Method for processing a large-diameter sheet metal part

Abstract

The application discloses a metal large-diameter thin plate part machining method and relates to the technical field of grinding and polishing. The method realizes efficient and low-stress thinning by electrochemical grinding of the thin plate, and converts the irregular surface shape of the workpiece into a central symmetric surface shape. Then, the surface shape error is controlled by a chemical mechanical grinding method with surface shape prediction capability, so that the surface shape error of the thin plate is reduced, over-processing is avoided, and resources are saved. In addition, only a general single-side grinding and polishing machine is needed, and the work disc diameter d1 and the thin plate diameter d2 satisfy d2 < d1 <= 2d2, so that the large-diameter thin plate part obtains micron-level surface shape precision, and the equipment cost is reduced. Finally, the electrochemical mechanical polishing realizes high surface quality machining of the thin plate, and on the basis that the surface shape precision is not obviously deteriorated, the surface quality of the machined surface is greatly improved. The application overcomes the problem that the metal large-diameter thin plate is sensitive to force and thermal load, and realizes high surface shape precision and high surface quality machining of the metal large-diameter thin plate.

Description

Technical Field

[0001] This invention relates to the field of grinding and polishing technology, specifically to a method for processing large-diameter thin metal sheet parts with high surface accuracy and high surface quality. Background Technology

[0002] Thin metal sheet parts are common engineering products widely used in fields such as electronics and information technology, aerospace, defense, energy and transportation, and materials engineering. To meet the performance requirements of these fields, precision or ultra-precision machining is often necessary to achieve the required machining quality. Some precision physics experiments, such as detonation wave collision experiments and fly-layer impact experiments, require thin metal sheets with a diameter of Φ100~Φ200mm, a thickness of 2.2~3mm, a flatness PV≤2μm, and a surface roughness R. a The requirement is ≤5nm. However, when machining thin sheet parts made of different materials, the machining method and the non-uniformity of material removal from the part surface can affect the machining quality. In addition, thin sheet metal parts generally have poor rigidity. Due to the influence of various factors such as blank internal stress, tooling clamping force, cutting force and cutting heat during machining, and residual stress on the machined surface, thin sheet parts often exhibit machining deformations such as warping, bending, and twisting, which are complex and diverse, seriously affecting the machining accuracy. Therefore, in the field of mechanical manufacturing, machining thin sheet parts with high surface accuracy and high surface quality has always been a challenge.

[0003] Currently, the main method for machining thin metal sheets with high surface accuracy and quality is mechanical machining, primarily employing cutting processes such as turning and ultra-precision flying shear. However, due to the weak rigidity of thin sheet structures, thin sheet parts are extremely sensitive to force. Using traditional machining methods on thin sheet parts can easily lead to warping, edge collapse, and other deformations, making it difficult to guarantee surface accuracy. When machining pure copper thin sheets using other methods such as mechanical grinding and lapping, the grinding wheel is prone to chip adhesion and clogging, resulting in unstable grinding wheel conditions and difficulty maintaining a constant material removal rate (MRR). Furthermore, as machining time increases, the degree of grinding wheel clogging worsens, causing the MRR to gradually decrease and ultimately leading to grinding wheel failure.

[0004] Other specialized composite processing technologies based on multiple chemical and electrochemical fields, such as chemical mechanical polishing (CMP), electrochemical polishing (ECP), electrochemical polishing (ECP), and electrochemical mechanical polishing (ECMP), can significantly weaken or suppress the negative impact of force during processing by utilizing the synergistic effects of chemistry, electrochemistry, and mechanics. However, due to inherent technological limitations, it is difficult to simultaneously achieve high surface accuracy and high surface quality. CMP generates easily removable substances through a chemical reaction on the workpiece surface, which are then removed using a polishing pad or abrasive particles. This can achieve sub-nanometer roughness on pure copper surfaces. However, the deformation of the polishing pad during material removal can increase surface shape errors in thin pure copper plates. Electrochemical polishing can achieve nanometer-level roughness in pure copper and offers the advantage of stress-free processing, but stray current corrosion can easily increase surface shape errors. Electrochemical polishing (ECP) achieves higher etchant concentrations at localized high points on the metal part's surface, resulting in a higher removal rate and stress-free removal of these high points, thus smoothing the machined surface. However, its maximum etchant removal rate (MRR) is limited. For static machining of thin pure copper plates (workpiece stationary relative to the electrode), the MRR is 0.107 μm / h, while for dynamic machining (workpiece rotating relative to the electrode), the MRR is 0.618–0.756 μm / h. Electrochemical mechanical polishing (EMF) generates a passivation film on the metal part's surface through an electrochemical reaction to inhibit electrolysis. The high points of the passivation film are then removed by the friction of the abrasive, avoiding direct contact between the workpiece surface and the abrasive grains. However, the currently used high polishing pressure (P ≥ 0.8 psi) may introduce stress when the abrasive grains scratch the thin-walled metal surface, leading to increased surface shape errors and making it difficult to meet machining quality requirements.

[0005] In summary, current research on machining large-diameter thin-plate metal parts with high surface accuracy and high surface quality still faces the following challenges:

[0006] 1. Due to the sensitivity of the thin sheet structure to force, the large diameter thin sheet metal is easily deformed by stress introduced into the surface layer during machining, which increases the surface shape error.

[0007] 2. Existing special processing technologies are difficult to directly meet the processing quality requirements of large-diameter thin metal plates. Summary of the Invention

[0008] In view of this, the present invention provides a machining process for large-diameter thin metal sheet parts. This process, through a combination of chemical / electrochemical and mechanical actions, achieves efficient and low-stress thinning of large-diameter thin metal sheets, surface shape error control, and surface quality improvement in three stages. It provides a new technology for machining large-diameter thin sheets with high surface shape accuracy and high surface quality.

[0009] Therefore, the present invention provides the following technical solution:

[0010] The present invention provides a method for machining a large-diameter thin metal plate part, and the method includes: electrochemically grinding a to-be-machined metal plate according to high-potential and low-pressure electrochemical grinding parameters to obtain a large-diameter thin metal plate workpiece after thinning and surface shape transformation;

[0011] Controlling the surface shape error of the workpiece by a chemical mechanical grinding method based on pressure and speed regulation, and specifically adjusting the distribution of surface material removal amount;

[0012] Performing low-pressure electrochemical mechanical polishing on the large-diameter thin metal plate after surface shape error control.

