Design method of a new type of triangular thread comb

Abstract

The present invention discloses a novel design method for a triangular thread comber, comprising the following steps: S101, the structural parameters of each coarse tooth of the triangular thread comber to be designed are the same, and then the key parameter for chip removal interference control, namely the ideal chip flow angle, is calculated. S102, a neural network prediction model for the chip flow angle of the single-edge bevel cutting process is obtained. S103, based on the aforementioned ideal chip flow angle and the neural network prediction model for the chip flow angle of the single-edge bevel cutting process, a model for regulating the chip removal interference of the coarse teeth in the process of turning triangular threads is established. S104, the optimal parameter solution of the chip removal interference control model of the coarse teeth of the thread comber in the process of turning triangular threads is solved, and the optimal parameters are converted into the structural parameters of the entire triangular thread comber. This method can better solve the substantial increase in cutting force and related derivative problems caused by chip removal interference, thereby improving the comprehensive performance of the tool. The adopted design concept can also be applied to the structural optimization design of other types of tools such as taps and cutting knives.

Description

Technical Field

[0001] The invention relates to the field of cutting tools, in particular to a design method for a novel triangular thread combing tool. Background Art

[0002] A triangular thread comb is a general-purpose tool for producing triangular external threads on bar stock or round tubes. Using a triangular thread comb to produce external threads achieves higher precision than using a profile rolling tool and higher efficiency than using a traditional single-tooth thread turning tool. Currently, the standard triangular thread comb, widely used in manufacturing, features the following structural characteristics: 1) the rake face of each tooth is flat; 2) the primary and secondary cutting edges of each tooth are symmetrical, with both cutting edges having an inclination angle of 0°. The widespread use of the standard triangular thread comb is due to its many advantages, the most significant of which is its simple machining method and low mass production cost. However, the standard triangular thread comb also has significant drawbacks. During the triangular thread turning process, the chips generated by the simultaneous cutting of both cutting edges on each tooth of the comb produce significant interference, which hinders chip evacuation and significantly increases cutting forces. This increased cutting force, coupled with high cutting temperatures and tool wear, results in poor overall cutting performance.

[0003] To address the aforementioned issues with current standard triangular thread comb cutters during thread turning, researchers have proposed methods to optimize the structural parameters of triangular thread comb cutters with the goal of improving tool cutting performance, achieving promising results in practice. A typical approach involves incorporating textured tool technology and tool self-lubrication into the structural optimization design of thread comb cutters. By adding microtexture to the rake face of the cutter teeth and embedding solid lubricants within the microtexture, the friction area between the tool and chip contact surface and the tool-chip friction coefficient are reduced, thereby lowering thread turning forces, cutting temperatures, and tool wear, thereby improving tool durability. Unfortunately, the techniques for adding microtexture to the rake face of the comb cutter teeth and embedding solid lubricants are complex, requiring advanced laser processing equipment and fiber laser micromachining technology. These processes are costly and currently unsuitable for mass production. More importantly, these methods simply reduce cutting forces by minimizing tool-chip friction, but fail to address the root cause of excessive cutting forces and other issues: chip interference. A comprehensive analysis reveals that widely used triangular thread comb cutter structural design schemes are few and complex to implement. Summary of the Invention

[0004] The present invention aims to overcome the aforementioned technical deficiencies by providing a novel design method for triangular thread combs. Based on theoretical analysis, numerical simulation, and cutting test results of the natural chip evacuation vectors associated with angled cutting, this method proposes optimizing the normal rake angles and rake angles of the cutting edges on either side of each roughing tooth (hereinafter referred to as a "roughing tooth"), as well as the longitudinal spacing between adjacent tooth tips, to guide the natural chip evacuation vectors along the cutting edges of each roughing tooth of the comb. This eliminates or reduces the degree of interference between these vectors, effectively addressing the significant increase in cutting force and related issues caused by chip interference, and improving the tool's overall cutting performance.

