A guide milling cutter for ultrasonic vibration helical milling of carbon fiber composite material

Abstract

This invention discloses a guide milling cutter for ultrasonic vibration helical milling of carbon fiber composite materials. The cutter includes a cutting part and a shank. The top of the cutting part is provided with two pairs of cutting edges, each centrally symmetrically distributed. Four left-handed oblique push-type guide grooves are evenly distributed along the axial direction on the outer circumference of the cutting part. The guide grooves are composed of a push surface and a guide surface. A peripheral cutting edge is connected between the guide grooves. The peripheral cutting edge is provided with seven axial ultrasonic machining teeth with equal spacing. The axial ultrasonic machining teeth are composed of a circumferential roughing edge and an axial ultrasonic finishing edge. An ultrasonic chip-removing groove is connected between two teeth. A transition arc structure is provided on the peripheral cutting edge near the shank. This invention helps to avoid the high-speed jet of gas cooling medium directly acting on the cutting area, which would cause secondary damage to the hole wall. It improves the utilization rate of the gas cooling medium and enhances the chip removal performance of the tool. It also better combines with ultrasonic-assisted machining technology to extend tool life and improve the surface quality of the hole.

Description

Technical Field

[0001] This invention relates to the field of cutting tool technology, and specifically to a guide milling cutter for ultrasonic vibration helical milling of carbon fiber composite materials. Background Technology

[0002] Carbon fiber composites are increasingly used in the aerospace field, leading to ever-increasing demands on the quality of connecting holes. However, carbon fiber composites are inherently anisotropic, making them prone to defects such as delamination, tearing, and burrs during processing. This results in rapid tool wear, and due to their poor thermal conductivity, heat dissipation during hole drilling is difficult, leading to temperature concentration in the cutting zone. When the temperature exceeds the glass transition temperature of the resin, the material's mechanical properties degrade significantly, delamination and tearing damage worsen, and the performance of the workpiece is seriously threatened.

[0003] Traditional drilling is the process for drilling holes in carbon fiber composites. During drilling, the chip removal space is small, the axial force is large, cutting heat is difficult to dissipate, tool life is short, and hole accuracy is low. Furthermore, drilling different diameter holes requires changing drill bits, making it difficult to improve drilling efficiency. The emergence of helical milling technology has improved the problems of excessive axial force, difficult chip removal, and low hole-making efficiency during drilling. However, in practical applications, when the tool wears significantly, burrs and tearing defects are prone to occur at the exit point, further reducing tool life. Moreover, the problem of decreased hole quality due to cutting heat accumulation has not been effectively resolved.

[0004] Ultrasonic-assisted machining applies high-frequency vibrations to the cutting tool, creating intermittent high-frequency contact between the tool and the workpiece, thereby reducing net cutting time and increasing tool life. However, the integration of current tool structures with ultrasonic-assisted machining is relatively weak; tool structures cannot fully utilize the advantages of ultrasonic-assisted machining, and there is still room for improvement in tool chip removal performance. Currently, the common design approach is to add internal cooling holes to the tool to mitigate the impact of cutting heat on hole quality. While this effectively reduces the temperature in the cutting zone, the high-speed jet of gas cooling medium can cause strong compression and scratching of the chips on the tool surface, which is detrimental to tool wear suppression and enhances the ejection of material at the exit, exacerbating exit burr defects. Furthermore, some of the gas cooling medium cannot effectively reach the cutting zone.