[0013] Further, electrochemically grinding the to-be-machined metal plate according to high-potential and low-pressure electrochemical grinding parameters includes:

[0014] Using a hydroxyethylidene diphosphonic acid-based electrolyte to generate a corrosion inhibition film to replace the passivation film to protect the metal surface at a limiting current plateau potential higher than the passivation region, and coupling with the abrasive friction of a diamond固结磨料垫(此处原文有误,推测为固结磨料垫diamond固结磨料垫应改为diamond固结磨料垫) to perform electrochemical grinding at a low grinding pressure.

[0015] Further, the composition of the hydroxyethylidene diphosphonic acid-based electrolyte includes: 5-10 wt% of hydroxyethylidene diphosphonic acid, 0.1-0.5 wt% of methylbenzotriazole, 1-5 wt% of ammonium citrate, 3-6 wt% of potassium hydroxide, and deionized water; the pH of the hydroxyethylidene diphosphonic acid-based electrolyte is 8-9.

[0016] Further, controlling the surface shape error of the workpiece by a chemical mechanical grinding method based on pressure and speed regulation includes:

[0017] Processing the initial surface shape of the workpiece to obtain a centrosymmetric convex surface shape or a centrosymmetric concave surface shape;

[0018] Establishing a large-diameter thin plate surface shape prediction model considering the influence of pressure and speed distribution on material removal amount for the surface shape of the workpiece after processing;

[0019] Determining the chemical mechanical grinding motion parameters, and the motion parameters include: eccentricity, workpiece rotation speed, and grinding pad revolution speed; when facing a convex surface shape, adjusting the eccentricity to the range of e > r1 - r2 for chemical mechanical grinding; when facing a concave surface shape, adjusting the eccentricity to the range of e < r2 for chemical mechanical grinding. When e is lower than the workpiece radius r2 and approaches zero, the relative speed at the edge of the metal thin plate is higher than that at the center, so that the material removal amount at the edge is higher than that at the center; where e represents the eccentricity, r1 represents the radius of the grinding pad, and r2 represents the radius of the workpiece;

[0020] 注:原文中“diamond固结磨料垫”可能有误,已按推测修正为“diamond固结磨料垫应改为diamond固结磨料垫”,实际翻译时请根据准确内容调整。Based on the surface shape prediction model and the motion parameters, obtain the relationship between the predicted surface shape error and the processing time. Based on the relationship between the predicted surface shape error and the processing time, determine the processing time of the workpiece;

[0021] Process the workpiece according to the motion parameters and the processing time.

[0022] Furthermore, process the initial surface shape of the workpiece to obtain a centrosymmetric convex surface shape or a centrosymmetric concave surface shape, including:

[0023] If the initial surface shape of the workpiece is a centrosymmetric convex surface shape or a concave surface shape, no processing is required;

[0024] If the initial surface shape of the workpiece is a non-centrosymmetric surface shape, select the chemical mechanical polishing motion parameters according to the overall convexity and concavity of the surface shape. For a workpiece with an overall convex surface shape, use e > r1 - r2 for chemical mechanical polishing to transform it into a centrosymmetric concave surface shape; for a workpiece with an overall concave surface shape, use e < r2 for chemical mechanical polishing to transform it into a centrosymmetric concave surface shape.

[0025] Furthermore, establish a large-diameter thin plate surface shape prediction model considering the influence of pressure and velocity distribution on the material removal amount, including:

[0026] Obtain the material removal amount at any point on the processed surface by multiplying the material removal rate by the processing time T; the material removal rate is the product of the Preston coefficient k, the pressure P between the workpiece and the grinding tool, and the absolute value V of the relative velocity;

[0027] Obtain the material removal amount distribution in the whole region by multiplying the pressure distribution in the whole region between the workpiece and the grinding tool, the distribution of the absolute value V of the relative velocity, the Preston coefficient k, and the processing time T;

[0028] Calculate the pressure distribution in the whole region between the workpiece and the grinding tool;

[0029] Calculate the absolute value of the relative velocity at any point in the contact region between the workpiece and the polishing pad to obtain the distribution of the absolute value of the relative velocity in the whole region between the workpiece and the grinding tool;

[0030] Assume that the Preston coefficient k is a constant value to obtain the instantaneous material removal amount distribution, and then combine the actual surface shape results in the calibration test to calibrate the Preston coefficient k through the one-dimensional search and trial method;

[0031] After obtaining the instantaneous material removal amount distribution of the workpiece by multiplying the Preston coefficient k, the pressure distribution in the whole region between the workpiece and the grinding tool, and the distribution of the absolute value of the relative velocity in the whole region between the workpiece and the grinding tool, obtain the material removal amount in the whole region within the rotation period of the workpiece according to the rotation speed of the workpiece;

[0032] The predicted surface shape of the workpiece is obtained by subtracting the total material removal amount from the initial surface shape of the workpiece.

[0033] Furthermore, the large-diameter thin metal plate, after surface shape error control, undergoes low-pressure electrochemical mechanical polishing, including:

[0034] Select the electrolyte based on the initial surface roughness, for roughness R a For surfaces with a roughness greater than 350nm, electrochemical mechanical polishing of thin sheet parts was first performed using a thiosalicylic acid-based electrolyte at a working pressure P ≤ 0.3psi. Processing parameters were selected using the coefficient of variation method to reduce the workpiece roughness to R0.3. a ≤30nm, then electrochemical mechanical polishing of thin plate parts was performed using glycine-phenyltriazole electrolyte at a low polishing pressure P≤0.3psi. Processing parameters were selected using the coefficient of variation method to reduce the roughness R. a ≤5nm; for roughness R a Surfaces with a diameter of ≤350nm are directly polished using a glycine-phenyltriazole electrolyte.

[0035] The components of the thiosalicylic acid-based electrolyte include: 1-10 wt% glycine, 1.1-1.5 wt% thiosalicylic acid, 1-5 wt% polyethylene glycol, 1-9 wt% silica sol, 1-5 wt% potassium hydroxide and deionized water, and the pH of the thiosalicylic acid-based electrolyte is 8.5.

[0036] The glycine-phenyltriazole electrolyte comprises: 3.5-4 wt% glycine, 1-1.5 wt% phenyltriazole, 2-2.5 wt% potassium hydroxide, 2-3 wt% silica sol with a particle size of 50 nm and deionized water, and the pH of the glycine-phenyltriazole electrolyte is 8.5.

