A left and right hand cutter structure with bidirectional alternate cutting function

Abstract

The present application belongs to the technical field of drilling tools in mechanical processing, and discloses a left-right rotary cutter structure with bidirectional alternating cutting function, which is mainly composed of a first step, a left rotary cutting edge, a chip flute, a main cutting edge, a right rotary cutting edge, a left rotary tool face, a left rotary upper blade and a cutting edge. The structure modifies the traditional right rotary cutting edge and the main cutting edge into the left rotary cutting edge and the left rotary tool face, and plays a cutting role together with the original cutting edge. When the main shaft rotates, the bidirectional alternating cutting function is generated, the alternating cutting makes the fatigue crack of the material expand, and then the effective cutting of the burr composed of high-hardness fiber and high-toughness resin is realized, and the low-damage processing of the material is realized. The application of the present application is helpful to greatly improve the low-damage hole making efficiency of thermoplastic composites, reduce the processing cost, and has good engineering application prospect.

Description

Technical Field

[0001] This invention belongs to the field of drilling tool technology in machining, and relates to a left-hand rotary cutting tool structure with bidirectional alternating cutting function. Background Technology

[0002] To meet the performance demands of next-generation high-end equipment, high-performance carbon fiber reinforced thermoplastic resin matrix composites (hereinafter referred to as "thermoplastic composites") have attracted widespread attention from the international manufacturing industry. Components made of this material often require drilling to meet the connection requirements during assembly. However, the material at the drill exit point of thermoplastic composites is weakly constrained, and the fibers are easily affected by the axial force of the cutting tool during machining, causing out-of-plane deformation and tool deflection, making effective cutting difficult and resulting in burrs and other damage. Furthermore, the high toughness of thermoplastic resin makes it more prone to out-of-plane deformation under the axial force of the cutting tool without fracture, combining with uncut fibers to cause sheet-like burr damage. This damage severely affects the accuracy and efficiency of assembly, restricting the application of thermoplastic composites.

[0003] As a newly emerging high-performance composite material, research on the processing of thermoplastic composites is extremely limited. These materials are composed of a mixture of fibers and resins, exhibiting anisotropic and heterogeneous characteristics. Simultaneously, the high toughness of thermoplastic resins leads to greater ductility. Their cutting process differs significantly from that of traditional homogeneous metals and thermoset composites. However, current tool designs are mostly geared towards metals and thermoset composites; continuing to use tool structures designed for these materials makes it difficult to effectively suppress processing damage in thermoplastic composites. For example, Zhen Yu et al., in their paper titled "Drill bit with a helical groove edge for clean drilling of carbon fiber reinforced plastic" published in the Journal of Materials Processing Tech., Issue 274, proposed a novel tool structure with a helical groove edge, which can effectively reduce processing damage through the additional cutting action of the helical groove edge. Furthermore, Zhou Ruihua and Jiang Feng of Suzhou Fleck Precision Tools Co., Ltd. disclosed a drill bit for drilling aerospace materials and its mounting structure, patent application number 202211507713.8. The reverse groove effectively suppresses burrs during machining of thermosetting composites. However, this type of tool structure does not require consideration of resin toughness during design, and therefore cannot effectively address the problem of difficult-to-cut tough resins, making it difficult to meet the high-quality machining requirements of thermoplastic composites. Therefore, there is an urgent need to develop new tool structures and specialized tools for thermoplastic composites to meet the demands of high-quality drilling machining. Summary of the Invention

[0004] This invention addresses the problem of flaky burrs easily appearing at the exit of thermoplastic composite drilling under axial force. It proposes a left- and right-handed cutting tool structure with bidirectional alternating cutting function. Specifically, one of the two right-handed cutting edges is modified to left-handed, and a new cutting edge is ground onto the left-handed structure. This new edge, together with the original cutting edge, performs the cutting action, generating a bidirectional alternating cutting function as the spindle rotates. To ensure this alternating cutting function, the height of the left and right-handed cutting edges is adjusted. The alternating cutting causes fatigue cracks in the material to propagate, effectively removing the weakly constrained high-hardness fibers and high-toughness resin at the exit, thereby effectively suppressing flaky burrs at the exit of thermoplastic composite drilling.

