A helical tooth cutting tool for hobbing

Abstract

The present application relates to the technical field of gear cutting tools, and particularly relates to a helical gear shaving tool for helical gear shaving, which comprises a tool body and gear teeth distributed along the circumference of the tool body, the gear teeth comprising a main relief surface, a plurality of cutting edges arranged in layers, and a front surface corresponding to each cutting edge, a sub-relief surface being arranged between each layer of cutting edges and the main relief surface, and the sub-relief surface being connected to the main relief surface; the rake angle of the top edge gradually decreases from the bottommost layer of cutting edges to the topmost layer of cutting edges, the relief angle of the top edge gradually increases from the bottommost layer of cutting edges to the topmost layer of cutting edges, and the angle between the main relief surface and the cutting plane is greater than the relief angle of the topmost layer of cutting edges; and each layer of cutting edges is conjugate to the tooth surface of the helical gear during the helical gear shaving process. The present application can reduce the wear of the gear teeth during the helical gear shaving process, and prolong the service life of the helical gear shaving tool.

Description

Technical Field

[0001] This invention relates to the field of tooth-removing tool technology, and more specifically to a helical tooth-removing tool for tooth-removing machining. Background Technology

[0002] Gear scraping tools are used for gear machining, achieving precise material removal through high-speed meshing with the workpiece. The principle of gear scraping is equivalent to the meshing transmission of a pair of interlocking gears. The tool and workpiece rotate at high speed, while either the workpiece or the tool moves along the workpiece's axis. At the cutting point, the combined rotational velocities of the tool and workpiece create a cutting velocity along the tooth direction, thus achieving scraping of the tooth surface. The resulting tiny, strip-shaped chips are discharged along the tooth profile. With its significant advantages of continuous cutting, high efficiency and precision, and environmental friendliness, gear scraping has become a core machining solution for gear parts in high-end equipment such as automotive automatic transmissions and robot precision reducers.

[0003] In existing rebar cutting tools, the entire cutting edge of the tool participates in the cutting process simultaneously. The cutting contact between the tool's cutting edge and the workpiece is a line contact. In spur gear machining, the contact line is a straight line along the tooth width direction. However, in helical gear machining, the line contact characteristic of the cutting edge and the workpiece is amplified by the helix angle of the helical gear. Furthermore, due to the spatial differences in the micro-segments on the cutting edge, the radial penetration depth of the micro-segments on the tooth tip side is significantly greater than that on the tooth root side. As the contact time is prolonged, the force and thermal loads are continuously highly concentrated in the tooth tip and cut-out side areas. This localized load concentration easily leads to tool edge wear, and the high-temperature environment accelerates the oxidation and diffusion wear of the tool material, affecting the tool life.

[0004] Therefore, an improved cutting tool scheme suitable for helical tooth cutting is proposed to reduce tool edge wear and extend the cutting tool life. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a helical tooth cutting tool for helical tooth cutting, which reduces tool edge wear during the helical tooth cutting process and extends the tool's lifespan.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a helical tooth cutting tool for tooth cutting, comprising a tool body and cutting teeth distributed along the circumference of the tool body, the cutting teeth comprising a main flank face, a plurality of cutting edges arranged in layers and a rake face corresponding to each of the cutting edges, and a secondary flank face provided between each layer of cutting edges and the main flank face, the secondary flank face being connected to the main flank face; The rake angle of the cutting edge gradually decreases from the bottom cutting edge to the top cutting edge, and the clearance angle of the cutting edge gradually increases from the bottom cutting edge to the top cutting edge. The angle between the main clearance face and the cutting plane is greater than the clearance angle of the top cutting edge. Each layer of cutting edge is conjugate with the tooth surface of the helical tooth being machined during the tooth cutting process.

[0007] Furthermore, the height of the cutting edge decreases gradually in the direction perpendicular to the cutting speed, and the height difference between the cutting edges of adjacent layers is 0.05~0.25mm.

[0008] Furthermore, the inclination angle of each cutting edge is 2–3°.

[0009] Furthermore, the formula for calculating the inclination angle of each cutting edge is as follows:

[0010] in, Let be the inclination angle of the i-th layer of cutting edge; The reference blade inclination angle is set at 2.5°. This is the sequence correction factor for the dip angle; For fine-tuning, use ±0.5°; This refers to the axial feed rate; The angle between the workpiece axis and the tool axis; Let be the cutting speed of the i-th layer of cutting edges.

