Design method of single crystal diamond ball head multi-cutting-edge micro milling cutter

Abstract

The invention discloses a design method of a single crystal diamond ball head multi-cutting-edge micro milling cutter, and relates to the technical field of single crystal diamond cutter manufacturing. Selecting typical crystal faces of the single crystal diamond with symmetrical frequency doubling according to the number of blades, and determining the sphere radius and the front angle of the blades of the single crystal diamond; grinding, preparing and polishing a single crystal diamond sphere; establishing a ball head model of the to-be-machined multi-cutting-edge micro-milling cutter, and performing parameter design by means of axial and radial section cutting planes; a folding symmetry method is adopted to obtain a phase angle between a grinding direction vector and an initial crystal orientation, and dynamic microcosmic tensile strength distribution of the surface of the single crystal diamond sphere in any grinding direction is obtained through expansion and extension; and according to a result, selecting equidistant positions with consistent numerical values as edging positions to obtain a blade. The removal size and the edging position of the monocrystal diamond required for forming the blade are optimized, so that the adverse effect of the anisotropy of the mechanical property of the monocrystal diamond on the preparation and cutting performance of the micro-milling cutter can be weakened, and the independent and flexible design of the blade angle and parameters is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal diamond tool manufacturing, in particular to a design method for a single crystal diamond ball-end multi-edge micro-milling cutter. Background Art

[0002] With the continuous advancement of science and technology, the fields of micro-electromechanical system manufacturing technology, bioengineering, optical engineering, etc. have put forward more stringent requirements on the level of ultra-precision machining, especially in the field of ultra-precision machining of complex optical molds with high hardness and difficult-to-machine materials (such as WC). Micro-milling has flexible machining adaptability and can achieve ultra-smooth machining of micro-complex structures. However, the traditional single-edge single-crystal diamond micro-milling cutter has low durability and milling efficiency, which is difficult to meet the current industrial needs. Therefore, it is urgent to develop the manufacturing technology of single-crystal diamond multi-edge micro-milling cutter.

[0003] Since the mechanical and physical properties of single crystal diamond are severely anisotropic, the grinding performance of different crystal planes and crystal orientations varies greatly, and the cutting edge of the sharpened multi-edge micro-milling cutter has poor symmetry, which affects the quality of the machined surface and the number of cutting edges involved in milling. Therefore, the design and structure of the single crystal diamond ball-end multi-edge micro-milling cutter are crucial to its cutting performance. Based on the above analysis, it can be seen that the single crystal diamond multi-edge micro-milling cutter is not a simple scaling of the conventional milling cutter. On the one hand, due to the increase in the ratio of the tool diameter to the cutting thickness, the load per unit volume of the micro-milling cutter is generally dozens of times that of the conventional milling cutter. The same tool features (such as spiral grooves) not only cannot function normally, 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, the processing difficulty of some structural features of the conventional milling cutter increases sharply after being reduced, which may be excessive or impossible to process due to the limitations of manufacturing technology. Therefore, reasonable parameter design is extremely important for the manufacture of single crystal diamond multi-edge micro-milling cutters.

[0004] In addition, currently, micro-milling cutters generally use artificial PCD polycrystalline diamond as tool material, and the blade shape is mostly simple geometric polygons. PCD diamond is mainly made of diamond particles and binders by high-pressure sintering. Due to the randomness of the shape and distribution of the abrasive particles, it is impossible to produce micro-milling cutters with extremely high sharpness. Compared with isotropic PCD polycrystalline diamond with binders, natural single crystal diamond has higher hardness and can produce extremely sharp cutting edges. For example, through the reasonable selection of crystal planes and crystal directions, a balance between wear resistance and sharpness can be achieved. However, natural single crystal diamond has extremely high hardness and strong anisotropy. The preparation of tools requires reasonable parameter design and planning of grinding crystal directions. Therefore, studying the design method of single crystal diamond micro-milling cutters can not only improve the preparation level of micro-milling cutters, but also play an important role in the development of ultra-precision machining technology. Summary of the invention

[0005] In order to address the shortcomings of the background technology, the present invention provides a design method for a single crystal diamond ball-end multi-blade micro-milling cutter, which helps to reduce the adverse effects of the anisotropy of the mechanical properties of single crystal diamond on the preparation and cutting performance of the micro-milling cutter by optimizing the removal size and cutting position of the single crystal diamond required to form the blade, and ensures the independent and flexible design of the blade angle and parameters.

