Cutting force prediction method, system, equipment and medium for ultra-precision machining of titanium alloy

Abstract

The present invention provides a cutting force prediction method, system, equipment and medium for ultra-precision machining of titanium alloys. The method uses a diamond tool to perform scraping experiments on titanium alloy workpieces at different cutting depths, obtains the springback corresponding to different cutting depths, and establishes a springback force prediction model. The prefabricated titanium alloy thin-walled workpiece is subjected to turning force measurement experiments at different cutting depths to obtain the corresponding main cutting force and thrust and establish a shear force prediction model. The cutting force prediction model is then obtained according to the cutting force calculation formula determined by the ultra-precision turning system structure as well as the springback force prediction model and the shear force prediction model. The method also substitutes the cutting depth and width of the thin-walled workpiece obtained by discretizing the cutting area of ​​the titanium alloy workpiece to be processed into the cutting force prediction model to obtain a discretized cutting force prediction model. The method can efficiently and accurately predict the cutting force, is easy to be integrated into an intelligent cutting system, improves machining accuracy, reduces tool wear, and has high application value.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-precision machining of titanium alloys, and in particular to a method, system, computer equipment and storage medium for predicting cutting force during ultra-precision machining of titanium alloys taking surface springback into consideration. Background Art

[0002] Titanium alloys have the advantages of high strength, high temperature resistance, and corrosion resistance. They are widely used in biomedicine, aerospace and other fields. However, due to their low thermal conductivity, strong chemical activity, and small elastic modulus and other material properties, titanium alloys are difficult to process. Titanium alloy precision parts are processed using ultra-precision diamond cutting technology. Therefore, reducing tool wear and improving surface quality have always been difficult problems that need to be solved in ultra-precision turning of titanium alloys. Cutting force is closely related to tool wear and surface quality. Predicting cutting force can indirectly predict surface quality and tool life, and is an important basis for optimizing processing parameters. At the same time, proposing an effective cutting force prediction method is also a prerequisite for building a force feedback intelligent manufacturing system.

[0003] The existing cutting force evaluation methods for titanium alloys mainly include experimental instrument measurement, finite element simulation and human experience prediction. However, the existing cutting force evaluation methods not only fail to consider the non-negligible influence of the springback caused by the elastic deformation of the material surface during the actual cutting process on the cutting force, but also the cutting force prediction process is cumbersome and has large errors. There are also certain application defects: the experimental instrument measurement equipment is expensive, the instrument measurement accuracy depends on the accuracy of the equipment hardware conditions and the installation process, and the sensor is very easy to be contaminated and damaged during use, so that the dynamometer measurement will produce errors. Adding a dynamometer device will reduce the system stiffness, aggravate the tool vibration, and then destroy the quality of the machined surface, and cause the deviation of the measured force signal, and the measurement result has a certain error; at the same time, the finite element simulation process is relatively complicated, and usually requires a lot of time and computer resources for simulation calculations, which is not only inefficient, but also the material parameters have a great influence on the prediction results. It also has a certain degree of human subjectivity, and the predicted cutting force has no value for application in processing. Therefore, it is urgent to provide a reliable technical means that takes into account the springback of the cutting surface and can accurately measure the cutting force. Summary of the invention

[0004] The purpose of the present invention is to provide a method for predicting the cutting force of ultra-precision machining titanium alloy. A mathematical model between machining parameters, springback and cutting force is established through experimental methods, so that the cutting force can be predicted by cutting parameters before ultra-precision cutting. This method can not only effectively make up for the application defects of existing cutting force prediction methods, but also is efficient and accurate. It can also be effectively integrated into a force feedback intelligent cutting system, thereby improving machining accuracy and reducing tool wear, and has high application value.

[0005] In order to achieve the above objectives, it is necessary to provide a method, system, computer equipment and storage medium for predicting cutting force in ultra-precision machining of titanium alloy in response to the above technical problems.

[0006] In a first aspect, an embodiment of the present invention provides a method for predicting cutting force of ultra-precision machining titanium alloy, the method comprising the following steps:

[0007] A diamond tool is used to perform a scraping experiment on a titanium alloy workpiece at different cutting depths to obtain the springback amount corresponding to the different cutting depths, and a springback force prediction model is established based on the springback amount;

[0008] A turning force measurement experiment at different cutting depths is carried out on a prefabricated titanium alloy thin-walled workpiece using a diamond tool to obtain the main cutting force and thrust force corresponding to the different cutting depths, and a shear force prediction model is established based on the thrust force and main cutting force; the titanium alloy thin-walled workpiece is a long strip titanium alloy workpiece with an arc processing surface whose surface to be processed is consistent with the arc shape of the tool tip of the diamond tool;

[0009] According to the structure of the ultra-precision turning system, a cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloy is determined, and a cutting force prediction model is obtained according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model;

[0010] The cutting area of ​​the titanium alloy workpiece to be processed is discretized by the ultra-precision turning system to obtain a preset number of thin-walled workpieces, and the cutting depth and width of each thin-walled workpiece are substituted into the cutting force prediction model to obtain a discretized cutting force prediction model.

