Additive and subtractive finishing method and system for spherical grinding wheel

Abstract

The invention belongs to the related technical field of grinding wheel precision dressing, and discloses an additive and subtractive dressing method and system for a spherical grinding wheel. The method comprises the following steps: S1, additive finishing: (a) acquiring an image of the current position of a spherical grinding wheel to be finished, extracting the outer contour of the spherical grinding wheel to be finished in the image, calculating a filling volume, and carrying out additive filling according to the filling volume; (b) the spherical grinding wheel to be trimmed swings and rotates, and the step (a) is repeated until the whole outer contour of the spherical grinding wheel to be trimmed is traversed; and S2, subtractive finishing is conducted, images of the surface of the to-be-finished spherical grinding wheel are collected, outer contours in all the images are extracted, an outer circle and an inner circle after all the outer contours are overlapped are fitted, the part between the outer circle and the inner circle serves as a subtractive removal area, and finishing of the to-be-finished spherical grinding wheel is completed after the area is removed. By means of the method, the problems of abrasion and vibration of traditional contact type dressing are solved, material removal in the dressing process is reduced, the dressing frequency of the spherical grinding wheel is increased, and the utilization rate of the spherical grinding wheel is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field related to precision dressing of grinding wheels, and more specifically, relates to an additive and subtractive dressing method and system for a spherical grinding wheel. Background Art

[0002] Grinding is a method of machining the surface of a workpiece using abrasives. It has the advantages of high machining accuracy and good surface quality. Therefore, it is widely used in mechanical manufacturing, aerospace, optical manufacturing and other fields. With the development of technology, more and more spherical and free-form surface machining requirements have emerged. Flat grinding wheels cannot meet their machining needs. Therefore, the use of curved grinding wheels such as spherical grinding wheels is increasing. However, during the machining process, the spherical grinding wheel will lose its contour accuracy due to the blunting and shedding of the abrasive grains. This not only increases the grinding force and the grinding temperature, but also causes the contour error of the spherical grinding wheel to be mapped to the surface of the workpiece due to the loss of contour accuracy, thereby affecting the accuracy of the machined surface. Therefore, it is necessary to regularly dress the grinding wheel to maintain the contour accuracy.

[0003] Most of the existing grinding wheel dressing devices are offline dressing devices, which require the grinding wheel to be removed from the machine tool and installed on a special dressing device for dressing. The repeated disassembly and assembly of the grinding wheel introduces clamping errors, which reduces the dressing accuracy of the grinding wheel. The grinding wheel dressing methods include mechanical dressing, electric spark dressing, additive dressing, etc. The mechanical dressing method uses a diamond pen or a dressing wheel to grind the grinding wheel, which is a contact dressing method. The loss of the dressing tool is extremely large, and the interaction between the dressing tool and the abrasive during the dressing process is likely to reduce the holding force of the binder on the abrasive. Electric spark dressing avoids the contact problem in mechanical dressing, but the efficiency is low and can only be used for conductive grinding wheels. Compared with additive dressing, subtractive dressing requires the removal of a large amount of material, which reduces the number of repeatable dressing times of the grinding wheel and affects the service life of the grinding wheel. The additive dressing method mainly fills the surface defects of the grinding wheel, which can increase the number of dressing times of the grinding wheel and increase the utilization rate of the grinding wheel. However, the additive dressing accuracy is low, and it is difficult to perform fine surface profile control. In summary, the current technical solutions for grinding wheel dressing still have many defects. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a method and system for additive and subtractive dressing of a spherical grinding wheel, which solves the problems of low precision, low efficiency and large dressing amount in the existing spherical grinding wheel dressing process.