[0006] To achieve the above object, the present invention adopts the following technical scheme: a design method of a single crystal diamond ball-end multi-edge micro-milling cutter, comprising the following steps:

[0007] Step 1: According to the number of blades required for the multi-blade micro-milling cutter to be processed, select the typical crystal plane of single crystal diamond with corresponding symmetrical frequency doubling, and determine the radius of the single crystal diamond sphere and the blade rake angle of the multi-blade micro-milling cutter to be processed according to the mechanical properties and processing characteristics of the target processing material of the tool;

[0008] Step 2: completing the grinding preparation and polishing of the single crystal diamond sphere according to the determined radius;

[0009] Step 3: Establish a ball head model of the multi-blade micro-milling cutter to be processed for analysis, and perform parameter design with the aid of axial and radial sections. Through parameter design, blades with different rake angles are obtained. A plane coordinate system of the radial section of the ball head model is established with the center of the circle as the origin, with the horizontal direction being the x-axis and the vertical direction being the y-axis. When the side wall of the processing groove in the depth direction is in the second quadrant and the first quadrant of the plane coordinate system of the radial section of the ball head model, the blade rake angle is in a positive rake angle and a negative rake angle state, respectively.

[0010] Step 4: According to the grinding direction vector in different areas on the surface of the single crystal diamond sphere, the phase angle ω between 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 microscopic tensile strength of any crystal plane and crystal direction of the diamond crystal, the dynamic microscopic tensile strength distribution of any grinding direction on the surface of the single crystal diamond sphere is obtained by extension according to the symmetric frequency doubling of the single crystal diamond;

[0011] Step 5: According to the dynamic microscopic tensile strength distribution results of single crystal diamond, select positions with equal spacing and consistent values ​​as cutting positions, and form processing grooves by removing diamond material at the cutting positions to obtain multiple consistent cutting edges.

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

[0013] Assume that the radius of the single crystal diamond sphere is R, and the vertical distance between the side wall of the machining groove in the depth direction and the y-axis of the plane coordinate system of the radial section of the ball head model is s. 1 The vertical distance between the width sidewall of the machined groove and the x-axis of the radial section plane coordinate system of the ball head model is s. 2, establish the plane coordinate system of the axial section of the ball head model with the center of the circle as the origin, the horizontal direction is the x-axis, the vertical direction is the y-axis, and the angle between the machining groove and the x-axis of the plane coordinate system of the axial section of the ball head model is the use inclination angle ψ;

[0014] To make the blade rake angle consistent with the design during actual use, s 1 Should meet:

[0015]

[0016] In the formula, α 1 is the blade rake angle formed by the side wall of the processing groove in the depth direction and the surface of the single crystal diamond sphere, r is the radius of the radial section, and its relationship with the radius R of the single crystal diamond sphere is expressed as:

[0017] r=Rsinψ (2)

[0018] Wherein, the inclination angle ψ is selected according to the dynamic microscopic tensile strength distribution of the single crystal diamond sphere;

[0019] When the blade rake angle is negative, the following conditions should be met:

[0020]

[0021] Where n is the number of blades, α 2 It is the blade rake angle formed by the width direction side wall of the processed groove and the surface of the single crystal diamond sphere, expressed as:

[0022]

[0023] Vertical distance 2 The relationship with the cutting depth d of the machined groove is expressed as:

[0024] d=rcosα 1 -s 2 (5)

[0025] When the blade rake angle is positive, it should meet the following conditions:

[0026]

[0027] From formula (1) to formula (6), by giving the radius R of the single crystal diamond sphere and the blade rake angle α of the multi-edge micro-milling cutter to be processed 1 And using the inclination angle ψ, the depth and width of the machined groove can be determined.

