Time-space control grinding and polishing method and device for anisotropic thin-walled curved surface workpieces

Abstract

The present invention relates to a spatio-temporal control grinding and polishing method and device for anisotropic thin-walled curved surface workpieces, belonging to the field of ultra-precision polishing. The method fixes the anisotropic thin-walled curved surface workpiece on a multi-axis parallel motion platform; based on the machining postures of the flexible machining tools at each machining point and the machining crystal planes of the anisotropic thin-walled curved surface workpiece, calculates the spatial displacement regulation amount and material removal rate of the flexible machining tools at the machining points; based on the material removal rate and the target removal volume, deconvolves and calculates the dwell time of the flexible machining tools at the corresponding machining points; regulates the flexible machining tools based on the spatial displacement regulation amount and dwell time of the flexible machining tools, adaptively eliminates the removal differences under different machining postures and machining crystal planes of the anisotropic thin-walled curved surface workpiece, realizes high-precision controllable grinding and polishing, ensures a uniform material removal rate, realizes controllable material removal, fixes the workpiece by only constraining the boundary, and avoids stress deformation generated after the workpiece is separated from the tooling.

Description

Technical Field

[0001] The present invention belongs to the field of ultra-precision polishing, and particularly relates to a time-space controlled grinding and polishing method and device for anisotropic thin-walled curved surface workpieces. Background Art

[0002] Anisotropic thin-walled curved surface workpieces are widely used in the fields of automotive industry, aerospace, military, medical devices, shipbuilding, etc.; due to the special shape of anisotropic thin-walled curved surface workpieces, their surface quality directly affects their functions and appearances. Therefore, surface quality control is one of the key issues in the processing process. However, for such components, the characteristics of curvature change and material removal anisotropy result in different material removals for different machining postures and machining crystal planes during the machining process. There are still many difficulties in achieving the process requirements of controllable machining and high surface integrity.

[0003] Due to the material and structural characteristics of anisotropic thin-walled curved surface workpieces, traditional grinding wheel machining methods are extremely prone to workpiece fragmentation and uneven material removal. Therefore, currently, the traditional machining methods for anisotropic thin-walled curved surface workpieces are to remove materials by combining mechanical force and chemical modification, such as ultra-precision cutting, ion beam polishing, electron beam polishing, magnetorheological polishing and other grinding and polishing methods. In ultra-precision grinding, in order to adapt to the curvature change and thin-walled characteristics of the workpiece, one method is to completely fit the workpiece on the fixture for cutting with a fixed depth. Due to the hard contact, the fixture will apply residual stress to the workpiece, resulting in a surface shape change after the workpiece is detached from the fixture; similarly, due to the elastic recovery of the material after machining, this machining method still cannot avoid the machining differences of anisotropic materials on different machining crystal planes. Although non-contact machining methods such as ion beam polishing, electron beam polishing and magnetorheological polishing have sub-nanometer machining accuracy and can adapt to the curvature change and overloading and easy fragmentation characteristics of such workpieces, this method is usually used as the last process of machining. The reason is that the device of this machining method is expensive, the machining efficiency is low, and the material removal differences during the material removal process of anisotropic materials cannot be predicted.

[0004] Therefore, for the machining of anisotropic thin-walled curved surfaces, it is necessary to consider both the anisotropy of material loading deformation and removal and the curvature change at the machining point of the curved surface and the easy fragmentation characteristics of thin-walled materials. The flexible contact polishing method can deform the tool, can realize the flexible machining of the curved surface adaptively, avoid the easy fragmentation of overloaded materials, and the equipment is simple and has high-precision machining ability. However, the removal differences of anisotropic materials during polishing are still unpredictable, and stress deformation caused by hard fixture contact will still occur. Summary of the Invention

[0005] The object of the present invention is to provide a spatio-temporal control grinding and polishing method and device for anisotropic thin-walled curved surface workpieces, so as to solve the problems of anisotropic material removal during the processing of anisotropic thin-walled curved surface workpieces, easy fragmentation of thin-walled features, difficult machining of curved surfaces, and difficulty in conveniently achieving high-precision surface controllable forming.

