Master-slave multi-blade staggered-tooth milling cutter structure with reinforced shearing and cutting functions

Abstract

The invention relates to a master-slave multi-edge staggered tooth milling cutter structure with a reinforced shearing and cutting function. The milling cutter structure comprises a left-handed main cutting edge, a right-handed main cutting edge, a left-handed main chip groove, a right-handed main chip groove, left-handed micro teeth, a left-handed micro tooth slave edge, right-handed micro teeth, a right-handed micro tooth slave edge and other micro teeth. A micro-tooth slave edge is formed in a cutting edge strip of a traditional staggered-tooth cutter, and the micro-tooth slave edge and a main cutting edge alternately cut materials. When the cutter rotates, materials on the upper edge and the lower edge of a workpiece are sheared and cut in the strong constraint direction through the left rotating main cutting edge and the right rotating main cutting edge, a thermoplastic composite material with high toughness is extruded and deformed under the cutting action, and at the moment, a surface fiber back support is strengthened due to extrusion deformation. And the left-handed micro-tooth slave blade and the right-handed micro-tooth slave blade shear and remove the material which is not removed in the strong constraint direction again in a reciprocating and alternating manner, so that multiple times of reinforced shearing and cutting of the material are realized. The design is beneficial for removing materials in a surface layer weak constraint state, surface layer damage is inhibited, and low-damage milling of the thermoplastic composite material is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of milling tools in mechanical processing, and relates to a master-slave multi-blade staggered tooth milling tool structure with enhanced shearing and cutting functions. Background Art

[0002] Carbon fiber reinforced thermoplastic composites (hereinafter referred to as "thermoplastic composites") have attracted more and more attention in the aerospace field due to their advantages such as light weight, high strength and better impact resistance. In order to meet the assembly and connection requirements of thermoplastic composite components, a large amount of edge milling is often required. However, thermoplastic composites are composed of high-strength carbon fibers and viscous and tough heat-sensitive resins at a microscopic level. The essence of processing thermoplastic composites is the co-cutting and removal process of fibers and resins. Due to the strong plasticity and high elongation at break of thermoplastic resins, the workpiece is deformed more during cutting and the fibers are more difficult to cut. The uncut thermoplastic resin and fibers are combined, and the surface is prone to flaky flash damage. These irreversible damages lead to poor processing quality, seriously affecting the assembly accuracy and efficiency of the processing, thereby reducing the service performance of the components and restricting the application of thermoplastic composites.

[0003] Due to the urgent need for high-performance composite materials in the aerospace field, many scholars at home and abroad have conducted a lot of fruitful research on the processing of thermoplastic composites, but most of them focus on process optimization. At present, there is still no tool structure specifically suitable for thermoplastic composite milling. Thermoplastic composites themselves are composed of fiber reinforcement phase and resin matrix phase, which makes them anisotropic and inhomogeneous. The toughness and thermal sensitivity of thermoplastic resins make it easy to form unique long chips and adhere to the tool during processing, and the tool cutting ability is worse. This makes its processing process and damage form completely different from metals and traditional carbon fiber reinforced thermosetting composites (hereinafter referred to as "thermosetting composites"), and the milling tools used for the two are also not applicable. For example, Wang et al. optimized a micro-tooth cutter in a paper titled "Structural optimization method of multitooth cutter for surface damages suppression in edge trimming of Carbon Fiber Reinforced Plastics" published in Volume 46 of the Journal of Manufacturing Processes. The optimized tool can effectively suppress the milling damage on the surface of thermosetting composites under any processing parameters. However, this tool suffered from severe chip adhesion to the tool when milling thermoplastic composites, resulting in serious processing damage. For another example, Zhang Feng et al. of Guohong Tool System (Wuxi) Co., Ltd. published an invention patent with the patent application number "CN202011546388.7" in 2020, "A High-efficiency Milling Tool for Heat-resistant Alloys", which is specifically used for milling titanium alloy blades in the field of aviation engines. However, this type of tool did not take into account the problem of high-strength fibers and viscous resins being difficult to cut during design, and could not effectively suppress the flash damage generated on the surface during the milling of thermoplastic composites. Therefore, there is an urgent need to develop new cutting tools specifically suitable for thermoplastic composites to meet the needs of high-quality and efficient milling processing of components. Summary of the invention

