Hob cutter assembly, hobbing machine, and hob cutter

Abstract

The present invention provides a hob cutter assembly, hobbing machine, and hob cutter that expand the range of materials that make up the hob cutter and the shank. [Solution] The hob cutter assembly of the present invention comprises a hob cutter extending axially along a central axis, and a shank portion extending axially along the central axis and positioned axially to one side of the hob cutter. The hob cutter and the shank portion are detachably connected axially.

Description

Technical Field

[0001] The present invention relates to a hob cutter assembly, a hob disk, and a hob cutter.

Background Art

[0002] There is known a hob cutting tool used for cutting gears in a gear processing machine, in which a shank and a plurality of cutting teeth are integrally formed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a hob cutting tool, since high durability performance is required for the cutting teeth, generally, the cutting teeth are made of high-strength materials such as cemented carbide and high-speed tool steel. Therefore, in a hob cutting tool in which a shank and a plurality of cutting teeth are integrally formed as described above, the entire hob cutting tool is made of the high-strength material that constitutes the cutting teeth. Therefore, even a shank, which is a part that can be made of a material having a strength smaller than the strength required for the cutting teeth without problem, is made of a high-strength material. Therefore, the options for the materials constituting the cutting teeth and the shank could not be expanded.

[0005] One object of one aspect of the present invention is to provide a hob cutter assembly, a hob disk, and a hob cutter that can expand the options for the materials constituting the hob cutter and the materials constituting the shank portion.

Means for Solving the Problems

[0006] One embodiment of the hob cutter assembly of the present invention comprises a hob cutter extending axially along a central axis, and a shank portion extending axially along the central axis and positioned axially to one side of the hob cutter. The hob cutter and the shank portion are detachably connected in the axial direction.

[0007] One embodiment of the hobbing machine of the present invention comprises the above-described hob cutter assembly and a drive unit for rotating the hob cutter assembly about the central axis.

[0008] One embodiment of the present invention is a hob cutter in which a shank portion is detachably connected to one end on the axial side, and comprises a cylindrical portion extending axially along a central axis, and a cutter portion comprising a plurality of cutting edges protruding radially outward from at least a part of the outer circumferential surface of the cylindrical portion, and surrounding the cylindrical portion from the radially outward side. [Effects of the Invention]

[0009] According to one aspect of the present invention, in a hob cutter assembly, a hob machine, and a hob cutter, the options for materials constituting the hob cutter and the shank portion can be expanded. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a side view of the hobbing machine according to the embodiment. [Figure 2] Figure 2 is a perspective view of the hob slider according to the embodiment. [Figure 3] Figure 3 is a cross-sectional view of the hob cutter assembly of the embodiment. [Figure 4] Figure 4 is a perspective view of the hob cutter assembly of an embodiment. [Figure 5] Figure 5 is a first cross-sectional view illustrating the repair work of the cut portion in the embodiment. [Figure 6] Figure 6 is a second cross-sectional view illustrating the repair work of the cut portion in the embodiment. [Figure 7]Figure 7 is a third cross-sectional view illustrating the repair work of the cut portion in the embodiment. [Figure 8] Figure 8 is a fourth cross-sectional view illustrating the repair work of the cut portion in the embodiment. [Figure 9] Figure 9 is a cross-sectional view of the first modified hob cutter assembly. [Figure 10] Figure 10 is a cross-sectional view of a second modified hob cutter assembly. [Figure 11] Figure 11 is a cross-sectional view of a third modified hob cutter assembly. [Modes for carrying out the invention]

[0011] The following description will refer to the drawings and explain the hob cutter assembly, hob machine, and hob cutter according to embodiments of the present invention. Note that the scope of the present invention is not limited to the following embodiments, and modifications can be made as appropriate within the scope of the technical concept of the present invention. Furthermore, in the following drawings, the scale and number of components may differ from the actual structure for the sake of clarity.

[0012] In the following description, the X, Y, and Z directions are indicated in each figure as appropriate. In this embodiment, the X and Y directions are horizontal and mutually orthogonal. In the following description, the side to which the X-direction arrow points (+X side) is referred to as "one side of the X direction." The side opposite to the side to which the X-direction arrow points (-X side) is referred to as "the other side of the X direction."

[0013] In this embodiment, the Y direction is the direction in which the central axis J of the hob cutter assembly extends. In this embodiment, the central axis J is a virtual axis. In the following description, the Y direction may be referred to as the axial direction. In the following description, the side in which the Y direction arrow points (+Y side) is referred to as the "one axial side". The side opposite to the side in which the Y direction arrow points (-Y side) is referred to as the "other axial side". In the following description, the radial direction centered on the central axis J is simply referred to as the "radial direction". The circumferential direction centered on the central axis J is simply referred to as the "circumferential direction". The circumferential direction is indicated by the arrow θ in each figure.

[0014] In this embodiment, the Z direction is the vertical direction. The Z direction is perpendicular to both the X direction and the Y direction. In the following description, the side to which the arrow in the Z direction points (+Z side) is referred to as the "upper side". The side opposite to the side to which the arrow in the Z direction points (-Z side) is referred to as the "lower side". Note that the definitions of the X direction, the Y direction, and the Z direction do not limit the posture of the hob disk. That is, the X direction and the Y direction may be directions other than the horizontal direction, and the Z direction may be a direction other than the vertical direction.

[0015] <Embodiment> FIG. 1 is a side view of the hob disk 1 of this embodiment. FIG. 2 is a perspective view of the hob slider 20 of this embodiment. The hob disk 1 of this embodiment is a machine tool that manufactures gears by cutting a workpiece W, which is a workpiece, with a hob cutter assembly 30. In the hob disk 1 of this embodiment, a hob cutter assembly 30 is used as a cutting tool. As shown in FIG. 1, the hob disk 1 includes a bed 10, a cutter holding portion 15, a hob cutter assembly 30, and a workpiece holding portion 45.

[0016] The bed 10 is a support base that supports the cutter holding portion 15 and the workpiece holding portion 45. The material constituting the bed 10 is not particularly limited, and it is preferably constituted by rolled steel or cast iron, which is a high-rigidity material. In this embodiment, the bed 10 is installed on the floor of a factory that manufactures gears. The bed 10 has a substantially rectangular parallelepiped shape. On the upper surface of the bed 10, the cutter holding portion 15 and the workpiece holding portion 45 are respectively supported.