[0011] Furthermore, the rake angle of each cutting edge is 3–12°.

[0012] Furthermore, the formula for calculating the rake angle of each cutting edge is as follows:

[0013] in, Let be the rake angle of the top edge of the i-th layer of cutting edge; As the reference front angle, take 8°; This is the sequence correction factor for the front angle of the tip edge; Let i be the cutting depth of the i-th layer; This represents the total cutting depth of a single cutting tooth.

[0014] Furthermore, the depth of cut gradually decreases from the bottommost cutting edge to the topmost cutting edge; the depth of cut for each layer is 0.1–0.8 mm. .

[0015] Furthermore, the clearance angle of each cutting edge is 6–12°.

[0016] Furthermore, the formula for calculating the clearance angle of each cutting edge is as follows:

[0017] in, Let be the tip clearance angle of the i-th layer of cutting edge; As the reference back angle, take 9°; This is the sequence correction factor for the back angle of the top edge; The basic adjustment should be 1 to 2 degrees. The height difference between the cutting edge of the i-th layer and the adjacent layer; Let be the contact length between the i-th layer of cutting edge and the workpiece.

[0018] Furthermore, the cutting edge has 3 to 5 layers.

[0019] The above approach has the following beneficial effects: 1. Existing helical tooth cutting tools, due to simultaneous cutting with the entire cutting edge, experience highly concentrated force and heat loads on the tooth tip and cutting side, leading to severe localized wear and short service life. This technical solution addresses this by layering the cutting edges and distributing cutting depths according to roughing, intermediate cutting, and finishing. Combined with a differentiated design where the rake angle of the top edge gradually decreases from the bottom to the top, while the clearance angle gradually increases, the load on each layer of the cutting edge is evenly distributed, effectively avoiding localized load concentration. Simultaneously, the split clearance face design connecting each layer of the cutting edge to the main clearance face further optimizes the tool's stress state. Combined with the inclination angle guiding smooth chip removal, it reduces the additional heat generated by friction between the tool and chips. Compared to existing technologies, this improves the uniformity of cutting edge wear and extends the service life of the cutting tool.

[0020] 2. In existing technologies, helical gear machining is prone to problems such as tooth direction error and tooth surface scratches due to the amplified helix angle caused by the line contact characteristics between the cutting edge and the workpiece. This technical solution, however, effectively compensates for the helix error in helical gear machining by ensuring that each layer of cutting edges is conjugate to the tooth surface of the helical gear being machined, and by precisely matching the tool helix angle with the workpiece helix angle. Combined with the gradual trimming effect of small allowances from layered cutting, this approach effectively compensates for the helix error in helical gear machining. Specifically, the smaller cutting depth of the finishing layer and the appropriate top edge angle design enable precise trimming of the tooth surface micro-morphology. Simultaneously, the layered, sequential contact cutting method significantly reduces the abrupt change in cutting force, suppressing vibrations in the machining system. The design where the angle between the main flank face and the cutting plane is greater than the top edge clearance angle of the top cutting edge avoids interference friction between the tool and the machined tooth surface, ultimately resulting in a significant reduction in tooth surface roughness.

[0021] 3. Existing technologies require conservative selection of cutting parameters for machining helical teeth and thin-walled parts, resulting in limited efficiency. This technical solution, however, utilizes layered load design to distribute the total cutting depth of a single tooth across multiple cutting edges for gradual removal. This reduces the peak cutting force of a single edge compared to traditional tools, effectively controlling the machining deformation of thin-walled helical teeth. Furthermore, by designing the cutting depth ratio and axial feed rate of each layer, machining efficiency can be improved compared to existing single-edge tools while maintaining machining quality. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the helical tooth cutting tool for tooth cutting according to the present invention; Figure 2 This is a schematic diagram of the tooth structure of an embodiment of the helical tooth cutting tool for tooth cutting according to the present invention; Figure 3 This is a schematic diagram of the cutting edge structure of an embodiment of the helical tooth cutting tool for tooth cutting according to the present invention; Figure 4 This is a schematic diagram of the machining state of an embodiment of the helical tooth cutting tool of the present invention for tooth cutting.

