Rotary tool and method for manufacturing a machined product

Abstract

The purpose of the present invention is to achieve both an improvement in the surface roughness of a machined surface, and an improvement in the durability of a main edge and an auxiliary edge, which are cutting edges. An auxiliary flank surface has: a flat second flank surface which is adjacent to the auxiliary edge at the rear thereof in the direction of rotation of a rotary shaft; and a flat third flank surface which is adjacent to the second flank surface at the rear thereof in the direction of rotation of the rotary shaft. In a tip-end view of the main body from the tip end, the maximum value of the width of the second flank surface in the direction perpendicular to the auxiliary edge is smaller than the maximum value of the width of the main flank surface in the direction perpendicular to the main edge, and the clearance angle of the second flank surface is smaller than the clearance angle of the main flank surface.

Description

Technical Field

[0001] The present disclosure relates to a rotary tool used for cutting a workpiece to be cut, for example, turning, and a method for manufacturing a cut workpiece.

Background Art

[0002] As a rotary tool used for turning a workpiece made of a metal material or the like, for example, an end mill described in Patent Document 1 is known. The end mill described in Patent Document 1 has, for example, a ball edge as a cutting edge and a round surface as one of the relief surfaces located along the cutting edge. The round surface is a surface having a relatively small relief angle among a plurality of relief surfaces. By bringing this round surface into contact with the workpiece during cutting of the workpiece, the vanishing effect by the round surface, in other words, the relief surface, can be exerted to improve the surface roughness of the machined surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A rotary tool according to one aspect of the present disclosure extends along a rotation axis from a first end to a second end and includes a cylindrical main body. The main body has a chisel edge located on the first end side and intersecting the rotation axis, a parent cutting edge located on the first end side and extending from the chisel edge toward the outer peripheral side, a flat parent relief surface adjacent to the parent cutting edge behind in the rotation direction of the rotation axis, a child cutting edge located on the first end side and extending from a position separated from the chisel edge toward the outer peripheral side, and a child relief surface adjacent to the child cutting edge behind in the rotation direction of the rotation axis. The child relief surface has a flat secondary relief surface adjacent to the child cutting edge behind in the rotation direction of the rotation axis and a flat tertiary relief surface adjacent to the secondary relief surface behind in the rotation direction of the rotation axis. When the main body is viewed from the tip toward the first end, a maximum value of the width of the secondary relief surface in a direction orthogonal to the child cutting edge is smaller than a maximum value of the width of the parent relief surface in a direction orthogonal to the parent cutting edge. A relief angle of the secondary relief surface is smaller than a relief angle of the parent relief surface.

Brief Description of the Drawings

[0005]

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Embodiments for Carrying Out the Invention

[0006] Hereinafter, as an example of a rotary tool according to an embodiment of the present disclosure, an end mill and a method for manufacturing a machined product will be described in detail with reference to the drawings. However, each drawing referred to below shows only the components necessary for explaining the embodiment, simplified for convenience of explanation. Therefore, the end mill as an example of the rotary tool may include any components not shown in each of the drawings referred to. Also, the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components and the dimensional ratios of the components.

[0007] In the present disclosure, the rotation axis refers to the rotation axis (axis of rotation) of the rotary tool, the circumferential direction refers to the direction around the rotation axis, in other words, the circumferential direction of the outer peripheral surface of the main body. The outer peripheral side refers to the direction or side facing the outer peripheral surface of the main body. The radial direction refers to the direction orthogonal to the rotation axis and the circumferential direction. The radially outer side refers to the direction or side away from the rotation axis in the radial direction. "RD" in FIGS. 6 and 7 indicates the circumferential direction.

[0008] With reference to FIGS. 1 to 7, the configuration of an end mill 10, which is an example of the rotary tool according to the embodiment, will be described. FIG. 1 is a perspective view of the end mill according to the embodiment. FIG. 2 is an enlarged perspective view of part II in FIG. 1. FIG. 3 is a front view of the end mill shown in FIG. 1. FIG. 4 is a side view of the end mill as viewed from the IV direction in FIG. 3. FIG. 5 is a side view of the end mill as viewed from the V direction in FIG. 3. FIG. 6 is an enlarged view of a cross section taken along line VI-VI in FIG. 3. FIG. 7 is an enlarged view of a cross section taken along line VII-VII in FIG. 3.

[0009] As shown in Fig. 1, an end mill 10, which is an example of a rotary tool according to this embodiment, is an end mill used for cutting (turning) a workpiece W (see Fig. 8) made of a metal material or the like. Examples of the cutting of the workpiece W include shoulder cutting, groove cutting, R cutting, and profiling. The end mill 10 is, for example, a solid-type end mill made of a hard material. Examples of the hard material include high-speed tool steel, cemented carbide, ceramics, cermet, cBN (Cubic Boron Nitride), and PCD (PolyCrystalline Diamond). The end mill 10 may be composed of only one of the above materials, or may be composed of a plurality of materials. For example, the end mill 10 may have a structure in which cemented carbide is used as a base and is coated with PCD.

