Magnetorheological polishing system based on electromagnetic flowmeter sensing and polishing method thereof

Abstract

The invention relates to the technical field of magneto-rheological polishing, in particular to a magneto-rheological polishing system based on sensing of an electromagnetic flowmeter and a polishing method of the magneto-rheological polishing system based on sensing of the electromagnetic flowmeter. By controlling the rotating speed of the liquid pump and controlling the output displacement of the actuator set, the height of the liquid pump, the position of the nozzle and the rotating speed of the polishing wheel, coarse and fine two-stage adjustment of the magnetorheological fluid flow fluctuation is achieved, so that the magnetorheological fluid flow fluctuation of each polishing point meets the high-precision polishing requirement, and it is guaranteed that a removal function is constant in the polishing process. An additional follow-up device is not needed, the equipment cost is lower, the flow change is small, and the flow fluctuation of the magnetorheological fluid is more stable.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetorheological polishing, and particularly to a magnetorheological polishing system based on electromagnetic flowmeter sensing and a polishing method thereof. Background Art

[0002] Magnetorheological Finishing (MRF) is an advanced optical manufacturing and processing 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, magnetorheological polishing technology has received extensive attention in high-precision optical processing. The existing magnetorheological polishing technology mainly integrates the magnetorheological polishing module on a numerically controlled machine tool. The supply system of the magnetorheological polishing module mainly uses a centrifugal pump as the supply source. However, there is still a major problem with using a centrifugal pump as the supply source of the supply system: when the nozzle of the magnetorheological polishing module processes along the curved surface of the optical element, the nozzle will move up and down with the tool end of the industrial robot within the working area. When the position of the centrifugal pump is constant, the pressure between the centrifugal pump and the nozzle will change, and the originally stable magnetorheological fluid will also change, resulting in a change in the removal function and affecting the final processing accuracy.

[0003] To address this problem, the commonly used method at present is to add a follow-up device to keep the vertical distance between the centrifugal pump and the liquid outlet of the nozzle constant. However, this method requires an additional follow-up device with high motion performance to always keep the vertical distance between the centrifugal pump and the liquid outlet of the nozzle constant. Some solutions even place the follow-up device on the Z-axis of the numerically controlled machine tool, which undoubtedly increases the motion load of the motion mechanism and the equipment cost, reduces the motion performance of the equipment, and the follow-up device cannot strictly ensure that the vertical distance between the centrifugal pump and the liquid outlet of the nozzle is constant. Therefore, the height difference between the centrifugal pump and the nozzle often changes at all times, affecting the stability of the magnetorheological fluid in the magnetorheological supply system, resulting in a change in the removal function during the processing, affecting the processing result, and increasing the equipment cost. Summary of the Invention

[0004] The purpose of the present invention is to provide a magnetorheological polishing system based on electromagnetic flowmeter sensing and a polishing method thereof to solve the problem that the existing technology cannot ensure a constant removal function during the processing even with the addition of a follow-up device.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A magnetorheological polishing system based on electromagnetic flowmeter sensing includes: A polishing platform, on which an element to be polished and a test polishing element are arranged; A polishing component, comprising an industrial robot and a magnetorheological polishing module. The industrial robot is used to drive the magnetorheological polishing module to move to the position where the test polishing element is located or the position where the element to be polished is located. The magnetorheological polishing module is used to polish the element to be polished or the test polishing element. The magnetorheological polishing module includes a magnetorheological mounting bracket, a polishing wheel, a nozzle, a magnet, an actuator group and a supply device. One end of the actuator group is connected to the magnetorheological mounting bracket, and the other end of the actuator group is connected to the tool end of the industrial robot. The polishing wheel, the nozzle and the magnet are respectively mounted on the magnetorheological mounting bracket. The nozzle is used to spray magnetorheological fluid onto the polishing wheel. The magnet is used to change the stiffness of the magnetorheological fluid. The polishing wheel is used to polish the test polishing element or the element to be polished. The supply device is arranged on one side of the polishing platform and is used to pump magnetorheological fluid into the nozzle. An electromagnetic flowmeter, arranged on the industrial robot, is used to monitor the flow rate of the magnetorheological fluid at the liquid outlet of the nozzle. A laser tracker, arranged on one side of the polishing platform, is used in cooperation with a target ball to measure the vertical distance between the nozzle and the liquid pump. A computer is used to respectively establish a first conversion relationship between the vertical distance and the liquid pump speed, a second conversion relationship between the polishing gap and the flow rate of the magnetorheological fluid, a third conversion relationship between the height of the liquid pump and the flow rate of the magnetorheological fluid, a fourth conversion relationship between the nozzle position and the flow rate of the magnetorheological fluid, and a fifth conversion relationship between the polishing wheel speed and the flow rate of the magnetorheological fluid according to the flow rate of the magnetorheological fluid monitored by the electromagnetic flowmeter, and adjust the liquid pump speed, the output displacement of the actuator group, the height of the liquid pump, the nozzle position and the polishing wheel speed according to the first to fifth conversion relationships to maintain the removal function of each polishing point of the element to be polished constant. And the computer is used to establish a sixth conversion relationship between the removal function and the flow rate of the magnetorheological fluid according to the flow rate of the magnetorheological fluid monitored by the electromagnetic flowmeter, and obtain a variable removal function set according to the sixth conversion relationship to perform secondary polishing on the element to be polished.

[0006] Furthermore, the supply device includes a liquid pump, a mounting bracket, a mounting plate, a linear guide rail and a ball screw stepping motor. Among them, the linear guide rail and the ball screw stepping motor are respectively vertically mounted on the mounting bracket, and the linear guide rails are distributed on both sides of the ball screw stepping motor. The liquid pump is mounted on the mounting plate, and the mounting plate is respectively connected to the slider of the linear guide rail and the nut of the ball screw stepping motor.

[0007] Further, the nozzle is installed on the magnetorheological mounting bracket through a nozzle adjusting seat, and the position of the nozzle relative to the polishing wheel is adjusted through the nozzle adjusting seat; the nozzle adjusting seat includes a fixing bracket, a nozzle adjusting motor, a pushing plate, a nozzle mounting bracket, and an arc-shaped guide rail; wherein, the fixing bracket is installed on the magnetorheological mounting bracket, the nozzle adjusting motor and the arc-shaped guide rail are respectively installed on the fixing bracket, the pushing plate is installed at the output end of the nozzle adjusting motor, the nozzle mounting bracket is respectively connected to the pushing plate and the slider of the arc-shaped guide rail, and the nozzle is installed on the nozzle mounting bracket.

[0008] Further, the magnetorheological polishing module further includes a polishing wheel driving device, and the polishing wheel driving device includes a driving motor, a motor connecting plate, a driving wheel, a driven wheel, and a synchronous belt. The driving motor is installed on the connecting plate, a bearing seat is installed on the connecting plate, a bearing is installed in the bearing seat, the bearing is connected to the polishing wheel, the driven wheel is sleeved on the bearing, the driving wheel is sleeved on the output end of the driving motor, and the synchronous belt is tensioned between the driven wheel and the driving wheel.

[0009] A magnetorheological polishing method for adjusting the polishing gap based on an actuator is realized by using the above-mentioned magnetorheological polishing system based on an electromagnetic flowmeter, and includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through the electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; wherein, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, set different polishing gaps, measure the magnetorheological fluid flow rate corresponding to different polishing gaps at each vertical distance through the electromagnetic flowmeter, obtain the discrete data of the polishing gap and the magnetorheological fluid flow rate at each vertical distance, and obtain the second conversion relationship between the polishing gap and the corresponding magnetorheological fluid flow rate at each vertical distance through data fitting. The second conversion relationship can be expressed as , where represents the polishing gap at each vertical distance, represents the magnetorheological fluid flow rate corresponding to the polishing gap at each vertical distance, represents the conversion relationship between the polishing gap and the magnetorheological fluid flow rate at each vertical distance; S2: Based on the height variation of the curved surface of the element to be polished, calculate the change in the rotational speed of the liquid pump according to the first conversion relationship, obtain the theoretical rotational speed of the liquid pump corresponding to each polishing point of the element to be polished, polish the element to be polished according to the theoretical rotational speed of each polishing point, and simultaneously monitor the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point in real time through an electromagnetic flowmeter and send it to the computer; where the theoretical rotational speed of the liquid pump is expressed as , where represents the theoretical rotational speed of the liquid pump at each polishing point, i = 1, 2, 3... m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point; S3: Set the allowable range of flow rate fluctuations in the computer, determine whether the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set allowable range of flow rate fluctuations. If it does not exceed, keep the polishing gap at the polishing point unchanged. If it exceeds, control the output displacement of the actuator group, and then adjust the polishing gap until the actual magnetorheological fluid flow rate does not exceed the allowable range of flow rate fluctuations to maintain the removal function constant at each polishing point.

[0010] Further, when polishing each polishing point of the element to be polished, set a dwell time for each polishing point, which specifically includes the following steps: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform, place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow velocity of the magnetorheological fluid, represents the radius of the polishing wheel.

[0011] Further, when the computer generates the polishing control program, if the dwell time of each polishing point , then the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point 。

[0012] Further, in step S3, the maximum adjustment amount of the output displacement of the actuator group is set in the computer to be ; and, If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is within the set flow rate fluctuation tolerance range , keep the polishing gap of the polishing point unchanged; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the adjustment amount of the output displacement of the current actuator group , then adjust the output displacement of the current actuator group according to the following formula : ; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the adjustment amount of the output displacement of the current actuator group , then adjust the output displacement of the current actuator group according to the following formula : ; Wherein, represents the initial output displacement of the actuator group.