[0005] To achieve the above object, according to one aspect of the present invention, a method for adding or subtracting material to a spherical grinding wheel is provided, the method comprising the following steps:

[0006] S1 Additive Finishing

[0007] (a) collecting an image of the current position of the spherical grinding wheel to be dressed, extracting the outer contour of the spherical grinding wheel to be dressed in the image, comparing the extracted outer contour with the ideal outer contour, calculating the concave area of ​​the concave region, calculating the filling volume using the calculated concave area, and performing additive filling according to the filling volume;

[0008] (b) the spherical grinding wheel to be dressed is rotated, and step (a) is repeated until the entire outer contour of the spherical grinding wheel to be dressed is traversed;

[0009] S2 Subtractive finishing

[0010] The outer contour image of the spherical grinding wheel to be dressed is collected, and the spherical grinding wheel to be dressed is swung and rotated until all images of the entire outer contour of the spherical grinding wheel to be dressed are obtained, the outer contour of the spherical grinding wheel to be dressed in all images is extracted and all the extracted outer contours are superimposed, the outer circle and inner circle of all the superimposed outer contours are fitted, and the part between the outer circle and the inner circle is used as the area for subtractive removal. After removing the area, the dressing of the spherical grinding wheel to be dressed is completed.

[0011] Further preferably, the outer contour of the spherical grinding wheel to be dressed in the extracted image is obtained by sequentially adopting grayscale conversion, Gaussian filtering and Canny operator edge detection.

[0012] Further preferably, in step S1, the filling volume is the product of the recessed area and a preset filling factor, and the preset filling factor is set according to the sampling frequency, the rotation speed of the spherical grinding wheel to be dressed, and the image magnification.

[0013] Further preferably, the outer circle and the inner circle of the fitting outer contour are performed according to the following steps:

[0014] For the outer contour in the image acquired after the spherical grinding wheel to be dressed is rotated α degrees relative to the starting position, the outer contour image is rotated -α degrees with the center of the spherical grinding wheel to be dressed as the center, and the outer contour angles of all acquired images are adjusted in this way;

[0015] All the outer contours that have completed angle adjustment are superimposed in an image with the center of the spherical grinding wheel to be dressed as the center, and all the superimposed outer contours are fitted to obtain the outer circle and inner circle of all the outer contours.

[0016] Further preferably, the fitting is performed using a least squares method.

[0017] According to another aspect of the present invention, a system for dressing a spherical grinding wheel according to the above-mentioned additive and subtractive dressing method is provided, the system comprising a visual module, an additive and subtractive module and a control module, wherein:

[0018] The visual module is used to collect images of the spherical grinding wheel to be dressed; the additive and subtractive material module is used to perform additive and subtractive dressing on the spherical grinding wheel to be dressed;

[0019] The control module is connected to the visual module and the additive and subtractive module at the same time, and is used to extract the outer contour of the spherical grinding wheel according to the collected image, compare the outer contour with the ideal contour to calculate the filling volume, and then control the additive and subtractive module to perform additive dressing on the spherical grinding wheel to be dressed according to the filling volume; the control module is also used to fit the outer circle and inner circle of all outer contours, calculate the subtractive removal area, and control the additive and subtractive module to perform subtractive dressing on the spherical grinding wheel to be dressed.

[0020] Further preferably, the system also includes a mobile module, the visual module and the additive and subtractive material module are arranged on the mobile module, the mobile module is connected to the control module, and the control module controls the movement of the mobile module so that the visual module and the additive and subtractive material module move to the spherical grinding wheel to be dressed.

[0021] Further preferably, a rotating base is provided at the front end of the mobile module, and the visual module and the additive and subtractive material module are arranged on the rotating base. The rotating base is provided with a track along the circumferential direction, which serves as the track for the visual module and the additive and subtractive material module to rotate along the circumferential direction. The rotating base is also provided with an axial driving module, which is used to drive the visual module and the additive and subtractive material module to move forward and backward along the radial direction of the rotating base.

[0022] Further preferably, the additive and subtractive material module comprises a laser head and a spray head, the spray head is used for spraying material, and the laser head is used for laser melting the sprayed material or for performing subtractive processing on the surface of the spherical grinding wheel to be dressed.