[0037] Furthermore, when e>r1-r2, the pressure distribution between the workpiece and the grinding wheel is characterized by a linear distribution along the workpiece's edge direction throughout the entire region, and the slope of the pressure distribution function increases with the edge distance.

[0038] Furthermore, the grinding pad is a bonded abrasive pad, and the grinding fluid is an acidic grinding fluid based on persulfate.

[0039] Furthermore, the diameter of the large-diameter thin plate part is Φ50~Φ220mm, the thickness is 1.5~4mm, and the diameter-to-thickness ratio is ≥20.

[0040] Advantages and positive effects of the present invention:

[0041] 1. Achieve high surface accuracy and high surface quality machining of large-diameter thin metal plates, overcoming the sensitivity of planar weak rigid components to force and thermal loads.

[0042] 2. At the limiting current level potential above the passivation potential, electrochemical polishing can reduce the material removal rate, thin the workpiece, reduce roughness, and improve processing efficiency.

[0043] 3. In electrochemical polishing, the edges of the workpiece are at a high potential due to the tip effect at sharp points, resulting in a higher material removal rate compared to other areas. Furthermore, the negative correlation between the electrode spacing between the workpiece and the counter electrode and the material removal rate allows irregular workpiece shapes to be transformed into centrally symmetric shapes. Additionally, if the initial workpiece shape is centrally symmetric, the surface accuracy of the workpiece will not significantly deteriorate during the thinning process.

[0044] 4. Reduced equipment costs: The chemical mechanical polishing method in this invention does not require the working disc diameter of the polishing machine to be ≥2 times the diameter of the thin plate, and it does not require a high-precision polishing machine. A general single-sided polishing machine is sufficient to achieve micron-level surface accuracy for large-diameter thin plate parts, which greatly reduces equipment costs.

[0045] 5. It provides strong guidance in the process of surface shape error control, which is conducive to improving processing efficiency. After inputting the initial surface shape data of the workpiece, the relationship between the surface shape error of the workpiece and the processing time can be obtained within 5 minutes. The optimal processing time for the corresponding minimum surface shape error can be obtained, avoiding over-processing and saving resources.

[0046] 6. In electrochemical mechanical polishing, a significant improvement in surface quality is achieved without a substantial deterioration in surface shape accuracy. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram illustrating the principle of electrochemical grinding / electrochemical mechanical polishing in an embodiment of the present invention;

[0049] Figure 2 This diagram illustrates a surface shape error control strategy based on chemical mechanical polishing for centrally symmetrical convex and concave surface shapes in an embodiment of the present invention.

[0050] Figure 3 This is a schematic diagram illustrating the calculation principle of the surface shape prediction model in an embodiment of the present invention.

[0051] Figure 4 This is a schematic diagram illustrating the pressure distribution calculation between the workpiece with protruding edge and the grinding pad in an embodiment of the present invention;

[0052] Wherein, O1 is the center of the grinding pad; O2 is the center of the workpiece; C is the point where the edge of the grinding pad coincides with the surface of the workpiece; A is the intersection of C along the negative x1 axis with the edge of the workpiece; B is the intersection of AC and the y2 axis; D is the intersection of C along the positive x1 axis with the edge of the workpiece; w1 is the revolution speed of the grinding pad; w2 is the rotation speed of the workpiece.

[0053] Figure 5 This is a flowchart illustrating the calculation process of the surface shape prediction model in an embodiment of the present invention.

[0054] Figure 6 This is a flowchart illustrating the surface error control in an embodiment of the present invention;

[0055] Figure 7 This is a flowchart of a method for processing large-diameter thin metal plate parts according to an embodiment of the present invention;

[0056] Figure 8 R before electrochemical polishing in this embodiment of the invention a Schematic diagram of 607.0nm;

[0057] Figure 9 In this embodiment of the invention, R is obtained after electrochemical grinding for 10 minutes. a Schematic diagram of 162.4nm;

[0058] Figure 10 This is a schematic diagram illustrating the relationship between workpiece flatness and electrochemical grinding time in an embodiment of the present invention;

[0059] Figure 11 This is a schematic diagram of the initial PV of 49.6 μm in an embodiment of the present invention;

[0060] Figure 12 This is a schematic diagram showing the PV of 49.2 μm after 90 min of electrochemical grinding in an embodiment of the present invention;

[0061] Figure 13 This is a schematic diagram showing the PV of 48.5 μm after 150 min of electrochemical polishing in an embodiment of the present invention;

[0062] Figure 14 This is a schematic diagram illustrating the change of the radial profile of the workpiece surface with the processing sequence in an embodiment of the present invention;

[0063] Figure 15 This is a schematic diagram showing the relationship between the predicted flatness and processing time during the first chemical mechanical polishing in an embodiment of the present invention (Φ100mm×3mm, r1=110mm, e=70mm, w1=30rpm, w2=39rpm);

[0064] Figure 16 This is a schematic diagram showing the predicted PV of 33.9 μm after the first chemical mechanical polishing process for 180 min in an embodiment of the present invention.

[0065] Figure 17 This is a schematic diagram showing the PV of 30.9 μm after the first chemical mechanical polishing process for 180 min in this embodiment of the invention.

[0066] Figure 18 This is a schematic diagram comparing the predicted and measured radial profiles of the workpiece surface during the first chemical mechanical grinding process in this embodiment of the invention.

[0067] Figure 19 This is a schematic diagram of the initial PV of 12.9 μm after the fourth chemical mechanical polishing in this embodiment of the invention;

[0068] Figure 20 This is a schematic diagram illustrating the relationship between predicted flatness and processing time in an embodiment of the present invention (Φ100mm×3mm, r1=110mm, e=70mm, w1=30rpm, w2=39rpm);

[0069] Figure 21 This is a schematic diagram showing the predicted PV of 8.3 μm after 60 minutes of the fourth chemical mechanical polishing process in an embodiment of the present invention.

[0070] Figure 22 This is a schematic diagram showing the PV of 8.5 μm after the fourth chemical mechanical polishing process for 60 minutes in this embodiment of the invention.

[0071] Figure 23 This is a schematic diagram comparing the predicted and measured radial profiles of the workpiece surface during the fourth chemical mechanical grinding process in this embodiment of the invention.