[0023] The reference numerals in the accompanying drawings include: 10, tool body; 11, cutting tooth; 12, rake face; 13, cutting edge; 14, flank face; 15, main flank face. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0025] The following detailed description illustrates the specific implementation method: A helical gear cutting tool is used for gear cutting. In this embodiment, the cutting tool is mainly suitable for cutting helical gears. In some other embodiments, the cutting tool is also suitable for cutting spur gears. Figure 1 As shown, Figure 1 The left side is an isometric view of the tooth-removing tool in this embodiment. Figure 1 The right side is a partially enlarged schematic diagram of a single cutting tooth 11 in an isometric view; the cutting tool of this embodiment is similar to existing cutting tools in that it mainly consists of a tool body 10 and cutting teeth 11 distributed along the circumference of the tool body 10. The tool body 10 is mainly used to connect the cutting tool to the tool shaft, and the cutting teeth 11 are mainly used to perform cutting operations on the workpiece. Figure 1 A partially enlarged schematic diagram of a single cutting tooth 11 and Figure 2 As shown, Figure 2 This is an isometric view of a single cutting tooth 11 in this embodiment. The cutting tool of this embodiment differs from existing cutting tools in that the cutting tooth 11 includes a main flank face 15 and a plurality of layered cutting edges 13. Preferably, the number of layers of cutting edges 13 is 3 to 5. Furthermore, a secondary flank face 14 is provided between the main flank face 15 and each layer of cutting edges 13, with both ends of the secondary flank face 14 connecting to the main flank face 15 and the corresponding layer of cutting edges 13, respectively. In addition, each layer of cutting edges 13 has a corresponding independent rake face 12.

[0026] like Figure 3 As shown, Figure 3 The bottom view is a top view of the tooth-removing tool. Figure 3 The top section shows, in sequence, the top view of the cutting tool, sectional views AA, BB, and CC. Each of the AA, BB, and CC sections includes a magnified view of the cutting edge 13 on its right side. In this embodiment, the rake angle of each layer is different. Specifically, the rake angle of the cutting edge 13 gradually decreases from the bottommost cutting edge 13 to the topmost cutting edge 13. Preferably, the rake angle of each cutting edge 13 is between 3 and 12°. The rake angle of each layer can be designed based on the following formula:

[0027] in, Let be the rake angle of the top edge of the i-th cutting edge 13; As the reference front angle, take 8°; This is the sequence correction factor for the front angle of the tip edge; Let i be the cutting depth of the i-th layer; This represents the total cutting depth of a single cutting tooth (11).

[0028] This embodiment uses a three-layer cutting edge 13 as an example, defining the three cutting edges 13 as the roughing layer, intermediate layer, and finishing layer, respectively used for roughing, intermediate cutting, and finishing. The aforementioned top edge rake angle layer sequence correction coefficient... The corresponding values ​​are set as follows: when the coarse cutting layer i=1, When the intermediate layer i=2, When the precision cutting layer i=3, .

[0029] In this embodiment, the cutting depth of the cutting edge 13 in each layer is 0.1~0.8 mm. Preferably, the total cutting depth of a single cutting tooth 11 is maintained within the range of 0.1–0.3 mm, balancing the machining accuracy and efficiency; the cutting depth of the cutting edge 13 for the roughing layer is 0.1–0.7 mm. The cutting depth of the cutting edge 13 for the intermediate cutting layer is 0.2–0.3 mm. The cutting depth of the cutting edge 13 for the precision cutting layer is 0.1. This distributes the total cutting depth of the single cutting tooth 11 across three layers of cutting edges 13, while ensuring cutting efficiency.

[0030] like Figure 3 As shown, the clearance angle of each layer in this embodiment is also different. Specifically, the clearance angle of the cutting edge 13 from the bottommost cutting edge 13 to the topmost cutting edge 13 gradually increases; preferably, the clearance angle of each cutting edge 13 is between 6 and 12°; the clearance angle of each layer can be designed based on the following formula:

[0031] in, Let be the tip clearance angle of the i-th layer of cutting edge; As the reference back angle, take 9°; This is the sequence correction factor for the back angle of the top edge; The basic adjustment should be 1 to 2 degrees. The height difference between the cutting edge 13 of the i-th layer and the adjacent layer; The contact length between the i-th cutting edge 13 and the workpiece.

