A double-disc cooperative optical element processing method

Abstract

The present application relates to the technical field of optical element processing, and particularly relates to a double-grinding-disc cooperative optical element processing method, comprising the following steps: determining surface shape error data; selecting a first grinding disc and a second grinding disc, the size of the first grinding disc being larger than the size of the second grinding disc, obtaining a removal function of the first grinding disc and a removal function of the second grinding disc; planning a second circular ring processing track and a first circular ring processing track; obtaining a first target processing dwell time of each dwell point in the first circular ring processing track, and obtaining a second target processing dwell time of each dwell point in the second circular ring processing track; determining processing parameters based on the first target processing dwell time, the second target processing dwell time, the second circular ring processing track and the first circular ring processing track; and processing a first grinding disc processing area by using the first grinding disc while processing a second grinding disc processing area by using the second grinding disc. The present application is at least beneficial to improving processing efficiency and processing quality.

Description

Technical Field

[0001] This invention belongs to the field of optical element processing technology, and particularly relates to a method for processing optical elements using a dual-grinding-disc method. Background Technology

[0002] With the development of modern optical technology, high-precision optical mirrors play an important role in several cutting-edge fields. To ensure the processing efficiency and final performance of optical systems, high requirements are also placed on the overall aperture error of the mirror. In the 1970s, computer-controlled optical surface forming technology was proposed and gradually developed. This technology uses CNC grinding and polishing tools to quantitatively grind or polish the mirror surface based on quantitative surface shape data, which greatly improves the efficiency of mirror processing.

[0003] Computer-controlled optical surface forming technology based on small grinding heads is often used in lens grinding and polishing. For complex curved surface processing such as aspherical mirrors, small grinding heads can better fit the optical surface due to their small-sized grinding discs. However, when the grinding disc reaches the edge of the workpiece, part of the grinding disc becomes suspended, which leads to changes in the grinding disc pressure distribution and makes the removal function unstable. When there is too much suspension, even a "disk flipping" phenomenon may occur. Therefore, a margin is left during trajectory planning before processing. When processing the edge, the trajectory of the center point of the grinding disc always maintains a certain distance from the edge. However, when the target removal amount at the edge is abnormal (too high or too low), the grinding disc stay time at the edge trajectory is too long, resulting in an increase in the removal amount near the edge and the formation of pits. The position and size of the pits are mainly related to the size of the grinding disc and introduce boundary ringing, which reduces the surface accuracy.

[0004] Existing technologies mainly measure and compensate for the edge effect after it occurs. Specifically, the mirror surface is first polished at full diameter, and then the edge error is corrected separately using a small-sized polishing tool or other processes. This requires continuous adjustment of processing parameters and multiple rounds of processing to finally achieve convergence of the edge error. This processing method is time-consuming and affects the convergence speed and processing efficiency of the surface shape error. Summary of the Invention

[0005] In view of this, the present invention aims to provide an optical element processing technology that at least helps to improve processing efficiency and processing quality.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows: This invention provides a dual-grinding-disc collaborative optical element processing method, comprising: Step 1: determining surface shape error data; Step 2: selecting a first grinding disc and a second grinding disc, wherein the size of the first grinding disc is larger than the size of the second grinding disc, and obtaining the removal function of the first grinding disc and the removal function of the second grinding disc; Step 3: determining the processing area of ​​the first grinding disc and the processing area of ​​the second grinding disc, planning a second circular processing trajectory based on the processing area of ​​the second grinding disc, and planning a first circular processing trajectory based on the processing area of ​​the first grinding disc; Step 4: obtaining the first target processing dwell time of each dwell point in the first circular processing trajectory and the second target processing dwell time of each dwell point in the second circular processing trajectory based on the removal function of the first grinding disc, the removal function of the second grinding disc, and the surface shape error data; Step 5: determining processing parameters based on the first target processing dwell time, the second target processing dwell time, the second circular processing trajectory, and the first circular processing trajectory; Step 6: controlling the rotation of the workpiece, controlling the rotation of the first grinding disc, and controlling the rotation of the second grinding disc based on the processing parameters, so that the first grinding disc processes the processing area of ​​the first grinding disc while the second grinding disc processes the processing area of ​​the second grinding disc.

[0007] Furthermore, in step 1, determining the surface shape error data includes: determining the target surface shape data of the target lens, obtaining the unprocessed surface shape data of the lens to be processed, and determining the surface shape error data based on the unprocessed surface shape data and the target surface shape data.

[0008] Further, in step 2, obtaining the removal function of the first grinding disc includes: using the first grinding disc to perform single-point polishing on the experimental piece with the same material as the lens to be processed, forming a first polishing spot, the rotation speed of the first grinding disc is a first initial rotation speed, the pressure of the first grinding disc is a first initial pressure, measuring the three-dimensional morphology of the first polishing spot to obtain the depth distribution of the first polishing spot, and dividing the depth distribution of the first polishing spot by the corresponding polishing time to obtain the removal function of the first grinding disc under the first initial rotation speed and the first initial pressure; obtaining the removal function of the second grinding disc includes: using the second grinding disc to perform single-point polishing on the experimental piece with the same material as the lens to be processed, forming a second polishing spot, the rotation speed of the second grinding disc is a second initial rotation speed, the pressure of the second grinding disc is a second initial pressure, measuring the three-dimensional morphology of the second polishing spot to obtain the depth distribution of the second polishing spot, and dividing the depth distribution of the second polishing spot by the corresponding polishing time to obtain the removal function of the second grinding disc under the second initial rotation speed and the second initial pressure.

