CN115338463A - Taper ball end mill and chip dividing groove design method thereof - Google Patents

Abstract

The invention discloses a taper ball end mill and a chip dividing groove design method thereof, wherein the taper ball end mill comprises a bottom edge, a peripheral edge and a handle part; the peripheral edge comprises a chip groove, a first rear cutter face, a second rear cutter face and a chip dividing groove; the intersection of the chip flute and the first rear cutter face forms a cutting edge; the chip dividing groove is arranged between the first rear cutter face and the second rear cutter face; the axial symmetry line of the chip dividing groove is perpendicular to the direction of the central line of the cutter, the width of the chip dividing groove is continuously increased from the first rear cutter face to the second rear cutter face along the axial symmetry line of the chip dividing groove, the depth of the chip dividing groove in a plane perpendicular to the first rear cutter face is constant, the optimal size and tolerance of the chip dividing groove are determined by adopting an orthogonal analysis method and a single-factor analysis method, the width of the chip dividing groove is continuously increased from the cutting edge along the direction perpendicular to the cutting edge, and the phenomenon that the rear end of the chip dividing groove interferes with the front end to cause cutter vibration is avoided.

Description

Design method of a tapered ball end mill and its chip splitter

technical field

The invention relates to the technical field of end mills, in particular to a tapered ball end mill and a design method for chip splitting grooves thereof.

Background technique

Tapered ball nose end mills are widely used in the machining of key components such as impellers, blisks and casings in the aerospace industry. With the country's great investment in the aerospace industry, the market demand for tapered ball end mills has grown rapidly in the same industry. For parts that require large depth of cut, a chip splitter is designed on the tapered ball end mill to reduce cutting force and enhance chip removal. However, for difficult-to-machine materials such as titanium alloys, high-temperature alloys, and high-strength steels, conventional tapered ball-end mills with chip dividers have the following problems:

1. Since the tapered ball head is widely used in surface profiling milling, and due to the taper, the diameter of the tool from the bottom edge along the axial direction continues to increase. The design of the conventional chip splitter will cause the rear end of the chip splitter to interfere with the front end. risk, causing the tool to vibrate and reducing the surface quality of the workpiece;

2. Conventional taper ball nose end mills are designed to reduce the cutting force and enhance the chip removal ability. The shape design directly affects the heat dissipation conditions and tool strength of the tool. At present, there is still a lack of tool function-oriented chip divider design method .

Contents of the invention

The main purpose of the present invention is to propose a kind of taper ball end mill and the design method of chip distribution groove thereof, it has overcome the weak point existing in the design method of the taper ball end mill chip distribution groove of prior art, On the one hand, the width of the chip splitter of the tapered ball-nose end mill is set to increase continuously from the cutting edge along the vertical direction of the cutting edge, so as to avoid the rear end of the chip splitter interfering with the front end and causing tool vibration; on the other hand, the orthogonal analysis method is adopted Obtain the best match of the structural parameters of the chip splitter; based on the best matching result of the structural parameters of the chip splitter, use the single factor analysis method to obtain the tolerance of the structural parameters of the chip splitter, so that the performance of the chip splitter on the tool can be improved more significantly and the ball can be improved. head end mill productivity.

The present invention adopts following technical scheme:

On the one hand, a kind of taper ball nose end mill, comprises bottom cutting edge, peripheral cutting edge and shank; Said peripheral cutting edge comprises flute, first relief surface, second relief surface and chip splitting groove; Said containment The intersection of the chip flute and the first flank constitutes a cutting edge; the chip splitter is arranged between the first flank and the second flank; the axis of symmetry of the chip splitter is vertical In the direction of the center line of the tool, the width of the chip splitting flute increases continuously from the first flank to the second flank along the axial symmetry line of the chip splitting flute, and is perpendicular to the first flank In the plane of , the depth in the groove of the chip splitter remains unchanged.