[0032] The above-mentioned sequence correction factor for the back angle of the top edge The corresponding values ​​are set as follows: when the coarse cutting layer i=1, When the intermediate layer i=2, When the precision cutting layer i=3, In this embodiment, the height of the cutting edge 13 decreases gradually in the direction perpendicular to the cutting speed, and the height difference between adjacent cutting edges 13 is preferably set to 0.05~0.25mm; thus: , , The contact length between the cutting edge 13 and the workpiece can be obtained through simulation of the cutting edge sweep. , , .

[0033] Based on the above design, the clearance angle of the main relief face 15 must be greater than that of the topmost cutting edge 13 to avoid interference between the main relief face 15 and the workpiece. like Figure 3 As shown, in this embodiment, the rake angle of each cutting edge 13 is between 2 and 3°; the rake angle of each layer can be designed based on the following formula:

[0034] in, Let be the inclination angle of the i-th cutting edge 13; The reference blade inclination angle is set at 2.5°. The step sequence correction factor is the dip angle. In this embodiment... All values ​​are 0 to ensure consistent chip flow direction; For fine-tuning, use ±0.5°; The axial feed rate is 0.1–0.2 mm / r during gear cutting. The angle between the workpiece axis and the tool axis; Let be the cutting speed of the i-th cutting edge 13, calculated using the following formula:

[0035] in, Let be the trajectory diameter of the i-th layer cutting edge 13; This refers to the operating speed of the gear cutting tool.

[0036] The cutting tool based on the above design is suitable for helical tooth cutting. Each layer of cutting edge 13 is conjugate with the tooth surface of the helical tooth being cut during the cutting process.

[0037] Taking the internal helical gear sleeve as an example, the specific implementation process is as follows: Basic parameters of the workpiece: the module of the internal helical gear sleeve is 2.5mm, the number of teeth of the internal helical gear sleeve is 36, the helix angle of the internal helical gear sleeve is 15°, the tooth width is 20mm, the inner diameter of the sleeve is 90mm, and the total cutting allowance of a single tooth groove (total cutting depth of a single tooth 11) is 0.3mm.

[0038] Calculate the number of teeth of the cutting tool ; These are the speed ratios during machining of the gear cutting tool and the gear sleeve, respectively; typically , This refers to the number of teeth on the internal helical gear sleeve. That is, the cutter has 24 teeth. The helix angle of the cutter and the helix angle of the gear sleeve are equal, both at 15°. The cutter body diameter... , The initial radial clearance is set at 5 mm. The inner diameter of the gear sleeve can be used to calculate the diameter of the tool body. Center distance (distance between the tool and workpiece axes, ensuring conjugate contact). From this, the center distance can be calculated. Tool speed Typically rounded to 550 r / min. Axial feed rate. ( Load factor, Material hardness, 1451 N / mm²; axial feed rate is calculated from this. A reasonable value is usually selected. .

[0039] Calculation of cutting depth for each layer: Three cutting edges (13): the roughing layer is used for rapid removal of allowance and to avoid thin-wall deformation; the intermediate layer is used to correct roughing errors and smooth the tooth surface; the finishing layer is used to ensure tooth surface accuracy and helix quality. Planning the cutting depth of each cutting edge (13). The rough cut layer is rounded to 0.18mm (0.6). The mid-section is rounded to 0.08mm (0.27). The precision-cut layer is rounded to 0.04mm (0.13). ).

[0040] Geometric angle calculation: (1) Top edge rake angle:

[0041]

[0042]

[0043] That is, the rake angle of the cutting edge 13 of the rough cutting layer is 9°, the rake angle of the cutting edge 13 of the intermediate cutting layer is 8°, and the rake angle of the cutting edge 13 of the finish cutting layer is 7°.

[0044] (2) Back angle of the top edge: Preset ; calculate ; (Rounded down to 9°); (Rounded to 11°).