[0004] The present invention aims to solve the problem that the surface material is difficult to be effectively cut off under weak constraint in the milling process of thermoplastic composites, thus causing damage such as burrs and flashes, and invents a master-slave multi-blade staggered tooth milling tool structure with enhanced shearing and cutting function. That is, the staggered arrangement of left-handed cutting edges and right-handed cutting edges can respectively realize the simultaneous inward shearing and cutting of the upper and lower surface layers of the composite material, so that the upper and lower surface materials are removed under strong constraint. At the same time, micro-toothed slave blades with the same hand direction but different helix angles are respectively opened on the left-handed cutting edges, i.e., the main blades. When the tool rotates, the main cutting edge first shears and cuts the surface material in the strong constraint direction, and the thermoplastic composite with strong toughness is extruded and deformed under the cutting action. At this time, the back support of the surface fiber is strengthened due to the extrusion deformation, and then the micro-toothed slave blade with a larger helix angle performs a second enhanced shearing and cutting of the surface material in the strong constraint direction, thereby realizing multiple shearing and cutting of the surface material in the strong constraint direction, thereby effectively suppressing the surface milling damage.

[0005] The technical solution of the present invention:

[0006] A main-slave multi-blade staggered tooth tool structure with enhanced shear cutting function, comprising a main part and an improved part; the main part is a staggered tooth tool structure, comprising a left-handed main cutting edge 1, a right-handed main cutting edge 2, a left-handed main chip groove 3 and a right-handed main chip groove 4; the improved part is a left-handed micro-tooth 5, a left-handed micro-tooth following edge 8, a right-handed micro-tooth 6 and a right-handed micro-tooth following edge 7; the left-handed micro-tooth 5 is opened in the edge band of the left-handed main cutting edge 1, and the upper edge of the micro-tooth is modified to the left-handed micro-tooth following edge 8; the right-handed micro-tooth 6 is opened in the edge band of the right-handed main cutting edge 2, and the lower edge of the micro-tooth is modified to the right-handed micro-tooth following edge 7, the angle between the left-handed main cutting edge 1 and the milling cutter axis is P1, the angle between the right-handed main cutting edge 2 and the milling cutter axis is P2, the angle between the left-handed micro-tooth following edge 8 and the milling cutter axis is P3, and the angle between the right-handed micro-tooth following edge 7 and the milling cutter axis is P4, as shown in FIG. Figure 1 When the tool rotates, the left-handed micro-toothed blade 8 and the left-handed main cutting edge 1 cut alternately, and the right-handed micro-toothed blade 7 and the right-handed main cutting edge 2 cut alternately, producing an enhanced shear cutting effect.

[0007] The left-handed micro-toothed blade and the right-handed micro-toothed blade are ground from the two main cutting edges of the milling cutter. Therefore, for the workpiece being processed, the main cutting edge and the micro-toothed blade cannot play a role at the same time, but cut them one after another. In order to ensure that the tool can smoothly play the role of enhanced shearing and cutting, the shape and arrangement of the micro-toothed blade need to be designed.

[0008] In order to ensure that there is no part of the workpiece that cannot be cut during milling, the shape of the micro-tooth needs to be designed to prevent the following situations: Figure 2 The shape of the left-handed micro-toothed blade and the right-handed micro-toothed blade should satisfy the following formula:

[0009]

[0010] Among them, s1 represents the length of the left-handed micro-tooth following edge, s2 represents the length of the right-handed micro-tooth following edge, j represents the width of the left-handed micro-tooth, l represents the width of the right-handed micro-tooth, e1 represents the width of the edgeless zone that may exist when the left-handed micro-tooth following edge 8 is combined with the left-handed main cutting edge 1, and e2 represents the width of the edgeless zone that may exist when the right-handed micro-tooth following edge 7 is combined with the right-handed main cutting edge 2.

