Tooth-forming cutting tools

Abstract

A tooth-forming tool includes a mounting base, a fastener, and a cutting tool body. The cutting tool body is assembled with the mounting base, and the fastener is also assembled with the mounting base and rests on the cutting tool body. The mounting base is also assembled with a rotating shaft, driven by the rotating shaft, and causes the cutting element in the circumferential direction of the cutting tool body to contact the workpiece to be machined and perform cutting, thereby obtaining a tooth-formed workpiece. Verification has shown that the tool of this invention, when used for tooth-forming machining, significantly improves machining accuracy and significantly reduces the fluctuation range of tool life.

Description

Technical Field

[0001] This utility model relates to a tool used in industrial production, and more particularly to a cutting tool for tooth forming on a workpiece. Background Technology

[0002] A gear is a mechanical part with teeth used for power transmission in mechanical systems. It transmits power, changes speed and torque, or changes the direction of motion through the meshing of the teeth.

[0003] The tool used for machining gears is called a honing wheel. It is a tool used for finishing gear tooth surfaces, and its shape resembles a gear with a tooth structure. In gear honing, the honing wheel and the gear being machined mesh with each other through their teeth. The relative sliding speed and pressure between the teeth are used to hone the gear tooth surface to improve the surface finish, precision, and roughness of the gear, as well as reduce gear noise.

[0004] Depending on their structure and application, honing wheels can be divided into gear-type honing wheels and worm-type honing wheels, etc. Their tooth structure is optimized and adjusted in design and parameters according to specific processing requirements. For example, the tooth shape and parameters of gear-type honing wheels are similar to those of ordinary gears, but they have special requirements in terms of tooth surface precision, roughness, and abrasive adhesion.

[0005] As processing continues, the precision shape on the gear-shaped honing wheel gradually wears down. At this point, a dressing tool is used to dress the honing wheel again to obtain a high-quality "mold" of the precision gear shape for continued processing. Consequently, various processing errors inherent in the dressing tool itself are "replicated" into the final gear product. Therefore, a high-quality honing wheel dressing tool is one of the key components in producing precision gears.

[0006] Currently, PCD materials have been applied to precision dressing tools for honing wheels. For example, products from Praewema Antriebstechnik GmbH obtain PCD sub-materials (shaped like discs, consisting of an upper PCD material layer and a lower carbide layer) from cylindrical PCD masterbatch. These sub-materials are then bonded to a base, and the cutting edges required for gear machining are formed on the outer edge of the PCD sub-materials.

[0007] The upper surface of common PCD materials is a mirror finish with a roughness of approximately 30 nanometers. This characteristic is highly beneficial for improving cutting performance and suppressing tool sticking. Therefore, it is an industry consensus that when forming cutting edges using PCD materials, a smooth upper surface should not be machined. Consequently, in cutting edge machining, the flank face is created by machining the PCD material laterally. However, due to the slight inclination and curvature of the PCD upper surface, the intersection line between the directly machined flank face and the upper surface will produce a contour deviation, which also brings inconvenience to cutting edge machining.

[0008] To address the aforementioned machining problems, Computer-Aided Manufacturing (CAM) software has been applied, significantly improving the machining efficiency of cutting tools using PCD material as the cutting edge. For example, with the assistance of such software, the machining coordinates of the PCD side are compensated by measuring the deviation between the actual and theoretical positions of preset measurement points on the upper surface of the PCD. This achieves automatic compensation of the machining path, thereby enabling the production of qualified PCD cutting edges solely based on the unmachined upper surface of the PCD material (i.e., the rake face) and by machining the corresponding sides of the PCD material (i.e., the flank face).