[0045] That is, the top edge relief angle of the cutting edge 13 in the roughing layer is 9°, the top edge relief angle of the cutting edge 13 in the intermediate layer is 9°, and the top edge relief angle of the cutting edge 13 in the finishing layer is 11°.

[0046] (3) Cutting edge inclination angle: Preset reference cutting edge angle 2.5°, axial feed rate Cutting speed .

[0047] Rounded to 2.4°.

[0048] That is, the rake angle of each cutting edge 13

[0049] Calculation of cutting edge 13 length (covering 40%~80% of tooth width): Coarse cut layer:

[0050] Mid-section:

[0051] Precision cut layer:

[0052] That is, the cutting edge 13 of the roughing layer is 16mm long, the cutting edge 13 of the intermediate layer is 12mm long, and the cutting edge 13 of the finishing layer is 8mm long.

[0053] Lead calculation for helical helical gears:

[0054] in, For modulus, The helix angle of the cutting tool.

[0055] The final machining state of the gear cutting tool is obtained as follows: Figure 4 As shown in Table 1, the various design parameters are as follows: Table 1 Design parameters of the tooth-removing tool Depth of cut 0.18mm 0.08mm 0.04mm Front corner 9° 8° 7° rear corner 9° 9° 11° blade inclination angle 2.4° (dextral) 2.4° (dextral) 2.4° (dextral) Inter-story height difference - 0.12mm 0.22mm Cutting edge length 16mm 12mm 8mm helical lead 30.33mm 30.33mm 30.33mm Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A helical tooth cutting tool for tooth cutting, comprising a tool body and cutting teeth distributed along the circumference of the tool body, characterized in that, The cutting tooth includes a main flank face, a plurality of cutting edges arranged in layers, and a rake face that corresponds one-to-one with each of the cutting edges. Each layer of cutting edges is provided with a secondary flank face between it and the main flank face, and the secondary flank face is connected to the main flank face. The height of the cutting edge decreases gradually in the direction perpendicular to the cutting speed, and the height difference between the cutting edges of adjacent layers is 0.05~0.25mm; The formulas for calculating the rake angle of each cutting edge are as follows: ； in, Let be the rake angle of the top edge of the i-th layer of cutting edge; As the reference front angle, take 8°; This is the sequence correction factor for the front angle of the tip edge; Let i be the cutting depth of the i-th layer; This represents the total cutting depth of a single cutting tooth. The depth of cut gradually decreases from the bottom cutting edge to the top cutting edge; the depth of cut for each layer is 0.1~0.

8. ; The cutting edge has 3 to 5 layers; The rake angle of the cutting edge gradually decreases from the bottom cutting edge to the top cutting edge, and the clearance angle of the cutting edge gradually increases from the bottom cutting edge to the top cutting edge. The angle between the main clearance face and the cutting plane is greater than the clearance angle of the top cutting edge. Each layer of cutting edge is conjugate with the tooth surface of the helical tooth being machined during the tooth cutting process.

2. The helical tooth cutting tool for tooth cutting according to claim 1, characterized in that, The inclination angle of each cutting edge is 2~3°.

3. The helical tooth cutting tool for tooth cutting according to claim 1, characterized in that, The formula for calculating the inclination angle of each cutting edge is as follows: ； in, Let be the inclination angle of the i-th layer of cutting edge; The reference blade inclination angle is set at 2.5°. This is the sequence correction factor for the dip angle; For fine-tuning, use ±0.5°; This refers to the axial feed rate; The angle between the workpiece axis and the tool axis; Let be the cutting speed of the i-th layer of cutting edges.

4. The helical tooth cutting tool for tooth cutting according to claim 1, characterized in that, The rake angle of each cutting edge is 3~12°.

5. The helical tooth cutting tool for tooth cutting according to claim 1, characterized in that, The clearance angle of each cutting edge is 6~12°.

6. The helical tooth cutting tool for tooth cutting according to claim 1, characterized in that, The formulas for calculating the clearance angle of each cutting edge are as follows: ； in, Let be the tip clearance angle of the i-th layer of cutting edge; As the reference back angle, take 9°; This is the sequence correction factor for the back angle of the top edge; The basic adjustment should be 1~2°. The height difference between the cutting edge of the i-th layer and the adjacent layer; Let be the contact length between the i-th layer of cutting edge and the workpiece.

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