Thread milling cutter and method of manufacturing the same

Abstract

The application belongs to the technical field of tool machining, and discloses a thread milling cutter and a manufacturing method thereof. The thread milling cutter comprises a cutter body and a cutter grain, the cutter grain is fixedly connected to the cutter body, the cutter grain comprises a body and a plurality of blade parts connected to the body, the plurality of blade parts are arranged at intervals along the circumference of the body, two adjacent blade parts among the plurality of blade parts have a chip groove, the projections of the plurality of chip grooves along the axis of the cutter body are all in the shape of a sector, and the projections of the plurality of chip grooves along the axis of the cutter body have different central angles. The thread milling cutter and the manufacturing method thereof can improve the service life of the cutter, avoid the collapse of the thread tooth profile or the generation of burrs during thread machining, and improve the qualified rate of finished products in thread machining.

Description

Technical Field

[0001] This invention relates to the field of cutting tool technology, and in particular to a thread milling cutter and its manufacturing method. Background Technology

[0002] Thread milling cutters are specialized milling tools adapted to the three-axis linkage system of CNC machining centers for precision thread forming. Unlike traditional tapping methods, they utilize the helical interpolation milling principle to efficiently machine internal and external threads. They are widely used in high-precision thread machining applications such as precision machinery, aerospace, and mold manufacturing. Thread milling cutters offer advantages such as low cutting force, high thread accuracy, strong versatility, and no risk of tool breakage. They are suitable for complex thread machining conditions including high-hardness materials, blind holes, and large diameter holes, gradually replacing traditional tapping processes and becoming the core tool for precision thread machining. Traditional thread end mills are composed of a ductile aluminum matrix and high-hardness SiC ceramic particles. On the one hand, the hardness of SiC particles is above HV2200. During intermittent cutting of small threads, the impact force can easily cause micro-chipping of the tool tip and tooth breakage, and the tap is very likely to break inside the pilot hole. On the other hand, due to the high cutting temperature, the ductile aluminum matrix partially melts, causing milling debris to easily adhere to the thread end mill, forming built-up edge and scratching the thread surface. Furthermore, the high brittleness of the SiC ceramic particles makes them prone to peeling off during cutting and compression, resulting in a poorly finished thread surface. The appearance of pits and holes on the surface; stress concentration at the thread inlet and outlet positions, which can easily cause chipping at the hole opening and missing material in the thread profile, affecting the quality of thread machining. At the same time, since the thermal expansion coefficient of composite materials is between that of aluminum and ceramics, the temperature rise during cutting can cause slight deformation of the workpiece. After cooling, the thread pitch diameter and thread profile dimensions drift. In addition, the material composition inside the composite material is uneven, with varying SiC content in some areas, which causes the cutting resistance of the thread milling cutter to fluctuate. This can easily lead to fluctuations in machine tool load, pitch error, and taper deviation during thread machining, affecting the accuracy and quality of thread machining.

[0003] Therefore, some thread end mills in related technologies are made of PCD (Polycrystalline Diamond). However, due to the uniform distribution of the cutting edges of these thread end mills, a relatively large cutting edge thickness is usually maintained to ensure the overall wear resistance and extend the service life of the tool. This results in insufficient cutting edge sharpness, making it easy for burrs, chipping, and poor surface finish to form on the thread edges during machining. This requires additional grinding, significantly reducing machining efficiency and thread forming accuracy. If the cutting edge structure is thinned to improve the sharpness and eliminate burrs, the structural strength and wear resistance of the PCD cutting edge will be directly weakened. During continuous cutting, the tool is prone to edge wear, chipping, and accelerated dulling, significantly shortening the tool life, increasing the frequency of replacement, and increasing machining production costs and equipment downtime. Summary of the Invention

[0004] The purpose of this invention is to provide a thread milling cutter and its manufacturing method, which can improve the service life of the tool, avoid chipping or burr formation of the thread profile during thread processing, and improve the finished product qualification rate of thread processing.

[0005] To achieve this objective, the present invention adopts the following technical solution: On one hand, a thread milling cutter is provided, including a cutter body and a cutting insert. The cutting insert is fixedly connected to the cutter body. The cutting insert includes a body and a plurality of cutting edges connected to the body. The plurality of cutting edges are spaced apart circumferentially along the body. A chip removal groove is provided between two adjacent cutting edges. The orthographic projection of the plurality of chip removal grooves along the axial direction of the cutter body is fan-shaped, and the projection of the plurality of chip removal grooves along the axial direction of the cutter body has a central angle with different angles.