[0006] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0007] The present invention relates to a spatio-temporal control grinding and polishing method for anisotropic thin-walled curved surface workpieces, which includes the following steps:

[0008] Measure the crystal orientation and crystal plane orientation of the anisotropic thin-walled curved surface workpiece, fix the anisotropic thin-walled curved surface workpiece on a multi-axis parallel motion platform, select the corresponding processing posture, and make the linear velocity direction of the flexible processing tool consistent with the crystal orientation of the processing point position of the anisotropic thin-walled curved surface workpiece;

[0009] Based on the processing posture of the flexible processing tool at each processing point and the processing crystal plane of the anisotropic thin-walled curved surface workpiece, calculate the spatial displacement regulation amount and material removal rate of the flexible processing tool at the processing point;

[0010] Based on the material removal rate and the target removal volume of the corresponding processing point, deconvolve and calculate the dwell time of the flexible processing tool at the corresponding processing point;

[0011] Based on the spatial displacement regulation amount and dwell time of the flexible processing tool at the corresponding processing point, regulate the flexible processing tool to adaptively eliminate the removal differences of the anisotropic thin-walled curved surface workpiece under different processing postures and processing crystal planes, and achieve high-precision controllable grinding and polishing.

[0012] Preferably, it includes the following steps:

[0013] S1: Detect the initial surface shape, crystal plane orientation and crystal orientation of the anisotropic thin-walled curved surface workpiece, fix the anisotropic thin-walled curved surface workpiece on a multi-axis parallel motion platform, and select the processing posture of the flexible processing tool at each processing point position based on the crystal orientation of the anisotropic thin-walled curved surface workpiece, so that the linear velocity direction of the flexible processing tool is consistent with the crystal orientation of the processing point position of the anisotropic thin-walled curved surface workpiece;

[0014] S2: Based on the contact pressure field distribution and processing crystal plane of the flexible processing tool in the target processing area, calculate the spatial displacement regulation amount required after the contact deformation between the flexible processing tool and the anisotropic thin-walled curved surface workpiece at each processing point;

[0015] S3: Set the target surface shape result, determine the target material removal volume based on the initial surface shape and the target surface shape, and calculate the material removal rate when the flexible machining tool removes material from the machining crystal plane in this machining posture in combination with the contact pressure field and the machining parameters;

[0016] S4: Calculate the dwell time of the flexible machining tool at each machining point in global grinding and polishing through deconvolution based on the target material removal volume and the material removal rate;

[0017] S5: Drive the flexible machining tool according to the spatial displacement adjustment amount and the dwell time of the flexible machining tool at each machining point, and then perform global grinding and polishing on the anisotropic thin-walled curved surface workpiece.

[0018] Preferably, in the S1, the anisotropic thin-walled curved surface workpiece is fixed on the multi-axis parallel motion platform by a fixed method that only restricts the boundary, and the fixed method of only restricting the boundary means that there is no support in the middle, and the edge is a fixed support, a simply supported support, a set boundary condition or a free clamping boundary.

[0019] Preferably, the displacement adjustment amount of the flexible machining tool in the S2 in the spatial domain The calculation formula is:

[0020] (1),

[0021] (2),

[0022] (3),

[0023] Among them, is the equivalent Young's modulus of the anisotropic thin-walled curved surface workpiece when the flexible machining tool removes material from the corresponding machining crystal plane, is the tool Poisson's ratio, and are the distance and azimuth angle between the calculation point and the pressure position respectively, is the equivalent radius of the flexible machining tool, represents the distance of the point in the pressure area from the machining point The distance of, is the pressure distribution of the machining point, is the displacement adjustment amount of the flexible machining tool set to ensure the uniform pressure field distribution considering the deformation of the workpiece and the tool, is the deformation of the flexible machining tool when machining the machining point , is the maximum deformation of the flexible machining tool, is the deformation of the anisotropic thin-walled curved surface workpiece at the position of the maximum deformation of the flexible machining tool.

