A deterministic polishing method and polishing device for shear thickening polishing

Abstract

The invention discloses a deterministic polishing method and a polishing device for shear thickening polishing. The method partially comprises: discretization of a surface to be processed, using measurement and interpolation methods to represent the surface to be processed in a computer with discretized control point coordinates; a polishing point controllable material removal matrix calculation strategy, planning polishing points, comparing the surface to be processed and the target surface, calculating the material removal allowance at the control point position, calculating the influence area of ​​each polishing point and the influence on the control point, and controllably merging the polishing points with the weighted value of the single point model of the adjacent polishing point removal allowance as the standard to obtain a material removal matrix; an iterative NNLS (non-negative least squares) joint residence time algorithm, first using an iterative method to calculate the residence time of the polishing point for the material removal matrix, reducing the fluctuation of the residence time solution result, and then using the NNLS (non-negative least squares) algorithm on this basis to further improve the accuracy of the result.

Description

Technical Field

[0001] The invention belongs to the technical field of automated processes, and in particular relates to a deterministic polishing method and a polishing device for shear thickening polishing. Background Art

[0002] In the prior art, fields such as energy utilization, beam shaping, laser manufacturing, and space imaging require compact, high-performance optical systems built on complex surfaces. Shear thickening polishing is an efficient, high-precision polishing method that uses the shear thickening effect of the polishing fluid to remove materials. The polishing fluid contains substances such as polyhydroxy polymers, abrasives, and dispersants. When the workpiece moves relative to the shear thickening fluid, a shear thickening effect will occur, causing the shear stress in the contact area to increase sharply, thereby efficiently removing the workpiece surface material. However, non-deterministic material removal within the processing range will cause the surface shape of the processed surface to fail to meet the accuracy requirements. In the polishing process of the surface, the application of deterministic polishing technology can achieve deterministic material removal to obtain a high-precision polished surface shape. Deterministic polishing refers to removing a specified amount of material at each point on the workpiece surface by precisely controlling the polishing parameters to achieve the purpose of surface shape control.

[0003] Traditional deterministic polishing requires an integral calculation of the material removal of the polishing point based on the polishing path to obtain the material removal effect on the surface when the polishing area completely passes through the polishing point at a unit speed. This material removal calculation method requires a large number of integral calculations, but when the polishing points are densely set, that is, when there are more than one polishing point in a polishing area, the feed time obtained under this calculation method will conflict. At the same time, the integral calculation also consumes a lot of computing resources. Using discretized fixed-point material removal calculations can avoid conflicts in feed time results. However, compared with integral calculations, discretized fixed-point material removal calculations require setting a large number of polishing points to enhance calculation accuracy, which also consumes a lot of computing resources.

[0004] The invention patent "Optical Parts Processing Method and System" (publication number CN 115194601 A) provides an optical parts processing method and system to achieve the convergence of high, medium and low frequency surface errors, but does not specifically disclose how to perform targeted polishing based on the surface error information obtained by detection. The invention patent "Regional Adaptive Smoothing Polishing Path Planning Method" (publication number CN 115952568 A) discloses a regional adaptable smoothing polishing path planning method and system, which divides sub-regions according to the peak and valley positions of the removed surface, plans double helix paths in the sub-regions and connects them to each other, and finally calculates the residence time and outputs the corresponding feed speed. However, this method does not provide a calculation method for the residence time density matrix, does not optimize the calculation amount for the calculation method, and mainly focuses on deterministic polishing trajectory planning. The invention patent "A method for solving the dwell time of deterministic optical polishing technology" (publication number CN 110842652 A) discloses a method for solving the dwell time of deterministic optical polishing technology, which uses the speed and acceleration performance of the machine tool to constrain the calculation of the dwell time, calls the bilateral constrained least squares solver to solve the model to obtain the dwell time and the feed speed, but does not disclose the calculation method of the material removal rate, and does not optimize the number of polishing points. The invention patent "A rocker-type polishing device and method for full-aperture deterministic polishing of planar parts" (publication number CN 111266937 A) discloses a rocker-type polishing device and method for full-aperture deterministic polishing of planar parts, which takes into account the surface shape of the workpiece. However, this deterministic polishing method requires trimming the surface shape of the polishing pad, rather than performing deterministic polishing by changing parameters during polishing. It can only achieve deterministic polishing of planar parts, and the processing has limitations. Summary of the invention

[0005] In order to make up for the shortcomings of the prior art, the present invention provides a deterministic polishing method and a polishing device for shear thickening polishing to solve the technical problems that the existing shear thickening polishing method is difficult to control the polishing surface shape, the deterministic polishing method has a large amount of calculation, and the obtained feed time has conflicts in some cases.

[0006] To achieve the above purpose, the specific technical solutions of the present invention are as follows:

[0007] In a first aspect, a deterministic polishing method for shear thickening polishing comprises:

[0008] S1: Use the instrument to measure the surface to be processed, and obtain the discretized three-dimensional data of the surface to be processed, which is represented by control points;

[0009] S2: planning a polishing path, planning a plurality of initial polishing points on the polishing path, and calculating the material removal amount of each polishing point relative to the corresponding control point position;

[0010] S3: Using the controllable material removal matrix of the polishing point, calculating the strategy planning combined polishing points, and obtaining the material removal matrix;

[0011] S4: Use an iterative algorithm to obtain the initial dwell time of the polishing point, calculate the remaining material removal allowance of the control point with the dwell time obtained by the iterative algorithm, and use the NNLS (non-negative least squares) algorithm to calculate the final dwell time of the polishing point.

