Method for determining microstructure parameters of workpiece surface and machining method thereof

Abstract

The application discloses a workpiece surface microstructure parameter determination method and a machining method thereof, and comprises the following steps: establishing a jagged chip geometric representation model, determining the jagged chip geometric parameters, and designing the microstructure parameters, based on the relationship between the established jagged chip geometric representation and the cutting parameters and the tool parameters, designing the microstructure array on the metal surface to be machined, the width W of the microstructure being equal to the jagged chip pitch P, and the depth D of the microstructure being equal to the difference H-h between the jagged chip wave crest height and the wave trough height, and further optimizing the microstructure design and machining, so that the problem that the cutting force fluctuation is caused by the jagged chip in the titanium alloy machining process, the tool wear is serious, and the machining precision is reduced is solved.

Description

Technical Field

[0001] This invention relates to the field of metal surface cutting technology, and in particular to a method for determining the microstructure parameters of a workpiece surface and a processing method thereof. Background Technology

[0002] For those with σ b Difficult-to-machine materials, such as titanium alloys, possess properties like high strength, good corrosion resistance, and high heat resistance, and are widely used in aerospace, medical devices, and deep-sea exploration due to their high performance. With the continuous development of aerospace and medical device industries, the demand for machining precision and quantity of aerospace components and medical equipment is increasing, leading to a growing need for ultra-precision machining. However, due to the low thermal conductivity, low elastic modulus, and high chemical reactivity of difficult-to-machine materials (such as titanium alloys), the machining process results in very high tool temperatures, severe wear, very short tool life, and insufficient machining precision.

[0003] To address this, researchers have developed numerous methods to reduce tool wear and improve machining accuracy. Among these, the methods closest to this invention include:

[0004] Method 1: Patent: Wang Sujuan, Lu Zhenhong, Sun Zhanwen, Xie Haizhen, Tang Wenyan, An Ultra-Precision Cutting Method Based on Surface Microstructure Design, ZL202110392431.7. This is an optimized system and method for diamond machining of difficult-to-machine materials based on the microstructure design of the workpiece surface. It obtains the designed micro / nano structures on the workpiece surface through semi-finishing processes, such as... Figure 1 As shown, a diamond tool is finally used to finish the microstructured surface. Its main disadvantages are: 1) The surface microstructure is not perpendicular to the cutting speed direction (most of the time the cutting speed direction forms an acute angle with the microstructure). Experiments have shown that the machining effect is best when the microstructure is perpendicular to the cutting speed direction. 2) The geometric characteristics of serrated chips are not considered; the designed surface microstructure cannot effectively suppress the generation of serrated chips. 3) The entire machining process is completed using a tool, resulting in high tool wear and consumption.

[0005] Method Two: This involves machining various microstructures, such as grooves and pits, onto the cutting tool. Currently, the main technologies for machining microstructures on cutting tool surfaces include micro-milling, laser processing, abrasive jet machining, and electrical discharge machining (EDM). The principle is to machine microstructures onto the cutting tool to trap debris, store lubricating oil to improve lubrication, and reduce the contact area between the tool and the workpiece. Its main disadvantages are: 1) Machining surface microstructures on cutting tools (such as diamond tools) is very difficult due to the high brittleness and hardness of diamond tools, leading to material particle shedding and frequent chipping of the cutting edge. 2) It requires additional processing equipment (such as laser processing equipment, EDM equipment, etc.), increasing processing costs. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the microstructure parameters of a workpiece surface and a processing method thereof, so as to solve the problems existing in the prior art, further optimize the microstructure design and processing, and solve the problem of cutting force fluctuation caused by the generation of serrated chips during the processing of titanium alloys, which leads to severe tool wear and reduced processing accuracy.

[0007] To achieve the above objectives, the present invention provides the following solution: The present invention provides a method for determining the microstructure parameters of a workpiece surface, comprising the following steps:

[0008] Establish a geometric characterization model for serrated chips: By analyzing the formation mechanism of serrated chips, establish the mapping relationship between the geometric parameters of serrated chips and the tool parameters and cutting parameters during the machining process. The geometric parameters of serrated chips include the pitch P, the difference between the peak height and the trough height Hh;

[0009] Determine the geometric parameters of the serrated chip: the cutting speed V of the tool. C The relationship between the spindle speed S and the spindle rotation speed S is as follows:

[0010] V c =2πSr ij (1),

[0011] Where, r ij For cutting point C ij (x ij ,y ij The distance from the center o of the workpiece surface to be cut, and At any point C on the surface of the workpiece to be machined ij (x ij ,y ij ), And determine the cutting speed V at that point based on the relationship. C The cutting speed V at that point CBy mapping the tool parameters and the geometric parameters of the serrated chip, the magnitude of the geometric parameters of the serrated chip under this cutting condition can be obtained;

[0012] Microstructure parameter design: Based on the established relationship between the geometric features of the serrated chip and the cutting parameters and tool parameters, the microstructure array is designed on the metal surface to be machined. The width W of the microstructure is equal to the pitch P of the serrated chip, and the depth D of the microstructure is equal to the difference Hh between the peak height and the trough height of the serrated chip.

[0013] Preferably, in the step of designing microstructure parameters, the microstructure is a strip-shaped groove structure, and is radially distributed with the center o of the surface to be cut as the center, and extends through the outer peripheral edge of the surface to be cut.

[0014] Preferably, the width W of the microstructure gradually increases from the center o of the cutting surface toward its outer periphery.

[0015] Preferably, the depth D of the microstructure gradually increases from the center o of the self-cutting surface towards its outer periphery.

[0016] A method for machining microstructures on the surface of a workpiece is also provided, comprising the following steps:

[0017] Analysis: Analyze the geometric features and precision requirements of the workpiece, and select the corresponding machining method;

[0018] Machining process planning: Based on the selected machining method, machining process planning is carried out, including determining tool parameters and setting the spindle speed S, feed rate f, and depth of cut Doc in the machining parameters;

[0019] Determine the microstructure parameters of the workpiece surface;

[0020] Preparation before processing: Determine the path planning and step size of the microstructure array on the grinding surface of the grinding wheel, and determine the geometry of the microstructure on the workpiece surface;

[0021] To complete the microstructure processing: After grinding a microstructure with a grinding wheel, rotate it by the corresponding angle and then process the next microstructure. The processing parameters are the same as those for processing the previous microstructure.

[0022] Preferably, the cutting direction of the tool is perpendicular to the extension direction of the microstructure.

[0023] Preferably, in the pre-machining preparation step, the workpiece surface has a circular structure, and the tool turning path is an Archimedean spiral, the equation of which in the rectangular coordinate system is:

[0024]

[0025] From this, we can obtain: x 2 +y 2=r 2 r is the turning trajectory radius, S is the spindle speed, and t is the cutting time.

[0026] Preferably, in the step of completing the microstructure machining, the central angle corresponding to a single microstructure is α, which is set as the rotation angle of the tool after machining the single microstructure, and

[0027] Preferably, before the pre-processing preparation step, the grinding wheel for the microstructure array grinding of the workpiece surface is designed, and the machining is performed using the arc contour portion of the grinding wheel, with the arc contour radius R of the grinding wheel being... w The calculation formula is:

[0028]

[0029] Where D is the depth of the microstructure and W is the width of the microstructure.

[0030] Preferably, the grinding wheel is a grinding tool made of non-metallic crystalline abrasive and a binder.

[0031] The present invention achieves the following technical effects compared to the prior art:

[0032] First, by setting the width W of the microstructure to be equal to the pitch P of the serrated chip, and the depth D of the microstructure to be equal to the value Hh, which is the difference between the peak height and the trough height of the serrated chip, the degree of serration of the serrated chip can be reduced to the greatest extent, thereby reducing tool wear and improving the machining accuracy of the workpiece.

[0033] Secondly, the microstructure is in the form of a strip-shaped groove and is radially distributed with the center o of the surface to be cut as the center. This completes the microstructure array on the workpiece, thereby avoiding the difficulties in machining and the adverse effects of tool chipping caused by machining microstructures on the tool.

[0034] Third, the cutting direction of the tool is perpendicular to the extension direction of the microstructure. At the same time, based on the geometric design of the serrated chip surface microstructure array structure, the microstructure array can better exert the inhibitory effect of the microstructure array on the serrated chip, minimize the serration degree of the serrated chip, improve machining accuracy and reduce tool wear.