Preferably, the chip splitting groove adopts the following design method:

Orthogonal analysis method and finite element simulation method are used to obtain the best matching of the structural parameters of the chip splitter;

Based on the best matching results of the structural parameters of the chip splitter, the tolerance of the structural parameters of the chip splitter is obtained by single factor analysis and finite element simulation.

Preferably, orthogonal analysis and finite element simulation are used to obtain the best matching of structural parameters of the chip splitter, specifically including:

According to the number of structural parameters of the chip splitter and the relationship between the parameters, the test plan is determined by using an orthogonal design table;

Using the finite element simulation method, the part with the smallest core diameter/blade diameter of a complete chip splitter is intercepted as the simulation model, and the milling simulation is carried out according to the determined test plan, and the cutting edge stress is used as the judgment standard;

According to the range analysis of the orthogonal test, the degree of influence of the structural parameters of the chip splitter on the stress of the cutting edge is determined, the most significant influencing structural parameters are found, and the best matching result of the structural parameters of the chip splitter is obtained according to the structural parameter-stress curve.

Preferably, the structural parameters of the chip splitter include: front width W _min , rear width W _max , length L and depth H, and the rear width W _max is greater than the front width W _min .

Preferably, the orthogonal analysis method adopts a four-factor three-level orthogonal design table, and the four factors include the front width W _min , the rear width W _max , the length L and the depth H.

Preferably, the ranges of front-end width W _min , rear-end width W _max , length L and depth H are as follows: _{0.05mm≤Wmin≤0.2mm} , _{0.1mm≤Wmax≤0.5mm} ; 0.03D≤L≤0.2D, D Indicates the diameter of the bottom edge of the tapered ball end mill; 0.2mm ≤ H ≤ 1mm.

Preferably, based on the best matching result of the structural parameters of the chip splitting flute, the tolerance of the structural parameters of the chip splitting flute is obtained by single factor analysis and finite element simulation method, including:

Based on the best matching results of the structural parameters of the chip splitter, the single factor analysis method is used to set three of the parameters as fixed values, and the other parameter is divided into five values, and the finite element simulation is carried out to verify the parameter stress change;

Based on the maximum value of the cutting edge stress which is the median of the five values of the parameter, determine the acceptable stress variation range, and finally take the parameter value within the stress variation range as the tolerance of the parameter.

On the other hand, a method for designing a chip splitter of a tapered ball-nose end mill includes:

Orthogonal analysis method and finite element simulation method are used to obtain the best matching of the structural parameters of the chip splitter;

Based on the best matching results of the structural parameters of the chip splitter, the tolerance of the structural parameters of the chip splitter is obtained by single factor analysis and finite element simulation.

Preferably, orthogonal analysis and finite element simulation are used to obtain the best matching of structural parameters of the chip splitter, specifically including:

According to the number of structural parameters of the chip splitter and the relationship between the parameters, the test plan is determined by using an orthogonal design table;

Using the finite element simulation method, the part with the smallest core diameter/blade diameter of a complete chip splitter is intercepted as the simulation model, and the milling simulation is carried out according to the determined test plan, and the cutting edge stress is used as the judgment standard;

According to the range analysis of the orthogonal test, the degree of influence of the structural parameters of the chip splitter on the stress of the cutting edge is determined, the most significant influencing structural parameters are found, and the best matching result of the structural parameters of the chip splitter is obtained according to the structural parameter-stress curve.

Preferably, based on the best matching result of the structural parameters of the chip splitting flute, the tolerance of the structural parameters of the chip splitting flute is obtained by single factor analysis and finite element simulation method, including:

Based on the best matching results of the structural parameters of the chip splitter, the single factor analysis method is used to set three of the parameters as fixed values, and the other parameter is divided into five values, and the finite element simulation is carried out to verify the parameter stress change;

Based on the maximum value of the cutting edge stress which is the median of the five values of the parameter, determine the acceptable stress variation range, and finally take the parameter value within the stress variation range as the tolerance of the parameter.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) The width of the chip splitter of the tapered ball end mill of the present invention increases continuously from the cutting edge along the direction vertical to the cutting edge, avoiding the interference of the chip splitter rear end with the front end, causing tool vibration;