[0072] Figure 24 This is a schematic diagram of the initial PV of 4.2 μm after the 7th chemical mechanical polishing in this embodiment of the invention;

[0073] Figure 25 This is a schematic diagram showing the relationship between the predicted flatness and processing time during the 7th chemical mechanical polishing in this embodiment of the invention (Φ100mm×3mm, r1=110mm, e=70mm, w1=30rpm, w2=39rpm);

[0074] Figure 26 This is a schematic diagram of the predicted PV2.1μm after 30 minutes of chemical mechanical polishing in the 7th chemical mechanical polishing process in this embodiment of the invention;

[0075] Figure 27 This is a schematic diagram showing the PV2.0μm after the 7th chemical mechanical polishing process in this embodiment of the invention, after 30 minutes of actual processing.

[0076] Figure 28 This is a schematic diagram comparing the predicted and measured radial profiles of the workpiece surface during the 7th chemical mechanical grinding process in this embodiment of the invention.

[0077] Figure 29 This is a schematic diagram of the front profile PV = 2.0 μm before low-pressure electrochemical mechanical polishing in an embodiment of the present invention;

[0078] Figure 30 The roughness R before low-pressure electrochemical mechanical polishing in this embodiment of the invention is... a Schematic diagram of 339.4nm;

[0079] Figure 31 This is a schematic diagram showing the surface area PV = 2.4 μm after 1 hour of low-pressure electrochemical mechanical polishing in an embodiment of the present invention.

[0080] Figure 32 The surface roughness R after 1 hour of low-pressure electrochemical mechanical polishing in this embodiment of the invention is... a Schematic diagram of 177.8nm;

[0081] Figure 33 This is a schematic diagram showing the shape PV = 2.0 μm after 2 hours of low-pressure electrochemical mechanical polishing in an embodiment of the present invention;

[0082] Figure 34 The surface roughness R after 2 hours of low-pressure electrochemical mechanical polishing in this embodiment of the invention is... a Schematic diagram of 4.2nm. Detailed Implementation

[0083] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0084] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0085] In view of the processing requirements of large-diameter thin metal plates in physical experiments and the problems existing in the existing processing technologies, the present invention proposes a processing technology for large-diameter thin metal plates with high surface shape accuracy and high surface quality. First, a high-potential and low-pressure electrochemical grinding method is adopted to achieve efficient and low-stress thinning of the thin metal plate; then, a chemical mechanical grinding method based on pressure and speed regulation is adopted to effectively reduce the surface shape error of the pure copper thin plate; finally, a low-pressure electrochemical mechanical polishing method is adopted to obtain a thin metal plate with high surface quality while ensuring the surface shape accuracy.

[0086] For the convenience of understanding, the electrochemical grinding method, the chemical mechanical grinding method and the electrochemical mechanical polishing method will be described in detail below.

[0087] (1) The high-potential and low-pressure electrochemical grinding method uses a hydroxyethylidene diphosphonic acid (HEDP)-based electrolyte at the limiting current plateau potential above the passivation region to generate an inhibition film to replace the passivation film to protect the metal processing surface at a potential above the passivation region, and couples with the frictional action of the abrasive grains of the diamond abrasive pad. At a low grinding pressure (P = 0.27 psi), the surface roughness of the processing surface can be rapidly reduced, and the surface residual stress can be reduced; in addition, the edge of the workpiece is at a high electric potential affected by the tip effect of the sharp part, and the removal rate is higher than that of other parts. Coupled with the negative correlation between the interelectrode distance between the workpiece and the counter electrode and the material removal rate, the irregular surface shape of the workpiece can be transformed into a centrosymmetric surface shape.

[0088] The composition of the HEDP-based electrolyte is: 5-10 wt% of HEDP, 0.1-0.5 wt% of methylbenzotriazole, 1-5 wt% of ammonium citrate, 3-6 wt% of potassium hydroxide and deionized water; the pH of the HEDP-based electrolyte is 8-9.

[0089] (2) The chemical mechanical grinding method based on pressure and speed regulation is used for controlling the surface shape error of large-diameter thin plate parts. The specific steps are as follows: First, according to the initial surface shape of the workpiece, a processing method is selected; for a centrosymmetric convex surface shape or concave surface shape, directly enter the next step; for a non-centrosymmetric surface shape, first select the chemical mechanical grinding motion parameters according to the overall concave-convex situation of the surface shape. For a workpiece with an overall convex surface shape, chemical mechanical grinding is carried out with an eccentricity e > r1 - r2 to transform it into a centrosymmetric concave surface shape; for a workpiece with an overall concave surface shape, chemical mechanical grinding is carried out with an eccentricity e < r2 to transform it into a centrosymmetric concave surface shape; then, for the surface shape of the workpiece after processing, that is, a centrosymmetric convex surface shape or a centrosymmetric concave surface shape, a surface shape prediction model of a large-diameter thin plate considering the influence of pressure and speed distribution on the material removal amount is established, the chemical mechanical grinding motion parameters are selected, the relationship between the predicted surface shape error of the workpiece and the processing time is determined, a suitable processing time is selected, the surface shape of the workpiece after processing is predicted, and processing is carried out according to the predetermined processing parameters, so as to reduce the surface shape error of the workpiece.

[0090] Among them, the eccentricity is e, the radius of the polishing pad is r1, and the radius of the workpiece is r2; when facing the convex surface shape, adjust the eccentricity to the range of e>r1 - r2 for chemical mechanical polishing; under this condition, the edge of the workpiece is exposed on the polishing pad to increase the pressure between the central area of the workpiece and the grinding tool and the relative speed of the central area of the workpiece with respect to the polishing pad, reduce the contact time between the edge of the workpiece and the grinding tool, thereby increasing the material removal amount in the central area of the workpiece and quickly reducing the surface shape error; when facing the concave surface shape, adjust the eccentricity to the range of e<r2 for chemical mechanical polishing. When the eccentricity e is lower than the radius r2 of the workpiece and approaches zero, the relative speed of the edge of the pure copper thin plate is higher than that at the center, so that the material removal amount at the edge is higher than that at the center. The radial distribution of the material removal amount in the entire area of the workpiece is characterized in that its distribution is approximately parabolic, low in the center and high at the edge, so as to reduce the surface shape error of the workpiece.

[0091] The motion parameters include eccentricity, the rotation speed of the workpiece, and the revolution speed of the polishing pad.

