Design method of single crystal diamond ball-end multi-blade micro-milling cutter

Abstract

The application relates to a design method of a single-crystal diamond ball-head multi-blade micro-milling cutter, and relates to the technical field of single-crystal diamond cutter manufacturing. According to the number of blades, a single-crystal diamond typical crystal face with symmetrical frequency multiplication is selected, and the single-crystal diamond ball radius and the blade rake angle are determined; the single-crystal diamond ball is ground and prepared and polished; a ball head model of a to-be-processed multi-blade micro-milling cutter is established, and parameter design is carried out with the aid of axial and radial section planes; a phase angle of a grinding direction vector and an initial crystal direction is obtained by adopting a folding symmetry method, dynamic micro tensile strength distribution of any grinding direction on the surface of the single-crystal diamond ball is obtained by extension, and the blades are obtained according to the results by selecting positions with equal intervals and consistent values as blade opening positions. Through optimization of the removal size and the blade opening position of the single-crystal diamond required for forming the blades, the adverse effects of mechanical property anisotropy of the single-crystal diamond on the preparation and cutting performance of the micro-milling cutter can be weakened, and the blade angle and the parameters can be independently and flexibly designed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of single crystal diamond cutter manufacturing, and particularly relates to a design method of a single crystal diamond ball-head multi-blade micro-milling cutter. BACKGROUND

[0002] With the continuous progress of science and technology, the micro-electro-mechanical system manufacturing technology, bioengineering, optical engineering and other fields have put forward higher requirements for the level of ultra-precision machining, especially in the field of ultra-precision machining of complex optical molds of high-hardness difficult-to-machine materials (such as WC). Micro-milling has flexible machining adaptability and can realize ultra-smooth machining of micro-complex structures. However, the traditional single-blade single crystal diamond micro-milling cutter has low durability and milling efficiency, and it is difficult to meet the current industrial demand. Therefore, it is urgent to develop a single crystal diamond multi-blade micro-milling cutter manufacturing technology.

[0003] Due to the serious anisotropy of the mechanical and physical properties of single crystal diamond, the grinding and machining performance of different crystal faces and directions is very different, the symmetry of the cutting edge of the multi-blade micro-milling cutter is poor, which affects the surface quality and the number of cutting edges participating in milling. Therefore, the design and structure of the single crystal diamond ball-head multi-blade micro-milling cutter is crucial to its cutting performance. Based on the above analysis, it can be seen that the single crystal diamond multi-blade micro-milling cutter is not a simple scaling of the conventional milling cutter. On the one hand, due to the increase of the ratio of cutter diameter to cutting thickness, the load per unit volume of the micro-milling cutter is generally tens of times that of the conventional milling cutter. The same tool features (such as spiral grooves) not only cannot normally play a role, but also reduce the overall stiffness of the single crystal diamond micro-milling cutter, which may cause the micro-milling cutter to bend and break. On the other hand, after scaling, the processing difficulty of some structural features of the conventional milling cutter increases sharply, which may be limited by the manufacturing technology and lead to excessive or unprocessable. Therefore, reasonable parameter design is extremely important for the manufacturing of single crystal diamond multi-blade micro-milling cutter.

[0004] In addition, artificial PCD polycrystalline diamond is currently widely used as a tool material for micro-milling cutter, and the blade shape is mostly a simple geometric polygon. PCD diamond is mainly made of diamond particles and binder sintered under high pressure. Due to the randomness of the shape and distribution of the abrasive particles, it is impossible to make a micro-milling cutter with extremely high sharpness. Compared with the isotropic PCD polycrystalline diamond with binder, natural single crystal diamond has higher hardness and can be made into extremely sharp cutting edges. For example, through reasonable selection of crystal faces and directions, a balance between wear resistance and sharpness can be achieved. However, natural single crystal diamond has extremely high hardness and strong anisotropy, and reasonable parameter design and planning of grinding crystal direction are required for the preparation of the cutter. Therefore, the research on the design method of single crystal diamond micro-milling cutter not only can improve the preparation level of micro-milling cutter, but also plays an important role in the development of ultra-precision machining technology. SUMMARY