[0005] In order to solve the above technical problems, the present invention provides a technical solution: a design method of a new triangular thread comb, comprising the following steps:

[0006] S101. The structural parameters of each coarse tooth of the proposed triangular thread comb are the same. Therefore, only one of the coarse teeth is taken as the research object, and the process of turning the thread with the coarse tooth is regarded as a linear double-edged cutting process (ignoring the radius of the tool tip arc). The general method of chip removal interference control is determined by geometric analysis, and then the key parameter of chip removal interference control, the ideal chip flow angle, is calculated. It should be noted that the rake face of each coarse tooth of the proposed triangular thread comb will no longer be a plane due to the changes in the rake angle and normal rake angle of the cutting edges on both sides of the coarse tooth. The ideal chip flow angle is the single-sided chip flow angle corresponding to the free chip removal vector of the left and right cutting edges of the coarse tooth when cutting separately (single-edged bevel cutting) and the overall chip removal vector of the coarse tooth turning thread. Since the cutting edges on both sides of each coarse tooth of the proposed triangular thread comb are symmetrical, the overall chip removal vector of each coarse tooth when turning the thread is parallel to the symmetry plane of the cutting edges on both sides. More specifically, the overall chip removal vector is parallel to the intersection line (ridge line) of the rake faces corresponding to the cutting edges on both sides, and the ideal chip flow angles corresponding to the cutting edges on both sides are equal.

[0007] S102. Obtain a neural network prediction model for the chip angle of the single-edge bevel cutting process. First, complete the numerical simulation test of the single-edge bevel cutting process (the process of coarse tooth single-sided cutting edge cutting) with the help of finite element simulation software, then use the rake angle, normal front angle, main deflection angle and radial feed of the coarse tooth single-sided cutting edge in each group of experiments as the input of the chip angle neural network prediction model, and use the chip angle obtained from the experiment as the output to train the neural network model. It should be noted that, considering that there are many situations for the tooth profile angle of the triangular thread, the main deflection angle is closely related to the tooth profile angle of the triangular thread to be machined, and it is not limited to a specific angle here; the radial feed in the single-edge bevel cutting process is intended to simulate the sequential feed of the coarse teeth in the comb tool thread turning process, and is numerically equivalent to the longitudinal spacing between the tooth tops of adjacent coarse teeth; the chip angle neural network prediction model is used as a chip angle control model in subsequent parameter optimization.

[0008] S103. Based on the aforementioned ideal chip flow angle and the neural network prediction model for the chip flow angle during single-edge bevel cutting, a model is established to control the chip removal interference of the coarse tooth during triangular thread turning. Essentially, this is to establish an optimization mathematical model, using the rake angle, normal rake angle, main deflection angle, and radial feed rate of the coarse tooth single-sided cutting edge of the triangular thread comb cutter as control parameters, the difference expression between the free chip flow angle and the ideal chip flow angle when the coarse tooth single-sided cutting edge of the triangular thread comb cutter is cut as the objective function, and the empirical value range of the control parameters and the profile accuracy requirements of triangular thread turning as constraints. It should be noted that during the optimization process, the free chip flow angle of the coarse tooth single-sided cutting edge is predicted by the chip flow angle neural network prediction model; minimizing the difference between the free chip flow angle and the ideal chip flow angle when the coarse tooth single-sided cutting edge of the triangular thread comb cutter is cut is the optimization goal.

[0009] S104. Calculate the optimal parameter solution for the chip removal interference control model during the coarse turning of triangular threads using a thread comb cutter, and convert the optimal parameters into structural parameters for the entire triangular thread comb cutter. When calculating the optimal parameters, an optimization algorithm is used to optimize the parameters. The main deflection angle is set to the following value based on the triangular thread to be machined with a tooth angle of α:

[0010]

[0011] The corresponding interval constraints are set for the rake angle, normal rake angle and radial feed according to the empirical values, and the corresponding profile accuracy constraints are set according to the thread processing accuracy requirements. The set of optimal parameter solutions is finally obtained as {λ s ,γ n ,f}. Transformed into the structural parameters of the comb cutter coarse teeth, the inclination angle of the cutting edges on both sides of each coarse tooth is λ s , the normal angle is γ n The longitudinal spacing between adjacent coarse tooth tops is f. The total radial feed for rough turning and the radial feed for fine turning are then determined based on the size of the triangular thread to be machined. The number of coarse teeth is then determined based on the longitudinal spacing f between adjacent coarse tooth tops.