[0024] Preferably, the material removal rate calculation formula of the flexible machining tool in S3 is:

[0025] (4),

[0026] (5),

[0027] (6),

[0028] wherein, is the yield limit of the machining crystal orientation, is the material removal rate of a single abrasive grain for material removal on the machining crystal plane, is the indentation depth of a single abrasive grain for material removal on the machining crystal plane, is the rotational speed of the flexible machining tool, is the material removal rate of all abrasive grains at the machining point, is the number of abrasive grains, is the set abrasive grain radius.

[0029] Preferably, the dwell time of the flexible machining tool that needs to be regulated in the time domain at each machining point in the global grinding and polishing in S4 has the following calculation formula:

[0030] (7),

[0031] wherein, is the machining time at the machining point ; is the target removal volume at the machining point ; is the deconvolution calculation symbol, is the pressure applied to the abrasive grains at the machining point .

[0032] Preferably, the maximum deformation of the flexible machining tool set in S2 is less than 20% of the thickness of the workpiece being machined.

[0033] Preferably, the pressure exerted by the flexible machining tool on the anisotropic thin-walled curved surface workpiece in S2 is not greater than 3 times the yield stress limit of the materials of the flexible machining tool and the machining crystal plane in the selected machining posture.

[0034] The present invention also relates to a time-space controlled grinding and polishing device for anisotropic thin-walled curved surface workpieces, which includes a multi-axis parallel motion platform, a controller, a calculator, and a flexible machining tool;

[0035] The multi-axis parallel motion platform is used to fix the anisotropic thin-walled curved surface workpiece and the flexible machining tool;

[0036] The described calculator calculates the spatial displacement adjustment amount and material removal rate of the flexible machining tool at the machining point based on the machining postures of the flexible machining tools at each machining point and the machining crystal planes of the anisotropic thin-walled curved surface workpiece, deconvolves the dwell time of the flexible machining tool at the corresponding machining point based on the material removal rate and the target removal volume at the corresponding machining point, and transmits the calculated spatial displacement adjustment amount and dwell time to the controller;

[0037] The described controller is used to drive the multi-axis parallel motion platform based on the spatial displacement adjustment amount and dwell time of the flexible machining tool at the corresponding machining point, so that the linear velocity direction of the machining of the flexible machining tool is consistent with the crystal direction of the machining point position of the anisotropic thin-walled curved surface workpiece, and at the same time, the controller adjusts the flexible machining tool to adaptively eliminate the removal differences of the anisotropic thin-walled curved surface workpiece under different machining postures and machining crystal planes, so as to achieve high-precision controllable grinding and polishing.

[0038] Preferably, the multi-axis parallel motion platform includes a base, an X-axis motion platform, a Y-axis motion platform, a fixing fixture, a frame, a cross beam, a Z-axis motion platform, and a rotating shaft. The flexible machining tool is fixed on the rotating shaft and is used for grinding and polishing the anisotropic thin-walled curved surface workpiece; the X-axis motion platform is connected above the base, the Y-axis motion platform is connected above the X-axis motion platform, the X-axis motion platform and the Y-axis motion platform are perpendicular to each other, the fixing fixture is installed on the Y-axis motion platform, and the fixing fixture is used for fixing the anisotropic thin-walled curved surface workpiece and realizing the linkage of the anisotropic thin-walled curved surface workpiece in the X-axis direction and the Y-axis direction through the X-axis motion platform and the Y-axis motion platform. The cross beam is installed on the base through the frame, the rotating shaft is installed on the cross beam, the Z-axis motion platform is installed on the rotating shaft, and the flexible machining tool is installed on the Z-axis motion platform, and the flexible machining tool is adjusted on the Z-axis and the machining angle is adjusted respectively through the Z-axis motion platform and the rotating shaft.

[0039] The described flexible machining tool adopts flexible tools such as air bags.