[0006] Preferably, the cutting edge includes a first cutting face, a second cutting face, and a third cutting face. The first cutting face extends from the end face of the body towards the blade body and is set at an angle to the end face of the body. The second and third cutting faces are set on opposite sides of the first cutting face along a direction perpendicular to the axis of the blade body, and both the second and third cutting faces intersect the first cutting face at an angle. A chip removal groove is formed between the second cutting face of one cutting edge and the third cutting face of the other cutting edge in two adjacent cutting edges.

[0007] Preferably, the second cutting surface includes a first inclined portion and a second inclined portion that intersect at an angle, and the third cutting surface includes a third inclined portion and a fourth inclined portion that intersect at an angle. The first inclined portion intersects the first cutting surface at an angle, the second inclined portion intersects the fourth inclined portion of the adjacent cutting edge at an angle, the third inclined portion intersects the first cutting surface at an angle, and the fourth inclined portion intersects the second inclined portion of the adjacent cutting edge at an angle.

[0008] Preferably, the orthographic projection of the third inclined portion along the axial direction of the cutter body forms a radial rake angle with the radial direction of the cutter body, and the angle of the radial rake angle is -10° to 10°.

[0009] Preferably, the orthographic projection of the fourth inclined portion along the radial direction of the cutter body forms an axial front angle with the axial direction of the cutter body, and the angle of the axial front angle is 5°~10°.

[0010] Preferably, the central angle of the orthographic projection of the chip removal groove along the axial direction of the tool body is 45°~135°.

[0011] Preferably, the blade body includes a shank and a blade head arranged coaxially, one end of the blade head is connected to the shank, the other end of the blade head is connected to the insert, and the diameter of the blade head is smaller than the diameter of the shank.

[0012] Preferably, the total runout tolerance of the multiple cutting edges is less than 0.003 mm.

[0013] Preferably, the cutter body is an alloy cutter body; and / or, the cutting edge is a PCD cutting edge.

[0014] On the other hand, a method for manufacturing a thread end mill is provided, for manufacturing the thread end mill of the above-mentioned technical solution, the method for manufacturing the thread end mill includes the following steps: Welding PCD raw materials to alloy bars; Simultaneously grinding PCD raw materials and alloy bars, we obtain tool blanks and tool body blanks. The cylindricity and total runout of the tool body blanks are both less than 0.0015 mm. Machining the rough blank of the tool body to form the tool holder and the tool head; The rough blank is machined to form the body, cutting edge and chip removal groove.

[0015] The beneficial effects of this invention are as follows: A thread milling cutter and its manufacturing method are provided. This thread milling cutter, by incorporating multiple chip removal grooves, allows for the rapid and smooth discharge of chips generated during cutting, preventing chip accumulation and damage to the machined thread profile. By designing multiple chip removal grooves with fan-shaped axial projections along the cutter body, and each groove having a different central angle θ, an unequally divided groove structure is formed. This results in a non-fixed equidistant periodic spacing between the multiple cutting edges, breaking the inherent excitation frequency of the tool and workpiece system during milling. This effectively suppresses cutting resonance, preventing edge impact damage, abnormally rapid wear, and thread surface vibration defects caused by resonance. This allows the tool to maintain a stable cutting state over a long period, improving thread machining quality and the service life of the thread milling cutter. Attached Figure Description

[0016] Figure 1 This is an isometric view of the thread milling cutter provided by the present invention; Figure 2 This is a first-view schematic diagram of the thread milling cutter provided by the present invention; Figure 3 This is a second-view schematic diagram of the thread milling cutter provided by the present invention; Figure 4 yes Figure 1 A magnified view of part A in the middle; Figure 5 yes Figure 3 A magnified view of part B in the middle section.

[0017] In the picture: 1. Blade body; 11. Handle; 12. Blade tip; 2. Cutting insert; 21. Body; 22. Cutting edge; 221. First cutting face; 222. Second cutting face; 2221. First inclined portion; 2222. Second inclined portion; 223. Third cutting face; 2231. Third inclined portion; 2232. Fourth inclined portion; 23. Chip removal groove. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0019] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0021] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0022] On the one hand, please refer to Figures 1 to 5 A thread milling cutter is provided, including a cutter body 1 and a cutting insert 2. The cutting insert 2 is fixedly connected to the cutter body 1. The cutting insert 2 includes a body 21 and a plurality of cutting edges 22 connected to the body 21. The plurality of cutting edges 22 are arranged at intervals along the circumference of the body 21. A chip removal groove 23 is provided between two adjacent cutting edges 22. The axial projection of the plurality of chip removal grooves 23 along the cutter body 21 is fan-shaped, and the axial projection of the plurality of chip removal grooves 23 along the cutter body 21 has a central angle with different angles.