[0010] The end mill 10 includes a cylindrical main body 12, and the main body 12 extends along the rotation axis S from the tip (first end) 12a to the rear end (second end) 12b. The main body 12 has a cutting portion 14 that contacts the workpiece W (see Fig. 11) on the tip 12a side to perform cutting. The main body 12 has a shank portion 16 on the rear end 12b side that is attached to the spindle of a machine tool via an arbor. If at least the cutting portion 14 is made of, for example, the above-described hard material, the end mill 10 does not have to be a solid-type end mill.

[0011] As shown in FIGS. 1 and 2, the cutting portion 14 has a plurality of discharge grooves 18 for discharging chips generated by cutting. The plurality of discharge grooves 18 are spaced along the circumferential direction of the outer peripheral surface of the main body 12, and each discharge groove 18 extends spirally from the tip 12a side of the main body 12 toward the rear end 12b side. The cutting portion 14 has an outer peripheral blade 20 located at the outer peripheral end of the wall surface on the side facing the rotation direction T of the rotation axis S in each discharge groove 18. Each outer peripheral blade 20 extends spirally from the tip 12a side of the main body 12 toward the rear end 12b side. The cutting portion 14 has a rake face 22 located on the discharge groove 18 side of each outer peripheral blade 20, and a flank face 24 adjacent to the rake face 22 on the rear side (opposite to the rotation direction T) of the rotation direction T of the rotation axis S. Each outer peripheral blade 20 is located at the intersection of each rake face 22 and each flank face 24.

[0012] As shown in FIGS. 2 and 3, the cutting portion 14 has a chisel edge 26 that intersects the rotation axis S, and the chisel edge 26 is located on the tip 12a side of the main body 12. The chisel edge 26 may have a biting action on the workpiece W.

[0013] As shown in FIGS. 2 to 4, the cutting portion 14 has two main blades 28 located on the tip 12a side of the main body 12, in other words, as bottom blades. Each main blade 28 extends from the chisel edge 26 toward the outer peripheral side of the main body 12. The two main blades 28 may be rotationally symmetric about the rotation axis S. Each main blade 28 may be inclined with respect to the radial direction of the main body 12, in other words, the direction orthogonal to the rotation direction T and the circumferential direction of the rotation axis S, so as to approach the rear end 12b side of the main body 12 as it approaches the rotation axis S. The cutting portion 14 has a planar main rake face 30 located on the discharge groove 18 side of each main blade 28, and a flat main flank face 32 adjacent to each main blade 28 on the rear side of the rotation direction T. Each main blade 28 is located at the intersection of each main rake face 30 and each main flank face 32. The two main flank faces 32 may be connected by the chisel edge 26. In other words, the chisel edge 26 may be located at the intersection of the two main flank faces 32.

[0014] The cutting part 14 may have a corner part 34 located at the radially outer end of each parent cutting edge 28. Each corner part 34 is smoothly connected to the tip of the outer peripheral cutting edge 20 and may function as a cutting edge.

[0015] As shown in FIGS. 2, 3, and 5, the cutting part 14 has two sub-cutting edges 36 as bottom cutting edges located on the tip 12a side of the main body 12. Each sub-cutting edge 36 extends from a position away from the chisel edge 26 toward the outer peripheral side of the main body 12. The two sub-cutting edges 36 may be rotationally symmetrically located about the rotation axis S. Each sub-cutting edge 36 may be parallel to the radial direction of the main body 12. The cutting part 14 has a planar sub-rake face 38 located on the side of the discharge groove 18 of each sub-cutting edge 36, and a sub-relief face 40 adjacent to each sub-cutting edge 36 behind in the rotation direction T of the rotation axis S. Each sub-cutting edge 36 is located at the intersection of each sub-rake face 38 and each sub-relief face 40. The number of sub-cutting edges 36 is not limited to two, and may be one or three or more.

[0016] The cutting part 14 may have a corner part 42 located at the radially outer end of each sub-cutting edge 36. Each corner part 42 is smoothly connected to the tip of the outer peripheral cutting edge 20 and may function as a cutting edge.