[0017] The cutter holding portion 15 is a mechanism that holds the hob cutter assembly 30. The cutter holding portion 15 and the workpiece holding portion 45 are arranged side by side in the X direction. The cutter holding portion 15 is arranged on one side (+X side) in the X direction with respect to the workpiece holding portion 45. The cutter holding portion 15 includes a column 16, a saddle 17, a head portion 18, and a hob slider 20.

[0018] The column 16 is movable in the X direction relative to the bed 10 by a first drive mechanism (not shown). The saddle 17 is attached to the other side of the column 16 facing the X direction (-X side). The saddle 17 is opposite the workpiece holder 45 in the X direction. The saddle 17 is movable in the Z direction relative to the column 16 by a second drive mechanism (not shown).

[0019] The head portion 18 is attached to the saddle 17. The head portion 18 is rotatable about the head axis Ah, which extends in the X direction. The hob slider 20 is attached to the head portion 18. In the X direction, the hob slider 20 is positioned between the head portion 18 and the workpiece holder 45. The hob slider 20 is movable in the Y direction relative to the saddle 17 by a third drive mechanism (not shown). As shown in Figure 2, the hob slider 20 has a base 22, a drive unit 23, and a cutter support 27. That is, the hobbing machine 1 includes a drive unit 23.

[0020] The base 22 is a plate-like structure extending in the axial direction. The plate surface of the base 22 faces the X direction. Although not shown in the illustration, the base 22 is attached to the head portion 18. Thus, the hob slider 20 is attached to the head portion 18.

[0021] Figure 3 is a cross-sectional view of the hob cutter assembly 30 of this embodiment. The drive unit 23 shown in Figure 2 rotates the hob cutter assembly 30 about the central axis J. The drive unit 23 is attached to the other axial side (-Y side) of the hob slider 20. The drive unit 23 has a housing portion 23a. As shown in Figure 3, the drive unit 23 has a cutter mounting portion 24 and a retraction portion 25.

[0022] As shown in Figure 2, the housing section 23a is a substantially cylindrical shape extending in the axial direction. The housing section 23a opens on one side in the axial direction (+Y side). Although not shown in the figure, a part of the cutter mounting section 24 and a part of the retraction section 25 are housed inside the housing section 23a.

[0023] As shown in Figure 3, the cutter mounting portion 24 holds the axially opposite (-Y side) portion of the hob cutter assembly 30. This allows the hob cutter assembly 30 to be attached to the cutter mounting portion 24. The cutter mounting portion 24 is cylindrical, extending axially about the central axis J. More specifically, in this embodiment, the cutter mounting portion 24 is substantially cylindrical, extending axially about the central axis J. The cutter mounting portion 24 is open on both sides in the axial direction. The cutter mounting portion 24 is rotatable about the central axis J. The cutter mounting portion 24 has a first portion 24a and a second portion 24d.

[0024] The first part 24a is substantially cylindrical, extending axially with respect to the central axis J. The first part 24a is the portion of the cutter mounting part 24 on one axial side (+Y side). The first part 24a has a first inner circumferential surface 24b. The first inner circumferential surface 24b is the inner surface of the first part 24a. Viewed from the axial direction, the first inner circumferential surface 24b is substantially circular with respect to the central axis J. The first inner circumferential surface 24b has a tapered shape, with its diameter decreasing towards the other axial side (-Y side).

[0025] The second part 24d is substantially cylindrical in shape, extending axially with respect to the central axis J. The second part 24d is the part on the other axial side of the cutter mounting portion 24. The second part 24d is connected to the first part 24a in the axial direction.

[0026] The retraction section 25 holds the other axial end (-Y side) of the hob cutter assembly 30 and retracts the hob cutter assembly 30 into the cutter mounting section 24. The retraction section 25 is substantially cylindrical in shape and extends axially about the central axis J. Inside the second section 24d, the retraction section 25 holds the other axial end of the hob cutter assembly 30. The retraction force F1, which is the force with which the retraction section 25 retracts the hob cutter assembly 30 toward the other axial direction, is preferably 1000 kg or more and 2000 kg or less. The retraction section 25 is rotatable about the central axis J by a fourth drive mechanism (not shown) located inside the housing section 23a. As a result, the drive unit 23 rotates the hob cutter assembly 30 about the central axis J.

[0027] The cutter support portion 27 shown in Figure 2 supports the axial portion (+Y side) of the hob cutter assembly 30. The cutter support portion 27 supports the hob cutter assembly 30 so that it can rotate about the central axis J. The cutter support portion 27 has a case 27a. As shown in Figure 3, the cutter support portion 27 has a cutter pressing portion 26.

[0028] As shown in Figure 2, the case 27a is substantially cylindrical and extends in the axial direction. Although not shown in the illustration, the case 27a opens on the other axial side (-Y side). Although not shown in the illustration, the cutter pressing part 26 shown in Figure 3 is housed inside the case 27a.

[0029] The cutter pressing portion 26 holds the axial portion (+Y side) of the hob cutter assembly 30. The cutter pressing portion 26 is rotatable together with the hob cutter assembly 30 about the central axis J. The cutter pressing portion 26 is substantially cylindrical in shape and extends axially about the central axis J. The cutter pressing portion 26 is provided with a recess 26a.

[0030] The recess 26a is a recess that extends axially from the surface of the cutter pressing portion 26 facing the other axial side (-Y side). The axial portion of the hob cutter assembly 30 is housed inside the recess 26a. The recess 26a has a third inner circumferential surface 26c. That is, the cutter pressing portion 26 has a third inner circumferential surface 26c. Viewed from the axial direction, the third inner circumferential surface 26c is substantially circular in shape with the central axis J as its center. The third inner circumferential surface 26c has a tapered shape, with the diameter decreasing towards the axial side. A pressing mechanism (not shown) presses the cutter pressing portion 26 to the other axial side. As a result, the cutter pressing portion 26 holds the hob cutter assembly 30 and presses the hob cutter assembly 30 to the other axial side. More specifically, the cutter pressing portion 26 presses the shank portion 37, which will be described later, to the other axial side. The pressing force F2, which is the force exerted by the pressing mechanism (not shown) to press the cutter pressing portion 26 in the other axial direction, is preferably 100 kg or more and 200 kg or less.

