An optimization design method for a performance-oriented broach with concave functional structure

Abstract

The present invention discloses an optimization design method for a concave functional structure broach oriented to performance; the method is as follows: First, obtain the shear force during the cutting process. Second, obtain the friction coefficient of the broach to be optimized. Third, optimize the parameters of the measured broach. The present invention aims at a broach with a concave functional structure, realizes the accurate calculation of the shear force and the friction coefficient during the cutting process, realizes the correlation between the geometric dimensions of the concave functional structure and the broach cutting parameters, and realizes the evaluation and optimization of the cutting performance of the concave functional structure tool. By introducing the macroscopic geometric dimensions of the concave functional structure, the present invention realizes the optimization and improvement of the cutting performance of the tool by regulating the geometric dimensions of the functional structure. According to the obtained shear force F<subgt;s< / subgt> and friction coefficient u<subgt;1< / subgt> of the broach with a concave functional structure, the present invention adjusts the functional structure dimensions of the broach, improving the performance of the broach.

Description

Technical Field

[0001] The present invention relates to the technical field of broach performance optimization design, and in particular to an optimization design method for an internally concave functional structure broach oriented to performance. Technical Background

[0002] In order to improve the cutting performance of broaches, many scholars have used texture technology, coating technology or additive technology to optimize broaches. However, all these methods will seriously affect the internal stress of broaches, resulting in a significant reduction in the service life of broaches, making broach optimization "treating the symptoms rather than the root cause". Therefore, fundamentally exploring the methods for broach performance evaluation and optimization and exploring the new machining mechanism brought by the broach geometric structure have become effective breakthrough points.

[0003] Currently, for example, the patent with the application number CN201610529271.5 discloses a micro-milling force modeling method based on the wear effect of broaches. This method comprehensively considers factors such as the trochoidal motion trajectory of the tooth tip of the broach tooth, the radial runout of the tooth tip, and the elastic recovery of the machined surface, and obtains a micro-milling force prediction model not based on broach wear. However, the working environment of this method has great limitations, and the prediction accuracy is difficult to verify. It is only suitable for micro-parts milling, and it is difficult to reflect the cutting performance of broaches in conventional broaching. Another example is the patent with the application number CN202011533751.1, which discloses a cutting force modeling method for chamfered edge tools. The cutting force modeling method for chamfered edge tools provided by this invention can calculate the cutting force of chamfered edge tools. However, in the calculation process of this method, only the basic geometric parameters and cutting parameters of the chamfered edge tool are considered, and the parameters of other microstructures are not taken into account. Therefore, the error of this method is large and it does not have universality.

[0004] The modeling of functional structures has always attracted the attention of the academic community of cutting processing. Therefore, solving the problem of functional structure cutting performance modeling has important research significance for guiding and optimizing the cutting performance of broaches. The modeling of broach cutting performance is not only a solution to a class of problems, but also provides strong theoretical guidance for the field of advanced manufacturing technology. When evaluating the cutting performance of functional structure broaches, due to the influence of factors such as the shape, size, depth and quantity of the functional structure on the front tool face of the broach, many research scholars often cannot evaluate it in the form of establishing a mathematical model when studying broaches with "functional structures". As a result, it is difficult for scholars to consider the cutting performance of a broach from a theoretical level. Summary of the Invention

[0005] The object of the present invention is to provide an optimized design method for a concave functional structure broach oriented to performance aiming at the above problems. This method constructs a mathematical model of the cutting performance of the functional structure in view of the influence of factors such as the shape, size and quantity of the functional structure on the rake face of the broach, and combines with the parameters of the geometric dimensions of the traditional broach, so as to accurately predict the cutting performance of the broach; it is a method for establishing a mathematical model of the cutting performance of the initial broach by considering the basic parameters of the traditional broach; it is a method for preparing a functional structure on the rake face of the broach based on the traditional broach model, and constructing a mathematical model of the cutting performance of the concave functional structure broach according to the geometric dimensions of various functional structures; it is a method for accurately predicting the performance of the broach based on the various indexes of the cutting performance mathematical model and solving the difficult problem of performance modeling calculation under multi-factor coupling; it is a method for evaluating the effect of the microscopic physical machining mechanism by introducing the macroscopic geometric parameters of the functional structure; it is a method that combines the traditional broach mathematical model, the functional structure broach mathematical model and the performance evaluation system.