(2) The design of the chip splitting flute of the present invention takes the tool strength as the judgment standard, adopts the orthogonal analysis method, and utilizes simulation analysis to obtain the best matching parameters of the front end width, rear end width, length and depth of the chip splitting flute, so that The chip splitter improves the performance of the tool more significantly;

(3) The design of the chip splitting flute of the present invention takes the tool strength as the judgment standard, adopts the single factor analysis method, and utilizes simulation analysis to obtain the processing tolerance range of the front end width, rear end width, length and depth of the chip splitting flute respectively. While ensuring the stable performance of the ball end mill tool, there will be no excess precision, so as to improve the production efficiency of the ball end mill and reduce the cost.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy Understand, enumerate the specific embodiment of the present invention below.

According to the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will be more aware of the above and other objects, advantages and features of the present invention.

Description of drawings

Fig. 1 is the structural representation of the taper ball end mill of the embodiment of the present invention;

Fig. 2 is a schematic structural view of a peripheral edge of a tapered ball end mill according to an embodiment of the present invention;

Fig. 3 is a schematic structural view of the flank and the chip splitting groove of the tapered ball nose end mill according to the embodiment of the present invention;

Fig. 4 is a schematic diagram of the structure of the common cutting surface of the chip splitter according to the embodiment of the present invention;

Fig. 5 is a schematic diagram of the first flank projection of the chip splitter according to the embodiment of the present invention;

Fig. 6 is a schematic cross-sectional view of C-C of the chip splitter of the embodiment of the present invention;

Fig. 7 is a flow chart of the design method of the chip dividing groove of the tapered ball end mill according to the embodiment of the present invention;

Fig. 8 is a schematic diagram of the blade diameter and core diameter of the tapered ball end mill according to the embodiment of the present invention;

Fig. 9 is a simulation schematic diagram of a tapered ball end mill according to an embodiment of the present invention;

Fig. 10 is a schematic diagram of cutting stress simulation of a tapered ball end mill according to an embodiment of the present invention;

Fig. 11 is a graph showing the relationship between the front width W _min of the chip splitter and the stress change in the embodiment of the present invention;

Fig. 12 is a graph showing the relationship between the width W _max of the rear end of the chip splitting flute and the stress change according to the embodiment of the present invention;

Fig. 13 is a graph showing the relationship between the length L of the chip splitting flute and the stress change in the embodiment of the present invention;

Fig. 14 is a graph showing the relationship between the depth H of the chip splitter and the stress change in the embodiment of the present invention;

Fig. 15 is a curve diagram of the maximum stress variation of the cutting edge according to the embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only part of the embodiments of the present invention, not all embodiments, based on The embodiments of the present invention and all other embodiments obtained by persons of ordinary skill in the art without making creative efforts all belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the term "comprising", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also other elements not expressly listed, or elements inherent in the process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Referring to Figures 1 to 4, a tapered ball end mill includes a bottom edge 1, a peripheral edge 2 and a shank 3; the peripheral edge 2 includes a chip pocket 4, a first relief surface 5, a second Two flanks 6 and a chip splitter 8; the intersection of the chip flute 4 and the first flank 5 constitutes a cutting edge 7; the chip splitter 8 is arranged on the first flank 5 and the second flank 6; the axis of symmetry of the chip splitting flute 8 is perpendicular to the direction of the tool centerline, and the width of the chip splitting flute 8 is along the axis of symmetry of the chip splitting flute 8, starting from the first rear The direction from the cutter face 5 to the second flank 6 increases continuously, and in the plane perpendicular to the first flank 5 , the inner depth of the chip splitter 8 remains unchanged.

Specifically, as shown in Figure 2, the structural parameters of the chip splitter 8 are based on the projection of the common tangent plane of the first flank 5 of the front and rear two sections of the chip splitter 8, and the axial symmetry line of the chip splitter 8 is perpendicular to the tool centerline A-A. When the cutting edge 7 is worn during the machining process, the width of the front end of the chip splitter 8 will become larger. If the conventional chip splitter 8 is designed with a fixed slot width, the rear end of the chip splitter 8 may interfere with the machining allowance. Generates vibrations, reduces tool life, and degrades machined surface quality.