[0005] In order to solve the problems in the background art, the application provides a design method of a single-crystal diamond ball-head multi-blade micro-milling cutter, which optimizes the removal size and blade opening position of the single-crystal diamond required for forming the blade, helps to weaken the adverse effects of the mechanical property anisotropy of the single-crystal diamond on the preparation and cutting performance of the micro-milling cutter, and ensures the independent and flexible design of the blade angle and parameters.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme: a design method of a single-crystal diamond ball-head multi-blade micro-milling cutter, comprising the following steps:

[0007] Step one: according to the number of blades required by the multi-blade micro-milling cutter to be machined, a single-crystal diamond typical crystal face with a corresponding symmetrical frequency is selected, and the radius of the single-crystal diamond ball of the multi-blade micro-milling cutter to be machined and the blade rake angle are determined according to the mechanical properties and processing characteristics of the target machining material of the cutter;

[0008] Step two: the grinding preparation and polishing of the single-crystal diamond ball are completed according to the determined radius;

[0009] Step three: a ball head model of the multi-blade micro-milling cutter to be machined is established for analysis, and parameter design is performed by means of axial and radial cross sections, respectively, and the blades with different rake angles are obtained through parameter design, a radial cross section plane coordinate system of the ball head model is established with the center of the circle as the origin, the horizontal direction as the x-axis and the vertical direction as the y-axis, wherein when the depth direction side wall of the processing groove is in the second quadrant and the first quadrant of the radial cross section plane coordinate system of the ball head model, the blade rake angle is in a positive rake angle state and a negative rake angle state, respectively;

[0010] Step four: according to the different area conditions of the grinding direction vector on the surface of the single-crystal diamond ball, the phase angle ω of the grinding direction vector and the initial crystal direction is obtained by using the folding symmetry method, and the dynamic micro tensile strength distribution of the single-crystal diamond ball surface in any grinding direction is further obtained according to the symmetrical frequency of the single-crystal diamond by combining the calculation formula of the dynamic micro tensile strength of the arbitrary crystal face crystal direction of the diamond crystal;

[0011] Step five: according to the dynamic micro tensile strength distribution result of the single-crystal diamond, positions with equal intervals and consistent values are selected as the blade opening positions, the processing grooves are formed by removing the diamond material at the blade opening positions, and a plurality of consistent blades are obtained.

[0012] Further, the parameter design of step three is as follows:

[0013] The radius of the single crystal diamond ball is R, the vertical distance between the depth direction side wall of the processed groove and the y axis of the radial section plane coordinate system of the ball head model is s1, the vertical distance between the width direction side wall of the processed groove and the x axis of the radial section plane coordinate system of the ball head model is s2, the axial section plane coordinate system of the ball head model is established with the center of the circle as the origin, the horizontal direction is the x axis, the vertical direction is the y axis, the angle between the processed groove and the x axis of the axial section plane coordinate system of the ball head model is the use inclination angle ψ;

[0014] To make the rake angle of the blade consistent with the design in actual use, s1 should satisfy:

[0015]

[0016] In the formula, α1 is the rake angle of the blade formed by the depth direction side wall of the processed groove and the surface of the single crystal diamond ball, r is the radius of the radial section plane, and the relationship between r and the radius R of the single crystal diamond ball is represented as:

[0017] r=Rsinψ (2)

[0018] The use inclination angle ψ is selected according to the dynamic microscopic tensile strength distribution of the single crystal diamond ball;

[0019] When the rake angle of the blade is in the negative rake angle state, it should satisfy:

[0020]

[0021] In the formula, n is the number of blades, α2 is the rake angle of the blade formed by the width direction side wall of the processed groove and the surface of the single crystal diamond ball, and is represented as:

[0022]

[0023] The relationship between the vertical distance s2 and the cutting depth d of the processed groove is represented as:

[0024] d=rcosα1-s2 (5)

[0025] When the rake angle of the blade is in the positive rake angle state, it should satisfy:

[0026]

[0027] According to the formula (1) to the formula (6), by giving the single crystal diamond ball radius R, the blade rake angle α1 and the use inclination angle ψ of the multi-blade micro-milling cutter to be processed, the depth and width of the processed groove can be determined.