[0028] Furthermore, the dynamic microscopic tensile strength distribution of step 4 is obtained as follows:

[0029] For any crystal plane P on the surface of a single-crystal diamond sphere, a machining groove is prepared by a grinding disc using its tangent direction as the grinding direction, a spherical coordinate system with a radius of 1 is established with the center of the single-crystal diamond sphere as the origin, and the surface of the single-crystal diamond sphere is equally divided into 48 unit areas by the coordinate axis symmetry planes y=±x, z=±x, z=±y, x=0, y=0 and z=0 of the spherical coordinate system. According to the axial crystal direction of the single-crystal diamond sphere, the representative area of ​​the crystal plane and the reference area therein are determined, and the vertical downward direction in any area is defined as the initial crystal direction. The grinding direction vectors of different areas outside the representative area are moved to the reference area by means of symmetry and folding, and the phase angle ω between the grinding direction vectors in different areas and the initial crystal direction is calculated, and substituted into the calculation formula of the dynamic microscopic tensile strength of any crystal plane direction of the diamond crystal, which is expressed as follows:

[0030]

[0031] In the formula, σ tdp is the dynamic microscopic tensile strength of any crystal plane and crystal direction, η 1 is the weight of the {100} crystal plane family on any crystal plane P, η 2 is the weight of the {110} crystal plane family on any crystal plane P, η 3 is the weight value of the influence of the {111} crystal plane family on any crystal plane P, ω is the phase angle produced by any crystal plane P, ω 0 is the phase angle correction factor;

[0032] η 1 , η 2 and η 3 It is expressed as:

[0033]

[0034] ω 0 It is expressed as:

[0035]

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

[0037] Furthermore, in the step five, before the diamond material at the cutting edge position is removed, the top of the single crystal diamond sphere is removed, and the removal amount does not exceed the midpoint of the length direction of the processed groove.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The method of the present invention takes into account the fine size and weak rigidity of the micro-milling cutter and the high hardness of the single crystal diamond, and establishes a quantitative design method for the characteristic parameters of the tool based on the requirements of the grinding process and the basic characteristics of the ball-end multi-edge micro-milling cutter. The method can achieve efficient processing of materials with different mechanical properties by changing the angle of the blade, thereby increasing the scope of application of the tool and the design method;

[0040] 2. The method of the present invention obtains the dynamic microscopic tensile strength distribution of the surface grinding of the single crystal diamond sphere based on 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, so as to obtain multiple blades with consistent cutting performance and life;

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

[0042] Figure 1 It is a schematic diagram of the cutting position of the cross-section of the ball head model in the design method of the present invention;

[0043] Figure 2 yes Figure 1 Schematic diagram of the axial section of the mid-ball head model;

[0044] Figure 3 yes Figure 1 Schematic diagram of radial section of the mid-ball head model;

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

[0046] Figure 5 It is a schematic diagram of equally divided regions of a spherical coordinate system of a single crystal diamond sphere in the design method of the present invention;

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

[0048] Figure 7 This is a physical picture of the single crystal diamond ball-end multi-edge micro-milling cutter prepared in the example. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0050] like Figure 1 to Figure 5 As shown, a design method of a single crystal diamond ball-end multi-edge micro-milling cutter comprises the following steps:

[0051] Step 1: According to the number of blades required for the multi-blade micro-milling cutter to be processed, select the typical crystal plane of single crystal diamond with corresponding symmetrical frequency doubling, and determine the radius of the single crystal diamond sphere and the blade rake angle of the multi-blade micro-milling cutter to be processed according to the mechanical properties and processing characteristics of the target processing material of the tool.

[0052] Step 2: Complete the grinding preparation and polishing of the single crystal diamond sphere according to the determined radius to ensure that the surface of the single crystal diamond sphere is smooth.

