Magnetorheological polishing equipment and method for adjusting machining rotating speed based on machine vision

Abstract

The invention relates to the technical field of optical machining, in particular to magneto-rheological polishing equipment and method for adjusting the machining rotating speed based on machine vision, and the equipment comprises a robot, a control unit, a magneto-rheological machining module and machine vision equipment; the magneto-rheological processing module is arranged at the free end of the robot; the robot drives a polishing wheel in the magneto-rheological machining module to machine the optical element with magneto-rheological fluid as a medium, and machine vision equipment measures the ribbon thickness of the magneto-rheological fluid in the machining process; according to the method, the real-time change of the ribbon thickness of magnetorheological fluid in the magnetorheological machining process is measured through machine vision equipment, then parameters of the machining rotating speed are regulated and controlled in real time, and then real-time constant control over the removal function is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical processing, and particularly relates to a magnetorheological finishing device and method for adjusting the processing rotation speed based on machine vision. Background Technique

[0002] Magnetorheological Finishing (MRF) is an advanced optical manufacturing technology developed in recent years. It has many advantages such as a stable removal function, controllable edge effect, small subsurface damage layer, no copying effect, strong shaping ability, and high processing accuracy. Therefore, the magnetorheological finishing technology has received extensive attention in high-precision optical processing. The existing magnetorheological finishing devices mainly include three major parts in terms of hardware: a motion execution mechanism, a circulation system, and a polishing wheel module. Among them, the motion execution mechanism is mainly a numerical control machine tool. However, some deficiencies of the numerical control machine tool (such as low degrees of freedom, large floor area, high cost, etc.) limit the deviation amount of aspheres and it is difficult to perform precise pose control along the surface normal of the curved surface. The most important component in the circulation system is the supply source. Peristaltic pumps and centrifugal pumps are the main types of magnetorheological fluid supply sources currently. When a peristaltic pump is working, it will generate a pulse effect, which will affect the stability of the magnetorheological fluid during pipeline transportation and ultimately affect the stability of the removal function. The centrifugal pump has a small pulse effect when working, and the magnetorheological fluid is more stable during pipeline transportation and has a smaller impact on the change of the removal function. Therefore, it is more suitable for use as a magnetorheological supply system. However, there is still a relatively large problem when using a centrifugal pump as the supply source of the magnetorheological fluid supply system: when the outlet (nozzle) of the supply system moves up and down along the curved surface of the optical element during processing, the pressure between the centrifugal pump and the nozzle will change when the position of the centrifugal pump is constant. The originally stable magnetorheological fluid will also change, and the thickness and width of the ribbon formed by the magnetorheological fluid after passing through the polishing gap will also change accordingly, resulting in a change in the removal function and affecting the final processing accuracy.

[0003] In view of these deficiencies of the numerical control machine tool, researchers have introduced six-degree-of-freedom industrial robots into the field of optical processing in recent years. Six-degree-of-freedom industrial robots have the advantages of high degrees of freedom, small floor area, large processing range, low cost, etc., making up for the deficiencies of the numerical control machine tool. Therefore, when integrating the magnetorheological finishing module into an industrial robot, high-precision processing of large-aperture complex-curved optical elements can be theoretically achieved.

[0004] However, due to factors such as machining, assembly, load, trajectory planning, and reduction ratio, the execution accuracy of the free end of the robot is relatively low, and the polishing gap changes significantly during the machining process. At the same time, the magnetorheological polishing technology is an optical machining technology with a high degree of determinacy of the removal function, and it has high requirements for the change of the polishing gap during the polishing process. Generally, the change of the polishing gap in a magnetorheological numerical control machining center is in the order of dozens of micrometers (PV < 0.1 mm), while the trajectory accuracy of common commercial robots is generally in the sub-millimeter to millimeter range. This leads to a large change in the polishing gap during the machining process, and the thickness of the ribbon will change after the magnetorheological fluid passes through the polishing gap, reducing the determinacy of the removal function and affecting the final machining accuracy. Therefore, the motion accuracy of currently commercial large six-degree-of-freedom industrial robots often fails to meet the requirements of the magnetorheological polishing technology for the change of the removal function during high-precision polishing.