[0028] Further, the dynamic microscopic tensile strength distribution of the step four is specifically as follows:

[0029] For any crystal face P of the single crystal diamond sphere surface, a processing groove is prepared by a grinding disc in the tangent direction thereof, a spherical coordinate system with a radius of 1 is established with the spherical center of the single crystal diamond sphere as the origin, the single crystal diamond sphere surface is equally divided into 48 unit regions by the coordinate axis symmetry planes y=±x, z=±x, z=±y, x=0, y=0 and z=0 of the spherical coordinate system, the representative region and the reference region thereof are determined according to the axial crystal direction of the single crystal diamond sphere, the direction vertically downward in any region is defined as the initial crystal direction, the grinding direction vectors of different regions other than the representative region are moved to the reference region by means of symmetry and folding, the phase angle ω of the grinding direction vector in different regions and the initial crystal direction is calculated, and the calculation formula of the dynamic micro tensile strength of the crystal direction of any crystal face of the diamond crystal is represented as follows:

[0030]

[0031] In the formula, σ tdp is the dynamic micro tensile strength of the crystal direction of any crystal face, η1 is the weight value of the {100} crystal face group affecting any crystal face P, η2 is the weight value of the {110} crystal face group affecting any crystal face P, η3 is the weight value of the {111} crystal face group affecting any crystal face P, ω is the phase angle generated by any crystal face P, and ω0 is a phase angle correction coefficient.

[0032] η1, η2 and η3 are represented as follows:

[0033]

[0034] ω0 is represented as follows:

[0035]

[0036] In the formula, m and n are the coordinate values of the normal vector (1, n, m) of any crystal face P in the spherical coordinate system.

[0037] Further, in step five, before the diamond material is removed at the split blade position, the top of the single crystal diamond sphere is removed, and the removal amount is not more than the midpoint in the length direction of the processing groove.

[0038] Compared with the prior art, the beneficial effects of the present application are:

[0039] 1. The method of the present application considers the fine size, weak rigidity of the micro milling cutter and the high hardness of the single crystal diamond, and establishes a quantitative design method of tool characteristic parameters based on the requirements of the grinding process and the basic characteristics of the ball head multi-blade micro milling cutter, so that high-efficiency machining of different mechanical performance materials can be realized by changing the angle of the blade, and the application range of the tool and the design method is increased.

[0040] 2、The method of the present application obtains the dynamic micro tensile strength distribution of the surface grinding of the single crystal diamond ball according to the anisotropy of the mechanical properties of the single crystal diamond, and provides guidance and theoretical basis for the selection of the blade preparation position, and can obtain multiple blades with consistent cutting performance and service life;

[0041] 3、The single crystal diamond ball head multi-blade micro-milling cutter designed by the method of the present application can realize extremely small thickness cutting through rotation and multi-blade cutting, which is helpful to obtain high-quality surfaces and products of difficult-to-machine materials. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic diagram of the cutting position of the section surface of the ball head model in the design method of the present application;

[0043] Figure 2 is Figure 1 a schematic diagram of the axial section surface of the ball head model in the present application;

[0044] Figure 3 is Figure 1 a schematic diagram of the radial section surface of the ball head model in the present application;

[0045] Figure 4 is a schematic diagram of the grinding direction in the design method of the present application;

[0046] Figure 5 is a schematic diagram of the spherical coordinate system of the single crystal diamond ball in the design method of the present application;

[0047] Figure 6 is a dynamic micro tensile strength distribution diagram of the surface of the single crystal diamond ball in the embodiment;

[0048] Figure 7 is a physical diagram of the single crystal diamond ball head multi-blade micro-milling cutter prepared in the embodiment. DETAILED DESCRIPTION

[0049] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] As Figures 1-5 shown, a design method of a single crystal diamond ball head multi-blade micro-milling cutter comprises the following steps:

[0051] Step one: according to the number of blades required by the multi-blade micro milling cutter to be processed, the corresponding symmetric multiple frequency typical crystal surface of single crystal diamond is selected, and the radius of the single crystal diamond sphere of the multi-blade micro milling cutter to be processed and the blade rake angle are determined according to the mechanical properties and processing characteristics of the target processing material of the cutter.

[0052] Step two: complete the grinding preparation and polishing of the single crystal diamond sphere according to the determined radius, and ensure the smoothness of the surface of the single crystal diamond sphere.