[0009] Furthermore, in step 3, determining the first and second grinding disc processing areas includes: dividing the processing area of ​​the lens to be processed into a central processing area and a collaborative processing area. The collaborative processing area surrounds the central processing area. The central processing area is the area processed by the first grinding disc using a spiral trajectory. The collaborative processing area includes a first annular processing area, a second annular processing area, and a third annular processing area. The second annular processing area surrounds the first annular processing area, and the third annular processing area surrounds the second annular processing area. The first annular processing area is the area processed by the first grinding disc using a circular trajectory. The second annular processing area is the area jointly processed by the first and second grinding discs using a circular trajectory. The third annular processing area is the area processed by the second grinding disc using a circular trajectory. The first and second annular processing areas constitute the first grinding disc processing area, and the second and third annular processing areas constitute the second grinding disc processing area.

[0010] Furthermore, in step 3, the width of the processing area of ​​the second grinding disc is not less than the sum of the diameter of the first grinding disc and the safe distance from the center of the first grinding disc to the edge of the mirror.

[0011] Furthermore, in step 6, the workpiece stage drives the lens to be processed to rotate and the first grinding disc to rotate, so that the first grinding disc completes the processing of the first grinding disc processing area along the first circular processing trajectory. The workpiece stage rotates and the second grinding disc rotates, so that the second grinding disc completes the processing of the second grinding disc processing area along the second circular processing trajectory. While the second grinding disc is processing along any circle of the second circular processing trajectory, the first grinding disc is processing along any circle of the first circular processing trajectory, and the relative positions of the first grinding disc and the second grinding disc remain unchanged. When the second grinding disc completes the processing of the second grinding disc processing area, a robotic arm connected to the second grinding disc is used to take the second grinding disc out of the processing area, and the first grinding disc continues to process until the first grinding disc completes the processing of the first grinding disc processing area. Then, the workpiece stage stops rotating, and a robotic arm connected to the first grinding disc drives the first grinding disc to complete the processing of the central processing area along a spiral trajectory.

[0012] Furthermore, in step 4, a material convolution removal model is used to obtain the first target processing dwell time and the second target processing dwell time based on the removal functions of the first grinding disc, the second grinding disc, and the surface error data; the formula of the material convolution removal model is as follows: ;in, This represents a two-dimensional convolution operation. Represents surface shape error data. This represents the removal function of the first grinding disc. Indicates the dwell time for the first target processing. This represents the removal function for the second grinding disc. This indicates the dwell time for the second target processing.

[0013] Furthermore, step 3 also includes: calculating the normal vector of the first mirror dwell point corresponding to the first ring machining trajectory and the normal vector of the second mirror dwell point corresponding to the second ring machining trajectory; The calculation of the normal vector of the first mirror dwell point includes: the machining trajectory of the first annulus is , This represents the three-dimensional coordinates of the dwell point on the machining trajectory of the first ring. , , Represents the station number, This represents the total number of dwell points on the processing trajectory of the first circular ring. The representative serial number is outposts x Axis coordinates The representative serial number is outposts y Axis coordinates The representative serial number is outposts z Axial coordinates, three-dimensional coordinates are The normal vector of the first mirror dwell point of the dwell point ,in, Indicates the normal vector of the first mirror dwell point in x Components on the axis, Indicates the normal vector of the first mirror dwell point in y Components on the axis, Indicates the normal vector of the first mirror dwell point in z Components on the axis, Indicates the corresponding station location xy Coordinates on a plane Represents the target surface shape function pair x The first-order partial derivative, Represents the target surface shape function pair y The first partial derivative of the first grinding disc means that when the first grinding disc is processing at the corresponding dwell point, the axis of the first grinding disc coincides with the normal vector of the first mirror dwell point at the corresponding dwell point. The calculation of the normal vector of the second mirror dwell point includes: the machining trajectory of the second annulus is , This represents the three-dimensional coordinates of the dwell point on the machining trajectory of the second ring. , , Represents the station number, This represents the total number of dwell points on the machining trajectory of the second ring. The representative serial number is outposts x Axis coordinates The representative serial number is outposts y Axis coordinates The representative serial number is outposts z Axial coordinates, three-dimensional coordinates are The normal vector of the second mirror dwell point of the dwell point ,in, Indicates the normal vector of the second mirror dwell point in x Components on the axis, Indicates the normal vector of the second mirror dwell point in y Components on the axis, Indicates the normal vector of the second mirror dwell point in z Components on the axis, Indicates the corresponding station location xy Coordinates on a plane This represents the target surface shape function at the corresponding dwell point. x The first-order partial derivative, This represents the target surface shape function at the corresponding dwell point. y The first partial derivative of the second grinding wheel means that when the second grinding wheel is processing at the corresponding dwell point, the axis of the second grinding wheel coincides with the normal vector of the corresponding dwell point. Step 5 also includes: determining the machining parameters based on the first target machining dwell time, the second target machining dwell time, the second circular machining trajectory, the first circular machining trajectory, the normal vector of the first mirror dwell point, and the normal vector of the second mirror dwell point.