[0040] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0041] 1. The time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces according to the present invention is based on the machining postures of flexible machining tools at each machining point and the machining crystal planes of anisotropic thin-walled curved surface workpieces, calculates the spatial displacement control amount and material removal rate of the flexible machining tool at the machining point, and then calculates the dwell time of the flexible machining tool at the corresponding machining point by deconvolving the material removal rate and the target removal volume of the corresponding machining point. The spatial displacement control amount and dwell time are used to control the flexible machining tool to achieve controllable grinding and polishing. In the spatial domain, this method can adapt to the differences in the loading and deformation of anisotropic materials on different crystal planes, maintain a stable contact pressure field distribution in the entire domain, and thus ensure a uniform material removal rate. In the time domain, by adjusting the machining time, it can adapt to the material removal differences of anisotropic materials during the machining process and achieve controllable material removal.

[0042] 2. During the grinding and polishing process of the time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces according to the present invention, the anisotropic thin-walled curved surface workpiece is fixed on the tooling by only constraining the boundary, avoiding the stress deformation generated after the workpiece is separated from the tooling, and making the processed surface shape more accurate.

[0043] 3. The flexible machining tool is used in the grinding and polishing process of the time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces. The flexible machining tool can adapt to the machining difficulties of the curved surface of anisotropic thin-walled curved surface workpieces and the problem that the thin-walled features are easily broken. Brief Description of the Drawings

[0044] Figure 1 is a schematic structural diagram of a multi-axis parallel motion platform for implementing the time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces according to the present invention;

[0045] Figure 2 is a flow chart of the time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces;

[0046] Figure 3 is a schematic diagram of the fixing method of an anisotropic thin-walled curved surface workpiece;

[0047] Figure 4 is a schematic diagram of the spatial displacement control of the machining tool on different crystal planes;

[0048] Figure 5 is a schematic diagram of the machining time displacement control under different crystal planes and different machining postures.

[0049] In the figure: 1 - base, 2 - X-axis motion platform, 3 - Y-axis motion platform, 4 - fixing tooling, 5 - frame, 6 - cross beam, 7 - Z-axis motion platform, 8 - rotating shaft, 9 - flexible machining tool, 10 - controller, 11 - calculator. Detailed Embodiments

[0050] The technical solution of the present invention will be further specifically described below through specific embodiments. The embodiments are for the purpose of illustrating the present invention and not for limiting it. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0051] A spatio-temporal control grinding and polishing method for anisotropic thin-walled curved surface workpieces according to the present invention fixes the anisotropic thin-walled curved surface workpieces on a fixed fixture by only constraining the boundary; in the spatial domain, calculates the spatial displacement adjustment amount of the flexible machining tool at the machining point; calculates the material removal rate of the flexible machining tool in the machining posture; in the time domain, based on the material removal rate and the target removal volume at the machining point, deconvolves to calculate the dwell time of the flexible machining tool at each machining point; based on the spatial displacement adjustment amount and the dwell time of the flexible machining tool at the machining point, drives the flexible machining tool to move through a multi-axis parallel motion platform, adaptively eliminates the removal differences under different machining postures and machining crystal planes of the anisotropic thin-walled curved surface workpieces, and realizes high-precision controllable grinding and polishing. The specific structure of the spatio-temporal control grinding and polishing device for anisotropic thin-walled curved surface workpieces is as Figure 1 shown, including a multi-axis parallel motion platform, a controller, a calculator and a flexible machining tool; the multi-axis parallel motion platform is used to fix the anisotropic thin-walled curved surface workpieces and the flexible machining tool 9; the calculator 11 calculates the spatial displacement adjustment amount and the material removal rate of the flexible machining tool at the machining point based on the machining posture of the flexible machining tool at each machining point and the machining crystal plane of the anisotropic thin-walled curved surface workpiece, deconvolves based on the material removal rate and the target removal volume at the corresponding machining point to calculate the dwell time of the flexible machining tool at the corresponding machining point, and transmits the calculated spatial displacement adjustment amount and dwell time to the controller; the controller 10 is used to drive the multi-axis parallel motion platform based on the spatial displacement adjustment amount and the dwell time of the flexible machining tool at the corresponding machining point, so that the linear velocity direction of the machining of the flexible machining tool is consistent with the crystal direction of the machining point position of the anisotropic thin-walled curved surface workpiece, and at the same time, adjusts the flexible machining tool to adaptively eliminate the removal differences of the anisotropic thin-walled curved surface workpiece under different machining postures and machining crystal planes, and realizes high-precision controllable grinding and polishing.