[0053] Step 3: Establish the ball head model of the multi-edge micro milling cutter to be processed for analysis, combined with Figure 1 As shown, the parameters are designed by using the axial and radial sections respectively. Figure 1 Part (a) shows the schematic diagram of the axial section of the ball head model, and part (b) shows the schematic diagram of the radial section of the ball head model. Figure 2 The axial section and joint of the ball head model shown Figure 3 The radial section of the ball head model shown in FIG. 1 can obtain blades with different rake angles through parameter design. The radial 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, and the vertical direction is the y-axis. When the side wall of the processing groove in the depth direction is in the second quadrant of the radial section plane coordinate system of the ball head model (corresponding to Figure 3 (a)) and the first quadrant (corresponding to Figure 3 In part (b), the blade rake angle can be positive or negative, and the parameter design is as follows:

[0054] Assume that the radius of the single crystal diamond sphere is R, and the vertical distance between the side wall of the machining groove in the depth direction and the y-axis of the plane coordinate system of the radial section of the ball head model is s. 1 The vertical distance between the width sidewall of the machined groove and the x-axis of the radial section plane coordinate system of the ball head model is s. 2 , establish the plane coordinate system of the axial section of the ball head model with the center of the circle as the origin, the horizontal direction is the x-axis, the vertical direction is the y-axis, and the angle between the machining groove and the x-axis of the plane coordinate system of the axial section of the ball head model is the inclination angle ψ.

[0055] To make the blade rake angle consistent with the design during actual use, s 1 Should meet:

[0056]

[0057] In the formula, α 1is the blade rake angle formed by the side wall of the processing groove in the depth direction and the surface of the single crystal diamond sphere, r is the radius of the radial section, and its relationship with the radius R of the single crystal diamond sphere is expressed as:

[0058] r=Rsinψ (2)

[0059] The inclination angle ψ is selected based on the subsequent dynamic microscopic tensile strength distribution of the single crystal diamond sphere.

[0060] There should be a numerical limit on the cutting depth d of the machined grooves, so that the machined 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 negative, it should meet the following conditions:

[0061]

[0062] Where n is the number of blades, α 2 The blade rake angle formed by the width direction side wall of the processed groove and the surface of the single crystal diamond sphere can be expressed as:

[0063]

[0064] Vertical distance 2 The relationship with the cutting depth d of the machined groove is expressed as:

[0065] d=rcosα 1 -s 2 (5)

[0066] When the blade rake angle is positive, it should meet the following conditions:

[0067]

[0068] From formula (1) to formula (6), by giving the radius R of the single crystal diamond sphere and the blade rake angle α of the multi-edge micro-milling cutter to be processed 1 And using the inclination angle ψ, the depth and width of the machined groove can be determined.

[0069] On this basis, for the application of the parameter design method proposed in step 3 on single crystal diamond, it is necessary to explain step 4 in detail to limit the axial and radial positions of the machining grooves to meet the requirements of the anisotropy of the mechanical properties of single crystal diamond. It is worth mentioning that the parameter design method proposed in step 3 is not limited to single crystal diamond ball-end multi-edge micro-milling cutters. When the processing conditions meet the requirements, multiple cutting edges that meet the requirements can be prepared on any material.

[0070] Step 4: According to the grinding direction vector in different areas of the surface of the single crystal diamond sphere, the folded symmetry method is used to obtain the phase angle ω between the grinding direction vector and the initial crystal direction, and combined with the calculation formula of the dynamic microscopic tensile strength of any crystal plane and crystal direction of the diamond crystal proposed in the Chinese invention patent (a diamond Bosch indenter design method based on intensity factor, CN201510508087.8) previously applied by the inventor, and then according to the symmetric frequency doubling of the single crystal diamond, the dynamic microscopic tensile strength distribution of any grinding direction on the surface of the single crystal diamond sphere is obtained, as follows:

[0071] For any crystal plane P on the surface of a single-crystal diamond sphere, combined Figure 4 As shown, the tangent direction is used as the grinding direction to prepare the machining groove through the 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. Figure 5 As shown, the surface of the single crystal diamond sphere is divided into 48 unit areas by the axisymmetric planes y=±x, z=±x, z=±y, x=0, y=0 and z=0 of the spherical coordinate system. According to the axial crystal direction of the single crystal diamond sphere, the representative area of ​​the crystal plane and the reference area therein are determined, and the vertical downward direction in any area is defined as the initial crystal direction. The grinding direction vectors of different areas outside the representative area are moved to the reference area by means of symmetry and folding, and the phase angle ω between the grinding direction vectors in different areas and the initial crystal direction is calculated, and substituted into the calculation formula of the dynamic microscopic tensile strength of any crystal plane and crystal direction of the diamond crystal, which is expressed as follows:

[0072]

[0073] In the formula, σ tdp is the dynamic microscopic tensile strength of any crystal plane and crystal direction, η 1 is the weight of the {100} crystal plane family on any crystal plane P, η 2 is the weight of the {110} crystal plane family on any crystal plane P, η 3 is the weight value of the influence of the {111} crystal plane family on any crystal plane P, ω is the phase angle produced by any crystal plane P, ω 0 is the phase angle correction factor.

[0074] η 1 , η 2 and η 3 It can also be expressed as:

[0075]

[0076] ω 0 It can be expressed as:

[0077]

[0078] Where 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 positions with consistent values ​​as the cutting positions, and form processing grooves by removing the diamond material at the cutting positions to obtain multiple cutting edges with consistent strength and sharpness and uniform wear during processing.

[0080] The present invention first proposes a concise multi-blade micro-milling cutter parameter design method based on the process experience accumulated in the early stage, and then obtains the distribution law of the dynamic micro-tensile strength of single-crystal diamond along the surface of the sphere through coordinate transformation and the calculation formula of the dynamic micro-tensile strength of any crystal plane and crystal direction of diamond crystal proposed by this team. Based on this, a reasonable cutting position is selected to suppress the adverse effects of the anisotropy of single-crystal diamond on the blade. This method can be used for the design and optimization of high-precision single-crystal diamond milling cutters to improve the geometric accuracy and service life of the tool.

[0081] Example

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

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

[100] crystal axis, considering that the (100) crystal plane is 4-fold symmetric, the area surrounded by the red and green lines (MEABC) is selected as the representative area, that is, 3 / 48 of the sphere. The strength of other areas can be obtained by symmetry to this unit area. The representative area is represented by S 1 (ABC), S 2 (ACE) and S 3 (MEC) consists of three regions, among which S 1 The area is the reference area, which falls in S 2 Area and S 3 The grinding direction vectors in the area need to be folded symmetrically to S 1 The phase angle is calculated in the region.

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

[0084] S on the sphere 1 Any point P in the region 1 The coordinates (1, m, n) can be expressed as (sinσcosθ, sinσsinθ, cosσ). According to the above analysis, the grinding direction P1 N 1 It can be expressed as (1, tanθ, -tanσ / cosθ). Let the vertical downward direction on any crystal plane be the initial crystal direction of the crystal plane, then the corresponding initial crystal direction P 0 N 0 It can also be expressed as (1, tanθ, -tanσ / cosθ), S 1 The region is a reference region. The points in the region do not need to be rotationally symmetric. The initial crystal orientation P 0 N 0 With grinding direction P 1 N 1 Same direction, i.e. S 1 Phase angle ω in the region 1 = 0. In S 1 The values ​​of σ and θ in the region are taken within the definition domain, and are substituted into the calculation formulas (7)-(11) for the dynamic microscopic tensile strength of any crystal plane or crystal direction of diamond crystal to obtain S 1 Any point P in the region 1 Dynamic micro tensile strength matrix.