[0012] Furthermore, in step S1, the data obtained by measuring the surface to be processed by an instrument is expanded into data arranged in sequence and at equal intervals on the x0y plane by a linear interpolation method, namely, control points.

[0013] Furthermore, the specific steps of obtaining the material removal amount in step S2 are as follows:

[0014] S2.1: Plan a grid polishing path on the surface of the workpiece to be processed, and set the polishing points on the polishing path at equal intervals.

[0015] S2.2: Use coordinate transformation and translation methods to map the coordinate data of the surface of the workpiece to be processed to the target surface. The target surface is represented by a fitting formula or discrete points. The vertical normal vector of the corresponding control point on the target surface is calculated. The modulus of the vector to the surface to be processed is calculated to obtain the material removal allowance of each control point.

[0016] Furthermore, the steps of obtaining the material removal matrix in step S3 are as follows:

[0017] S3.1: Calculate the positions of all control points relative to all polishing points;

[0018] S3.2: Substitute the control point relative to a certain polishing point into Formula 1 to obtain the material removal influence factor MRR (x, y) of the polishing point on all control points, traverse all polishing points, and obtain the material removal influence factor MRR (x, y) of each polishing point on all control points;

[0019] (1)

[0020] in, and is the fluid flow rate and pressure in the polishing area, is the abrasive particle diameter, is the abrasive particle radius, is the Brinell hardness value of the workpiece surface, is the abrasive volume concentration, It is the actual effective abrasive coefficient of the polishing affected area.

[0021] S3.3: The influence range of each polishing point is obtained according to the presence or absence of the material removal influencing factor, and the weighted removal allowance of all control points in the influence area of ​​each polishing point is calculated using Formula 2 to indicate the material removal requirement of each polishing point. Each polishing point corresponds to a weighted removal allowance;

[0022] (2)

[0023] in, For polishing point Affects every control point in the area The sum of the required weighted material removal; m is the number of control points; i is the i-th control point; The material removal allowance for the i-th control point; represents the material removal influence vector of the jth polishing point; Indicates the polishing points per unit time Control Point the depth of material removal caused;

[0024] S3.4: Calculate the difference of weighted removal margins corresponding to adjacent polishing points, and sort the difference values ​​from small to large to obtain a weighted removal margin sequence;

[0025] S3.5: The path sequence is used as the direction of grouping, the weighted removal residue sequence value is used as the grouping standard, and the arrangement order of the weighted removal residue sequence is used as the selection order of the grouping standard. The groups are grouped in sequence. The grouping condition is that the difference between the maximum and minimum values ​​of the weighted removal residue of the polishing points in the group is not greater than the weighted removal residue sequence value or the polishing points in the group are not greater than the set maximum number of polishing points in the group. After the preliminary grouping is completed, if the number of groups is greater than the set number of groups, the next larger weighted removal residue sequence value is selected for grouping until the grouping requirements are met to obtain the final grouping;

[0026] S3.6: Based on the final grouping result, the influence removal factors of the polishing points in each group on the control points are superimposed to obtain a combined material removal influence matrix;

[0027] Furthermore, the steps of obtaining the preliminary polishing point residence time in step S4 are as follows:

[0028] S4.1: Set a uniform minimum iterative dwell time for all polishing point groups;

[0029] S4.2: multiplying the material removal matrix by the cumulative dwell time vector, and accumulating the cumulative dwell time of each polishing point group and the cumulative material removal amount of the control point;

[0030] S4.3: traverse the control points in the polishing point influence area in all iterations, determine the cumulative material removal amount of each control point, and set the minimum iteration residence time corresponding to the polishing point group of control points in all influence areas with cumulative material removal amounts greater than or equal to the material removal margin to 0. If the minimum iteration residence time corresponding to all polishing point groups is 0, jump to step S4.5;

[0031] S4.4: Use formula 3 to calculate the difference between the cumulative material removal amount of the control points in the area affected by the remaining polishing point group and the material removal allowance, divide the difference by the material removal amount of each control point after one iteration, and the smallest quotient rounded up is the acceleration step length. The non-zero value of the residence time vector corresponding to the minimum iteration residence time plus the acceleration step length multiplied by the minimum iteration residence time is taken as the cumulative residence time vector, and jump to step S4.2;

[0032] (3)

[0033] in, It is the value of the acceleration step multiplied by the minimum iteration residence time, that is, the acceleration iteration residence time vector; Material removal vector for all control points where iterations have not stopped; is the material removal vector after the last iteration; It is the material removal amount vector of all control points that have not stopped iteration when iterating once with the minimum iteration residence time based on the cumulative iteration residence time; is the minimum iteration residence time vector; is the acceleration step length.

[0034] S4.5: Calculate the remaining material removal of all control points, use the NNLS (non-negative least squares) algorithm to calculate the dwell time vector required for polishing remaining material removal, and obtain the NNLS (non-negative least squares) dwell time vector;

[0035] S4.6: The cumulative dwell time vector is added to the NNLS (non-negative least squares) dwell time vector to obtain the final dwell time of each polishing point group.

[0036] In a second aspect, a deterministic polishing device for shear thickening polishing includes a stirring tank, a polishing tank, a powder metering module, a stirring module, a conveying module and a polishing processing module.

[0037] A water injection pipe is provided on the water inlet of the stirring tank, which is used to inject a certain amount of water into the stirring tank.

[0038] The powder injection module is arranged just above the stirring tank, and is used to add a set weight of polishing liquid raw materials into the stirring tank, and stir the polishing liquid through the stirring module to form the polishing liquid.

[0039] The conveying module is used to convey the formed polishing liquid to the polishing pool and the stirring pool in sequence, thereby forming a flow circulation of the polishing liquid.