[0009] While this machining method can produce cutting tools for gear forming, such as honing wheels, the lifespan of each tool varies greatly, ranging from 300 to 30,000 gears. This is because the degree of coincidence of the intersection line (i.e., the cutting edge line) between the unprocessed PCD material upper surface and the processed PCD material side surface on the tool's cutting edge on the plane of rotation around the tool axis plays a decisive role in the tool's machining accuracy. However, the machining method of compensating for the machining coordinates of the PCD side surface by measuring the deviation between the actual and theoretical positions of preset measurement points on the PCD upper surface can only guarantee the coincidence of the projections of the cutting edge lines of each tooth on an end face perpendicular to the tool axis. At this point, the coincidence of the side surfaces (i.e., the tooth faces) of each tooth will inevitably decrease, causing additional indexing errors between the teeth and thus affecting the machining life of the gear forming tool. Utility Model Content

[0010] One objective of this invention is to provide a tooth-forming tool that reduces the lifespan fluctuation range of each tool and enhances the stability of the tool's lifespan.

[0011] Another objective of this invention is to provide a tooth-forming tool that reduces the warping of the rake face, which is beneficial for producing tooth-forming tools with high indexing accuracy and improving the machining accuracy of the tool.

[0012] In machining, the term "material" or "workpiece" typically refers to materials or semi-finished products used to manufacture parts or components; it is the object of machining during the mechanical process. That is, after machining the workpiece, a product that meets the machining or design requirements is obtained, such as hole-making tools and milling cutters. For workpieces used for tool machining, they typically include an axis, with the axial length greater than the radial length.

[0013] Precision machining refers to machining techniques that achieve extremely high levels of precision and surface quality. For example, in tool machining, dimensions, straightness, contour accuracy, surface roughness, and cutting edge radius are all achieved at a level exceeding micrometers.

[0014] Machining equipment (or machining centers) are processing devices with multiple axes of motion. These are the X, Y, and Z axes, which move along straight lines in a right-handed Cartesian coordinate system, and the A, B, and C axes, which rotate around the X, Y, and Z axes, respectively. For example, CNC machine tools typically have various control software programs that receive and issue commands in code form to automate the machining of workpieces. For instance, by forming the method for forming the drill tip of a machining tool provided in this invention into control code, it can be automated on the machining equipment to obtain products that meet the machining or design requirements.

[0015] In machining, indexing is an operation that precisely rotates a workpiece or cutting tool by a specific angle (or divides a circle into equal parts). Its core purpose is to machine products with equidistant, precisely angularly positioned characteristics. Indexing allows the same machining steps (such as milling, drilling, grinding, scribing, and inspection) to be repeated at different angular positions on the workpiece. Indexing (accuracy) error, also known as tooth pitch error, should be understood to include three aspects: adjacent tooth pitch error, cumulative tooth pitch error, and radial runout. In this invention, high indexing accuracy means high tooth pitch accuracy, including: adjacent tooth pitch error ≤ 7μm, cumulative tooth pitch error ≤ 15μm, and radial runout ≤ 15μm.

[0016] A tooth-forming tool includes a mounting base, a fastener, and a cutting tool body. The cutting tool body is assembled with the mounting base, and the fastener is also assembled with the mounting base and rests on the cutting tool body. The mounting base is also assembled with a rotating shaft, driven by the rotating shaft, and causes the cutting element in the circumferential direction of the cutting tool body to contact the workpiece to be machined and perform cutting, thereby obtaining a tooth-formed workpiece.

[0017] Another type of tooth-forming tool, including

[0018] The mounting base includes a mounting hole, a first mounting surface, and a second mounting surface, the first mounting surface and the second mounting surface intersect, and the first mounting hole is used for assembly with a rotating shaft.

[0019] The cutting tool body is assembled with the mounting base and includes a cutting part and a tool body. The cutting part is used to perform tooth forming cutting on the workpiece. The tool body is supported by a second mounting surface and has a second mounting hole that contacts the first mounting surface.

[0020] Fasteners, which are disposed on the cutter body and in contact with the cutter body, include a third mounting hole and are in contact with a first mounting surface.

[0021] The mounting base is driven to rotate by the rotating shaft. The first mounting surface is located on the outer edge of the circumferential direction of the rotating mounting hole and extends unidirectionally along the axial direction of the rotating shaft. In the opposite direction of the extension, it intersects with the second mounting surface.

[0022] The second assembly surface surrounds the outer periphery of the first assembly hole and extends outward from the hole.

[0023] The second mounting hole fits tightly with the first mounting surface.

[0024] The third assembly hole fits tightly with the first assembly surface.