[0011] Furthermore, before the step of using a diamond tool to perform a scraping experiment on a titanium alloy workpiece at different cutting depths, the method further includes:

[0012] The titanium alloy workpiece processing parameters are obtained through preset experiments; the titanium alloy workpiece processing parameters include the titanium alloy workpiece elastic modulus, cutting friction coefficient, tool geometric parameters, shear angle and friction angle.

[0013] Furthermore, the step of obtaining the titanium alloy workpiece processing parameters through a preset experiment includes:

[0014] Pressing a diamond indenter into the surface of a titanium alloy workpiece to perform a nanoindentation experiment to obtain the elastic modulus of the titanium alloy workpiece;

[0015] Placing a pressed diamond slider on the surface of a titanium alloy workpiece to conduct a plane friction experiment, and using a plane friction coefficient tester to measure the cutting friction coefficient;

[0016] Observe the diamond tool through an atomic force microscope to obtain the tool geometric parameters; the tool geometric parameters include tool tip arc radius, tool rake angle, tool back angle and tool tip arc wrap angle;

[0017] According to the cutting friction coefficient and the tool rake angle, the shear angle and the friction angle are obtained; the shear angle and the friction angle are expressed as:

[0018]

[0019] Where φ and β represent the shear angle and friction angle respectively; u r and α represent the friction coefficient and tool rake angle, respectively.

[0020] Furthermore, the step of performing a scraping experiment at different cutting depths on a titanium alloy workpiece using a diamond tool to obtain the springback amounts corresponding to the different cutting depths, and establishing a springback force prediction model according to the springback amounts includes:

[0021] Using diamond tools to perform ultra-precision cutting of titanium alloy workpieces, micro grooves of different depths are machined on the surface of the titanium alloy workpiece according to different cutting depths to obtain scraped groove workpieces;

[0022] The scraped groove workpiece is photographed using a white light interferometer to obtain an actual cutting depth of the scraped groove workpiece, and a corresponding springback amount is calculated based on the actual cutting depth;

[0023] According to the cutting depth and the corresponding springback amount, a first corresponding relationship is obtained; the first corresponding relationship is expressed as:

[0024] h e =k1t c

[0025] Among them, h e and t c They represent springback and cutting depth respectively; k1 represents h e With t c The slope of the linear trend;

[0026] Substitute the rebound amount in the first corresponding relationship into the preset rebound force calculation formula to obtain the rebound force prediction model; the preset rebound force calculation formula is:

[0027]

[0028] Where, E represents the elastic modulus of the titanium alloy workpiece; κ represents the back angle of the diamond tool; h e represents the springback amount; y represents the cutting length; F spr Indicates rebound force.

[0029] Furthermore, the step of using a diamond tool to perform a turning force measurement experiment at different cutting depths on a prefabricated titanium alloy thin-walled workpiece to obtain the main cutting force and thrust force corresponding to the different cutting depths, and establishing a shear force prediction model based on the thrust force and main cutting force includes:

[0030] Use a dynamometer to obtain the main cutting force and thrust force corresponding to different cutting depths during the cutting process;

[0031] According to the cutting depth and the corresponding main cutting force and thrust, the corresponding second corresponding relationship and third corresponding relationship are obtained; the second corresponding relationship is expressed as:

[0032] F′ c =k2t c

[0033] Among them, F′ c and t c Respectively represent the main cutting force and cutting depth; k2 represents F' c With t c The slope of the linear trend;

[0034] The third corresponding relationship is expressed as:

[0035] F′ t =k3t c

[0036] Among them, F′ t and t c Respectively represent thrust and cutting depth; k3 represents F′ t With t c The slope of the linear trend;

[0037] Substitute the main cutting force in the second corresponding relationship and the thrust force in the third corresponding relationship into the preset shear force calculation formula to obtain the shear force prediction model; the preset shear force calculation formula is:

[0038]

[0039] In the formula,

[0040]

[0041] Among them, F′ t and F′ c Represent thrust and main cutting force respectively; τ shear and F shear represents shear stress and shear force respectively; w represents workpiece width; R, θ and φ represent the tool tip radius, tool tip angle and shear angle of the diamond tool respectively; h represents the tool tip radius, tool tip angle and shear angle of the diamond tool respectively; e and t c Represent the springback amount and cutting depth respectively.

[0042] Furthermore, the step of obtaining the cutting force prediction model according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model comprises:

[0043] Substitute the rebound force in the rebound force prediction model and the shear force in the shear force prediction model into the cutting force calculation formula to obtain the cutting force prediction model; the cutting force calculation formula is:

[0044]

[0045] Where α and κ represent the tool rake angle and tool clearance angle respectively; u r and φ represent the cutting friction coefficient and shear angle respectively; F spr and F shear Represents rebound force and shear force respectively; F″ t and F″ c They are respectively represented as the thrust force and main cutting force of titanium alloy thin-walled workpiece at different cutting depths.