Therefore, the width of the chip splitting groove 8 adopts a variable width design, which has an automatic compensation function. Referring to Fig. 5 and Fig. 6, the width W of the chip splitter 8 increases continuously from the cutting edge along the axial symmetry line B-B of the chip splitter 8 from the first flank 5 to the second flank 6, so that the front end width Wmin, the width of the rear end is Wmax, and the length of the chip splitter 8 is L. In the plane perpendicular to the first flank 5, the depth of the chip splitting flute 8 is H, and the depth in the flute is constant. Wherein, F1 is the projected width of the first flank 5, and F2 is the projected width of the second flank 6.

As shown in Figure 7, further, in order to improve the performance of the tool by the chip splitter more significantly, and ensure the stability of the tool performance of the ball end mill, improve the production efficiency of the ball end mill and reduce the cost, the chip splitter The groove adopts the following design method:

S701, using the orthogonal analysis method and the finite element simulation method to obtain the best matching of the structural parameters of the chip splitter;

S702. Based on the optimal matching result of the structural parameters of the chip splitter, the tolerance of the structural parameters of the chip splitter is obtained by using the single factor analysis method and the finite element simulation method.

Specifically, use orthogonal analysis and finite element simulation to obtain the optimal match of the structural parameters of the chip splitter, including:

According to the number of structural parameters of the chip splitter and the relationship between the parameters, the test plan is determined by using an orthogonal design table;

Using the finite element simulation method, the part with the smallest core diameter/blade diameter of a complete chip splitter is intercepted as the simulation model, and the milling simulation is carried out according to the determined test plan, and the cutting edge stress is used as the judgment standard;

According to the range analysis of the orthogonal test, the degree of influence of the structural parameters of the chip splitter on the stress of the cutting edge is determined, the most significant influencing structural parameters are found, and the best matching result of the structural parameters of the chip splitter is obtained according to the structural parameter-stress curve.

In this embodiment, in order to obtain the best match of the structural parameters of the chip splitter, the orthogonal analysis method is used to analyze the impact of tool parameter changes on the tool life. The structural parameters of the chip splitter described in this embodiment include four parameters of the front width W _min , the rear width W _max , the length L and the depth H, and they are independent variables. Therefore, four factors and three levels of orthogonal design tables are used.

According to the actual production demand, the ranges of the front width W _min , the rear width W _max , the length L and the depth H are set as follows:

(1) 0.05mm≤W _min ≤0.2mm, when W _min <0.05mm, the width of the chip splitter is too small, which reduces the chip breaking effect and easily causes chip blocking; when W _min >0.2mm, the width of the chip splitter is too large, Reduce the strength of the tool and make the tool easy to vibrate;

(2) 0.1mm≤W _max ≤0.5mm, when W _max <0.1mm, the width of the chip dividing groove is too small, which reduces the chip breaking effect and easily causes chip blocking; when W _max >0.5mm, the width of the chip dividing groove is too large, Reduce the strength of the tool and make the tool easy to vibrate;

(3) 0.03D≤L≤0.2D, when L<0.03D, the first flank or the second flank is easy to interfere with the machining allowance generated by the chip divider; because L will not be greater than the second flank Face width, when L>0.2D, the width of the second flank of the tool is too large, the second flank is prone to interference, and at the same time the chip pocket of the tool is reduced, and it is not easy to remove chips; see Figure 8, D is a tapered ball head Milling cutter bottom edge diameter;

(4) 0.2mm≤H≤1mm, because the depth of the chip splitter needs to be greater than the maximum feed per tooth of the tool, when H<0.2mm, the maximum feed per tooth of the tool is too small, which reduces the processing efficiency of the tool; when H>1mm , The tool strength is too low, it is easy to generate vibration, and the tool life is reduced.