[0092] The predicted surface shape is obtained by subtracting the material removal amount in the entire area from the initial surface shape of the workpiece. The material removal amount at any point on the processed surface is calculated based on the Preston equation, which is obtained by multiplying the MRR by the processing time T. And MRR is the product of the Preston coefficient k, the pressure P between the workpiece and the grinding tool, and the absolute value V of the relative speed; next, the distribution of the material removal amount in the entire area is obtained by multiplying the pressure distribution in the entire area between the workpiece and the grinding tool, the distribution of the absolute value V of the relative speed, the Preston coefficient k, and the processing time T.

[0093] When the eccentricity e>r1 - r2, the pressure distribution between the workpiece and the grinding tool is characterized in that it shows a linear distribution along the out-edge direction of the workpiece in the entire area, and the slope of the pressure distribution function increases with the increase of the out-edge distance.

[0094] The polishing pad is a fixed abrasive pad, and the polishing liquid is an acidic polishing liquid based on persulfate as the basic component. <0000​​​​​​​​​​The main parameters are as follows: O1C = r1, the radius of the polishing pad; O2D = r2, the radius of the workpiece; O2B = y, the ordinate of the out-edge range on the workpiece; CD = l, the out-edge distance; AD = s, the full length of the beam; f(x), the pressure distribution between the AC section of the workpiece and the polishing pad; a, b, the corresponding coefficients of the pressure distribution function; O1O2 = e, the eccentricity; w1, the rotational speed of the polishing pad; w2, the rotational speed of the workpiece.

[0098] Assume that the intersection of any beam AD along the x1 direction on the workpiece and the edge is C. Then the relationship between the out-edge distance l, the eccentricity e, the radius r1 of the polishing pad, and the radius r2 of the workpiece is:

[0099]

[0100] The relationship between the full length s of the beam, the radius r2 of the workpiece, and the ordinate y where the beam is located is:

[0101]

[0102] According to the previous inference, when the centroids of all the protruding beams in the workpiece do not exceed the support edge, there is no shear force and bending moment between the protruding beams that do not expose the edge and the protruding beams that expose the edge. That is, when the diameter along O2B on the workpiece does not expose the polishing pad, there is no shear force and bending moment between any two beams along the x1 direction on the workpiece. If the diameter along O2B is entirely on the polishing pad, then the intersection point (e, r2) of the workpiece and the diameter along O2B must be on the polishing pad, and the eccentricity e, the radius r1 of the polishing pad, and the radius r2 of the workpiece must satisfy:

[0103]

[0104] Let m be the mass of the workpiece and g be the acceleration due to gravity. If the eccentricity e, the radius r1 of the polishing pad, and the radius r2 of the workpiece satisfy the condition of Equation (3), and the pressure distribution function f(x) is calculated based on the linear model as the basic model, we get [[ID=2,3]]

[0105]

[0106] Through Equation (4), the pressure distribution over the entire area between the workpiece and the grinding tool can be obtained when the eccentricity e > r1 - r2. When the eccentricity e < r2, the pressure distribution over the entire area between the workpiece and the grinding tool obtained through Equation (4) is a uniform distribution. Since the workpiece is completely on the polishing pad at this time, it conforms to the assumption of an approximately uniform distribution.

[0107] Subsequently, the absolute value distribution of the relative velocity between the workpiece and the polishing pad is calculated. Taking Figure 4 point C in it as an example, assume the coordinates of point C are (x, y). Assume the velocity V1 at the point on the polishing pad that coincides with point C and the velocity V2 at point C on the workpiece. Then the velocity component of V1 decomposed along the x1 axis is:

[0108] V1x = -w1·y (5)

[0109] The velocity of V1 decomposed along the y1 axis is:

[0110] V 1y = w1·x (6)

[0111] Similarly, the velocity of V2 decomposed along the x1 axis is:

[0112] V 2x = -w2·y (7)

[0113] The velocity of V2 decomposed along the y1 axis is:

[0114] V 2y = w2·(x - e) (8)

[0115] Combining equations (5) to (8), the absolute value of the relative velocity at point C can be obtained as:

[0116]

[0117] That is:

[0118]

[0119] By analogy, the absolute value of the relative velocity at any point in the contact area between the workpiece and the polishing pad can be obtained through equation (10). The absolute value of the relative velocity conforms to equation (10) both when the eccentricity e > r1 - r2 and e < r2. Then, the instantaneous material removal rate is calculated. However, the Preston coefficient k has not been calibrated yet. We can first set k as a constant value for calculation to check whether the distribution trend of the material removal rate of the workpiece material conforms to the expectation. Later, combined with the actual surface shape results in the calibration experiment, after obtaining the distribution of the instantaneous material removal rate of the workpiece through calculation, the distribution result of the material removal rate within the rotation period of the workpiece can be obtained according to the rotation speed of the workpiece. Then, subtracting the material removal rate of the entire area from the initial surface shape of the workpiece can obtain the predicted surface shape, and further, the relationship between the predicted surface shape error of the workpiece and the processing time can be obtained. Finally, the surface shape error of the workpiece is controlled.

[0120] The calculation process of the surface shape prediction model is as Figure 5 shown. First, the initial surface shape of the workpiece is imported into the surface shape prediction model. Then, according to the initial surface shape of the workpiece, the motion parameters are selected to adjust the distribution of the material removal rate on the copper plate surface specifically. Next, the relationship between the flatness of the workpiece and the processing time is calculated. Furthermore, the processing time is selected according to the relationship between the flatness of the workpiece and the processing time. Finally, the predicted surface shape of the workpiece under the selected processing parameters is obtained.

[0121] The surface shape error control is based on the surface shape prediction model, and its processing process is as Figure 6As shown, firstly, the surface shape of the workpiece to be processed is measured and imported into the surface shape prediction model. Then, the processing parameters are selected (selecting motion parameters, calculating the relationship between flatness and processing time, and selecting an effective time to reduce flatness before the flatness drops to the lowest point, combined with the actual working conditions). Then, after the predicted flatness decreases, the workpiece is processed according to the parameters selected in the surface shape prediction model. If the measured flatness of the workpiece decreases, the purpose of surface shape error control is achieved.