[0046] Furthermore, the discretized cutting force prediction model is expressed as:

[0047]

[0048] Among them, w i represents the width of the i-th thin-walled workpiece after discretization; N represents the number of discretized thin-walled workpieces; and represent the thrust and main cutting force of the i-th strip area, respectively, and F t and F c They represent the thrust and main cutting forces of N strip areas respectively; R represents the radius of the diamond tool tip; t c Indicates the cutting depth.

[0049] In a second aspect, an embodiment of the present invention provides a cutting force prediction system for ultra-precision machining of titanium alloy, the system comprising:

[0050] The first model building module is used to perform a scraping experiment at different cutting depths on a titanium alloy workpiece using a diamond tool, obtain the springback amount corresponding to the different cutting depths, and establish a springback force prediction model based on the springback amount;

[0051] The second model building module is used to perform turning force measurement experiments at different cutting depths on a prefabricated titanium alloy thin-walled workpiece using a diamond tool to obtain the main cutting force and thrust force corresponding to the different cutting depths, and establish a shear force prediction model based on the thrust force and main cutting force; the titanium alloy thin-walled workpiece is a long strip titanium alloy workpiece with an arc processing surface whose surface to be processed is consistent with the arc shape of the tool tip of the diamond tool;

[0052] The third model building module is used to determine the cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloy according to the ultra-precision turning system structure, and obtain the cutting force prediction model according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model;

[0053] The fourth model building module is used to discretize the cutting area of ​​the titanium alloy workpiece to be processed through the ultra-precision turning system to obtain a preset number of thin-walled workpieces, and substitute the cutting depth and width of each thin-walled workpiece into the cutting force prediction model to obtain a discretized cutting force prediction model.

[0054] In a third aspect, an embodiment of the present invention further provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0055] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0056] The above-mentioned application provides a method, system, computer equipment and storage medium for predicting the cutting force of ultra-precision machining titanium alloys. Through the method, a diamond tool is used to perform a scraping experiment on a titanium alloy workpiece at different cutting depths to obtain the springback corresponding to different cutting depths, and a springback force prediction model is established according to the springback amount. A diamond tool is used to perform a turning force measurement experiment on a prefabricated titanium alloy thin-walled workpiece at different cutting depths to obtain the main cutting force and thrust corresponding to different cutting depths. A shear force prediction model is established according to the thrust and the main cutting force. Then, according to the structure of the ultra-precision turning system, a cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloys is determined, and a cutting force prediction model is obtained according to the cutting force calculation formula, the springback force prediction model and the shear force prediction model. In addition, a technical solution is provided for discretizing the cutting area of ​​the titanium alloy workpiece to be processed by the ultra-precision turning system to obtain a preset number of thin-walled workpieces, and substituting the cutting depth and width of each thin-walled workpiece into the cutting force prediction model to obtain a discretized cutting force prediction model. Compared with the existing technology, this cutting force prediction method for ultra-precision machining of titanium alloys establishes a mathematical model between machining parameters, springback and cutting force through experiments, which effectively makes up for the application defects of existing cutting force prediction schemes. It not only realizes the efficient and accurate prediction of the cutting force of ultra-precision cutting of titanium alloys through cutting parameters before ultra-precision cutting, but also is easy to integrate into the force feedback intelligent cutting system, thereby improving machining accuracy and reducing tool wear, and has high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1Schematic diagram of experimental equipment for ultra-precision machining of titanium alloy in an embodiment of the present invention;

[0058] Figure 2 is a cutting schematic diagram of ultra-precision machining of titanium alloy in an embodiment of the present invention;

[0059] Figure 3 This is the process architecture intention of the ultra-precision machining titanium alloy cutting force prediction in the embodiment of the present invention;

[0060] Figure 4 1 is a schematic flow chart of a method for predicting cutting force of ultra-precision machining titanium alloy in an embodiment of the present invention;

[0061] Figure 5 is an optical image of the three-dimensional profile of the groove obtained by the groove scraping experiment in an embodiment of the present invention;

[0062] Figure 6 Schematic diagram of the geometric relationship between cutting depth and springback in an embodiment of the present invention;

[0063] Figure 7 is a schematic diagram of a first corresponding relationship between cutting depth and springback amount in an embodiment of the present invention;

[0064] Figure 8 is a schematic diagram of a nanoindentation experiment in an embodiment of the present invention;

[0065] Fig. 9 Schematic diagram of a plane friction experiment in an embodiment of the present invention;

[0066] Fig.10 Schematic diagram of the shape of a titanium alloy thin-walled workpiece in an embodiment of the present invention;

[0067] Fig.11 Schematic diagram of the second corresponding relationship between cutting depth and main cutting force, and the third corresponding relationship between cutting depth and thrust force in an embodiment of the present invention;