[0005] Regarding the problem of flow rate change in the centrifugal pump type supply system, the commonly used method at present is to add a follow-up device to keep the vertical distance between the centrifugal pump and the nozzle outlet unchanged. However, these methods require the additional follow-up device to have high motion performance to always keep the vertical distance from the nozzle unchanged. In some solutions, the follow-up device is even placed on the Z-axis of the numerical control machine tool, which undoubtedly increases the motion load and equipment cost of the motion mechanism, reduces the motion performance of the equipment, and the follow-up device cannot strictly guarantee the constancy of the vertical distance between the centrifugal pump and the nozzle, resulting in a change in the removal function and affecting the final machining accuracy. Summary of the Invention

[0006] In view of this, the present invention aims to provide a magnetorheological polishing device and method for adjusting the machining speed based on machine vision. By measuring the real-time change of the ribbon thickness of the magnetorheological fluid during the magnetorheological machining process through a machine vision device, and then real-time regulating the parameters of the machining speed, the real-time constant control of the removal function is realized.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows: A magnetorheological polishing device for adjusting the machining speed based on machine vision includes a robot, a control unit, a magnetorheological machining module, and a machine vision device. Among them: The magnetorheological machining module is arranged at the free end of the robot; the robot drives the polishing wheel in the magnetorheological machining module to process the optical element with magnetorheological fluid as the medium, and during the machining process, the machine vision device measures the ribbon thickness of the magnetorheological fluid. The control unit internally includes: a time calculation module, which calculates the measurement time of the machine vision device and the adjustment time of the magnetorheological machining module, and adjusts the machine vision device and the magnetorheological machining module according to the measurement time and the adjustment time; a conversion relationship module, which obtains a first conversion relationship based on the ribbon thickness and the polishing wheel speed of the polishing wheel, and obtains a second conversion relationship based on the ribbon thickness and the liquid pump speed of the liquid pump in the magnetorheological machining equipment; a real-time regulation module, which adjusts the polishing wheel speed or the liquid pump speed in combination with the conversion relationship, so as to keep the removal function stable when machining the optical element.

[0008] Furthermore, the magnetorheological machining module further includes a transmission belt, a polishing motor, a nozzle, a magnet, and a magnetorheological mounting bracket. Among them, the magnetorheological mounting bracket is arranged at the free end, and the polishing wheel is arranged on the magnetorheological mounting bracket; the polishing motor is connected to the polishing wheel through the transmission belt, so that the polishing motor controls the rotation of the polishing wheel and changes the polishing wheel speed; the nozzle is arranged on the magnetorheological mounting bracket along the rotation direction of the polishing wheel, and the liquid pump conveys magnetorheological fluid to the nozzle; the magnet is arranged on the magnetorheological mounting bracket and is close to the working point of the polishing wheel, so that the magnetorheological fluid is affected by the magnetic field intensity of the magnet and changes the stiffness of the magnetorheological fluid.

[0009] Furthermore, the robot, the machine vision device, the polishing motor, and the liquid pump are respectively connected to the control unit to form their respective communication lines, so that the control unit receives and sends signals through the corresponding communication lines.

[0010] A magnetorheological polishing method based on the polishing wheel speed, according to the magnetorheological polishing device for adjusting the machining speed based on machine vision provided by the present invention, includes the following steps: A1: Control the magnetorheological machining module to process the test optical element, and obtain the first conversion relationship through the conversion relationship module during the machining process; A2: Set the first variable range of the polishing wheel speed, and obtain the corresponding second variable range of the ribbon thickness according to the first conversion relationship; set the maximum polishing wheel speed, and obtain the corresponding maximum ribbon thickness according to the first conversion relationship; A3: Control the time calculation module to adjust the machine vision device and the magnetorheological machining module in combination with the maximum polishing wheel speed; A4: Process the optical element to be processed in combination with the second variable range, the maximum polishing wheel speed, and the maximum ribbon thickness. During the processing, the real-time control module adjusts the polishing wheel speed in real time.

[0011] Further, step A1 includes the following steps: A11: Control the polishing wheel to process the test optical element with different polishing gaps, calculate the volume removal rate of the removal function at each processing position, and measure the ribbon thickness at each processing position in real time through a machine vision device, and obtain the third conversion relationship between the ribbon thickness and the volume removal rate of the removal function in the conversion relationship module; A12: Individually change the polishing wheel speed, control the polishing wheel to process the test optical element at different polishing gaps, obtain the volume removal rate of the removal function at each processing position, and obtain the fourth conversion relationship between the volume removal rate of the removal function and the polishing wheel speed in the conversion relationship module; A13: Obtain the first conversion relationship according to the third conversion relationship and the fourth conversion relationship.

[0012] Further, in step A4, when controlling the polishing wheel to move to the current processing position, compare the current ribbon thickness measured by the machine vision device with the second variable range: If the current ribbon thickness is within the second variable range, there is no need to adjust the current polishing wheel speed; If the current ribbon thickness is not within the second variable range, the current polishing wheel speed needs to be adjusted: If the current ribbon thickness is greater than or equal to the maximum ribbon thickness, adjust the current polishing wheel speed to the maximum polishing wheel speed; If the current ribbon thickness is less than the maximum ribbon thickness, adjust the current polishing wheel speed according to the following formula: ; where, represents the first conversion relationship, represents the current ribbon thickness, represents the polishing wheel speed.