[0031] The hob cutter assembly 30 is a cutting tool used to manufacture gears by machining a workpiece W. The hob cutter assembly 30 is detachably attached to the drive unit 23. With the hob cutter assembly 30 attached to the drive unit 23, operating the first, second, and third drive mechanisms (not shown) allows the hob cutter assembly 30 to move together with the drive unit 23 in the X, Y, and Z directions, respectively. Furthermore, with the hob cutter assembly 30 attached to the drive unit 23, operating the fourth drive mechanism (not shown) allows the hob cutter assembly 30 to rotate around its central axis J.

[0032] Figure 4 is a perspective view of the hob cutter assembly 30. The hob cutter assembly 30 is substantially cylindrical in shape and extends in the axial direction. A cutter section 35, composed of multiple blade sections 35a that protrude radially outward, is provided on a part of the outer circumferential surface of the hob cutter assembly 30. When the hob cutter assembly 30 is attached to the drive unit 23 and the cutter support unit 27, the rotation axis of the retraction unit 25 and the central axis J of the hob cutter assembly 30 are arranged coaxially. The configuration of the hob cutter assembly 30 will be described in detail later.

[0033] The workpiece holding section 45 shown in Figure 1 is a mechanism for holding the workpiece W. The workpiece holding section 45 is located on the other side (-X side) in the X direction from the cutter holding section 15. The workpiece holding section 45 faces the cutter holding section 15 with a gap in the X direction. The workpiece holding section 45 includes a rotary table 46, a support column 47, a support head 48, and a center support 49.

[0034] The rotary table 46 is a unit that supports the workpiece W from below. In the X direction, the rotary table 46 is positioned between the cutter holder 15 and the support column 47. The rotary table 46 is mounted on the bed 10 so as to be rotatable about a table axis At that extends in the Z direction. A workpiece support 46a is attached to the upper end of the rotary table 46 to support the workpiece W, which is the gear material, from below.

[0035] The support column 47 is fixed to the upper surface of the bed 10. The support column 47 extends upward from the upper surface of the bed 10. The support column 47 is positioned on the other side in the X direction (-X side) of the rotary table 46.

[0036] The support head 48 is mounted on one side of the support column 47 in the X direction (+X side). The support head 48 is movable in the Z direction relative to the support column 47. The center support 49 is mounted on the support head 48. The center support 49 has a support end 49a that rotatably supports the workpiece W about the table axis At. The support end 49a is located on the table axis At.

[0037] In this embodiment, the workpiece W, which is not shown, is a workpiece. As described above, the hobbing machine 1 manufactures a gear by cutting the workpiece W with the hob cutter assembly 30. Although not shown, the workpiece W is positioned between a workpiece support 46a attached to the rotary table 46 and a support end 49a of the center support 49. The workpiece W is held by the workpiece support 46a and the support end 49a, respectively. When the rotation mechanism (not shown) is operated with the workpiece support 46a and the support end 49a each holding the workpiece W, the workpiece W can be rotated about the table axis At.

[0038] Next, the procedure for machining a workpiece W in the hobbing machine 1 of this embodiment will be described. First, the workpiece W is held by the workpiece support 46a and the support end 49a. Next, the rotation of the workpiece W is started by the rotation mechanism described above, and the rotation of the hob cutter assembly 30 is started by the fourth drive mechanism described above, around the central axis J.

[0039] Next, the first drive mechanism described above moves the column 16 to the other side in the X direction (-X side) relative to the bed 10, bringing the hob cutter assembly 30 into contact with the workpiece W. Then, while rotating both the workpiece W and the hob cutter assembly 30, the position of the hob cutter assembly 30 relative to the workpiece W is gradually changed. As a result, external teeth are formed on the outer surface of the workpiece W, and a gear is manufactured.

[0040] As shown in Figure 4, the hob cutter assembly 30 is cylindrical and extends axially along the central axis J. As described above, the hob cutter assembly 30 is attached to the drive unit 23. As described above, the hob cutter assembly 30 is rotatable about the central axis J by the drive unit 23. As shown in Figure 3, the hob cutter assembly 30 comprises a hob cutter 31, a shank portion 37, a fastening member 39, and a bolt 40.

[0041] The hob cutter 31 is substantially cylindrical in shape and extends axially along the central axis J. The hob cutter 31 is the axially opposite (-Y side) portion of the hob cutter assembly 30. In this embodiment, the hob cutter 31 is made of cemented carbide, which is sintered by mixing tungsten carbide and cobalt as a binder, or high-speed tool steel. In this embodiment, the hob cutter 31 is made of cemented carbide. The hob cutter 31 may also be made of high-speed tool steel. Therefore, the hob cutter 31 has high hardness and high wear resistance. It should be noted that cemented carbide and high-speed tool steel are more expensive materials than carbon steel. When the hob cutter 31 is made of cemented carbide, titanium carbide and tantalum carbide may be added to the cemented carbide. The hob cutter 31 has a cylindrical portion 32 and a cutter portion 35.

[0042] The cylindrical portion 32 is substantially cylindrical in shape and extends axially along the central axis J. The cylindrical portion 32 is open on both sides in the axial direction. As a result, in this embodiment, the hob cutter 31 is hollow. The cylindrical portion 32 has a first cylindrical portion 32a, a second cylindrical portion 32c, a third cylindrical portion 32e, a hob flange 32g, and a through hole 34. Each of the first cylindrical portion 32a, the second cylindrical portion 32c, the third cylindrical portion 32e, and the hob flange 32g is a part of the cylindrical portion 32. The first cylindrical portion 32a, the second cylindrical portion 32c, the hob flange 32g, and the third cylindrical portion 32e are connected axially in this order from one axial side (+Y side) to the other axial side (-Y side).

[0043] The first cylindrical portion 32a is substantially cylindrical in shape and extends axially with respect to the central axis J. The first cylindrical portion 32a is the axial side portion of the cylindrical portion 32. The axial end of the first cylindrical portion 32a is the axial end of the cylindrical portion 32. A cutter portion 35 is provided on the outer circumferential surface of the first cylindrical portion 32a.

[0044] The second cylindrical portion 32c is substantially cylindrical in shape, extending axially with respect to the central axis J. The second cylindrical portion 32c is located on the other axial side of the first cylindrical portion 32a. The second cylindrical portion 32c is connected to the first cylindrical portion 32a in the axial direction. In this embodiment, the outer diameter of the second cylindrical portion 32c is smaller than the outer diameter of the first cylindrical portion 32a.