[0025] The tooth forming tool of this utility model has a cutting body including a PCD layer. Its surface is processed to form a flat surface with a roughness Ra greater than or equal to 60 nanometers, especially greater than or equal to 0.1 micrometers. Using this as the rake face, the flank face is then processed accordingly. The life stability of the processed tool is significantly improved, and the fluctuation range of the tool life is reduced.

[0026] Below the PCD layer, an ultra-hard material layer is also provided, such as one made of hard alloy, which facilitates fixation to the mounting base, such as by bonding or welding.

[0027] The blade body is plate-shaped with round end faces at both ends, and the second mounting hole passes through both end faces.

[0028] The cutting section includes several toothed cutting parts, with the rake face being a PCD layer and the flank face intersecting the rake face, the intersection line forming the cutting edge.

[0029] Each cutting part has a three-dimensional tooth profile, including at least the tooth end face facing the fastener and the tooth lateral faces on both sides. In cutting, the tooth lateral faces are the contact surfaces of two teeth moving in opposite directions, also known as the meshing surfaces.

[0030] The included angle between the normals of the tooth end faces of any two toothed cutting parts is less than 0.1° to reduce indexing error. The included angle between the normal of the tooth end face of each toothed cutting part and the rotation axis of the tooth forming tool in the same plane is -2° to 2°, especially -1° to 1°, and preferably 0°.

[0031] During machining of a workpiece, the tooth-forming tool rotates (e.g., clockwise or counterclockwise), dividing the two sides of the toothed cutting part into a rotating side and a driven side, both forming a flank face. The cutting edge on the rotating side cuts the workpiece. The rotating side of the cutting part has a first helix angle (γ1), and the driven side has a second helix angle (γ2). γ1 ≤ the designed helix angle of the formed tooth, and γ2 ≥ the designed helix angle of the formed tooth.

[0032] A cutting edge line is formed by connecting the coordinate points of the spatial curve corresponding to the cutting edge of a cutting part. When the tool rotates around its axis, each cutting edge line rotates accordingly. Observed from the same position, the higher the degree of overlap of the trajectories of each cutting edge line at the observation position, the higher the machining accuracy of the tool. Increasing the degree of overlap improves the indexing accuracy. This invention discovers that the consistency of tooth pitch between teeth of various tooth-shaped cutting parts is closely related to the accuracy of tooth forming. Therefore, in manufacturing the tool of this invention, it is still necessary to pay attention to the morphological errors of the tooth-shaped cutting parts, especially the tooth profile shape of the meshing surface. During manufacturing, careful adjustment of tooth shape errors, tooth slope errors, and camber errors can significantly improve machining accuracy, enabling the tool to achieve a machining accuracy of within level 4 on the workpiece.

[0033] Another specific implementation of the tooth-forming tool is to process each tooth-shaped cutting part with a shape error of less than 3 micrometers, especially less than 1.5 micrometers.

[0034] Another specific implementation of the tooth-forming tool is to process each tooth profile cutting part with a tooth profile slope error of less than 8 micrometers, especially less than 5 micrometers.

[0035] Another specific implementation of the tooth-forming tool is to achieve a drum shape error of less than 4 micrometers, especially less than 2 micrometers, in machining each tooth-shaped cutting part.

[0036] The tooth forming tool provided by this utility model is used for tooth forming processing of workpieces. The tool's service life is significantly increased, with continuous processing of at least 20,000 pieces. The life fluctuation range is significantly reduced to ±10%. Taking gear processing as an example, due to the significant improvement in the consistency of each tooth, the indexing accuracy of the tool is reliably guaranteed. In actual use, the tool no longer suffers from abnormal damage such as premature tooth breakage after processing a few or dozens of pieces, making the tool's service life significantly more stable.

[0037] The tooth forming tool provided by this utility model is used for tooth forming of workpieces, resulting in significantly improved workpiece precision. Due to the significantly improved consistency of each tooth, the indexing accuracy of the tool is reliably guaranteed. During the honing wheel dressing process, the feed amount per tooth is more constant, reducing impact cutting, lowering vibration, and improving tooth waviness and high-order noise of the final product. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of an embodiment of the tooth-forming tool of this utility model;

[0039] Figure 2 for Figure 1 A cross-sectional view of the tooth-forming tool at one angle is shown.