[0013] A magnetorheological polishing method based on the rotational speed of a liquid pump. According to the magnetorheological polishing equipment for adjusting the processing speed based on machine vision provided by the present invention, it includes the following steps: B1: Control the magnetorheological processing module to process the test optical element, and obtain the second conversion relationship through the conversion relationship module during the processing; B2: Set the third variable range of the liquid pump speed, and obtain the corresponding fourth variable range of the ribbon thickness according to the second conversion relationship; set the maximum liquid pump speed, and obtain the corresponding maximum ribbon thickness according to the second conversion relationship; B3: The control time calculation module adjusts the machine vision device and the magnetorheological processing module in combination with the maximum liquid pump speed. B4: Process the optical element to be processed in combination with the fourth variable range, the maximum liquid pump speed, and the maximum ribbon thickness. During the processing, the real-time control module adjusts the position of the electromagnet in real time.

[0014] Further, step B1 includes the following steps: B11: Control the polishing wheel to process the test optical element with different polishing gaps, calculate the volume removal rate of the removal function at each processing position, and at the same time, the machine vision device measures the ribbon thickness at each processing position to obtain the fifth conversion relationship between the volume removal rate of the removal function and the ribbon thickness in the conversion relationship module. B12: Individually change the liquid pump speed of the liquid pump, and control the polishing wheel to process the test optical element with different polishing gaps to obtain the volume removal rate of the removal function at each processing position, and obtain the sixth conversion relationship between the volume removal rate of the removal function and the liquid pump speed in the conversion relationship module. B13: Obtain the second conversion relationship according to the fifth conversion relationship and the sixth conversion relationship.

[0015] Further, in step B4, when controlling the polishing wheel to move to the current processing position, compare the current ribbon thickness measured by the machine vision device with the fourth variable range: If the current ribbon thickness is within the fourth variable range, there is no need to adjust the current liquid pump speed; If the current ribbon thickness is not within the fourth variable range, the current liquid pump speed needs to be adjusted: If the current ribbon thickness is greater than or equal to the maximum ribbon thickness, adjust the current liquid pump speed to the maximum liquid pump speed; If the current ribbon thickness is less than the maximum ribbon thickness, adjust the current liquid pump speed according to the following formula:

[0016] where, represents the second conversion relationship, represents the ribbon thickness, represents the current liquid pump speed.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: In the magnetorheological polishing equipment and method for adjusting the processing speed based on machine vision according to the present invention, the ribbon thickness of the magnetorheological fluid during six-dimensional processing driven by the robot by the machine vision device is measured in real time, so as to adjust the processing speed in the magnetorheological processing module in real time, and further realize the real-time constant control of the change of the removal function under the coupling of multiple factors during the processing of the optical element; at the same time, the acquisition of the pose information does not need to rely on the actual processing process, and the pose error information of the processing equipment can be obtained during the trial operation link of the processing (no magnetorheological fluid is introduced in this link and no processing effect is generated), and it is not necessary to place the measuring device at the lowest point of the polishing wheel, which will not affect the actual processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 FIG. is a schematic structural diagram of the magnetorheological polishing equipment for adjusting the processing speed based on machine vision according to an embodiment of the present invention from one perspective; Figure 2 FIG. is a schematic structural diagram of the magnetorheological polishing equipment for adjusting the processing speed based on machine vision according to an embodiment of the present invention from another perspective; Figure 3 FIG. is a schematic structural diagram of the liquid pump according to an embodiment of the present invention.

[0019] DESCRIPTION OF THE REFERENCE NUMERALS: 1. Robot; 2. Control unit; 3. Machine vision device; 4. Test bench; 5. Optical element to be processed; 6. Test optical element; 7. Polishing wheel; 8. Liquid pump; 9. Transmission belt; 10. Polishing motor; 11. Nozzle; 12. Magnet; 13. Magnetorheological mounting bracket; 14. Liquid pump body; 15. Cooling chamber; 16. Magnetorheological fluid storage chamber; 17. Cooling water inlet; 18. Magnetorheological fluid inlet; 19. Cooling water outlet; 20. Magnetorheological fluid outlet; 21. Mounting bracket; 22. Connecting plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0021] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0022] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more than two.

