A ball-end milling cutter with a micro-groove structure for reducing cutting forces in surface machining of carbon fiber composites

Abstract

A ball-end milling cutter with a micro-grooved structure for reducing cutting forces during surface machining of carbon fiber composites comprises a toolholder, a fixed-radius continuous cutting edge, a fixed-radius micro-grooved cutting edge, and a ball-end micro-grooved cutting edge. Based on the cutting force control concept of "discretization of cutting width," the ball-end milling cutter structure with micro-grooved cutting edges divides the entire continuous edge into multiple cutting units, thereby effectively reducing the cutting forces during machining. The total length of the fixed-radius micro-grooved cutting edge and the ball-end micro-grooved cutting edge is l, the micro-grooves have a deflection angle α, and the micro-grooves are l long. a , the micro groove width is 1 b The cutting edge length between two adjacent micro-grooves is equal to the micro-groove length, and the minimum vertical distance h between adjacent main cutting edge micro-grooves is min There is a clear logical relationship between the processing inclination angle and the micro-groove structure, and there is a constraint relationship in the adjustment of parameters, which can ensure the stability of the ball end milling cutter performance. After adjusting the main parameters according to needs, a series of milling cutters with micro-grooved ball end structures that can adapt to different processing conditions can be formed.

Description

Technical Field

[0001] The present invention belongs to the technical field of cutting processing of difficult-to-process materials, and relates to a ball-end milling cutter with a micro-groove structure for reducing the cutting force of milling processing on the surface of carbon fiber composite materials. Background Art

[0002] Carbon fiber reinforced plastic (CFRP) boasts advantages such as high specific strength, high specific stiffness, and customizable properties, extending its application from simple flat structures in high-end equipment to complex curved structures. During the manufacturing process, these curved structures, due to their large size and thin walls, often require separation into multiple curved components, which are then individually formed and assembled. To ensure the precise assembly of these complex curved components, milling of the surfaces to be joined is required prior to assembly. However, CFRP itself exhibits strong anisotropy and layered properties, making it a typically difficult material to machine. Curved CFRP components, in particular, often have thin walls, making them susceptible to deformation during material removal due to milling forces. Ball-end milling cutters are widely used for surface milling of curved components due to their strong normal vector adaptability. However, the complex cutting edge structure and unique machining method, which requires a set machining angle, can also complicate the CERP material removal process. This deformation can severely impact the assembly performance of curved CFRP components and even render the entire equipment useless.

[0003] The "solid carbide fish-scale milling cutter" invented by Tang Chensheng et al., patent application number 200910013142.0, relates to a milling cutter used for milling composite materials such as carbon fiber and glass fiber. By increasing the number of cutting edges to 24, it improves cutting efficiency and reduces milling forces to a certain extent compared to double-edge and four-edge milling cutters. Cheng Moli et al. invented "A micro-tooth milling cutter cutting edge and micro-tooth milling cutter," patent application number 202210458770.5. This series of micro-tooth milling cutters has a clear logical relationship between the number of edges, left-hand helix angle, right-hand helix angle, and edge length. The adjustment of these parameters is constrained, enabling milling instead of grinding, thereby reducing material damage. The aforementioned patents all apply to straight-edge milling cutters for side milling of flat metal or composite components and are not suitable for surface milling of curved CFRP components. Moreover, compared with flat CFRP, the contact state between the cutting edge and the material of curved CFRP components is more complicated. The micro-tooth structure of the cutting edge of the above-mentioned tool cannot be applied to the surface milling of CFRP with the complex curved blade structure of the ball-end milling cutter, making it difficult to achieve effective control of deformation. Summary of the Invention

[0004] The problem that this invention aims to solve is that during the milling process of the surface of difficult-to-machine thin-walled CFRP curved surface components, the overall rigidity of the components is relatively weak, and the complex structure makes it difficult to achieve fully constrained clamping. During the machining process, the components are easily affected by the milling force, and the machining deformation is difficult to control. To this end, based on the study of the CFRP material removal behavior of ball-end milling cutters, the cutting force control concept of "discretization of cutting width" was summarized and proposed. Considering the relationship between the tool structure and the critical conditions for effectively removing CFRP materials, a design method for ball-end milling cutters with micro-grooves that can fully utilize the design concept of "discretization of cutting width" was proposed. A high-precision, low-damage ball-end milling cutter with a micro-groove structure was designed for milling CFRP curved surfaces. By reducing the milling force during the machining process, deformation during the machining process was effectively reduced.