[0045] The hob flange 32g is approximately annular in shape with the central axis J as its center. The hob flange 32g is positioned on the other axial side of the second cylindrical portion 32c. The hob flange 32g is connected to the second cylindrical portion 32c in the axial direction. The outer diameter of the hob flange 32g is larger than the outer diameter of the second cylindrical portion 32c. The surface of the hob flange 32g facing the other axial side is axially opposite to the cutter mounting portion 24. As described above, the hob cutter assembly 30 is subjected to a retraction force F1, which is a force directed in the other axial direction by the retraction portion 25. Also, as described above, the hob cutter assembly 30 is subjected to a pressing force F2, which is a force directed in the other axial direction by the cutter pressing portion 26. As a result, the hob flange 32g is pressed against the cutter mounting portion 24. Therefore, the hob cutter assembly 30 is supported axially by the cutter mounting portion 24, and the axial position of the hob cutter assembly 30 relative to the drive unit 23 is determined.

[0046] The third cylindrical portion 32e is substantially cylindrical in shape, extending axially with respect to the central axis J. The third cylindrical portion 32e is the portion on the other axial side (-Y side) of the cylindrical portion 32. The other axial end of the third cylindrical portion 32e is the other axial end of the cylindrical portion 32. The third cylindrical portion 32e is located on the other axial side of the hob flange 32g. The third cylindrical portion 32e is connected to the hob flange 32g in the axial direction. In this embodiment, the outer diameter of the third cylindrical portion 32e is smaller than the outer diameter of the hob flange 32g. The third cylindrical portion 32e is located inside the first portion 24a of the cutter mounting portion 24. The third cylindrical portion 32e has a first outer peripheral surface 32f.

[0047] The first outer circumferential surface 32f is the outer circumferential surface of the third cylindrical portion 32e. The first outer circumferential surface 32f is the portion of the outer circumferential surface of the cylindrical portion 32 that includes the end on the other axial side of the cylindrical portion 32. The first outer circumferential surface 32f is located inside the first portion 24a. Viewed from the axial direction, the first outer circumferential surface 32f is substantially circular in shape with the central axis J as the center. The first outer circumferential surface 32f has a tapered shape in which the diameter decreases as it is directed toward the other axial side. As described above, the first inner circumferential surface 24b has a tapered shape in which the diameter decreases as it is directed toward the other axial side. As described above, the hob cutter assembly 30 is subjected to a pulling force F1 and a pressing force F2, which are forces directed toward the other axial side. As a result, the first outer circumferential surface 32f becomes a two-face constrained axis pressed against the first inner circumferential surface 24b, thereby suitably increasing the coaxiality between the hob cutter 31 and the cutter mounting portion 24. Therefore, eccentricity of the cutter portion 35 can be effectively suppressed during the machining of the workpiece W. This allows for a favorable improvement in the tooth profile accuracy of the machined gear.

[0048] The through-hole 34 is a hole that penetrates the cylindrical portion 32 in the axial direction. The through-hole 34 extends axially along the central axis J. As a result, the hob cutter 31 in this embodiment is hollow. Therefore, according to this embodiment, the volume of the hob cutter 31 can be reduced compared to the case where the hob cutter 31 is a solid member. This makes it possible to reduce the weight of the hob cutter 31 and suppress an increase in the manufacturing cost of the hob cutter 31.

[0049] According to this embodiment, the hob cutter 31 has a cylindrical portion 32 that extends axially along the central axis J, and the cylindrical portion 32 has a through hole 34 that penetrates the cylindrical portion 32 axially. Therefore, as described above, the weight of the hob cutter 31 can be reduced, and the increase in the manufacturing cost of the hob cutter 31 can be suppressed. Consequently, the weight of the hob cutter assembly 30 can be reduced, and the increase in the manufacturing cost of the hob cutter assembly 30 can be suppressed.

[0050] The through hole 34 has an insertion hole portion 34a, a first hole portion 34d, a second hole portion 34f, and a third hole portion 34h. Each of the insertion hole portion 34a, the first hole portion 34d, the second hole portion 34f, and the third hole portion 34h is a part of the through hole 34. The insertion hole portion 34a, the first hole portion 34d, the second hole portion 34f, and the third hole portion 34h are connected axially in this order from one axial side (+Y side) to the other axial side (-Y side).

[0051] The insertion hole portion 34a is the portion on one axial side of the through hole 34. The axial end of the insertion hole portion 34a is the axial end of the through hole 34. In the axial direction, the axial end of the insertion hole portion 34a on the other axial side (-Y side) is located on one axial side of the axial center of the first cylindrical portion 32a. The insertion hole portion 34a has a second inner circumferential surface 34b. The second inner circumferential surface 34b is the inner circumferential surface of the insertion hole portion 34a. Viewed from the axial direction, the second inner circumferential surface 34b is approximately circular in shape. The second inner circumferential surface 34b has a tapered shape, with its diameter decreasing towards the other axial side. In other words, the insertion hole portion 34a has a tapered shape, with its diameter decreasing towards the other axial side.

[0052] The first hole 34d is located on the other axial side of the insertion hole 34a. The first hole 34d is connected to the insertion hole 34a in the axial direction. In the axial direction, the other axial end of the first hole 34d is located on the other axial side of the axial center of the first cylindrical portion 32a. In the axial direction, the diameter RI1 of the first hole 34d is approximately constant.

[0053] The second hole 34f is located on the other axial side of the first hole 34d. The second hole 34f is connected to the first hole 34d in the axial direction. In the axial direction, the position of the other axial end of the second hole 34f is approximately the same as the position of the other axial end of the second cylindrical portion 32c. In the axial direction, the diameter RI2 of the second hole 34f is approximately constant. The diameter RI2 of the second hole 34f is smaller than the diameter RI1 of the first hole 34d.

[0054] The third hole 34h is the axially opposite portion of the through hole 34. The axially opposite end of the third hole 34h is the axially opposite end of the through hole 34. The third hole 34h is a hole provided in the hob flange 32g and the third cylindrical portion 32e. The third hole 34h is axially connected to the second hole 34f. In the axial direction, the diameter of the third hole 34h is approximately constant. The diameter of the third hole 34h is smaller than the diameter RI2 of the second hole 34f. A cutter fastening portion 34k is provided in the third hole 34h. The cutter fastening portion 34k is an internal thread provided on the inner circumferential surface of the third hole 34h.