[0006] An optimized design method for a concave functional structure broach oriented to performance, and the object of optimization is a broach with a functional structure arranged on the rake face. The functional structure includes a plurality of groove units arranged in sequence along the cutting edge direction.

[0007] This parameter optimization method includes the following steps:

[0008] Step 1: Obtain the shear force F during the cutting process s .

[0009] 1-1. The expression of the actual contact area Ac between the broach and the chip is as follows:

[0010] Ac = l·(d - ny1) + l w ·n·y1

[0011] where l is the length of the tool-chip contact on the plane where the tested rake face is located; l w is the contact length between the part of the tool-chip aligned with the groove unit and the rake face; d is the chip width; y1 is the width of the groove unit; n is the number of groove units aligned with the chip.

[0012] 1-2. The expression of the shear force F s of the broach to be optimized during the cutting process is as follows:

[0013]

[0014] where τ s is the shear stress of the broach to be optimized, is the shear angle between the tool and the chip; β is the friction angle of the tool-chip contact surface; γ is the rake angle of the broach.

[0015] Step 2. Obtain the friction coefficient μ1 of the broach to be optimized. The expression of the friction coefficient μ1 of the broach to be optimized is as follows:

[0016]

[0017] where F C is the cutting force.

[0018] Step 3. Optimize the parameters of the broach under test.

[0019] If F s > 180 N and μ1 > 0.6, then use several of the following schemes for parameter adjustment:

[0020] Scheme ①. Adjust the rake angle γ of the broach to be optimized to 80% - 90% of the original value;

[0021] Scheme ②. Reduce the width y1 of the groove unit on the broach to be optimized and the spacing z1 between two adjacent groove units. The value ranges of y1 and z1 are 1 μm - 200 μm.

[0022] If 120 N < F s < 180 N or 0.5 < μ1 < 0.6, and the broach to be optimized is used to machine a workpiece with a hardness less than or equal to 160 HBW, then use several of the following two schemes for parameter adjustment:

[0023] Scheme ①. Increase the width y1 of the groove unit on the broach to be optimized; the increase range is 3% - 5% of the original value.

[0024] Scheme ②. Increase the width z1 of the groove unit on the broach to be optimized; the increase range is 10% - 20% of the original value.

[0025] If 120 N < F s < 180 N or 0.5 < μ1 < 0.6, and the broach to be optimized is used to machine a workpiece with a hardness greater than 160 HBW, then use several of the following two schemes for parameter adjustment:

[0026] Scheme ①. Reduce the width y1 of the groove unit on the broach to be optimized; the reduction range is 5% - 7% of the original value.

[0027] Scheme ②. Reduce the width z1 of the groove unit on the broach to be optimized; the reduction range is 10% - 20% of the original value.

[0028] Except for the above three cases in this step, the cutting performance of the broach to be optimized meets the requirements, and no parameter adjustment is required.[[ID=�8]]

[0029] After the parameters of the broach to be optimized are adjusted, re - execute Steps 1 and 2.

[0030] Preferably, the contact length l w is determined as follows:

[0031] When the contact range between the chip and the rake face of the broach does not exceed the end of the groove unit away from the cutting edge, the expression of the contact length l w is as follows:

[0032] l w = s1

[0033] where s1 is the distance between the groove unit and the cutting edge.

[0034] When the contact range between the chip and the rake face of the broach exceeds the end of the groove unit away from the cutting edge, the expression of the contact length l w is as follows:

[0035] l w = l - x1

[0036] where x1 is the length of the groove unit.