[0005] The technical solution of the present invention:

[0006] A ball-end milling cutter with a micro-groove structure for reducing cutting forces in surface machining of carbon fiber composites, comprising a tool shank L1, a fixed-radius continuous cutting edge L2, a fixed-radius micro-groove cutting edge L3, and a ball-end micro-groove cutting edge L4;

[0007] n microgrooves are opened on the ball head portion of the entire cutting edge of the ball end milling cutter and the fixed radius continuous cutting edge L2 near the ball head to form a fixed radius microgrooved cutting edge L3 and a ball end microgrooved cutting edge L4; the microgrooves have a certain deflection angle α relative to the cutting edge, and the value range of α is 5 to 15 degrees counterclockwise with the center of the microgroove as the rotation point; the total length l of the fixed radius microgrooved cutting edge L3 and the ball end microgrooved cutting edge L4 is not less than 2R0tanβ0 to ensure that the cutting edge with microgrooves is used throughout the machining process; where R0 is the tool The radius is in the range of 4mm to 20mm; β0 is the cutting edge helix angle, which is in the range of 5° to 35°; in order to ensure the cutting stability and dynamic balance of the tool, the number of microgrooves on each cutting edge is the same; according to the processing characteristics of the ball end mill, the processing rake angle β is set in the range of 5 to 30°, the chip groove width w0 of the fixed radius microgrooved cutting edge L3 is in the range of 1mm to 4mm, the chip groove width w1 of the ball end microgrooved cutting edge L4 is in the range of 1mm to 4mm, the ball end radius R = R0, the number of cutting edges N j ≥2;

[0008] The micro groove length of the fixed radius micro groove cutting edge L3 is l a1 , the micro groove width is l b1 , the cutting edge length between adjacent microgrooves is equal to the microgroove length, and the microgroove length and width satisfy the following calculation formula:

[0009]

[0010] The micro groove length of the ball head with micro groove cutting edge L4 is l a2 , the micro groove width is lb2 , the cutting edge length between adjacent microgrooves is equal to the microgroove length, and the microgroove length and width satisfy the following calculation formula:

[0011]

[0012] It is necessary to ensure that the fiber can be removed by the cutting edge under the action of the machining rake angle β, and the minimum vertical distance h between the adjacent cutting edges of the fixed radius micro-groove cutting edge L3 is 1min Satisfy the calculation formula:

[0013]

[0014] Minimum vertical distance h between adjacent cutting edges of ball head with micro groove cutting edge L4 2min Satisfy the calculation formula:

[0015]

[0016] Beneficial effects of the present invention: A ball-end milling cutter with a micro-groove structure for reducing the cutting force in surface machining of carbon fiber composites. Considering the interaction between the cutting edge structure of the ball-end milling cutter and CFRP during the cutting process, based on the "cutting width discretization" cutting force suppression principle, the relevant structural parameters of the ball-end milling cutter with a micro-groove structure are designed, such as the overall length of the fixed radius continuous cutting edge part and the cutting edge part with a micro-groove structure, the micro-groove length, the micro-groove width, the micro-groove deflection angle, the minimum vertical distance of the micro-grooves of adjacent cutting edges, etc., and the relevant calculation methods are given. After adjusting the main parameters according to the needs, a series of ball-end milling cutters with micro-groove structures that are suitable for different machining conditions can be formed. The ball-end milling cutter with a micro-groove structure can effectively reduce the machining milling force while ensuring the milling quality of CFRP, thereby suppressing machining deformation and meeting the low damage and high precision machining requirements of CFRP. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The ball-end milling cutter structure with micro-grooves. (a) is the main view, and (b) is the bottom view. Among them: L1 shank part, L2 fixed radius continuous cutting edge, L3 fixed radius with micro-grooves cutting edge, L4 ball head with micro-grooves cutting edge, β0 fixed radius cutting edge part helix angle, w0 fixed cutting radius part chip groove width, w1 variable cutting radius part chip groove width, N j The number of cutting edges, n the number of micro grooves, R0 tool radius, R ball head radius, and eccentricity are 0.04±0.01mm.

[0018] Figure 2 for Figure 1 AA cross-sectional view, where the core thickness is φ6±0.1.

[0019] Figure 3 for Figure 1 A partial enlarged view of the microgroove at position B.

[0020] Figure 4 Schematic diagram of the microgroove arrangement of a ball-end milling cutter with a microgroove structure. (a) is the fixed cutting radius part, and (b) is the ball-end cutting edge part. The microgroove length of the fixed cutting radius part is l a1 , the micro groove width is l b1 , the cutting edge length between adjacent micro grooves is equal to the micro groove length, and the micro groove length of the ball head part is l a2 , the micro groove width is l b2 , the cutting edge length between adjacent microgrooves is equal to the microgroove length, and the microgroove deflection angle is α. The vertical minimum distances between adjacent main cutting edge microgrooves are h 1min and h 2min . DETAILED DESCRIPTION

[0021] The following further illustrates the specific implementation methods of the present invention in conjunction with the accompanying drawings and technical solutions.