[0052] The above-mentioned multi-axis parallel motion platform includes a base 1, an X-axis motion platform 3, a Y-axis motion platform 2, a fixing fixture 4, a frame 5, a cross beam 6, a Z-axis motion platform 7, and a rotating shaft 8. The flexible machining tool 9 is fixed on the rotating shaft 8 and is used for grinding and polishing anisotropic thin-walled curved surface workpieces. The X-axis motion platform 3 is connected above the base 1, and the Y-axis motion platform 2 is connected above the X-axis motion platform 3. The X-axis motion platform 3 and the Y-axis motion platform 2 are perpendicular to each other. The fixing fixture 4 is installed on the Y-axis motion platform 2 and is used for fixing the anisotropic thin-walled curved surface workpiece, and realizes the linkage of the anisotropic thin-walled curved surface workpiece in the X-axis direction and the Y-axis direction through the X-axis motion platform and the Y-axis motion platform. The fixing method of the anisotropic thin-walled curved surface workpiece is a fixing method that only restricts the boundary. The fixing method that only restricts the boundary means that there is no support in the middle, and the edges are fixed supports, simply supported, conditional boundaries or free clamping boundaries. The cross beam 6 is installed on the base 1 through the frame 5, the rotating shaft 8 is installed on the cross beam 6, the Z-axis motion platform 7 is installed on the rotating shaft 8, and the flexible machining tool 9 is installed on the Z-axis motion platform 7. The adjustment of the flexible machining tool 9 in the Z-axis and the adjustment of the machining angle are realized through the Z-axis motion platform 7 and the rotating shaft 8 respectively.

[0053] Refer to the appendix Figure 2 The time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces specifically includes the following steps:

[0054] S0: Determine the processing parameters and the parameters of the anisotropic thin-walled curved surface workpiece, including the radius, Young's modulus, Poisson's ratio, processing speed, processing attitude, workpiece thickness, curvature change, processing crystal plane, polishing liquid particle size and concentration, etc.

[0055] S1: Detect the initial surface shape, crystal plane orientation and crystal orientation of the anisotropic thin-walled curved surface workpiece, and fix the anisotropic thin-walled curved surface workpiece on the fixing fixture of the multi-axis parallel motion platform by the method of only restricting the boundary. As Figure 3 shown, the fixing method of the anisotropic thin-walled curved surface workpiece is that there is no support in the middle, and the edges are fixed supports, simply supported, conditional boundaries or free clamping boundaries; select the processing attitude of the flexible machining tool at the position of each processing point based on the crystal orientation of the anisotropic thin-walled curved surface workpiece, so that the linear velocity direction of the machining of the flexible machining tool is consistent with the crystal orientation of the processing point position of the anisotropic thin-walled curved surface workpiece;

[0056] S2: Refer to the appendix Figure 4As shown in the figure, set the contact pressure field distribution of the flexible machining tool for the target machining area and the machining crystal plane. Based on the contact pressure field distribution, the material and structural parameters of the anisotropic thin-walled curved surface workpiece, calculate the spatial displacement adjustment amount that needs to be adjusted in the spatial domain after the flexible machining tool contacts and deforms with the anisotropic thin-walled curved surface workpiece at each machining point, so as to compensate for the uneven pressure field distribution caused by the deformation of the thin-walled workpiece. In this step, the pressure exerted by the flexible machining tool on the anisotropic thin-walled curved surface workpiece shall not be greater than 3 times the yield stress limit of the machining attitude and the machining crystal plane material, and the deformation generated by the flexible machining tool acting on the workpiece shall be within the elastic deformation range, that is, the maximum deformation is less than 20% of the thickness of the machined workpiece;