[0040] Figure 3 This is a schematic diagram of an embodiment of the mounting base for the tooth forming tool of this utility model;

[0041] Figure 4 for Figure 3 A cross-sectional view of the mounting bracket at one angle;

[0042] Figure 5 This is a schematic diagram of one embodiment of the cutting tool body of this utility model. Detailed Implementation

[0043] The technical solution of this utility model is described in detail below with reference to the accompanying drawings. The embodiments of this utility model are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of the utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model.

[0044] Figure 1 This is a schematic diagram of an embodiment of the tooth-forming tool of this utility model. Figure 2 for Figure 1 The diagram shows a cross-sectional view of a tooth-forming tool at one angle. Figure 3 This is a schematic diagram of one embodiment of the mounting base for the tooth-forming tool of this utility model. Figure 4 for Figure 3 The diagram shows a cross-sectional view of the mounting bracket at one angle. (See attached image.) Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the gear-forming tool includes a mounting base 100, a fastener 300, and a cutting tool body 200. The cutting tool body 200 is assembled with the mounting base 100, and the fastener 300 is also assembled with the mounting base 100 and rests on the cutting tool body 200. The mounting base 100 is also assembled with a rotating shaft (not shown), which drives the cutting element 220 of the cutting tool body 200 in the circumferential direction to contact the workpiece to be processed and perform cutting, thereby obtaining a gear-forming workpiece, such as a gear with teeth. A tool specifically for processing gears is also called a honing wheel. It contacts the surface of the workpiece and, during simultaneous rotation, copies the tooth shape of the honing wheel onto the workpiece, thereby achieving gear forming on the workpiece.

[0045] PCD is currently one of the preferred materials for machining superhard materials in the field of industrial cutting tools. In this embodiment, the cutting tool body 200 includes a PCD layer 221 distributed on the end face of the cutting part 220. The end face typically extends outward along the rotational circumference, away from the rotation axis, and faces the fastener 300 resting on the cutting tool body 200. Below the PCD layer 221, a superhard material layer 222 made of cemented carbide is also provided to facilitate the fixing of the cutting tool body 200 to the mounting base 100, such as by bonding or welding.

[0046] In the machining of cutting tools, blanks for the mounting base 100, fastener 300, and cutting tool body 200 are first manufactured and assembled. Then, the blank for the cutting tool body 200 is ground to form the cutting edge. Through numerous tool manufacturing trials, it was found that first machining the PCD surface, such as wire cutting or laser turning, to form a smooth surface with a roughness Ra greater than or equal to 60 nanometers, especially greater than or equal to 0.1 micrometers, using this as the rake face, and then machining the flank face accordingly, improves the height difference of the various cutting parts 220 on the cutting tool body 200, making them closer to being arranged on the same plane, which significantly improves the tool's life stability. Taking gear machining as an example, verification showed that the tool life obtained through this machining process consistently remains above 20,000 internal gear machining operations (such as honing or dressing), significantly increasing the machining capacity and narrowing the life fluctuation compared to commercially available honing wheel tools.

[0047] The laser process employed is as follows: the workpiece is mounted on a rotating shaft through the center hole of the workpiece and rotated at a speed of 100 to 2000 rpm. At the same time, a pulsed laser with a pulse width of 500 femtoseconds to 500 nanoseconds, a repetition rate of 10 to 2500 kHz, and a power of 50 to 300 W is used to reciprocate and ablate the rotating workpiece in a direction roughly perpendicular to the workpiece's centerline to etch a reference PCD upper surface that is basically perpendicular to the center axis of the workpiece.

[0048] The process employs electrical discharge wire cutting, where the blank is mounted on a rotating shaft through the center hole and rotated at a speed of 100–2000 rpm. During the blank's rotation, electrical discharge grinding is continuously applied to improve the surface roughness of the PCD and to smooth out any minor protrusions that may be present in the material.