[0068] Fig.12 is a schematic diagram of discretization processing of cutting area in an embodiment of the present invention;

[0069] Fig.13 is a schematic diagram of the structure of a cutting force prediction system for ultra-precision machining titanium alloy in an embodiment of the present invention;

[0070] Fig.14 It is a diagram of the internal structure of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0071] In order to make the purpose, technical scheme and beneficial effects of the present application clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the embodiments described below are part of the embodiments of the present invention and are only used to illustrate the present invention, but are not used to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] Ultra-precision cutting technology such as Figure 1 As shown in the figure, the workpiece is clamped on an ultra-precision machine tool. The spindle C carries the clamped workpiece through a vacuum suction cup and can move in the X and Y directions and rotate in the XY plane. The tool loaded on the B axis can translate in the Z direction and rotate in the XZ plane. By controlling the joint movement of the tool and the workpiece, a surface structure with specific shape characteristics can be processed. The shape accuracy and surface roughness of the microstructure surface can reach the sub-micron level and nanometer level respectively. The processing scale of ultra-precision machining is generally from a few microns to tens of microns, and titanium alloy has the characteristic of low elastic modulus. During ultra-precision cutting, the machined surface of the material is very likely to undergo elastic deformation, resulting in deformation such as Figure 2 The micron-scale rebound (h e ), and the springback force on the machining surface acts on the tool, causing severe friction with the tool back face, causing back face wear, and the springback of the material increases with the increase of cutting depth, and the influence of cutting force also increases accordingly. Therefore, the influence of cutting springback of titanium alloy on cutting force cannot be ignored.

[0073] The present invention provides a method for ultra-precision cutting of titanium alloy based on the fact that the springback of titanium alloy will affect the cutting force. Figure 3 As shown, on the basis of considering the surface springback, a mathematical model between machining parameters, springback amount and cutting force is established through experimental analysis, thereby realizing a method for predicting cutting force of ultra-precision machining titanium alloy, which can accurately predict cutting force based on cutting parameters before ultra-precision cutting. The following embodiments will explain the method for predicting cutting force of ultra-precision machining titanium alloy of the present invention in detail.

[0074] In one embodiment, Figure 4 As shown, a method for predicting cutting force of ultra-precision machining titanium alloy is provided, comprising the following steps:

[0075] S11. Performing a scraping experiment at different cutting depths on a titanium alloy workpiece using a diamond tool to obtain the springback corresponding to the different cutting depths, and establishing a springback force prediction model based on the springback; wherein the springback can be understood as the elastic deformation generated during ultra-precision cutting of titanium alloy, and acts on the tool in the form of springback force, such as Figure 2 As shown, when the tool rake angle is α, the tool back angle is κ, the shear angle is φ, and the cutting depth is t c, and when the cutting speed is V, the amount of springback generated on the machined surface is h e The corresponding rebound force, shear force, thrust force and main cutting force are F spr 、F shear 、F t and F c .

[0076] The purpose of setting different cutting depths in the scraping experiment is to obtain the springback data corresponding to different cutting depths, so as to obtain the linear relationship between the cutting depth and the springback. Specifically, the step of using a diamond tool to perform a scraping experiment on a titanium alloy workpiece at different cutting depths to obtain the springback corresponding to different cutting depths, and establishing a springback force prediction model according to the springback includes:

[0077] Using diamond tools to perform ultra-precision cutting of titanium alloy workpieces, micro grooves of different depths are machined on the surface of the titanium alloy workpiece according to different cutting depths to obtain scraped groove workpieces;

[0078] The scraped groove workpiece is photographed by a white light interferometer to obtain the actual cutting depth of the scraped groove workpiece, and the corresponding springback amount is calculated according to the actual cutting depth; wherein the scraped groove workpiece is photographed by a white light interferometer, and the following can be obtained: Figure 5 The three-dimensional optical profile of the groove shown in the figure directly obtains the actual cutting depth t′ of each groove on the surface of the scraped workpiece c , and then based on Figure 6 Actual cutting depth t′ shown c and the corresponding cutting depth (parameter) t c The corresponding springback is h e =t c -t′ c ; Based on multiple sets of scraping experiments with different cutting depths, multiple sets of cutting depths and corresponding springback data can be obtained;

[0079] According to the cutting depth and the corresponding springback amount, a first corresponding relationship is obtained; wherein the first corresponding relationship can be understood as a linear trend relationship between the cutting depth and the springback amount. Figure 7 As shown, the first corresponding relationship is expressed as:

[0080] h e =k1t c

[0081] Among them, h e and t c They represent springback and cutting depth respectively; k1 represents h e With t c The slope of the linear trend;

[0082] Substitute the rebound amount in the first corresponding relationship into the preset rebound force calculation formula to obtain the rebound force prediction model; the preset rebound force calculation formula is:

[0083]

[0084] Where, E represents the elastic modulus of the titanium alloy workpiece; κ represents the back angle of the diamond tool; h e represents the springback amount; y represents the cutting length; F spr Resilience