[0037] Preferably, when F s > 180 N and u1 > 0.6, adjust the shear angle of the optimized broach so that the angle between the rake face of the optimized broach and the machined vertical plane is less than the preset threshold ratio of the rake angle γ; the threshold ratio is 30% - 50%.

[0038] Preferably, when F s > 180 N and u1 > 0.6, replace the material of the optimized broach, and the hardness of the optimized broach increases.

[0039] Preferably, the optimized broach uses orthogonal broaching when broaching the workpiece.

[0040] Preferably, the groove unit is rectangular, with a length of 0.7 mm - 1 mm, a width of 0.03 mm - 0.08 mm, and a distance between adjacent two groove units of 0.1 mm - 0.2 mm.

[0041] Preferably, the optimized broach is a single-tooth broach.

[0042] Preferably, the optimized broach is provided with a functional structure, a positioning hole, and a cutting edge. The rake angle γ of the optimized broach is 10° - 15°; the clearance angle α of the optimized broach 1 is 5° - 8°. The diameter of the positioning hole is 3.5 mm - 4.5 mm; the effective length of the cutting edge is 0.2 mm - 0.6 mm.

[0043] Preferably, a limiting structure is provided on one side of the bottom of the optimized broach near the cutting edge. The limiting structure is in the shape of an inward concave wedge.

[0044] The beneficial effects of the present invention are as follows:

[0045] 1. For the broach with an inner concave functional structure, the present invention realizes the accurate calculation of the shear force F s and the friction coefficient u1 during the cutting process, realizes the correlation between the geometric dimensions of the inner concave functional structure and the cutting parameters of the broach, and realizes the evaluation and optimization of the cutting performance of the inner concave functional structure tool.

[0046] 2. By introducing the macroscopic geometric dimensions of the inner concave functional structure, the present invention realizes the optimization and improvement of the cutting performance of the tool by regulating the geometric dimensions of the functional structure.

[0047] 3. According to the obtained shear force F s and the friction coefficient u1 of the broach with an inner concave functional structure, the dimensions of the functional structure of the broach are adjusted, improving the performance of the broach.

[0048] Description of the Drawings

[0049] Figure 1 is a schematic structural diagram of the optimized broach in the present invention;

[0050] Figure 2 is a side view of the optimized broach in the present invention;

[0051] Figure 3 is a partial top view of the optimized broach in the present invention;

[0052] Figure 4 is a cutting mechanism diagram of the optimized broach in the present invention. Detailed Embodiment

[0053] The present invention will be further described below with reference to the drawings.

[0054] A performance-oriented optimization design method for a broach with an inner concave functional structure is used to obtain the shear force F s and the friction coefficient u during the cutting process of the optimized broach 1, and accurately evaluate and predict the cutting performance of the broach, providing theoretical guidance for correcting and optimizing the relevant geometric parameters of the broach. The optimized broach 1 is specifically a single-tooth broach with an inner concave functional structure on the rake face of the tooth.

[0055] Such as Figures 1-3As shown, the optimized broach 1 is provided with a functional structure 1-1, a positioning hole 1-2, a cutting edge 1-3 and a limiting structure 1-4. The rake angle γ of the optimized broach 1 is 10° to 15°, and its initial value in this embodiment is 12°; the clearance angle α of the optimized broach 1 is 5° to 8°, and its initial value in this embodiment is 7°. The diameter of the positioning hole 1-2 is 3.5 mm to 4.5 mm, and its initial value in this embodiment is 4 mm; the effective length of the cutting edge 1-3 is 0.2 mm to 0.6 mm, and its initial value in this embodiment is 0.25 mm;

[0056] As Figure 1 and Figure 3 shown, the limiting structure 1-4 is arranged on one side of the bottom of the optimized broach 1 close to the cutting edge, and is in the shape of an inward concave wedge, so as to facilitate the installation of the optimized broach 1 on the tool holder of the traditional integral broach and share part of the broaching force. The functional structure broach 1-1 includes

[0057] The functional structure 1-1 is composed of a plurality of groove units arranged in sequence along the cutting edge direction. The length x1 of the groove unit is 0.7 mm to 1 mm, the width y1 is 0.03 mm to 0.08 mm, and the distance z1 between two adjacent groove units is 0.1 mm to 0.2 mm; the initial value of x1 in this embodiment is 0.8 mm, the initial value of y1 is 0.05 mm, and the initial value of the distance z1 is 0.15 mm.

