Double-shearing-edge cutting tool and cutting edge design and optimization method thereof

Abstract

The invention provides a double-shearing-edge cutting tool and a cutting edge design and optimization method thereof, relates to the technical field of cutting tool cutting edge structure design, and aims to determine an optimal cutting edge curve and realize a smooth and continuous cutting edge structure by optimizing geometric parameters and basic configuration of double shearing edges and utilizing an orthogonal test design method and a cutting simulation technology. By means of the design, distribution of cutting force can be remarkably improved, the concentration effect of cutting heat is reduced, tool abrasion is effectively reduced, and the service life of a tool is prolonged; and meanwhile, the chip breaking effect and the chip removal efficiency of continuous chip cutting in the cutting process are improved, and the occurrence rate of cutting vibration and machining surface defects is reduced, so that higher machining precision and surface quality are achieved, and the cutting efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of cutting tool edge structure design technology, and more specifically, to a double shearing edge cutting tool and its edge design and optimization method. Background Technology

[0002] As one of the fundamental processes in modern manufacturing, machining technology is widely used in machinery, aerospace, automotive, and mold making. With the continuous development of advanced manufacturing technologies, higher demands are being placed on the performance of cutting tools. Cutting tools are the core components for achieving efficient and high-precision machining; their design and performance directly affect machining quality, production efficiency, and machining costs. In traditional cutting technologies, tool edge designs are mostly based on a single geometry and fixed parameters, making it difficult to simultaneously meet the requirements of efficient cutting and high surface quality. Furthermore, with the increasing demand for processing composite materials (such as carbon fiber composites and ceramic matrix composites), traditional single-edge cutting tools are gradually revealing many limitations in cutting force distribution, chip handling, and thermal stress control, making it difficult to meet the needs of modern machining technology development. Therefore, how to improve cutting efficiency, enhance surface quality, and reduce energy consumption during the cutting process by optimizing tool edge geometry design has become one of the current research hotspots in the field of cutting tools.

[0003] The shortcomings of existing cutting tools are mainly reflected in the following aspects: First, most traditional tools adopt a single shearing edge design, with a simple cutting edge shape that makes it difficult to effectively disperse the cutting force and heat generated during the cutting process, leading to accelerated tool wear and affecting service life and machining accuracy. Second, the single cutting edge design is prone to chip accumulation and cutting vibration when machining composite materials, thereby reducing cutting stability. In addition, existing tools lack targeted optimization in the design of cutting edge geometry parameters, making it difficult to balance machining efficiency and surface quality. For example, in some high-precision machining scenarios, tools with a single shearing edge design often fail to achieve a smooth machining surface and uniform material removal due to unreasonable cutting edge geometry, while in high-efficiency machining scenarios, the single cutting edge design can easily lead to excessive concentration of cutting heat, affecting machining stability and tool life. Summary of the Invention

[0004] To address the problems of abrupt cutting load changes, tool chipping, burr formation, and workpiece surface damage encountered by existing cutting tools when machining high-performance composite materials, particularly carbon fiber composites and ceramic matrix composites, this invention is proposed. This invention provides a double-shearing-edge cutting tool and its cutting edge design and optimization method.

[0005] According to one aspect of the present invention, a double-shearing-edge cutting tool and a method for designing and optimizing its cutting edge are provided, comprising:

[0006] Determine the design parameters and basic configuration of the cutting edge of the double shearing blade tool;

[0007] A coordinate system was established, and a three-dimensional right-angle cutting model was built based on ABAQUS / Explicit. The optimal geometric parameters were solved using the orthogonal experimental design method.

[0008] Based on the optimal parameters, the parametric equations of the first and second shearing blades are established respectively, the spatial coordinates of each key cutting point are determined, and the point set data of the optimal double shearing blade cutting edge curve are obtained.

[0009] All key points are arranged in order of their position on the double shearing edge, and the discrete coordinate points are connected into a smooth and continuous curve by numerical fitting method to form the cutting edge structure of the tool.