Based on the above range of structural parameters, this embodiment takes cemented carbide D10 taper ball end milling cutter as an example to generate an orthogonal design table, specifically as shown in Table 1. The side milling test is simulated by finite element simulation, and the stress of the cutting edge is used as the criterion. The smaller the stress, the higher the tool strength.

Table 1 Orthogonal design table of structure parameters of chip splitter

Test number W_min W_max L h 1 0.05 0.1 0.3 0.2 2 0.05 0.3 1.15 0.6 3 0.05 0.5 2 1 4 0.125 0.1 1.15 1 5 0.125 0.3 2 0.2 6 0.125 0.5 0.3 0.6 7 0.2 0.1 2 0.6 8 0.2 0.3 0.3 1 9 0.2 0.5 1.15 0.2

Due to the taper angle α of the tapered ball-end milling cutter, the blade diameter and core diameter of the tapered ball-end milling cutter are not constant, so the core diameter/blade diameter is constantly changing. As shown in Figure 9, in order to reduce the amount of simulation calculation, the part with the smallest core diameter/blade diameter value is selected, and at the same time it has a complete chip splitter structure.

As shown in Figure 10, the simulation is carried out with this model. According to the stress change of the cutting edge, the ranking order of the significance of the structural parameters to the tool strength is obtained, and the best matching scheme of the structural parameters of the chip breaker is obtained according to the stress value of the tool.

The parameters and stress curves are shown in Fig. 11, Fig. 12, Fig. 13 and Fig. 14 respectively.

It can be seen from Fig. 11 to Fig. 14 that W _max has the most significant influence on tool stress, which is the most important structural parameter for chip splitter design. The tool stress increases gradually with the increase of W _max , but W _max ≥ W _min , and W _min greater than 0.125mm has little effect on the tool stress. At the same time, the tool stress also gradually increases with the increase of L. When H=0.6mm, the tool stress Minimal stress. Therefore, the best parameters of chip splitting groove of cemented carbide D10 taper ball end milling cutter are W _min = 0.125mm, W _max = 0.3mm, L = 0.3mm, H = 0.6mm.

Further, based on the best matching result of the structural parameters of the chip flute, the tolerance of the structural parameters of the chip flute is obtained by using the single factor analysis method and the finite element simulation method, including:

Based on the best matching results of the structural parameters of the chip splitter, the single factor analysis method is used to set three of the parameters as fixed values, and the other parameter is divided into five values, and the finite element simulation is carried out to verify the parameter stress change;

Based on the maximum value of the cutting edge stress which is the median of the five values of the parameter, determine the acceptable stress variation range, and finally take the parameter value within the stress variation range as the tolerance of the parameter.

According to the best matching result of the parameters of the chip splitting groove of the cemented carbide D10 taper ball end milling cutter, in order to obtain the parameter tolerances of the front width W _min , the rear end width W _max , the length L and the depth H, a single factor analysis method is adopted, among which Three parameters are set to fixed values, and the other parameter is divided into five values equally, and the finite element simulation is carried out to verify the change of parameter stress. Based on the maximum value of the median cutting edge stress of the parameter value, the acceptable stress variation range is determined, and finally the parameter value within the stress variation range is used as the tolerance of the parameter.

Specifically, this embodiment takes W _max as an example. According to the above analysis, W _max should not be less than 0.125 mm, and the stress on the cutting edge of the tool increases significantly after W _max >0.3 mm, so the parameter values are selected as shown in Table 2.

Table 2 W _max tolerance single factor test parameter values

When W _max =0.25mm, the tool cutting edge stress value ±0.2% is taken as the tolerance value range. The maximum stress change of the cutting edge of the test simulation tool is shown in Fig. 15.

It can be seen from Fig. 15 that when W _max <0.15mm, the stress value will not be less than 210MPa, and when W _max >0.3mm, the stress value will be greater than 210.84MPa, therefore, the value of W _max is 0.13mm-0.3mm.