[0005] The technical solution of the present invention:

[0006] A bidirectional alternating cutting tool structure includes a stepped drill portion, consisting of a first step 1, a chip flute 3, a main cutting edge 4, and a right-hand cutting edge 5. The improved portion consists of a left-hand cutting edge 2, a left-hand tool face 6, a left-hand cutting edge band 7, and a cutting edge 9. A portion of the original right-hand cutting edge 5 is modified into a left-hand cutting edge 2, forming the left-hand tool face 6, which intersects with the chip flute 3 to form the cutting edge 9. The left-hand cutting edge 2 and the right-hand cutting edge 5 generate a bidirectional alternating cutting function when the spindle rotates.

[0007] The left-hand cutting edge 2 and the left-hand cutting face 6 are obtained by grinding the chip removal groove 3 on the drill bit. During this process, the height difference between the lowest point of the left-hand cutting edge 2 and the lowest point of the right-hand cutting edge 5 is controlled to be m. The relationship between the height difference m between the left-hand cutting edge 2 and the right-hand cutting edge 5 along the tool axis 8 and f satisfies the following formula:

[0008]

[0009] In the formula, v represents the spindle speed, f represents the feed rate per revolution, and D represents the tool diameter.

[0010] The feed rate during one revolution of the tool at speed v must be less than half the height difference m. This means that the left-hand cutting edge must engage first within a certain rotational period, and the right-hand cutting edge only begins to engage after a certain time.

[0011] The angle between the left-hand cutting edge 2 and the tool axis is P1, and the angle range of P1 is 0° to 50°. This angle is related to whether the chips can be effectively discharged and needs to be selected appropriately.

[0012] The width n of the left-hand cutting edge is obtained by adjusting the back of the cutting edge along the upper cutting edge band 7. This width is related to the amount of frictional heat generated. Overheating will affect the resin's constraint on the fibers. The width range is 0.8 mm to 2 mm. To ensure the cutting action of the right-hand cutting edge, the apex angle of the main cutting edge 4 needs to be ground. The angle P2 formed by the main cutting edge 4 and the tool axis ranges from 55° to 125°.

[0013] After the first step 1 removes the material, as drilling continues, the left-hand cutting edge 2 first cuts the material, and the resulting chips are discharged along the left-hand cutting face 6 and then along the chip groove 3. Under the action of the left-hand cutting edge 2 and the left-hand cutting face 6, the material deflects downwards at a certain angle. Further, the main cutting edge 4 and the right-hand cutting edge 5 begin to function, removing the deflected material. For materials with weak exit constraints, the main cutting edge 4 cannot effectively remove the material, and the right-hand cutting edge 5 will play a greater role in material removal. Once the right-hand cutting edge 5 cannot effectively cut the material, the alternating cutting function generated by the left and right helical structures allows for the effective removal of tough materials, ensuring low-damage machining.

[0014] The beneficial effects of this invention are as follows: This invention proposes a left- and right-handed rotary cutting tool structure with bidirectional alternating cutting function. This structure achieves alternating cutting function by changing the arrangement direction of the cutting edge bands. Under this function, fatigue cracks in the exit tough material propagate, thereby achieving secondary effective removal of the remaining tough material at the exit. The structure involved in this invention is simple and easy to manufacture. Its application helps improve the hole-making efficiency of thermoplastic composites, thereby promoting the application of thermoplastic composite materials. Attached Figure Description

[0015] Figure 1 This is a stepped left and right rotating blade tool structure, where (a) is the left view and (b) is the right view.

[0016] Figure 2 This is a diagram showing the experimental verification results of the present invention.

[0017] In the diagram: 1 First step, 2 Left-hand cutting edge, 3 Chip groove, 4 Main cutting edge, 5 Right-hand cutting edge (cutting band), 6 Left-hand tool face, 7 Left-hand cutting edge upper cutting band, 8 Tool axis, 9 Cutting edge. P1 Left-hand cutting edge angle, P2 Main cutting edge angle, m Height difference between left-hand and right-hand cutting edges, n Left-hand cutting edge band width. Detailed Implementation

[0018] The following description, in conjunction with the accompanying drawings and technical solutions, details specific embodiments of the left-right rotating structure with bidirectional alternating cutting function involved in this invention.