[0035] Fourth, surface functional microstructure arrays can be machined on workpieces by using grinding wheels instead of tool scraping, which simplifies the machining of surface functional microstructure arrays, reduces tool wear, and improves the accuracy and economy of ultra-precision machining. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the processing in the existing technical method one;

[0038] Figure 2 This is a flowchart of the workpiece processing of the present invention;

[0039] Figure 3 This is the geometric representation model of the serrated chip of the present invention;

[0040] Figure 4 This is a graph showing the influence of the processing parameters of this invention on the geometry of serrated chips. Figure 4 -a is a graph showing the influence of cutting speed on the geometry of serrated chips. Figure 4 -b Cutting depth influences the geometry of serrated chips. Figure 4 -c tool rake angle influences the geometry of serrated chips; trend diagram.

[0041] Figure 5 This is a planar coordinate diagram of the microstructure fabrication of the present invention;

[0042] Figure 6 This is a schematic diagram of the microstructure fabrication process of the present invention;

[0043] Figure 7 This is a schematic diagram of the grinding wheel structure of the present invention;

[0044] Figure 8 A schematic diagram of microstructure path planning and step length structure for grinding wheel;

[0045] Among them, 1-microstructure, 2-grinding wheel. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0047] The purpose of this invention is to provide a method for determining the microstructure parameters of a workpiece surface and a processing method thereof, so as to solve the problems existing in the prior art, further optimize the microstructure design and processing, and solve the problem of cutting force fluctuation caused by the generation of serrated chips during the processing of titanium alloys, which leads to severe tool wear and reduced processing accuracy.

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] like Figures 1 to 8 As shown, this embodiment provides a method for determining the microstructure parameters of a workpiece surface, mainly targeting workpieces with σ b For difficult-to-machine materials with properties such as >1000MPa and δ>30%, such as titanium alloys, the following steps are included:

[0050] Establish a geometric representation model for serrated chips: such as Figure 3 As shown, the geometric representation model of serrated chips is given, where H is the peak height, h is the trough height, P is the pitch, θ is the serrated chip angle, and ψ is the shear angle. Figure 4 As shown, a mapping relationship is established between the geometric parameters (P, Hh) of serrated chips and the tool parameters and cutting parameters during machining. The geometric parameters of the serrated chips include the pitch P, the difference between the peak height and the trough height Hh. The influence of machining parameters on the geometry of serrated chips can be clearly obtained, specifically divided into... Figure 4 -a cutting speed, Figure 4 -b depth of cut Figure 4 -c Tool rake angle, and the geometric parameters (P, Hh) of the serrated chip are obtained. The serrated chip increases with the increase of cutting speed and depth of cut, and decreases with the increase of tool rake angle.

[0051] Determine the geometric parameters of the serrated chip: the cutting speed V of the tool. C The relationship between the spindle speed S and the spindle rotation speed S is as follows:

[0052] V c =2πSr ij (1),

[0053] Where, r ij For cutting point C ij (x ij ,y ij The distance from the center o of the workpiece surface to be cut, and At any point C on the surface of the workpiece to be cut ij (x ij ,y ij ), And determine the cutting speed V at that point based on the relationship. CThe cutting speed V at that point C By mapping the tool parameters and the geometric parameters of the serrated chip, the magnitude of the geometric parameters of the serrated chip under this cutting condition can be obtained;

[0054] Microstructure 1 structural parameter design: Based on the established relationship between the geometric features of the serrated chip and the cutting parameters and tool parameters, an array of microstructures 1 is designed on the metal surface to be machined. The width W of microstructure 1 is equal to the pitch P of the serrated chip, and the depth D of microstructure 1 is equal to the difference Hh between the peak height and trough height of the serrated chip. Among these, Figure 6 This is a planar diagram of the microstructure 1 array, where W is the width of microstructure 1, α is the central angle corresponding to a single microstructure 1, and C... ij Let r be any point on the cutting path. ij C is any point on the cutting path ij The distance to the center o of the workpiece. For example... Figure 7 This is an isometric view of the microstructure 1 array, where r p Let W be the workpiece radius and D be the depth of microstructure 1. The width W of microstructure 1 is equal to the serrated chip pitch P, and the depth D of microstructure 1 is equal to the difference between the peak height and trough height Hh of the serrated chip. This minimizes the serration of the serrated chip, reduces tool wear, and improves the machining accuracy of the workpiece.