[0040] The polishing processing module is used for polishing the workpiece to be processed in the polishing pool.

[0041] Furthermore, the powder metering module includes a feeding component and a weighing component. The weighing component is installed directly above the feeding component, and can weigh the powder output by the feeding component and pour it when it reaches a specified weight.

[0042] The feeding assembly includes a stepper motor, a screw and a feeding base. The feeding base is provided with a feeding trough and a powder material transmission trough which are connected in sequence. The screw is rotatably connected in the powder material transmission trough and can be rotated under the drive of the stepper motor, thereby realizing the stepwise output of the powder falling into the powder material transmission trough to the weighing assembly.

[0043] Furthermore, the weighing assembly includes a supporting platform, and a feeding platform, an electronic scale and an electric cylinder mounted on the supporting platform. The end of the feeding platform is rotatably connected to the supporting platform and can be switched between a horizontal state and an inclined state under the drive of the electric cylinder. The electronic scale is fixed on the feeding platform.

[0044] Furthermore, the stirring module includes a stirring paddle and a driving motor. The stirring paddle is rotatably connected in the stirring tank and can be rotated by the driving motor to stir the injected water and the polishing powder and polyhydroxy polymer powder falling into the stirring tank to form a polishing liquid.

[0045] Furthermore, the delivery module includes two rotor pumps and two three-way valves. The two rotor pumps are divided into a first rotor pump connected to the output end of the stirring tank, and a second rotor pump connected to the output end of the polishing tank. The two three-way valves are divided into a first three-way valve arranged on the pipeline between the first rotor pump and the polishing tank; and a second three-way valve arranged on the output end of the second rotor pump. An online particle size analyzer is arranged between the first rotor pump and the first three-way valve, which is used to monitor the mixing and component conditions of the polishing liquid output from the stirring tank in real time.

[0046] The first three-way valve and the second three-way valve are respectively provided with a first reflux pipe and a second reflux pipe for being connected to the stirring tank.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] 1. The present invention plans polishing points through a controllable material removal matrix calculation strategy of polishing points, compares the surface to be processed and the target surface, calculates the material removal allowance at the control point position, calculates the influence area of ​​each polishing point and the influence on the control point, and controllably merges the polishing points based on the weighted value of the single-point model of the adjacent polishing point removal allowance to obtain a material removal matrix; the amount of calculation required for deterministic polishing planning is greatly and controllably reduced, and the feed time (equivalent to the dwell time) result obtained while greatly increasing the density of polishing points will not have a value of 0, thereby avoiding conflicts between the dwell time results of the polishing points obtained by the algorithm itself.

[0049] 2. The present invention sets an online particle size analyzer at the input end of the polishing liquid, cooperates with the feeding component and the weighing component, and automatically stabilizes the polishing liquid components before and during polishing to stabilize the viscosity of the polishing liquid. On this basis, the stability control of the polishing material during the shear thickening polishing process can be stably achieved to obtain a high-precision polishing surface shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the overall structure of a deterministic shear thickening polishing device in an embodiment of the present invention;

[0051] Figure 2 is a schematic diagram of the structure of a powder injection module in an embodiment of the present invention;

[0052] Figure 3 is a schematic flow chart of the steps of a deterministic polishing method in an embodiment of the present invention;

[0053] Figure 4 It is a flow chart of the steps of calculating the controllable material removal matrix of the polishing point in the deterministic polishing method according to the embodiment of the present invention;

[0054] Figure 5 is a flow chart of the steps of the iterative-NNLS combined dwell time algorithm in the deterministic polishing method in an embodiment of the present invention;

[0055] Figure 6 Schematic diagram of the effect of the controllable material removal matrix calculation strategy of the polishing point in the deterministic polishing method in the embodiment of the present invention;

[0056] Figure 7 Schematic diagram of the effect of the iterative-NNLS combined dwell time algorithm in the deterministic polishing method in an embodiment of the present invention;

[0057] Figure 8 It is a display diagram of the surface morphology obtained before and after polishing in the deterministic polishing method experiment in the embodiment of the present invention;

[0058] Fig. 9This is a graph showing the surface roughness obtained after polishing in the deterministic polishing method experiment in the embodiment of the present invention.

[0059] Figure numerals: 1. stirring tank; 2. polishing tank; 3. powder metering module; 3-1. feeding assembly; 3-1-1. stepping motor; 3-1-2. screw; 3-1-3. feeding base; 3-2. weighing assembly; 3-2-1. supporting platform; 3-2-2. feeding platform; 3-2-3. electronic scale; 3-2-4. electric cylinder; 4. stirring module; 5. polishing processing module; 6. electric control valve; 7. flow meter; 8. first rotor pump; 9. second rotor pump; 10. first three-way valve; 10-1. first input end; 10-2. first reflux end; 10-3. conveying end; 11. second three-way valve; 11-1. second input end; 11-2. second reflux end; 11-3. output end; 12. online particle size analyzer. DETAILED DESCRIPTION

[0060] In the description of the present invention, it is necessary to understand that the terms "one end", "the other end", "outside", "upper", "inside", "horizontal", "coaxial", "center", "end", "length", "outer end" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0061] The present invention will be further described below in conjunction with the accompanying drawings.