[0085] On a sphere, S 1 Area and S 2 The region is symmetric about the plane y=z, so S 2 Any point P in the region 2 Fold symmetrically to S 1 The area can get the corresponding point P 21 Coordinates (sinσcosθ, cosσ, sinσsinθ). In the same way, S 2 Grinding direction P in the area 2 N 2 Symmetric P 21 N 21 It can be expressed as (1, -tanσ / cosθ, tanθ). 2 The values ​​of σ and θ in the region are taken within the definition domain, and the grinding direction P after folding symmetry is calculated according to the following formula 21 N 21 With the initial crystal orientation P 0 N 0 The phase angle ω 2 :

[0086]

[0087] And substitute the calculation formula (7)-(11) of the dynamic micro tensile strength of any crystal plane and crystal direction of diamond crystal to obtain S 2 Any point P in the region 2 Dynamic micro tensile strength matrix.

[0088] For S 3 area, will fall in S3 Any point P in the region 3 First fold symmetrically to S 2 area, and then fold symmetrically to S 1 area, get S 3 Any point P 3 Convert to S 1 The vector P after the region 31 It can be expressed as (cosσ, sinσcosθ, sinσsinθ), grinding direction P 31 N 31 After folding symmetry, it can be expressed as (-tanσ / cosθ,1,tanθ). 3 The values ​​of σ and θ in the region are taken within the definition domain, and S is calculated according to the following formula 3 The grinding direction vector in the region is folded symmetrically after P 31 N 31 With the initial crystal orientation P 0 N 0 Phase angle ω 3 :

[0089]

[0090] And substitute the calculation formula (7)-(11) of the dynamic micro tensile strength of any crystal plane and crystal direction of diamond crystal to obtain S 3 Any point P in the region 3 Dynamic micro tensile strength matrix.

[0091] According to the multiple symmetry of single crystal diamond, the dynamic microscopic tensile strength distribution law of the hemisphere can be obtained by extending and extending. The visualization results of the 4-fold symmetric single crystal diamond (100) crystal plane are combined with Figure 6 As shown. After obtaining the dynamic microscopic tensile strength distribution law corresponding to the grinding direction, the parameter design method can be used to select points with the same dynamic microscopic tensile strength values ​​to prepare multiple blades evenly distributed on the single crystal diamond. This embodiment removes the top of the single crystal diamond sphere before processing the blade of the ball-end micro-milling cutter to reduce the amount of diamond removed during the fine grinding process, improve the blade making efficiency and reduce the area with low linear speed. The amount of top removal of the single crystal diamond sphere cannot exceed the midpoint of the length direction of the machined groove. At the same time, the smaller the removal amount, the longer the effective cutting edge. Finally, the single crystal diamond multi-blade micro-milling cutter prepared based on this design method is combined with Figure 7 shown.

[0092] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms of assembly without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0093] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A design method for a single crystal diamond ball-end multi-edge micro-milling cutter, characterized in that: The following steps are involved: Step 1: According to the number of blades required for the multi-blade micro-milling cutter to be processed, select the typical crystal plane of single crystal diamond with corresponding symmetrical frequency doubling, and determine the radius of the single crystal diamond sphere and the blade rake angle of the multi-blade micro-milling cutter to be processed according to the mechanical properties and processing characteristics of the target processing material of the tool; Step 2: completing the grinding preparation and polishing of the single crystal diamond sphere according to the determined radius; Step 3: Establish a ball head model of the multi-blade micro-milling cutter to be processed for analysis, and perform parameter design with the aid of axial and radial sections. Through parameter design, blades with different rake angles are obtained. A plane coordinate system of the radial section of the ball head model is established with the center of the circle as the origin, with the horizontal direction being the x-axis and the vertical direction being the y-axis. When the side wall of the processing groove in the depth direction is in the second quadrant and the first quadrant of the plane coordinate system of the radial section of the ball head model, the blade rake angle is in a positive rake angle and a negative rake angle state, respectively. Step 4: According to the grinding direction vector in different areas on the surface of the single crystal diamond sphere, the phase angle ω between 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 microscopic tensile strength of any crystal plane and crystal direction of the diamond crystal, the dynamic microscopic tensile strength distribution of any grinding direction on the surface of the single crystal diamond sphere is obtained by extension according to the symmetric frequency doubling of the single crystal diamond; Step 5: According to the dynamic microscopic tensile strength distribution results of single crystal diamond, select positions with equal spacing and consistent values ​​as cutting positions, and form processing grooves by removing diamond material at the cutting positions to obtain multiple consistent cutting edges.