[0014] Furthermore, in step 5, determining the processing parameters includes: Step 51: Place the item with serial number... The first target processing stay time at the station This is converted into the target total number of revolutions of the first grinding disc at that dwell point. , with the serial number The second target processing stay time at the station This is converted into the target total number of revolutions of the second grinding disc at that dwell point. , ; ,in, This indicates the initial rotational speed of the first grinding disc. This indicates the initial rotational speed of the second grinding disc; Step 52: Set the rotational angular velocity of the workpiece stage. angular velocity of rotation Within the safe rotational speed range; Get the serial number as The first actual processing stay time at the station And obtain the serial number as The second actual processing stay time at the station ; ; ; in, This represents the distance between adjacent dwell points on the machining trajectory of the first ring. This indicates the distance between adjacent dwell points on the machining trajectory of the second ring; Step 53: Based on the first actual processing dwell time Second, actual processing dwell time The total number of rotations of the first grinding disc at the corresponding dwell point. And the target total number of rotations at the corresponding dwell point of the second grinding disc. Obtain the first grinding disc at the sequence number. Actual rotational speed at the dwell point And obtain the second grinding disc at serial number Actual rotational speed at the dwell point The total number of revolutions of the same grinding disc at different dwell points remains constant; ; ; Step 54: Determine whether the actual rotational speed corresponding to each dwell point is within the preset safe range. If the actual rotational speed of some dwell points exceeds the preset safe range, return to step 52 and adjust the rotational angular velocity of the workpiece stage. The iteration continues until the actual rotational speed at each dwell point is within the preset safety range, at which point the iteration stops and the final actual rotational speed is obtained. If the actual rotational speed of a certain revolution on the circular machining trajectory is higher than the preset safety range, the rotational speed of that revolution is adjusted to be within the preset safety range. And repeat the processing along the trajectory. Next, the final actual rotational speed, the machining trajectory of the first ring, the machining trajectory of the second ring, and the rotational angular velocity. As processing parameters.

[0015] Furthermore, in step 6, the first grinding disc is controlled to switch radial circular trajectories, the second grinding disc is controlled to switch radial circular trajectories, the axial orientation of the first grinding disc is controlled, and the axial orientation of the second grinding disc is controlled based on the processing parameters.

[0016] Compared with existing technologies, this invention achieves the following beneficial effects: This invention provides a dual-grinding-disc collaborative optical element processing method, effectively suppressing edge effects. Specifically, a large-size first grinding disc and a small-size second grinding disc are used to collaboratively process the mirror surface. The large-size first grinding disc processes the central region of the mirror surface, while the small-size second grinding disc processes the lens edge. This ensures that the large-size first grinding disc does not exhibit any suspended phenomena, thereby maintaining a stable removal function and guaranteeing the accuracy of the dwell time calculation for the first grinding disc processing the central region of the lens. The small-size second grinding disc can reduce the pit size and suppress the introduction of boundary ringing. The removal functions of both grinding discs are simultaneously calculated... The dwell time of the two grinding discs is determined and their speeds are matched. By coordinating the rotation of the workpiece table, the radial feed of the robotic arm, and the rotation of the grinding discs, the two grinding discs can simultaneously process the collaborative processing area. The larger first grinding disc is responsible for large-area active removal, while the smaller second grinding disc is responsible for precision trimming. This helps to improve processing efficiency and quality. When the two grinding discs process the collaborative processing area at the same time, the movement of the grinding discs along the circular trajectory is achieved by the rotation of the workpiece table. The grinding discs only rotate and switch trajectories radially after completing one revolution of processing. Therefore, a simpler trajectory planning method is used to avoid collisions between the two grinding discs, thereby reducing the difficulty of anti-collision trajectory planning. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A simulation diagram of the initial surface shape error distribution of the lens to be processed as described in the embodiment of the present invention; Figure 2 This is a simulation diagram of the surface shape error distribution of a lens obtained after simulation processing using the traditional single-grinding head method; Figure 3 A schematic diagram of a processing trajectory as described in an embodiment of the present invention; Figure 4 This is a simulation diagram of the lens surface shape error distribution obtained after simulation processing using the dual-grinding-disc collaborative optical element processing method described in the embodiments of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] This invention provides a dual-grinding-disc collaborative optical element processing method, comprising: Step 1: determining surface shape error data; Step 2: selecting a first grinding disc and a second grinding disc, wherein the size of the first grinding disc is larger than the size of the second grinding disc, and obtaining the removal function of the first grinding disc and the removal function of the second grinding disc; Step 3: determining the processing area of ​​the first grinding disc and the processing area of ​​the second grinding disc, planning a second circular processing trajectory based on the processing area of ​​the second grinding disc, and planning a first circular processing trajectory based on the processing area of ​​the first grinding disc; Step 4: obtaining the first target processing dwell time of each dwell point in the first circular processing trajectory and the second target processing dwell time of each dwell point in the second circular processing trajectory based on the removal function of the first grinding disc, the removal function of the second grinding disc, and the surface shape error data; Step 5: determining processing parameters based on the first target processing dwell time, the second target processing dwell time, the second circular processing trajectory, and the first circular processing trajectory; Step 6: controlling the rotation of the workpiece, controlling the rotation of the first grinding disc, and controlling the rotation of the second grinding disc based on the processing parameters, so that the first grinding disc processes the processing area of ​​the first grinding disc while the second grinding disc processes the processing area of ​​the second grinding disc. The workpiece is the unfinished lens, and the processing trajectory is the trajectory of the center of the corresponding grinding disc.