[0023] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0024] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0025] Such as Figure 1 and Figure 2As shown in the figure, the magnetorheological polishing equipment for adjusting the processing speed based on machine vision according to the embodiment of the present invention includes a robot 1, a control unit 2, a magnetorheological processing module, and a machine vision device 3. The magnetorheological processing module is installed at the free end of the robot 1. The robot 1 drives the polishing wheel 7 in the magnetorheological processing module to process the optical element 5 to be processed or the test optical element 6 placed on the experimental table 4 with magnetorheological fluid as the medium. The machine vision device 3 is installed on one side of the experimental table 4, and during the processing, the machine vision device 3 measures the ribbon thickness of the magnetorheological fluid. During the processing, the ribbon thickness of the magnetorheological fluid is affected by the supply system providing the magnetorheological fluid and the polishing gap, and the polishing gap is changed by the position of the polishing wheel, the pose adjustment of the robot, etc. Therefore, it is necessary to use the machine vision device 3 installed on one side of the experimental table 4 to measure the change in the ribbon thickness of the magnetorheological fluid in real time. In the embodiment of the present invention, the machine vision device 3 uses a binocular stereo camera of the Stereo ace model of Basler Company. The process of using the machine vision device 3 to measure the ribbon thickness of the magnetorheological fluid includes: the machine vision device 3 collects the contour information of the polishing wheel 7 and the ribbon. Taking any point in the non-working area of the surface of the polishing wheel 7 as the reference point, and the highest point on the surface of the ribbon of the magnetorheological fluid as the measurement point, the height difference between the measurement point and the reference point is the change data of the ribbon thickness.

[0026] The inside of the control unit 2 includes a time calculation module, a conversion relationship module, and a real-time regulation module. Among them, the time calculation module is used to calculate the measurement time of the machine vision device 3 and the adjustment time of the magnetorheological processing module, and adjust the machine vision device 3 and the magnetorheological processing module according to the measurement time and the adjustment time; the conversion relationship module is used to obtain the first conversion relationship according to the ribbon thickness and the polishing wheel speed of the polishing wheel 7, and obtain the second conversion relationship according to the ribbon thickness and the liquid pump speed of the liquid pump 8 in the magnetorheological processing equipment; the real-time regulation module is used to adjust the polishing wheel speed or the liquid pump speed in combination with the conversion relationship, so as to keep the removal function stable when processing the optical element 5 to be processed or the test optical element 6.

[0027] The magnetorheological processing module further includes a transmission belt 9, a polishing motor 10, a nozzle 11, a magnet 12, and a magnetorheological mounting bracket 13. Among them, the magnetorheological mounting bracket 13 is fixed on the free end of the robot 1, and the polishing wheel 7 is mounted on the magnetorheological mounting bracket 13. The polishing motor 10 is mounted on the magnetorheological mounting bracket 13, and the output end of the polishing motor 10 is connected to the polishing wheel 7 through the transmission belt 9, so that the polishing motor 10 controls the rotation of the polishing wheel 7 and changes the rotation speed of the polishing wheel. In the embodiment of the present invention, the manner in which the polishing motor 10 drives the polishing wheel 7 to rotate can refer to the invention patent application with the Chinese patent publication number CN118322074A, publication date July 12, 2024, and patent name "Self-rotating polishing module processing system". The nozzle 11 is mounted on the magnetorheological mounting bracket 13 along the rotation direction of the polishing wheel 7. The liquid pump 8 is mounted on one side of the test bench 4 through the mounting bracket 21, and the liquid pump 8 delivers the magnetorheological fluid to the nozzle 11. The nozzle 11 sprays the magnetorheological fluid onto the working point of the polishing wheel 7, so that the polishing wheel 7 processes the optical element 5 to be processed or the test optical element 6 with the magnetorheological fluid as the medium. The magnet 12 is mounted on the magnetorheological mounting bracket 13 through the connecting plate 22, and the magnet 12 is close to the working point of the polishing wheel 7, so that the magnetorheological fluid changes its stiffness under the influence of the magnetic field strength of the magnet 12. In the embodiment of the present invention, it is stipulated that the working point of the polishing wheel 7 is the point closest to the surface of the optical element 5 to be processed or the test optical element 6 along the normal direction of the surface of the optical element 5 to be processed or the test optical element 6.

[0028] The overall structure of the liquid pump 8 is as Figure 3 shown, including a liquid pump main body 14, a cooling chamber 15, and a magnetorheological fluid storage chamber 16. In the embodiment of the present invention, the liquid pump main body 14 adopts the DFLD vertical multistage pump of Shanghai Dongfang Pump Industry Company, and the liquid pump main body 14 is used to supply the magnetorheological fluid; the cooling chamber 15 is mainly used to store cooling water and cool down the magnetorheological fluid; the magnetorheological fluid storage chamber 16 is mainly used for storing the magnetorheological fluid. When the liquid pump 8 works, the cooling water enters the cooling chamber 15 from the cooling water inlet 17, and the magnetorheological fluid enters the liquid pump main body 14 from the magnetorheological fluid inlet 18 through the magnetorheological fluid storage chamber 16; the cooling water cools down the magnetorheological fluid in the cooling chamber 15 and then discharges from the cooling water outlet 19; the cooled magnetorheological fluid is output from the magnetorheological fluid outlet 20 and is delivered to the nozzle 11 through a pipeline. The liquid pump speed of the liquid pump 8 is adjusted by a motor, so that the liquid pump 8 changes the liquid pump speed.