[0122] (3) Electrochemical mechanical polishing method: The electrolyte is selected according to the initial surface roughness. For roughness R... a For surfaces with a roughness greater than 350nm, electrochemical mechanical polishing of thin sheet parts was first performed using a thiosalicylic acid-based electrolyte at a working pressure (P≤0.3psi). Processing parameters were selected using the coefficient of variation method to reduce the workpiece roughness to R0.3. a ≤30nm, then electrochemical mechanical polishing of the thin plate parts was performed using a glycine-phenyltriazole electrolyte at low polishing pressure (P≤0.3psi). The processing parameters were selected using the coefficient of variation method to reduce the roughness to R. a ≤5nm. For roughness R a For surfaces with a diameter of ≤350nm, polishing is performed directly using a glycine-phenyltriazole electrolyte.

[0123] The thiosalicylic acid-based electrolyte consists of 1–10 wt% glycine, 1.1–1.5 wt% thiosalicylic acid, 1–5 wt% polyethylene glycol, 1–9 wt% silica sol, 1–5 wt% potassium hydroxide (KOH), and deionized water, with a pH of 8.5.

[0124] The glycine-phenyltriazole electrolyte consists of 3.5–4 wt% glycine, 1–1.5 wt% phenyltriazole, 2–2.5 wt% KOH, 2–3 wt% silica sol with a particle size of 50 nm, and deionized water, with a pH of 8.5.

[0125] The following detailed explanation uses a specific example of machining large-diameter thin-plate pure copper parts to illustrate the high surface accuracy and high surface quality machining method for the aforementioned large-diameter thin-plate metal parts. For example... Figure 7 As shown, the processing method includes three stages: electrochemical grinding (thinning and surface shape transformation), surface shape error control, and electrochemical mechanical polishing (surface quality improvement).

[0126] During the electrochemical polishing stage, a pure copper sheet (Φ100mm×3mm) was processed for 10 minutes using high-potential, low-voltage electrochemical polishing parameters. The surface roughness was then measured using a Taylor profilometer. The surface roughness before and after processing is as follows: Figure 8 , Figure 9 As shown. After electrochemical polishing, the surface roughness of the copper sheet decreased from R... a607.0nm down to R a 162.4nm, a decrease of 73.2%.

[0127] Next, to test the ability of the high-potential, low-voltage electrochemical polishing method to maintain the flatness of the pure copper sheet, a pure copper sheet with a diameter of 100mm and a diameter of 3mm was processed. The process was repeated 5 times, with each processing session lasting 30 minutes. After processing, the surface shape of the pure copper sheet was inspected by a flatness meter, and its surface shape and flatness value were recorded.

[0128] The results showed that after five rounds of high-potential, low-voltage, high-intensity electrochemical polishing, the flatness of the pure copper sheet remained at approximately PV49.0 μm, with no further increase. Figure 10 As shown. After processing, the surface shape of the pure copper sheet still maintains a centrally symmetrical convex shape, such as... Figures 11-13 As shown, this is beneficial for reducing surface shape errors in the next stage through a chemical mechanical polishing method based on pressure and speed control. The MRR, calculated by the gravimetric method, is approximately 1 μm / min, which is in line with expectations. In summary, high-potential, low-pressure electrochemical polishing can achieve an MRR of approximately 1 μm / min at 0.27 psi, enabling the surface roughness of the processed pure copper sheet to reach approximately R0. a 150nm and avoid a significant increase in surface shape error.

[0129] Next, surface shape error control was performed on a pure copper sheet (Φ100mm×3mm). The processing parameters and surface shape error results used in the surface shape error control process are shown in Table 1. The change process of the radial contour of the workpiece surface with the processing sequence is as follows: Figure 14 As shown in the figure. The results show that the surface shape error of the workpiece is effectively reduced with the processing sequence, and the radial profile of the workpiece surface tends to be flat.

[0130] Table 1

[0131]

[0132] In the first processing, according to Figure 13 As shown, after thinning, the pure copper sheet exhibits a centrally symmetrical convex surface (PV = 48.5 μm). Since there are no obvious stepped convexities, the edge distance should not exceed 20% of the workpiece radius. Therefore, an eccentricity e = 70 mm, a revolution speed w1 = 30 rpm, and a rotation speed w2 = 39 rpm are selected and imported into the surface shape prediction model (grinding pad radius r1 = 110 mm). Through calculation, the relationship between the predicted flatness (PV) and processing time is obtained, as follows: Figure 15As shown, the flatness decreases linearly with processing time. However, hydrophilic diamond bonded abrasive pads require regular cleaning and maintenance, so the processing time should not be too long; a processing time of t = 180 min is initially selected. According to predictions, after 180 min of processing, the flatness of the pure copper sheet decreases from PV48.5 μm to PV33.9 μm, and the workpiece surface shape remains a centrally symmetrical convex shape, as shown... Figure 16 As shown.

[0133] A pure copper sheet was chemically and mechanically ground at e = 70 mm, w1 = 30 rpm, w2 = 39 rpm, and T = 180 min. After processing, the workpiece surface shape was measured using a flatness meter, and the measured flatness of the workpiece was PV 30.9 μm. Figure 17 As shown, the flatness prediction error rate is less than 10%. The predicted and measured radial profiles of the surface are basically similar, as shown below. Figure 18 As shown.

[0134] In the fourth machining operation, the initial surface shape of the workpiece was PV12.9μm, as shown below. Figure 19 As shown. Since the initial surface shape of the workpiece is a centrally symmetrical convex shape without obvious steps, the motion parameters from the first iteration are used (eccentricity e = 70 mm, revolution speed w1 = 30 rpm, rotation speed w2 = 39 rpm). The motion parameters are imported into the surface shape prediction model, and the relationship between the predicted flatness and processing time is obtained through calculation, as shown below. Figure 20 As shown, the flatness initially decreases with processing time, but a lag occurs after 100 minutes, and then increases with processing time after 140 minutes. Since the flatness of the pure copper sheet is predicted to increase after 120 minutes of processing, the processing time should satisfy T ≤ 120 minutes. A processing time of t = 60 minutes is selected. According to the prediction, after 60 minutes of processing, the predicted flatness of the pure copper sheet decreases from PV12.9 μm to PV8.3 μm, still maintaining a centrally symmetrical convex surface shape, as shown... Figure 21 As shown.

[0135] After machining a pure copper sheet at e=70mm, w1=30rpm, w2=39rpm, and T=60min, the workpiece was measured using a FlatMaster200 flatness tester. The measured flatness of the workpiece was PV8.5μm. Figure 22 As shown, the flatness prediction error rate is less than 10%. The predicted and measured radial profiles of the surface match well, as shown in the figure. Figure 23 As shown.