[0062] like Figure 1 and 2 As shown, a deterministic polishing device for shear thickening polishing includes a stirring tank 1, a polishing tank 2, a powder metering module 3, a stirring module 4, a conveying module and a polishing processing module 5. Among them, a water injection pipe is provided on the water inlet of the stirring tank 1. The water injection pipe is sequentially provided with an electric control valve 6 and a flow meter 7, which can inject a certain amount of water into the stirring tank 1. The powder metering module 3 is used to add a set weight of polishing liquid raw materials into the stirring tank 1, and stir it through the stirring module 4 to form a polishing liquid. The conveying module is used to convey the formed polishing liquid to the polishing tank 2 and the stirring tank 1 in turn, thereby forming a flow circulation of the polishing liquid. The polishing processing module 5 is used to polish the workpiece to be processed in the polishing tank 2.

[0063] In the present embodiment, the polishing liquid raw materials include polishing powder and polyhydroxy polymer powder. There are two powder metering modules 3, which are used to input polishing powder and polyhydroxy polymer powder into the stirring pool 1 respectively. The powder metering module 3 includes a feeding component 3-1 and a weighing component 3-2. Among them, the weighing component 3-2 is arranged directly below the output end 11-3 of the feeding component 3-1. The feeding component 3-1 is used to gradually input polishing powder or polyhydroxy polymer powder into the weighing component 3-2, and weigh it through the weighing component 3-2. When the weighing component 3-2 receives the powder of the specified weight, it will shake off the weighed powder into the stirring pool 1.

[0064] Specific structure such as Figure 2 As shown, the feed assembly 3-1 includes a stepper motor 3-1-1, a screw 3-1-2 and a feed base 3-1-3. The feed base 3-1-3 is provided with a feed trough and a powder transmission trough which are connected in sequence. The screw 3-1-2 is rotatably connected in the powder transmission trough and can be rotated under the drive of the stepper motor 3-1-1. When in use, the staff adds polishing powder or polyhydroxy polymer powder to the feed trough. The driving screw 3-1-2 of the stepper motor 3-1-1 rotates, and the powder falling into the powder transmission trough is gradually output to the weighing assembly 3-2.

[0065] The weighing assembly 3-2 includes a supporting platform 3-2-1, a feeding platform 3-2-2, a high-precision electronic scale 3-2-3 and an electric cylinder 3-2-4 installed on the supporting platform 3-2-1. The end of the feeding platform 3-2-2 is rotatably connected to the supporting platform 3-2-1, and can be switched between a horizontal state and an inclined state under the drive of the electric cylinder 3-2-4. The high-precision electronic scale 3-2-3 is fixed on the feeding platform 3-2-2.

[0066] When the feeding platform 3-2-2 is in a horizontal state, the high-precision electronic scale 3-2-3 receives the polishing powder output from the screw 3-1-2 and weighs it. When the feeding platform 3-2-2 changes from a horizontal state to an inclined state, the high-precision electronic scale 3-2-3 will be tilted. The powder on the weighing plane of the high-precision electronic scale 3-2-3 slides into the stirring tank 1.

[0067] In this embodiment, a piezoelectric vibrating plate is provided under the weighing plane of the high-precision electronic scale 3-2-3, which can vibrate at a high frequency under the inverse piezoelectric effect to fully shake off the powder on the weighing plane of the high-precision electronic scale 3-2-3.

[0068] The stirring module 4 includes a stirring paddle and a driving motor. The stirring paddle is rotatably connected to the stirring tank 1 and can rotate under the drive of the driving motor to stir the injected water, the stirring polishing powder and the polyhydroxy polymer powder to form a polishing liquid.

[0069] like Figure 1As shown, the delivery module includes two rotor pumps and two three-way valves. The two rotor pumps are divided into a first rotor pump 8 connected to the output end 11-3 of the stirring tank 1, and a second rotor pump 9 connected to the output end 11-3 of the polishing tank 2. The two three-way valves are divided into a first three-way valve 10 connected to the output end 11-3 of the first rotor pump 8, and a second three-way valve 11 connected to the output end 11-3 of the second rotor pump 9. Among them, an online particle size analyzer 12 is provided between the first rotor pump 8 and the first three-way valve 10, which is used to monitor the mixing and component conditions of the polishing liquid output from the stirring tank 1 in real time to ensure that the polishing liquid meets the required requirements.

[0070] In this embodiment, the three ports of the first three-way valve 10 are divided into a first input end 10-1, a first reflux end 10-2 and a delivery end 10-3. The first input end 10-1 is connected to the linear particle size analyzer through a corresponding water delivery pipe. The first reflux end 10-2 is provided with a first reflux pipe for returning the polishing liquid to the stirring pool 1. The delivery end 10-3 is provided with a water outlet pipe for outputting the polishing liquid to the polishing pool 2.

[0071] During use, when the online particle size analyzer 12 detects that the components of the polishing liquid do not meet the use requirements, the delivery end 10-3 on the first three-way valve 10 is cut off and the first reflux end 10-2 is turned on. The polishing liquid flows back to the stirring tank 1 through the first reflux pipe to continue stirring. When the components of the polishing liquid meet the use requirements after detection by the online particle size analyzer 12, the first reflux end 10-2 on the first three-way valve 10 is cut off and the delivery end 10-3 is turned on. The polishing liquid is transported to the polishing tank 2 through the outlet pipe for polishing.

[0072] In this embodiment, a polishing liquid nozzle is provided at the outer end of the water outlet pipe, which can evenly spray the polishing liquid onto the polishing area of ​​the workpiece being processed in the polishing pool 2.

[0073] The three ports of the second three-way valve 11 are divided into a second input end 11-1, a second return end 11-2 and an output end 11-3. Among them, the second input end 11-1 is connected to the output end 11-3 of the second rotor pump 9 through a corresponding water pipe. A second return pipe is provided on the second return end 11-2. The outer end of the second return pipe is connected to the first return pipe, which is used to return the polishing liquid to the stirring tank 1. A drain pipe is provided on the output end 11-3, which is used to discharge the polishing liquid that has completed the operation to the outside.