[0017] As shown in FIGS. 2 and 3, each child relief surface 40 has two flat secondary relief surfaces 44 adjacent to each other behind the child cutting edge 36 in the rotation direction T of the rotation axis S, and flat tertiary relief surfaces 46 adjacent to each other behind the secondary relief surfaces 44 in the rotation direction T of the rotation axis S. When the main body 12 is viewed from the tip 12a in the tip view, the maximum value C1 of the width of each secondary relief surface 44 in the direction orthogonal to each child cutting edge 36 is smaller than the maximum value C2 of the width of each tertiary relief surface 46 in the direction orthogonal to each child cutting edge 36. When the main body 12 is viewed from the tip 12a in the tip view, the maximum value C1 of the width of each secondary relief surface 44 in the direction orthogonal to each child cutting edge 36 is smaller than the maximum value C3 of the width of each parent relief surface 32 in the direction orthogonal to each parent cutting edge 28. When the main body 12 is viewed from the tip 12a in the tip view, each secondary relief surface 44 may have a first region 44a in which the width C1 in the direction orthogonal to each child cutting edge 36 is constant. The first region 44a of each secondary relief surface 44 may be wider than other regions of each secondary relief surface 44.

[0018] As shown in FIGS. 6 and 7, the relief angle θ1 of each secondary relief surface 44 is smaller than the relief angle θ2 of each tertiary relief surface 46. The relief angle θ1 of each secondary relief surface 44 is smaller than the relief angle θ3 of each parent relief surface 32. The relief angle θ2 of each tertiary relief surface 46 may be larger than the relief angle θ3 of each parent relief surface 32.

[0019] As shown in FIGS. 2 and 3, the cutting portion 14 has a gash surface 48 located on the side of the rake face 30 of each parent cutting edge 28. Each gash surface 48 is inclined radially so as to approach the rear end 12b of the main body 12 as it approaches the outer peripheral side of the main body 12. Thereby, while securing a space for flowing the chips generated by the two parent cutting edges 28, it is possible to avoid the core thickness of the end mill 10 from becoming excessively thin.

[0020] According to the configuration of the end mill 10 according to the present embodiment, as described above, the relief angle θ1 of each secondary relief surface 44 is smaller than the relief angle θ3 of each primary relief surface 32. Therefore, the vanishing effect by each secondary relief surface 44 can be exerted, and the surface roughness of the machined surface can be improved. Although a large cutting load is likely to be applied to each primary cutting edge 28 compared to the sub-cutting edges 36, it is difficult to exert the vanishing effect by each primary relief surface 32, and it is possible to avoid an excessive cutting load being applied to each primary cutting edge 28 and improve the durability of each primary cutting edge 28.

[0021] Also, as described above, when the main body 12 is viewed from the tip 12a in the tip view, the maximum value C1 of the width of each secondary relief surface 44 in the direction orthogonal to each sub-cutting edge 36 is smaller than the maximum value C3 of the width of each primary relief surface 32 in the direction orthogonal to each primary cutting edge 28. Therefore, it becomes difficult for an excessive vanishing effect to be exerted by each secondary relief surface 44, and it is possible to avoid an excessive cutting load being applied to each sub-cutting edge 36 and improve the durability of each sub-cutting edge 36.

[0022] That is, according to the end mill 10 of the present embodiment, it is possible to achieve both an improvement in the surface roughness of the machined surface and the durability of each primary cutting edge 28 and each sub-cutting edge 36.

[0023] When the relief angle θ2 of each tertiary relief surface 46 is larger than the relief angle θ3 of each primary relief surface 32, it becomes difficult for the vanishing effect by each tertiary relief surface 46 to be exerted. Thereby, each tertiary relief surface 46 can avoid an excessive cutting load being applied to each sub-cutting edge 36 and further improve the durability of each sub-cutting edge 36.

[0024] When each sub-edge 36 is parallel to the radial direction of the main body 12, the cutting load applied to each sub-edge 36 can be reduced, and the durability of each sub-edge 36 can be further improved. Here, when each sub-edge 36 is parallel to the radial direction of the main body 12, as shown in FIG. 5, it means that each sub-edge 36 is orthogonal to the rotation axis S. Further, when each main-edge 28 is inclined with respect to the radial direction of the main body 12 so as to approach the rear-end 12b side of the main body 12 as it approaches the rotation axis S, each main-edge 28 can easily come into contact with the workpiece stably. Here, when each main-edge 28 is inclined with respect to the radial direction of the main body 12 so as to approach the rear-end 12b side of the main body 12 as it approaches the rotation axis S, in an example shown in FIG. 4, it means that the main-edge 28 is inclined so as to go to the left as it approaches the rotation axis S. Thereby, each main-edge 28 can reduce the cutting load applied to each main-edge 28 and further improve the durability of each main-edge 28.

[0025] Assume that when the main body 12 is viewed from the tip 12a in the tip view, each secondary relief surface 44 has a first region 44a in which the width C1 in the direction orthogonal to each sub-edge 36 is constant. In this case, each secondary relief surface 44 can stably exhibit the vanishing effect by each secondary relief surface 44 and further improve the surface roughness of the machined surface. Further, when the first region 44a of each secondary relief surface 44 is wider than other regions of each secondary relief surface 44, the vanishing effect by each secondary relief surface 44 can be more stably exhibited, and the surface roughness of the machined surface can be further improved.