[0053] Step three: establish a ball head model of the multi-blade micro milling cutter to be processed for analysis, and combine Figure 1 As shown in the figures, the parameter design is performed with the aid of the axial and radial cross sections, Figure 1 Part (a) shows the schematic diagram of the axial cross section of the ball head model, and part (b) shows the schematic diagram of the radial cross section of the ball head model, so that the axial cross section of the ball head model combined with Figure 2 and the radial cross section of the ball head model combined with Figure 3 are obtained, and the blades with different rake angles can be obtained through parameter design. The radial cross section plane coordinate system of the ball head model is established with the center as the origin, the horizontal direction as the x-axis, and the vertical direction as the y-axis. When the depth direction side wall of the processing groove is in the second quadrant (corresponding to Figure 3 part (a)) and the first quadrant (corresponding to Figure 3 part (b)) of the radial cross section plane coordinate system of the ball head model, the blade rake angle can be in a positive rake angle state and a negative rake angle state, respectively. The parameter design is as follows:

[0054] Let the radius of the single crystal diamond sphere be R, the vertical distance between the depth direction side wall of the processing groove and the y-axis of the radial cross section plane coordinate system of the ball head model be s1, the vertical distance between the width direction side wall of the processing groove and the x-axis of the radial cross section plane coordinate system of the ball head model be s2, the axial cross section plane coordinate system of the ball head model be established with the center as the origin, the horizontal direction as the x-axis, and the vertical direction as the y-axis, and the angle between the processing groove and the x-axis of the axial cross section plane coordinate system of the ball head model be the inclination angle ψ.

[0055] In order to make the blade rake angle consistent with the design in the actual use process, s1 should satisfy:

[0056]

[0057] In the formula, α1 is the blade rake angle formed by the depth direction side wall of the processing groove and the surface of the single crystal diamond sphere, r is the radius of the radial cross section, and the relationship between r and the radius R of the single crystal diamond sphere is expressed as:

[0058] r=Rsinψ (2)

[0059] Wherein, the dynamic micro tensile strength distribution of the subsequent single crystal diamond sphere is selected according to the inclination angle ψ.

[0060] For the depth d of the processing groove, there should be a numerical limit, so that the processing grooves are independent of each other, and the cutting performance of each blade is not affected by other blades. When the blade rake angle is in a negative rake angle state, it should satisfy:

[0061]

[0062] In the formula, n is the number of blades, and α2 is the blade rake angle formed by the width direction side wall of the processing groove and the surface of the single crystal diamond sphere, which can be expressed as:

[0063]

[0064] The relationship between the vertical distance s2 and the depth d of the processing groove is expressed as:

[0065] d=rcosα1-s2 (5)

[0066] When the blade rake angle is in a positive rake angle state, it should satisfy:

[0067]

[0068] From formula (1) to formula (6), by giving the single crystal diamond sphere radius R, blade rake angle α1 and use inclination angle ψ of the multi-blade micro-mill to be processed, the depth and width of the processing groove can be determined.

[0069] On this basis, the application of the parameter design method proposed in step three on single crystal diamond requires a detailed explanation of step four to limit the axial and radial positions of the processing groove to meet the requirements of the mechanical properties of single crystal diamond anisotropy. It is worth mentioning that the parameter design method proposed in step three is not limited to single crystal diamond ball head multi-blade micro-mill. Under the condition that the processing conditions meet the requirements, multiple cutting edges that meet the requirements can be prepared on any material.

[0070] Step four: according to the different area conditions of the grinding direction vector on the surface of the single crystal diamond sphere, the phase angle ω of the grinding direction vector and the initial crystal direction is obtained by using the folding symmetry method, and combined with the calculation formula of the dynamic micro tensile strength of the diamond crystal arbitrary crystal face crystal direction proposed by the inventor in the prior application of Chinese invention patent (a diamond ball pressure head design method based on strength factor, CN201510508087.8), the dynamic micro tensile strength distribution of any grinding direction on the surface of the single crystal diamond sphere is further obtained according to the symmetry frequency extension of the single crystal diamond, as follows:

[0071] For any crystal plane P on the surface of the single crystal diamond sphere, combined with Figure 4As shown, the groove is prepared by using the tangential direction as the grinding direction through a grinding disc. A spherical coordinate system with a radius of 1 is established with the center of the single-crystal diamond sphere as the origin, combined with... Figure 5 As shown, the surface of a single-crystal diamond sphere is divided into 48 unit regions by the coordinate axis symmetry planes y = ±x, z = ±x, z = ±y, x = 0, y = 0, and z = 0 of the spherical coordinate system. Based on the axial crystal orientation of the single-crystal diamond sphere, the representative region and the reference region within the crystal plane are determined. The vertically downward direction within any region is defined as the initial crystal orientation. The grinding direction vectors of different regions outside the representative region are moved to the reference region using symmetry and folding methods. The phase angle ω between the grinding direction vectors in different regions and the initial crystal orientation is calculated and substituted into the formula for calculating the dynamic microscopic tensile strength of any crystal plane orientation of diamond crystal, as shown below:

[0072]

[0073] In the formula, σ tdp Let η be the dynamic microscopic tensile strength of any crystal plane orientation, η1 be the weight value of the influence of the {100} crystal plane family on any crystal plane P, η2 be the weight value of the influence of the {110} crystal plane family on any crystal plane P, η3 be the weight value of the influence of the {111} crystal plane family on any crystal plane P, ω be the phase angle generated by any crystal plane P, and ω0 be the phase angle correction coefficient.

[0074] η1, η2, and η3 can also be expressed as:

[0075]

[0076] ω0 can be represented as:

[0077]

[0078] In the formula, m and n are the coordinate values ​​of the normal vector (1,n,m) of any crystal plane P in the spherical coordinate system.

[0079] Step 5: Based on the visualization results of the dynamic microscopic tensile strength distribution of single-crystal diamond, select equally spaced and consistent positions as the cutting edge positions. By removing diamond material at the cutting edge positions, a processing groove is formed to obtain multiple cutting edges with consistent strength and sharpness and uniform wear during processing.

[0080] The application firstly proposes a simple multi-blade micro-milling cutter parameter design method according to the accumulated process experience in the early stage, and then obtains the distribution rule of the dynamic micro tensile strength of single crystal diamond along the surface of the sphere through coordinate transformation and combining the calculation formula of the dynamic micro tensile strength of the diamond crystal arbitrary crystal face crystal direction proposed by the team, and optimizes the reasonable opening position to inhibit the adverse effects of the anisotropy of single crystal diamond on the blade. The method can be used for the design and optimization of high-precision single crystal diamond milling cutter, and improves the geometric precision and service life of the cutter.

[0081] Embodiment

[0082] Combined Figure 5 As shown in the figure, the dynamic micro tensile strength of the groove on the surface of the single crystal diamond sphere with the

[100] crystal direction axis is obtained. In the sphere with the

[100] crystal direction as the axis, considering that the (100) crystal face is 4-fold symmetric, the red line and the green line surrounding area (MEABC) are selected as the representative area, that is, 3 / 48 of the sphere, and the strength of other areas can be obtained by symmetry to the unit area. The representative area is composed of S1 (ABC), S2 (ACE) and S3 (MEC) three areas, wherein, taking S1 area as the reference area, the grinding direction vector falling in S2 area and S3 area needs to be folded symmetrically to S1 area to calculate the phase angle.

[0083] Let O be the origin of the spherical coordinate system, P be any point on the surface of the sphere, the radius of the sphere be 1, σ be the angle between OP and the positive direction of the z-axis, the grinding direction be the vertical downward tangent of the crystal face passing through point P, ON be the projection of OP on the xOy plane, θ be the angle between ON and the positive direction of the x-axis, and the vertical downward direction in the arbitrary crystal face be defined as the initial crystal direction.

[0084] The coordinates (1, m, n) of any point P1 in the S1 area on the sphere can be represented as (sinσcosθ, sinσsinθ, cosσ). According to the foregoing analysis, the grinding direction P1N1 can be represented as (1, tanθ, -tanσ / cosθ), and the vertical downward direction on the arbitrary crystal face is defined as the initial crystal direction of the crystal face. Corresponding initial crystal direction P0N0 can also be represented as (1, tanθ, -tanσ / cosθ), S1 area is the reference area, and the points in the area do not need to be rotated symmetrically. The initial crystal direction P0N0 is in the same direction as the grinding direction P1N1, that is, the phase angle ω1 in the S1 area is 0. In the σ and θ domain of the S1 area, the dynamic micro tensile strength matrix of any point P1 in the S1 area is obtained by substituting the calculation formula (7)-(11) of the dynamic micro tensile strength of the diamond crystal arbitrary crystal face crystal direction.

