 5: From coordinate system X c O c Z c Substitute the coordinates of the hydraulic B-axis rotation center into formula (8) to obtain the coordinates of the hydraulic B-axis rotation center in the machine tool coordinate system:

[0132]

[0133] Complete the initial position calibration of hydraulic B-axis rotary motion unit 2;

[0134] Step 6: The program controls the hydraulic B-axis rotary motion unit 2 to perform a zero-return operation, and uses an inductive micrometer to align the milling axis with a dial indicator, so that the milling axis is parallel to the movement direction of the Z-axis linear motion unit 1, and obtains the cumulative rotation angle θ of the hydraulic B-axis rotary motion unit 2 when the milling axis is aligned, which is 45.7373°.

[0135] Step 7: The program moves each linear motion unit and observes the feature point of the ball end mill at the end of the milling axis through the vertical CCD camera 7 to move it to the center of the CCD field of view, and obtains the X-axis movement distance Δx1 = 6.524 and the Z-axis movement distance Δz1 = 29.875, which are the initial positions of the milling axis motion units.

[0136] Step 8: Based on the above analysis and calculations, the calibration distances / angles of each axis before machining in the ultra-precision shape control machining system for the microstructure of the thin-walled spherical shell surface are as follows: X-axis linear motion unit 11: 30.264; Y-axis linear motion unit 10: 8.763; Z-axis linear motion unit 1: 56.283; the spatial coordinates of the hydraulic B-axis rotation center (x,z) = (12.993, 45.562), and the alignment angle of hydraulic B-axis rotation motion unit 2 is 45.7373°. This completes the efficient calibration of the initial positions of each motion unit in the shape control machining system, providing an important characterization for the quality of the machined surface.