[0085] The rebound force prediction model can be understood as the rebound amount h in the preset rebound force calculation formula e Replaced by k1t c The obtained model will not be described here in detail;

[0086] It should be noted that the elastic modulus of the titanium alloy workpiece and the clearance angle of the diamond tool in the above-mentioned rebound force prediction model and the titanium alloy processing parameters involved in the following other prediction models can all be obtained through experiments or other methods; in order to meet the needs of using each prediction model and ensure the accuracy of the application, this embodiment preferably needs to obtain the titanium alloy processing parameters required for each prediction model before step S11. Specifically, before the step of performing a scraping experiment with different cutting depths on the titanium alloy workpiece using a diamond tool, it also includes:

[0087] The titanium alloy workpiece processing parameters are obtained through a preset experiment; the titanium alloy workpiece processing parameters include the titanium alloy workpiece elastic modulus, cutting friction coefficient, tool geometric parameters, shear angle and friction angle, and the specific acquisition steps are as follows:

[0088] A diamond indenter is pressed into the surface of a titanium alloy workpiece to perform a nanoindentation experiment to obtain the elastic modulus of the titanium alloy workpiece; wherein the nanoindentation experiment is as follows Figure 8 As shown, the corresponding operation process is as follows:

[0089] The diamond indenter is pressed into the surface of the titanium alloy workpiece. During the process of pressing in (loading) and withdrawing (unloading), the instrument records the load-indentation depth curve of the process, through which the elastic modulus of the titanium alloy workpiece can be obtained.

[0090] A pressurized diamond slider is placed on the surface of a titanium alloy workpiece to conduct a plane friction test, and a plane friction coefficient tester is used to measure the cutting friction coefficient; wherein, the principle of the plane friction test is as follows Fig. 9 As shown, a certain pressure is applied to the diamond slider on the titanium alloy workpiece to pull the diamond slider to slide at a constant speed, and a friction coefficient tester is used to measure the friction coefficient between the titanium alloy and the diamond as the cutting friction coefficient;

[0091] Observe the diamond tool through an atomic force microscope to obtain the tool geometric parameters; the tool geometric parameters include tool tip arc radius, tool rake angle, tool back angle and tool tip arc wrap angle;

[0092] According to the cutting friction coefficient and the tool rake angle, the shear angle and the friction angle are obtained; the shear angle and the friction angle are expressed as:

[0093]

[0094] Where φ and β represent the shear angle and friction angle respectively; u r and α represent the friction coefficient and tool rake angle, respectively.

[0095] S12, using a diamond tool to perform a turning force measurement experiment at different cutting depths on a prefabricated titanium alloy thin-walled workpiece, obtaining the main cutting force and thrust force corresponding to the different cutting depths, and establishing a shear force prediction model based on the thrust force and main cutting force; the titanium alloy thin-walled workpiece is a long strip titanium alloy workpiece with an arc processing surface whose surface to be processed is consistent with the arc shape of the tool tip of the diamond tool;

[0096] Among them, titanium alloy thin-walled workpieces such as Fig.10 The figure shows that the surface to be machined is pre-processed according to the arc of the diamond tool tip on the workpiece surface. The shape of the arc of the selected tool tip is consistent with the width w and meets the requirements. A titanium alloy workpiece with an arc-shaped cross section is prepared under the condition that the cutting thickness is equidistant under the condition; specifically, the steps of using a diamond tool to perform a turning force measurement experiment at different cutting depths on the prefabricated titanium alloy thin-walled workpiece to obtain the main cutting force and thrust force corresponding to the different cutting depths, and establishing a shear force prediction model based on the thrust force and the main cutting force include:

[0097] The dynamometer is used to obtain the main cutting force and thrust force corresponding to different cutting depths during the cutting process; the cutting process can be understood as cutting the above-mentioned titanium alloy thin-walled workpiece with a diamond tool, and the dynamometer is used to measure the force to obtain the thrust force F′ t and main cutting force F′ c At the same time, by changing the cutting depth t c Cutting is performed to obtain different cutting depths and thrusts F′ t , main cutting force F′ c ;

[0098] According to the cutting depth and the corresponding main cutting force and thrust, the corresponding second and third corresponding relationships are obtained; the second corresponding relationship can be understood as the linear relationship between the main cutting force and the cutting depth, and the third corresponding relationship can be understood as the linear relationship between the thrust force and the cutting depth, such as Fig.11 As shown, the second corresponding relationship is expressed as:

[0099] F′ c =k2t c

[0100] Among them, F′ c and t c Respectively represent the main cutting force and cutting depth; k2 represents F' c With t c The slope of the linear trend;

[0101] The third corresponding relationship is expressed as:

[0102] F′ t =k3t c

[0103] Among them, F′ t and t c Respectively represent thrust and cutting depth; k3 represents F′ t With t c The slope of the linear trend;

[0104] Substitute the main cutting force in the second corresponding relationship and the thrust force in the third corresponding relationship into the preset shear force calculation formula to obtain the shear force prediction model; the preset shear force calculation formula is:

[0105]

[0106] In the formula,

[0107]

[0108] Among them, F′ t and F′ c Represent thrust and main cutting force respectively; τ shear and F shear represents shear stress and shear force respectively; w represents workpiece width; R, θ and φ represent the tool tip radius, tool tip angle and shear angle of the diamond tool respectively; h represents the tool tip radius, tool tip angle and shear angle of the diamond tool respectively; e and t c Represent the springback amount and cutting depth respectively.