[0023] According to another aspect of the present invention, there is provided a system for additive and subtractive dressing of a spherical grinding wheel, the system comprising an actuator for executing the above-mentioned method for additive and subtractive dressing of a spherical grinding wheel.

[0024] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0025] 1. The present invention combines the use of additive and subtractive dressing methods to first perform laser additive repair on the surface defects of the spherical grinding wheel and then perform laser subtractive removal, which not only avoids the wear and vibration problems of traditional contact dressing, but also reduces material removal during the dressing process, thereby increasing the number of spherical grinding wheel dressing times and improving the utilization rate, dressing accuracy and efficiency of the spherical grinding wheel.

[0026] 2. The present invention introduces machine vision in the trimming process, detects the contour in real time through machine vision to guide additive trimming, and extracts the minimum edge through contour superposition processing to guide subtractive trimming, which increases the trimming accuracy and improves the trimming efficiency.

[0027] 3. The device of the present invention can be flexibly moved and assembled, so it can be installed in different machine tool stations to dress the grinding wheel. It has strong scene adaptability and versatility. The present invention realizes in-situ dressing of the grinding wheel and avoids clamping errors introduced by repeated disassembly and assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of a method for adding and subtracting material dressing of a spherical grinding wheel constructed according to a preferred embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of collecting an image of a spherical grinding wheel to be dressed constructed according to a preferred embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of an image processing process for additive trimming constructed according to a preferred embodiment of the present invention;

[0031] Figure 4 is a schematic diagram of an image processing flow in subtractive finishing constructed according to a preferred embodiment of the present invention;

[0032] Figure 5 It is a structural schematic diagram of an additive and subtractive dressing system for a spherical grinding wheel constructed according to a preferred embodiment of the present invention;

[0033] Figure 6 It is a structural schematic diagram of an additive and subtractive material module constructed according to a preferred embodiment of the present invention.

[0034] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0035] 1- visual module, 2- additive and subtractive material module 2, 3- mobile module, 4- control module;

[0036] 11-CCD camera, 12-first stepper motor, 13-first ball screw;

[0037] 21-fixed plate, 22-laser transmitter, 23-optical fiber, 24-laser focusing head, 25-storage bin, 26-feeding pipe, 27-spraying head, 28-second stepping motor, 29-second ball screw;

[0038] 31-robot, 32-inner ring of rotating base, 33-outer ring of rotating base, 34-third stepping motor. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] The present invention provides a spherical grinding wheel material addition and subtraction in-situ dressing device based on profile information, such as Figure 5 As shown, it includes a visual module 1, an additive and subtractive material module 2, a mobile module 3, and a control module 4. The control module 4 is connected to the visual module 1 and the additive and subtractive material module 2 at the same time, and is used to extract the outer contour according to the collected image, and compare the outer contour with the ideal contour to calculate the filling volume, and then control the additive and subtractive material module 2 to perform additive dressing on the spherical grinding wheel to be dressed according to the filling volume; the control module 4 is also used to fit the outer circle and inner circle of all outer contours, calculate the subtractive removal area, and control the additive and subtractive material module 2 to perform subtractive dressing on the spherical grinding wheel to be dressed. The visual module 1 and the additive and subtractive material module 2 are arranged on the mobile module 3, and all the mobile modules 3 are connected to the control module 4. The control module 4 controls the mobile module 3 to move so that the visual module 1 and the additive and subtractive material module 2 move to the spherical grinding wheel to be dressed.

[0041] In one embodiment of the present invention, the mobile module includes a robot 31, a rotating base inner ring 32, a rotating base outer ring 33, and a third stepper motor 34. The robot 31 controls the movement of the device and the rotation of the rotating base inner ring 31; the third stepper motor 34 controls the rotation of the rotating base outer ring 33.