[0012] Furthermore, the design method of the novel triangular thread comb cutter is a relatively universal method for guiding and removing chips, which can be used for the structural design of comb cutters for processing different triangular threads, and can also be applied to the structural optimization design of other types of tools such as taps and cutting knives.

[0013] Furthermore, the triangular thread combing cutter is manufactured according to the above steps, and the structural parameters of the coarse teeth of the triangular thread combing cutter are variable, and the specific changes depend on the size of the triangular thread to be processed and the requirements for the thread profile accuracy.

[0014] Furthermore, the triangular thread comb has several coarse teeth and only one fine tooth, and the number of the coarse teeth is determined by the total radial feed of the rough thread turning and the longitudinal spacing between the tooth tops of adjacent coarse teeth.

[0015] Furthermore, in the triangular thread comb cutter, the cutting edge structures on both sides of each coarse tooth are symmetrical.

[0016] Furthermore, the front cutting surface of the triangular thread comb cutter is not a plane, and this feature is mainly derived from the non-zero inclination angles of the cutting edges on both sides of the coarse teeth.

[0017] Furthermore, the proposed design method steps only designed the angle parameters of the cutting edges on both sides of the coarse teeth of the triangular thread comb and the longitudinal spacing of the coarse tooth tops. The structural parameters of other parts are the same as those of the corresponding parts of the standard triangular thread comb.

[0018] The advantages of the present invention over the prior art are: this method utilizes theoretical analysis, numerical simulation, and cutting test results of the natural chip removal vector of angled cutting, and proposes to guide the natural chip removal vector of the cutting edge on both sides of each roughing tooth (hereinafter referred to as "coarse tooth") of the comb cutter by optimizing the normal rake angle, rake angle, and longitudinal (the tooth arrangement direction is horizontal) spacing of the adjacent coarse tooth tops of the comb cutter, thereby eliminating or reducing the degree of interference between the chip removal vectors, and can effectively solve the significant increase in cutting force and related derivative problems caused by chip removal interference, thereby improving the comprehensive cutting performance of the tool. The design concept and design method adopted here can also be applied to the structural optimization design of other types of tools such as taps and cutters.

[0019] A new triangular thread comb cutter has been designed. This tool possesses a certain chip evacuation capability, ensuring smoother chip removal. This fundamentally resolves the chip interference issue during thread turning, reduces thread turning forces by 12%-15%, and improves the tool's overall cutting performance.

[0020] The invention only optimizes the design of the normal rake angle, rake angle of the cutting edge on both sides of each coarse tooth of the triangular thread comb cutter and the longitudinal spacing between the tooth tops of adjacent coarse teeth. The overall structure of the tool is simple and can be prepared using traditional processing equipment. It has low production cost and is relatively simple and easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic structural diagram of a triangular thread comb provided by a design method of a novel triangular thread comb.

[0022] Figure 2 The invention discloses a novel triangular thread combing cutter design method. Figure 1 Schematic diagram of the structure at point A in the middle.

[0023] Figure 3 The present invention provides a novel triangular thread combing tool design method and a flow chart of the triangular thread combing tool design method.

[0024] Figure 4 It is a geometrical schematic diagram of a design method of a novel triangular thread comb cutter of the present invention, in which the cutting edges on both sides of the coarse teeth 4 independently cut a disc workpiece.

[0025] Figure 5 It is a structural schematic diagram of one side of the main cutting edge 1 of the coarse tooth 4 according to the design method of a novel triangular thread comb cutter of the present invention.