[0005] Therefore, it is necessary to develop ultrasonic spiral milling cutters made of carbon fiber composite materials. During the hole-making process, the cutter guides the gas cooling medium into the cutting area through its own structure, which can improve the hole-making damage caused by heat accumulation, improve the utilization rate of the cooling medium, and alleviate the impact of the gas cooling medium on the cutting area. At the same time, the cutter structure should be improved to enhance the chip removal capability of the cutter. Furthermore, it should be better combined with ultrasonic-assisted machining technology to improve the hole-making quality and delay tool wear. Summary of the Invention

[0006] The purpose of this invention is to provide a flow-guided end mill for ultrasonic spiral milling of carbon fiber composite materials, in order to solve the problems of heat accumulation during spiral milling, secondary damage to the hole wall caused by the direct action of high-speed jet gas cooling medium on the cutting area, low utilization rate of gas cooling medium, inability of the tool structure to be well integrated with ultrasonic-assisted machining technology, and insufficient chip removal performance of the tool. Therefore, a flow-guided end mill for ultrasonic vibration spiral milling of carbon fiber composite materials is proposed.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A flow-guided end mill for ultrasonic vibration helical milling of carbon fiber composite material includes a cutting part and a shank. The top of the cutting part is provided with two pairs of cutting edges that are centrally symmetrically distributed. Four left-handed inclined flow-guided grooves are evenly distributed along the axial direction on the outer circumference of the cutting part. The flow-guided grooves are composed of a pushing surface and a guiding surface. A peripheral cutting edge is connected between the flow-guided grooves. Seven axial ultrasonic machining teeth with equal spacing are provided on the peripheral cutting edge. The axial ultrasonic machining teeth are composed of a circumferential roughing cutting edge and an axial ultrasonic finishing cutting edge. An ultrasonic chip-breaking groove is connected between the two teeth. A transition arc structure is provided near the shank of the peripheral cutting edge.

[0009] Preferably, the diameter D of the cutting part is 10 mm and the core thickness d is 5 mm;

[0010] Preferably, the diameter of the handle is 8mm;

[0011] Preferably, the inclined push-type guide groove is also a peripheral chip removal groove, the push surface is the front face of the peripheral blade, the guide surface is the back face of the peripheral blade, and the peripheral blade has a left-handed right-cutting structure;

[0012] Preferably, the effective guiding length of the inclined push-type flow guide groove is one-quarter of the tool pitch;

[0013] Preferably, the structural parameters of the inclined push-type flow guide channel are: helix angle β = 45°, effective flow guide length L1 = 8mm, and channel depth h1 = 2.5mm;

[0014] Preferably, the axial ultrasonic finishing cutting edge length L2 is 0.6 mm, and the circumferential roughing cutting edge length L3 is 0.4 mm;

[0015] Preferably, the rake angle γ0 of the axial ultrasonic finishing cutting edge is 5° and the clearance angle α0 is 7°;

[0016] Preferably, the ultrasonic chip-removing groove depth h2 is 0.4 mm, the tilt angle δ is 0°~30°, and the spacing L4 is 0.4 mm;

[0017] Preferably, the radius R of the transition arc structure is 0.8 to 1 mm;

[0018] The advantages of this invention are as follows: The carbon fiber composite spiral milling end mill of this invention avoids the direct action of high-speed jet cooling medium on the cutting area. A dedicated cooling device sprays the cooling medium onto the tool. Through the tool's high-speed rotation and the left-hand and right-hand cutting structure of the peripheral cutting edge, the rake face of the peripheral cutting edge exerts a downward pushing force on the cooling medium, while the flank face of the peripheral cutting edge generates negative pressure to guide the cooling medium into the guide groove, thus achieving a guiding effect. Simultaneously, some of the cooling medium provides a cooling effect for the tool, effectively mitigating the impact of the cooling medium on the cutting area and the difficulty in dissipating cutting heat accumulation. It also improves the utilization rate of the cooling medium and reduces the amount of cooling medium used. Cost reduction and shorter cutting length effectively reduce the dissipation of kinetic energy of the gas cooling medium during the flow process. The flow-guiding arc transition structure near the shank peripheral cutting edge improves the flow-guiding capacity of the flank face. The axial ultrasonic machining tooth structure is better integrated with the ultrasonic-assisted machining method. The axial ultrasonic finishing edge, based on the axial ultrasonic vibration assistance, repeatedly cuts fibers through high-frequency axial vibration, thereby improving the material removal rate of the hole wall surface. Multiple axial ultrasonic machining teeth on the same peripheral cutting edge effectively reduce the peripheral cutting task and extend the tool life. The ultrasonic chip-dispersing groove removes the chips generated by the axial finishing edge, improving the chip removal performance of the tool and enabling the tool to better integrate with ultrasonic-assisted machining technology.