[0057] Spatial displacement adjustment amount of the flexible machining tool The calculation formula is:

[0058] (1),

[0059] (2),

[0060] (3),

[0061] Among them, is the equivalent Young's modulus of the anisotropic thin-walled curved surface workpiece when the flexible machining tool removes material on the corresponding machining crystal plane, is the Poisson's ratio of the tool, and are the distance and azimuth angle between the calculation point and the pressure position respectively, is the equivalent radius of the flexible machining tool, represents the distance of the point within the pressure area from the machining point of, is the pressure distribution at the machining point, is the displacement adjustment amount of the flexible machining tool set to ensure a uniform pressure field distribution considering the deformation of the workpiece and the tool, is the machining point When machining, the deformation of the flexible machining tool, is the maximum deformation of the flexible machining tool, is the deformation of the anisotropic thin-walled curved surface workpiece at the position of the maximum deformation of the flexible machining tool.

[0062] S3: Refer to the appendix Figure 5 As shown in the figure, set the target surface shape result. Based on the initial surface shape and the target surface shape, determine the target material removal volume H. Calculate the material removal rate of the flexible machining tool when removing material on this machining crystal plane according to the initial surface shape, the contact pressure field and the machining parameters (such as machining attitude and machining crystal plane, polishing liquid concentration, polishing liquid particle size, etc.). The calculation formula is:

[0063] (4),

[0064] (5),

[0065] (6),

[0066] wherein is the yield limit of the processing crystal orientation, is the material removal rate of a single abrasive grain for material removal on the processing crystal plane, is the indentation depth of a single abrasive grain for material removal on the processing crystal plane, is the rotational speed of the flexible processing tool, is the material removal rate of all abrasive grains at the processing point, is the set abrasive grain radius.

[0067] S4: Calculate the dwell time of the flexible processing tool that needs to be regulated in the time domain at each processing point in the global grinding and polishing based on the target material removal volume and the material removal rate , to compensate for the material removal differences of different crystal planes and crystal orientations of different anisotropic thin-walled curved surface workpieces. The calculation formula is:

[0068] (7),

[0069] wherein, is the processing time at the processing point , is the target removal volume at is the deconvolution calculation symbol, is the pressure applied to the abrasive grains at the processing point .

[0070] S5: The calculator constructs a spatio-temporal regulation cloud map based on the spatial displacement regulation amount of the flexible processing tool in the spatial domain and the dwell time of the flexible processing tool in the time domain. The controller starts the multi-axis parallel motion platform according to the spatio-temporal regulation cloud map, so that the multi-axis parallel motion platform drives the flexible processing tool according to the spatial displacement regulation amount of the flexible processing tool in the spatial domain and the dwell time of the flexible processing tool in the time domain at each processing point, and then performs global grinding and polishing on the anisotropic thin-walled curved surface workpiece.