[0026] Figure 6 It is a front view structural schematic diagram of the rake face on one side of the main cutting edge 1 of the coarse tooth 4 according to the design method of the novel triangular thread comb cutter of the present invention.

[0027] Figure 7 It is a structural schematic diagram of a chip angle neural network of a design method for a novel triangular thread comb cutter of the present invention.

[0028] Figure 8 It is a schematic diagram of hyperbolic error in a triangular thread turning process according to a design method of a novel triangular thread combing cutter of the present invention.

[0029] Figure 9 It is a cross-sectional view of the precise triangular thread surface and the motion trajectory surfaces of the blades on both sides of the coarse teeth in the axial section (XOZ plane) of the design method of a new triangular thread combing cutter of the present invention.

[0030] Figure 10 It is a schematic diagram of basic dimensions of a triangular thread comber of a final design according to a design method of a novel triangular thread comber of the present invention.

[0031] Figure 11 The present invention is a schematic diagram of the dimensions of the coarse teeth of a triangular thread comb designed according to a design method of a novel triangular thread comb. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments.

[0033] Example:

[0034] The triangular thread comb cutter designed by the design method proposed in the present invention has cutting edges on both sides of each coarse tooth having a non-zero rake angle and a normal rake angle which may be zero. Figure 1This is a schematic diagram of the triangular thread comb structure provided by an embodiment of the present invention. Figure 2 yes Figure 1 The structural diagram at A in the center shows that the number of coarse teeth was uncertain at the beginning of the design, so a simplified drawing was used, omitting the structure of several coarse teeth in the middle. Teeth 4 to (n-1) are coarse teeth, and tooth n is a fine tooth. The specific structural parameters were designed using the triangular thread comb design method proposed in this invention. The main idea of ​​this method is to treat the thread turning process of each coarse tooth of the comb as a linear double-edge cutting process (ignoring the tool tip arc radius). Then, the structural parameters are optimized to guide the chip movement on both sides of the coarse tooth, thereby reducing the degree of chip interference during thread turning. Figure 3 The present invention provides a triangular thread comb cutter design method, which includes the following steps.

[0035] S101. Select the coarse tooth 4 as the research object and calculate the ideal chip flow angle. The ideal chip flow angle is the single-sided chip flow angle corresponding to when the free chip removal vectors of the cutting edges 1 and 2 on the left and right sides of the coarse tooth are cut separately (single-edge bevel cutting) and are parallel to the overall chip removal vector of the coarse tooth turning thread. Since the cutting edges on both sides of each coarse tooth of the proposed triangular thread comb are symmetrical, the overall chip removal vector of the coarse tooth 4 when turning the thread is parallel to the intersection line (ridge line) 3 of the front cutting surface corresponding to the cutting edges on both sides, and the ideal chip flow angles corresponding to the cutting edges on both sides are equal. To calculate the specific value of the ideal chip flow angle, it is necessary to perform a geometric analysis of the cutting process performed by the cutting edges on both sides of the coarse tooth 4 separately and the structure of the coarse tooth. Figure 4 This is a geometric diagram of the cutting edges on both sides of the coarse teeth 4 according to the embodiment of the present invention cutting the disc workpiece separately. I and ψ I ′ are the ideal chip flow angles corresponding to the cutting edges on both sides. Figure 5 It is a structural schematic diagram of one side of the main cutting edge 1 of the coarse tooth 4 according to an embodiment of the present invention. Figure 6 This is a front view of the rake face of the main cutting edge 1 of the coarse tooth 4 according to an embodiment of the present invention. Figure 5 and Figure 6 Based on the analytic geometry method, the ideal chip angle is solved as follows:

[0036]

[0037] where λ s and γ n are the rake angle and normal angle of the single-sided cutting edge (1 or 2) of the coarse tooth 4, K r The main deflection angle has the following relationship with the tooth profile angle α of the triangular thread to be processed:

[0038]