In this embodiment, the rear end width W _max is taken as an example to determine the acceptable stress variation range, and finally the parameter value within the stress variation range is used as the tolerance of the rear end width W _max . For other structural parameters, the front width W _min , length L and depth H can be obtained by using the above-mentioned single factor analysis method and finite element simulation method to obtain corresponding tolerances, which will not be described in this embodiment.

The design of the chip splitter of the present invention takes the tool strength as the judgment standard, adopts the orthogonal analysis method, and utilizes simulation analysis to obtain the best matching parameters of the front end width, rear end width, length and depth of the chip splitter, so that the chip splitter The performance improvement of the tool is more significant; further, the single factor analysis method and simulation analysis are used to obtain the processing tolerance range of the front width, rear end width, length and depth of the chip splitter respectively. While the performance is stable, there will be no excess precision, so as to improve the production efficiency of the ball end mill and reduce the cost.

Referring to Fig. 7, according to another aspect of the present invention, a method for designing a chip splitting groove of a tapered ball-nose end mill includes:

S701, adopting the orthogonal analysis method and the finite element simulation method to obtain the best matching of the structural parameters of the chip splitter;

S702. Based on the optimal matching result of the structural parameters of the chip splitting flute, the tolerance of the structural parameters of the chip splitting flute is obtained by using a single factor analysis method and a finite element simulation method.

Specifically, use orthogonal analysis and finite element simulation to obtain the optimal match of the structural parameters of the chip splitter, including:

According to the number of structural parameters of the chip splitter and the relationship between the parameters, the test plan is determined by using an orthogonal design table;

Using the finite element simulation method, the part with the smallest core diameter/blade diameter value of a complete chip splitter is intercepted as a simulation model, and the milling simulation is carried out according to the determined test plan, and the cutting edge stress is used as the judgment standard;

According to the range analysis of the orthogonal test, the degree of influence of the structural parameters of the chip splitter on the stress of the cutting edge is determined, the most significant influencing structural parameters are found, and the best matching result of the structural parameters of the chip splitter is obtained according to the structural parameter-stress curve.

Specifically, based on the best matching result of the structural parameters of the chip splitter, the tolerance of the structural parameters of the chip splitter is obtained by using the single factor analysis method and the finite element simulation method, including:

Based on the best matching results of the structural parameters of the chip splitter, the single factor analysis method is used to set three of the parameters as fixed values, and the other parameter is divided into five values, and the finite element simulation is carried out to verify the parameter stress change;

Based on the maximum value of the cutting edge stress which is the median of the five values of the parameter, determine the acceptable stress variation range, and finally take the parameter value within the stress variation range as the tolerance of the parameter.

For the specific implementation process of the design method of the chip splitting groove of a tapered ball-nose end mill, refer to the description of a tapered ball-nose end mill, which will not be repeated in this embodiment.

The above description is only a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical scheme of the present invention and its improved concept to make equivalent replacements or changes, should be covered within the scope of protection of the present invention.

Claims (10)