[0085] On the sphere, the S1 area and the S2 area are symmetric about the plane y=z, so the corresponding point P21 The coordinates of the grinding direction P2N2 after symmetry folding are (sinσcosθ, cosσ, sinσsinθ). Similarly, the coordinates of the grinding direction P2N2 after symmetry folding in the S2 region are 21 N 21 The coordinates of the grinding direction P2N2 after symmetry folding are (sinσcosθ, cosσ, sinσsinθ). Similarly, the coordinates of the grinding direction P2N2 after symmetry folding in the S2 region are 21 N 21 The phase angle ω2 of the initial crystal direction P0N0 is

[0086]

[0087] The dynamic micro tensile strength matrix of any point P2 in the S2 region is obtained by substituting the dynamic micro tensile strength calculation formula (7)-(11) of the arbitrary crystal face crystal direction of the diamond crystal.

[0088] For the S3 region, any point P3 in the S3 region is first symmetry folded to the S2 region, and then symmetry folded to the S1 region, to obtain the vector P 31 The coordinates of the grinding direction P2N2 after symmetry folding are (sinσcosθ, cosσ, sinσsinθ). Similarly, the coordinates of the grinding direction P2N2 after symmetry folding in the S2 region are 31 N 31 The coordinates of the grinding direction P2N2 after symmetry folding are (sinσcosθ, cosσ, sinσsinθ). Similarly, the coordinates of the grinding direction P2N2 after symmetry folding in the S2 region are 31 N 31 The phase angle ω3 of the initial crystal direction P0N0 is

[0089]

[0090] The dynamic micro tensile strength matrix of any point P3 in the S3 region is obtained by substituting the dynamic micro tensile strength calculation formula (7)-(11) of the arbitrary crystal face crystal direction of the diamond crystal.

[0091] The dynamic micro tensile strength distribution rule of the hemisphere can be obtained by extending the multiple symmetry of the single crystal diamond. The visualization result of the (100) crystal face of the single crystal diamond with 4-fold symmetry is combined with Figure 6The dynamic micro tensile strength distribution corresponding to the grinding direction is obtained, and then the parameter design method is used to select the same point of the dynamic micro tensile strength value to prepare multiple cutting edges uniformly distributed on the single crystal diamond. Before machining the cutting edges of the ball head micro milling cutter, the top of the single crystal diamond ball is removed to reduce the diamond removal amount in the fine grinding process, improve the blade making efficiency and reduce the area with low linear velocity. The removal amount of the top of the single crystal diamond ball cannot exceed the midpoint of the length direction of the groove, and the smaller the removal amount is, the longer the effective cutting edge is. Finally, the single crystal diamond multi-blade micro milling cutter prepared based on the design method is combined with the ball head micro milling cutter to form a single crystal diamond ball head micro milling cutter with multiple cutting edges. Figure 7 As shown in FIG. 1.

[0092] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other embodiments without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being indicated by the appended claims rather than that of the above description, and it is intended to embrace all changes and modifications that fall within the meaning and scope of equivalents of the claims. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

[0093] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that can be understood by a person skilled in the art.