[0029] The motors of the robot 1, the machine vision device 3, the polishing motor 10, and the liquid pump 8 are respectively connected to the control unit 2 to form their respective communication lines, enabling the control unit 2 to receive and send signals through the corresponding communication lines. Among them, the control unit 2 is communicatively connected to the motor through the communication line. During the working process, the control unit 2 sends speed control instructions in real time, and the motor adjusts the speed of the liquid pump 8 in real time, thereby achieving the purpose of adjusting the liquid flow rate. Since a strong magnetic region is generated around the polishing wheel 7 during the polishing operation, the communication line avoids the strong magnetic region.

[0030] Based on the magnetorheological polishing equipment for adjusting the processing speed based on machine vision described in the embodiments of the present invention, the embodiments of the present invention also provide a magnetorheological polishing method for adjusting the processing speed based on machine vision, including a magnetorheological polishing method based on the polishing wheel speed and a magnetorheological polishing method based on the liquid pump speed.

[0031] Specific Embodiment 1: The magnetorheological polishing method based on the polishing wheel speed provided in this specific embodiment, according to the magnetorheological polishing equipment for adjusting the processing speed based on machine vision in the embodiments of the present invention, combined with Figure 1 and Figure 2 , includes the following steps: A1: Control the magnetorheological processing module to process the test optical element 6, and obtain the first conversion relationship through the conversion relationship module during the processing. Step A1 includes the following steps: A11: Control the polishing wheel 7 to process the test optical element 6 at different polishing gaps, calculate the volume removal rate of the removal function at each processing position, and measure the ribbon thickness at each processing position in real time through the machine vision device 3. In the conversion relationship module, we get: ; where represents the third conversion relationship between the ribbon thickness T and the volume removal rate MRR of the removal function; in this specific embodiment, specifically control the magnetorheological processing module to perform fixed-point processing on the test optical element 6 for a period of time; A12: Independently change the polishing wheel speed, control the polishing wheel 7 to process the test optical element 6 at different polishing gaps, obtain the volume removal rate of the removal function at each processing position, and in the conversion relationship module, we get: ; where represents the fourth conversion relationship between the volume removal rate MRR of the removal function and the polishing wheel speed ; in this specific embodiment, specifically independently change the polishing wheel speed, and control the polishing wheel 7 to perform fixed-point processing on the test optical element 6 at different polishing gaps for a period of time; A13: Obtain the first conversion relationship according to the third conversion relationship and the fourth conversion relationship, i.e.:

[0032] wherein, represents the first conversion relationship.

[0033] A2: Set the first variable range of the polishing wheel speed , and obtain the second variable range corresponding to the ribbon thickness T according to the first conversion relationship , i.e.: ; ; Set the maximum polishing wheel speed , and obtain the corresponding maximum ribbon thickness according to the first conversion relationship , i.e.: .

[0034] The first variable range and the maximum polishing wheel speed are adaptively set according to the actual situation, and this specific embodiment does not limit this.

[0035] A3: The control time calculation module combines the maximum polishing wheel speed to adjust the machine vision device 3 and the magnetorheological processing module.

[0036] Step A3 includes the following steps: A31. Statistically analyze b data measured by the machine vision device 3 within a seconds to obtain the time for the machine vision device 3 to measure one point; ; A32. Calculate the time required to adjust the magnetorheological processing module when the change amount of the maximum polishing wheel speed changes: ; wherein, represents the change rate of the speed adjustment of the polishing wheel 7; A33. Measure the vertical distance from the measurement position of the machine vision device 3 to the working point of the polishing wheel 7, and calculate the time required for the polishing wheel 7 to rotate to the working point according to the vertical distance and the set polishing wheel speed : ; Among them, represents the radius of the polishing wheel 7; the rotational speed of the polishing wheel is adaptively set according to the actual situation, and this specific embodiment does not limit it; A34. Calculate the minimum movement time between two adjacent machining positions of the magnetorheological machining module at the maximum moving speed : : ; Among them, represents the distance between two adjacent machining positions; A35. Calculate whether the condition holds: If the condition holds, there is no need to adjust the machine vision device 3 and the polishing wheel 7; if the condition does not hold, it is necessary to adjust the data sampling frequency of the machine vision device 3 and the rotational speed of the polishing wheel to make the condition hold; A36. Perform mean filtering processing on the measurement data between every two adjacent machining positions and then output it. At the same time, the number of data for mean filtering needs to satisfy .