[0055] In a preferred embodiment of the present invention, in the step of designing the structural parameters of microstructure 1, microstructure 1 is a strip-shaped groove structure, radially distributed with the center o of the cutting surface as the center, and extends through the outer peripheral edge of the cutting surface to form an array structure. This avoids the adverse effects of machining difficulties and tool chipping caused by machining microstructure 1 on the cutting tool. Preferably, the width W of microstructure 1 gradually increases from the center o of the cutting surface towards its outer periphery. Preferably, the depth D of microstructure 1 gradually increases from the center o of the cutting surface towards its outer periphery.

[0056] Furthermore, a method for processing microstructures 1 on the surface of a workpiece is also provided, mainly targeting workpieces with σ b For difficult-to-machine materials with properties such as >1000MPa and δ>30%, such as titanium alloys, the following steps are included:

[0057] Analysis: Analyze the geometric features and precision requirements of the workpiece, and select the corresponding machining method; if nanometer-level surface roughness is required, choose ultra-precision machining; if millimeter-level surface roughness is required, choose traditional machining methods; otherwise, precision machining methods can be used.

[0058] Machining process planning: Based on the selected machining method, machining process planning is carried out, including determining tool parameters and setting the spindle speed S, feed rate f, and depth of cut Doc in the machining parameters;

[0059] Determine the parameters of the workpiece surface microstructure;

[0060] Preparation before processing: Determine the array path planning and step size of the grinding wheel 2 grinding surface microstructure 1, and determine the geometry of the workpiece surface microstructure 1;

[0061] To complete the machining of microstructure 1: After grinding a microstructure 1 using grinding wheel 2, rotate it by the corresponding angle and then machine the next microstructure 1. The machining parameters are the same as those for machining the previous microstructure 1.

[0062] Furthermore, the cutting direction of the tool is perpendicular to the extension direction of the microstructure 1. At the same time, based on the geometric design of the serrated chip surface microstructure 1 array structure, the microstructure 1 array can better exert the inhibitory effect of the serrated chip, minimize the serration degree of the serrated chip, improve machining accuracy and reduce tool wear.

[0063] In a preferred embodiment of the present invention, during the pre-processing preparation step, the workpiece surface is circular, and the tool turning path is an Archimedean spiral, the equation of which in the Cartesian coordinate system is:

[0064]

[0065] From this, we can obtain: x 2 +y 2 =r 2 r is the turning trajectory radius, S is the spindle speed, and t is the cutting time.

[0066] Furthermore, in the step of completing the machining of microstructure 1, the central angle corresponding to a single microstructure 1 is α, which is set as the rotation angle of the tool after machining a single microstructure 1, and like Figure 8 As shown, α is the central angle corresponding to a single microstructure 1, which is set as the rotation angle of the spindle when machining the microstructure 1. W is the width of the microstructure 1, and D is the depth of the microstructure 1. After each microstructure 1 is machined by the grinding wheel 2, the spindle rotates by an angle α before machining the next microstructure 1, and the machining parameters are exactly the same as before.

[0067] Furthermore, prior to the machining preparation step, the design of the grinding wheel 2 for grinding the microstructure array 1 on the workpiece surface is performed. The grinding wheel 2 is used to replace tool scraping to machine the surface functional microstructure array 1 on the workpiece, simplifying the machining of the surface functional microstructure array 1, reducing tool wear, and improving ultra-precision machining accuracy and machining economy. Figure 8 The diagram shows the structure of grinding wheel 2, where φ is the bore diameter of grinding wheel 2, d1 is the inner diameter of the grinding wheel 2 base, d2 is the outer diameter of the grinding wheel 2 base, and R... wLet h1 be the radius of the arc of grinding wheel 2, h2 be the thickness of the base material, and h2 be the thickness of the arc of grinding wheel 2. Machining is performed using the arc contour of grinding wheel 2, with the arc contour radius R of grinding wheel 2 being... w The calculation formula is:

[0068]

[0069] Where D is the depth of microstructure 1 and W is the width of microstructure 1.

[0070] Preferably, the grinding wheel 2 is a grinding tool made of non-metallic crystalline abrasive and a bonding agent. During grinding, countless abrasive grains continuously grind the surface of the workpiece. The workpiece is essentially being ground, with the surface deformed under the pressure and friction of the numerous abrasive grains, which then becomes part of the grinding process. Grinding many cutting points tends to produce smaller chips, thereby improving surface finish. In ultra-precision grinding, diamond grinding wheels 2 can be used to machine the microstructure array 1 on the surface. Compared with cutting tools, grinding wheels 2 have less wear and a longer service life.