[0024] In some embodiments, the ratio of the size of the first grinding disc to the size of the second grinding disc is greater than or equal to 2, where the size of the first grinding disc refers to the diameter of the first grinding disc and the size of the second grinding disc refers to the diameter of the second grinding disc.

[0025] Furthermore, in step 1, determining the surface shape error data includes: determining the target surface shape data of the target lens, acquiring the unprocessed surface shape data of the unprocessed workpiece (lens to be processed), and determining the surface shape error data based on the unprocessed surface shape data and the target surface shape data. The target surface shape data is the discrete point target data obtained by discretizing the target surface shape function of the target lens. , Representing the i discrete points z Target height on axis Representing the i discrete points x Axis coordinates Representing the i discrete points y Axis coordinates i Represents the discrete point index. Unprocessed surface data refers to the discretized surface data of the unprocessed workpiece. , represent i Measured three-dimensional coordinates of a discrete point ,in, Representing the i discrete points z Actual height of the shaft The total number of discrete points; the surface shape error data is the discretized surface shape residual data. , Representing the i Processing vectors for discrete points ,in, , For the first on the lens to be processed i discrete points The difference in elevation relative to the target height, where, and One-to-one correspondence, and One-to-one correspondence, and One-to-one correspondence, , as well as They are corresponding.

[0026] In some embodiments, discrete surface shape data of the lens to be processed can be obtained using measuring devices such as an interferometer. .

[0027] In some embodiments, in step 2, a suitable first grinding disc and a second grinding disc can be selected according to the size and curvature of the lens to ensure that the size, radius of curvature, or abrasive type of the first grinding disc matches the current processing requirements of the lens.

[0028] Further, in step 2, obtaining the removal function of the first grinding disc includes: using the first grinding disc to perform single-point polishing on the experimental piece of the same material as the lens to be processed, forming a first polishing spot. The rotation speed of the first grinding disc is a first initial rotation speed, and the pressure of the first grinding disc is a first initial pressure. A profilometer or interferometer can be used to measure the three-dimensional morphology of the first polishing spot to obtain the depth distribution of the first polishing spot. The depth distribution of the first polishing spot is divided by the corresponding polishing time to obtain the removal function of the first grinding disc under the first initial rotation speed and the first initial pressure. Obtaining the removal function of the second grinding disc includes: using the second grinding disc to perform single-point polishing on the experimental piece of the same material as the lens to be processed, forming a second polishing spot. The rotation speed of the second grinding disc is a second initial rotation speed, and the pressure of the second grinding disc is a second initial pressure. A profilometer or interferometer can be used to measure the three-dimensional morphology of the second polishing spot to obtain the depth distribution of the second polishing spot. The depth distribution of the second polishing spot is divided by the corresponding polishing time to obtain the removal function of the second grinding disc under the second initial rotation speed and the second initial pressure.

[0029] Furthermore, in step 3, determining the first and second grinding disc processing areas includes: dividing the processing area of ​​the lens to be processed into a central processing area and a collaborative processing area. The collaborative processing area surrounds the central processing area. The central processing area is the area processed by the first grinding disc using a spiral trajectory. The collaborative processing area includes a first annular processing area, a second annular processing area, and a third annular processing area. The second annular processing area surrounds the first annular processing area, and the third annular processing area surrounds the second annular processing area. The first annular processing area is the area processed by the first grinding disc using a circular trajectory. The second annular processing area is the area jointly processed by the first and second grinding discs using circular trajectories. The third annular processing area is the area processed by the second grinding disc using a circular trajectory. The first and second annular processing areas constitute the first grinding disc processing area, and the second and third annular processing areas constitute the second grinding disc processing area. In other words, the first and second grinding disc processing areas partially overlap. This design helps to suppress the seam effect caused by the abrupt change in the removal function at the junction.

[0030] The circular trajectory, combined with the rotation of the workpiece stage, can effectively achieve the collaborative processing of the first and second grinding discs. Therefore, for the collaborative processing area, a circular trajectory is used. When the central processing area is close to the center of the lens and the processing point is close to the center, a large rotational speed of the workpiece stage is required to ensure that the relative travel speed between the first grinding disc and the lens meets the requirements. However, a large rotational speed of the workpiece stage will cause deformation of the lens, resulting in a decrease in processing accuracy. Therefore, this invention uses a spiral trajectory for processing in the central processing area close to the center. When using a spiral trajectory, the workpiece stage remains stationary, and the robotic arm controls the first grinding disc to step forward to complete the spiral trajectory processing.