[0058] The parameter optimization method of the inward concave functional structure broach includes the following steps:

[0059] Step 1: Although the cutting process of metal is a three-dimensional process, in order to more intuitively explain the balance force system on the cutting shear plane of the functional broach, the present invention establishes a two-dimensional cutting shear plane mechanical relationship model of the broach based on the traditional metal cutting theory, as Figure 4 shown.

[0060] Step 2: For the current signal acquisition technology, the cutting force (F C ) and the normal pressure (Ft) can be collected by a three-component dynamometer. Therefore, F C and Ft become the breakthrough points for calculating other cutting parameters. According to the relationship between the forces during the machining process, other cutting parameters are correlated with F C and Ft, and the following can be obtained:

[0061]

[0062]

[0063] Among them, F z is the resultant force of the normal pressure (Ft) and the cutting force (F C ); Fs is the shear force; is the shear angle between the tool and the chip; β is the friction angle of the tool-chip contact surface; γ is the rake angle of the broach.

[0064] Step 3. The shear angle is an important variable in the cutting process. During low-speed cutting, the relationship between the shear angle and the speed is significant. For high-speed cutting, the relationship between the shear angle and the cutting speed can be ignored. Therefore, through research, the calculation formula for the shear angle is obtained as follows:

[0065]

[0066] where C1 is the shear force correction coefficient of the broach, and C2 is the friction angle correction coefficient of the broach.

[0067] Step 4. Based on the above formula, the shear force of the broach can be obtained. Since the higher the strength limit of the metal material, the greater the shear resistance, the lower the plasticity, the smaller the relative cutting depth corresponding to shearing, and the higher the requirements and performance for the broach. Therefore, in metal broaching, the optimization of the broach can be achieved by adjusting the material of the broach, the rake angle and the shear angle of the broach according to the value of the shear force. It can be concluded that when two of the factors of the metal material, the rake angle or the shear angle of the broach are fixed, the performance of the broach can be optimized by adjusting the size of the other parameter. However, this simple optimization method cannot meet the requirements of the changing working conditions in actual processing.

[0068] Step 5. Since the curling and wear of the chip during the cutting process will directly affect the surface quality of the machined surface of the workpiece, the research on the relationship between the broach and the chip is of great significance. Combining the relationship between the component forces, we can get:

[0069] F f = F r ×sin(β) Equation (4)

[0070] where F r is the resultant force at the tool-chip interface; F f is the frictional force at the tool-chip interface.

[0071] Step 6. Since the chip moves at a constant speed when the cutting state is stable, the resultant force F z at the broach-workpiece interface and the resultant force F r at the broach-chip interface are a pair of balanced forces. According to the principle of force balance, we can get:

[0072] F r = F z Equation (5)

[0073] Step 7: According to the established 2D model and the chip force balance principle, combined with equations (1), (4), and (5), the basic geometric relationships between various parameters can be obtained:

[0074]

[0075] Although this method can calculate the friction force between the broach and the chip, the error of the result obtained by this method is very large and it is not referenceable. This is because when calculating with this formula, the changes in the geometric structure of the broach are not considered.

[0076] Step 8: As shown in Figure 3 , when establishing a cutting performance model for the concave functional structure, the first thing to consider is that the area of the rake face of the broach has changed greatly, which will directly affect the contact area between the broach and the chip. Therefore, the change in the area of the rake face has become the breakthrough point for functional structure modeling; accordingly, the friction force F f is expressed as:

[0077] F f = Ac × τ s Equation (7)

[0078] In the formula, A c is the actual contact area between the broach and the chip, and τ s is the shear stress of the broach to be optimized.