[0013] A magnetorheological polishing method based on the height adjustment of a liquid pump, implemented by using the above-mentioned magnetorheological polishing system based on an electromagnetic flowmeter, includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through the electromagnetic flowmeter, if the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; wherein, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, different polishing clearances are set, different liquid pump heights are set at each polishing clearance, the flow rate of the magnetorheological fluid corresponding to different liquid pump heights at each polishing clearance is measured by an electromagnetic flowmeter, discrete data of the liquid pump height and the magnetorheological fluid flow rate at each polishing clearance are obtained, and a third conversion relationship between the liquid pump height and the corresponding magnetorheological fluid flow rate at each polishing clearance is obtained through data fitting. The third conversion relationship can be expressed as , where represents the liquid pump height at each polishing clearance, represents the flow rate of the magnetorheological fluid corresponding to the liquid pump height at each polishing clearance, represents the conversion relationship between the liquid pump height and the magnetorheological fluid flow rate at each polishing clearance; S2: According to the surface height change of the element to be polished, calculate the change of the liquid pump speed based on the first conversion relationship to obtain the theoretical liquid pump speed corresponding to each polishing point of the element to be polished. Polish the element to be polished according to the theoretical liquid pump speed of each polishing point. At the same time, the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point is monitored in real time by an electromagnetic flowmeter and sent to the computer; where the theoretical liquid pump speed is expressed as , where represents the theoretical liquid pump speed of each polishing point, i = 1, 2, 3... m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point; S3: Set a flow rate fluctuation tolerance range in the computer, and judge whether the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set flow rate fluctuation tolerance range. If it does not exceed, keep the liquid pump height of the polishing point unchanged. If it exceeds, control the ball screw stepping motor to adjust the liquid pump height of the polishing point until the actual flow rate of the magnetorheological fluid does not exceed the flow rate fluctuation tolerance range to maintain the removal function of each polishing point constant.

[0014] Further, when polishing each polishing point of the element to be polished, a dwell time is set for each polishing point, which specifically includes the following steps: S210: Establish a measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform. Place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

[0015] Further, when the computer generates the polishing control program, if the dwell time of each polishing point is, then the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

[0016] Further, in step S3, the maximum adjustment amount of the liquid pump height is set in the computer to be ; and, If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is within the set flow rate fluctuation tolerance range , keep the liquid pump height of the polishing point unchanged; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current liquid pump height adjustment amount is, then adjust the current liquid pump height according to the following formula : ; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current liquid pump height adjustment amount is, then adjust the current liquid pump height according to the following formula : ; Wherein, represents the initial height of the liquid pump.

[0017] A magnetorheological polishing method based on nozzle position adjustment, implemented by using the above-mentioned magnetorheological polishing system sensed by an electromagnetic flowmeter, includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element. Polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; where the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, set different polishing gaps, set different nozzle positions at each polishing gap, measure the magnetorheological fluid flow rate corresponding to different nozzle positions at each polishing gap through an electromagnetic flowmeter, obtain the discrete data of the nozzle position and the magnetorheological fluid flow rate at each polishing gap, and obtain the fourth conversion relationship between the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap through data fitting. The fourth conversion relationship can be expressed as , where represents the nozzle position at each polishing gap, represents the magnetorheological fluid flow rate corresponding to the nozzle position at each polishing gap, represents the conversion relationship between the nozzle position and the magnetorheological fluid flow rate at each polishing gap; S2: According to the surface height change of the element to be polished, calculate the change of the liquid pump speed based on the first conversion relationship, obtain the theoretical liquid pump speed corresponding to each polishing point of the element to be polished, polish the element to be polished according to the theoretical liquid pump speed of each polishing point, and at the same time, monitor the actual magnetorheological fluid flow rate at the nozzle outlet corresponding to each polishing point through an electromagnetic flowmeter in real time and send it to the computer; where the theoretical liquid pump speed is expressed as , where represents the theoretical liquid pump speed of each polishing point, i = 1, 2, 3... m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point; S3: Set the flow rate fluctuation tolerance range in the computer, judge whether the actual magnetorheological fluid flow rate at the nozzle outlet corresponding to each polishing point exceeds the set flow rate fluctuation tolerance range. If it does not exceed, keep the nozzle position of the polishing point unchanged. If it exceeds, control the nozzle adjustment motor to adjust the nozzle position of the polishing point until the actual magnetorheological fluid flow rate does not exceed the flow rate fluctuation tolerance range to maintain the removal function of each polishing point constant.

[0018] Furthermore, when polishing each polishing point of the polishing element, a dwell time is set for each polishing point, and the specific steps are as follows: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform. Place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

[0019] Furthermore, when the computer generates the polishing control program, if the dwell time of each polishing point is, then the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

[0020] Furthermore, in step S3, the maximum adjustment amount of the nozzle position is set in the computer to be ; and If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is within the set flow rate fluctuation tolerance range , keep the nozzle position of the polishing point unchanged; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current nozzle position adjustment amount is, then adjust the current nozzle position according to the following formula : ; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current nozzle position adjustment amount When it is, the current nozzle position is adjusted according to the following formula : ; Wherein, represents the initial position of the nozzle.

[0021] A magnetorheological polishing method based on the adjustment of the polishing wheel speed, which is realized by using the above-mentioned magnetorheological polishing system sensed by an electromagnetic flowmeter, includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate at each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through the electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; wherein, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, set different polishing gaps, set different polishing wheel speeds at each polishing gap, measure the magnetorheological fluid flow rate corresponding to different polishing wheel speeds at each polishing gap through the electromagnetic flowmeter, obtain the discrete data of the polishing wheel speed and the magnetorheological fluid flow rate at each polishing gap, and obtain the fifth conversion relationship between the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap through data fitting. The fifth conversion relationship can be expressed as , wherein, represents the polishing wheel speed at each polishing gap, represents the magnetorheological fluid flow rate corresponding to the polishing wheel speed at each polishing gap, represents the conversion relationship between the polishing wheel speed and the magnetorheological fluid flow rate at each polishing gap; S2: According to the surface height change of the element to be polished, calculate the change of the liquid pump speed based on the first conversion relationship, obtain the theoretical liquid pump speeds corresponding to each polishing point of the element to be polished, polish the element to be polished according to the theoretical liquid pump speeds of each polishing point, and at the same time, monitor the actual magnetorheological fluid flow rate at the nozzle liquid outlet corresponding to each polishing point in real time through the electromagnetic flowmeter and send it to the computer; wherein, the theoretical liquid pump speed is expressed as , wherein, represents the theoretical liquid pump speed of each polishing point, i = 1, 2, 3... m, and m represents the number of polishing points, Represents the vertical distance of the i-th polishing point; S3: Set the allowable range of flow rate fluctuation in the computer, and determine whether the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set allowable range of flow rate fluctuation. If it does not exceed, keep the rotational speed of the polishing wheel at the polishing point unchanged. If it exceeds, control the drive motor to adjust the rotational speed of the polishing wheel at the polishing point until the actual flow rate of the magnetorheological fluid does not exceed the allowable range of flow rate fluctuation, so as to maintain the constant removal function of each polishing point.

[0022] Furthermore, when polishing each polishing point of the element to be polished, a dwell time is set for each polishing point, which specifically includes the following steps: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform. Place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological fluid supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow velocity of the magnetorheological fluid, represents the radius of the polishing wheel.

[0023] Furthermore, when the computer generates the polishing control program, if the dwell time of each polishing point is, then the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

[0024] Furthermore, in step S3, set the maximum adjustment amount of the rotational speed of the polishing wheel in the computer to be ; and, If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set allowable range of flow rate fluctuation , keep the rotational speed of the polishing wheel at the current polishing point unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point outside the set flow fluctuation tolerance range and the current polishing wheel speed adjustment amount is, then adjust the current polishing wheel speed according to the following formula : ; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is outside the set flow fluctuation tolerance range and the current polishing wheel speed adjustment amount is, then adjust the current polishing wheel speed according to the following formula : ; wherein, represents the initial speed of the polishing wheel.

[0025] A magnetorheological polishing method based on removal function adjustment, implemented by using the above magnetorheological polishing system based on electromagnetic flowmeter sensing, includes the following steps: S1: Set the theoretical initial value of the magnetorheological fluid flow rate at each polishing point of the test polishing element, polish the test polishing element according to the theoretical initial value of the magnetorheological fluid flow rate to obtain the removal function, and at the same time measure the theoretical magnetorheological fluid flow rate corresponding to each polishing point of the test polishing element through the electromagnetic flowmeter, and calculate the sixth conversion relationship between the removal function and the theoretical magnetorheological fluid flow rate, wherein the sixth conversion relationship is expressed as , represents the removal function, represents the theoretical magnetorheological fluid flow rate at each polishing point of the test polishing element, represents the sixth conversion relationship between the theoretical magnetorheological fluid flow rate at each polishing point of the test polishing element and the removal function; S2: Set the flow fluctuation tolerance range in the computer, polish the element to be polished for the first time according to the theoretical magnetorheological fluid flow rate, measure the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point of the element to be polished through the electromagnetic flowmeter, and judge whether it exceeds the set flow fluctuation tolerance range. If it exceeds, record the actual magnetorheological fluid flow rate of the polishing point. After the element to be polished is polished for the first time, solve the removal function corresponding to the actual magnetorheological fluid flow rate of each recorded polishing point based on the sixth conversion relationship to obtain a set of variable removal functions; S3: Polish the element to be polished for the second time according to the set of variable removal functions, and determine the polishing amount at each polishing point when polishing the element to be polished for the second time through the set of variable removal functions.

[0026] Compared with the prior art, the present invention uses an electromagnetic flowmeter to measure the change in the flow rate of the magnetorheological fluid during the polishing process. By controlling the rotational speed of the liquid pump and realizing the coarse and fine two-stage regulation of the flow rate fluctuation of the magnetorheological fluid by controlling the output displacement of the actuator group, the height of the liquid pump, the position of the nozzle, and the rotational speed of the polishing wheel, the flow rate fluctuation of the magnetorheological fluid at each polishing point meets the requirements of high-precision polishing, ensuring the constancy of the removal function. The present invention does not require an additional follow-up device, has a lower equipment cost, a small flow rate change, and a more stable flow rate fluctuation of the magnetorheological fluid. Brief Description of the Drawings

[0027] Figure 1 FIG. is a schematic structural view of the magnetorheological polishing system based on electromagnetic flowmeter sensing according to an embodiment of the present invention from one perspective; Figure 2 FIG. is a schematic structural view of the magnetorheological polishing system based on electromagnetic flowmeter sensing according to an embodiment of the present invention from another perspective; Figure 3 FIG. is a schematic structural view of the actuator according to an embodiment of the present invention; Figure 4 FIG. is a schematic structural view of the supply device according to an embodiment of the present invention; Figure 5 FIG. is a schematic structural view of the nozzle adjusting seat according to an embodiment of the present invention.