[0074] In the initial state, the second return end 11-2 in the second three-way valve 11 is cut off, and the second input end 11-1 and the output end 11-3 are connected, so as to prevent the polishing liquid whose components do not meet the requirements from being transported to the polishing pool 2 through the second return pipe. When the components of the polishing liquid meet the requirements, the output end 11-3 is cut off, the second input end 11-1 and the second return end 11-2 are connected, and the polishing liquid that does not pass through the workpiece can be transported to the stirring pool 1 through the second rotor pump 9 and the second return pipe, and cooperate with the first rotor pump 8 to form a circulation operation.

[0075] The polishing processing module 5 uses an ABB1410 robot arm with a main shaft, and a spherical polishing head with a diameter of 12 cm is provided at the end of the main shaft. When in use, the spherical polishing head with a diameter of 12 cm at the end is driven by the main shaft to feed and polish at a speed of 5000 rpm and a distance of 200um from the workpiece.

[0076] The polishing operation process of the polishing device includes:

[0077] The workpiece selected for processing is a 30 mm×30 mm flat BK7 glass, the processing area is the middle 20 mm×20 mm range, and it is installed in the polishing pool 2.

[0078] Set the amount of polishing powder, polyhydroxy polymer powder, and water. The stepper motor 3-1-1 in the two powder injection modules 3 drives the screw 3-1-2 to rotate, pushing the polishing powder and polyhydroxy polymer powder in the powder transfer trough forward and falling onto the high-precision electronic scale 3-2-3. After the high-precision electronic scale 3-2-3 has weighed enough powder, the electric cylinder 3-2-4 fixed to the support platform 3-2-1 extends, and under the action of the roller, the tilting platform drives the high-precision electronic scale 3-2-3 to tilt. At the same time, the piezoelectric vibrating piece fixed under the weighing plane of the high-precision electronic scale 3-2-3 begins to vibrate at high frequency under the reverse piezoelectric action to fully shake off the powder on the weighing plane of the high-precision electronic scale 3-2-3.

[0079] The delivery end 10-3 in the first three-way valve 10 connected to the online particle size analyzer 12 is cut off, and the first reflux end 10-2 and the first input end 10-1 are connected, so that the polishing liquid output by the first rotor pump 8 can be returned to the stirring tank 1 after being detected by the online particle size analyzer 12. The second reflux end 11-2 in the second three-way valve 11 is cut off, and the second input end 11-1 and the output end 11-3 are connected to prevent the polishing liquid in the pipeline from flowing out.

[0080] A fixed amount of water is injected into the stirring tank 1, and the stirring paddle is driven by the driving motor to rotate. The injected water, the polishing powder and the polyhydroxy polymer powder falling into the stirring tank are stirred by the stirring paddle to form a polishing liquid. The formed polishing liquid is output through the first rotor pump 8 and flows through the online particle size analyzer 12. The online particle size analyzer 12 monitors the mixing and component conditions of the circulating polishing liquid in real time. If the polishing liquid does not meet the required requirements, it will flow back to the stirring tank 1 through the first reflux pipe.

[0081] When the polishing liquid is fully mixed and the components meet the requirements, the first rotor pump 8 is turned off, and the first reflux end 10-2 on the first three-way valve 10 is cut off, and the delivery end 10-3 is connected; the output end 11-3 on the second three-way valve 11 is cut off, and the second input end 11-1 and the second reflux end 11-2 are connected. The polishing liquid output from the stirring pool 1 is input into the polishing pool 2 under the drive of the first rotor pump 8, and flows back to the stirring pool 1 through the second rotor pump 9.

[0082] Initially, the flow rate of the second rotor pump 9 is less than the flow rate of the first rotor pump 8, so that the polishing liquid input into the polishing pool 2 is more than the polishing liquid returned to the stirring pool 1. When the polishing liquid in the polishing pool 2 submerges the processing area, the flow rate of the second rotor pump 9 and the flow rate of the first rotor pump 8 are adjusted to a consistent state, so that the polishing liquid can form a flow circulation between the polishing pool 2 and the stirring pool 1.

[0083] Subsequently, the ABB1410 robot arm equipped with a spindle drives the spherical polishing head with a diameter of 12 cm at the end to perform feed polishing at a speed of 5000 rpm and a distance of 200 um from the workpiece. During the polishing process, if the online particle size analyzer 12 detects that the composition of the polishing liquid has changed, the two powder injection modules 3 and the water injection pipe add powder and water to the stirring tank 1 to adjust the composition of the polishing liquid.

[0084] After polishing is completed, the first rotor pump 8 and the second rotor pump 9 are closed, and the second three-way valve 11 is adjusted to a state where the second reflux end 11-2 is cut off and the second input end 11-1 and the output end 11-3 are connected. At the same time, the first rotor pump 8 and the second rotor pump 9 are started, and the polishing liquid output from the polishing pool 2 flows through the second rotor pump 9 and the second three-way valve 11, and is discharged from the output end 11-3 of the second three-way valve 11.

[0085] After the polishing liquid is discharged, the electric control valve 6 is opened to allow clean water to flow into the stirring tank 1 through the water injection pipe. The stirring tank 1, the polishing tank 2, and each pipe are cleaned by the cooperation of the first rotor pump 8, the second rotor pump 9, and the first three-way valve 10 and the second three-way valve 11.