[0011] Further deduction yields:

[0012] jcosP3=s1 cosP1 (3)

[0013] lcosP2=s2 cosP4 (4)

[0014] In order to ensure that every point on the workpiece can be cut by the main cutting edge and the micro-tooth slave edge during milling, the arrangement of the micro-tooth needs to be designed, such as Figure 3 As shown. Among them, the position of the micro-tooth and the main cutting edge should satisfy the following formula:

[0015] j i =m1=s (5)

[0016]

[0017] l i =n1=q (8)

[0018]

[0019] Wherein, i represents the i-th cutting edge, n represents the total number of edges, g and f are constants, m represents the distance from the first left-handed micro-tooth to the tip of the left-handed main cutting edge, j represents the width of the left-handed micro-tooth, r represents the spacing of the left-handed micro-tooth, n represents the distance from the first right-handed micro-tooth to the tip of the right-handed main cutting edge, l represents the width of the right-handed micro-tooth, and k represents the spacing of the right-handed micro-tooth.

[0020] The main cutting edge and the micro-toothed secondary edge are spaced apart, and the micro-toothed secondary edges on different cutting edges are spaced apart in the horizontal direction. In this way, when the tool rotates one circle, the material will be cut by the cutting edge and the micro-toothed secondary edge in sequence, ensuring the realization of the enhanced shear cutting function. However, when g>n-1, it can be found that there will be an area covered only by the main cutting edge, and when When the micro-teeth are only covered by the blade, these are the two extreme cases of micro-teeth arrangement. Times the micro-tooth width, no more than n-1 times the micro-tooth width can ensure that every material on the workpiece will be subjected to the effect of enhanced shear cutting.

[0021] The selection of the left-handed main cutting edge helix angle P1 and the right-handed main cutting edge helix angle P2 is related to the chip removal effect of the tool, and should be reasonably selected between 15 and 45°; the selection of the left-handed micro-tooth trailing edge helix angle P3 and the right-handed micro-tooth trailing edge helix angle P4 is related to the shear cutting effect of the tool, and should be reasonably selected between 30 and 90°.

[0022] The width of left-handed micro-tooth and right-handed micro-tooth is related to the chip removal effect of micro-tooth. If the width of micro-tooth is too small, the chip removal space of micro-tooth will be insufficient, which will cause chip adhesion and blockage of micro-tooth and the cutting performance of tool will decrease rapidly. Therefore, the width j of left-handed micro-tooth should be reasonably selected between 0.2 and 4.2 mm, and the width l of right-handed micro-tooth should be reasonably selected between 0.2 and 4.2 mm.

[0023] When the tool rotates, the left-handed main cutting edge and the right-handed main cutting edge successively shear and cut the material on the upper and lower edges of the workpiece in the direction of strong constraint. For materials in a weak constraint state on the surface, there may still be a situation where the material is not effectively removed, and the unremoved material may be extruded and deformed in the direction of the workpiece centerline under the action of the main cutting edge. The back support of the surface material is strengthened due to the extrusion deformation. Then, the left-handed micro-tooth blade and the right-handed micro-tooth blade will further shear and remove the unremoved material in the direction of strong constraint, realizing secondary enhanced shear removal of the material. And because the helix angles of the main cutting edge and the micro-tooth blade are different, the unremoved material will swing back and forth, which is also conducive to the expansion of fatigue cracks of strong and tough thermoplastic resins, and then they are effectively removed, which is conducive to the low-damage milling of thermoplastic composites.

[0024] The beneficial effects of the present invention are as follows: the present invention proposes a main-slave multi-blade staggered tooth tool structure with enhanced shear cutting function. The tool realizes enhanced shear cutting function by opening micro-toothed slave blades with the same spiral direction but different spiral angles on the main cutting edge. Under this function, the material in the weakly constrained state of the surface layer is effectively removed by the shear cutting action of the main cutting edge and the micro-toothed slave blade in the strong constraint direction for multiple times, thereby achieving effective suppression of surface damage. The structure involved in the present invention is simple and easy to manufacture. Its application helps to achieve high-quality and efficient milling processing of thermoplastic composites, and is conducive to promoting the application of thermoplastic composites. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a master-slave multi-edge staggered tooth tool structure.

[0026] Figure 2 Schematic diagram of the specific shape of the micro-tooth on the tool, where (a) is a left-handed micro-tooth blade and (b) is a right-handed micro-tooth blade.