[0028] Reference Numerals: polishing platform 1, element to be polished 101, test polishing element 102, industrial robot 201, magnetorheological mounting bracket 202, polishing wheel 203, magnet 204, nozzle 205, drive motor 206, driving pulley 207, driven pulley 208, synchronous belt 209, transition plate 210, cylinder block 211, chamber A 212, chamber B 213, oil scraping ring 214, connecting plate 215, moving piston 216, liquid pump 217, mounting bracket 218, mounting plate 219, linear guide 220, ball screw stepping motor 221, fixing bracket 222, nozzle adjusting motor 223, pushing plate 224, nozzle mounting bracket 225, arc guide 226, actuator group 227, electromagnetic flowmeter 3, laser tracker 4, target ball 401, computer 5. Detailed Embodiments

[0029] In the following, embodiments of the present invention will be described with reference to the drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, their detailed descriptions will not be repeated.

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and do not constitute a limitation to the present invention.

[0031] In a first aspect, the present embodiment provides a magnetorheological polishing system based on electromagnetic flowmeter sensing. The structure of the device is as Figures 1 - 5 shown and includes: A polishing platform 1, on which a component to be polished 101 and a test polishing component 102 are arranged; A polishing assembly, which includes an industrial robot 201 and a magnetorheological polishing module. The industrial robot 201 is used to drive the magnetorheological polishing module to move to the position where the test polishing component 102 is located or drive the magnetorheological polishing module to move to the position where the component to be polished 101 is located; the magnetorheological polishing module is used to polish the component to be polished 101 or the test polishing component 102; the magnetorheological polishing module includes a magnetorheological mounting frame 202, a polishing wheel 203, a magnet 204, a nozzle 205, an actuator group 227, a nozzle adjustment seat, a supply device and a polishing wheel driving device. One end of the actuator group 227 is connected to the magnetorheological mounting frame 202, and the other end of the actuator group 227 is connected to the tool end of the industrial robot 201. The actuator group 227 is used to adjust the polishing gap; the magnetorheological mounting frame 202 is mounted on the tool end of the industrial robot 201, and the polishing wheel driving device is mounted on the magnetorheological mounting frame 202 and is used to drive the polishing wheel 203 to rotate to polish the component to be polished 101 or the test polishing component 102; the nozzle 205 is mounted on the magnetorheological mounting frame 202 through the nozzle adjustment seat and is used to spray magnetorheological fluid onto the polishing wheel 203, and the nozzle adjustment seat is used to adjust the position of the nozzle 205; the supply device is arranged on one side of the polishing platform and is used to pump magnetorheological fluid into the nozzle 205; An electromagnetic flowmeter 3, which is arranged on the industrial robot 201 and is used to monitor the flow rate of the magnetorheological fluid at the liquid outlet of the nozzle 205; A laser tracker 4, which is arranged on one side of the polishing platform 1 and is used in cooperation with a target ball 401 to measure the vertical distance (hereinafter simply referred to as the vertical distance) between the nozzle 205 and the liquid pump 217; A computer 5 is configured to respectively establish a first conversion relationship between the vertical distance and the rotational speed of the liquid pump 217, a second conversion relationship between the polishing gap and the flow rate of the magnetorheological fluid monitored by the electromagnetic flowmeter, a third conversion relationship between the height of the liquid pump 217 and the flow rate of the magnetorheological fluid, a fourth conversion relationship between the position of the nozzle 205 and the flow rate of the magnetorheological fluid, and a fifth conversion relationship between the rotational speed of the polishing wheel 203 and the flow rate of the magnetorheological fluid, and adjust the rotational speed of the liquid pump 217, the output displacement of the actuator group 227, the height of the liquid pump 217, the position of the nozzle 205, and the rotational speed of the polishing wheel 203 according to the first to fifth conversion relationships to maintain a constant removal function at each polishing point of the element 101 to be polished; and the computer is configured to establish a sixth conversion relationship between the removal function and the flow rate of the magnetorheological fluid based on the flow rate of the magnetorheological fluid monitored by the electromagnetic flowmeter, and obtain a variable removal function set according to the sixth conversion relationship to perform secondary polishing on the element 101 to be polished.

[0032] The polishing wheel driving device includes a driving motor 206, a driving pulley 207, a driven pulley 208, and a timing belt 209. The driving motor 206 is installed on the magnetorheological mounting bracket 202. A bearing seat is installed on the magnetorheological mounting bracket 202, and a bearing is installed in the bearing seat. The bearing is connected to the polishing wheel 203. The driven pulley 208 is sleeved on the bearing, the driving pulley 207 is sleeved on the output end of the driving motor 206, and the timing belt 209 is tensioned between the driven pulley 208 and the driving pulley 207. The polishing wheel 203 is driven to rotate by the driving motor 206. For details, reference can be made to the Chinese patent with a publication date of July 12, 2024 and a publication number of CN118322074A.

[0033] The actuator group 227 is composed of two cascaded high-frequency actuators, that is, one high-frequency actuator is installed on the output end of the other high-frequency actuator, so that the total output displacement of the actuator group 227 is the sum of the output displacements of the two high-frequency actuators. In the embodiment of the present invention, the high-frequency actuator preferably adopts the SG model hydrostatic linear cylinder of Jilin Huakong Test Instrument Co., Ltd. The structures of the two high-frequency actuators are the same and both include a transition plate 210, a cylinder block 211, an A chamber 212, a B chamber 213, an oil scraper ring 214, a connecting plate 215, and a moving piston 216. The transition plate 210 is used to connect the tool end of the industrial robot 201 to the cylinder block 211. The A chamber 212 and the B chamber 213 are used to control the inflow and outflow of hydraulic oil. The oil scraper ring 214 is used to prevent the hydraulic oil from flowing out of the cylinder block 211. The moving piston 216 is used for position output. The connecting plate 215 is used to connect the moving piston 216 to the magnetorheological polishing module or another high-frequency actuator, and then output displacement to the magnetorheological polishing module or another high-frequency actuator.

[0034] The supply device includes a liquid pump 217, a mounting bracket 218, a mounting plate 219, a linear guide 220, and a ball screw stepper motor 221. Among them, the linear guide 220 and the ball screw stepper motor 221 are respectively vertically mounted on the mounting bracket 218, and the linear guide 220 is distributed on both sides of the ball screw stepper motor 221. The liquid pump 217 is mounted on the mounting plate 219. The mounting plate 219 is respectively connected to the slider of the linear guide 220 and the nut of the ball screw stepper motor 221. The height of the liquid pump 217 is adjusted by the ball screw stepper motor 221. The liquid pump 217 selects the CFLC vertical multi-stage pump of Shanghai Orient Pump Industry Co., Ltd.

[0035] The nozzle adjustment seat includes a fixing frame 222, a nozzle adjustment motor 223, a pushing plate 224, a nozzle mounting frame 225, and an arc guide 226. The fixing frame 222 is mounted on the magnetorheological mounting frame 202. The fixing frame 230 is an L-shaped structure. The nozzle adjustment motor 223 and the arc guide 226 are respectively mounted on two perpendicular parts of the fixing frame 222, and the length direction of the arc guide 226 is the telescopic direction of the nozzle adjustment motor 223. The pushing plate 224 is mounted on the output end of the nozzle adjustment motor 223. One end of the nozzle mounting frame 225 is respectively connected to the pushing plate 224 and the slider of the arc guide 226. The other end of the nozzle mounting frame 225 is used to mount the nozzle 205. The nozzle 205 is driven to move by the nozzle adjustment motor 223 to adjust the distance between the nozzle 205 and the polishing wheel 203.

[0036] It should be noted that there is a strong magnetic phenomenon in the working area where the magnetorheological polishing module is located. The connection of various circuits needs to avoid the working area to prevent the wires from being adsorbed to the magnetorheological polishing module and affecting the normal operation.

[0037] In the second aspect, the present embodiment also provides a magnetorheological polishing method for adjusting the polishing gap based on an actuator, which is realized by using the above-mentioned magnetorheological polishing system based on an electromagnetic flowmeter, and includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through the electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting. Among them, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, different polishing gaps are set, and the flow rates of the magnetorheological fluid corresponding to different polishing gaps at each vertical distance are measured by an electromagnetic flowmeter. Discrete data of the polishing gap and the magnetorheological fluid flow rate at each vertical distance are obtained. Through data fitting, a second conversion relationship between the polishing gap and the corresponding magnetorheological fluid flow rate at each vertical distance is obtained. The second conversion relationship can be expressed as , where represents the polishing gap at each vertical distance, represents the flow rate of the magnetorheological fluid corresponding to the polishing gap at each vertical distance, represents the conversion relationship between the polishing gap and the magnetorheological fluid flow rate at each vertical distance.

[0038] The purpose of step S1 is to establish a first conversion relationship between the vertical distance and the liquid pump speed and a second conversion relationship between the polishing gap and the corresponding magnetorheological fluid flow rate at each vertical distance by using an electromagnetic flowmeter, specifically as follows: Set the theoretical initial values of the liquid pump speed and the corresponding theoretical initial values of the magnetorheological fluid flow rate at each polishing point of the test polishing element. Set the vertical distance between the liquid pump and the nozzle at at least 10 different values. Measure the magnetorheological fluid flow rate corresponding to different vertical distances by an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value. Obtain the discrete data of the vertical distance and the liquid pump speed. Use the Polyfit instruction in Matlab (this instruction is a basic general instruction in the Matlab software) to perform data fitting to obtain the first conversion relationship; At each vertical distance, set the polishing gap at at least 10 different values. Measure the polishing gap and the corresponding magnetorheological fluid flow rate at different vertical distances by an electromagnetic flowmeter. Obtain the discrete data of the polishing gap and the corresponding magnetorheological fluid flow rate at each vertical distance. Use the Polyfit instruction in Matlab (this instruction is a basic general instruction in the Matlab software) to perform data fitting to obtain the second conversion relationship.