[0079] Step 9: Since the groove-shaped and round-hole-shaped structures are the most widely used and effective methods in the preparation of functional structures, the present invention takes the groove-shaped structure as the modeling object. According to the broach with a functional structure having a groove geometry, the tool-chip contact area A c can be written as:

[0080] Ac = l·(d - ny1) + l w ·n·y1 Equation (8)

[0081] In the formula, l is the length of the tool-chip fitting on the plane where the tested rake face is located; l w is the contact length between the part of the tool-chip aligned with the groove unit and the rake face; d is the chip width (when the chip is in a stable state, the change range of the chip width is small and can be ignored); y1 is the width of the groove unit; n is the number of groove units aligned with the chip.

[0082] Step 10: Construct an expression for the contact length l w .

[0083] When the contact range between the chip and the rake face of the broach does not exceed the end of the groove unit away from the cutting edge, the expression for the contact length l w is shown in Equation (9):

[0084] l w = s1 Equation (9)

[0085] Where s1 is the distance between the groove unit and the cutting edge.

[0086] When the contact range between the chip and the rake face of the broach exceeds the end of the groove unit away from the cutting edge, the contact length l w is expressed as shown in Equation (10):

[0087] l w = l - x1 Equation (10)

[0088] Where x1 is the length of the groove unit;

[0089] Step Eleven: Combining Equations (7) and (8), the frictional force F f is expressed as shown in Equation (11).

[0090] F f = Ac × τ s = (l·(d - ny1) + l w ·n·y1)τ s Equation (11)

[0091] Step Twelve: The friction coefficient has always been the most frequently mentioned parameter in broach optimization. It can intuitively evaluate the wear of the broach during cutting and the quality of the machined sample surface. To find a precise and effective calculation method, it is best to relate them to the cutting force and the shape of the functional structure.

[0092] According to the calculation principle of the friction coefficient, it can be obtained that:

[0093]

[0094] Where F n is the normal pressure on the tool-chip contact surface.

[0095] Step Fifteen: From the mechanical relationship model of the two-dimensional cutting shear plane of the broach, the relationship between F n and F C can be obtained:

[0096]

[0097] Step Sixteen: The friction coefficient u1 of the broach to be optimized is constructed as shown in Equation (14):

[0098]

[0099] Step Eighteen: Relate F r to the shear force F s along the shear plane to obtain the shear force F sThe expression is as shown in Equation (15).

[0100]

[0101] It can be seen from this that any change in the groove unit will seriously affect the shear force and friction coefficient during the cutting process, thereby affecting the cutting performance of the broach.

[0102] Step Nineteen: Evaluate the performance of the broach to be measured according to the obtained friction coefficient u1 and shear force F s When the friction coefficient u1 and shear force F s are larger, the wear of the broach is greater, the cutting performance of the broach is poorer, the quality of the machined surface of the workpiece is lower, and the service life of the broach is shorter.

[0103] According to the formula obtained above, the method for evaluating and optimizing the performance of the broach is as follows:

[0104] When 60N < F s < 120N or 0.2 < u1 < 0.5, it is considered that the cutting performance of the concave functional structure meets the requirements;

[0105] When F s > 180N or u1 > 0.6, at this time, the values of the shear force F s and the friction coefficient u1 will both exceed the shear force F s and the friction coefficient u1 of the conventional broach during broaching, indicating that there are relatively large problems with the parameters of the broach body, resulting in poor cutting performance of the broach. Therefore, it is necessary to adjust the parameters of the tool by a large margin. The adjustment schemes are as follows:

[0106] 1) Adjust the rake angle γ of the broach to 80% - 90% of the original value;

[0107] 2) Adjust the cutting angle of the broach, that is, the angle between the front tool face of the tool and the vertical plane to be machined is less than 30% - 50% of the value of the rake angle γ;