[0055] The cutter section 35 shown in Figure 4 contacts the workpiece W during machining and cuts the workpiece W. The cutter section 35 is composed of a plurality of cutting edges 35a that protrude radially outward from the outer circumferential surface of the first cylindrical section 32a. That is, the cutter section 35 is composed of a plurality of cutting edges 35a that protrude radially outward from at least a part of the outer circumferential surface of the cylindrical section 32. Each cutting edge 35a is arranged in a line along both the axial and circumferential directions. Each cutting edge 35a is provided along the outer circumferential surface of the first cylindrical section 32a over a full circumference. As a result, the cutter section 35 surrounds the cylindrical section 32 from the radial outside.

[0056] As shown in Figure 3, viewed radially, the cutter portion 35 overlaps with the axial portion (+Y side) of the first hole portion 34d and the second hole portion 34f. The ratio of the diameter RI1 of the first hole portion 34d and the diameter RI2 of the second hole portion 34f to the outer diameter R2 of the cutter portion 35 is 50% or more. In other words, in this embodiment, the ratio of the diameters RI1 and RI2 of the portion of the through hole 34 that overlaps with the cutter portion 35 when viewed radially to the outer diameter R2 of the cutter portion 35 is 50% or more. As a result, in this embodiment, the diameter of the through hole 34 can be suitably increased, and the volume of the hob cutter 31 can be suitably reduced. Therefore, the weight of the hob cutter 31 can be suitably reduced, and the increase in the manufacturing cost of the hob cutter 31 can be suitably suppressed. Therefore, the weight of the hob cutter assembly 30 can be suitably reduced, and the increase in the manufacturing cost of the hob cutter assembly 30 can be suitably suppressed. Furthermore, the ratio of diameters RI1 and RI2 to the outer diameter R2 of the cutter portion 35 may be less than 50%.

[0057] As described above, according to this embodiment, the hob cutter 31 is made of cemented carbide or high-speed tool steel. This increases the hardness and wear resistance of the cutter portion 35. Therefore, the durability of the cutter portion 35 can be increased. Consequently, the frequency of repair of the cutter portion 35 and the frequency of replacement of the hob cutter 31 can be reduced. This increases the productivity of gears in the hobbing machine 1.

[0058] The shank portion 37 is substantially cylindrical in shape and extends axially along the central axis J. The shank portion 37 is positioned on one axial side (+Y side) of the hob cutter 31. The hob cutter 31 and the shank portion 37 are detachably connected in the axial direction. More specifically, the shank portion 37 is detachably connected to one axial end of the hob cutter 31. In this embodiment, the hob cutter 31 and the shank portion 37 are made of different materials. In this embodiment, the shank portion 37 is made of, for example, carbon steel. As described above, the hob cutter 31 is made of cemented carbide or high-speed tool steel. Therefore, the materials constituting the hob cutter 31 and the materials constituting the shank portion 37 are different materials. The shank portion 37 has a main body portion 37a and an insertion portion 37d. The shank portion 37 is provided with a hole portion 38.

[0059] The main body portion 37a is substantially cylindrical in shape, extending axially with respect to the central axis J. The main body portion 37a is the axial side (+Y side) of the shank portion 37. The axial end of the main body portion 37a is the axial end of the shank portion 37. In the axial direction, the main body portion 37a is positioned axially to one side of the hob cutter 31. The main body portion 37a has a third outer peripheral surface 37b.

[0060] The third outer circumferential surface 37b is the portion of the outer circumferential surface of the main body portion 37a that includes the end on one side in the axial direction. The third outer circumferential surface 37b is located inside the recess 26a of the cutter pressing portion 26. Viewed from the axial direction, the third outer circumferential surface 37b is substantially circular in shape with the central axis J as the center. The third outer circumferential surface 37b has a tapered shape in which the diameter decreases towards one side in the axial direction. As described above, the third inner circumferential surface 26c has a tapered shape in which the diameter decreases towards one side in the axial direction. As described above, the cutter pressing portion 26 presses the shank portion 37 to the other side in the axial direction (-Y side). As a result, the third outer circumferential surface 37b is pressed against the third inner circumferential surface 26c, which allows for a favorable increase in the coaxiality between the hob cutter 31 and the cutter pressing portion 26. Therefore, eccentricity of the cutter portion 35 can be more favorably suppressed when machining the workpiece W. Therefore, the tooth profile accuracy of the machined gear can be more effectively improved.

[0061] The insertion portion 37d is substantially cylindrical in shape, extending axially with respect to the central axis J. The insertion portion 37d is the axially opposite (-Y side) portion of the shank portion 37. The axially opposite end of the insertion portion 37d is the axially opposite end of the shank portion 37. The insertion portion 37d is positioned axially opposite to the main body portion 37a. The insertion portion 37d is axially connected to the main body portion 37a. The insertion portion 37d is inserted into the through hole 34. The insertion portion 37d has a second outer peripheral surface 37e.

[0062] The second outer circumferential surface 37e is the outer circumferential surface of the insertion portion 37d. The second outer circumferential surface 37e is located inside the through hole 34. Viewed from the axial direction, the second outer circumferential surface 37e is substantially circular in shape with the central axis J as the center. The second outer circumferential surface 37e has a tapered shape in which the diameter decreases as it is directed toward the other side in the axial direction. That is, the outer circumferential surface of the insertion portion 37d has a tapered shape in which the diameter decreases as it is directed toward the other side in the axial direction. As described above, the second inner circumferential surface 34b has a tapered shape in which the diameter decreases as it is directed toward the other side in the axial direction. As described above, the cutter pressing portion 26 presses the shank portion 37 toward the other side in the axial direction. As a result, the second outer circumferential surface 37e is pressed against the second inner circumferential surface 34b. In other words, the outer circumferential surface of the insertion portion 37d comes into contact with the inner circumferential surface of the insertion hole portion 34a. Also, in this embodiment, the shape of the first outer circumferential surface 32f and the shape of the second outer circumferential surface 37e are identical. Therefore, the shape of the first outer surface 32f and the shape of the second inner surface 34b are identical.