[0039] S2: According to the surface height change of the element to be polished, calculate the change of the liquid pump speed based on the first conversion relationship to obtain the theoretical liquid pump speed corresponding to each polishing point of the element to be polished. Polish the element to be polished according to the theoretical liquid pump speed of each polishing point. At the same time, monitor the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point in real time by an electromagnetic flowmeter and send it to the computer; where the theoretical liquid pump speed is expressed as , where represents the theoretical liquid pump speed of each polishing point, i = 1, 2, 3... m, and m represents the number of polishing points, Represents the vertical distance of the i-th polishing point.

[0040] The height variation of the curved surface of the element to be polished reflects the change in the vertical distance between the liquid pump and the nozzle. According to the height of each polishing point on the curved surface of the element to be polished, the theoretical liquid pump speed of each polishing point is calculated using the first conversion relationship, and the liquid pump speed is adjusted in real time according to the theoretical liquid pump speed of each polishing point to complete the rough adjustment of the magnetic rheological fluid flow rate change during the large-range height movement of the entire curved surface when polishing the element to be polished.

[0041] Since the magnetic rheological fluid measured by the electromagnetic flowmeter needs to be transported through the pipeline and driven by the polishing wheel to reach the working area of the polishing wheel, the magnetic rheological fluid of the current flow rate will reach the working area of the polishing wheel after a period of time. To ensure the adjustment of the removal function change at each polishing point, the dwell time of the polishing point needs to be set. The specific setting method is as follows: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot.

[0042] S220: Drive the industrial robot to move towards the experimental bench so that the lowest point of the polishing wheel just touches the experimental bench. Place the target ball of the laser tracker at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time.

[0043] S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , is the Z-axis coordinate measured by placing the target ball on the nozzle. The time required for the magnetic rheological fluid ejected by the magnetic rheological supply system to reach the lowest point of the polishing wheel is , where, represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetic rheological fluid, represents the radius of the polishing wheel.

[0044] When the computer generates the polishing control program, if the dwell time of each polishing point is satisfied, the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

[0045] S3: Set the allowable range of flow rate fluctuation in the computer, and determine whether the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set allowable range of flow rate fluctuation. If it does not exceed, keep the polishing gap of the polishing point unchanged. If it exceeds, control the output displacement of the actuator group, and then adjust the polishing gap until the actual flow rate of the magnetorheological fluid does not exceed the allowable range of flow rate fluctuation, so as to maintain the constant removal function of each polishing point.

[0046] Since the polishing of optical elements is a variable-speed movement of the polishing system, the movement speeds between two adjacent polishing points are often different. During the process from one polishing point to the next polishing point, there is often a situation where the theoretical polishing position does not match the actual polishing position, resulting in fluctuations in the flow rate of the magnetorheological fluid and changes in the removal function.

[0047] Therefore, it is necessary to set the allowable range of flow rate fluctuation of the magnetorheological fluid during the polishing process in the computer. , is the lower limit value of the flow rate fluctuation of the magnetorheological fluid, is the upper limit value of the flow rate fluctuation of the magnetorheological fluid.

[0048] During the polishing process, the actual flow rate value of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point is measured in real time by an electromagnetic flowmeter. If the measured actual flow rate value of the magnetorheological fluid is within range, the flow rate fluctuation of the magnetorheological fluid meets the requirements of high-precision polishing, and the measurement data does not need to be output for processing. If the measured actual flow rate value of the magnetorheological fluid is not within range, the flow rate fluctuation of the magnetorheological fluid does not meet the requirements of high-precision polishing, and the measurement data needs to be output to the computer for processing. The data processed by the computer is sent to the industrial robot, and finally, the output displacement of the actuator group is adjusted to control the change of the flow rate of the magnetorheological fluid to maintain the constant removal function.

[0049] To ensure polishing safety, it is necessary to set the maximum adjustment amount of the output displacement of the actuator group in the computer to be , place the element to be polished on the polishing platform and fix it, drive the polishing system to polish the element to be polished, and at the same time measure the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle by using an electromagnetic flowmeter. .

[0050] If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set allowable range of flow rate fluctuation , keep the polishing gap of the polishing point unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set allowable range of flow rate fluctuation and the adjustment amount of the output displacement of the current actuator group , then adjust the output displacement of the current actuator group according to the following formula : ; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow fluctuation tolerance range and the adjustment amount of the output displacement of the current actuator group , then adjust the output displacement of the current actuator group according to the following formula : ; wherein, represents the initial output displacement of the set actuator group

[0051] By adjusting the output displacement of the actuator group, the polishing gap between the polishing wheel and the element to be polished is changed, and the precise adjustment of the small-range change of the magnetorheological fluid flow rate is completed, so that the flow rate fluctuation of the magnetorheological fluid at each polishing point meets the high-precision polishing requirements, and the constancy of the removal function during the polishing process is ensured

[0052] Compared with the current mainstream real-time control scheme for the flow rate change of the magnetorheological fluid supply system based on the follow-up device, the present invention uses an electromagnetic flowmeter to measure the change of the flow rate during the polishing process of the polishing system and realizes the rough and fine two-stage adjustment of the flow rate fluctuation by controlling the liquid pump speed and the output displacement of the actuator group, so as to realize the real-time control of the change of the removal function. The present invention does not require an additional follow-up device, has a lower equipment cost, a small flow rate change, and a more stable magnetorheological fluid flow rate fluctuation

[0053] In a third aspect, the present embodiment further provides a magnetorheological polishing method based on the height adjustment of the liquid pump, which is realized by using the above-mentioned magnetorheological polishing system based on the electromagnetic flowmeter perception, and includes the following steps S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate at each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through the electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; wherein, the first conversion relationship is expressed as , represents the liquid pump speed represents the vertical distance represents the conversion relationship between the vertical distance and the liquid pump speed And at each vertical distance, different polishing gaps are set, and at each polishing gap, different liquid pump heights are set. The flow rate of the magnetorheological fluid corresponding to different liquid pump heights at each polishing gap is measured by an electromagnetic flowmeter, and discrete data of the liquid pump height and the magnetorheological fluid flow rate at each polishing gap are obtained. Through data fitting, a third conversion relationship between the liquid pump height and the corresponding magnetorheological fluid flow rate at each polishing gap is obtained. The third conversion relationship can be expressed as , where represents the liquid pump height at each polishing gap, represents the flow rate of the magnetorheological fluid corresponding to the liquid pump height at each polishing gap, represents the conversion relationship between the liquid pump height and the magnetorheological fluid flow rate at each polishing gap.

[0054] At different polishing gaps and vertical distances, by changing the liquid pump height, the removal function is made constant, and then various data are collected to obtain a complete third conversion relationship between the liquid pump at different heights and the corresponding magnetorheological fluid flow rate at each polishing gap, which is convenient for subsequent adjustment of various parameters.

[0055] The different polishing gaps mean that the relative distance between the polishing wheel and the magnet remains unchanged, and the distance between the entire magnetorheological polishing module and the test polishing element changes.

[0056] The purpose of step S1 is to establish a first conversion relationship between the vertical distance and the liquid pump speed and a third conversion relationship between the liquid pump height and the corresponding magnetorheological fluid flow rate at each polishing gap by using an electromagnetic flowmeter, as follows: Set the theoretical initial values of the liquid pump speed and the theoretical initial values of the corresponding magnetorheological fluid flow rate at each polishing point of the test polishing element. Set the vertical distance between the liquid pump and the nozzle at at least 10 different values. Measure the magnetorheological fluid flow rate corresponding to different vertical distances by an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, and obtain discrete data of the vertical distance and the liquid pump speed. Use the Polyfit instruction in Matlab (this instruction is a basic general instruction in the matlab software) to perform data fitting to obtain the first conversion relationship; At each polishing gap, set the liquid pump height at at least 10 different values. Measure the liquid pump height and the corresponding magnetorheological fluid flow rate at different polishing gaps by an electromagnetic flowmeter, and obtain discrete data of the liquid pump height and the corresponding magnetorheological fluid flow rate at each polishing gap. Use the Polyfit instruction in Matlab (this instruction is a basic general instruction in the matlab software) to perform data fitting to obtain the third conversion relationship.

[0057] S2: According to the height variation of the curved surface of the component to be polished, calculate the variation of the liquid pump rotation speed based on the first conversion relationship, obtain the theoretical liquid pump rotation speeds corresponding to each polishing point of the component to be polished, polish the component to be polished according to the theoretical liquid pump rotation speeds of each polishing point, and simultaneously monitor the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point in real time through an electromagnetic flowmeter and send it to the computer; where the theoretical liquid pump rotation speed is expressed as , where represents the theoretical liquid pump rotation speeds of each polishing point, i = 1, 2, 3... m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point.

[0058] The height variation of the curved surface of the component to be polished reflects the variation of the vertical distance between the liquid pump and the nozzle. According to the heights of each polishing point on the curved surface of the component to be polished, calculate the theoretical liquid pump rotation speeds of each polishing point using the first conversion relationship, and adjust the liquid pump rotation speed in real time according to the theoretical liquid pump rotation speeds of each polishing point to complete the rough adjustment of the magnetorheological fluid flow rate variation during the large-range height movement of the entire curved surface when the polishing system polishes the component to be polished.

[0059] Since the magnetorheological fluid measured by the electromagnetic flowmeter needs to be transported through the pipeline and driven by the polishing wheel to reach the working area of the polishing wheel, the current flow of the magnetorheological fluid will reach the working area of the polishing wheel after a period of time. In order to ensure the adjustment of the removal function variation at each polishing point, the residence time of the polishing point needs to be set. The specific setting method is as follows: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot.

[0060] S220: Drive the industrial robot to move towards the experimental bench so that the lowest point of the polishing wheel just touches the experimental bench, place the target ball of the laser tracker at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time.

[0061] S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the pipeline length between the electromagnetic flowmeter and the nozzle, represents the flow velocity of the magnetorheological fluid, represents the radius of the polishing wheel.

[0062] When the computer generates the polishing control program, if the residence time of each polishing point When the generated polishing control program is appropriate; if there is a dwell time at a certain polishing point , then extend the dwell time of this polishing point , regenerate the polishing control program so that the dwell time of each polishing point .