[0039] S102, obtain the neural network prediction model of the chip flow angle in the single-edge bevel cutting process. The single-edge bevel cutting process is a process in which the single-sided cutting edge (1 or 2) of the coarse tooth 4 participates in the cutting. The control parameters are the edge inclination angle, normal front angle, main deflection angle and radial feed of the single-sided cutting edge (1 or 2) of the coarse tooth 4, and the state parameter is the chip flow angle. First, it is necessary to obtain the experimental data for training the neural network model, and use the combination method to establish a 4-factor 8-level orthogonal matrix L 64 Then, the corresponding orthogonal numerical simulation test of the single-edge bevel cutting process is completed and the test data is collected. Furthermore, a BP neural network with a structure of 4-7-7-7-1 is established. Figure 7 This is a structural diagram of the chip angle neural network of an embodiment of the present invention. The control parameters in the orthogonal simulation test are used as the input of the neural network, and the chip angle data obtained in the test is used as the output of the neural network. The neural network is trained to finally obtain a chip angle neural network prediction model for the single-edge bevel cutting process.

[0040] S103. On the basis of the aforementioned ideal chip flow angle and the neural network prediction model of the chip flow angle in the single-edged bevel cutting process, a model is established to regulate the chip removal interference of the coarse tooth 4 in the process of turning the triangular thread. In essence, it is to establish an optimization mathematical model, using the rake angle, normal front angle, main deflection angle and radial feed rate of the single-sided cutting edge (1 or 2) of the coarse tooth 4 as control parameters, and the difference expression between the free chip flow angle and the ideal chip flow angle when the single-sided cutting edge (1 or 2) of the coarse tooth 4 is cut as the objective function, and the empirical value range of the control parameters and the profile accuracy requirements of the triangular thread turning are used as constraints. The difference between the free chip flow angle and the ideal chip flow angle is Figure 6 The model for regulating the chip interference of the coarse tooth 4 during the triangular thread turning process is expressed as follows:

[0041] min f(X)=|ψ I -ψ λ |

[0042] sth i (X)=0,i=1,2,…p

[0043] g i (X)≤0,j=1,2,…q

[0044] Where X is a vector composed of control parameters, which can be expressed as X = (λ s , γ n ,f,K r ) T , the objective function f(X) is Δψ, ψ I is the ideal chip angle value calculated by the analytical geometry method mentioned above, ψ λis the value predicted by the chip angle neural network prediction model, h i (X) is an equality constraint, which indicates the deterministic effect of the thread profile angle on the main deflection angle in the control parameters. For the embodiment of the present invention, the thread profile angle of the triangular thread to be processed by the designed triangular thread comb is 60°. Therefore, the equality constraint is expressed as follows:

[0045] h1(X)=K r -60=0

[0046] For the inequality constraint g i (X) has two sources: one is the constraints from the empirical values ​​of the rake angle, normal angle and feed rate; the other is the constraints from the accuracy requirements of the triangular thread profile being machined. The constraints from the empirical values ​​can be expressed as follows:

[0047]

[0048] Where A, B, and C represent the empirical value ranges of the rake angle, normal rake angle, and radial feed rate of the single-sided cutting edge (1 or 2) of the coarse tooth 4, respectively. The upper right subscripts U and L represent the upper and lower limits of the intervals, respectively. In the embodiment of the present invention, the specific conditions of the intervals A, B, and C are as follows:

[0049] A=[-5,15]B=[-10,25]C=[0.1,0.25]