[0063] According to this embodiment, the shank portion 37 has an insertion portion 37d that is inserted into the through hole 34, the second outer peripheral surface 37e, i.e. the outer peripheral surface of the insertion portion 37d, has a tapered shape in which the diameter decreases toward the other axial side (-Y side), the through hole 34 has an insertion hole portion 34a that has a tapered shape in which the diameter decreases toward the other axial side, and the second outer peripheral surface 37e is in contact with the second inner peripheral surface 34b, i.e. the inner peripheral surface of the insertion hole portion 34a. This effectively prevents the shank portion 37 from being fastened at an angle to the hob cutter 31. Therefore, the coaxiality between the hob cutter 31 and the shank portion 37 can be effectively increased. This effectively prevents the cutter portion 35 from becoming eccentric during machining of the workpiece W. Therefore, the tooth profile accuracy of the machined gear can be more effectively improved.

[0064] Furthermore, according to this embodiment, the through hole 34 has an insertion hole portion 34a that has a tapered shape, with the diameter decreasing as it moves toward the other side in the axial direction. Therefore, as described above, the coaxiality between the hob cutter 31 and the shank portion 37 can be suitably increased. This makes it possible to more suitably suppress eccentricity of the cutter portion 35 during machining of the workpiece W. Consequently, the tooth profile accuracy of the machined gear can be more suitably improved.

[0065] Furthermore, in this embodiment, as described above, the coaxiality between the hob cutter 31 and the shank portion 37 can be suitably increased by pressing the second outer peripheral surface 37e against the second inner peripheral surface 34b. Therefore, when assembling the shank portion 37 to the hob cutter 31, the work of adjusting the coaxiality between the hob cutter 31 and the shank portion becomes unnecessary. Thus, the work of assembling the shank portion 37 to the hob cutter 31 can be simplified.

[0066] Viewed radially, the insertion portion 37d overlaps with the portion of the cutter portion 35 on one axial side (+Y side). In other words, according to this embodiment, viewed radially, a part of the shank portion 37 overlaps with at least a part of the cutter portion 35. Therefore, compared to the case where the shank portion 37 is positioned on one axial side of the cutter portion 35, it is easier to increase the contact area between the second outer peripheral surface 37e and the second inner peripheral surface 34b. As a result, it is easier to increase the coaxiality between the hob cutter 31 and the shank portion 37. This makes it possible to more effectively suppress eccentricity of the cutter portion 35 during machining of the workpiece W. Consequently, the tooth profile accuracy of the machined gear can be more effectively improved.

[0067] The hole 38 is a recess that extends axially from the surface of the shank portion 37 facing the other axial side (-Y side) toward one axial side. Viewed from the axial direction, the hole 38 is substantially circular in shape with the central axis J as its center. In this embodiment, the hole 38 is a hole that penetrates the shank portion 37 in the axial direction. The hole 38 does not necessarily have to penetrate the shank portion 37 in the axial direction. The diameter of the hole 38 is substantially the same as the diameter of the third hole 34h of the through hole 34. The hole 38 has a shank fastening portion 38a.

[0068] The shank fastening portion 38a is an internal thread provided on the inner circumferential surface of the hole portion 38. In this embodiment, the shank fastening portion 38a is provided in the portion of the hole portion 38 that overlaps with the insertion portion 37d when viewed from the radial direction. Therefore, in this embodiment, the shank fastening portion 38a is located inside the hob cutter 31. Note that one axial end of the shank fastening portion 38a may be located axially to one side of the hob cutter 31 when viewed from the radial direction.

[0069] The fastening member 39 is a substantially cylindrical bolt extending axially with respect to the central axis J. The fastening member 39 is positioned inside the through hole 34. The diameter of the insertion hole 34a, the diameter of the first hole 34d RI1, and the diameter of the second hole 34f RI2 are all larger than the outer diameter R1 of the fastening member 39. In other words, according to this embodiment, the diameter of at least a portion of the through hole 34 is larger than the outer diameter R1 of the fastening member 39. Therefore, the diameter of the through hole 34 can be suitably increased compared to the case where the overall diameter of the through hole 34 and the outer diameter R1 of the fastening member 39 are the same. This allows for a more favorable reduction in the volume of the hob cutter 31. As a result, the weight of the hob cutter 31 can be more favorably reduced, and the increase in the manufacturing cost of the hob cutter 31 can be more favorably suppressed. Consequently, the weight of the hob cutter assembly 30 can be more favorably reduced, and the increase in the manufacturing cost of the hob cutter assembly 30 can be more favorably suppressed.

[0070] The other axial side (-Y side) of the fastening member 39 is fastened to the one axial side (+Y side) of the cutter fastening portion 34k. As a result, the other axial side of the fastening member 39 is fastened to the inner circumferential surface of the through hole 34. The one axial side of the fastening member 39 is fastened to the shank fastening portion 38a. That is, the fastening member 39 is fastened to the shank fastening portion 38a. As a result, the one axial side of the fastening member 39 is fastened to the inner circumferential surface of the hole portion 38. In this way, the fastening member 39 fastens the hob cutter 31 and the shank portion 37 to each other.

[0071] According to this embodiment, the hob cutter assembly 30 includes a fastening member 39 that fastens the hob cutter 31 and the shank portion 37 together. The shank portion 37 is provided with a recessed hole 38 on one axial side (+Y side), and the other axial side (-Y side) portion of the fastening member 39 is fastened to the inner circumferential surface of the through hole 34, while the axial side portion of the fastening member 39 is fastened to the inner circumferential surface of the hole 38. As a result, the hob cutter 31 and the shank portion 37 are fastened together by the fastening member 39, as described above. Therefore, when attaching the hob cutter assembly 30 to the cutter mounting portion 24, it is possible to prevent either the hob cutter 31 or the shank portion 37 from falling. Thus, the work of attaching the hob cutter assembly 30 to the cutter mounting portion 24 can be simplified.

[0072] The bolt 40 is located inside the cutter mounting portion 24. Preferably, the bolt 40 is a pull stud bolt. In this embodiment, the bolt 40 is a pull stud bolt. The bolt 40 is tightened into the other axial side (-Y side) portion of the cutter fastening portion 34k. In this way, the bolt 40 is fastened to the hob cutter 31. The pull-in portion 25 holds the head of the bolt 40. The pull-in portion 25 applies a pull-in force F1 to the bolt 40 that is directed in the other axial direction. As a result, as described above, a pull-in force F1 directed in the other axial direction is applied to the hob cutter assembly 30, and the hob cutter assembly 30 is attached to the cutter mounting portion 24.