[0137] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A positioning method for a motion unit positioning device of a thin-walled spherical shell surface microstructure ultra-precision controlled-shape machining system based on CCD vision, characterized in that, The method comprises the following steps: S100, position alignment of the linear motion unit, after the power-on communication of the controlled shape machining system is established, the zero return instruction of the program is executed to make each linear motion unit move to the origin position of the machine tool coordinate system, and then the micro-feeding of each linear motion unit is controlled by the program, the tool setting of the linear motion unit is completed based on the CCD vision, and the initial position alignment of the linear motion unit is realized; S200, position alignment of the hydraulic B-axis rotary motion unit (2), the zero return instruction of the program is executed by the micro-structure ultra-precision controlled shape machining system control software to control the hydraulic B-axis rotary motion unit (2) to rotate to the grating zero point position; the feature points are captured by the horizontal CCD camera (6) and the vertical CCD camera (7) based on the CCD vision, the spatial position coordinates of the hydraulic B-axis rotary motion unit (2) are obtained, the initial position alignment and positioning of the hydraulic B-axis rotary motion unit (2) are completed; comprise, S210, execute the zero operation by program control hydraulic B-axis rotary motion unit (2), make hydraulic B-axis rotary motion unit (2) return to grating zero point position, mark the random feature point P of hydraulic B-axis transition disc (3) circumferential area B , program moves X-axis linear motion unit (11), Y-axis linear motion unit (10) and Z-axis linear motion unit (1), so that vertical CCD camera (7) captures the circumferential feature point P of hydraulic B-axis transition disc (3) B , and obtain the feature point coordinate parameters at this time; S220, moving linear motion unit, through the vertical CCD camera (7) observation, so that the circular feature point P B Located in the vertical CCD camera (7) field of view center, get control software in X-axis linear motion unit (11), Z-axis linear motion unit (1) moving distance, that is, P B Point in the zero position coordinates ; S230, program control each linear axis motion unit motion to the safe position, control the hydraulic B axis rotation motion unit (2) clockwise rotate random α angle, program moves X axis linear motion unit (11), Y axis linear motion unit (10) and Z axis linear motion unit (1), and observes through vertical CCD camera (7), so that the feature point P B Located in the field of view center of vertical CCD camera (7), capture B axis circumference feature point P B , get the coordinates of feature point P B Point at α angle ; S240, program control each linear axis motion unit motion to the safe position, control the hydraulic B axis rotation motion unit (2) to return to the grating zero point, and rotate β angle randomly counterclockwise, the program moves X axis linear motion unit (11), Y axis linear motion unit (10) and Z axis linear motion unit (1), and observes through the vertical CCD camera (7), so that the feature point P B Located in the field of view center of the vertical CCD camera (7), capture B axis circumferential feature point P B , get the coordinates of the feature point P B Point at β angle ; S250, the circumferential edge feature point set coordinates of the hydraulic B shaft transition disc (3) when the hydraulic B shaft rotary motion unit (2) is at the zero position, the clockwise α angle position and the counterclockwise β angle position and The circumferential center of the circumferential edge feature points of the hydraulic B shaft transition disc (3) is fitted through a position calibration algorithm, and then the circumferential center coordinates, i.e. the rotary center position coordinates of the hydraulic B shaft rotary motion unit (2), are obtained, and the positioning of the hydraulic B shaft rotary motion unit (2) is completed; specifically comprise, S251, taking the rotation center of the hydraulic B-axis rotary motion unit (2) as the reference, the distribution of the circumferential edge feature points of the hydraulic B-axis transition disc (3) relative to the rotation center of the hydraulic B-axis rotary motion unit (2) when the hydraulic B-axis rotary motion unit (2) is at the zero point, the clockwise α angle and the counterclockwise β angle three positions is obtained; S252, based on the position calibration algorithm, the position of the characteristic points at the circumferential area of the hydraulic B-axis transition disc (3) in three different positions relative to the B-axis rotation center is extracted; taking P B1 as the origin, a position calibration coordinate system is established , the characteristic points P B1 , P B2 and P B3 are converted to the position calibration coordinate system, and the coordinates of P B2 and P B3 in the coordinate system are obtained as and respectively, specifically: S253、In the coordinate system , for the point , the equation of the straight line on which it lies is obtained by numerical calculation method : S253、In the coordinate system , for the point , the equation of the straight line on which it lies is obtained by numerical calculation method : S254、 by the line equation of the perpendicular bisector of the line segment the midpoint and the slope of the perpendicular line , so that the line segment the line equation of the perpendicular bisector of the line segment S255、by the line segment midpoint and the perpendicular slope , so that the line segment the line l2 of the perpendicular bisector: S256、Solve the intersection point of the straight line l1 and the straight line l2 by simultaneous equations (4) and (5) Coordinates: The coordinates of the intersection point of the straight line l1 and the straight line l2 The parameters of the position calibration coordinate system The coordinates of the intersection point of the straight line l1 and the straight line l2 The coordinates of the intersection point of the straight line l1 and the straight line l2 comprehensive formula (1), formula (6) and formula (7), the initial position coordinates of the hydraulic B-axis rotary motion unit are obtained: the initial position calibration of the hydraulic B-axis rotary motion unit is completed; S300, position alignment of the milling shaft rotary motion unit (4), the zero return operation of the hydraulic B-axis rotary motion unit (2) is executed by the program of the micro-structure ultra-precision controlled shape machining system control software, the cumulative rotation angle of the hydraulic B-axis rotary motion unit (2) when the milling shaft is aligned is obtained by the inductive micrometer, the tool (5) is moved to the center of the field of view of the vertical CCD camera (7) based on the CCD vision, the moving distance x1 of the X-axis linear motion unit (11) and the moving distance z1 of the Z-axis linear motion unit (1) are obtained, and the positioning of the milling shaft rotary motion unit (4) is completed; The positioning device comprises an X-axis linear motion unit (11), a Y-axis linear motion unit (10), a Z-axis linear motion unit (1), a hydraulic B-axis rotary motion unit (2), a workpiece C-axis rotary motion unit (9), a milling shaft rotary motion unit (4), a horizontal CCD camera (6), a vertical CCD camera (7) and an inductive micrometer, The X-axis linear motion unit (11) and the Z-axis linear motion unit (1) are arranged in a horizontal plane and perpendicular to each other, the Y-axis linear motion unit (10) is arranged on the X-axis linear motion unit (11), the workpiece C-axis rotary motion unit (9) is arranged on the Y-axis linear motion unit (10), the workpiece C-axis rotary motion unit (9) is used for clamping the workpiece thin-walled spherical shell (8), the hydraulic B-axis rotary motion unit (2) is arranged on the Z-axis linear motion unit (1) through a transition plate, the hydraulic B-axis rotary motion unit (2) is connected with the hydraulic B-axis transition disc (3), the hydraulic B-axis transition disc (3) is arranged concentrically with the hydraulic B-axis rotary motion unit (2), the milling shaft rotary motion unit (4) is arranged on the hydraulic B-axis transition disc (3) through a shaft sleeve, a tool clamping end of a tool (5) of the milling shaft rotary motion unit (4) is used for clamping the tool (5), the horizontal CCD camera (6) is arranged on the hydraulic B-axis transition disc (3) through a micro-displacement platform, the vertical CCD camera (7) is arranged on the Y-axis linear motion unit (10) through a micro-displacement platform, and the electric inductive micrometer is arranged on the hydraulic B-axis transition disc (3).