[0108] 3) The parameters of the concave unit on the front tool face of the tool are set too large, and the parameters should be adjusted to 1um < y1 < 200um; 1um < Z1 < 200um, preferably y1 = 100um; Z1 = 100um

[0109] When the hardness of the material to be machined is lower than 160HBW, and 120N < F s < 180N or 0.5 < u1 < 0.6, at this time, the values of the shear force F s and the friction coefficient u1 are both lower than the values obtained by broaching the conventional broach, indicating that the concave functional structure on the front tool face of the broach has a certain improvement in the cutting performance of the broach. In order to maximize the cutting performance of the concave functional structure, the following optimizations can be taken:[[]]END]]

[0110] 1) First, adjust the width y1 of the groove unit on the rake face of the broach. Since the strength of viscous materials (such as aluminum alloy, titanium alloy, etc.) is relatively low, material migration is likely to occur during the cutting process. Therefore, the width y1 of the groove unit can be relatively large, and preferably, the adjustment range is 3% - 5% of the original value of y1.

[0111] 2) During the actual cutting process, the wear of the broach is mainly affected by the area of the tool-chip contact surface. After the width y1 of the groove unit on the rake face of the broach adopts the optimized scheme, further optimization can be achieved by adjusting the spacing Z1 of the groove unit. For the cutting of viscous materials, the chip is easily adhered to the rake face, resulting in serious built-up edges, which makes the machining quality of the workpiece poor. Therefore, the value of the spacing Z1 of the groove unit can be adjusted to 110% - 120% of the original value.

[0112] When the hardness of the material to be machined is greater than 160 HBW, and 120 N < F s < 180 N or 0.5 < u1 < 0.6, the values of the shear force F s and the friction coefficient u1 are relatively large, and the cutting performance of the internal concave functional structure broach is poor. The following optimizations can be taken:

[0113] 1) First, adjust the width y1 of the groove unit on the rake face of the broach. Since the material with a hardness greater than 160 HBW to be machined is a relatively hard material, the tool-chip contact area during the machining process is relatively small. Therefore, the width y1 of the groove unit can be relatively small, and preferably, the adjustment range is 5% - 7% of the original value of y1.

[0114] 2) For the cutting of relatively hard materials, the cutting difficulty is relatively large, and the chip is easily broken. Therefore, the value of the spacing Z1 of the groove unit can be adjusted to 80% - 90% of the original value.

[0115] This mathematical model is not only effective for the grooved texture broach, but also effective for the pit-type, cross-scale micro-texture, and composite micro-texture broaches with regular arrangements of textures.

[0116] When orthogonal cutting is adopted, the rake angle of the broach is zero, which can effectively reduce the calculation process. Therefore, it is recommended to adopt the orthogonal cutting method as much as possible when optimizing the broach.