Claims

1. A method of designing a single crystal diamond ball-end micro-endmill, characterized in that: The method comprises the following steps: Step 1: according to the number of blades required by the multi-blade micro milling cutter to be processed, a corresponding symmetric multiple frequency single crystal diamond typical crystal surface is selected, and the single crystal diamond ball radius and the blade rake angle of the multi-blade micro milling cutter to be processed are determined according to the mechanical properties and processing characteristics of the target processing material of the cutter; Step 2: the single crystal diamond ball is prepared and polished according to the determined radius; Step 3: a ball head model of the multi-blade micro milling cutter to be processed is established for analysis, and parameter design is performed by means of axial and radial cross sections, respectively, to obtain blades with different rake angles, a radial cross section plane coordinate system of the ball head model is established with the center of the circle as the origin, the horizontal direction as the x-axis and the vertical direction as the y-axis, wherein when the depth direction side wall of the processing groove is in the second quadrant and the first quadrant of the radial cross section plane coordinate system of the ball head model, the blade rake angle is in a positive rake angle state and a negative rake angle state, respectively; Step 4: according to the different area conditions of the grinding direction vector on the surface of the single crystal diamond ball, the phase angle ω of the grinding direction vector and the initial crystal direction is obtained by using the folding symmetry method, and the dynamic micro tensile strength distribution of the single crystal diamond ball surface in any grinding direction is obtained according to the single crystal diamond symmetric multiple frequency by combining the calculation formula of the dynamic micro tensile strength of the diamond crystal in any crystal surface; Step 5: according to the dynamic micro tensile strength distribution result of the single crystal diamond, positions with equal intervals and consistent values are selected as the blade opening positions, the processing grooves are formed by removing the diamond material at the blade opening positions, and a plurality of consistent blades are obtained; The parameter design of step 3 is as follows: Let the radius of the single crystal diamond ball be R, the vertical distance between the depth direction side wall of the processing groove and the y-axis of the radial cross section plane coordinate system of the ball head model be s1, the vertical distance between the width direction side wall of the processing groove and the x-axis of the radial cross section plane coordinate system of the ball head model be s2, the axial cross section plane coordinate system of the ball head model be established with the center of the circle as the origin, the horizontal direction as the x-axis and the vertical direction as the y-axis, and the angle between the processing groove and the x-axis of the axial cross section plane coordinate system of the ball head model be the use inclination angle ψ; In order to make the blade rake angle consistent with the design in the actual use process, s1 should satisfy: In the formula, α1 is the blade rake angle formed by the depth direction side wall of the processing groove and the surface of the single crystal diamond ball, r is the radius of the radial cross section, and the relationship between r and the radius R of the single crystal diamond ball is represented as: r=Rsinψ (2) Wherein, the use inclination angle ψ is selected according to the dynamic micro tensile strength distribution of the single crystal diamond ball; When the blade rake angle is in a negative rake angle state, it should satisfy: In the formula, n is the number of blades, α2 is the blade rake angle formed by the width direction side wall of the processing groove and the surface of the single crystal diamond ball, and is represented as: The relationship between the vertical distance s2 and the cutting depth d of the processing groove is represented as: d=rcosα1-s2 (5) When the blade rake angle is in a positive rake angle state, it should satisfy: According to the formula (1) to formula (6), by giving the single crystal diamond ball radius R, the blade rake angle α1 and the use inclination angle ψ of the multi-blade micro milling cutter to be processed, the depth and width of the processing groove can be determined.

2. The method of designing a single crystal diamond ball-end multi- blade micro-mill according to claim 1, wherein: The step four of the dynamic micro tensile strength distribution obtaining is specifically as follows: For any crystal face P of the single crystal diamond sphere surface, a groove is prepared by a grinding disc with a tangent direction of the crystal face as a grinding direction, a spherical coordinate system with a radius of 1 is established with a ball center of the single crystal diamond sphere as an origin, the single crystal diamond sphere surface is divided into 48 unit regions by the coordinate axis symmetry planes y = ±x, z = ±x, z = ±y, x = 0, y = 0 and z = 0 of the spherical coordinate system, a representative region and a reference region in the representative region of the crystal face are determined according to an axial crystal direction of the single crystal diamond sphere, an initial crystal direction is defined as a vertically downward direction in any region, the grinding direction vectors of different regions outside the representative region are moved to the reference region by means of symmetry and folding, a phase angle ω of the grinding direction vectors and the initial crystal direction in different regions is calculated, and the phase angle ω is substituted into a calculation formula of the dynamic micro tensile strength of the crystal direction of any crystal face of the diamond crystal, and the calculation formula is expressed as follows: In the formula, σ tdp is the dynamic micro-tensile strength of an arbitrary crystal plane orientation, η1 is the weight value of the {100} crystal plane family affecting an arbitrary crystal plane P, η2 is the weight value of the {110} crystal plane family affecting the arbitrary crystal plane P, η3 is the weight value of the {111} crystal plane family affecting the arbitrary crystal plane P, ω is the phase angle generated by the arbitrary crystal plane P, and ω0 is a phase angle correction coefficient. η1, η2 and η3 are expressed as: ω0 is expressed as: In the formula, m and n are coordinate values of a normal vector (1, n, m) of the crystal face P in the spherical coordinate system.

3. The method of designing a single crystal diamond ball-end multi-lip micro end mill according to claim 1, wherein: In the step five, before the diamond material is removed at the split blade position, the top of the single crystal diamond sphere is removed, and the removal amount is not more than a midpoint in a length direction of the processing groove.

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