[0010] Furthermore, the cutting edge of the double shearing blade includes an lr edge and an le edge; the cutting edge radii are r and r, respectively. r and r e The central angle is θ, and the central angles corresponding to the cutting edge are respectively... And 2θ, the front face is tangent to the starting point of the edge of the lr cutting edge, and the tangency point is W; the ending point of the edge of the lr cutting edge is tangent to the starting point of the edge of the le cutting edge, and the tangency point is M; the ending point of the edge of the le cutting edge is tangent to the back face, and the tangency point is N.

[0011] Furthermore, the planar rectangular coordinate system is established based on the center positions of the two shearing edges;

[0012] Connect the centers of the two circles with a straight line, and take the midpoint of the line as the origin O of the coordinate system;

[0013] Let the X-axis coincide with the line connecting the center of the circle, and let the Y-axis be perpendicular to the X-axis; define the angle with the positive direction of the X-axis as the reference and the counterclockwise direction as the positive direction, thereby obtaining the plane rectangular coordinate system O–XY.

[0014] Furthermore, the optimal geometric parameters use the central angle θ and the offset distance D as optimization variables to generate n sets of geometric parameter combinations, and establish three-dimensional models for each combination to obtain the cutting response results under different parameter combinations;

[0015] The cutting response results include force values ​​in three directions: main cutting force, feed force, and back force.

[0016] Calculate the average cutting force and force fluctuation amplitude throughout the entire cutting process;

[0017] Calculate the standard deviation or coefficient of variation to quantify the stability of the cutting process;

[0018] The combination of geometric parameters with the highest overall score is taken as the optimal solution.

[0019] Furthermore, the comprehensive score is calculated as follows:

[0020]

[0021] Where S is the overall score. For the average cutting force, F c σ is the cutting force threshold, and σ is the standard deviation of the cutting force. c θ is the standard deviation threshold, θ is the central angle, θ0 is the reference central angle, and θ c D is the center angle tolerance, D is the offset distance, D0 is the reference offset distance, and D... c This is the offset distance tolerance.

[0022] Furthermore, the key cutting points include the intersection of the first shearing blade and the front cutting face, the intersection of the second shearing blade and the rear cutting face, and the transition connection point between the two shearing blades;

[0023] The geometric features of the first and second shearing blades are described using a rectangular coordinate system. When constructing the parametric equations of the first shearing blade, the coordinates of any point on the first shearing blade can be obtained by using trigonometric functions with the origin of the tool coordinate system as the reference.

[0024] The parametric equations for the second shearing blade are constructed based on the offset distance D. The second arc is positioned correctly through coordinate transformation to obtain the corresponding coordinates.

[0025] Furthermore, the parametric equations for the first shearing blade are as follows:

[0026]

[0027] Where (x) r ,y r ) is the coordinate of the cutting edge curve of the lr blade in a rectangular coordinate system;

[0028] The parametric equation for the second shear blade is as follows:

[0029] x e =r e sinθ2

[0030]

[0031] Where (x) e ,y e ) is the coordinate of the cutting edge curve of the blade in a rectangular coordinate system.

[0032] Furthermore, the least squares method is used to perform circular arc fitting on the two sets of coordinate points from the intersection of the rake face to the transition point and from the transition point to the intersection of the flank face, respectively, and finally the equation of the smooth and continuous double shearing edge curve is obtained.