[0037] A4: Combine the second variable range , the maximum rotational speed of the polishing wheel and the maximum ribbon thickness , and machine the optical element 5 to be machined. During the machining process, the real-time control module adjusts the rotational speed V of the polishing wheel in real time. Specifically, it includes: when controlling the polishing wheel 7 to move to the current machining position i, compare the current ribbon thickness measured by the machine vision device 3 with the second variable range : If the current ribbon thickness is within the second variable range , that is, , there is no need to adjust the current rotational speed of the polishing wheel ; If the current ribbon thickness is not within the second variable range , that is, , it is necessary to adjust the current rotational speed of the polishing wheel : If the current ribbon thickness is greater than or equal to the maximum ribbon thickness , that is, , adjust the current rotational speed of the polishing wheel to the maximum rotational speed of the polishing wheel ; If the current ribbon thickness Less than the maximum ribbon thickness , that is , the current polishing wheel rotation speed is adjusted according to the following formula : .

[0038] Specific Embodiment 2: The magnetorheological polishing method based on the liquid pump rotation speed provided in this specific embodiment, according to the magnetorheological polishing equipment for adjusting the processing rotation speed based on machine vision in the embodiments of the present invention, in combination with Figures 1 to 3 , includes the following steps: B1: Control the magnetorheological processing module to process the test optical element 6, and obtain the second conversion relationship through the conversion relationship module during the processing. Step B1 includes the following steps: B11: Control the polishing wheel 7 to process the test optical element 6 with different polishing gaps, calculate the volume removal rate of the removal function at each processing position, and at the same time, the machine vision device 3 measures the ribbon thickness at each processing position in real time, and obtains in the conversion relationship module: ; wherein represents the fifth conversion relationship between the ribbon thickness T and the volume removal rate MRR of the removal function; in this specific embodiment, specifically control the polishing wheel 7 to perform fixed-point processing on the test optical element 6 for a period of time with different polishing gaps; B12: Independently change the liquid pump rotation speed of the liquid pump 8, control the polishing wheel 7 to process the test optical element 6 with different polishing gaps, obtain the volume removal rate of the removal function at each processing position, and obtain in the conversion relationship module: ; wherein represents the sixth conversion relationship between the volume removal rate MRR of the removal function and the liquid pump rotation speed ; in this specific embodiment, specifically independently change the liquid pump rotation speed of the liquid pump 8, and control the polishing wheel 7 to perform fixed-point processing on the test optical element 6 for a period of time with different polishing gaps; B13: Obtain the second conversion relationship according to the fifth conversion relationship and the sixth conversion relationship, that is:

[0039] wherein represents the second conversion relationship.

[0040] B2: Set the third variable range of the liquid pump rotation speed , and obtain the corresponding fourth variable range of the ribbon thickness according to the second conversion relationship , that is: ​ ; ; Set the maximum liquid pump speed , and according to the second conversion relationship Get the corresponding maximum ribbon thickness ,Right now: .

[0041] The third variable range and maximum liquid pump speed The configuration is adaptive according to the actual situation and is not limited in this embodiment.

[0042] B3: The control time calculation module is combined with the maximum liquid pump speed to adjust the machine vision device and the magnetorheological processing module. Step B3 includes the following steps: B31. Count b data points measured by machine vision device 3 within a second and obtain the time it takes for machine vision device 3 to measure one point. ; ; B32. Calculate the maximum liquid pump speed adjustment The time required to control the magnetorheological processing module : ; in, Indicates the rate of change of the speed adjustment of the liquid pump 8; B33, measure the vertical distance between the measuring position of the machine vision device 3 and the working point of the polishing wheel 7 , according to the vertical distance and the set polishing wheel speed Calculate the time required for the polishing wheel 7 to reach the working point : ; in, Indicates the radius of the polishing wheel 7; polishing wheel speed The configuration is adaptive according to the actual situation, and this embodiment does not limit this. B34. Calculate the maximum speed of the magnetorheological machining module Minimum moving time between two adjacent processing positions : ; in, Indicates the distance between two adjacent processing positions; B35. Calculation conditions Whether it holds: If the condition holds, there is no need to adjust the machine vision device 3 and the polishing wheel 7; if the condition does not hold, it is necessary to adjust the data sampling frequency of the machine vision device 3 and the rotation speed of the polishing wheel to make the condition hold; B36. After performing mean filtering on the measurement data between every two adjacent processing positions and then outputting it, the number of data for mean filtering needs to satisfy .