2. The design method of a single crystal diamond ball-end multi-edge micro-milling cutter according to claim 1, characterized in that: The parameter design of step three is as follows: Assume that the radius of the single crystal diamond sphere is R, the vertical distance between the side wall of the processing groove in the depth direction and the y-axis of the plane coordinate system of the radial section of the ball head model is s1, and the vertical distance between the side wall of the processing groove in the width direction and the x-axis of the plane coordinate system of the radial section 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, and the angle between the processing groove and the x-axis of the plane coordinate system of the axial section of the ball head model is the use inclination angle ψ; In order to make the blade rake angle consistent with the design during actual use, s1 should meet the following requirements: Where α1 is the blade rake angle formed by the side wall of the processing groove in the depth direction and the surface of the single crystal diamond sphere, r is the radius of the radial section, and its relationship with the radius R of the single crystal diamond sphere is expressed as: r=Rsinψ (2) Wherein, the inclination angle ψ is selected according to the dynamic microscopic tensile strength distribution of the single crystal diamond sphere; When the blade rake angle is negative, the following conditions should be met: Where n is the number of blades, and α2 is the blade rake angle formed by the side wall of the machined groove in the width direction and the surface of the single crystal diamond sphere, which is expressed as: The relationship between the vertical distance s2 and the cutting depth d of the machined groove is expressed as: d=rcosα1-s2 (5) When the blade rake angle is positive, it should meet the following conditions: From formula (1) to formula (6), by giving the radius R of the single crystal diamond sphere, the blade rake angle α1 and the inclination angle ψ of the multi-edge micro-milling cutter to be processed, the depth and width of the processed groove can be determined.

3. The design method of a single crystal diamond ball-end multi-edge micro-milling cutter according to claim 1, characterized in that: The dynamic microscopic tensile strength distribution of step 4 is obtained as follows: For any crystal plane P on the surface of a single-crystal diamond sphere, a machining groove is prepared by a grinding disc using its tangent direction as the grinding direction, a spherical coordinate system with a radius of 1 is established with the center of the single-crystal diamond sphere as the origin, and the surface of the single-crystal diamond sphere is equally divided into 48 unit areas by the coordinate axis symmetry planes y=±x, z=±x, z=±y, x=0, y=0 and z=0 of the spherical coordinate system. According to the axial crystal direction of the single-crystal diamond sphere, the representative area of ​​the crystal plane and the reference area therein are determined, and the vertical downward direction in any area is defined as the initial crystal direction. The grinding direction vectors of different areas outside the representative area are moved to the reference area by means of symmetry and folding, and the phase angle ω between the grinding direction vectors in different areas and the initial crystal direction is calculated, and substituted into the calculation formula of the dynamic microscopic tensile strength of any crystal plane direction of the diamond crystal, which is expressed as follows: In the formula, σ tdp is the dynamic microscopic tensile strength of any crystal plane and crystal orientation, η1 is the weight value of the influence of the {100} crystal plane family on any crystal plane P, η2 is the weight value of the influence of the {110} crystal plane family on any crystal plane P, η3 is the weight value of the influence of the {111} crystal plane family on any crystal plane P, ω is the phase angle generated by any crystal plane P, and ω0 is the phase angle correction coefficient; η1, η2 and η3 are expressed as: ω0 is expressed as: Where m and n are the coordinate values ​​of the normal vector (1, n, m) of any crystal plane P in the spherical coordinate system.

4. The design method of a single crystal diamond ball-end multi-edge micro-milling cutter according to claim 1, characterized in that: In the step 5, before the diamond material is removed at the position of the cutting edge, the top of the single crystal diamond sphere is removed, and the amount of removal does not exceed the midpoint of the length direction of the processed groove.

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