[0027] Figure 3The arrangement and distribution diagram of the micro-teeth on the tool, where (a) is the overall schematic diagram of the tool and (b) is the planar expansion diagram of the tool.

[0028] Figure 4 This is the experimental verification effect of the present invention, wherein (a) is the surface and (b) is the surface layer.

[0029] In the figure: 1 left-handed main cutting edge, 2 right-handed main cutting edge, 3 left-handed main chip groove, 4 right-handed main chip groove, 5 left-handed micro-tooth, 8 left-handed micro-tooth following edge, 6 right-handed micro-tooth, 7 right-handed micro-tooth following edge, P1 left-handed main cutting edge helix angle, P2 right-handed main cutting edge helix angle, P3 left-handed micro-tooth following edge helix angle, P4 right-handed micro-tooth following edge helix angle, m distance between left-handed micro-tooth and tip of left-handed main cutting edge, j width of left-handed micro-tooth, r spacing of left-handed micro-tooth, n distance between right-handed micro-tooth and tip of right-handed main cutting edge, l width of right-handed micro-tooth, k spacing of right-handed micro-tooth. DETAILED DESCRIPTION

[0030] The specific implementation of the master-slave multi-blade staggered tooth structure with enhanced shearing and cutting functions involved in this solution is described below in combination with the accompanying drawings and technical solutions.

[0031] like Figure 1 As shown, the present invention is a main-slave multi-blade staggered tooth tool structure with enhanced shearing and cutting functions, which is mainly characterized by a left-handed main cutting edge 1, a right-handed main cutting edge 2, a left-handed main chip groove 3, and a right-handed main chip groove 4; the improved parts are respectively composed of left-handed micro-teeth 5, right-handed micro-teeth 6, right-handed micro-teeth from the blade 7, and left-handed micro-teeth from the blade 8. The left-handed main cutting edge 1 and the right-handed main cutting edge 2 first shear and cut the materials on the upper and lower edges of the workpiece in the strong constraint direction, and then the left-handed micro-teeth from the blade 8 and the right-handed micro-teeth from the blade 7 further shear and cut the unremoved materials in the strong constraint direction for a second time, thereby realizing multiple enhanced shearing and removal of the materials. And because the helix angles of the main cutting edge and the micro-teeth from the blade are different, the unremoved materials swing up and down, which is conducive to the expansion of fatigue cracks of the material, and helps to remove the tough thermoplastic resin material, thereby effectively suppressing processing damage.

[0032] The resin plasticity of thermoplastic composites is strong and the elongation at break is large, which leads to greater deformation of the workpiece during cutting, making it more difficult to cut the fibers. The uncut thermoplastic resin and fibers combine, and the surface is prone to flaky flash damage. These irreversible damages lead to poor processing quality and seriously affect the assembly accuracy and efficiency of components. However, the processing accuracy requirements for thermoplastic composites in engineering are extremely high. Therefore, in order to verify the milling effect of the present invention, a verification experiment was carried out using carbon fiber reinforced polyetheretherketone-based composites as an example.

[0033] The three-edge main-slave multi-edge staggered tooth milling cutter with a nominal diameter of 10mm was used, among which the helix angle of the left-handed main cutting edge was 25°, the helix angle of the right-handed main cutting edge was 35°, the helix angle of the left-handed micro-tooth was 25°, and the helix angle of the right-handed micro-tooth was 25°. The width of the left-handed micro-tooth was 1.8mm, the width of the right-handed micro-tooth was 1.6mm, and the tool was not coated. The selected material was an 8mm multi-directionally laminated carbon fiber reinforced polyetheretherketone-based composite material plate produced by Jiangsu Junhua Engineering Plastics Products Co., Ltd. The processing parameters were a speed of 4000r / min and a feed of 300mm / min.

[0034] Using the above-mentioned tool, workpiece and milling parameters, dry milling experiments can effectively inhibit milling damage, such as Figure 4 The surface burr length is ≤0.2mm, the surface roughness is ≤3.2μm, and the milling distance is about 2.2m. Compared with ordinary composite milling cutters, this tool has a higher quality maintenance life when milling thermoplastic composites.