[0043] Since the magnetorheological fluid ejected from the liquid pump 8 needs to be transported through the pipeline and driven by the polishing wheel 7 to reach the working area, in order to ensure the adjustment of the removal function change at the target trajectory point, it is necessary to set the dwell time of each processing point. The specific setting method is as follows: Measure the Z-axis coordinate of the nozzle orifice position of the nozzle 11 through the machine vision device 3 and the Z-axis coordinate of the lowest point of the polishing wheel 7 , then the vertical distance between the nozzle orifice of the nozzle 11 and the lowest point of the polishing wheel 7 is |Z4 - Z5|, and the time required for the magnetorheological fluid ejected from the nozzle to reach the lowest point of the polishing wheel is : ; where n represents the number of revolutions per second of the polishing wheel 7, L represents the pipeline length, V represents the flow rate of the magnetorheological fluid. When generating the processing control program, if the dwell time of each point is such that the generated processing control program is appropriate; if there are dwell times for some processing points , it is necessary to increase the material removal thickness, extend the processing time, and regenerate the processing control program so that the processing dwell time of each point .

[0044] B4: Combine the fourth variable range , the maximum liquid pump speed and the maximum ribbon thickness , process the optical element 5 to be processed, and during the processing, the real-time regulation module adjusts the liquid pump speed in real time. In step B4, when controlling the polishing wheel 7 to move to the current processing position i, compare the current ribbon thickness measured by the machine vision device 3 with the fourth variable range : If the current ribbon thickness is within the fourth variable range , that is , then there is no need to adjust the current liquid pump speed ; If the current ribbon thickness Not within the fourth variable range That is , it is necessary to adjust the current liquid pump speed as follows: If the current ribbon thickness is greater than or equal to the maximum ribbon thickness , that is , adjust the current liquid pump speed to the maximum liquid pump speed ; If the current ribbon thickness is less than the maximum ribbon thickness , that is , adjust the current liquid pump speed according to the following formula: .

[0045] All the conversion relationships in the above specific embodiments are obtained by fitting. The fitting process includes and is not limited to importing discrete data into Matlab software and using the polyfit fitting instruction of Matlab software to complete data fitting and solve their respective conversion relationships; The Polyfit fitting instruction is a basic general instruction of matlab software. In this way, the corresponding relationships and corresponding function curves between relevant items can be seen more intuitively.

[0046] It should be understood that various forms of the processes shown above can be used, reordering, adding or deleting steps. For example, the steps recited in the disclosure of the present invention can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitation is made herein.

[0047] The above specific implementation manners do not constitute a limitation to the protection scope of the present 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 principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A magnetorheological polishing device for adjusting machining speed based on machine vision, characterized in that: It includes a robot, a control unit, a magnetorheological machining module and a machine vision device; wherein: the magnetorheological machining module is arranged at the free end of the robot; the robot drives a polishing wheel in the magnetorheological machining module to process an optical element with magnetorheological fluid as the medium, and during the processing, the machine vision device measures the ribbon thickness of the magnetorheological fluid; The interior of the control unit includes: A time calculation module that calculates the measurement time of the machine vision device and the adjustment time of the magnetorheological machining module, and adjusts the machine vision device and the magnetorheological machining module according to the measurement time and the adjustment time; A conversion relationship module that obtains a first conversion relationship according to the ribbon thickness and the polishing wheel speed of the polishing wheel, and obtains a second conversion relationship according to the ribbon thickness and the liquid pump speed of the liquid pump in the magnetorheological machining equipment; A real-time regulation module that adjusts the polishing wheel speed according to the first conversion relationship, or adjusts the liquid pump speed according to the second conversion relationship to keep the removal function stable during the processing of the optical element.

2. The magnetorheological polishing equipment for adjusting the processing speed based on machine vision according to claim 1, wherein: The magnetorheological machining module further includes a transmission belt, a polishing motor, a nozzle, a magnet and a magnetorheological mounting bracket; wherein, The magnetorheological mounting bracket is arranged on the free end, and the polishing wheel is arranged on the magnetorheological mounting bracket; The polishing motor is connected to the polishing wheel through the transmission belt, so that the polishing motor controls the polishing wheel to rotate and changes the polishing wheel speed; The nozzle is arranged on the magnetorheological mounting bracket along the rotation direction of the polishing wheel, and the liquid pump conveys magnetorheological fluid to the nozzle; The magnet is arranged on the magnetorheological mounting bracket and is close to the working point of the polishing wheel, so that the magnetorheological fluid is affected by the magnetic field strength of the magnet to change the stiffness of the magnetorheological fluid.

3. The magnetorheological polishing equipment for adjusting the processing speed based on machine vision according to claim 2, wherein: The robot, the machine vision device, the polishing motor and the liquid pump are respectively connected to the control unit to form their respective communication lines, so that the control unit receives and sends signals through the corresponding communication lines.