[0086] like Figure 3 As shown, the feed route and feed speed during the polishing process are provided by the proposed deterministic polishing method for shear thickening polishing, which specifically includes the following steps:

[0087] S1: Use ZYGO GPI XP / D laser interferometer to measure the surface to be processed, obtain the discretized three-dimensional data of the surface to be processed, and use the linear interpolation method to expand the three-dimensional data into data with a spacing of 0.25 mm between adjacent data points on the x0y plane. The expanded data is the control point.

[0088] S2: Plan the polishing path, plan the initial polishing point on the polishing path, and calculate the material removal amount between the control point and the polishing point, including:

[0089] S2.1: Plan a grid polishing path on the surface to be processed, with a grid spacing of 1 mm. Polishing points are set at equal intervals on the polishing path, and the spacing between adjacent polishing points on the polishing path is 0.2 mm. The setting of the polishing path has ensured that the polishing area traverses the surface to be processed to form a target surface.

[0090] S2.2: Use coordinate transformation and translation methods to map the coordinate data of the surface to be processed to the target surface, ensure that the surface to be processed is higher than the target surface and the two surfaces do not overlap, calculate the vertical normal vector of the corresponding control point on the target surface, calculate the modulus of the vector to the surface to be processed, and use this as the material removal allowance corresponding to the control point.

[0091] S3: Figure 4 As shown, the polishing point controllable material removal matrix calculation strategy is used to plan the combined polishing points to obtain the material removal matrix, which specifically includes:

[0092] S3.1: Calculate the positions of all control points relative to all polishing points.

[0093] S3.2: Substitute all control points relative to a certain polishing point into formula 1 to obtain the material removal influence factor MRR (x, y) of the polishing point on all control points. Traverse all polishing points to obtain the material removal influence factor MRR (x, y) of each polishing point on all control points.

[0094] (1)

[0095] in, and is the fluid flow rate and pressure in the polishing area, is the abrasive particle diameter, is the abrasive particle radius, is the Brinell hardness value of the workpiece surface, is the abrasive volume concentration, It is the actual effective abrasive coefficient of the polishing affected area.

[0096] S3.3: The influence range of each polishing point is obtained based on the presence or absence of the material removal influencing factor, and the weighted removal allowance of all control points in the influence area of ​​each polishing point is calculated using Formula 2 to indicate the material removal requirement of each polishing point. Each polishing point corresponds to a weighted removal allowance.

[0097] (2)

[0098] in, For polishing point Affects every control point in the area The sum of the required weighted material removal; m is the number of control points; i is the i-th control point; The material removal allowance for the i-th control point; represents the material removal influence vector of the jth polishing point; Indicates the polishing points per unit time Control Point The resulting material removal depth.

[0099] S3.4: Calculate the difference in weighted removal allowances corresponding to adjacent polishing points in the feed direction, and sort the differences from small to large to obtain a weighted removal allowance sequence.

[0100] S3.5: Use the path order as the direction of grouping, the weighted removal residue sequence value as the grouping standard, and the arrangement order of the weighted removal residue sequence as the selection order of the grouping standard, and group them in sequence. The grouping condition is that the difference between the maximum and minimum values ​​of the weighted removal residue of the polishing points in the group is not greater than the weighted removal residue sequence value or the polishing points in the group are not greater than the set maximum number of polishing points in the group. After the initial grouping is completed, if the number of groups is greater than the set number of groups, select the next larger weighted removal residue sequence value for grouping until the grouping requirements are met to obtain the final grouping.

[0101] S3.6: Based on the final grouping results, the influence removal factors of the polishing points in each group on the control points are superimposed to obtain a combined material removal influence matrix.

[0102] S4: Figure 5 As shown, an iterative algorithm is used to obtain the preliminary dwell time of the polishing point, the dwell time obtained by the iterative algorithm is used to calculate the remaining material removal allowance of the control point, and the NNLS (non-negative least squares) algorithm is used to calculate the final dwell time of the polishing point.

[0103] S4.1: Set a uniform minimum iterative dwell time value for all polishing point groups;

[0104] S4.2: multiply the material removal matrix by the cumulative dwell time vector (at the beginning, each value of the cumulative dwell time vector is the minimum iterative dwell time value), and add up the cumulative dwell time of each polishing point group and the cumulative material removal amount of the control point;

[0105] S4.3: traverse the control points in the polishing point influence area in all iterations, determine the cumulative material removal amount of each control point, and set the minimum iteration residence time corresponding to the polishing point group of control points in all influence areas with cumulative material removal amounts greater than or equal to the material removal margin to 0. If the minimum iteration residence time corresponding to all polishing point groups is 0, jump to step S4.5;

[0106] S4.4: Use formula 3 to calculate the difference between the cumulative material removal amount of the control points in the area affected by the remaining polishing point group and the material removal allowance, divide the difference by the material removal amount of each control point after one iteration, and the smallest quotient rounded up is the acceleration step length. The non-zero value of the residence time vector corresponding to the minimum iteration residence time plus the acceleration step length multiplied by the minimum iteration residence time is taken as the cumulative residence time vector, and jump to step S4.2;

[0107] (3)

[0108] in, It is the value of the acceleration step multiplied by the minimum iteration residence time, that is, the acceleration iteration residence time vector; Material removal vector for all control points where iterations have not stopped; is the material removal vector after the last iteration; It is the material removal amount vector of all control points that have not stopped iteration when iterating once with the minimum iteration residence time based on the cumulative iteration residence time; is the minimum iteration residence time vector; is the acceleration step length.