[0023] Understandably, in a plane perpendicular to the axis of the cutter body 21, the orthographic projection of the chip removal groove 23 is the groove projection; the boundary lines of the groove projection on both sides of the cutter body 1 are the projection boundary lines, and the aforementioned central angle refers to the angle between the two projection boundary lines of the groove projection.

[0024] This design, with multiple chip removal grooves 23, allows for the rapid and smooth discharge of chips generated during cutting, preventing chip accumulation and damage to the machined thread profile. By setting multiple chip removal grooves 23 in a fan shape along the axial projection of the cutter body 21, and by creating unequally divided groove structures with different central angles θ, the circumferential spacing of the multiple cutting edges 22 is not fixed and equidistant. This breaks the inherent excitation frequency of the tool and workpiece system during milling, effectively suppressing cutting resonance and preventing edge impact damage, abnormally rapid wear, and thread surface vibration defects caused by resonance. This ensures the tool maintains a stable cutting state over a long period, improving thread machining quality and extending the lifespan of the thread milling cutter.

[0025] Preferably, the central angle of the chip removal groove 23 projected along the axial direction of the cutter body 21 is 45°~135°. This setting ensures both the rigidity of the thread milling cutter and the chip removal effect.

[0026] Specifically, in this embodiment, the thread milling cutter's insert 2 includes four cutting edges 22, and four chip removal grooves 23 are formed between the four cutting edges 22. The central angles of the four chip removal grooves 23 projected along the axial direction of the cutter body 21 are θ1, θ2, θ3 and θ4, respectively.

[0027] The different angles of θ1, θ2, θ3 and θ4 result in the circumferential spacing of the multiple cutting edges 22 having no fixed equidistant period. This can break the inherent excitation frequency of the tool and workpiece system during milling, effectively suppress cutting resonance, avoid the impact damage, abnormal rapid wear and thread surface vibration defects caused by resonance, and keep the tool in a stable cutting state for a long time, thereby improving the quality of thread processing and the service life of the thread milling cutter.

[0028] Alternatively, please refer to Figure 4The cutting edge 22 includes a first cutting face 221, a second cutting face 222, and a third cutting face 223. The first cutting face 221 extends from the end face of the body 21 toward the blade body 1 and is set at an angle to the end face of the body 21. The second cutting face 222 and the third cutting face 223 are set on opposite sides of the first cutting face 221 along a direction perpendicular to the axis of the blade body 1, and both the second cutting face 222 and the third cutting face 223 intersect the first cutting face 221 at an angle. A chip removal groove 23 is formed between the second cutting face 222 of one cutting edge 22 and the third cutting face 223 of the other cutting edge 22. This configuration, with the first cutting face 221, the second cutting face 222, and the third cutting face 223 forming a cutting wedge structure, combined with the unequally divided chip removal grooves 23, can effectively suppress cutting resonance while ensuring that the edge of some cutting sections 22 has high sharpness for fine finishing, deburring, and improving thread finish. This avoids edge impact damage, abnormally rapid wear, and thread surface vibration defects caused by resonance, improves the overall rigidity and structural stability of the cutting section 22, enhances the thread forming accuracy and surface finish of the thread milling cutter, and extends its service life.

[0029] Optionally, the second cutting face 222 includes a first inclined portion 2221 and a second inclined portion 2222 intersecting at an angle, and the third cutting face 223 includes a third inclined portion 2231 and a fourth inclined portion 2232 intersecting at an angle. The first inclined portion 2221 intersects the first cutting face 221 at an angle, the second inclined portion 2222 intersects the fourth inclined portion 2232 of the adjacent cutting edge 22 at an angle, the third inclined portion 2231 intersects the first cutting face 221 at an angle, and the fourth inclined portion 2232 intersects the second inclined portion 2222 of the adjacent cutting edge 22 at an angle. With this configuration, by providing the first inclined portion 2221 and the second inclined portion 2222 intersecting at an angle on the second cutting face 222, and the third inclined portion 2231 and the fourth inclined portion 2232 intersecting at an angle on the third cutting face 223, graded optimization of the cutting angle is achieved. The first inclined portion 2221 and the third inclined portion 2231 are respectively angled with the first cutting face 221, which can precisely shape the cutting wedge angle of the tip of the cutting edge 22, making the tip of the cutting edge 22 sharper. During the cutting process, the workpiece material is quickly cut off by shearing, avoiding plastic extrusion tearing, suppressing the generation of burrs on the thread flank and crest, and improving the surface finish and forming accuracy of the thread. At the same time, the second cutting face 222 and the third cutting face 223 have a folded structure, which disperses the cutting stress layer by layer, avoiding local stress concentration at the cutting edge. While ensuring high sharpness, it also improves the structural strength of the cutting edge 22, prevents chipping of the cutting edge 22, and increases the service life of the thread milling cutter.