[0073] Next, the procedure for repairing the cutter portion 35 of the hob cutter 31 will be described. The cutter portion 35 is repaired when the wear amount of each blade portion 35a reaches a predetermined wear amount, or when a coating layer (not shown) formed on the surface of each blade portion 35a peels off, etc. In this specification, "worker, etc." includes the worker and assembly equipment, etc. that repair the cutter portion 35. Each operation for repairing the cutter portion 35 may be performed by the worker alone, by the assembly equipment alone, or by the worker and the assembly equipment together.

[0074] As shown in Figure 5, the operator first removes the cutter pressing section 26 and the retraction section 25 from the hob cutter assembly 30. This allows the operator to remove the hob cutter assembly 30 from the cutter mounting section 24, as shown in Figure 6. Next, the operator removes the bolt 40 from the hob cutter 31 by rotating the bolt 40 circumferentially relative to the hob cutter 31, as shown in Figure 7. Next, the operator removes the shank section 37 and the fastening member 39 from the hob cutter 31 by rotating the shank section 37 circumferentially relative to the hob cutter 31, as shown in Figure 6. In other words, the hob cutter 31 and the shank section 37 are detachably connected in the axial direction.

[0075] Next, although not shown in the diagram, the operator restores the tip shape of each blade portion 35a of the cutter portion 35 to a pointed shape by polishing or the like. Next, the operator forms a coating layer (not shown) on the surface of each blade portion 35a. As the material constituting the coating layer, for example, a high-hardness material such as titanium nitride and titanium carbide, which are titanium-based ceramics, can be used. In this embodiment, the coating layer is formed by physical vapor deposition (PVD) using the vapor deposition apparatus 90 shown in Figure 8. The operator houses a plurality of hob cutters 31 inside the vapor deposition apparatus 90 and forms a coating layer on the surface of each hob cutter 31. At this time, each hob cutter 31 is positioned with its insertion hole portion 34a facing downwards, and the third cylindrical portion 32e of the hob cutter 31 positioned lower down is inserted into the insertion hole portion 34a. This allows the plurality of hob cutters 31 to be stacked vertically. After the operators form a coating layer on the surface of each hob cutter 31, they remove each hob cutter 31 from the vapor deposition apparatus 90, completing the repair work on the cutter portion 35 of each hob cutter 31. The repaired hob cutter 31 is then reconnected to the shank portion 37 and used for cutting the workpiece W on the hobbing machine 1.

[0076] According to this embodiment, as described above, the shape of the first outer surface 32f and the shape of the second outer surface 37e, that is, the shape of the outer surface of the insertion portion 37d, are the same. Therefore, as described above, the shape of the first outer surface 32f and the shape of the second inner surface 34b are the same. Consequently, when simultaneously forming a coating layer on the cutter portions 35 of multiple hob cutters 31, the first outer surface 32f of one hob cutter 31 can be brought into surface contact with the second inner surface 34b of another hob cutter 31 by inserting the third cylindrical portion 32e of another hob cutter 31 into the insertion hole portion 34a of one hob cutter 31 from below. This makes it possible to stack multiple hob cutters 31 vertically and make them self-supporting. Therefore, it is possible to increase the number of hob cutters 31 that can be housed inside the vapor deposition apparatus 90 while suppressing an increase in the horizontal area of ​​the vapor deposition apparatus 90. Consequently, the work efficiency for repairing the cutter portions 35 can be suitably improved.

[0077] Furthermore, in this embodiment, the first outer circumferential surface 32f, which contacts the cutter mounting portion 24, and the second inner circumferential surface 34b, which contacts the shank portion 37, make surface contact with each other when forming the coating layer. Therefore, it is possible to suppress the formation of a coating layer on each of the first outer circumferential surface 32f and the second inner circumferential surface 34b. As a result, in this embodiment, it is not necessary to mask each of the first outer circumferential surface 32f and the second inner circumferential surface 34b with metal foil or the like in order to suppress the formation of a coating layer on each of the first outer circumferential surface 32f and the second inner circumferential surface 34b. Consequently, the number of work steps required to form a coating layer on the cutter portion 35 can be suitably reduced.

[0078] Furthermore, in this embodiment, as described above, multiple hob cutters 31 can be stacked vertically and made self-supporting. Therefore, for example, it is not necessary to pass a rod-shaped member through the through holes 34 of the multiple hob cutters 31 in the axial direction to stack the multiple hob cutters 31 vertically. Consequently, the number of work steps required to form the coating layer on the cutter section 35 can be more effectively reduced.

[0079] According to this embodiment, the hob cutter assembly 30 comprises a hob cutter 31 extending axially along the central axis J, and a shank portion 37 extending axially along the central axis J and positioned on one axial side (+Y side) of the hob cutter 31, with the hob cutter 31 and the shank portion 37 being detachably connected axially. In the hob cutter assembly 30, high durability is required for the cutter portion 35, so generally, the cutter portion 35 is made of a high-strength material such as cemented carbide. Therefore, if the hob cutter assembly 30 is an integrated structure, the entire hob cutter assembly 30 is made of the high-strength material that makes up the cutter portion 35. Consequently, the shank portion 37, which can be made of a material with less strength than the strength required for the cutter portion 35, is also made of a high-strength material. In contrast, in this embodiment, the hob cutter 31 and the shank portion 37 can be made into separate components, allowing the hob cutter 31 and the shank portion 37 to be constructed from different materials. Therefore, the range of materials that can be used to construct the hob cutter 31 and the shank portion 37 can be expanded. This allows the hob cutter 31 and the shank portion 37 to be constructed from the most suitable materials.

[0080] According to this embodiment, the material constituting the hob cutter 31 and the material constituting the shank portion 37 are different materials. Therefore, as described above, the hob cutter 31 can be made of a high-strength material such as cemented carbide or high-speed tool steel, which has high wear resistance, and the shank portion 37 can be made of carbon steel, which is a lower-cost material than cemented carbide, etc. This suppresses an increase in the frequency of repairing the cutter portion 35 and suppresses an increase in the manufacturing cost of the shank portion 37. Therefore, the productivity of gears in the hobbing machine 1 can be increased and the manufacturing cost of the hob cutter assembly 30 can be suppressed.