[0042] In one embodiment of the present invention, the vision module includes a CCD camera 11, a first stepper motor 12 and a first ball screw 13. The CCD camera 11 is installed on the first ball screw 13. The first stepper motor 12 controls the movement of the first ball screw 13. The first ball screw 13 is installed on the inner ring 32 of the rotating base and can rotate freely and fix the angle.

[0043] In one embodiment of the present invention, Figure 6As shown, the additive and subtractive material module includes a laser focusing head 24, a spray head 27, a fixed plate 21, a second stepper motor 28, a second ball screw 29, a laser emitter 22, and a storage bin 25. The laser focusing head 24 and the spray head 27 are mounted on the second ball screw 29 through the fixed plate 21. The fixed plate 21 can adjust the angle of the laser focusing head 24 and the spray head 27. The second stepper motor 28 controls the movement of the second ball screw 29. The second ball screw 29 is mounted on the outer ring 33 of the rotating base and can rotate freely and fix the angle. The laser emitter 22 is connected to the laser focusing head 24 through the optical fiber 23. The storage bin 25 is connected to the spray head 27 through the feeding pipe 26; the laser emitter 22, the storage bin 25 and the machine tool are linked through the control module 4.

[0044] The steps of the method of adding and subtracting material dressing of spherical grinding wheels are as follows:

[0045] Change the positions of the vision module, the additive and subtractive material module and the grinding wheel. Specifically: in additive dressing, the control module controls the robot end to rotate and adjust the inner ring angle of the rotating base, and controls the third stepper motor to adjust the outer ring angle of the rotating base, so that the angle between the vision module and the additive and subtractive material module is required for processing; control the robot to adjust the position of the rotating base so that the intersection of the vision module camera axis and the additive and subtractive material module laser focusing head axis is located at the vertex of the spherical grinding wheel surface.

[0046] The first stepper motor is controlled to drive the first ball screw to move radially along the rotating base to adjust the focal length of the camera so that the edge of the spherical grinding wheel contour can be clearly identified, and the camera is calibrated. The second stepper motor is controlled to drive the second ball screw to move radially along the rotating base to adjust the distance between the laser focusing head and the spray head and the surface of the spherical grinding wheel, and the angle between the spray head and the laser focusing head is adjusted so that the axes of the laser focusing head and the spray head intersect at the vertex of the grinding wheel surface; in subtractive dressing, the axis of the laser focusing head is adjusted to be tangent to the grinding wheel surface, and the rest of the adjustments are the same as additive dressing.

[0047] The additive dressing method includes the following steps: setting the laser power, spot size, and spray rate in additive dressing. Fixing the position of the camera and the additive and subtractive material module, determining the grinding wheel swing and rotation parameters and dressing range in additive dressing, generating the machine tool movement trajectory according to the dressing parameters, and controlling the spherical grinding wheel movement and the linkage between the machine tool and the visual module and the additive and subtractive material module through the control module. Setting the sampling frequency of the visual module, collecting the spherical grinding wheel contour through the visual module during the movement of the spherical grinding wheel and transmitting it to the computer end of the control module, identifying the contour through grayscale conversion, Gaussian filtering, and Canny operator edge detection, comparing it with the ideal contour, calculating the area s of the concave area formed by the actual contour and the ideal contour envelope, where the area enclosed by the actual fitting contour above the ideal contour is recorded as 0. If the envelope area is greater than the set value, a signal is sent to the additive and subtractive material module to fill the material with a volume of k·s. Where k is adjusted and preset according to the sampling frequency, grinding wheel speed, and visual module magnification.