2. The positioning method according to claim 1, characterized in that, In step S100, specifically comprising: S110, power on the ultra-precision controlled shaping machining system, establish communication between the host computer and the controller, move the X-axis linear motion unit (11), the Y-axis linear motion unit (10) and the Z-axis linear motion unit (1) to the zero interval, and enable the X-axis linear motion unit (11), the Y-axis linear motion unit (10) and the Z-axis linear motion unit (1); S120, by the microstructure ultra-precision controlled shaping machining system control software, execute program zero operation, move the X-axis linear motion unit (11), the Y-axis linear motion unit (10) and the Z-axis linear motion unit (1) to the zero position, and establish the machine tool coordinate system; S130, by the microstructure ultra-precision controlled shaping machining system control software, control the micro-feeding motion of each axis, observe the movement of the linear motion unit in the YOZ plane through the horizontal high-resolution CCD camera, observe the movement of the linear motion unit in the XOZ plane through the vertical CCD camera (7), complete the tool setting operation of the linear motion unit based on the CCD vision, and record the movement distance Δx of the X-axis linear motion unit (11), the movement distance Δy of the Y-axis linear motion unit (10) and the movement distance Δz of the Z-axis linear motion unit (1) by the microstructure ultra-precision controlled shaping machining system control software.

3. The positioning method according to claim 2, characterized in that, In step S130, specifically comprising: S131, when tool setting based on the CCD vision, the contact situation of the X-axis linear motion unit (11) and the Z-axis linear motion unit (1) in the plane parallel to the machine tool YOZ plane is observed through the horizontal CCD camera (6), the linear motion unit is adjusted so that the workpiece C-axis rotary motion unit (9) fixed on the Y-axis linear motion unit (10) and the milling shaft axis are approximately isohypse in the plane parallel to the controlled shaping machining equipment YOZ plane; the linear motion unit is adjusted so that the thin-walled spherical shell workpiece is approximately close to the tool (5); S132, based on CCD vision, the contact condition of the X-axis linear motion unit (11) and the Z-axis linear motion unit (1) in the XOZ plane of the machine tool is observed by the horizontal CCD camera (6), the linear motion unit is adjusted so that the workpiece C-axis rotary motion unit (9) and the milling shaft axis are approximately collinear in the XOZ plane parallel to the machine tool, and the position calibration of the workpiece C-axis rotary motion unit (9) is completed; S133, based on CCD vision, the linear motion unit is controlled to micro-feed by the program, the precise tool setting of the workpiece thin-walled spherical shell (8) and the tool (5) is completed by image observation, and the movement distances Δx, Δy and Δz of the X-axis linear motion unit (11), the Y-axis linear motion unit (10) and the Z-axis linear motion unit (1) are recorded.

4. The positioning method according to claim 3, characterized in that, In step S300, specifically comprising: S310, the hydraulic B-axis rotary motion unit (2) is controlled by the program to perform the zero reset operation, the Z-axis linear motion unit (1) is moved, and the milling shaft axis placed on the hydraulic B-axis rotary motion unit (2) is measured and aligned by the inductive micrometer, so that the milling shaft axis is parallel to the movement direction of the Z-axis linear motion unit, the cumulative rotation angle θ of the hydraulic B-axis rotary motion unit (2) when the milling shaft is aligned is obtained; S320, the linear motion unit is moved by the program, the feature point of the end tool (5) of the milling shaft is observed by the vertical CCD camera (7), so that the ball center of the ball head milling cutter is located in the center of the CCD field of view, the movement distance Δx1 of the X-axis linear motion unit (11) and the movement distance Δz1 of the Z-axis linear motion unit (1) are obtained, and the positioning of the milling shaft rotary motion unit (4) is completed.

5. The positioning method of claim 4, wherein: α＞40°，β＞40°。

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