[0019] Figure 1 This is a schematic diagram of the overall structure of the guide milling cutter for ultrasonic spiral milling of carbon fiber composite materials according to the present invention;

[0020] Figure 2 This is a schematic diagram of the flow guide groove structure of the flow guide milling cutter for ultrasonic spiral milling of carbon fiber composite materials according to the present invention;

[0021] Figure 3 It is attached Figure 1 AA cross-section diagram;

[0022] Figure 4 This is a schematic diagram of the axial ultrasonic machining tooth structure of the guide milling cutter for ultrasonic spiral milling of carbon fiber composite materials according to the present invention;

[0023] Figure 5 This is a three-dimensional view of the ultrasonic chip-breaking groove of the ultrasonic spiral milling cutter for carbon fiber composite materials of the present invention;

[0024] Figure 6 This is a plan view of the ultrasonic chip-breaking groove of the ultrasonic spiral milling cutter for carbon fiber composite materials according to the present invention;

[0025] In the figure: 1. Cutting part; 2. End edge; 3. End tooth chip groove; 4. Circumferential edge; 5. Inclined push-type guide groove; 6. Ultrasonic chip-breaking groove; 7. Axial ultrasonic machining tooth; 8. Transition arc structure; 9. Shank; 51. Flow-pushing surface; 52. Flow-guiding surface; 71. Circumferential roughing edge; 72. Axial ultrasonic finishing edge; 721. Axial ultrasonic finishing edge rake face; 722. Axial ultrasonic finishing edge flank face. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Specific implementation case 1: such as Figures 1-4 As shown, this invention provides a carbon fiber composite spiral milling end mill, which consists of a cutting part 1 and a shank 9. The cutting part has a diameter of 10 mm and a core thickness d of 5 mm, while the shank 9 has a diameter of 8 mm. The cutting part consists of an end cutting edge 2, an end tooth chip groove 3, a peripheral cutting edge 4, a slanted push-type flow guide groove 5, an axial ultrasonic machining tooth 7, an ultrasonic chip-breaking groove 6, and a transition arc structure 8. The end cutting edge 2 consists of two pairs of centrally symmetrical cutting edges. The outer circumferential surface of the cutting part 1 is evenly provided with four left-handed slanted push-type flow guide grooves 5, each consisting of a push surface 51 and a guide surface 52. The four peripheral cutting edges... 4. The cutting edge 1 is evenly distributed around the circumference and has a left-handed right-cutting structure. Seven axial ultrasonic machining teeth 7 are evenly arranged on the circumferential cutting edge 4. The axial ultrasonic machining teeth 7 are composed of a circumferential roughing cutting edge 71 and an axial ultrasonic finishing cutting edge 72. The axial ultrasonic finishing cutting edge 72 has a rake angle γ0 of 5°, a clearance angle α0 of 7°, and a length L2 of 0.6 mm. The circumferential roughing cutting edge 71 has a length L3 of 0.4 mm. An ultrasonic chip-breaking groove 6 is provided between the two teeth, with a depth h2 of 0.4 mm and a spacing L4 of 0.4 mm. A transition arc structure 8 is provided near the shank of the circumferential cutting edge, with an arc radius R of 0.8 to 1 mm.