[0063] S3: Set the allowable tolerance range of flow rate fluctuation in the computer, and judge whether the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set allowable tolerance range of flow rate fluctuation. If it does not exceed, keep the height of the liquid pump at the polishing point unchanged. If it exceeds, control the ball screw stepper motor to adjust the height of the liquid pump at the polishing point until the actual magnetorheological fluid flow rate does not exceed the allowable tolerance range of flow rate fluctuation, so as to maintain the constant removal function of each polishing point.

[0064] Since the polishing of optical elements is a variable-speed movement of the polishing system, the movement speeds between two adjacent polishing points are often not the same. During the process from one polishing point to the next polishing point, there is often a situation where the theoretical polishing position does not match the actual polishing position, the magnetorheological fluid flow rate fluctuates, and the removal function changes.

[0065] Therefore, it is necessary to set the allowable tolerance range of magnetorheological fluid flow rate fluctuation during the polishing process in the computer , is the lower limit value of the magnetorheological fluid flow rate fluctuation, is the upper limit value of the magnetorheological fluid flow rate fluctuation.

[0066] During the polishing process, the actual magnetorheological fluid flow rate value at the liquid outlet of the nozzle corresponding to each polishing point is measured in real time by an electromagnetic flowmeter. If the measured actual magnetorheological fluid flow rate value is within the measurement data does not need to be output and processed. If the measured actual magnetorheological fluid flow rate value is not within the range, then the magnetorheological fluid flow rate fluctuation does not meet the high-precision polishing requirements, and the measurement data needs to be output to the computer for processing. The data processed by the computer is sent to the industrial ball screw stepper motor, and finally the magnetorheological fluid flow rate change is regulated by adjusting the height of the liquid pump to maintain the constant removal function.

[0067] To ensure polishing safety, it is necessary to set the maximum adjustment amount of the liquid pump height in the computer to be , place the element to be polished on the polishing platform and fix it, drive the polishing system to polish the element to be polished, and at the same time measure the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle by using an electromagnetic flowmeter .

[0068] If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point Within the set flow fluctuation tolerance range [FL1, FL2], keep the height of the liquid pump at the polishing point unchanged; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is within the set flow fluctuation tolerance range keep the height of the liquid pump at the polishing point unchanged; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow fluctuation tolerance range and the current liquid pump height adjustment amount then adjust the current liquid pump height according to the following formula : ; If the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow fluctuation tolerance range and the current liquid pump height adjustment amount then adjust the current liquid pump height according to the following formula : ; wherein, represents the initial height of the set liquid pump.

[0069] By adjusting the height of the liquid pump, precise adjustment of small-range changes in the magnetorheological fluid flow rate is completed, so that the flow rate fluctuation of the magnetorheological fluid at each polishing point meets the high-precision polishing requirements, ensuring the constancy of the removal function during the polishing process.

[0070] Compared with the current mainstream real-time control scheme for flow rate changes in magnetorheological fluid supply systems based on follow-up devices, the present invention uses an electromagnetic flowmeter to measure the flow rate changes during the polishing process of the polishing system and realizes coarse and fine two-stage regulation of flow rate fluctuations by controlling the rotational speed of the liquid pump and the height of the liquid pump, thereby realizing real-time control of changes in the removal function. The present invention does not require an additional follow-up device, has lower equipment costs, smaller flow rate changes, and more stable magnetorheological fluid flow rate fluctuations.

[0071] In a fourth aspect, the present embodiment also provides a magnetorheological polishing method based on nozzle position adjustment, which is realized by using the above-mentioned magnetorheological polishing system sensed by an electromagnetic flowmeter, and includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element. Polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; where the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, set different polishing gaps, set different nozzle positions at each polishing gap, measure the magnetorheological fluid flow rate corresponding to different nozzle positions at each polishing gap through an electromagnetic flowmeter, obtain the discrete data of the nozzle position and the magnetorheological fluid flow rate at each polishing gap, and obtain the fourth conversion relationship between the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap through data fitting. The fourth conversion relationship can be expressed as , where represents the nozzle position at each polishing gap, represents the magnetorheological fluid flow rate corresponding to the nozzle position at each polishing gap, represents the conversion relationship between the nozzle position and the magnetorheological fluid flow rate at each polishing gap.

[0072] At different polishing gaps and vertical distances, by changing the nozzle position, make the removal function constant, and then collect each data to obtain the complete fourth conversion relationship between the nozzle at different positions and the corresponding magnetorheological fluid flow rate at each polishing gap, which is convenient for subsequent parameter regulation.

[0073] Different polishing gaps mean that the relative distance between the polishing wheel and the magnet remains unchanged, and the distance between the entire magnetorheological polishing module and the test polishing element changes.

[0074] The purpose of step S1 is to establish the first conversion relationship between the vertical distance and the liquid pump speed and the fourth conversion relationship between the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap by using an electromagnetic flowmeter, specifically as follows: Set the theoretical initial values of the liquid pump rotation speed and the corresponding theoretical initial values of the magnetorheological fluid flow rate for each polishing point of the test polishing element. Set the vertical distance between the liquid pump and the nozzle at at least 10 different values. Measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump rotation speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, and obtain the discrete data of the vertical distance and the liquid pump rotation speed. Use the Polyfit instruction of Matlab (this instruction is a basic general instruction of the Matlab software) to perform data fitting to obtain the first conversion relationship; At each polishing gap, set the nozzle position at at least 10 different values. Measure the nozzle position and the corresponding magnetorheological fluid flow rate at different polishing gaps through an electromagnetic flowmeter, and obtain the discrete data of the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap. Use the Polyfit instruction of Matlab (this instruction is a basic general instruction of the Matlab software) to perform data fitting to obtain the fourth conversion relationship.

[0075] S2: According to the surface height change of the element to be polished, calculate the change of the liquid pump rotation speed based on the first conversion relationship to obtain the theoretical liquid pump rotation speed corresponding to each polishing point of the element to be polished. Polish the element to be polished according to the theoretical liquid pump rotation speed of each polishing point. At the same time, the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point is monitored in real time through an electromagnetic flowmeter and sent to the computer; among them, the theoretical liquid pump rotation speed is expressed as , where represents the theoretical liquid pump rotation speed of each polishing point, i = 1, 2, 3…m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point.

[0076] The surface height change of the element to be polished reflects the change of the vertical distance between the liquid pump and the nozzle. According to the height of each polishing point on the surface of the element to be polished, use the first conversion relationship to calculate the theoretical liquid pump rotation speed of each polishing point, and perform real-time adjustment of the liquid pump rotation speed according to the theoretical liquid pump rotation speed of each polishing point to complete the rough adjustment of the magnetorheological fluid flow rate change during the large-range high and low movement of the entire surface when the polishing system polishes the element to be polished.

[0077] Since the magnetorheological fluid measured by the electromagnetic flowmeter needs to be transported through pipelines and driven by the polishing wheel to reach the working area of the polishing wheel, the current flow of the magnetorheological fluid will reach the working area of the polishing wheel after a period of time. In order to ensure the adjustment of the removal function change at each polishing point, it is necessary to set the dwell time of the polishing point. The specific setting method is as follows: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot.

[0078] S220: Drive the industrial robot to move towards the test bench so that the lowest point of the polishing wheel just touches the test bench. Place the target ball of the laser tracker at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time.

[0079] S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

[0080] When the computer generates the polishing control program, if the dwell time of each polishing point , then the generated polishing control program is appropriate; if there is a dwell time for a certain polishing point, then extend the dwell time of this polishing point, and regenerate the polishing control program so that the dwell time

[0081] of each polishing point

[0082] Since the polishing of optical elements is a variable-speed movement of the polishing system, the movement speeds between two adjacent polishing points are often not the same. During the process from one polishing point to the next polishing point, there is often a situation where the theoretical polishing position does not match the actual polishing position, the flow rate of the magnetorheological fluid fluctuates, and the removal function changes.

[0083] Therefore, it is necessary to set the allowable tolerance range of the magnetorheological fluid flow rate during the polishing process in the computer , is the lower limit value of the magnetorheological fluid flow rate fluctuation, is the upper limit value of the magnetorheological fluid flow rate fluctuation.

[0084] During the polishing process, the actual flow rate value of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point is measured in real time by an electromagnetic flowmeter. If the measured actual flow rate value of the magnetorheological fluid is within the range, the fluctuation of the magnetorheological fluid flow rate meets the requirements of high-precision polishing, and the measurement data does not need to be output for processing. If the measured actual flow rate value of the magnetorheological fluid is not within the range, the fluctuation of the magnetorheological fluid flow rate does not meet the requirements of high-precision polishing, and the measurement data needs to be output to a computer for processing. The data processed by the computer is sent to an industrial nozzle adjustment motor, and finally, the position of the nozzle is adjusted to control the change in the flow rate of the magnetorheological fluid to maintain a constant removal function.

[0085] To ensure polishing safety, the maximum adjustment amount of the nozzle position needs to be set in the computer to , place the component to be polished on the polishing platform and fix it, drive the polishing system to polish the component to be polished, and at the same time use an electromagnetic flowmeter to measure the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle .

[0086] If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set flow rate fluctuation tolerance range , keep the nozzle position at the polishing point unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current nozzle position adjustment amount is less than, then adjust the current nozzle position according to the following formula : ; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current nozzle position adjustment amount is greater than, then adjust the current nozzle position according to the following formula : ; where represents the set initial position of the nozzle.

[0087] By adjusting the nozzle position, the precise adjustment of the small-range change in the flow rate of the magnetorheological fluid is completed, so that the flow rate fluctuation of the magnetorheological fluid at each polishing point meets the requirements of high-precision polishing, and the constancy of the removal function during the polishing process is ensured.

[0088] Compared with the current mainstream real-time control scheme for the flow rate change of the magnetorheological fluid supply system based on a follow-up device, the present invention uses an electromagnetic flowmeter to measure the flow rate change during the polishing process of the polishing system and realizes the rough and fine two-stage regulation of the flow rate fluctuation by controlling the rotational speed of the liquid pump and the position of the nozzle, so as to realize the real-time control of the change of the removal function. The present invention does not require an additional follow-up device, has a lower equipment cost, a small flow rate change, and a more stable flow rate fluctuation of the magnetorheological fluid.