4. A magnetorheological polishing method based on the rotational speed of a polishing wheel, based on the magnetorheological polishing equipment for adjusting the processing rotational speed based on machine vision according to any one of claims 1 to 3, characterized in that: It includes the following steps: A1: Control the magnetorheological machining module to process a test optical element, and obtain the first conversion relationship through the conversion relationship module during the processing; A2: Set a first variable range of the polishing wheel speed, and obtain a corresponding second variable range of the ribbon thickness according to the first conversion relationship; set the maximum polishing wheel speed, and obtain the corresponding maximum ribbon thickness according to the first conversion relationship; A3: Control the time calculation module to adjust the machine vision device and the magnetorheological machining module in combination with the maximum polishing wheel speed; A4: Process the optical element to be processed in combination with the second variable range, the maximum polishing wheel speed and the maximum ribbon thickness, and during the processing, the real-time regulation module adjusts the polishing wheel speed in real time.

5. The magnetorheological polishing method based on the rotational speed of the polishing wheel according to claim 4, wherein: Step A1 includes the following steps: A11: Control the processing of the test optical element by the polishing wheel with different polishing gaps, calculate the volume removal rate of the removal function at each processing position, and measure the ribbon thickness at each processing position in real time through the machine vision device, and obtain the third conversion relationship between the ribbon thickness and the volume removal rate of the removal function in the conversion relationship module; A12: Independently change the polishing wheel speed, control the processing of the test optical element by the polishing wheel with different polishing gaps, obtain the volume removal rate of the removal function at each processing position, and obtain the fourth conversion relationship between the volume removal rate of the removal function and the polishing wheel speed in the conversion relationship module; A13: Obtain the first conversion relationship according to the third conversion relationship and the fourth conversion relationship.

6. The magnetorheological polishing method based on the rotational speed of the polishing wheel according to claim 5, wherein: In step A4, when controlling the polishing wheel to move to the current processing position, compare the currently measured ribbon thickness by the machine vision device with the second variable range: If the current ribbon thickness is within the second variable range, there is no need to adjust the current polishing wheel speed; If the current ribbon thickness is not within the second variable range, the current polishing wheel speed needs to be adjusted: If the current ribbon thickness is greater than or equal to the maximum ribbon thickness, adjust the current polishing wheel speed to the maximum polishing wheel speed; If the current ribbon thickness is less than the maximum ribbon thickness, adjust the current polishing wheel speed according to the following formula: ； Among them, represents the first conversion relationship, represents the current ribbon thickness, represents the current polishing wheel rotation speed.

7. A magnetorheological polishing method based on the rotational speed of a liquid pump, based on the magnetorheological polishing equipment for adjusting the processing rotational speed based on machine vision according to any one of claims 1 to 3, characterized in that: It includes the following steps: B1: Control the magnetorheological processing module to process the test optical element, and obtain the second conversion relationship through the conversion relationship module during the processing; B2: Set the third variable range of the liquid pump speed, and obtain the corresponding fourth variable range of the ribbon thickness according to the second conversion relationship; set the maximum liquid pump speed, and obtain the corresponding maximum ribbon thickness according to the second conversion relationship; B3: Control the time calculation module to adjust the machine vision device and the magnetorheological processing module in combination with the maximum liquid pump speed; B4: Process the optical element to be processed in combination with the fourth variable range, the maximum liquid pump speed and the maximum ribbon thickness, and during the processing, the real-time regulation module adjusts the liquid pump speed in real time.

8. The magnetorheological polishing method based on the rotational speed of the liquid pump according to claim 7, wherein: Step B1 includes the following steps: B11: Control the processing of the test optical element by the polishing wheel with different polishing gaps, calculate the volume removal rate of the removal function at each processing position, and at the same time, the machine vision device measures the ribbon thickness at each processing position in real time, and obtain the fifth conversion relationship between the volume removal rate of the removal function and the ribbon thickness in the conversion relationship module; B12: Independently change the liquid pump speed of the liquid pump, and control the processing of the test optical element by the polishing wheel with different polishing gaps, obtain the volume removal rate of the removal function at each processing position, and obtain the sixth conversion relationship between the volume removal rate of the removal function and the liquid pump speed in the conversion relationship module; B13: Obtain the second conversion relationship according to the fifth conversion relationship and the sixth conversion relationship.

9. The magnetorheological polishing method based on the rotational speed of a liquid pump according to claim 8, wherein: In step B4, when controlling the polishing wheel to move to the current machining position, compare the currently measured ribbon thickness by the machine vision device with the fourth variable range: If the currently measured ribbon thickness is within the fourth variable range, there is no need to adjust the current rotational speed of the liquid pump; If the currently measured ribbon thickness is not within the fourth variable range, it is necessary to adjust the current rotational speed of the liquid pump: If the currently measured ribbon thickness is greater than or equal to the maximum ribbon thickness, adjust the current rotational speed of the liquid pump to the maximum rotational speed of the liquid pump; If the current ribbon thickness is less than the maximum ribbon thickness, adjust the current liquid pump rotation speed according to the following formula: Among them, represents the second conversion relationship, represents the current ribbon thickness, represents the current liquid pump speed.

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