Claims

1. A performance-oriented optimization design method for the broach of concave functional structure, characterized in that: The rake face of the optimized broach is provided with a functional structure (1-1); the functional structure (1-1) includes a plurality of groove units arranged in sequence along the cutting edge direction; The optimization method includes the following steps: Step 1, obtain the shear force F during the cutting process s ; 1-1. The expression of the actual contact area Ac between the broach and the chip is as follows: Ac = l·(d - ny1) + l w ·n·y1 Among them, l is the length of the tool-chip contact on the plane where the tested rake face is located; l w is the contact length between the part of the chip-alignment groove unit and the rake face; d is the chip width; y1 is the width of the groove unit; n is the number of groove units for chip alignment; 1-2. Shearing force F of the optimized broach during cutting s The expression is as follows: where τ s is the shear stress of the broach to be optimized, is the shear angle between the tool and the chip; β is the friction angle of the tool-chip contact surface; γ is the rake angle of the broach; Step 2. Obtain the friction coefficient u1 of the optimized broach; the expression of the friction coefficient u1 of the optimized broach is as follows: Among them, F C is the cutting force; Step 3. Optimize the parameters of the broach to be measured; (1) If F s > 180 N and u1 > 0.6, then adjust the parameters using several of the following schemes: Option ①. Adjust the rake angle γ of the optimized broach to 80% - 90% of the original value; Option ②. Reduce the width y1 of the groove units on the optimized broach and the spacing z1 between two adjacent groove units; the value ranges of y1 and z1 are 1μm - 200μm; (2) If 120N < F s <180N or 0.5 < u1 < 0.6, and the optimized broach is used to machine a workpiece with a hardness less than or equal to 160 HBW, then several of the following two schemes are used for parameter adjustment: Option ①. Increase the width y1 of the groove units on the optimized broach; the increase range is 3% - 5% of the original value; Option ②. Increase the width z1 of the groove units on the optimized broach; the increase range is 10% - 20% of the original value; (3) If 120N < F s < 180N or 0.5 < u1 < 0.6, and the optimized broach is used to machine a workpiece with a hardness greater than 160 HBW, then several of the following two schemes are used for parameter adjustment: Option ①. Reduce the width y1 of the groove units on the optimized broach; the reduction range is 5% - 7% of the original value; Option ②. Reduce the width z1 of the groove units on the optimized broach; the reduction range is 10% - 20% of the original value; Except for the above three cases in this step, if the cutting performance of the optimized broach meets the requirements, no parameter adjustment is required; After the parameters of the optimized broach are adjusted, re-execute Steps 1 and 2.

2. The optimized design method of a performance-oriented concave functional structure broach according to claim 1, characterized in that: Contact length l w is obtained as follows: When the contact range between the chip and the rake face of the broach does not exceed the end of the groove unit away from the cutting edge, the expression for the contact length l w is as follows: l w ＝s1 Wherein, s1 is the spacing between the groove unit and the cutting edge; When the contact range between the chip and the rake face of the broach exceeds the end of the groove unit away from the cutting edge, the expression of the contact length l w is as follows: l w ＝l-x1 Wherein, x1 is the length of the groove unit.

3. A method for optimizing the design of a performance-oriented internal concave functional structure broach according to claim 1, characterized in that: At F s When > 180 N and u1 > 0.6, adjust the shear angle of the optimized broach such that the angle between the rake face of the optimized broach and the machined vertical surface is less than the preset threshold ratio of the rake angle γ; The threshold ratio is 30% - 50%.

4. A performance-oriented optimization design method for a concave functional structure broach according to claim 1, characterized in that: At F s When > 180 N and μ1 > 0.6, replace the material of the optimized broach, and the hardness of the optimized broach increases.

5. A method for optimizing the design of a performance-oriented concave functional structure broach according to claim 1, characterized in that: The optimized broach uses orthogonal broaching when broaching the workpiece.

6. The optimized design method of a performance-oriented internal concave functional structure broach according to claim 1, characterized in that: The groove units are rectangular, with a length of 0.7mm - 1mm, a width of 0.03mm - 0.08mm, and the spacing between two adjacent groove units is 0.1mm - 0.2mm.

7. A method for optimizing the design of a performance-oriented concave functional structure broach according to claim 1, characterized in that: The optimized broach is a single-tooth broach.

8. A performance-oriented optimization design method for a concave functional structure broach according to claim 7, characterized in that: The optimized broach (1) is provided with a functional structure (1-1), a positioning hole (1-2) and a cutting edge (1-3); the rake angle γ of the optimized broach (1) is 10° - 15°; the clearance angle α of the optimized broach 1 is 5° - 8°; the diameter of the positioning hole (1-2) is 3.5mm - 4.5mm; the effective length of the cutting edge (1-3) is 0.2mm - 0.6mm.

9. A method for optimizing the design of a performance-oriented concave functional structure broach according to claim 7, characterized in that: A limiting structure (1-4) is arranged on one side of the bottom of the optimized broach (1) close to the edge; the limiting structure (1-4) is in the shape of an inward concave wedge.

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