[0089] In a fifth aspect, the present embodiment further provides a magnetorheological polishing method based on the regulation of the polishing wheel rotational speed, which is realized by using the above-mentioned magnetorheological polishing system sensed by the electromagnetic flowmeter, and includes the following steps: S1: Set the theoretical initial values of the rotational speed of the liquid pump and the corresponding magnetorheological fluid flow rate at each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through the electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the rotational speed of the liquid pump so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the rotational speed of the liquid pump, and obtain the first conversion relationship between the vertical distance and the rotational speed of the liquid pump through data fitting; wherein, the first conversion relationship is expressed as , represents the rotational speed of the liquid pump, represents the vertical distance, represents the conversion relationship between the vertical distance and the rotational speed of the liquid pump; And at each vertical distance, set different polishing gaps, set different polishing wheel rotational speeds at each polishing gap, measure the magnetorheological fluid flow rate corresponding to different polishing wheel rotational speeds at each polishing gap through the electromagnetic flowmeter, obtain the discrete data of the polishing wheel rotational speed and the magnetorheological fluid flow rate at each polishing gap, and obtain the fifth conversion relationship between the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap through data fitting. The fifth conversion relationship can be expressed as , where represents the polishing wheel rotational speed at each polishing gap, represents the magnetorheological fluid flow rate corresponding to the polishing wheel rotational speed at each polishing gap, represents the conversion relationship between the polishing wheel rotational speed and the magnetorheological fluid flow rate at each polishing gap.

[0090] At different polishing gaps and vertical distances, by changing the polishing wheel rotational speed, make the removal function constant, and then collect each data to obtain the complete fifth conversion relationship between the polishing wheel rotational speed and the corresponding magnetorheological fluid flow rate at each polishing gap, which is convenient for subsequent parameter regulation.

[0091] The different polishing clearances refer to the situation where the relative distance between the polishing wheel and the magnet remains unchanged, while the distance between the entire magnetorheological polishing module and the test polishing element changes.

[0092] The purpose of step S1 is to establish a first conversion relationship between the vertical distance and the liquid pump speed, as well as a fifth conversion relationship between the polishing wheel speed and the corresponding magnetorheological fluid flow rate under each polishing clearance, specifically as follows: Set the theoretical initial values of the liquid pump speed and the corresponding theoretical initial values of the magnetorheological fluid flow rate for each polishing point of the test polishing element. Set the vertical distance between the liquid pump and the nozzle at at least 10 different values. Measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtaining discrete data of the vertical distance and the liquid pump speed. Use the Polyfit instruction in Matlab (this instruction is a basic general instruction in the Matlab software) to perform data fitting to obtain the first conversion relationship; Under each polishing clearance, set the polishing wheel speed at at least 10 different values. Measure the polishing wheel speed and the corresponding magnetorheological fluid flow rate under different polishing clearances through an electromagnetic flowmeter, obtaining discrete data of the polishing wheel speed and the corresponding magnetorheological fluid flow rate under each polishing clearance. Use the Polyfit instruction in Matlab (this instruction is a basic general instruction in the Matlab software) to perform data fitting to obtain the fifth conversion relationship.

[0093] S2: According to the surface height change of the element to be polished, calculate the change in the liquid pump speed based on the first conversion relationship to obtain the theoretical liquid pump speed corresponding to each polishing point of the element to be polished. Polish the element to be polished according to the theoretical liquid pump speed of each polishing point. At the same time, monitor the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point in real time through an electromagnetic flowmeter and send it to the computer; where the theoretical liquid pump speed is expressed as where, represents the theoretical liquid pump speed of each polishing point, i = 1, 2, 3…m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point.

[0094] The surface height change of the element to be polished reflects the change in the vertical distance between the liquid pump and the nozzle. According to the height of each polishing point on the surface of the element to be polished, calculate the theoretical liquid pump speed of each polishing point using the first conversion relationship, and perform real-time adjustment of the liquid pump speed according to the theoretical liquid pump speed of each polishing point to complete the rough adjustment of the magnetorheological fluid flow rate change during the large-range height movement of the entire surface when polishing the element to be polished by the polishing system.

[0095] Since the magnetorheological fluid measured by the electromagnetic flowmeter needs to be transported through the pipeline and driven by the polishing wheel to reach the working area of the polishing wheel, the magnetorheological fluid of the current flow rate will reach the working area of the polishing wheel after a period of time. In order to ensure the adjustment of the removal function change at each polishing point, the residence time of the polishing point needs to be set. The specific setting method is as follows: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot.

[0096] S220: Drive the industrial robot to move towards the test bench so that the lowest point of the polishing wheel just touches the test bench. Place the target ball of the laser tracker at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time.

[0097] S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

[0098] When the polishing control program is generated by the computer, if the residence time of each polishing point, the generated polishing control program is appropriate; if there is a residence time for a certain polishing point, then extend the residence time of this polishing point, and regenerate the polishing control program so that the residence time of each polishing point.

[0099] S3: Set the flow fluctuation tolerance range in the computer, and judge whether the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set flow fluctuation tolerance range. If it does not exceed, keep the polishing wheel speed of the polishing point unchanged. If it exceeds, control the drive motor to adjust the polishing wheel speed of the polishing point until the actual magnetorheological fluid flow rate does not exceed the flow fluctuation tolerance range to maintain the constant removal function of each polishing point.

[0100] Since the polishing of optical elements is a variable-speed motion of the polishing system, the motion speeds between two adjacent polishing points are often different, and there is often a mismatch between the theoretical polishing position and the actual polishing position during the process from one polishing point to the next polishing point, resulting in fluctuations in the magnetorheological fluid flow rate and changes in the removal function.

[0101] Therefore, it is necessary to set the allowable tolerance range of the flow rate fluctuation of the magnetorheological fluid during the polishing process in the computer. , is the lower limit value of the flow rate fluctuation of the magnetorheological fluid, is the upper limit value of the flow rate fluctuation of the magnetorheological fluid.

[0102] During the polishing process, the actual flow rate value of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point is measured in real time by an electromagnetic flowmeter. If the measured actual flow rate value of the magnetorheological fluid is within the range, the flow rate fluctuation of the magnetorheological fluid meets the requirements of high-precision polishing, and the measurement data does not need to be output for processing. If the measured actual flow rate value of the magnetorheological fluid is not within the range, the flow rate fluctuation of the magnetorheological fluid does not meet the requirements of high-precision polishing, and the measurement data needs to be output to the computer for processing. The data processed by the computer is sent to the industrial robot, and finally, the flow rate change of the magnetorheological fluid is regulated by adjusting the polishing wheel speed to maintain the removal function constant.

[0103] To ensure polishing safety, it is necessary to set the maximum adjustment amount of the polishing wheel speed in the computer as . Place the component to be polished on the polishing platform and fix it. Drive the polishing system to polish the component to be polished, and at the same time, use an electromagnetic flowmeter to measure the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle. .

[0104] If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set allowable tolerance range of the flow rate fluctuation , keep the polishing wheel speed at the current polishing point unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set allowable tolerance range of the flow rate fluctuation and the current adjustment amount of the polishing wheel speed is, then adjust the current polishing wheel speed according to the following formula : ; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set allowable tolerance range of the flow rate fluctuation and the current adjustment amount of the polishing wheel speed is, then adjust the current polishing wheel speed according to the following formula : ; Among them, represents the initial speed of the polishing wheel.

[0105] By adjusting the rotation speed of the polishing wheel, precise adjustment of a small range of changes in the flow rate of the magnetorheological fluid is completed, so that the flow rate fluctuation of the magnetorheological fluid at each polishing point meets the requirements of high-precision polishing, and the constancy of the removal function during the polishing process is ensured.

[0106] Compared with the current mainstream real-time control scheme for the flow rate change of the magnetorheological fluid supply system based on a follow-up device, the present invention uses an electromagnetic flowmeter to measure the change in the flow rate during the polishing process of the polishing system and realizes two-stage coarse and fine adjustment of the flow rate fluctuation by controlling the rotation speed of the liquid pump and the rotation speed of the polishing wheel, thereby realizing the real-time control of the change in the removal function. The present invention does not require an additional follow-up device, has a lower equipment cost, a small flow rate change, and a more stable flow rate fluctuation of the magnetorheological fluid.

[0107] In a sixth aspect, the present embodiment further provides a magnetorheological polishing method based on the adjustment of the removal function, which is realized by using the above-mentioned magnetorheological polishing system based on the perception of the electromagnetic flowmeter, and includes the following steps: S1: Set the theoretical initial value of the magnetorheological fluid flow rate at each polishing point of the test polishing element, polish the test polishing element according to the theoretical initial value of the magnetorheological fluid flow rate to obtain the removal function, and at the same time measure the theoretical magnetorheological fluid flow rate corresponding to each polishing point of the test polishing element through the electromagnetic flowmeter, and calculate the sixth conversion relationship between the removal function and the theoretical magnetorheological fluid flow rate, where the sixth conversion relationship is expressed as , represents the removal function, represents the theoretical magnetorheological fluid flow rate at each polishing point of the test polishing element, represents the sixth conversion relationship between the theoretical magnetorheological fluid flow rate at each polishing point of the test polishing element and the removal function.

[0108] S2: Set the flow rate fluctuation tolerance range in the computer, polish the element to be polished for the first time according to the theoretical magnetorheological fluid flow rate, measure the actual magnetorheological fluid flow rate at the nozzle liquid outlet corresponding to each polishing point of the element to be polished through the electromagnetic flowmeter, and judge whether it exceeds the set flow rate fluctuation tolerance range. If it exceeds, record the actual magnetorheological fluid flow rate at the polishing point. After the element to be polished is polished for the first time, calculate the removal function corresponding to the actual magnetorheological fluid flow rate at each recorded polishing point based on the sixth conversion relationship to obtain a variable removal function set.

[0109] S3: Polish the element to be polished for the second time according to the variable removal function set, and determine the polishing amount at each polishing point when polishing the element to be polished for the second time through the variable removal function set.