[0109] It should be noted that the shear force prediction model can be understood as replacing the main cutting force and thrust force in the preset shear force calculation formula with k2t in the second corresponding relationship respectively. c and k3t in the third corresponding relationship c The model is obtained, which will not be described here;

[0110] S13, according to the structure of the ultra-precision turning system, determine the cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloy, and obtain a cutting force prediction model according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model. The specific steps include:

[0111] Substitute the rebound force in the rebound force prediction model and the shear force in the shear force prediction model into the cutting force calculation formula to obtain the cutting force prediction model; the cutting force calculation formula is:

[0112]

[0113] Where α and κ represent the tool rake angle and tool clearance angle respectively; u r and φ represent the cutting friction coefficient and shear angle respectively; F spr and F shear Represents rebound force and shear force respectively; F″ t and F″ c They are respectively represented as the thrust force and main cutting force of titanium alloy thin-walled workpiece at different cutting depths.

[0114] S14, discretizing the cutting area of ​​the titanium alloy workpiece to be processed by the ultra-precision turning system to obtain a preset number of thin-walled workpieces, and substituting the cutting depth and width of each thin-walled workpiece into the cutting force prediction model to obtain a discretized cutting force prediction model; wherein the discretization of the cutting area is as follows: Fig.12 The figure can be understood as dividing the cutting area with a width of L into N equal parts with a width of w. i =L / N and the cutting depth is The cutting process of thin-walled workpieces;

[0115] The discretized cutting force prediction model is expressed as:

[0116]

[0117] Among them, w i represents the width of the i-th thin-walled workpiece after discretization; N represents the number of discretized thin-walled workpieces; and represent the thrust and main cutting force of the i-th strip area, respectively, and F t and F c They represent the thrust and main cutting forces of N strip areas respectively; R represents the radius of the diamond tool tip; t c Indicates the cutting depth.

[0118] The embodiment of the present application uses a diamond tool to perform scraping experiments on a titanium alloy workpiece at different cutting depths, obtains the springback amount corresponding to different cutting depths and establishes a springback force prediction model, and performs turning force measurement experiments on a prefabricated titanium alloy thin-walled workpiece at different cutting depths to obtain the corresponding main cutting force and thrust and establish a shear force prediction model. Then, according to the cutting force calculation formula determined by the ultra-precision turning system structure, as well as the springback force prediction model and the shear force prediction model, a cutting force prediction model is obtained, as well as a method for obtaining a discretized cutting force prediction model by substituting the cutting depth and width of a thin-walled workpiece obtained by discretizing the cutting area of ​​the titanium alloy workpiece to be processed into the cutting force prediction model. A mathematical model between processing parameters, springback amount and cutting force is established based on a preset experimental method, so that the cutting force can be predicted by cutting parameters before ultra-precision cutting. Compared with the prior art, it can not only efficiently and accurately predict the cutting force, but also is easy to integrate into a force feedback intelligent cutting system, thereby improving processing accuracy and reducing tool wear, and has a high application value.

[0119] It should be noted that although the steps in the above flowchart are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders.

[0120] In one embodiment, Fig.13 As shown, a cutting force prediction system for ultra-precision machining titanium alloy is provided, and the system comprises:

[0121] The first model building module 1 is used to perform a scraping experiment at different cutting depths on a titanium alloy workpiece using a diamond tool, obtain the springback amount corresponding to the different cutting depths, and establish a springback force prediction model based on the springback amount;

[0122] The second model building module 2 is used to perform turning force measurement experiments at different cutting depths on a prefabricated titanium alloy thin-walled workpiece using a diamond tool to obtain the main cutting force and thrust force corresponding to the different cutting depths, and establish a shear force prediction model based on the thrust force and main cutting force; the titanium alloy thin-walled workpiece is a long strip titanium alloy workpiece with an arc processing surface whose surface to be processed is consistent with the arc shape of the tool tip of the diamond tool;

[0123] The third model building module 3 is used to determine the cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloy according to the ultra-precision turning system structure, and obtain the cutting force prediction model according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model;

[0124] The fourth model building module 4 is used to discretize the cutting area of ​​the titanium alloy workpiece to be processed through the ultra-precision turning system to obtain a preset number of thin-walled workpieces, and substitute the cutting depth and width of each thin-walled workpiece into the cutting force prediction model to obtain a discretized cutting force prediction model.