[0022] Taking the milling of T800 grade CFRP curved surface components as an example, the length of the shank part L1 is 50mm, the length of the fixed radius continuous cutting edge is 17mm, the length of the fixed radius micro-groove cutting edge L3 is 10mm, and the length of the ball head micro-groove cutting edge L4 is 5mm. The helix angle β0 of the fixed cutting edge part is 25°~30°, the chip groove width w0 of the fixed cutting radius part is 6mm, the chip groove width w1 of the ball head cutting part is 6mm, and the number of cutting edges N is 10mm. j The number of micro grooves n is 4, the number of micro grooves is 9, the tool radius R0 is 5 mm, and the ball head radius R is 5 mm.

[0023] According to the calculation method in the technical solution, the fixed radius with micro groove cutting edge part: micro groove length l a1 2mm, micro groove width 1 b1 The vertical minimum distance h between adjacent microgrooves is 1 mm, the cutting edge length between adjacent microgrooves is 2 mm, and the microgroove deflection angle α is 8°. 1min 0.5mm. Ball head cutting edge part: micro groove length l a2 1.8mm, micro groove width 1 b2 The vertical minimum distance h between adjacent microgrooves on the main cutting edge is 0.8 mm, and the cutting edge length between adjacent microgrooves is 1.8 mm. 2min The machining angle β is 15°.

[0024] Milling of a thin-walled CFRP curved surface component with a component thickness of 5 mm was performed using the following process parameters: a feed rate of 3000 rpm and a feed rate of 300 mm / min. The machining tools used were a conventional continuous-edge ball-end milling cutter and a ball-end milling cutter with a micro-grooved structure designed to suit the characteristic curvature of the thin-walled CFRP curved surface component. Both tool materials were K44UF carbide, which exhibits excellent wear resistance and toughness. The experiment used tool structure (micro-grooved cutting edge vs. continuous cutting edge) as the single variable; all other tool structures were identical. Results showed that the maximum cutting force experienced by the micro-grooved ball-end milling cutter during cutting was reduced by approximately 43%, and machining deformation was reduced by 39%. While maintaining a constant cutting depth, the micro-grooved ball-end milling cutter splits the continuous material removal process into multiple micro-element cuts, reducing the effective cutting width and thus the milling force, thereby minimizing machining deformation. This approach enables low-damage, high-precision machining of thin-walled CFRP curved surface components, demonstrating promising engineering prospects.

Claims

1. A ball-end milling cutter with a micro-groove structure for reducing cutting force in surface machining of carbon fiber composites, characterized in that: The ball-end milling cutter with a micro-groove structure comprises a cutter handle (L1), a fixed-radius continuous cutting edge (L2), a fixed-radius cutting edge with micro-grooves (L3), and a ball-end cutting edge with micro-grooves (L4); n microgrooves are formed on the ball head portion of the entire cutting edge of the ball end milling cutter and the fixed radius continuous cutting edge (L2) near the ball head to form a fixed radius microgrooved cutting edge (L3) and a ball end microgrooved cutting edge (L4); the microgrooves have a certain deflection angle α relative to the cutting edge, and the value range of α is 5 to 15 degrees counterclockwise with the center of the microgroove as the rotation point; the total length l of the fixed radius microgrooved cutting edge (L3) and the ball end microgrooved cutting edge (L4) is not less than 2R0tanβ0 to ensure that the cutting edge with microgrooves is used throughout the machining process; wherein, R0 is the radius of the tool, and its value range is 4mm~20mm; β0 is the cutting edge helix angle, and its value range is 5°~35°; to ensure the cutting stability and dynamic balance of the tool, the number of microgrooves on each cutting edge is the same; according to the processing characteristics of the ball-end milling cutter, the processing rake angle β is set to a value range of 5~30°, the chip groove width w0 of the fixed radius microgrooved cutting edge (L3) is in the range of 1mm~4mm, the chip groove width w1 of the ball-end microgrooved cutting edge (L4) is in the range of 1mm~4mm, the ball head radius R=R0, the number of cutting edges N j ≥2; The micro groove length of the fixed radius micro groove cutting edge (L3) is l a1 , the micro groove width is l b1 , the cutting edge length between adjacent microgrooves of the fixed radius microgroove cutting edge (L3) is equal to the microgroove length of the fixed radius microgroove cutting edge (L3), and the microgroove length and microgroove width of the fixed radius microgroove cutting edge (L3) satisfy the following calculation formula: The micro groove length of the ball head with micro groove cutting edge (L4) is l a2 , the micro groove width is l b2 , the cutting edge length between adjacent microgrooves of the ball head microgroove cutting edge (L4) is equal to the microgroove length of the ball head microgroove cutting edge (L4), and the microgroove length and microgroove width of the ball head microgroove cutting edge (L4) satisfy the following calculation formula: It is necessary to ensure that the fiber can be removed by the cutting edge under the action of the machining rake angle β, and the minimum vertical distance h between the adjacent cutting edges of the fixed radius micro-groove cutting edge (L3) is 1min Satisfy the calculation formula: Minimum vertical distance h between adjacent cutting edges of ball-end micro-grooved cutting edge (L4) 2min Satisfy the calculation formula:

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