[0030] Alternatively, please refer to Figure 2 The projection of the third inclined portion 2231 along the axial direction of the cutter body 21 forms a radial rake angle with the radial direction of the cutter body 21 (e.g., Figure 2(As shown in the γ angle), the radial rake angle is -10° to 10°. This setting limits the radial rake angle to between -10° and 10°, achieving a balance between cutting edge sharpness and structural strength. If the rake angle is greater than 10°, the cutting edge wedge angle is too small. Although the cutting is sharp, the cutting edge support is weak, making it prone to chipping and tooth breakage during machining. If the rake angle is less than -10°, the cutting edge wedge angle is too large, increasing cutting resistance, making it prone to vibration, causing chatter marks on the workpiece threads, and also compressing the material to form burrs.

[0031] Alternatively, please refer to Figure 5 The projection of the fourth inclined portion 2232 along the radial direction of the cutter body 21 forms an axial rake angle with the axial direction of the cutter body 21 (e.g., Figure 5 As shown by angle α), the axial rake angle is 5°~10°. This setting, with the axial rake angle formed by the fourth inclined portion 2232 between 5° and 10°, improves the edge sharpness, reduces cutting resistance, and allows for shearing action during cutting to separate the workpiece material, reducing thread burrs caused by material extrusion and tearing, and improving the surface finish. It avoids the problems of excessively small axial rake angle leading to increased cutting resistance, burr formation due to workpiece extrusion, or increased machining load causing tool vibration; and also avoids the problems of insufficient cutting edge support thickness due to excessively large axial rake angle, which can easily lead to edge chipping and accelerated wear under cutting impact.

[0032] Alternatively, please refer to Figure 1 and Figure 3 The tool body 1 includes a tool holder 11 and a tool head 12 coaxially arranged. One end of the tool head 12 is connected to the tool holder 11, and the other end of the tool head 12 is connected to the insert 2. The diameter of the tool head 12 is smaller than the diameter of the tool holder 11. With this arrangement, when machining threads, the small-diameter tool head 12 can extend into the workpiece machining area, effectively avoiding interference structures such as workpiece sidewalls and steps, and preventing the tool from rubbing and colliding with the workpiece. At the same time, the larger diameter of the rear tool holder 11 ensures overall rigidity, strong resistance to bending and impact during the cutting process, less likelihood of tool vibration, and higher dimensional accuracy in thread machining.

[0033] Optionally, the total runout tolerance of the multiple cutting edges 22 is less than 0.003 mm. Further, the thread profile accuracy of the multiple cutting edges 22 is less than 0.005 mm. This configuration ensures that the thread end mill achieves high-speed, high-precision, and long-life milling operations.

[0034] Optionally, the blade body 1 is an alloy blade body. Preferably, the blade body 1 can be made of materials such as cemented carbide, high-speed steel, and die steel.

[0035] Optionally, the cutting insert 2 is a PCD cutting insert. This configuration leverages the high hardness and excellent wear resistance of PCD cutting inserts. Using PCD cutting inserts results in a slower rate of edge dulling during long-term milling operations, extending the lifespan of the thread end mill, reducing downtime for tool changes, and lowering machining costs.

[0036] On the other hand, this embodiment provides a method for manufacturing a thread end mill, used to manufacture the thread end mill of the above-mentioned technical solution. The method for manufacturing the thread end mill includes the following steps: S1. Weld the PCD raw material to the alloy bar.

[0037] Specifically, the PCD raw material and the alloy bar are welded using vacuum welding technology to improve the connection strength between the PCD raw material and the alloy bar.

[0038] Preferably, the alloy bar stock can be cemented carbide bar stock, high-speed steel bar stock, or die steel bar stock.

[0039] S2. Simultaneously grind the PCD raw material and alloy bar to obtain the tool blank and tool body blank. The cylindricity and total runout of the tool body blank are both less than 0.0015 mm. Specifically, a centerless grinder is used to simultaneously grind the PCD raw material and alloy bar, resulting in high processing efficiency. This setup simultaneously controls the cylindricity and total runout of the tool body blank within 0.0015 mm, ensuring the reference accuracy of both the tool blank and the tool body blank, and providing a uniform and stable machining allowance for subsequent grooving and sharpening processes.