1. A kind of taper ball end milling cutter, comprises bottom cutting edge, peripheral cutting edge and shank; Said peripheral cutting edge comprises flute, the first flank, the second flank and chip dividing flute; Said chip flute The intersection of the groove and the first flank constitutes a cutting edge; it is characterized in that the chip splitter is arranged between the first flank and the second flank; the axis of the chip splitter The line of symmetry is perpendicular to the direction of the centerline of the tool, and the width of the chip splitting flute is along the axis of symmetry of the chip splitting flute, increasing continuously from the first flank to the second flank, and perpendicular to the first In the plane of the flank, the inner depth of the chip splitter remains constant. 2. The tapered ball-nose end mill according to claim 1, wherein the chip divider adopts the following design method: Orthogonal analysis method and finite element simulation method are used to obtain the best matching of the structural parameters of the chip splitter; Based on the best matching results of the structural parameters of the chip splitter, the tolerance of the structural parameters of the chip splitter is obtained by single factor analysis and finite element simulation. 3. The tapered ball-nose end mill according to claim 2, characterized in that the optimal matching of the structural parameters of the chip splitter is obtained by using the orthogonal analysis method and the finite element simulation method, specifically comprising: According to the number of structural parameters of the chip splitter and the relationship between the parameters, the test plan is determined by using an orthogonal design table; Using the finite element simulation method, the part with the smallest core diameter/blade diameter of a complete chip splitter is intercepted as the simulation model, and the milling simulation is carried out according to the determined test plan, and the cutting edge stress is used as the judgment benchmark; According to the range analysis of the orthogonal test, the degree of influence of the structural parameters of the chip splitter on the stress of the cutting edge is determined, the most significant influencing structural parameters are found, and the best matching result of the structural parameters of the chip splitter is obtained according to the structural parameter-stress curve. 4. The tapered ball end mill according to claim 2, characterized in that, the structural parameters of the chip divider include: front end width W _min , rear end width W _max , length L and depth H, the rear end The width W _max is larger than the front end width W _min . 5. The chip splitter of a tapered ball-nose end mill according to claim 4, wherein the orthogonal analysis method adopts a four-factor three-level orthogonal design table, and the four factors include the front width W _min , the rear end width W _max , length L and depth H. 6. The tapered ball end mill according to claim 4, characterized in that the ranges of the front end width W _min , rear end width W _max , length L and depth H are as follows: _{0.05mm≤Wmin≤0.2mm} , 0.1 mm≤W _max ≤0.5mm; 0.03D≤L≤0.2D, D represents the diameter of the bottom edge of the tapered ball end mill; 0.2mm≤H≤1mm. 7. The tapered ball nose end mill according to claim 4, characterized in that, based on the optimal matching result of the structural parameters of the chip splitting flute, the tolerance of the structural parameters of the chip splitting flute is obtained by single factor analysis and finite element simulation method ,include: Based on the best matching result of the structural parameters of the chip splitter, the single factor analysis method is used to set three of the parameters as fixed values, and the other parameter is divided into five values, and the finite element simulation is carried out to verify the parameter stress change; Based on the maximum value of the cutting edge stress which is the median of the five values of the parameter, the acceptable stress variation range is determined, and finally the parameter value within the stress variation range is used as the tolerance of the parameter. 8. A method for designing chip-separating grooves of tapered ball-nose end mills, characterized in that it comprises: Orthogonal analysis method and finite element simulation method are used to obtain the best matching of the structural parameters of the chip splitter; Based on the best matching results of the structural parameters of the chip splitter, the tolerance of the structural parameters of the chip splitter is obtained by single factor analysis and finite element simulation. 9. The design method of the chip-separating groove of the tapered ball-nose end mill according to claim 8, characterized in that, adopting the orthogonal analysis method and the finite element simulation method to obtain the best matching of the structural parameters of the chip-separating groove, specifically comprising: According to the number of structural parameters of the chip splitter and the relationship between the parameters, the test plan is determined by using an orthogonal design table; Using the finite element simulation method, the part with the smallest core diameter/blade diameter of a complete chip splitter is intercepted as the simulation model, and the milling simulation is carried out according to the determined test plan, and the cutting edge stress is used as the judgment standard; According to the range analysis of the orthogonal test, the degree of influence of the structural parameters of the chip splitter on the stress of the cutting edge is determined, the most significant influencing structural parameters are found, and the best matching result of the structural parameters of the chip splitter is obtained according to the structural parameter-stress curve. 10. The design method of the chip-separating flute of the tapered ball-nose end mill according to claim 8, characterized in that, based on the optimal matching result of the structural parameters of the chip-separating flute, the single factor analysis method and the finite element simulation method are used to obtain the points. Tolerances for flute configuration parameters, including: Based on the best matching result of the structural parameters of the chip splitter, the single factor analysis method is used to set three of the parameters as fixed values, and the other parameter is divided into five values, and the finite element simulation is carried out to verify the parameter stress change; Based on the maximum value of the cutting edge stress which is the median of the five values of the parameter, the acceptable stress variation range is determined, and finally the parameter value within the stress variation range is used as the tolerance of the parameter.

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