[0050] For the constraints from the triangular thread profile accuracy requirements, it is necessary to determine the influence of the control parameters on the profile accuracy. It should be noted that the profile error in the thread processing process mainly comes from the rake angle of the single-sided cutting edge of the coarse tooth, which is essentially a hyperbolic error. Figure 8 This is a schematic diagram of the hyperbolic error during the triangular thread turning process of an embodiment of the present invention. In order to further calculate the magnitude of the hyperbolic error, it is necessary to analyze the intersection of the precise triangular thread surface and the motion trajectory of the cutting edges (1 and 2) on both sides of the coarse tooth 4 in the axial section (XOZ plane). Figure 9 It is a cross-sectional view of the precise triangular thread surface and the motion trajectory surface of the blades on both sides of the coarse teeth in the axial section (XOZ plane) of an embodiment of the present invention. Figure 9 The shaded area on the left is the overcut, and the shaded area on the right is the undercut. Analysis shows that the finish turning process performed on the final fine tooth n (hereinafter referred to as "fine tooth n") can eliminate the thread profile error caused by undercutting. However, if the coarse tooth (n-1) adjacent to fine tooth n generates a large hyperbolic error during thread turning, the overcut cross-sectional area on the left side will exceed a certain value.

[0051] Then the final finishing process of fine tooth n cannot eliminate the thread profile error caused by overcutting, and will also lead to the production of irreparable scrap. Therefore, in this thread profile accuracy analysis process, only the left overcut error caused by the coarse tooth (n-1) adjacent to the fine tooth n during the thread turning process is considered. The maximum hyperbolic error Δ is used to define the left overcut error. Δ represents the maximum distance between the point on the motion trajectory surface of the blades (1 and 2) on both sides of the coarse tooth 4 and the precise triangular thread surface AB. By analyzing the thread surface and the blade motion trajectory surface through parametric equations, the parametric equations of the left part of the truncation curve of the two spatial surfaces on the axial section (XOZ plane) can be determined as follows:

[0052]

[0053] In the above formula, G xoz Indicates the left part of the truncation curve of the precise triangular thread surface on the axial section, H xoz The truncation curve represents the motion trajectory of the cutting edge 1 on the left side of the coarse tooth 4 on the axial section, where p is the lead of the triangular thread, and d′1 is the diameter corresponding to the bottom corner of the original triangle of the thread. Its value has the following relationship with the nominal diameter of the triangular thread:

[0054] d′1=d-1.5p

[0055] t is an intermediate parameter, θ is an intermediate parameter representing an angle, θ is a function of t, and its calculation expression is as follows:

[0056]

[0057] Analyze the truncation curve of the motion trajectory of the left cutting edge 1 of the coarse tooth 4 on the axial section. According to its parametric equation, the equation of the straight line l1 tangent to the truncation curve and parallel to the truncation curve AB can be determined as follows:

[0058]

[0059] The parameter θ0 can be calculated according to the calculation expression of θ above. The parameter t0 required for calculation satisfies the following relationship:

[0060]

[0061] We can also see that the equation of AB is as follows,

[0062]

[0063] It can be understood that the maximum hyperbolic error on the left is the distance between the two parallel lines l1 and AB, and its expression is as follows:

[0064]

[0065] It should be noted that all the above expressions are obtained when the triangular thread to be processed is a standard thread and the tooth angle is 60°, where Figure 9 In the figure, l2 and l3 are partial truncation curves of the precise triangular thread surface in the axial section, corresponding to the target machining profile of the final fine-turning thread of the triangular thread comb fine tooth n. To ensure high thread profile accuracy and avoid the generation of irreparable scrap, it is obvious that the error of the reserved machining allowance before the final fine-turning cannot be too large. That is, the rough tooth (n-1) adjacent to the fine tooth n cannot produce too much overcut error when rough-turning the triangular thread. If the maximum allowable error is [ε], the thread profile accuracy constraint condition is as follows:

[0066] g4(X)=Δ-η[ε]≤0

[0067] It should be noted that η is defined as the thread profile accuracy assurance coefficient, which ranges from 0 to 1, and the value of [ε] depends on the radial feed rate f of the final finishing process. n , which can be expressed as follows,

[0068]

[0069] In the embodiment of the present invention, the radial feed amount f of the final finishing is set to n is 0.09mm (i.e. the longitudinal spacing between the tops of the fine teeth n and the coarse teeth (n-1) is 0.09mm), and the thread profile accuracy assurance coefficient η is 0.1. The triangular thread to be processed is M56×2, so the diameter corresponding to the bottom corner point of the original triangle is,