[0031] Furthermore, in step 3, the width of the processing area of ​​the second grinding disc is not less than the sum of the diameter of the first grinding disc and the minimum safe distance from the center of the first grinding disc to the edge of the mirror. The width of the processing area of ​​the second grinding disc needs to be set according to the selected size of the first grinding disc and the minimum safe distance from the center of the first grinding disc to the edge of the mirror. A width of the processing area of ​​the second grinding disc greater than the minimum safe distance from the center of the first grinding disc to the edge of the mirror helps to ensure that the first grinding disc makes complete contact with the lens, preventing the first grinding disc from being suspended, and thus helping to ensure the stability of the removal function of the first grinding disc.

[0032] Furthermore, in step 6, the workpiece stage drives the lens to be processed to rotate and the first grinding disc to rotate, so that the first grinding disc completes the processing of the first grinding disc processing area along the first circular processing trajectory. The workpiece stage rotates and the second grinding disc rotates, so that the second grinding disc completes the processing of the second grinding disc processing area along the second circular processing trajectory. While the second grinding disc is processing along any one circle of the second circular processing trajectory, the first grinding disc is processing along one circle of the first circular processing trajectory, and the relative positions of the first grinding disc and the second grinding disc remain unchanged. In some embodiments, after the second grinding disc completes the processing of the second grinding disc processing area, a robotic arm connected to the second grinding disc is used to take the second grinding disc out of the processing area, and the first grinding disc continues to process until the first grinding disc completes the processing of the first grinding disc processing area. Then, the workpiece stage stops rotating, and a robotic arm connected to the first grinding disc drives the first grinding disc to complete the processing of the central processing area along a spiral trajectory.

[0033] Furthermore, in step 4, a material convolution removal model is used to obtain the first target processing dwell time and the second target processing dwell time based on the removal functions of the first grinding disc, the second grinding disc, and the surface error data; the formula of the material convolution removal model is as follows: ;in, This represents a two-dimensional convolution operation. Represents surface shape error data, when for hour, , This represents the removal function of the first grinding disc. Indicates the dwell time for the first target processing. This represents the removal function for the second grinding disc. This indicates the dwell time for the second target processing.

[0034] Furthermore, step 3 also includes: calculating the normal vector of the first mirror dwell point corresponding to the first ring machining trajectory and the normal vector of the second mirror dwell point corresponding to the second ring machining trajectory; calculating the normal vector of the first mirror dwell point includes: the first ring machining trajectory is... , This represents the three-dimensional coordinates of the dwell point on the machining trajectory of the first ring. , , Represents the station number, This represents the total number of dwell points on the processing trajectory of the first circular ring. The representative serial number is outposts x Axis coordinates The representative serial number is outposts y Axis coordinates The representative serial number is outposts z Axial coordinates, three-dimensional coordinates are The normal vector of the first mirror dwell point of the dwell point ,in, Indicates the normal vector of the first mirror dwell point in x Components on the axis, Indicates the normal vector of the first mirror dwell point in y Components on the axis, Indicates the normal vector of the first mirror dwell point in z Components on the axis, Indicates the corresponding station location xy Coordinates on a plane Represents the target surface shape function pair x The first-order partial derivative, Represents the target surface shape function pair y The first partial derivative of the first grinding disc is such that when the first grinding disc is processed at the corresponding dwell point, the axis of the first grinding disc basically coincides with the normal vector of the first mirror dwell point at the corresponding dwell point, so as to ensure a good contact state and a stable removal function.

[0035] The calculation of the normal vector of the second mirror dwell point includes: the machining trajectory of the second annulus is , This represents the three-dimensional coordinates of the dwell point on the machining trajectory of the second ring. , , Represents the station number, This represents the total number of dwell points on the machining trajectory of the second ring. The representative serial number is outposts x Axis coordinates The representative serial number is outposts y Axis coordinates The representative serial number is outposts z Axial coordinates, three-dimensional coordinates are The normal vector of the second mirror dwell point of the dwell point ,in, Indicates the normal vector of the second mirror dwell point in x Components on the axis, Indicates the normal vector of the second mirror dwell point in y Components on the axis, Indicates the normal vector of the second mirror dwell point in z Components on the axis, Indicates the corresponding station location xy Coordinates on a plane This represents the target surface shape function at the corresponding dwell point.x The first-order partial derivative, This represents the target surface shape function at the corresponding dwell point. y The first-order partial derivative of the second grinding disc means that when the second grinding disc is processing at the corresponding dwell point, the axis of the second grinding disc basically coincides with the normal vector of the corresponding dwell point, so as to ensure a good contact state and a stable removal function.

[0036] Step 5 also includes: determining the machining parameters based on the first target machining dwell time, the second target machining dwell time, the second circular machining trajectory, the first circular machining trajectory, the normal vector of the first mirror dwell point, and the normal vector of the second mirror dwell point.