[0071] This invention improves existing microstructure 1 design and processing methods to address problems in titanium alloy machining, such as severe fluctuations in cutting force caused by serrated chips, the formation of periodic contours on the machined surface, which ultimately lead to severe tool wear and poor surface quality.

[0072] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0073] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0074] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for determining the microstructure parameters of a workpiece surface, characterized in that, Includes the following steps: Establish a geometric characterization model for serrated chips: By analyzing the formation mechanism of serrated chips, establish the mapping relationship between the geometric parameters of serrated chips and the tool parameters and cutting parameters during the machining process. The geometric parameters of serrated chips include the pitch P, the difference between the peak height and the trough height Hh; Determine the geometric parameters of the serrated chip: the cutting speed V of the tool. C The relationship between the spindle speed S and the spindle rotation speed S is as follows: V c =2πSr ij (1), Where, r ij For cutting point C ij (x ij ,y ij The distance from the center o of the workpiece surface to be cut, and At any point C on the surface of the workpiece to be cut ij (x ij ,y ij ), And determine the cutting speed V at that point based on the relationship. C The cutting speed V at that point C By mapping the tool parameters and the geometric parameters of the serrated chip, the magnitude of the geometric parameters of the serrated chip under this cutting condition can be obtained; Microstructure structural parameter design: Based on the established relationship between the geometric features of the serrated chip and the cutting parameters and tool parameters, the microstructure array is designed on the metal surface to be machined. The width W of the microstructure is equal to the pitch P of the serrated chip, and the depth D of the microstructure is equal to the difference Hh between the peak height and the trough height of the serrated chip.

2. The method for determining the microstructure parameters of a workpiece surface according to claim 1, characterized in that, In the step of designing microstructure parameters, the microstructure is a strip-shaped groove structure, and is radially distributed with the center o of the surface to be cut as the center, and extends through the outer peripheral edge of the surface to be cut.

3. The method for determining the microstructure parameters of a workpiece surface according to claim 2, characterized in that, The width W of the microstructure gradually increases from the center o of the cutting surface toward its outer periphery.

4. The method for determining the microstructure parameters of a workpiece surface according to claim 3, characterized in that, The depth D of the microstructure gradually increases from the center o of the self-cutting surface towards its outer periphery.

5. A method for machining microstructures on the surface of a workpiece using the method for determining microstructure parameters of the workpiece surface as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Analysis: Analyze the geometric features and precision requirements of the workpiece, and select the corresponding machining method; Machining process planning: Based on the selected machining method, machining process planning is carried out, including determining tool parameters and setting the spindle speed S, feed rate f, and depth of cut Doc in the machining parameters; Determine the microstructure parameters of the workpiece surface; Preparation before processing: Determine the path planning and step size of the microstructure array on the grinding surface of the grinding wheel, and determine the geometry of the microstructure on the workpiece surface; To complete the microstructure processing: After grinding a microstructure with a grinding wheel, rotate it by the corresponding angle and then process the next microstructure. The processing parameters are the same as those for processing the previous microstructure.

6. The method for processing microstructures on the surface of a workpiece according to claim 5, characterized in that, The cutting direction of the tool is perpendicular to the extension direction of the microstructure.

7. The method for processing microstructures on the surface of a workpiece according to claim 6, characterized in that, In the pre-machining preparation step, the workpiece surface has a circular structure, and the tool turning path is an Archimedean spiral, whose equation in the rectangular coordinate system is: From this, we can obtain: x 2 +y 2 =r 2 r is the turning trajectory radius, S is the spindle speed, and t is the cutting time.

8. The method for processing microstructures on the surface of a workpiece according to claim 7, characterized in that, In the process of machining microstructures, the central angle corresponding to a single microstructure is α, which is set as the rotation angle of the tool after machining the single microstructure.

9. The method for processing microstructures on the surface of a workpiece according to claim 8, characterized in that, Before the machining preparation step, the grinding wheel for the microstructure array grinding of the workpiece surface is designed. The machining is carried out using the arc contour part of the grinding wheel, with the arc contour radius R of the grinding wheel being... w The calculation formula is: Where D is the depth of the microstructure and W is the width of the microstructure.

10. The method for processing microstructures on the surface of a workpiece according to claim 9, characterized in that, The grinding wheel is a grinding tool made of non-metallic crystalline abrasive and a binder.

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