[0110] After the element to be polished is processed for the first time, a variable removal function set is obtained , when the element to be polished is processed for the second time, with the variable removal function set Generate a machining control program as a machining parameter to complete secondary machining.

[0111] Combine the variable removal function set to perform secondary machining on the conductive element to be polished, meeting the requirements of high-precision magnetorheological machining. This process does not require an additional follow-up device, has lower equipment costs, a small flow change, and a more stable fluctuation in the magnetorheological fluid flow.

[0112] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. 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 imposed herein.

[0113] The above specific embodiments do not constitute a limitation on 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 principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A magnetorheological polishing system based on the sensing of an electromagnetic flowmeter, characterized in that, Including: A polishing platform, on which a component to be polished and a test polishing component are arranged; A polishing assembly, including an industrial robot and a magnetorheological polishing module. The industrial robot is used to drive the magnetorheological polishing module to move to the position where the test polishing component is located or the position where the component to be polished is located. The magnetorheological polishing module is used to polish the component to be polished or the test polishing component. The magnetorheological polishing module includes a magnetorheological mounting frame, a polishing wheel, a nozzle, a magnet, an actuator group and a supply device. One end of the actuator group is connected to the magnetorheological mounting frame, and the other end of the actuator group is connected to the tool end of the industrial robot. The polishing wheel and the magnet are respectively mounted on the magnetorheological mounting frame. The nozzle is mounted on the magnetorheological mounting frame through a nozzle adjusting seat. The nozzle adjusting seat is used to adjust the position of the nozzle. The nozzle is used to spray magnetorheological fluid onto the polishing wheel. The magnet is used to change the stiffness of the magnetorheological fluid. The polishing wheel is used to polish the test polishing component or the component to be polished. The supply device is arranged on one side of the polishing platform and is used to pump magnetorheological fluid into the nozzle; An electromagnetic flowmeter, arranged on the industrial robot, for monitoring the flow rate of the magnetorheological fluid at the liquid outlet of the nozzle; A laser tracker, arranged on one side of the polishing platform, used in cooperation with a target ball to measure the vertical distance between the nozzle and the liquid pump; A computer, used to respectively establish a first conversion relationship between the vertical distance and the rotational speed of the liquid pump, a second conversion relationship between the polishing gap and the flow rate of the magnetorheological fluid, a third conversion relationship between the height of the liquid pump and the flow rate of the magnetorheological fluid, a fourth conversion relationship between the nozzle position and the flow rate of the magnetorheological fluid, and a fifth conversion relationship between the rotational speed of the polishing wheel and the flow rate of the magnetorheological fluid according to the flow rate of the magnetorheological fluid monitored by the electromagnetic flowmeter, and adjust the rotational speed of the liquid pump, the output displacement of the actuator group, the height of the liquid pump, the nozzle position, and the rotational speed of the polishing wheel according to the first conversion relationship to the fifth conversion relationship to maintain the removal function of each polishing point of the component to be polished constant; And the computer is used to establish a sixth conversion relationship between the removal function and the flow rate of the magnetorheological fluid according to the flow rate of the magnetorheological fluid monitored by the electromagnetic flowmeter, and obtain a variable removal function set according to the sixth conversion relationship to perform secondary polishing on the component to be polished.

2. The magnetorheological polishing system based on electromagnetic flowmeter sensing according to claim 1, characterized in that, The supply device includes a liquid pump, a mounting bracket, a mounting plate, a linear guide rail and a ball screw stepping motor. Among them, the linear guide rail and the ball screw stepping motor are respectively vertically mounted on the mounting bracket, and the linear guide rails are distributed on both sides of the ball screw stepping motor. The liquid pump is mounted on the mounting plate, and the mounting plate is respectively connected to the slider of the linear guide rail and the nut of the ball screw stepping motor.

3. The magnetorheological polishing system based on electromagnetic flowmeter sensing according to claim 1, wherein The nozzle is mounted on the magnetorheological mounting frame through a nozzle adjusting seat, and the position of the nozzle relative to the polishing wheel is adjusted through the nozzle adjusting seat. The nozzle adjusting seat includes a fixed frame, a nozzle adjusting motor, a push plate, a nozzle mounting frame and an arc guide rail. Among them, the fixed frame is mounted on the magnetorheological mounting frame, the nozzle adjusting motor and the arc guide rail are respectively mounted on the fixed frame, the push plate is mounted on the output end of the nozzle adjusting motor, the nozzle mounting frame is respectively connected to the push plate and the slider of the arc guide rail, and the nozzle is mounted on the nozzle mounting frame.

4. The magnetorheological polishing system based on electromagnetic flowmeter sensing according to claim 1, characterized in that The magnetorheological polishing module further includes a polishing wheel driving device, which includes a driving motor, a motor connecting plate, a driving wheel, a driven wheel and a synchronous belt. The driving motor is installed on the connecting plate. A bearing seat is installed on the connecting plate, and a bearing is installed in the bearing seat. The bearing is connected to the polishing wheel. The driven wheel is sleeved on the bearing, and the driving wheel is sleeved on the output end of the driving motor. The synchronous belt is tensioned between the driven wheel and the driving wheel.

5. A magnetorheological polishing method for adjusting the polishing gap based on an actuator, which is realized by using the magnetorheological polishing system sensed based on an electromagnetic flowmeter as described in claim 1, and is characterized in that It includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element. Polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; among them, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, different polishing gaps are set, and the flow rate of the magnetorheological fluid corresponding to different polishing gaps at each vertical distance is measured by an electromagnetic flowmeter, discrete data of the polishing gap and the magnetorheological fluid flow rate at each vertical distance are obtained, and a second conversion relationship between the polishing gap and the corresponding magnetorheological fluid flow rate at each vertical distance is obtained by data fitting. The second conversion relationship can be expressed as , where represents the polishing gap at each vertical distance, represents the flow rate of the magnetorheological fluid corresponding to the polishing gap at each vertical distance, represents the conversion relationship between the polishing gap and the magnetorheological fluid flow rate at each vertical distance; S2: According to the height change of the curved surface of the element to be polished, calculate the change in the rotational speed of the liquid pump based on the first conversion relationship, obtain the theoretical rotational speed of the liquid pump corresponding to each polishing point of the element to be polished, polish the element to be polished according to the theoretical rotational speed of each polishing point, and at the same time, monitor the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point in real time through an electromagnetic flowmeter and send it to the computer; where the theoretical rotational speed of the liquid pump is expressed as , where represents the theoretical rotational speed of the liquid pump at each polishing point, i = 1, 2, 3... m, and m represents the number of polishing points, represents the vertical distance of the i-th polishing point; S3: Set the flow fluctuation tolerance range in the computer, and judge whether the actual magnetorheological fluid flow at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set flow fluctuation tolerance range. If it does not exceed, keep the polishing gap of the polishing point unchanged. If it exceeds, control the output displacement of the actuator group, and then adjust the polishing gap until the actual magnetorheological fluid flow does not exceed the flow fluctuation tolerance range to maintain the removal function of each polishing point constant.

6. The magnetorheological polishing method for adjusting the polishing gap based on an actuator according to claim 5, characterized in that, When polishing each polishing point of the element to be polished, a dwell time is set for each polishing point, which specifically includes the following steps: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform. Place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time. , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

7. The magnetorheological polishing method for adjusting the polishing gap based on an actuator according to claim 6, characterized in that When the computer generates a polishing control program, if the dwell time of each polishing point is met, the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

8. The magnetorheological polishing method for adjusting the polishing gap based on an actuator according to claim 5, characterized in that In step S3, the maximum adjustment amount of the output displacement of the actuator group is set in the computer to be ; And, If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set allowable tolerance range of the flow rate fluctuation the polishing gap at the polishing point remains unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the adjustment amount of the output displacement of the current actuator group , then adjust the output displacement of the current actuator group according to the following formula : ； If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the adjustment amount of the output displacement of the current actuator group , then adjust the output displacement of the current actuator group according to the following formula : ； Among them, represents the initial output displacement of the actuator group.

9. A magnetorheological polishing method based on the height adjustment of a liquid pump, which is realized by using the magnetorheological polishing system based on electromagnetic flowmeter sensing described in claim 2, and is characterized in that, It includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; among them, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, different polishing clearances are set, and at each polishing clearance, different liquid pump heights are set. The flow rate of the magnetorheological fluid corresponding to different liquid pump heights at each polishing clearance is measured by an electromagnetic flowmeter, and discrete data of the liquid pump height and the magnetorheological fluid flow rate at each polishing clearance are obtained. Through data fitting, a third conversion relationship between the liquid pump height and the corresponding magnetorheological fluid flow rate at each polishing clearance is obtained. The third conversion relationship can be expressed as , where represents the liquid pump height at each polishing clearance, represents the flow rate of the magnetorheological fluid corresponding to the liquid pump height at each polishing clearance, represents the conversion relationship between the liquid pump height and the magnetorheological fluid flow rate at each polishing clearance; S2: According to the height change of the curved surface of the element to be polished, calculate the change in the liquid pump speed based on the first conversion relationship to obtain the theoretical liquid pump speeds corresponding to each polishing point of the element to be polished. Polish the element to be polished according to the theoretical liquid pump speeds of each polishing point. At the same time, use an electromagnetic flowmeter to monitor the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point in real time and send it to the computer. The theoretical liquid pump speed is expressed as , where represents the theoretical liquid pump speeds of each polishing point, i = 1, 2, 3... m, and m represents the number of polishing points, represents the vertical distance of the i-th polishing point; S3: Set the flow fluctuation tolerance range in the computer, and judge whether the actual magnetorheological fluid flow at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set flow fluctuation tolerance range. If it does not exceed, keep the height of the liquid pump at the polishing point unchanged. If it exceeds, control the ball screw stepping motor to adjust the height of the liquid pump at the polishing point until the actual magnetorheological fluid flow does not exceed the flow fluctuation tolerance range to maintain the removal function of each polishing point constant.