[0049] In the figure, the mounting base 100 includes a mounting hole 130, a first mounting surface 110, and a second mounting surface 120. The second mounting surface 120 surrounds the outer periphery of the mounting hole 130 and extends outwards from the periphery of the mounting hole 130, forming an "eave". The cutting tool body 200 rests on the second mounting surface 120. When the rotating shaft is mounted in the mounting hole 130, the rotating shaft rotates around the rotating shaft under the influence of an external force (e.g., a motor). Correspondingly, the mounting base 100 rotates synchronously with the rotating shaft. The first mounting surface 110 is located on the outer edge of the circumferential direction of the rotating hole 130, extends unidirectionally along the axial direction of the rotating shaft, and intersects with the second mounting surface 120 in the opposite direction of extension. Figure 3 (From a top-down perspective, the first assembly surface 110 stands on the second assembly surface 120).

[0050] Figure 5 This is a schematic diagram of one embodiment of the cutting tool body of this utility model, combined with... Figure 1 , Figure 2 , Figure 3 and Figure 4 ,like Figure 5 As shown, the cutting tool body 200 includes a cutting section 220 and a tool body 210. The tool body 210 is disc-shaped and is placed on and supported by the second mounting surface 120, and has a second mounting hole 230. The tool body 210 is plate-shaped with rounded end faces at both ends. The second mounting hole 230 passes through both end faces and is arranged along the axial direction of the tool body 210. The second mounting hole 230 contacts and assembles with the first mounting surface 110. The cutting section 220 is located at the radial outer edge of the tool body 210 away from the first mounting surface 110. During machining, it directly contacts the workpiece to perform tooth forming machining.

[0051] The fastener 300 includes a third mounting hole 310, which contacts and assembles with the first mounting surface 110 and presses against the cutter body 210, thereby enhancing the firmness of the cutting cutter body 200 fixed on the mounting base 100 and effectively preventing the cutting cutter body 200 from falling off the mounting base 100 due to force during rotation, which could lead to production accidents.

[0052] The cutting section 220 includes several cutting elements with three-dimensional tooth profiles. Each cutting element 223 is located at the radial outer edge of the tool body 210, away from the first mounting surface 110, and is arranged in a dispersed manner. Figure 1 and Figure 5 Each cutting element 223 includes at least a tooth end face 224 facing the fastener, and tooth side faces 225, 226 located on both sides. Each cutting element 223 performs tooth forming cutting on the workpiece during rotation.

[0053] The tooth end face is the face where the PCD (Precision Cutting Device) is located, and it includes the rake face. The tooth flank face includes the flank face, which intersects with the tooth end face to form the cutting edge, and a face extending from the flank face toward the second mounting surface 120. These faces define the local shape of the workpiece. The tooth flank face is typically at least two continuous curved surfaces that converge toward the tooth tip 227 of the workpiece, but do not necessarily intersect at the tooth tip; it is more common for them to intersect with the contour surface that defines the tooth tip.

[0054] During machining, when the tooth-forming tool rotates (e.g., clockwise or counterclockwise), the two sides of the tooth-shaped cutting part are divided into a rotating side and a driven side. Both sides form a flank face. The cutting edge on the rotating side cuts the workpiece. On the rotating side of the cutting part, there is a first helix angle (γ1), which is the difference between the designed helix angle of the formed tooth and the flank angle of the cutting edge. On the driven side, there is a second helix angle (γ2), which is the sum of the designed helix angle of the formed tooth and the flank angle of the cutting edge. γ1 ≤ the designed helix angle of the formed tooth, and γ2 ≥ the designed helix angle of the formed tooth. Angles γ1 and γ2 can also be the same.

[0055] The included angle between the normals of the tooth end faces of any two toothed cutting parts is less than 0.1°. The included angle between the normal of the tooth end face of each toothed cutting part and the rotation axis of the tooth forming tool lies in the same plane and is -2° to 2°, especially -1° to 1°, and more preferably 0°.

[0056] To achieve a machining accuracy of level 4 or lower for the workpiece, the tool in this embodiment has the following characteristics during manufacturing: shape error of each toothed cutting part is less than 3 micrometers, especially less than 1.5 micrometers; tooth profile slope error of each toothed cutting part is less than 8 micrometers, especially less than 5 micrometers; and crowning error of each toothed cutting part is less than 4 micrometers, especially less than 2 micrometers. The shape error (fHα), slope error (ffα), and crowning error (cα) can be detected according to ISO 1328-1:2013 standard.