[0071] In this article, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces, characterized in that: It includes the following steps: Measure the crystal orientation and crystal plane orientation of the anisotropic thin-walled curved surface workpiece, fix the anisotropic thin-walled curved surface workpiece on the multi-axis parallel motion platform, select the corresponding machining posture, and make the linear velocity direction of the flexible machining tool consistent with the crystal orientation at the machining point position of the anisotropic thin-walled curved surface workpiece; Based on the machining postures of the flexible machining tools at each machining point and the machining crystal planes of the anisotropic thin-walled curved surface workpiece, calculate the spatial displacement adjustment amount and material removal rate of the flexible machining tools at the machining points; the displacement adjustment amount of the flexible machining tools in the spatial domain The calculation formula is as follows: (1)， (2)， (3)， Among them, is the equivalent Young's modulus of the anisotropic thin-walled curved surface workpiece when the flexible machining tool removes materials on the corresponding machining crystal plane, is the Poisson's ratio of the tool, and are the distance and azimuth angle between the calculation point and the pressure position respectively, is the equivalent radius of the flexible machining tool, represents the distance of the point in the pressure area from the machining point , is the pressure distribution at the machining point, is the displacement regulation amount of the flexible machining tool set to ensure the uniform pressure field distribution considering the deformation of the workpiece and the tool, is the deformation of the flexible machining tool when machining the machining point , is the maximum deformation of the flexible machining tool, is the deformation of the anisotropic thin-walled curved surface workpiece at the position of the maximum deformation of the flexible machining tool; Based on the material removal rate and the target removal volume of the corresponding machining point, deconvolve and calculate the dwell time of the flexible machining tool at the corresponding machining point; Based on the spatial displacement adjustment amount and dwell time of the flexible machining tool at the corresponding machining point, adjust the flexible machining tool to adaptively eliminate the removal differences of the anisotropic thin-walled curved surface workpiece under different machining postures and machining crystal planes, and achieve high-precision controllable grinding and polishing.

2. The time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces according to claim 1, characterized in that: It includes the following steps: S1: Detect the initial surface shape, crystal plane orientation and crystal orientation of the anisotropic thin-walled curved surface workpiece, fix the anisotropic thin-walled curved surface workpiece on the multi-axis parallel motion platform, and select the machining posture of the flexible machining tool at each machining point position based on the crystal orientation of the anisotropic thin-walled curved surface workpiece, so that the linear velocity direction of the flexible machining tool is consistent with the crystal orientation at the machining point position of the anisotropic thin-walled curved surface workpiece; S2: Calculate the required spatial displacement adjustment amount after the contact deformation between the flexible machining tool and the anisotropic thin-walled curved surface workpiece at each machining point based on the contact pressure field distribution and machining crystal plane of the flexible machining tool in the target machining area; S3: Set the target surface shape result, determine the target material removal volume based on the initial surface shape and the target surface shape, and calculate the material removal rate of the flexible machining tool when removing material from this machining crystal plane in this machining posture in combination with the contact pressure field and machining parameters; S4: Based on the target material removal volume and the material removal rate, calculate the dwell time of the flexible machining tool at each machining point in the global grinding and polishing through deconvolution; S5: Drive the flexible machining tool according to the spatial displacement adjustment amount and dwell time of the flexible machining tool at each machining point, and then perform global grinding and polishing treatment on the anisotropic thin-walled curved surface workpiece.

3. The time-space controlled grinding and polishing method for anisotropic thin-walled curved surface workpieces according to claim 2, characterized in that: In the above S1, the anisotropic thin-walled curved surface workpiece is fixed on the multi-axis parallel motion platform by a fixed method that only restricts the boundary. The fixed method that only restricts the boundary means that there is no support in the middle, and the edge is a fixed support, simply supported, conditional boundary or free clamping boundary.

4. The time-space controlled grinding and polishing method for anisotropic thin-walled curved surface workpieces according to claim 2, wherein: The formula for calculating the material removal rate of the flexible machining tool in the above S3 is: (4)， (5)， (6)， Among them, is the yield limit of the processing crystal orientation, is the material removal rate of a single abrasive grain for material removal on the processing crystal plane, is the indentation depth of a single abrasive grain for material removal on the processing crystal plane, is the rotational speed of the flexible processing tool, is the material removal rate of all abrasive grains at the processing point, is the number of abrasive grains, is the radius of the set abrasive grain.

5. The time-space controlled grinding and polishing method for anisotropic thin-walled curved surface workpieces according to claim 4, wherein: The dwell time of the flexible machining tool that needs to be regulated in the time domain at each machining point during global grinding in S4 The calculation formula is as follows: (7)， wherein, is the processing time at the processing point , is the target removal volume at the processing point , is the deconvolution calculation symbol is the pressure applied to the abrasive grains at the processing point .