10. The magnetorheological polishing method based on the height adjustment of the liquid pump according to claim 9, wherein, When polishing each polishing point of the element to be polished, a dwell time is set for each polishing point, which specifically includes the following steps: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform. Place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time. , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

11. The magnetorheological polishing method based on the height adjustment of a liquid pump according to claim 10, wherein, When the computer generates a polishing control program, if the dwell time of each polishing point is as such, the generated polishing control program is appropriate; if there exists a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

12. The magnetorheological polishing method based on the height adjustment of a liquid pump according to claim 9, wherein, In step S3, the maximum adjustment amount of the liquid pump height is set in the computer to be ; And, If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set allowable range of flow rate fluctuation keep the height of the liquid pump at the polishing point unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current liquid pump height adjustment amount is [value], then adjust the current liquid pump height according to the following formula : ； If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current liquid pump height adjustment amount is [value], then adjust the current liquid pump height according to the following formula : ； Among them, represents the initial height of the liquid pump.

13. A magnetorheological polishing method based on nozzle position adjustment, which is realized by using the magnetorheological polishing system sensed by an electromagnetic flowmeter according to claim 3, characterized in that, It includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; among them, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, different polishing gaps are set, different nozzle positions are set at each polishing gap, the flow rate of the magnetorheological fluid corresponding to different nozzle positions at each polishing gap is measured by an electromagnetic flowmeter, discrete data of the nozzle position and the magnetorheological fluid flow rate at each polishing gap are obtained, and a fourth conversion relationship between the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap is obtained through data fitting. The fourth conversion relationship can be expressed as , where represents the nozzle position at each polishing gap, represents the flow rate of the magnetorheological fluid corresponding to the nozzle position at each polishing gap, represents the conversion relationship between the nozzle position and the magnetorheological fluid flow rate at each polishing gap; S2: According to the height change of the curved surface of the element to be polished, calculate the change in the rotational speed of the liquid pump based on the first conversion relationship, obtain the theoretical rotational speed of the liquid pump corresponding to each polishing point of the element to be polished, polish the element to be polished according to the theoretical rotational speed of each polishing point, and simultaneously monitor the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point in real time through an electromagnetic flowmeter and send it to the computer; wherein, the theoretical rotational speed of the liquid pump is expressed as , where represents the theoretical rotational speed of the liquid pump at each polishing point, i = 1, 2, 3... m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point; S3: Set the flow fluctuation tolerance range in the computer, and judge whether the actual magnetorheological fluid flow at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set flow fluctuation tolerance range. If it does not exceed, keep the nozzle position of the polishing point unchanged. If it exceeds, control the nozzle adjustment motor to adjust the nozzle position of the polishing point until the actual magnetorheological fluid flow does not exceed the flow fluctuation tolerance range to maintain the removal function of each polishing point constant.

14. The magnetorheological polishing method based on nozzle position adjustment according to claim 13, wherein When polishing each polishing point of the element to be polished, a dwell time is set for each polishing point, which specifically includes the following steps: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform. Place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time. , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

15. The magnetorheological polishing method based on nozzle position adjustment according to claim 14, wherein, When the computer generates a polishing control program, if the dwell time of each polishing point is as follows, the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

16. The magnetorheological polishing method based on nozzle position adjustment according to claim 13, characterized in that, In step S3, the maximum adjustment amount of the nozzle position is set in the computer to be ; And, If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set allowable range of flow rate fluctuation keep the nozzle position of the polishing point unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current nozzle position adjustment amount is [value], then adjust the current nozzle position according to the following formula : ； If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current nozzle position adjustment amount is [value], then adjust the current nozzle position according to the following formula : ； Among them, represents the initial position of the nozzle.

17. A magnetorheological polishing method based on the adjustment of the polishing wheel rotation speed, which is realized by using the magnetorheological polishing system based on electromagnetic flowmeter sensing described in claim 4, characterized in that, It includes the following steps: S1: Set the theoretical initial values of the liquid pump speed and the corresponding magnetorheological fluid flow rate for each polishing point of the test polishing element, polish the test polishing element, change the vertical distance between the liquid pump and the nozzle, measure the magnetorheological fluid flow rate corresponding to different vertical distances through an electromagnetic flowmeter. If the magnetorheological fluid flow rate is different from the set theoretical initial value, adjust the liquid pump speed so that the magnetorheological fluid flow rate is the same as the set theoretical initial value, obtain the discrete data of the vertical distance and the liquid pump speed, and obtain the first conversion relationship between the vertical distance and the liquid pump speed through data fitting; among them, the first conversion relationship is expressed as , represents the liquid pump speed, represents the vertical distance, represents the conversion relationship between the vertical distance and the liquid pump speed; And at each vertical distance, different polishing gaps are set, and at each polishing gap, different polishing wheel rotation speeds are set. The flow rate of the magnetorheological fluid corresponding to different polishing wheel rotation speeds at each polishing gap is measured by an electromagnetic flowmeter, and discrete data of the polishing wheel rotation speed and the magnetorheological fluid flow rate at each polishing gap are obtained. Through data fitting, a fifth conversion relationship between the nozzle position and the corresponding magnetorheological fluid flow rate at each polishing gap is obtained. The fifth conversion relationship can be expressed as , where represents the polishing wheel rotation speed at each polishing gap, represents the flow rate of the magnetorheological fluid corresponding to the polishing wheel rotation speed at each polishing gap, represents the conversion relationship between the polishing wheel rotation speed and the magnetorheological fluid flow rate at each polishing gap; S2: According to the height change of the curved surface of the element to be polished, calculate the change in the rotational speed of the liquid pump based on the first conversion relationship, obtain the theoretical rotational speed of the liquid pump corresponding to each polishing point of the element to be polished, polish the element to be polished according to the theoretical rotational speed of each polishing point, and at the same time, monitor the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to each polishing point in real time through an electromagnetic flowmeter and send it to the computer; where the theoretical rotational speed of the liquid pump is expressed as , where represents the theoretical rotational speed of the liquid pump at each polishing point, i = 1, 2, 3... m, m represents the number of polishing points, represents the vertical distance of the i-th polishing point; S3: Set the allowable range of flow rate fluctuation in the computer. Determine whether the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point exceeds the set allowable range of flow rate fluctuation. If it does not exceed, keep the rotation speed of the polishing wheel at the polishing point unchanged. If it exceeds, control the drive motor to adjust the rotation speed of the polishing wheel at the polishing point until the actual magnetorheological fluid flow rate does not exceed the allowable range of flow rate fluctuation, so as to maintain the constant removal function of each polishing point.

18. The magnetorheological polishing method based on the polishing wheel rotation speed adjustment according to claim 17, wherein When polishing each polishing point of the element to be polished, set the dwell time for each polishing point, which specifically includes the following steps: S210: Establish the measurement coordinate system of the laser tracker so that the measurement coordinate system is parallel to the tool coordinate system of the industrial robot; S220: Drive the industrial robot to move towards the polishing platform so that the lowest point of the polishing wheel just touches the polishing platform. Place the target ball at the liquid outlet of the nozzle and measure the Z-axis coordinate Z4 of the target ball at this time; S230: Place the target ball on the polishing platform near the lowest point of the polishing wheel and measure the Z-axis coordinate of the target ball at this time. , then the vertical distance between the nozzle and the lowest point of the polishing wheel is , and the time required for the magnetorheological fluid ejected by the magnetorheological supply system to reach the lowest point of the polishing wheel is , where represents the number of revolutions per second of the polishing wheel, represents the length of the pipeline between the electromagnetic flowmeter and the nozzle, represents the flow rate of the magnetorheological fluid, represents the radius of the polishing wheel.

19. The magnetorheological polishing method based on the adjustment of the polishing wheel rotation speed according to claim 18, characterized in that, When a polishing control program is generated by a computer, if the dwell time of each polishing point is met, the generated polishing control program is appropriate; if there is a dwell time of a certain polishing point , then extend the dwell time of this polishing point , and regenerate the polishing control program so that the dwell time of each polishing point .

20. The magnetorheological polishing method based on the polishing wheel speed adjustment according to claim 17, characterized in that, In step S3, the maximum adjustment amount of the polishing wheel rotation speed is set in the computer to be ; And, If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is within the set allowable range of flow rate fluctuation keep the rotational speed of the polishing wheel at the current polishing point unchanged; If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current polishing wheel speed adjustment amount is [value], then adjust the current polishing wheel speed according to the following formula : ； If the actual flow rate of the magnetorheological fluid at the liquid outlet of the nozzle corresponding to the current polishing point is not within the set flow rate fluctuation tolerance range and the current polishing wheel speed adjustment amount is [value], then adjust the current polishing wheel speed according to the following formula : ； Among them, represents the initial rotational speed of the polishing wheel.

21. A magnetorheological polishing method based on removal function adjustment, which is realized by using the magnetorheological polishing system based on electromagnetic flowmeter sensing described in claim 1, characterized in that, It includes the following steps: S1: Set the theoretical initial value of the magnetorheological fluid flow rate for each polishing point of the test polishing element. Polish the test polishing element according to the theoretical initial value of the magnetorheological fluid flow rate to obtain the removal function. At the same time, measure the theoretical magnetorheological fluid flow rate corresponding to each polishing point of the test polishing element through an electromagnetic flowmeter, and calculate the sixth conversion relationship between the removal function and the theoretical magnetorheological fluid flow rate, where the sixth conversion relationship is expressed as , represents the removal function, represents the theoretical magnetorheological fluid flow rate for each polishing point of the test polishing element, represents the sixth conversion relationship between the theoretical magnetorheological fluid flow rate for each polishing point of the test polishing element and the removal function; S2: Set the allowable range of flow rate fluctuation in the computer. Conduct the first polishing on the element to be polished according to the theoretical magnetorheological fluid flow rate. Measure the actual magnetorheological fluid flow rate at the liquid outlet of the nozzle corresponding to each polishing point of the element to be polished through the electromagnetic flowmeter, and determine whether it exceeds the set allowable range of flow rate fluctuation. If it exceeds, record the actual magnetorheological fluid flow rate at the polishing point. After the first polishing of the element to be polished, calculate the removal function corresponding to the actual magnetorheological fluid flow rate recorded at each polishing point based on the sixth conversion relationship to obtain the variable removal function set; S3: Conduct the secondary polishing on the element to be polished according to the variable removal function set, and determine the polishing amount of each polishing point when polishing the element to be polished for the second time through the variable removal function set.

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