[0109] S4.5: Calculate the remaining material removal of all control points, use the NNLS algorithm to calculate the dwell time vector required for the polishing remaining material removal, and obtain the NNLS dwell time vector;

[0110] S4.6: The accumulated dwell time vector is added to the NNLS dwell time vector to obtain the final dwell time of each polishing point group.

[0111] S4.7: Split the polishing point groups, the dwell time of all polishing points in a group is the dwell time of the group, and the dwell time of all polishing points is obtained.

[0112] Select a 30mm×30mm plane with a BK7 glass processing area of ​​20mm×20mm in the middle as the workpiece to be processed and perform the above steps.

[0113] like Figure 6 As shown, the effect of the polishing point controllable material removal matrix calculation strategy on the machined workpiece is shown, where Figure 6 (a), (b), and (c) show the distribution of polishing point groups when the number of polishing points is set to 2000, 1500, and 1000, respectively. The z coordinate is the weighted material removal of the polishing point. Polishing points will be combined preferentially at locations where the weighted material removal changes slowly.

[0114] like Figure 7 As shown in the figure, the residence time results obtained by applying the iterative-NNLS joint residence time algorithm are compared. Figure 7 (a) is the residence time result obtained by the iterative-NNLS joint residence time algorithm. The residence time obtained has a gentle and regular change amplitude and no zero value. Figure 7 (b) in the figure is the residence time result obtained by using the NNLS algorithm alone. There are a large number of zero values ​​in the result (marked with a "+" sign). At the same time, the residence time results of non-zero values ​​vary greatly and the change range is not smooth.

[0115] like Figure 8 As shown in the figure, the surface morphology of the workpiece before and after polishing is measured by ZYGO GPI XP / D laser interferometer, where: Figure 8 (a) and (c) are before polishing. Figure 8 (b) and (d) are after polishing. Figure 8 The data marked in (c) and (d) are the relative heights of the highest and lowest points of the surface. The PV value of the surface before polishing is 104.28nm, and the PV value of the surface after polishing is 35.03nm, which is closer to the plane.

[0116] like Fig. 9 As shown in the figure, the surface roughness of the polished workpiece is measured by using Veeco Wyko NT9100, and the roughness Ra of the polished surface is about 1nm.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A deterministic polishing method for shear thickening polishing, characterized in that: The following steps are involved: S1: Use the instrument to measure the surface to be processed, and obtain the discretized three-dimensional data of the surface to be processed, which is represented by control points; S2: planning a polishing path, planning a plurality of initial polishing points on the polishing path, and calculating the material removal amount of each polishing point relative to the corresponding control point position; S3: Using the controllable material removal matrix of the polishing point, calculating the strategy planning combined polishing points, and obtaining the material removal matrix; S3.1: Calculate the positions of all control points relative to all polishing points; S3.2: Substitute the control point relative to a certain polishing point into Formula 1 to obtain the material removal influence factor MRR(x,y) of the polishing point on all control points. Traverse all polishing points to obtain the material removal influence factor MRR(x,y) of each polishing point on all control points. Among them, v s (x, y) and P(x, y) are the fluid velocity and pressure in the polishing area, D is the abrasive diameter, r is the abrasive radius, H b is the Brinell hardness value of the workpiece surface, μ d is the abrasive volume concentration, k l It is the actual effective abrasive coefficient of the polishing affected area; S3.3: The influence range of each polishing point is obtained according to the presence or absence of the material removal influencing factor. Formula 2 is used to calculate the weighted removal allowance of all control points in the influence area of ​​each polishing point to indicate the material removal requirement of each polishing point. Each polishing point corresponds to a weighted removal allowance; in, Polishing point P j Each control point M in the affected area i The sum of the required weighted material removal; m is the number of control points; i is the i-th control point; α i is the material removal allowance of the i-th control point; E j represents the material removal influence vector of the jth polishing point; e ij Indicates the polishing point P per unit time j For control point M i the depth of material removal caused; S3.4: Calculate the difference of weighted removal margins corresponding to adjacent polishing points, and sort the difference values ​​from small to large to obtain a weighted removal margin sequence; S3.5: The path sequence is used as the direction of grouping, the weighted removal residue sequence value is used as the grouping standard, and the arrangement order of the weighted removal residue sequence is used as the selection order of the grouping standard. The groups are grouped in sequence. The grouping condition is that the difference between the maximum and minimum values ​​of the weighted removal residue of the polishing points in the group is not greater than the weighted removal residue sequence value or the polishing points in the group are not greater than the set maximum number of polishing points in the group. After the preliminary grouping is completed, if the number of groups is greater than the set number of groups, the next larger weighted removal residue sequence value is selected for grouping until the grouping requirements are met to obtain the final grouping; S3.6: Based on the final grouping result, the influence removal factors of the polishing points in each group on the control points are superimposed to obtain a combined material removal influence matrix; S4: using an iterative algorithm to obtain a preliminary dwell time of the polishing point, using the dwell time obtained by the iterative algorithm to calculate the remaining material removal margin of the control point, and using non-negative least squares to calculate the final dwell time of the polishing point.

2. A deterministic polishing method for shear thickening polishing according to claim 1, characterized in that: In the step S1, the data obtained by measuring the surface to be processed by an instrument is expanded into data arranged in sequence and at equal intervals on the x0y plane by a linear interpolation method, namely, control points.

3. A deterministic polishing method for shear thickening polishing according to claim 1, characterized in that: The specific steps of obtaining the material removal amount in step S2 are as follows: S2.1: Plan a grid polishing path on the surface of the workpiece to be processed, and set the polishing points on the polishing path at equal intervals; S2.2: Use coordinate transformation and translation methods to map the coordinate data of the surface of the workpiece to be processed to the target surface. The target surface is represented by a fitting formula or discrete points. The vertical normal vector of the corresponding control point on the target surface is calculated. The modulus of the vector to the surface to be processed is calculated to obtain the material removal allowance of each control point.