[0033] Compared with existing technologies, this invention provides a dual-shear blade cutting tool and its cutting edge design and optimization method. By optimizing the geometric parameters and basic configuration of the dual shear blades, and utilizing orthogonal experimental design and cutting simulation technology, the optimal cutting edge curve is determined, achieving a smooth and continuous cutting edge structure. This design can significantly improve the distribution of cutting force, reduce the concentration effect of cutting heat, effectively reduce tool wear, and extend tool life. Simultaneously, it improves the chip breaking effect and chip removal efficiency of continuous chips during cutting, reduces the incidence of cutting vibration and surface defects, thereby achieving higher machining accuracy and surface quality, and improving cutting efficiency. By constructing a dual-shear blade structure, the load during cutting is released in stages, effectively alleviating the load abrupt change problem caused by the single curvature radius of traditional single shear blades. Simulation verification shows that the optimized combination of geometric parameters can reduce the cutting force fluctuation amplitude by approximately 15.34%, thus significantly improving the dynamic stability and controllability of the machining process. This staged shearing method exhibits excellent performance in machining difficult-to-machine materials such as composite materials, effectively suppressing typical defects such as tearing and delamination, and is suitable for high-precision cutting scenarios of high-performance composite materials. Attached Figure Description

[0034] 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. In the drawings:

[0035] Figure 1 This is a schematic diagram illustrating the structural principle of a double-shearing-edge cutting tool according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the geometric parameter relationship of a double shearing blade cutting tool according to an embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram of a tool cutting carbon fiber composite material according to an embodiment of the present invention.

[0038] Figure 4 This is a schematic diagram of the mechanical distribution of the cutting tool-workpiece contact area in a double shearing blade according to an embodiment of the present invention.

[0039] Figure 5 This is a cutting force curve generated by a single shearing edge cutting tool according to an embodiment of the present invention during the cutting of carbon fiber composite materials.

[0040] Figure 6 This is a cutting force curve generated by a double shearing blade cutting tool according to an embodiment of the present invention during the cutting of carbon fiber composite materials. Detailed Implementation

[0041] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is obvious that the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention; it should be understood that the present invention is not limited to the embodiments described herein.

[0042] Figure 1 This is a schematic diagram illustrating the structural principle of a double-shearing-edge cutting tool according to an embodiment of the present invention. Figure 1 As shown, a double-shearing-edge cutting tool and its cutting edge design and optimization method include:

[0043] S1. Determine the design parameters and basic configuration;

[0044] The cutting edge of a double-blade shearing tool is divided into two parts, the lr blade and the le blade, with cutting edge radii of r and r respectively. r and r e The central angle is θ, and the central angles corresponding to the cutting edge are respectively... And 2θ, the front face is tangent to the starting point of the cutting edge of lr, and the tangency point is W; the ending point of the cutting edge of lr is tangent to the starting point of the cutting edge of le, and the tangency point is M; the ending point of the cutting edge of le is tangent to the back face, and the tangency point is N.

[0045] S2. Establish a coordinate system and solve for the optimal geometric parameters based on ABAQUS cutting simulation;

[0046] First, determine the center positions of the two shearing edges, connect these two centers with a straight line, and take the midpoint of this line as the origin O of the coordinate system. Then, align the X-axis with the line connecting the centers, and perpendicular the Y-axis to the X-axis. Define the angles with the positive X-axis as the reference and the counterclockwise direction as the positive direction, thus obtaining a Cartesian coordinate system O–XY. If the positions of the two centers of the double shearing edges change, the origin O will change accordingly, but the directions of the coordinate axes will remain constant. This method of establishing a coordinate system not only accurately describes the position of the tool cutting edges but also facilitates subsequent adjustment and optimization of cutting parameters.

[0047] When building a 3D cutting model in the ABAQUS / Explicit environment, the first step is to model the actual cutting tool's double shearing edge geometry. When creating the tool geometry, key geometric parameters of the double shearing edge should be defined and controlled using parametric modeling methods. The most important parameters include the central angle θ and the offset distance D. If the tool geometry needs adjustment, the angle between the two arcs can be controlled by changing the value of the central angle θ, and the distance between the centers of the two arcs can be changed by adjusting the offset distance D. After establishing the parametric model, the geometry needs to be meshed and material properties defined. Since the cutting process is a high-speed dynamic process, an explicit solver should be selected for analysis. At this point, it is also important to ensure that the element type selection meets the requirements of large deformation analysis. During model setup, it should be ensured that the parametrically defined geometric dimensions are within a reasonable range. Typically, the central angle θ ranges from 30° to 60°, and the offset distance D ranges from 0.01mm to 0.08mm. This ensures the practicality of the tool geometry and the machining effect.