[0136] In the 7th processing, such as Figure 24As shown. Although the initial flatness of the workpiece is lower than PV5μm, a significant step appears within Φ80mm. An eccentricity of e = 70mm should be used to concentrate the material removal within the Φ80mm area. The parameter combination of revolution speed w1 = 30rpm and rotation speed w2 = 39rpm is imported into the surface shape prediction model. Through calculation, the relationship between predicted flatness (PV) and processing time is obtained, as shown below. Figure 25 As shown, the flatness initially decreases with processing time, then increases after 30 minutes. Therefore, a processing time of t = 30 minutes is chosen. According to predictions, after 30 minutes of processing, the flatness of the pure copper sheet decreases from PV4.2μm to PV2.1μm, but it still maintains a centrally symmetrical convex surface shape, as shown... Figure 26 As shown.

[0137] A pure copper sheet was chemically and mechanically ground at e = 70 mm, w1 = 30 rpm, w2 = 39 rpm, and T = 30 min. After processing, the workpiece surface shape was measured using a flatness meter, and the measured flatness of the workpiece was PV 2.0 μm. Figure 27 As shown. The flatness prediction error rate is less than 10%. The predicted radial profile of the surface basically matches the measured radial profile of the surface. In summary, after seven cycles of chemical mechanical polishing based on pressure and speed control, the flatness of the pure copper sheet decreased from PV48.5μm to PV2.0μm, with a flatness prediction error rate of less than 10%, and the predicted radial profile of the surface basically matches the measured radial profile of the surface, effectively reducing the surface shape error of the pure copper sheet, as shown. Figure 28 As shown.

[0138] After controlling for surface shape errors, this invention uses B2 electrolyte to perform low-pressure electrochemical mechanical polishing on pure copper sheets. The processing parameters are: polishing pressure P = 0.27 psi, polishing pad revolution speed w1 = 40 rpm, workpiece rotation speed w2 = 45 rpm, and electrolyte flow rate 25 ml / min. The flatness and roughness of the pure copper sheet before polishing are as follows: Figure 29 , Figure 30 As shown, the flatness is PV2.0μm and the roughness is R. a The surface roughness was 339.4 nm, with a roughness measurement range of 0.36 mm × 0.27 mm. This relatively high roughness was attributed to the strong oxidizing effect of persulfate in the polishing slurry, which degraded the surface quality. To improve surface quality, electrochemical mechanical polishing of the pure copper sheet for 1 hour resulted in an increase in flatness to PV 2.4 μm and a decrease in roughness to R. a 177.8nm, a significant improvement compared to before polishing, with a marked reduction in the number of surface scratches, such as... Figure 31 , Figure 32 As shown in the figure. This result preliminarily demonstrates the surface quality improvement effect of B2 electrolyte on pure copper sheets under low polishing pressure.

[0139] After electro-chemical mechanical polishing for 1 h, the flatness of the pure copper thin sheet is reduced to PV 2 μm; the roughness is reduced to R a 4.2 nm, showing obvious improvement compared with that before polishing. The surface is uniform, as shown in Figure 33 、 Figure 34 . To sum up, according to the high surface shape accuracy and high quality processing scheme for the large-diameter pure copper thin sheet, the pure copper thin sheet (Φ100 mm × 3 mm) is processed. After thinning, surface shape error control and surface quality improvement, the flatness of the pure copper thin sheet finally reaches PV ≤ 2 μm, and the roughness R a ≤ 5 nm.

[0140] In the processing method in the above embodiment, the thin sheet is electro-chemically ground to achieve efficient low-stress thinning, and then chemical mechanical polishing with surface shape prediction ability is used to reduce the surface shape error of the thin sheet. Finally, electro-chemical mechanical polishing is used to achieve high surface quality processing of the thin sheet. At the limiting current plateau potential higher than the passivation region potential, electro-chemical grinding can thin the workpiece at a higher material removal rate, reduce the roughness, improve the processing efficiency, and make the irregular surface shape of the workpiece transform into a centrosymmetric surface shape by virtue of the tip effect at the edge of the workpiece and the negative correlation between the pole pitch and the material removal rate. During the surface shape error control process, only the initial surface shape data of the workpiece needs to be provided to the surface shape prediction model, and the predicted surface shape of the workpiece corresponding to the selected processing parameters can be obtained within 5 min after input. After inputting the initial surface shape data of the workpiece, the relationship between the surface shape error of the workpiece and the processing time can be obtained within 5 min, and the optimal processing time corresponding to the lowest surface shape error can be obtained, avoiding overprocessing and saving resources. In addition, only a general single-side grinding and polishing machine is required, and the working disk diameter d1 and the thin sheet diameter d2 satisfy d2 < d1 ≤ 2d2, enabling the large-diameter thin sheet parts to obtain micron-level surface shape accuracy and reducing the equipment cost. In the electro-chemical mechanical polishing process, a significant improvement in the processing surface quality is achieved on the basis of no obvious deterioration of the surface shape accuracy. The present invention overcomes the problem that the large-diameter metal thin sheet is sensitive to force and thermal loads, and realizes the high surface shape accuracy and high surface quality processing of the large-diameter metal thin sheet.

[0141] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for machining large-diameter thin metal plate parts, characterized in that, The method includes: Electrochemical grinding of the metal plate to be processed is carried out according to the high potential low voltage electrochemical grinding processing parameters to obtain a large diameter thin metal plate workpiece after thinning and surface shape transformation. The surface shape error of the workpiece is controlled by a chemical mechanical polishing method based on pressure and speed regulation, and the distribution of surface material removal is adjusted accordingly. Low-pressure electrochemical mechanical polishing of large-diameter thin metal plates after surface shape error control includes: Select the electrolyte based on the initial surface roughness; for roughness... R a The >350nm processing surface is first processed using a thiosalicylic acid-based electrolyte at a working pressure. P Electrochemical mechanical polishing of thin sheet metal parts was performed at ≤0.3 psi, and the machining parameters were selected using the coefficient of variation method to reduce the workpiece roughness to a minimum. R a ≤30nm, then glycine-phenyltriazole electrolyte was used at low polishing pressure P Electrochemical mechanical polishing of thin sheet metal parts was performed at ≤0.3 psi, and the machining parameters were selected using the coefficient of variation method to reduce the surface roughness to a minimum. R a ≤5nm; for roughness R a Surfaces with a diameter of ≤350nm are directly polished using a glycine-phenyltriazole electrolyte. The components of the thiosalicylic acid-based electrolyte include: 1~10wt% glycine, 1.1~1.5wt% thiosalicylic acid, 1~5wt% polyethylene glycol, 1~9wt% silica sol, 1~5wt% potassium hydroxide and deionized water, and the pH of the thiosalicylic acid-based electrolyte is 8.