4. A deterministic polishing method for shear thickening polishing according to claim 1, characterized in that: The steps for obtaining the preliminary polishing point residence time in step S4 are as follows: S4.1: Set a uniform minimum iterative dwell time for all polishing point groups; S4.2: multiplying the material removal matrix by the cumulative dwell time vector, and accumulating the cumulative dwell time of each polishing point group and the cumulative material removal amount of the control point; S4.3: traverse the control points in the polishing point influence area in all iterations, determine the cumulative material removal amount of each control point, and set the minimum iteration residence time corresponding to the polishing point group of control points in all influence areas with cumulative material removal amounts greater than or equal to the material removal margin to 0. If the minimum iteration residence time corresponding to all polishing point groups is 0, jump to step S4.5; S4.4: Use formula 3 to calculate the difference between the cumulative material removal amount of the control points in the area affected by the remaining polishing point group and the material removal allowance, divide the difference by the material removal amount of each control point after one iteration, and the smallest quotient rounded up is the acceleration step length. The non-zero value of the residence time vector corresponding to the minimum iteration residence time plus the acceleration step length multiplied by the minimum iteration residence time is taken as the cumulative residence time vector, and jump to step S4.2; Among them, T su The value of the accelerated step length multiplied by the minimum iterative residence time is the accelerated iterative residence time vector; A o A is the material removal vector for all control points where iteration has not stopped; l is the material removal vector after the last iteration; A f It is the material removal vector of all control points that have not stopped iteration when iterating once with the minimum iteration residence time based on the cumulative iteration residence time; T s is the minimum iteration residence time vector; is the acceleration step length; S4.5: Calculate the remaining material removal amount of all control points, and use the non-negative least squares algorithm to calculate the residence time vector required for the polishing remaining material removal amount to obtain a non-negative least squares residence time vector; S4.6: The accumulated dwell time vector is added to the non-negative least square dwell time vector to obtain the final dwell time of each polishing point group.

5. A deterministic polishing device for shear thickening polishing, used to implement the deterministic polishing method as claimed in any one of claims 1 to 4, characterized in that: It comprises a stirring pool (1), a polishing pool (2), a powder injection module (3), a stirring module (4), a conveying module and a polishing processing module (5); A water injection pipe is provided on the water inlet of the stirring tank (1) for injecting a fixed amount of water into the stirring tank (1); The powder injection module (3) is arranged directly above the stirring tank (1) and is used to add a set weight of polishing liquid raw materials into the stirring tank (1), and stir the polishing liquid through the stirring module (4) to form the polishing liquid; The conveying module is used to convey the formed polishing liquid to the polishing pool (2) and the stirring pool (1) in sequence, thereby forming a flow circulation of the polishing liquid; The polishing processing module (5) is used to perform polishing processing on the workpiece to be processed in the polishing pool (2).

6. A deterministic polishing device for shear thickening polishing according to claim 5, characterized in that: The powder metering module (3) comprises a feeding component (3-1) and a weighing component (3-2); the weighing component (3-2) is installed in the forward direction of the feeding component (3-1) and can weigh the powder output by the feeding component (3-1) and dump it when a specified weight is reached; The feeding assembly (3-1) comprises a stepping motor (3-1-1), a screw (3-1-2) and a feeding base (3-1-3); the feeding base (3-1-3) is provided with a feeding trough and a powder transmission trough which are connected in sequence; the screw (3-1-2) is rotatably connected in the powder transmission trough and can be rotated under the drive of the stepping motor (3-1-1), thereby realizing the stepwise output of the powder falling into the powder transmission trough to the weighing assembly (3-2).

7. A deterministic polishing device for shear thickening polishing according to claim 6, characterized in that: The weighing assembly (3-2) comprises a supporting platform (3-2-1), and a feeding platform (3-2-2), an electronic scale (3-2-3) and an electric cylinder (3-2-4) mounted on the supporting platform (3-2-1); an end of the feeding platform (3-2-2) is rotatably connected to the supporting platform (3-2-1) and can be switched between a horizontal state and an inclined state under the drive of the electric cylinder (3-2-4); and the electronic scale (3-2-3) is fixed on the feeding platform (3-2-2).

8. A deterministic polishing device for shear thickening polishing according to claim 5, characterized in that: The stirring module (4) comprises a stirring paddle and a driving motor; the stirring paddle is rotatably connected to the stirring pool (1) and can be rotated under the drive of the driving motor, thereby stirring the injected water and the fallen powder to form a polishing liquid.

9. A deterministic polishing device for shear thickening polishing according to claim 5, characterized in that: The delivery module comprises two rotor pumps and two three-way valves; the two rotor pumps are divided into a first rotor pump (8) connected to the output end (11-3) of the stirring tank (1), and a second rotor pump (9) connected to the output end (11-3) of the polishing tank (2); the two three-way valves are divided into a first three-way valve (10) arranged on the pipeline between the first rotor pump (8) and the polishing tank (2); and a second three-way valve (11) arranged on the output end (11-3) of the second rotor pump (9); an online particle size analyzer (12) is arranged between the first rotor pump (8) and the first three-way valve (10) for real-time monitoring of the mixing and composition of the polishing liquid output from the stirring tank (1); The first three-way valve (10) and the second three-way valve (11) are provided with a first reflux pipe and a second reflux pipe respectively, which are used to be connected to the stirring tank (1).

Images