Claims

1. A tooth-forming cutting tool, characterized in that: It includes a mounting base, fasteners, and a cutting tool body; the cutting tool body is assembled with the mounting base, and the fasteners are assembled with the mounting base and rest on the cutting tool body; the mounting base is also assembled with a rotating shaft, driven by the rotating shaft, and causes the cutting part in the circumferential direction of the cutting tool body to contact the workpiece to be processed and perform cutting, thereby obtaining a workpiece with toothed shape; The cutting tool body includes a PCD layer, the surface of which is machined to have a roughness Ra greater than or equal to 30 nanometers.

2. A tooth forming tool according to claim 1, characterised in that The surface of the PCD layer is processed to have a roughness Ra greater than or equal to 0.1 micrometers, which reduces the fluctuation range of tool life.

3. A tooth forming tool according to claim 1, characterised in that The cutting tool body includes a cutting section, which includes several toothed cutting parts. The rake face is a PCD layer, and the flank face intersects with the rake face. The intersection line forms the cutting edge.

4. The tooth-forming tool according to claim 3, characterized in that... The cutting part includes a plurality of toothed cutting elements, each having a three-dimensional tooth profile, including at least a tooth end face facing the fastener and tooth side faces on both sides.

5. The tooth-forming tool according to claim 3, characterized in that... The included angle between the normals of the tooth end faces of any two of the toothed cutting parts is less than 0.1°.

6. The tooth-forming tool according to claim 3, characterized in that... The angle between the normal to the tooth end face of each tooth-shaped cutting part and the rotation axis of the tooth forming tool lies in the same plane and is -2° to 2°.

7. The tooth-forming tool according to claim 3, characterized in that... The toothed cutting part has two sides divided into a rotating side and a driven side, and both sides form a back face. The cutting edge located on the rotating side cuts the workpiece. On the rotating side of the cutting part, there is a first helix angle γ1, where γ1 ≤ the design helix angle of the formed tooth.

8. The tooth-forming tool according to claim 7, characterized in that... The driven side has a second helix angle γ2, where γ2 ≥ the design helix angle of the formed tooth.

9. The tooth-forming tool according to claim 3, characterized in that... The shape error of each of the toothed cutting parts is less than 3 micrometers.

10. The tooth-forming tool according to claim 3, characterized in that... The tooth profile slope error of each of the aforementioned tooth-shaped cutting parts is less than 8 micrometers.

11. The tooth-forming tool according to claim 3, characterized in that... The drum shape error of each of the toothed cutting parts is less than 4 micrometers.

12. The tooth-forming tool according to claim 1, characterized in that... The mounting base includes a mounting hole, a first mounting surface, and a second mounting surface. The first mounting surface and the second mounting surface intersect, and the first mounting hole is used for assembly with a rotating shaft.

13. The tooth-forming tool according to claim 12, characterized in that... The cutting tool body and mounting base assembly includes a cutting part and a tool body. The cutting part is used to perform tooth forming cutting on the workpiece. The tool body is supported by a second mounting surface, on which a second mounting hole is provided, which contacts the first mounting surface.

14. The tooth-forming tool according to claim 13, characterized in that... The second mounting hole fits tightly with the first mounting surface.

15. The tooth-forming tool according to claim 12, characterized in that... The fastener is disposed on the cutter body and contacts the cutter body, including a third mounting hole and a first mounting surface.

16. The tooth-forming tool according to claim 15, characterized in that... The third mounting hole is tightly fitted with the first mounting surface.

17. The tooth-forming tool according to claim 12, characterized in that... The mounting base is driven to rotate by a rotating shaft. The first mounting surface is located on the outer edge of the rotating mounting hole in the circumferential direction and extends unidirectionally along the axial direction of the rotating shaft. In the opposite direction of the extension, it intersects with the second mounting surface.

18. The tooth-forming tool according to claim 12, characterized in that... The second assembly surface surrounds the outer periphery of the first assembly hole and extends outward from the hole.

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