[0048] The subtractive dressing method includes the following steps: first, turn off the laser, use the visual module to collect the contour of the spherical grinding wheel, and the specific steps are: fix the position of the camera and the additive and subtractive module, determine the grinding wheel swing and rotation parameters and the dressing range in the subtractive dressing, generate the machine tool movement trajectory according to the dressing parameters, control the spherical grinding wheel and each module through the control module, take several photos at different rotation positions under different swing angles of the spherical grinding wheel, and use the same method as in additive processing to extract the edge contour, and record the swing angle α during shooting. i , edge midpoint m i The perpendicular intersection point with the ideal contour d i , d i The center coordinate of the photo is marked as (x di ,y di ), d i The actual coordinates are marked as (x′ di , y′ di ), where i is the photo number. For each local contour image, according to the recorded swing angle α i Rotate and according to the intersection point d i The difference between the position in the photo and the actual position moves the contour image to the actual position. The coordinates of the pixel point in the photo before processing are (x, y), and the coordinates of the pixel point after processing are (x′, y′). The photo is rotated according to the swing angle, and the coordinates of the pixel point after rotation are (x r ,y r ), whose formula is:

[0049]

[0050] Note the intersection point d in the photo at this time i The coordinates are Perform overall translation on the rotated contour image:

[0051]

[0052] If α i If they are the same, the pictures are superimposed. According to this method, the local contours at all different swing angles and rotation angles are stitched in turn, and finally the contour fluctuation of the spherical grinding wheel at the local contour is obtained. The Canny operator is used to extract the inner and outer edges of the total contour change diagram to obtain the maximum and minimum contours of the grinding wheel during one rotation. The maximum and minimum contours are fitted with the least squares circle to obtain the maximum ideal contour and the minimum ideal contour. The laser power and spot size are set in the subtractive dressing, and the step dressing trajectory is generated between the maximum and minimum ideal contours. The control module controls the machine tool and the additive and subtractive module to complete the dressing of the spherical grinding wheel.

[0053] The present invention will be further described below with reference to specific embodiments.

[0054] The present invention provides a spherical grinding wheel material addition and subtraction dressing device and method based on profile information, such as Figure 2 As shown, specifically, taking the dressing of a diamond spherical grinding wheel with a diameter of 3 mm as an example, a method for performing refined in-situ dressing based on contour information extracted by visual detection is described in detail.

[0055] In this embodiment, the position adjustment includes the following steps:

[0056] In additive finishing, the robot is controlled by the control module to adjust the angle of the inner circle of the rotating base, and the third stepper motor is controlled to adjust the angle of the rotating base, so that the angle between the visual module and the additive and subtractive module is 90°, and the angle between the visual module and the horizontal plane is 0°. The robot is controlled to adjust the position of the visual module and the additive and subtractive module so that the intersection of the axis of the camera 11 and the axis of the laser focusing head is located at the vertex of the spherical grinding wheel surface. The camera magnification is 200 times. The first stepper motor is controlled to drive the first ball screw to rotate, and the camera focal length is adjusted so that the edge of the spherical grinding wheel contour can be clearly identified. The second stepper motor is controlled to drive the second ball screw to rotate, and the focus of the laser focusing head is adjusted to fall on the surface of the spherical grinding wheel. The angle between the spray head and the laser focusing head is adjusted so that the axes of the laser focusing head and the spray head intersect at the vertex of the grinding wheel surface, and the position of the ideal contour of the visual module and the spherical grinding wheel is calibrated. In subtractive finishing, the axis of the laser focusing head is adjusted to be tangent to the surface of the grinding wheel, and the rest of the adjustments are the same as additive finishing. The mobile robot has a repeatability accuracy of less than 0.05mm, and the ball screw is C0 grade with an error of less than 5μm.