[0019] like Figure 1As shown, this invention is a left-hand and right-hand cutting tool structure with bidirectional alternating cutting function. Its main features include a first step 1, a left-hand cutting edge 2, a chip groove 3, a main cutting edge 4, a right-hand cutting edge 5, a left-hand cutting face 6, and a left-hand cutting edge band 7. The left-hand cutting edge 2 and the right-hand cutting edge 5 are primarily responsible for secondary cutting of material that has not been effectively removed. A portion of the original right-hand cutting edge 5 is modified into a left-hand cutting edge 2, which works together with the original cutting edge band to perform the cutting action. During spindle rotation, a bidirectional alternating cutting function is generated. The alternating cutting causes fatigue cracks in the material to propagate, thereby achieving effective cutting of tough materials and reducing machining damage.

[0020] Thermoplastic composites are anisotropic and heterogeneous, making them prone to damage during processing. They also possess high toughness, making them susceptible to deformation and difficult to cut, leading to even more severe damage and significantly impacting component assembly and service performance. Therefore, the processing quality requirements for thermoplastic composites are extremely stringent. This invention uses a high-performance polyetheretherketone (PEEK)-based thermoplastic composite as an example to verify the drilling performance of this invention.

[0021] The cutting tool used was a step drill with a nominal diameter of 10 mm, where the first step diameter was 7 mm and it was uncoated. The material being cut was an 8 mm thick multi-directional carbon fiber reinforced polyetheretherketone (PEEK) composite material plate. The spindle speed was selected as 3000 r / min, and the feed rate was selected as 100 mm / min.

[0022] The left-hand cutting edge 2 and the left-hand cutting face 6 are obtained by grinding one of the chip removal grooves 3 on the basis of a stepped drill. The angle P1 between the left-hand cutting edge 2 and the tool axis 8 is 33°. The height difference m between the left-hand cutting edge 2 and the right-hand cutting edge 5 is 1mm.

[0023] The width n of the left-hand cutting edge is 2mm by adjusting the back of the cutting edge along the upper cutting edge band 7. The angle P2 between the main cutting edge 4 and the tool axis is ground to 95°.

[0024] Using the aforementioned cutting tools, workpieces, and machining parameters, continuous drilling experiments were conducted, resulting in the continuous low-damage drilling of over 35 holes. Figure 2 Among them, the layering factor is ≤0.12, and the burr area is ≤0.5mm. 2 This significantly improves the service life of the cutting tools.

Claims

1. A left and right-hand cutter structure having a bidirectional alternate cutting function, characterized by, The left and right rotary cutter structure with bidirectional alternate cutting function is mainly composed of a first step (1), a left rotary cutting edge (2), a chip flute (3), a main cutting edge (4), a right rotary cutting edge (5), a left rotary tool face (6), a left rotary upper edge band (7) and a cutting edge (9); Part of the original right rotary cutting edge (5) is modified into the left rotary cutting edge (2) and the left rotary tool face (6) is formed, the left rotary tool face (6) intersects with the chip flute (3) to form the cutting edge (9); the left rotary cutting edge (2) and the right rotary cutting edge (5) produce bidirectional alternate cutting function when the main shaft rotates; The left rotary cutting edge (2) and the left rotary tool face (6) are obtained by grinding the chip flute (3) on the drill bit, the height difference between the lowest point of the left rotary cutting edge (2) and the lowest point of the right rotary cutting edge (5) is m; the relationship between the height difference m and f of the left rotary cutting edge (2) and the right rotary cutting edge (5) along the tool axis (8) direction satisfies the following formula: In the formula, v represents the main shaft speed, f represents the feed speed per revolution, and D represents the tool diameter; The angle between the left rotary cutting edge (2) and the tool axis (8) is P1, and the angle range of P1 is 0°-50°; The left rotary edge width n is obtained by grinding the back part along the left rotary upper edge band (7), and the range of the left rotary edge width n is 0.8mm-2mm; In order to ensure the cutting effect of the right rotary edge, the top angle of the main cutting edge (4) needs to be ground, the angle between the main cutting edge (4) and the tool axis is P2, and the angle range of P2 is 55°-125°.

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