Claims

1. A master-slave multi-edge staggered tooth milling tool structure with enhanced shear cutting function, characterized in that: The main-slave multi-edge staggered tooth milling tool structure comprises a main body part and an improved part; the main body part is a staggered tooth tool structure, comprising a left-handed main cutting edge (1), a right-handed main cutting edge (2), a left-handed main chip removal groove (3) and a right-handed main chip removal groove (4); the improved part comprises a left-handed micro-tooth (5), a right-handed micro-tooth (6), a right-handed micro-toothed follower edge (7) and a left-handed micro-toothed follower edge (8); the left-handed micro-tooth (5) is opened in the edge band of the left-handed main cutting edge (1), and the upper edge of the micro-tooth is modified to be a left-handed micro-toothed follower edge (8); the right-handed micro-tooth (6) is opened in the right-handed main cutting edge ( 2), the lower edge of the micro-tooth is modified to a right-handed micro-tooth trailing edge (7), the angle between the left-handed main cutting edge (1) and the milling cutter axis is P1, the angle between the right-handed main cutting edge (2) and the milling cutter axis is P2, the angle between the left-handed micro-tooth trailing edge (8) and the milling cutter axis is P3, and the angle between the right-handed micro-tooth trailing edge (7) and the milling cutter axis is P4; when the tool rotates, the left-handed micro-tooth trailing edge (8) and the left-handed main cutting edge (1) cut alternately, and the right-handed micro-tooth trailing edge (7) and the right-handed main cutting edge (2) cut alternately, thereby generating an enhanced shear cutting effect.

2. The master-slave multi-blade staggered tooth milling tool structure with enhanced shearing and cutting function according to claim 1 is characterized in that: The shapes of the left-handed micro-toothed blade (8) and the right-handed micro-toothed blade (7) should satisfy the following formula: Wherein, s1 represents the length of the left-handed micro-toothed blade (8), s2 represents the length of the right-handed micro-toothed blade (7), j represents the width of the left-handed micro-tooth (5), l represents the width of the right-handed micro-tooth (6), e1 represents the width of the non-edge zone that may exist when the left-handed micro-toothed blade (8) is combined with the left-handed main cutting edge (1), and e2 represents the width of the non-edge zone that may exist when the right-handed micro-toothed blade (7) is combined with the right-handed main cutting edge (2); Further deduction: jcosP3=s1 cosP1 (3) lcosP2=s2 cosP4 (4) In order to ensure that every point on the workpiece can be cut by the main cutting edge and the micro-tooth slave edge during milling, the arrangement of the micro-tooth needs to be designed; the position of the micro-tooth and the main cutting edge should satisfy the following formula: j i =m1=s (5) l i =n1=q (8) Wherein, i represents the i-th cutting edge, n represents the total number of edges, g and f are constants, m represents the distance from the first left-handed micro-tooth trailing edge (8) to the tip of the left-handed main cutting edge (1), j represents the width of the left-handed micro-tooth (5), r represents the spacing of the left-handed micro-tooth (5), n represents the distance from the first right-handed micro-tooth trailing edge (7) to the tip of the right-handed main cutting edge (2), l represents the width of the right-handed micro-tooth (6), and k represents the spacing of the right-handed micro-tooth (6); At the same time, ensure that the spacing between the micro teeth is not less than times the micro-tooth width.

3. The master-slave multi-blade staggered tooth milling tool structure with enhanced shearing and cutting function according to claim 1, characterized in that: The helix angle P1 of the left-handed main cutting edge (1) and the helix angle P2 of the right-handed main cutting edge (2) are selected between 15 and 45 degrees; the helix angle P3 of the left-handed micro-toothed trailing edge (8) and the helix angle P4 of the right-handed micro-toothed trailing edge (7) are selected between 30 and 90 degrees.

4. The master-slave multi-edge staggered tooth milling tool structure with enhanced shearing and cutting function according to claim 1, characterized in that: The width j of the left-handed micro-tooth (5) is selected between 0.2 and 4.2 mm, and the width l of the right-handed micro-tooth (6) is selected between 0.2 and 4.2 mm.

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