[0125] For the specific definition of a cutting force prediction system for ultra-precision machining titanium alloy, please refer to the definition of a cutting force prediction method for ultra-precision machining titanium alloy mentioned above, which will not be repeated here. Each module in the above-mentioned ultra-precision machining titanium alloy cutting force prediction system can be implemented in whole or in part through software, hardware and their combination. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0126] Fig.14 FIG. 1 shows an internal structure diagram of a computer device in an embodiment, and the computer device may specifically be a terminal or a server. Fig.14 As shown, the computer device includes a processor, a memory, a network interface, a display and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for predicting the cutting force of ultra-precision machining titanium alloy is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0127] It can be understood by those skilled in the art that Fig.14 The structure shown in the figure is only a block diagram of a part of the structure related to the present application scheme, and does not constitute a limitation on the computer device to which the present application scheme is applied. The specific computing device may include more or fewer components than shown in the figure, or combine certain components, or have the same component arrangement.

[0128] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the steps of the above method are implemented when the processor executes the computer program.

[0129] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0130] In summary, the cutting force prediction method and system for ultra-precision machining of titanium alloys provided in the embodiments of the present invention realizes the use of diamond tools to perform scraping experiments on titanium alloy workpieces at different cutting depths, obtain the springback amounts corresponding to different cutting depths, establish a springback force prediction model based on the springback amounts, and use diamond tools to perform turning force measurement experiments on prefabricated titanium alloy thin-walled workpieces at different cutting depths to obtain the main cutting force and thrust forces corresponding to different cutting depths, establish a shear force prediction model based on the thrust force and the main cutting force, and then determine the cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloys based on the structure of the ultra-precision turning system. The cutting force prediction model is obtained by using a measurement model and a shear force prediction model, and the cutting area of ​​the titanium alloy workpiece to be processed is discretized by an ultra-precision turning system to obtain a preset number of thin-walled workpieces, and the cutting depth and width of each thin-walled workpiece are substituted into the cutting force prediction model to obtain a discretized cutting force prediction model. The cutting force prediction method for ultra-precision machining of titanium alloys establishes a mathematical model between machining parameters, springback amount and cutting force based on a preset experimental method, which not only realizes efficient and accurate prediction of cutting force through cutting parameters before ultra-precision cutting, but also facilitates integration into a force feedback intelligent cutting system, thereby improving machining accuracy and reducing tool wear, and has high application value.

[0131] Each embodiment in this specification is described in a progressive manner, and the same or similar parts of each embodiment can be directly referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. It should be noted that the technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The above-mentioned embodiments only express several preferred implementation modes of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in the technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be regarded as the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be based on the protection scope of the claims.

Claims

1. A method for predicting cutting force in ultra-precision machining of titanium alloy, characterized in that: The method comprises the following steps: A diamond tool is used to perform a scraping experiment on a titanium alloy workpiece at different cutting depths to obtain the springback amount corresponding to the different cutting depths, and a springback force prediction model is established based on the springback amount; A turning force measurement experiment at different cutting depths is carried out on a prefabricated titanium alloy thin-walled workpiece using a diamond tool to obtain the main cutting force and thrust force corresponding to the different cutting depths, and a shear force prediction model is established based on the thrust force and main cutting force; the titanium alloy thin-walled workpiece is a long strip titanium alloy workpiece with an arc processing surface whose surface to be processed is consistent with the arc shape of the tool tip of the diamond tool; According to the structure of the ultra-precision turning system, a cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloy is determined, and a cutting force prediction model is obtained according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model; Discretizing the cutting area of ​​the titanium alloy workpiece to be processed by an ultra-precision turning system to obtain a preset number of thin-walled workpieces, and substituting the cutting depth and width of each thin-walled workpiece into the cutting force prediction model to obtain a discretized cutting force prediction model; The steps of performing a scraping experiment at different cutting depths on a titanium alloy workpiece using a diamond tool to obtain springback amounts corresponding to different cutting depths, and establishing a springback force prediction model based on the springback amounts include: Using diamond tools to perform ultra-precision cutting of titanium alloy workpieces, micro grooves of different depths are machined on the surface of the titanium alloy workpiece according to different cutting depths to obtain scraped groove workpieces; The scraped groove workpiece is photographed using a white light interferometer to obtain an actual cutting depth of the scraped groove workpiece, and a corresponding springback amount is calculated based on the actual cutting depth; According to the cutting depth and the corresponding springback amount, a first corresponding relationship is obtained; the first corresponding relationship is expressed as: in, and Respectively represent the springback amount and cutting depth; express The slope of the linear trend; Substitute the rebound amount in the first corresponding relationship into the preset rebound force calculation formula to obtain the rebound force prediction model; the preset rebound force calculation formula is: in, Indicates the elastic modulus of titanium alloy workpiece; Indicates the back angle of diamond tool; Indicates the amount of rebound; Indicates cutting length; Resilience The steps of using a diamond tool to perform a turning force measurement experiment at different cutting depths on a prefabricated titanium alloy thin-walled workpiece to obtain the main cutting force and thrust force corresponding to the different cutting depths, and establishing a shear force prediction model based on the thrust force and main cutting force include: Use a dynamometer to obtain the main cutting force and thrust force corresponding to different cutting depths during the cutting process; According to the cutting depth and the corresponding main cutting force and thrust, the corresponding second corresponding relationship and third corresponding relationship are obtained; the second corresponding relationship is expressed as: in, and They represent the main cutting force and cutting depth respectively; express and The slope of the linear trend; The third corresponding relationship is expressed as: in, and represent thrust force and cutting depth respectively; express and The slope of the linear trend; Substitute the main cutting force in the second corresponding relationship and the thrust force in the third corresponding relationship into the preset shear force calculation formula to obtain the shear force prediction model; the preset shear force calculation formula is: In the formula, in, and represent thrust force and main cutting force respectively; and denote shear stress and shear force, respectively; Indicates the width of the workpiece; , and They represent the tool tip radius, tool tip angle and shear angle of the diamond tool respectively; and Respectively represent the springback amount and cutting depth; The step of obtaining the cutting force prediction model according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model comprises: Substitute the rebound force in the rebound force prediction model and the shear force in the shear force prediction model into the cutting force calculation formula to obtain the cutting force prediction model; the cutting force calculation formula is: in, and Represent the tool rake angle and tool clearance angle respectively; and represent the cutting friction coefficient and shear angle respectively; and represent the rebound force and shear force respectively; and They are respectively expressed as the thrust force and main cutting force of titanium alloy thin-walled workpiece at different cutting depths; The discretized cutting force prediction model is expressed as: in, Represents the discrete The width of a thin-walled workpiece; Indicates the number of discretized thin-walled workpieces; and Respectively represent The thrust and main cutting forces in the strip area, and Respectively The thrust and main cutting forces in the strip area; Indicates the radius of the diamond tool tip arc; Indicates the cutting depth.