[0037] Furthermore, in step 5, determining the processing parameters includes: Step 51: Place the item with serial number... The first target processing stay time at the station This is converted into the target total number of revolutions of the first grinding disc at that dwell point. , with the serial number The second target processing stay time at the station This is converted into the target total number of revolutions of the second grinding disc at that dwell point. , ; ,in, This indicates the initial rotational speed of the first grinding disc. This indicates the initial rotational speed of the second grinding disc; Step 52: Set the rotational angular velocity of the workpiece stage. angular velocity of rotation Within the safe rotational speed range; Get the serial number as The first actual processing stay time at the station And obtain the serial number as The second actual processing stay time at the station , ; ; in, This represents the distance between adjacent dwell points on the machining trajectory of the first ring. This indicates the distance between adjacent dwell points on the machining trajectory of the second ring; Step 53: Based on the first actual processing dwell time Second, actual processing dwell time The total number of rotations of the first grinding disc at the corresponding dwell point. And the target total number of rotations at the corresponding dwell point of the second grinding disc. Obtain the first grinding disc at the sequence number. Actual rotational speed at the dwell point And obtain the second grinding disc at serial number Actual rotational speed at the dwell point The grinding wheel speed is matched according to the different target number of machining revolutions at corresponding points of the two grinding wheels to ensure that the corresponding grinding wheel completes the target number of machining revolutions at the corresponding point within the actual processing time. ; ; Step 54: Determine whether the actual rotational speed corresponding to each dwell point is within the preset safe range. If the actual rotational speed of some dwell points exceeds the preset safe range, return to step 52 and adjust the rotational angular velocity of the workpiece stage. The iteration continues until the actual rotational speed at each dwell point is within the preset safety range, at which point the iteration stops and the final actual rotational speed is obtained. If the actual rotational speed at each dwell point on a certain ring of the circular machining trajectory is higher than the preset safety range, the rotational speed of that ring is adjusted to be within the preset safety range. And repeat the processing along the trajectory. Next, among them It is a positive integer value. The settings need to be determined based on the specific rotational speed of the dwell point on the ring, including the final actual rotational speed, the machining trajectory of the first ring, the machining trajectory of the second ring, and the rotational angular velocity. As processing parameters.

[0038] Step 5 essentially involves adjusting machining parameters for speed matching based on the first target machining dwell time, the second target machining dwell time, the second circular machining trajectory, and the first circular machining trajectory. It's important to note that Step 5 only performs speed matching on the circular machining trajectory to achieve collaborative machining; the spiral machining trajectory of the first grinding disc is still processed using the traditional single-disc spiral machining method. Step 5 converts the calculated theoretical dwell time into executable motion control parameters that match the actual movement of the workpiece stage, ensuring that the two grinding discs of different sizes can achieve collaborative machining without mutual interference.

[0039] Furthermore, in step 6, the first grinding disc is controlled to switch radial circular trajectories, the second grinding disc is controlled to switch radial circular trajectories, the axial orientation of the first grinding disc is controlled, and the axial orientation of the second grinding disc is controlled based on the processing parameters.

[0040] In some embodiments, in step 6, processing code is generated based on processing parameters, and the processing code is used to drive the corresponding braking mechanism, thereby controlling the processing state of the first grinding disc, the processing state of the second grinding disc, and the processing state of the workpiece table. For the collaborative processing area, the corresponding robotic arm is used to control the rotation of the grinding disc, the radial switching of the circular trajectory, and the adjustment of the grinding disc's posture, and then cooperates with the rotating workpiece table to achieve collaborative processing. The workpiece table drives the lens to rotate, changing the grinding disc's movement into the lens's rotation. The collaborative processing mode greatly reduces the difficulty of planning the anti-collision trajectory for the robot.

[0041] The simulation process was performed on an optical lens with a diameter of 400mm. The initial surface shape error distribution of the lens is shown in the figure below. Figure 1 As shown, the root mean square value of the initial surface shape of the lens is 1.68 × 10⁻⁶. -3 The surface roughness (mm) is achieved using only a flat rotating grinding wheel with a diameter of 80mm and an eccentricity of 8mm. The machining trajectory is a composite trajectory of circular and spiral lines, with a 20mm margin. The step distance and trajectory spacing are both 8mm. The simulated surface shape error distribution diagram is shown below. Figure 2 As shown, the root mean square value of the face error after simulation processing is 8.45 × 10⁻⁶. -4 mm, and after processing, a noticeably large annular pit appears near the edge of the mirror surface, introducing obvious edge ringing; using the dual-grinding-disc collaborative optical element processing method provided by this invention, a second grinding disk with a diameter of 20 mm and an eccentricity of 3 mm and a first grinding disk with a diameter of 80 mm and an eccentricity of 8 mm are used for collaborative processing. The width of the processing area of ​​the second grinding disk is 30 mm, the width of the second annular processing area is 10 mm, the edge of the circular trajectory of the second grinding disk is 5 mm, and the step distance and trajectory spacing are both 3 mm. Reference Figure 3 The machining trajectory of the first grinding wheel is a composite trajectory of circular and spiral lines (red trajectory on a white background), with a step size and trajectory spacing of 8mm. The machining trajectory of the second grinding wheel is a circular trajectory (red trajectory on a blue background). The red dots on the red trajectory represent dwell points. The surface shape error distribution diagram after simulation machining is shown below. Figure 4 As shown, the root mean square value of the face error after simulation processing is 2.10 × 10⁻⁶. -4 mm, it can be seen that the surface accuracy has been significantly improved, and the pit size near the edge of the mirror surface processed by the method of the present invention is smaller and shallower, which also plays a certain role in suppressing edge ringing.