[0070] d′1=56-1.5×2=53mm

[0071] S104. Solve the optimal parameter solution of the chip removal interference control model in the triangular thread turning process through the particle swarm algorithm. The particle swarm size is set to 500, the maximum number of iterations is 5000, the individual and social learning factors are both 0.4, the inertia factor is 0.4, and the maximum flight speed is 0.3. Finally, the optimal structural parameters of the triangular thread comb proposed in the embodiment of the present invention are obtained. More specifically, the optimized triangular thread comb has a coarse tooth single-sided cutting edge (symmetrical structure) with an inclination angle of 10°, a normal rake angle of 0°, and a longitudinal spacing between adjacent coarse tooth tops of 0.21 mm. According to the code M56×2 of the triangular pattern to be processed, the total radial feed rate can be determined as,

[0072] f=0.5413p=1,0826mm

[0073] The total radial feed of rough turning is:

[0074] f 4～(n-1) =ff n =0.9926mm

[0075] Combined with the aforementioned 0.21mm longitudinal spacing f between the tops of adjacent coarse teeth, we can determine that the number of coarse teeth is 5. In summary, the overall structure of the triangular thread comb cutter in the embodiment of the present invention is: 5 coarse teeth and 1 fine tooth; the longitudinal spacing between the tops of adjacent coarse teeth is 0.21mm, and the longitudinal spacing between the tops of the fine teeth and adjacent coarse teeth is 0.09mm. Figure 10 This is a schematic diagram of the basic dimensions of the final designed triangular thread comb provided by an embodiment of the present invention. Figure 11 It is a schematic diagram of the dimensions of the coarse teeth of the triangular thread comb designed in an embodiment of the present invention.

[0076] The triangular thread comb cutter of the above embodiment can reduce the cutting force by 12%-15% when turning threads, and the chips are discharged smoothly, and the tool durability is also improved.