2. The method for predicting cutting force of ultra-precision machining titanium alloy according to claim 1, characterized in that: Before the step of using a diamond tool to perform a scraping experiment on a titanium alloy workpiece at different cutting depths, the method further includes: The titanium alloy workpiece processing parameters are obtained through preset experiments; the titanium alloy workpiece processing parameters include the titanium alloy workpiece elastic modulus, cutting friction coefficient, tool geometric parameters, shear angle and friction angle.

3. The method for predicting cutting force of ultra-precision machining titanium alloy according to claim 2, characterized in that: The step of obtaining the titanium alloy workpiece processing parameters through a preset experiment comprises: Pressing a diamond indenter into the surface of a titanium alloy workpiece to perform a nanoindentation experiment to obtain the elastic modulus of the titanium alloy workpiece; Placing a pressed diamond slider on the surface of a titanium alloy workpiece to conduct a plane friction experiment, and using a plane friction coefficient tester to measure the cutting friction coefficient; Observe the diamond tool through an atomic force microscope to obtain the tool geometric parameters; the tool geometric parameters include tool tip arc radius, tool rake angle, tool back angle and tool tip arc wrap angle; According to the cutting friction coefficient and the tool rake angle, the shear angle and the friction angle are obtained; the shear angle and the friction angle are expressed as: in, and denote the shear angle and friction angle respectively; and represent the friction coefficient and tool rake angle respectively.

4. A cutting force prediction system for ultra-precision machining of titanium alloy, characterized in that: The method for predicting cutting force of ultra-precision titanium alloy machining as claimed in claim 1 is applied, wherein the system comprises: The first model building module is used to perform a scraping experiment at different cutting depths on a titanium alloy workpiece using a diamond tool, obtain the springback amount corresponding to the different cutting depths, and establish a springback force prediction model based on the springback amount; The second model building module is used to perform turning force measurement experiments at different cutting depths on a prefabricated titanium alloy thin-walled workpiece using a diamond tool to obtain the main cutting force and thrust force corresponding to the different cutting depths, and establish a shear force prediction model based on the thrust force and main cutting force; the titanium alloy thin-walled workpiece is a long strip titanium alloy workpiece with an arc processing surface whose surface to be processed is consistent with the arc shape of the tool tip of the diamond tool; The third model building module is used to determine the cutting force calculation formula for ultra-precision cutting of thin-walled titanium alloy according to the ultra-precision turning system structure, and obtain the cutting force prediction model according to the cutting force calculation formula, the rebound force prediction model and the shear force prediction model; The fourth model building module is used to discretize the cutting area of ​​the titanium alloy workpiece to be processed through the ultra-precision turning system to obtain a preset number of thin-walled workpieces, and substitute the cutting depth and width of each thin-walled workpiece into the cutting force prediction model to obtain a discretized cutting force prediction model.

5. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 3 are implemented.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

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