[0028] Specific Implementation Case Two: For example Figures 2-3As shown, the inclined push-type guide groove 5 is also a peripheral chip removal groove. The push surface 51 is the peripheral rake face, and the guide surface 52 is the peripheral flank face. During the helical milling process, a special cooling device sprays gas cooling medium onto the tool. Due to the high-speed rotation of the tool, the peripheral rake face has a downward pushing effect on the gas cooling medium, and the peripheral flank face generates a negative pressure to guide the gas cooling medium into the guide groove 5. This achieves the goal of guiding the gas cooling medium to the cutting area, mitigating the impact of the gas cooling medium on the cutting area. In addition, some of the gas cooling medium provides a cooling effect on the tool surface, thereby improving the utilization rate of the cooling medium. The tool guiding gain effect is closely related to the effective guiding length, helix angle, and groove depth of the guide groove 5. The effective guiding length has a significant impact on the push surface 51 and the guide surface 52. The effective guiding area of ​​the flow surface 52 has a direct impact. The length selection needs to consider the kinetic energy dissipation of the gas cooling medium during the guiding process. The effective guiding length is one-quarter of the tool pitch. The effective guiding length L1 of the inclined push-type guide groove 5 is 8mm. The helix angle affects the guiding direction. Under the premise of ensuring the cutting performance of the tool, appropriately increasing the helix angle is more conducive to the gas cooling medium entering the cutting area. The helix angle β of the inclined push-type guide groove 5 is 45°. The groove depth is related to the volume of the guide groove 5. Under the premise of ensuring the rigidity of the tool, increasing the groove depth can effectively improve the tool guiding effect. The groove depth h2 of the inclined push-type guide groove 5 is 2.5mm. The arc surface of the transition arc structure 8 reduces the interference on the guiding of the push surface 51 and is more conducive to the gas cooling medium entering the guide groove 5.

[0029] Specific Implementation Case 3: As shown in the spiral milling process, the circumferential roughing edge 71 of the axial ultrasonic machining tooth 7 structure completes the task of removing part of the material from the hole wall. The axial ultrasonic finishing edge 72 repeatedly cuts the fiber under high-frequency axial vibration to complete the finishing task of the hole wall. By setting the rake face 721 and the flank face 722 of the axial ultrasonic finishing edge 72, the chip-cutting performance of the axial ultrasonic machining tooth 7 is improved and the wear of the cutting edge is reduced. An ultrasonic chip-dispersing groove 6 is provided between the axial ultrasonic machining teeth 7 to control the discharge of chips processed by the axial ultrasonic finishing edge 72, improve the chip removal capability of the tool, and at the same time play a role in suppressing burrs, thus better combining ultrasonic-assisted machining technology.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flow-guided end mill for ultrasonic helical milling of carbon fiber composite materials, characterized in that: The cutting part (1) of the tool has four left-handed oblique push-type guide grooves (5) evenly distributed on the outer circumferential surface. The guide grooves (5) are composed of a push surface (51) and a guide surface (52). A peripheral cutting edge (4) is connected between adjacent guide grooves (5). Seven axial ultrasonic machining teeth (7) with the same spacing are provided on the peripheral cutting edge. The axial ultrasonic machining teeth are composed of a circumferential roughing cutting edge (71) and an axial ultrasonic finishing cutting edge (72). An ultrasonic chip-breaking groove (6) is connected between the two teeth. A transition arc structure (8) is provided near the shank of the peripheral cutting edge. The structural parameters of the inclined push-type flow guide groove (5) are: helix angle 45°, groove depth h1 2.5mm, and effective flow guide length L1 8mm; The axial ultrasonic finishing blade (72) has a length L2 of 0.6 mm, a front angle γ0 of 5°, a rear angle α0 of 7°, and a circumferential roughing blade (71) with a length L3 of 0.4 mm. The ultrasonic chip separator (6) has an inclination angle δ of 0° to 30°, a groove depth h2 of 0.4 mm, and a spacing L4 of 0.4 mm.

2. The flow-guided end mill for ultrasonic helical milling of carbon fiber composite materials according to claim 1, characterized in that: The inclined push-type guide groove is also a peripheral chip removal groove, with the pushing surface being the front face of the peripheral blade and the guiding surface being the rear face of the peripheral blade.

3. The flow-guided end mill for ultrasonic helical milling of carbon fiber composite materials according to claim 1, characterized in that: The effective guiding length of the inclined push-type guide groove is one-quarter of the tool pitch.

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