[0048] Furthermore, when constructing a three-dimensional solid workpiece model of CFRP composite materials, the anisotropic characteristics of the material need to be fully considered. When defining material properties, parameters such as elastic modulus E1, E2, E3, shear modulus G12, G13, G23, and Poisson's ratio v12, v13, v23 in different directions should be input. To accurately simulate the mechanical behavior and failure process of CFRP during cutting, a composite material constitutive model based on the Hashin failure criterion needs to be implemented through the VUMAT user subroutine. This subroutine needs to include the stress-strain relationship and strength parameters of the material. The program simulates the damage evolution process and the failure mechanism of composite materials. When the material is subjected to load, the program determines whether failure occurs based on the Hashin failure criterion, including tensile and compressive failure of fibers, tensile and compressive cracking of the matrix, and shear delamination between layers. Once the failure condition is met, the stiffness of the material will gradually degrade according to the predefined damage evolution law, thereby achieving accurate simulation of various failure mechanisms during the cutting process of composite materials. In this process, special attention should be paid to the calibration of material parameters and the rationality of the damage evolution law to ensure that the simulation results can truly reflect the cutting behavior of CFRP.

[0049] Furthermore, using the center angle θ and the value of D as optimization variables, an orthogonal experimental design method is employed to generate n sets of geometric parameter combinations. Based on each set of parameters, corresponding three-dimensional models are established, and batch cutting simulations are then performed to obtain cutting response results under different parameter combinations. When optimizing tool geometry parameters, the center angle θ and offset distance D of the double shearing edge are first determined as key optimization variables. When designing the orthogonal experimental scheme, it is necessary to reasonably divide the value ranges of these two parameters and determine the number of levels. Typically, the center angle θ is taken at 3 to 5 levels between 30° and 60°, and the offset distance D is taken at 3 to 5 levels between 0.01 mm and 0.08 mm. If the parameter combinations are generated according to the orthogonal experimental table... This requires utilizing ABAQUS's parametric modeling capabilities to construct corresponding 3D cutting models based on different parameter combinations. Once all models are built, a Python script should be written to automate the simulation process submission and result extraction, enabling batch execution of cutting simulation analysis. During simulation execution, it is crucial to focus on and record cutting response indicators such as the magnitude and fluctuation characteristics of cutting forces, chip morphology, surface finish, and material damage degree under each parameter set. To ensure the reliability of the simulation results, the consistency of mesh quality, boundary conditions, and solution settings for each model must also be ensured. Finally, by comparing and analyzing the cutting response results under different parameter combinations, a basis for determining the optimal geometric parameters can be provided.

[0050] Furthermore, cutting force data corresponding to each set of parameters is extracted from the simulation results, including force values ​​in three directions: main cutting force, feed force, and back force. When processing the cutting force data, the average cutting force and force fluctuation amplitude are calculated throughout the entire cutting process. The average cutting force reflects the overall stress level of the tool, while the force fluctuation amplitude characterizes the stability of the cutting process. For comprehensive comparative analysis, cutting force variation curves under different combinations of center angle θ and offset distance D are plotted to observe the influence of geometric parameters on cutting force. At the same time, the force value fluctuation range under each set of parameters is statistically analyzed, and the standard deviation or coefficient of variation is calculated to quantify the stability of the cutting process. After obtaining the force value data for all parameter combinations, an evaluation index system is established. Parameter combinations with smaller average cutting force and smaller force value fluctuation amplitude are considered the optimal choice, because smaller cutting force can reduce tool wear and workpiece deformation, while smaller force value fluctuation helps improve machining stability and surface quality. If the average cutting force and force value fluctuation cannot be optimal at the same time, the weight of each index is determined according to the actual machining requirements. The performance of different parameter combinations is comprehensively evaluated through weighted scoring, and finally, the geometric parameter combination with the highest comprehensive score is selected as the optimal solution. The overall score is calculated as follows:

[0051]

[0052] Where S is the overall score. For the average cutting force, F c σ is the cutting force threshold, and σ is the standard deviation of the cutting force. c θ is the standard deviation threshold, θ is the central angle, θ0 is the reference central angle, and θ c D is the center angle tolerance, D is the offset distance, D0 is the reference offset distance, and D... c This is the offset distance tolerance.

[0053] S3. Parametric Modeling and Structural Implementation of the Cutting Edge Curve

[0054] Based on the optimal parameters, parametric equations for the first and second shearing blades are established, and the coordinates of each key tangent point are defined. After determining the optimal center angle θ and offset distance D, a mathematical model of the double shearing edge is first established, describing the geometric characteristics of the first and second shearing blades using a Cartesian coordinate system. When constructing the parametric equations for the first shearing blade, the origin of the tool coordinate system is used as the reference, and the position of the arc in the Cartesian coordinate system is represented by the parameter lr. The range of values ​​for θ is determined by the starting and ending points of the arc. The coordinates (x, y, y) of any point on the first shearing blade can be obtained through trigonometric relationships. r ,y r To construct the parametric equations for the second shear blade, the influence of the offset distance D needs to be considered. The second arc is positioned correctly through coordinate transformation, and the position of a point on the arc is described by the parameter le, yielding the corresponding coordinates (x, y). e ,y e Once the parametric equations are established, the key focus is on determining the precise coordinates of several critical tangent points, including the intersection of the first shearing edge and the rake face, the intersection of the second shearing edge and the flank face, and the transition connection point between the two shearing edges. The coordinates of these feature points can be obtained by solving the parametric equations. The intersection points with the rake and flank faces are determined by the intersection relationship between the cutting edges and the tool surface, while the transition point between the two cutting edges is determined by the continuity condition of the tangents of the two circular arcs. Finally, a complete mathematical description of the planar profile of the double shearing edge is obtained, as shown below:

[0055] Based on the geometric principles of step S1, the parametric equations of the lr blade are obtained as follows:

[0056]

[0057] Where (x) r ,y r ) is the coordinate of the cutting edge curve of the lr blade in a rectangular coordinate system;

[0058] Based on the geometric principles of step S1, the parametric equations of the le blade are obtained as follows:

[0059] x e =r e sinθ2

[0060]

[0061] Where (x) e ,y e () represents the coordinates of the cutting edge curve of the le blade in a rectangular coordinate system;

[0062] The coordinates of the point W where the rake face and the cutting edge lr are tangent are (x1, y1);

[0063]

[0064] The coordinates of the point of tangency M between the cutting edges lr and le are (x2, y2);

[0065]

[0066] The coordinates of the point of tangency N between the cutting edge le and the back face are (x3, y3);

[0067]

[0068] After obtaining the point set data for the optimal double shearing edge curve, all key points are first arranged according to their positions on the double shearing edge, including the intersection with the rake face, feature points on the first shearing edge, the transition connection point between the two shearing edges, feature points on the second shearing edge, and the intersection with the flank face. After the point set is sorted, a numerical fitting method is used to connect the discrete coordinate points into a smooth and continuous curve. The first and second shearing edges are fitted with circular arcs to ensure the continuity of the tangent direction at the transition point. To ensure the accuracy of the edge curve, error analysis of the fitting results is required. The deviation between the fitted curve and the theoretical coordinate points is calculated. When the deviation exceeds the allowable range, the accuracy is improved by increasing the number of feature points or adjusting the fitting method. After obtaining a double shearing edge curve that meets the accuracy requirements, this curve is used as a reference. A complete tool edge structure is formed by the intersection of the rake face and the flank face. The inclination angles of the rake face and the flank face need to match the process requirements. To ensure the machinability of the edge structure, a smooth transition is adopted in the curve transition area to avoid stress concentration, while maintaining the balance between edge strength and cutting performance. Finally, a tool edge structure with the optimal double shearing edge curve characteristics is formed.