[0026] With reference to FIGS. 8 to 11, a method for manufacturing a machined product according to an embodiment will be described. FIGS. 8 to 11 are schematic diagrams for explaining the method for manufacturing a machined product according to the embodiment.

[0027] As shown in FIGS. 8 to 11, the method for manufacturing a machined object according to the present embodiment is a method for manufacturing a machined object M which is a machined workpiece W, and includes a first step, a second step, and a third step. The first step is a step of rotating an end mill 10 as a rotary tool. The second step is a step of bringing the rotating end mill 10 into contact with the workpiece W. The third step is a step of separating the end mill 10 from the workpiece W. And the specific content of the method for manufacturing a machined object according to the present embodiment is as follows.

[0028] As shown in FIGS. 8 and 9, while rotating the end mill 10 in the rotation direction T of the rotation axis S, it is moved in the direction of arrow D1 to approach the workpiece W. Next, as shown in FIG. 10, while bringing the rotating end mill 10 into contact with the workpiece W, it is moved in the direction of arrow D2. As a result, machining of the workpiece W, in other words, face milling is performed. As a result, a machined bottom surface Wf is formed on the workpiece W by the two parent blades 28 and the two child blades 36, and a machined side surface Ws is formed on the workpiece W by the plurality of outer peripheral blades 20.

[0029] Thereafter, as shown in FIG. 11, the end mill 10 is moved in the direction of arrow D3 to separate it from the workpiece W. As a result, the machining of the workpiece W is completed, and a machined object M which is a machined workpiece W can be manufactured. Since the end mill 10 has excellent cutting ability for the reasons described above, a machined object M with excellent machining accuracy can be manufactured.

[0030] When continuing the machining, in a state where the end mill 10 is rotated, the contact of the end mill 10 with different portions of the workpiece W may be repeated. In the present embodiment, the end mill 10 is approaching the workpiece W, but since it is sufficient that the end mill 10 and the workpiece W approach relatively, for example, the workpiece W may be brought closer to the end mill 10. In this regard, the same applies when separating the end mill 10 from the workpiece W.

[0031] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to each of the above-described embodiments. That is, various changes are possible within the scope shown in the present disclosure for the invention according to the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. Also, note that these deformations or modifications are included in the scope of the present disclosure.

Explanation of Reference Numerals

[0032] 10 End mill 12 Main body 12a Tip (first end) 12b Rear end (second end) 14 Cutting portion 16 Shank portion 18 Discharge groove 20 Outer peripheral edge 22 Rake face 24 Relief face 26 Chisel edge 28 Parent edge 30 Parent rake face 32 Parent relief face 34 Corner portion 36 Sub-edge 38 Sub-rake face 40 Sub-relief face 42 Corner portion 44 Second relief face 44a First region 46 Third relief face 48 Gash face S Rotation axis T Rotation direction W Workpiece Wf Machined bottom surface Ws Machined side surface

Claims

1. It extends along the rotation axis from the first end to the second end and has a cylindrical body. The body has a chisel edge located on the first end side and intersecting the rotation axis, a main cutting edge located on the first end side and extending from the chisel edge toward the outer peripheral side, a flat main relief surface adjacent to the main cutting edge behind in the rotation direction of the rotation axis, a sub-cutting edge located on the first end side and extending from a position away from the chisel edge toward the outer peripheral side, and a sub-relief surface adjacent to the sub-cutting edge behind in the rotation direction of the rotation axis. The sub-relief surface has a flat secondary relief surface adjacent to the sub-cutting edge behind in the rotation direction of the rotation axis, and a flat tertiary relief surface adjacent to the secondary relief surface behind in the rotation direction of the rotation axis. When the body is viewed from the tip from the first end, the maximum value of the width of the secondary relief surface in the direction orthogonal to the sub-cutting edge is smaller than the maximum value of the width of the main relief surface in the direction orthogonal to the main cutting edge. The relief angle of the secondary relief surface is smaller than the relief angle of the main relief surface. A rotary tool.

2. The relief angle of the tertiary relief surface is larger than the relief angle of the main relief surface. The rotary tool according to claim 1.

3. The main cutting edge is inclined with respect to the radial direction of the body so as to approach the second end side as it approaches the rotation axis. The rotary tool according to claim 1 or 2.

4. When the body is viewed from the tip from the first end, the secondary relief surface has a first region with a constant width in the direction orthogonal to the sub-cutting edge. The rotary tool according to claim 1 or 2.

5. The first region of the secondary relief surface is wider than other regions on the secondary relief surface. The rotary tool according to claim 4.

6. A step of rotating the rotary tool according to claim 1 or 2, a step of bringing the rotating rotary tool into contact with a workpiece to be machined, and a step of separating the rotary tool from the workpiece to be machined. A method for manufacturing a machined product.

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