[0077] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A new design method for a triangular thread comb, characterized in that The following steps are involved: S101. The structural parameters of each coarse tooth of the proposed triangular thread comb are the same. Therefore, only one of the coarse teeth is taken as the research object. The process of turning the thread with the coarse tooth is regarded as a linear double-edge cutting process. The radius of the tool tip arc is ignored. The general method of chip removal interference control is determined through geometric analysis. Then the key parameters of chip removal interference control are calculated, which is the ideal chip flow angle. The front cutting face of each coarse tooth of the proposed triangular thread comb is no longer a plane due to the changes in the rake angle and normal rake angle of the cutting edges on both sides. The ideal chip flow angle is the single-sided chip flow angle corresponding to the free chip removal vectors of the left and right cutting edges of the coarse tooth when cutting separately and are parallel to the overall chip removal vector of the coarse tooth turning thread. Since the cutting edges on both sides of each coarse tooth of the proposed triangular thread comb are symmetrical, the overall chip removal vector of each coarse tooth when turning the thread is parallel to the symmetry plane of the cutting edges on both sides. The overall chip removal vector is parallel to the intersection line of the rake faces corresponding to the cutting edges on both sides, and the ideal chip flow angles corresponding to the cutting edges on both sides are equal in size. The cutting process of the left and right cutting edges of the coarse tooth is a single-edge bevel cutting process. S102. Obtain a neural network prediction model for the chip angle of a single-edge bevel cutting process. First, numerical simulation tests of the single-edge bevel cutting process are completed using finite element simulation software. Then, the rake angle, normal rake angle, main deflection angle, and radial feed rate of the coarse tooth single-sided cutting edge in each set of tests are used as inputs to the neural network prediction model for the chip angle. The chip angle obtained from the tests is used as output to train the neural network model. Considering that there are various tooth profile angles of triangular threads, the main deflection angle is closely related to the tooth profile angle of the triangular thread to be machined. The main deflection angle is not restricted to a specific angle here. The radial feed rate in the single-edge bevel cutting process is intended to simulate the sequential feed rate of the coarse teeth in the comb cutter thread turning process, and is numerically equivalent to the longitudinal spacing between the tooth tops of adjacent coarse teeth. The neural network prediction model for the chip angle is used as a chip angle control model in subsequent parameter optimization. S103. Based on the aforementioned ideal chip flow angle and the neural network prediction model for the chip flow angle during single-edge bevel cutting, a model is established to control the chip removal interference of the coarse tooth during triangular thread turning. The rake angle, normal rake angle, principal deflection angle, and radial feed rate of the coarse tooth single-sided cutting edge of the triangular thread comb cutter are used as control parameters. The difference expression between the free chip flow angle and the ideal chip flow angle during cutting by the coarse tooth single-sided cutting edge of the triangular thread comb cutter is used as the objective function. The empirical value range of the control parameters and the profile accuracy requirements for triangular thread turning are used as constraints. The free chip flow angle during cutting by the coarse tooth single-sided cutting edge is predicted by the neural network prediction model for the chip flow angle. Minimizing the difference between the free chip flow angle and the ideal chip flow angle during cutting by the coarse tooth single-sided cutting edge of the triangular thread comb cutter is the optimization goal. S104, solving the optimal parameter solution of the chip removal interference control model in the process of coarse-tooth turning a triangular thread with a thread comb cutter, and converting the optimal parameter solution into the structural parameters of the entire triangular thread comb cutter. When solving the optimal parameter solution, an optimization algorithm is used to optimize the parameters. According to the triangular thread to be processed with a tooth angle of α, the above-mentioned main deflection angle is set to the following determined value: The corresponding interval constraints of the cutting edge inclination angle, normal rake angle and radial feed are set according to the empirical values. At the same time, the corresponding profile accuracy constraints are set according to the thread processing accuracy requirements. Finally, the set of optimal parameter solutions is obtained as {λ s ,γ n ,f}, converted into the structural parameters of the comb cutter coarse teeth: the cutting edge inclination angle of each coarse tooth is λ s , the normal angle is γ n , the longitudinal spacing value of the tooth tops of adjacent coarse teeth is f, and then the total radial feed of rough turning and the radial feed of fine turning are determined according to the size of the triangular thread to be processed, and the number of coarse teeth is determined in combination with the longitudinal spacing value f of the tooth tops of adjacent coarse teeth.

2. The design method of a novel triangular thread comb according to claim 1, characterized in that: The design method of the novel triangular thread comb cutter is a relatively universal method for guiding and removing chips, which can be used for the structural design of comb cutters for processing different triangular threads, and can also be applied to the structural optimization design of taps and cutter cutters.

3. A triangular thread comb, characterized in that: The triangular thread combing knife According to the steps in claim 1, the structural parameters of the coarse teeth of the triangular thread comb are variable, and the specific changes depend on the size of the triangular thread to be processed and the requirements for the thread profile accuracy.

4. A triangular thread comb according to claim 3, characterized in that: The triangular thread comb has several coarse teeth and only one fine tooth. The number of the coarse teeth is determined by the total radial feed of the rough thread turning and the longitudinal spacing between the tooth tops of adjacent coarse teeth.

5. The triangular thread comb according to claim 3, characterized in that: The triangular thread comb cutter has symmetrical cutting edge structures on both sides of each coarse tooth.

6. The triangular thread comb according to claim 3, characterized in that: The front cutting surface of the triangular thread comb cutter is not a plane, and this feature is mainly derived from the non-zero inclination angles of the cutting edges on both sides of the coarse teeth.

7. The triangular thread comb according to claim 3, characterized in that: The steps in claim 1 only design the angle parameters of the cutting edges on both sides of the coarse teeth of the triangular thread comb and the longitudinal spacing values ​​of the tooth tops of adjacent coarse teeth. The structural parameters of other parts are the same as those of the corresponding parts of the standard triangular thread comb.

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