[0069] For the double shear edge curve, the least squares method is used for arc fitting. After the two arc segments are fitted, the continuity at the transition point is checked. The tangent direction of the two arc segments at the transition point is calculated to ensure that the tangent direction is continuous and smooth. If discontinuities or jumps are found at the transition point, the fitting parameters need to be adjusted or the number of sampling points near the transition point needs to be increased, and the fitting calculation is repeated until the continuity requirement is met. After the final fitting result is determined, the coordinates of any point on the fitted curve are calculated to form a continuous and smooth double shear edge curve equation.

[0070] This method addresses a double-shear structure consisting of a first shearing edge and a second shearing edge, sequentially positioned along the main cutting direction. It employs a piecewise circular arc fitting approach to extract the radius and center coordinates of the two edge curves. By analyzing the curvature changes of the two shearing edges, the geometric characteristics of the transition connection points, and their relative arrangement in the cutting path, a parametric characterization of the spatial morphology of the double-shearing edge is achieved. This method accurately describes the force transmission characteristics and edge sharpness under a double-shearing path, providing an efficient and reliable geometric modeling foundation for tool structure optimization and performance prediction.

[0071] By constructing a dual-shear blade structure, a tiered load release during the cutting process is achieved, effectively mitigating the sudden load change problem caused by the single curvature radius in traditional single-shear blades. Simulation verification shows that the optimized combination of geometric parameters can reduce the cutting force fluctuation amplitude by approximately 15.34%, thereby significantly improving the dynamic stability and controllability of the machining process. This tiered shearing method exhibits excellent performance in machining difficult-to-machine materials such as composite materials, effectively suppressing typical defects such as tearing and delamination, and is suitable for high-precision cutting scenarios of high-performance composite materials.

[0072] The dual-shear cutting tool proposed in this invention achieves graded shearing processing of composite materials by using an innovatively designed first shearing edge (lr edge) and second shearing edge (le edge) to work together to form a dual shearing structure. Figure 1 As shown, in the initial stage of cutting, the cutting edge lr pre-shears the material surface, causing controllable deformation of the fibers and releasing part of the initial load; subsequently, at the tangent point M, the cutting transitions to the cutting edge le for subsequent fine shearing. Figure 2 As shown, the double-arc transition structure between the two shearing blades, formed by setting differentiated radii of curvature and geometric parameters, ensures a smooth connection in the shearing process, thereby effectively reducing the risk of stress concentration and sudden load changes. Specifically, the LR blade and the LE blade have gradient differences in sharpness and radius of curvature design, which can be specifically configured according to the structural characteristics of the workpiece to meet the functional requirements of different shearing stages.

[0073] like Figure 5 , Figure 6Numerical simulation results of the cutting process shown indicate that, compared with the traditional single-shear blade structure, the double-shear blade structure of this invention can reduce the maximum cutting force by approximately 48.08% and the average cutting force by approximately 38.52%. While effectively controlling the material deformation path and mitigating cutting impact, it also improves tool life and machined surface quality. This structure is particularly suitable for applications such as aerospace and precision instruments, where the processing quality requirements for composite materials are extremely high.

[0074] In summary, a double-shearing-edge cutting tool and its cutting edge design and optimization method based on embodiments of the present invention have been elucidated. By optimizing the geometric parameters and basic configuration of the double-shearing edges, and utilizing orthogonal experimental design methods and cutting simulation technology, the optimal cutting edge curve is determined, achieving a smooth and continuous cutting edge structure. This significantly improves the distribution of cutting forces, reduces the concentration effect of cutting heat, and effectively reduces tool wear. Simultaneously, it improves chip breaking efficiency and chip removal efficiency during cutting, reduces cutting vibration and the incidence of surface defects, thereby achieving higher machining accuracy and surface quality, improving cutting efficiency, and extending tool life.