[0042] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0043] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for fabricating optical elements using a dual-grinding-disc method, characterized in that, include: Step 1: Determine the surface shape error data; Step 2: Select the first grinding disc and the second grinding disc. The size of the first grinding disc is larger than the size of the second grinding disc. Obtain the removal function for the first grinding disc and the removal function for the second grinding disc. Step 3: Determine the first grinding disc processing area and the second grinding disc processing area. Plan the second circular processing trajectory based on the second grinding disc processing area and the first circular processing trajectory based on the first grinding disc processing area. In Step 3, determining the first grinding disc processing area and the second grinding disc processing area includes: dividing the processing area of ​​the lens to be processed into a central processing area and a collaborative processing area. The collaborative processing area surrounds the central processing area. The central processing area is the area processed by the first grinding disc using a spiral trajectory. The collaborative processing area includes a first annular processing area, a second annular processing area, and a third annular processing area. The second annular processing area surrounds the first annular processing area, and the third annular processing area surrounds the second annular processing area. The first annular processing area is the area processed by the first grinding disc using a circular trajectory; the second annular processing area is the area processed by both the first and second grinding discs using a circular trajectory; the third annular processing area is the area processed by the second grinding disc using a circular trajectory; the first annular processing area and the second annular processing area constitute the first grinding disc processing area; the second annular processing area and the third annular processing area constitute the second grinding disc processing area. Step 4: Based on the removal function of the first grinding wheel, the removal function of the second grinding wheel, and the surface error data, obtain the first target processing dwell time of each dwell point in the first circular ring processing trajectory, and obtain the second target processing dwell time of each dwell point in the second circular ring processing trajectory; Step 5: Determine the processing parameters based on the first target processing dwell time, the second target processing dwell time, the second circular ring processing trajectory, and the first circular ring processing trajectory; Step 6: Based on the processing parameters, control the workpiece rotation, control the first grinding disc rotation, and control the second grinding disc rotation, so that while the first grinding disc processes the processing area of ​​the first grinding disc, the second grinding disc processes the processing area of ​​the second grinding disc.

2. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 1, characterized in that, In step 1, determining the surface shape error data includes: determining the target surface shape data of the target lens, obtaining the unprocessed surface shape data of the lens to be processed, and determining the surface shape error data based on the unprocessed surface shape data and the target surface shape data.

3. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 1, characterized in that, In step 2, obtaining the removal function of the first grinding disc includes: using the first grinding disc to perform single-point polishing on the experimental piece with the same material as the lens to be processed, forming a first polishing spot, the rotation speed of the first grinding disc is the first initial rotation speed, the pressure of the first grinding disc is the first initial pressure, measuring the three-dimensional morphology of the first polishing spot to obtain the depth distribution of the first polishing spot, and dividing the depth distribution of the first polishing spot by the corresponding polishing time to obtain the removal function of the first grinding disc under the first initial rotation speed and the first initial pressure; Obtaining the removal function of the second grinding disc includes: using the second grinding disc to perform single-point polishing on the experimental piece with the same material as the lens to be processed, forming a second polishing spot, the rotation speed of the second grinding disc is the second initial rotation speed, the pressure of the second grinding disc is the second initial pressure, measuring the three-dimensional morphology of the second polishing spot to obtain the depth distribution of the second polishing spot, and dividing the depth distribution of the second polishing spot by the corresponding polishing time to obtain the removal function of the second grinding disc under the second initial rotation speed and the second initial pressure.

4. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 1, characterized in that, In step 3, the width of the processing area of ​​the second grinding disc is not less than the sum of the diameter of the first grinding disc and the safe distance from the center of the first grinding disc to the edge of the mirror.

5. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 1, characterized in that, In step 6, the workpiece stage drives the lens to be processed to rotate and the first grinding disc to rotate, so that the first grinding disc completes the processing of the first grinding disc processing area along the first circular processing trajectory. The workpiece stage rotates and the second grinding disc rotates, so that the second grinding disc completes the processing of the second grinding disc processing area along the second circular processing trajectory. While the second grinding disc is processing along any one of the two circular processing trajectories, the first grinding disc is processing along any one of the two circular processing trajectories, and the relative positions of the first grinding disc and the second grinding disc remain unchanged. After the second grinding wheel completes the processing of its processing area, a robotic arm connected to the second grinding wheel is used to carry the second grinding wheel out of the processing area. The first grinding wheel continues to process until it completes the processing of its processing area. Then, the workpiece table stops rotating, and a robotic arm connected to the first grinding wheel drives the first grinding wheel to complete the processing of the central processing area along a spiral trajectory.

6. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 1, characterized in that, In step 4, the material convolution removal model is used to obtain the first target processing dwell time and the second target processing dwell time based on the removal function of the first grinding disc, the removal function of the second grinding disc, and the surface error data. The formula for the material convolution removal model is as follows: ;in, This represents a two-dimensional convolution operation. Represents surface shape error data. This represents the removal function of the first grinding disc. Indicates the dwell time for the first target processing. This represents the removal function for the second grinding disc. This indicates the dwell time for processing the second target.

7. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 6, characterized in that, Step 3 also includes: calculating the normal vector of the first mirror dwell point corresponding to the first ring machining trajectory and the normal vector of the second mirror dwell point corresponding to the second ring machining trajectory; The calculation of the normal vector of the first mirror dwell point includes: the machining trajectory of the first annulus is , This represents the three-dimensional coordinates of the dwell point on the machining trajectory of the first ring. , , Represents the station number, This represents the total number of dwell points on the processing trajectory of the first circular ring. The representative serial number is outposts x Axis coordinates The representative serial number is outposts y Axis coordinates The representative serial number is outposts z Axial coordinates, three-dimensional coordinates are The normal vector of the first mirror dwell point of the dwell point ,in, Indicates the normal vector of the first mirror dwell point in x Components on the axis, Indicates the normal vector of the first mirror dwell point in y Components on the axis, Indicates the normal vector of the first mirror dwell point in z Components on the axis, Indicates the corresponding station location xy Coordinates on a plane Represents the target surface shape function pair x The first-order partial derivative, Represents the target surface shape function pair y The first partial derivative of the first grinding disc means that when the first grinding disc is processing at the corresponding dwell point, the axis of the first grinding disc coincides with the normal vector of the first mirror dwell point at the corresponding dwell point. The calculation of the normal vector of the second mirror dwell point includes: the machining trajectory of the second annulus is , This represents the three-dimensional coordinates of the dwell point on the machining trajectory of the second ring. , , Represents the station number, This represents the total number of dwell points on the machining trajectory of the second ring. The representative serial number is outposts x Axis coordinates The representative serial number is outposts y Axis coordinates The representative serial number is outposts z Axial coordinates, three-dimensional coordinates are The normal vector of the second mirror dwell point of the dwell point ,in, Indicates the normal vector of the second mirror dwell point in x Components on the axis, Indicates the normal vector of the second mirror dwell point in y Components on the axis, Indicates the normal vector of the second mirror dwell point in z Components on the axis, Indicates the corresponding station location xy Coordinates on a plane Indicates the target surface shape function at the corresponding dwell point. x The first-order partial derivative, Indicates the target surface shape function at the corresponding dwell point. y The first partial derivative of the second grinding wheel means that when the second grinding wheel is processing at the corresponding dwell point, the axis of the second grinding wheel coincides with the normal vector of the corresponding dwell point. Step 5 also includes: determining the machining parameters based on the first target machining dwell time, the second target machining dwell time, the second circular machining trajectory, the first circular machining trajectory, the normal vector of the first mirror dwell point, and the normal vector of the second mirror dwell point.

8. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 5, characterized in that, Step 5, determining the processing parameters includes: Step 51: Place the item with serial number... The first target processing stay time at the station This is converted into the target total number of revolutions of the first grinding disc at that dwell point. , with the serial number The second target processing stay time at the station This is converted into the target total number of revolutions of the second grinding disc at that dwell point. , ; ,in, This indicates the initial rotational speed of the first grinding disc. This indicates the initial rotational speed of the second grinding disc; Step 52: Set the rotational angular velocity of the workpiece stage. angular velocity of rotation Within the safe rotational speed range; Get the serial number as The first actual processing stay time at the station And obtain the serial number as The second actual processing stay time at the station , ； ； in, This represents the distance between adjacent dwell points on the machining trajectory of the first ring. This indicates the distance between adjacent dwell points on the machining trajectory of the second ring; Step 53: Based on the first actual processing dwell time Second, actual processing dwell time The total number of rotations of the first grinding disc at the corresponding dwell point. And the target total number of rotations at the corresponding dwell point of the second grinding disc. Obtain the first grinding disc at the sequence number. Actual rotational speed at the dwell point And obtain the second grinding disc at serial number Actual rotational speed at the dwell point The total number of revolutions of the same grinding disc at different resting points remains constant. ； ； Step 54: Determine whether the actual rotational speed corresponding to each dwell point is within the preset safe range. If the actual rotational speed of some dwell points exceeds the preset safe range, return to step 52 and adjust the rotational angular velocity of the workpiece stage. The iteration continues until the actual rotational speed at each dwell point is within the preset safety range, at which point the iteration stops and the final actual rotational speed is obtained. If the actual rotational speed of a certain revolution on the circular machining trajectory is higher than the preset safety range, the rotational speed of that revolution is adjusted to be within the preset safety range. And repeat the processing along the trajectory. Next, the final actual rotational speed, the machining trajectory of the first ring, the machining trajectory of the second ring, and the rotational angular velocity. As the processing parameters.

9. The method for fabricating dual-grinding-disc collaborative optical elements according to claim 1, characterized in that, In step 6, the first grinding disc is controlled to switch radial circular trajectories based on the processing parameters, the second grinding disc is controlled to switch radial circular trajectories, the axial orientation of the first grinding disc is controlled, and the axial orientation of the second grinding disc is controlled.

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