6. The time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces according to claim 2, characterized in that: In the above S2, it is set that the maximum deformation of the flexible machining tool is less than 20% of the thickness of the workpiece being machined.

7. The time-space control grinding and polishing method for anisotropic thin-walled curved surface workpieces according to claim 2, wherein: In the above S2, it is set that the pressure exerted by the flexible machining tool on the anisotropic thin-walled curved surface workpiece is not greater than 3 times the yield stress limit of the flexible machining tool and the machining crystal plane material in the selected machining posture.

8. A time-space controlled grinding and polishing device for anisotropic thin-walled curved surface workpieces, characterized in that: It includes a multi-axis parallel motion platform, a controller, a calculator and a flexible machining tool; The above multi-axis parallel motion platform is used to fix the anisotropic thin-walled curved surface workpiece and the flexible machining tool; The described calculator calculates the spatial displacement adjustment amount and material removal rate of the flexible machining tool at the machining point based on the machining postures of the flexible machining tools at each machining point and the machining crystal planes of the anisotropic thin-walled curved surface workpiece, deconvolves and calculates the dwell time of the flexible machining tool at the corresponding machining point based on the material removal rate and the target removal volume of the corresponding machining point, and transmits the calculated spatial displacement adjustment amount and dwell time to the controller; the displacement adjustment amount of the flexible machining tool in the spatial domain The calculation formula is as follows: (1)， (2)， (3)， Among them, is the equivalent Young's modulus of the anisotropic thin-walled curved surface workpiece when the flexible machining tool removes materials on the corresponding machining crystal plane, is the Poisson's ratio of the tool, and are respectively the distance and azimuth angle between the calculation point and the pressure position, is the equivalent radius of the flexible machining tool, represents the distance of the point within the pressure area from the machining point , is the pressure distribution at the machining point, is the displacement regulation amount of the flexible machining tool set to ensure the uniform pressure field distribution considering the deformation of the workpiece and the tool, is the deformation of the flexible machining tool when machining the machining point , is the maximum deformation of the flexible machining tool, is the deformation of the anisotropic thin-walled curved surface workpiece at the position of the maximum deformation of the flexible machining tool; The described controller is used to drive the multi-axis parallel motion platform based on the spatial displacement regulation amount and dwell time of the flexible machining tool at the corresponding machining point, so that the linear velocity direction of the machining by the flexible machining tool is consistent with the crystal orientation of the machining point position of the anisotropic thin-walled curved surface workpiece. At the same time, the flexible machining tool is regulated to adaptively eliminate the removal differences of the anisotropic thin-walled curved surface workpiece under different machining postures and machining crystal planes, realizing high-precision controllable grinding and polishing.

9. The time-space controlled grinding and polishing device for anisotropic thin-walled curved surface workpieces according to claim 8, characterized in that: The described multi-axis parallel motion platform includes a base, an X-axis motion platform, a Y-axis motion platform, a fixing fixture, a frame, a cross beam, a Z-axis motion platform, and a rotating shaft. The flexible machining tool is fixed on the rotating shaft and is used for grinding and polishing the anisotropic thin-walled curved surface workpiece. The X-axis motion platform is connected above the base, and the Y-axis motion platform is connected above the X-axis motion platform. The X-axis motion platform and the Y-axis motion platform are perpendicular to each other. The fixing fixture is installed on the Y-axis motion platform and is used to fix the anisotropic thin-walled curved surface workpiece, and realizes the linkage of the anisotropic thin-walled curved surface workpiece in the X-axis direction and the Y-axis direction through the X-axis motion platform and the Y-axis motion platform. The cross beam is installed on the base through the frame, the rotating shaft is installed on the cross beam, the Z-axis motion platform is installed on the rotating shaft, and the flexible machining tool is installed on the Z-axis motion platform, and realizes the adjustment of the flexible machining tool on the Z-axis and the adjustment of the machining angle through the Z-axis motion platform and the rotating shaft respectively.

Images