5. The glycine-phenyltriazole electrolyte comprises: 3.5-4 wt% glycine, 1-1.5 wt% phenyltriazole, 2-2.5 wt% potassium hydroxide, 2-3 wt% silica sol with a particle size of 50 nm and deionized water, and the pH of the glycine-phenyltriazole electrolyte is 8.

5.

2. The method for processing large-diameter thin metal plate parts according to claim 1, characterized in that, Electrochemical grinding of the metal plate to be processed is performed according to high-potential, low-voltage, high-strength electrochemical grinding parameters, including: A hydroxyethylidene diphosphonic acid-based electrolyte is used to generate a corrosion-inhibiting film to replace the passivation film and protect the metal surface at a limiting current level higher than the passivation zone. This film is coupled with the abrasive friction of a diamond-bonded abrasive pad to perform electrochemical polishing under low polishing pressure.

3. The method for processing large-diameter thin metal plate parts according to claim 2, characterized in that, The hydroxyethylidene diphosphonic acid-based electrolyte comprises: 5-10 wt% hydroxyethylidene diphosphonic acid, 0.1-0.5 wt% methylbenzotriazole, 1-5 wt% ammonium citrate, 3-6 wt% potassium hydroxide, and deionized water; the pH of the hydroxyethylidene diphosphonic acid-based electrolyte is 8-9.

4. The method for machining large-diameter thin metal plate parts according to claim 1, characterized in that, A chemical mechanical polishing method based on pressure and speed control is used to control the surface shape error of the workpiece, including: The initial surface shape of the workpiece is processed to obtain a centrally symmetrical convex surface shape or a centrally symmetrical concave surface shape; To predict the surface shape of a large-diameter thin plate after workpiece processing, a model is established that considers the influence of pressure and velocity distribution on the amount of material removed. Determine the motion parameters for chemical mechanical polishing, including: eccentricity, workpiece rotation speed, and polishing pad revolution speed; when facing a raised surface, adjust the eccentricity to... e > r 1- r 2. Perform chemical mechanical grinding within the specified range; when facing concave surfaces, adjust the eccentricity to... e < r 2. Perform chemical mechanical grinding within the specified range, when e Below the workpiece radius r 2. As the velocity approaches zero, the relative velocity at the edge of the metal sheet is higher than that at the center, resulting in a higher material removal rate at the edge compared to the center; where, e Indicates eccentricity. r 1 indicates the radius of the grinding pad. r 2 indicates the workpiece radius; Based on the surface shape prediction model and the motion parameters, the relationship between the predicted surface shape error and the processing time is obtained. Based on the relationship between the predicted surface shape error and the processing time, the processing time of the workpiece is determined. The workpiece is processed according to the processing time and the motion parameters.

5. The method for processing large-diameter thin metal plate parts according to claim 4, characterized in that, Processing the initial surface shape of the workpiece to obtain a centrally symmetric convex surface shape or a centrally symmetric concave surface shape includes: If the initial surface shape of the workpiece is a centrally symmetrical convex or concave surface shape, no processing is required; If the initial surface shape of the workpiece is non-centrosymmetric, the chemical mechanical grinding motion parameters are selected based on the overall concavity and convexity of the surface. For workpieces with an overall convex surface, the following parameters are used: e > r 1- r 2. Perform chemical mechanical grinding to transform it into a centrally symmetric concave surface; for workpieces with an overall concave surface, use... e < r 2. Perform chemical mechanical grinding to transform it into a centrally symmetrical concave surface.

6. The method for machining large-diameter thin metal plate parts according to claim 1, characterized in that, A prediction model for the surface shape of large-diameter thin plates, considering the influence of pressure and velocity distribution on material removal, is established, including: By material removal rate and processing time T The product yields the amount of material removed at any point on the machined surface, where the material removal rate is the Preston coefficient. k Pressure between the workpiece and the mold P relative velocity absolute value V The product; By analyzing the pressure distribution and absolute value of relative velocity across the entire area between the workpiece and the grinding wheel V Distribution, Preston coefficient k With processing time T The product yields the distribution of material removal across the entire area; Calculate the pressure distribution over the entire area between the workpiece and the grinding wheel; Calculate the absolute value of the relative velocity at any point in the contact area between the workpiece and the grinding pad to obtain the distribution of the absolute value of the relative velocity over the entire area between the workpiece and the grinding wheel. Assuming Preston coefficient k Assuming a constant value, the instantaneous material removal distribution is obtained. Then, combined with the actual surface shape results from the calibration experiment, the Preston coefficient is calibrated using a one-dimensional search and trial-and-error method. k ; Through Preston coefficient k After multiplying the pressure distribution across the entire area between the workpiece and the grinding wheel and the absolute value distribution of the relative velocity across the entire area between the workpiece and the grinding wheel to obtain the instantaneous material removal distribution of the workpiece, the material removal amount across the entire area within the workpiece's rotation cycle is obtained based on the workpiece's rotation speed. The predicted surface shape of the workpiece is obtained by subtracting the total material removal amount from the initial surface shape of the workpiece.

7. The method for processing large-diameter thin metal plate parts according to claim 4, characterized in that: exist e>r 1- r 2. The pressure distribution between the workpiece and the grinding wheel is characterized by a linear distribution along the workpiece's edge direction throughout the entire region, and the slope of the pressure distribution function increases with the increase of the edge distance.

8. The method for machining large-diameter thin metal plate parts according to claim 4, characterized in that: The grinding pad is a bonded abrasive pad, and the grinding fluid is an acidic grinding fluid based on persulfate.

9. A method for machining large-diameter thin metal sheet parts according to any one of claims 1 to 8, characterized in that: The diameter of the large-diameter thin plate part is Φ50~Φ220mm, the thickness is 1.5~4mm, and the diameter-to-thickness ratio is ≥20.

Images