[0040] S3. Machining the rough blank of the tool body to form the tool holder 11 and the tool head 12. Specifically, the rough blank of the tool body is ground using a tool grinder. Further, the diameter of the tool head 12 is smaller than the diameter of the tool holder 11. This ensures that the small-diameter tool head 12 can reach into the workpiece machining area when the thread milling cutter is machining threads, effectively avoiding interference structures such as workpiece sidewalls and steps, and preventing the tool from rubbing and colliding with the workpiece; at the same time, the larger diameter of the rear tool holder 11 ensures overall rigidity, strong resistance to bending and impact during the cutting process, less prone to tool vibration, and higher dimensional accuracy of the machined threads.

[0041] S4. Machining the rough blank to form the body 21, cutting edge 22, and chip removal groove 23. Specifically, the cutting edge 22 and chip removal groove 23 are machined using laser equipment. This ensures that the cutting edge 22 is sharp, avoiding burrs during milling, while also preserving the wear resistance of the PCD material, thus improving the service life of the thread milling cutter.

[0042] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A thread milling cutter, characterized in that, include: Blade body (1); The blade (2) is fixedly connected to the blade body (1). The blade (2) includes a body (21) and a plurality of cutting edges (22) connected to the body (21). The plurality of cutting edges (22) are arranged circumferentially around the body (21). There is a chip removal groove (23) between two adjacent cutting edges (22). The orthographic projection of the plurality of chip removal grooves (23) along the axial direction of the blade body (1) is fan-shaped, and the orthographic projection of the plurality of chip removal grooves (23) along the axial direction of the blade body (1) has a central angle with a different angle.

2. The thread milling cutter according to claim 1, characterized in that, The cutting edge (22) includes a first cutting face (221), a second cutting face (222), and a third cutting face (223). The first cutting face (221) extends from the end face of the body (21) toward the blade body (1) and is angled to the end face of the body (21). The second cutting face (222) and the third cutting face (223) are arranged on opposite sides of the first cutting face (221) along a direction perpendicular to the axis of the blade body (1), and both the second cutting face (222) and the third cutting face (223) intersect the first cutting face (221) at an angle. The chip removal groove (23) is formed between the second cutting face (222) of one cutting edge (22) and the third cutting face (223) of the other cutting edge (22).

3. The thread milling cutter according to claim 2, characterized in that, The second cutting edge (222) includes a first inclined portion (2221) and a second inclined portion (2222) that intersect at an angle. The third cutting edge (223) includes a third inclined portion (2231) and a fourth inclined portion (2232) that intersect at an angle. The first inclined portion (2221) intersects the first cutting edge (221) at an angle. The second inclined portion (2222) intersects the fourth inclined portion (2232) of the adjacent cutting edge (22) at an angle. The third inclined portion (2231) intersects the first cutting edge (221) at an angle. The fourth inclined portion (2232) intersects the second inclined portion (2222) of the adjacent cutting edge (22) at an angle.

4. The thread milling cutter according to claim 3, characterized in that, The third inclined portion (2231) forms a radial front angle between its orthographic projection along the axial direction of the blade body (1) and the radial direction of the blade body (1), and the angle of the radial front angle is -10° to 10°.

5. The thread milling cutter according to claim 3, characterized in that, The fourth inclined portion (2232) forms an axial front angle between its radial projection on the blade body (1) and the axial direction of the blade body (1), and the angle of the axial front angle is 5°~10°.

6. The thread milling cutter according to claim 1, characterized in that, The central angle of the chip removal groove (23) projected along the axial direction of the cutter body (1) is 45°~135°.

7. The thread milling cutter according to claim 1, characterized in that, The blade body (1) includes a handle (11) and a blade head (12) arranged coaxially. One end of the blade head (12) is connected to the handle (11), and the other end of the blade head (12) is connected to the blade tip (2). The diameter of the blade head (12) is smaller than the diameter of the handle (11).

8. The thread milling cutter according to claim 1, characterized in that, The total runout tolerance of the plurality of said cutting edges (22) is less than 0.003 mm.

9. The thread milling cutter according to any one of claims 1-8, characterized in that, The blade body (1) is an alloy blade body; And / or, the cutting tool (2) is a PCD cutting tool.

10. A method for manufacturing a thread milling cutter, characterized in that, A method for manufacturing a thread end mill according to any one of claims 1-9, the method comprising the following steps: Welding PCD raw materials to alloy bars; Simultaneously grinding the PCD raw material and the alloy bar stock yields a tool blank and a tool body blank, wherein the cylindricity and total runout of the tool body blank are both less than 0.0015 mm; The rough blank of the tool body is machined to form a tool holder (11) and a tool head (12); The cutting blank is machined to form a body (21), a cutting edge (22), and a chip removal groove (23).

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