[0057] S1 additive finishing, including the following steps:

[0058] Set the laser power in additive finishing to 30w, the spot diameter to 0.05mm, and the injection rate to 0.5mm 3 / s, the grinding wheel swing line speed is 0.1mm / s, and the rotation speed is 30rpm. The camera and the additive and subtractive material module positions are fixed, and the machine tool movement trajectory is generated according to the dressing parameters. The spherical grinding wheel is controlled by the control module to link with each module, such as Figure 2 The sampling frequency of the visual module is set to 100 Hz. During the movement of the spherical grinding wheel, the visual module collects the contour of the spherical grinding wheel and transmits it to the computer. The contour is identified through grayscale conversion, Gaussian filtering, and Canny operator edge detection, and compared with the ideal contour, as shown in Figure 1. Figure 3 As shown, the area s of the concave area formed by the envelope of the actual contour and the ideal contour is calculated, where the area enclosed by the actual fitting contour above the ideal contour is recorded as 0. Preset k = 0.3, if the calculated envelope area is greater than 0.04mm 2 , a signal is sent to the additive and subtractive material module to fill the volume k·s of material.

[0059] S2 subtractive finishing includes the following steps:

[0060] First, turn off the laser and use the visual module to collect the contour of the spherical grinding wheel. The specific steps are as follows: fix the position of the camera and the additive and subtractive material module, set the grinding wheel swing linear speed to 0.1mm / s and the rotation speed to 200rpm, generate the machine tool movement trajectory according to the dressing parameters, and control the spherical grinding wheel and each module through the control module. Figure 4 As shown in the figure, 100 local contour images at different rotation positions are collected at a frequency of 100 Hz every 5° at different swing angles of the spherical grinding wheel, and the edge contour is extracted using the same method as in additive trimming, while the swing angle α is recorded during shooting. i , edge midpoint m i The perpendicular intersection point with the ideal contour d i , d i The center coordinate of the photo is marked as (x di ,y di ), d i The actual coordinates are marked as (x′ di , y′ di ), where i is the photo number. For each local contour image, according to the recorded swing angle α i Rotate and according to the intersection point d i The difference between the position in the photo and the actual position moves the contour image to the actual position. The coordinates of the pixel point in the photo before processing are (x, y), and the coordinates of the pixel point after processing are (x′, y′). The photo is rotated according to the swing angle, and the coordinates of the pixel point after rotation are (x r ,y r ), whose formula is:

[0061]

[0062] Note the intersection point d in the photo at this time i The coordinates are Perform overall translation on the rotated contour image:

[0063]

[0064] If α i If they are the same, the pictures are superimposed. According to this method, the local contours at all different swing angles and rotation angles are stitched in turn, and finally the contour fluctuation of the spherical grinding wheel at the local contour is obtained. The Canny operator is used to extract the inner and outer edges of the total contour change diagram to obtain the maximum and minimum contours of the grinding wheel during one rotation. The maximum and minimum contours are fitted with the least squares circle to obtain the maximum ideal contour and the minimum ideal contour. The laser power is set to 50w and the spot diameter is 0.02mm in the subtractive dressing process. A step dressing trajectory is generated between the maximum and minimum ideal contours. The control module is used to control the machine tool and the additive and subtractive module to complete the dressing of the spherical grinding wheel.

[0065] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for adding or subtracting material to a spherical grinding wheel, characterized in that: The method comprises the following steps: S1 Additive Finishing (a) collecting an image of the current position of the spherical grinding wheel to be dressed, extracting the outer contour of the spherical grinding wheel to be dressed in the image, comparing the extracted outer contour with the ideal outer contour, calculating the concave area of ​​the concave region, calculating the filling volume using the calculated concave area, and performing additive filling according to the filling volume; (b) the spherical grinding wheel to be dressed is swung and rotated, and step (a) is repeated until the entire outer contour of the spherical grinding wheel to be dressed is traversed; S2 Subtractive finishing The outer contour image of the spherical grinding wheel to be dressed is collected, and the spherical grinding wheel to be dressed is swung and rotated until all images of the entire outer contour of the spherical grinding wheel to be dressed are obtained, the outer contour of the spherical grinding wheel to be dressed in all images is extracted and all the extracted outer contours are superimposed, the outer circle and inner circle of all the superimposed outer contours are fitted, and the part between the outer circle and the inner circle is used as the area for subtractive removal. After removing the area, the dressing of the spherical grinding wheel to be dressed is completed.