[0075] Here, those skilled in the art will understand that the specific operations of each step in the above-described method for designing and optimizing a double-shearing cutting tool and its cutting edge have been referenced above. Figures 1 to 6 The description of a double shearing edge cutting tool and its edge design and optimization method is detailed here, and therefore, its repeated description will be omitted.

[0076] In summary, a double-shearing-edge cutting tool and its cutting edge design and optimization method based on embodiments of the present invention have been elucidated. By optimizing the geometric parameters and basic configuration of the double shearing edges, and utilizing orthogonal experimental design methods and cutting simulation technology, the optimal cutting edge curve is determined, achieving a smooth and continuous cutting edge structure. This design can significantly improve the distribution of cutting forces, reduce the concentration effect of cutting heat, effectively reduce tool wear, and extend tool life. Simultaneously, it improves the chip breaking effect and chip removal efficiency of continuous chips during cutting, reduces the incidence of cutting vibration and surface defects, thereby achieving higher machining accuracy and surface quality, and improving cutting efficiency.

Claims

1. A double shear cutting tool and its edge design and optimization method, characterized in that: determining the design parameters and basic configuration of the edge of the double shear cutting tool; establishing a coordinate system and a three-dimensional right-angle cutting model based on ABAQUS / Explicit, and solving the optimal geometric parameters by using the orthogonal experimental design method; based on the optimal parameters, establishing the parameter equations of the first shear edge and the second shear edge respectively, determining the coordinates of each key point, and obtaining the point set data of the optimal double shear edge curve; arranging all the key points in the order of their positions on the double shear edge, connecting the discrete coordinate points into a smooth and continuous curve by using the numerical fitting method, and forming the edge structure of the cutting tool; the plane right-angle coordinate system is established based on the center positions of the two shear edges; connecting the two centers into a straight line, and taking the midpoint of the straight line as the coordinate origin O; making the X-axis coincide with the center line, and making the Y-axis perpendicular to the X-axis; defining the angle with the positive direction of the X-axis as the reference, and defining the counterclockwise direction as the positive direction, thereby obtaining the plane right-angle coordinate system O-XY; the optimal geometric parameters take the central angle θ and the offset distance D as the optimization variables, generate n sets of geometric parameter combinations, establish three-dimensional models respectively, and obtain the cutting response results under different parameter combinations; the cutting response results include the force values in the three directions of the main cutting force, the feed force and the back force; calculating the average cutting force and the fluctuation amplitude of the force in the whole cutting process; calculating the standard deviation or the coefficient of variation to quantify the stability of the cutting process; and taking the geometric parameter combination with the highest comprehensive score as the optimal scheme; the calculation of the comprehensive score is shown in the following formula: the key points include the intersection of the first shear edge and the rake face, the intersection of the second shear edge and the relief face, and the transition connection point of the two shear edges; the geometric characteristics of the first shear edge and the second shear edge are described by using the plane right-angle coordinate system; when the parameter equation of the first shear edge is constructed, the coordinates of any point on the first shear edge can be obtained through the trigonometric function relationship based on the origin of the tool coordinate system; the parameter equation of the second shear edge is constructed based on the offset distance D, and the second circular arc is positioned to the correct position through coordinate transformation to obtain the corresponding coordinates. 2.The double shear cutting tool and its edge design and optimization method according to claim 1, wherein: the plane right-angle coordinate system is established based on the center positions of the two shear edges; connecting the two centers into a straight line, and taking the midpoint of the straight line as the coordinate origin O; making the X-axis coincide with the center line, and making the Y-axis perpendicular to the X-axis; defining the angle with the positive direction of the X-axis as the reference, and defining the counterclockwise direction as the positive direction, thereby obtaining the plane right-angle coordinate system O-XY. 3.The double shear cutting tool and its edge design and optimization method according to claim 1 or 2, wherein: the optimal geometric parameters take the central angle θ and the offset distance D as the optimization variables, generate n sets of geometric parameter combinations, establish three-dimensional models respectively, and obtain the cutting response results under different parameter combinations; the cutting response results include the force values in the three directions of the main cutting force, the feed force and the back force; calculating the average cutting force and the fluctuation amplitude of the force in the whole cutting process; calculating the standard deviation or the coefficient of variation to quantify the stability of the cutting process; and taking the geometric parameter combination with the highest comprehensive score as the optimal scheme; the calculation of the comprehensive score is shown in the following formula: the key points include the intersection of the first shear edge and the rake face, the intersection of the second shear edge and the relief face, and the transition connection point of the two shear edges. 4.The double shear cutting tool and its edge design and optimization method according to claim 1 or 3, wherein: the geometric characteristics of the first shear edge and the second shear edge are described by using the plane right-angle coordinate system; when the parameter equation of the first shear edge is constructed, the coordinates of any point on the first shear edge can be obtained through the trigonometric function relationship based on the origin of the tool coordinate system; the parameter equation of the second shear edge is constructed based on the offset distance D, and the second circular arc is positioned to the correct position through coordinate transformation to obtain the corresponding coordinates. 5.The double shear cutting tool and its edge design and optimization method according to claim 1 or 4, wherein: the parameter equation of the first shear edge is as follows: the parameter equation of the second shear edge is as follows: the least square method is used to fit the two sets of coordinate points from the intersection of the first shear edge and the rake face to the transition point and from the transition point to the intersection of the second shear edge and the relief face, and finally the smooth and continuous double shear edge curve equation is obtained.