2. A method for adding or subtracting material to dress a spherical grinding wheel as claimed in claim 1, characterized in that: The outer contour of the spherical grinding wheel to be dressed in the extracted image is obtained by grayscale conversion, Gaussian filtering and Canny operator edge detection in sequence.

3. A method for adding or subtracting material to dress a spherical grinding wheel as claimed in claim 1 or 2, characterized in that: In step S1, the filling volume is the product of the depression area and a preset filling factor, and the preset filling factor is set according to the sampling frequency, the rotation speed of the spherical grinding wheel to be dressed, and the image magnification.

4. A method for adding or subtracting material to dress a spherical grinding wheel as claimed in claim 1 or 2, characterized in that: The outer circle and inner circle of the fitting outer contour are performed according to the following steps: For the outer contour in the image captured after the spherical grinding wheel to be dressed is rotated α degrees relative to the horizontal position, the outer contour is rotated -α degrees with the center of the spherical grinding wheel to be dressed as the center, and the outer contour angle of all captured images is adjusted in this way; All the outer contours that have completed angle adjustment are superimposed in an image with the center of the spherical grinding wheel to be dressed as the center, and all the superimposed outer contours are fitted to obtain the outer circle and inner circle of all the outer contours.

5. A method for adding or subtracting material to dress a spherical grinding wheel as claimed in claim 4, characterized in that: The fitting is performed using the least square method.

6. A system for dressing a spherical grinding wheel according to the additive and subtractive dressing method of any one of claims 1 to 5, characterized in that: The system comprises a vision module (1), an additive and subtractive material module (2) and a control module (4), wherein: The visual module (1) is used to collect images of the spherical grinding wheel to be dressed; the additive and subtractive material module (2) is used to perform additive and subtractive dressing on the spherical grinding wheel to be dressed; The control module (4) is connected to the visual module (1) and the additive and subtractive material module (2) at the same time, and is used to extract the outer contour according to the collected image, compare the outer contour with the ideal contour to calculate the filling volume, and then control the additive and subtractive material module (2) to perform additive manufacturing on the spherical grinding wheel to be dressed according to the filling volume; the control module (4) is also used to fit the outer circle and inner circle of all outer contours, calculate the subtractive removal area, and control the additive and subtractive material module (2) to perform subtractive manufacturing on the spherical grinding wheel to be dressed.

7. The system according to claim 6, characterized in that The system further comprises a moving module (3), the visual module (1) and the additive and subtractive material module (2) being arranged on the moving module (3), the moving module (3) being connected to a control module (4), and the control module (4) controlling the movement of the moving module (3) so that the visual module (1) and the additive and subtractive material module (2) are moved to a position where the spherical grinding wheel is to be trimmed.

8. The system according to claim 6 or 7, characterized in that A rotating base is arranged at the front end of the mobile module (3), the visual module (1) and the additive and subtractive material module (2) are arranged on the rotating base, two tracks along the circumferential direction are arranged on the rotating base, the two tracks respectively serve as tracks for the visual module (1) and the additive and subtractive material module (2) to rotate along the circumferential direction, and an axial driving module is also arranged on the rotating base, the axial driving module is respectively used to drive the visual module (1) and the additive and subtractive material module (2) to move forward and backward along the radial direction of the rotating base.

9. The system according to claim 8, characterized in that The additive and subtractive material module (2) comprises a laser head and a spray head (27), wherein the spray head (27) is used for spraying material, and the laser head is used for laser melting the sprayed material or for performing subtractive processing on the surface of a spherical grinding wheel to be dressed.

10. A spherical grinding wheel additive and subtractive dressing system, characterized in that: The system comprises an actuator, which is used to execute the additive and subtractive dressing method of a spherical grinding wheel as described in any one of claims 1 to 5.

Images