2. A double shear cutting tool and its edge design and optimization method according to claim 1, characterized in that, The double shear edge tool edge includes lr edge and le edge; edge radius is r respectively r and r e , central angle is θ, edge corresponding central angle is and 2θ respectively, rake face is tangent to lr edge edge start point, tangent point is W; lr edge edge end point is tangent to le edge edge start point, tangent point is M, le edge edge end point is tangent to relief face, tangent point is N.

3. A dual shear edge cutting tool and its edge design and optimization method according to claim 2, characterized in that, 6.A computer program product, comprising a computer program stored on a computer readable medium and loadable into the internal memory of a digital computer, comprising software code portions, when said product is run on a computer, for performing the method of any one of claims 1 to 8. 7.A computer readable medium having stored the computer program of claim 6. ​ 4. A dual shear edge cutting tool and its edge design and optimization method according to claim 3, characterized in that, ​ ​ ​ ​ ​ 5. A dual shear edge cutting tool and its edge design and optimization method according to claim 4, characterized in that, ​ wherein S is a comprehensive score value, F is an average cutting force, c σ is a cutting force threshold value, σ is a cutting force standard deviation, σ c is a standard deviation threshold value, θ is a central angle, θ0 is a reference central angle, θ c is a central angle tolerance, D is a bias distance, D0 is a reference bias distance, D c is a bias distance tolerance.

6. A dual shear edge cutting tool and its edge design and optimization method according to claim 5, characterized in that, ​ ​ ​ 7. A dual shear edge cutting tool and its edge design and optimization method according to claim 6, characterized in that, ​ where (x r ,y r ) are coordinates of the cutting edge curve of the lr blade in the rectangular coordinate system; ​ x e = r e sinθ2 where (x e ,y e ) are coordinates of the cutting edge curve of the le blade in a Cartesian coordinate system.

8. A double shear cutting tool and its edge design and optimization method according to claim 7, characterized in that, ​ 9.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is characterized in that: ​ 10. A computer readable storage medium having stored thereon a computer program, characterized in that: ​

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