[0081] According to this embodiment, the hob cutter 31 is composed of a plurality of cutting edges 35a that protrude radially outward from at least a part of the outer circumferential surface of the cylindrical portion 32, and also has a cutter portion 35 that surrounds the cylindrical portion 32 from the radial outside. Therefore, in this embodiment, the hob cutter 31 has a cutter portion 35 that cuts the workpiece W, and the shank portion 37 does not have a cutter portion 35. As a result, the shank portion 37 can be made of a material that is lower in strength and lower in cost than the high-strength material such as cemented carbide that constitutes the hob cutter 31, such as carbon steel. This makes it possible to suppress an increase in the manufacturing cost of the shank portion 37 compared to the case in which the shank portion 37 is made of a high-strength material such as cemented carbide. Therefore, it is possible to more effectively suppress an increase in the manufacturing cost of the hob cutter assembly 30.

[0082] According to this embodiment, the hobbing machine 1 comprises a hob cutter assembly 30 and a drive unit 23 that rotates the hob cutter assembly 30 about a central axis J. As described above, in the hob cutter assembly 30 of this embodiment, the second outer peripheral surface 37e of the shank portion 37 is in contact with the second inner peripheral surface 34b of the hob cutter 31, so that the coaxiality between the hob cutter 31 and the shank portion 37 can be suitably increased. As a result, when the hob cutter assembly 30 is rotated about the central axis J by the drive unit 23 during machining of the workpiece W, eccentricity of the cutter portion 35 can be suitably suppressed. Therefore, the tooth profile accuracy of the machined gear can be suitably increased.

[0083] According to this embodiment, the hob cutter 31 is a hob cutter 31 to which a shank portion 37 is detachably connected to one end on the axial side (+Y side), and has a cylindrical portion 32 extending axially along the central axis J, and a cutter portion 35 which surrounds the cylindrical portion 32 from the radial outside, and is composed of a plurality of cutting edges 35a that protrude radially outward from at least a part of the outer circumferential surface of the cylindrical portion 32. Therefore, as described above, the selection of materials for the hob cutter 31 and the shank portion 37 can be expanded. Thus, the hob cutter 31 and the shank portion 37 can each be made of the optimal material.

[0084] <First variation> Figure 9 is a cross-sectional view of the hob cutter assembly 130 of this modified example. In the following description, components identical to those in the above-described embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0085] As shown in Figure 9, the hob cutter assembly 130 of the hob machine 101 in this modified example is cylindrical in shape and extends axially along the central axis J. The hob cutter assembly 130 comprises a hob cutter 31, a shank portion 137, a fastening member 139, and a bolt 40.

[0086] The shank portion 137 is substantially cylindrical in shape and extends axially along the central axis J. The hob cutter 31 and the shank portion 137 are detachably connected in the axial direction. The materials constituting the hob cutter 31 and the materials constituting the shank portion 137 are different from each other. The shank portion 137 has a main body portion 37a and an insertion portion 37d. The shank portion 137 is provided with a hole portion 138.

[0087] The hole 138 is a recess that extends axially from the surface of the shank portion 137 facing the other axial side (-Y side) toward one axial side. Viewed from the axial direction, the hole 138 is approximately circular in shape with the central axis J as its center. In this modified example, the hole 138 is a hole that penetrates the shank portion 137 in the axial direction. The hole 138 does not necessarily have to penetrate the shank portion 137 in the axial direction. The hole 138 has a shank fastening portion 138a.

[0088] The shank fastening portion 138a is an internal thread provided on the inner circumferential surface of the hole portion 138. A fastening member 139 is fastened to the shank fastening portion 138a. In this modified example, the shank fastening portion 138a spans the inner circumferential surface of the main body portion 37a and the inner circumferential surface of the insertion portion 37d. In the axial direction, one axial end (+Y side) of the shank fastening portion 138a is located one axial side of the hob cutter 31. That is, in this modified example, at least a part of the shank fastening portion 138a is located one axial side of the hob cutter 31. The other configurations of the shank portion 137 in this modified example are the same as the other configurations of the shank portion 37 in the above-described embodiment.

[0089] The fastening member 139 is a substantially cylindrical bolt extending axially with respect to the central axis J. The other axial side (-Y side) of the fastening member 139 is tightened into the axial side (+Y side) of the cutter fastening portion 34k. The axial side (+Y side) of the fastening member 139 is tightened into the shank fastening portion 138a. In this way, the fastening member 139 fastens the hob cutter 31 and the shank portion 137 together. In this modified example, the axial end of the fastening member 139 is located axially to one side of the hob cutter 31. The other configurations of the fastening member 139 in this modified example are the same as the other configurations of the fastening member 39 in the above-described embodiment. The other configurations of the hob cutter assembly 130 in this modified example are the same as the other configurations of the hob cutter assembly 30 in the above-described embodiment. The other configurations of the hobbing machine 101 in this modified example are the same as the other configurations of the hobbing machine 1 in the embodiment described above.

[0090] According to this modified example, the hole 138 has a shank fastening portion 138a to which the fastening member 139 is fastened, and at least a part of the shank fastening portion 138a is located axially to one side (+Y side) of the hob cutter 31. Therefore, compared to a configuration in which the entire shank fastening portion 138a overlaps with the hob cutter 31 when viewed radially, the axial dimension of the shank fastening portion 138a can be increased. This allows for a wider contact area between the fastening member 139 and the shank portion 137, thereby more favorably increasing the coaxiality between the fastening member 139 and the shank portion 137. Consequently, the coaxiality between the hob cutter 31 and the shank portion 137 can be more favorably increased. This makes it more favorably possible to suppress eccentricity of the cutter portion 35 during machining of the workpiece W. Consequently, the tooth profile accuracy of the machined gear can be more favorably increased.

[0091] Furthermore, in this modified example, the hob cutter 31 and the shank portion 137 are detachably connected in the axial direction. Therefore, similar to the embodiment described above, the range of materials that can be used to construct the hob cutter 31 and the shank portion 137 can be expanded.

[0092] <Second variation> Figure 10 is a cross-sectional view of the hob cutter assembly 230 of this modified example. In the following description, components identical to those in the above-described embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0093] As shown in Figure 10, the hob cutter assembly 230 of the hob machine 201 in this modified example is cylindrical in shape and extends axially along the central axis J. The hob cutter assembly 230 comprises a hob cutter 31, a shank portion 237, a fastening member 39, and a bolt 40.

[0094] The shank portion 237 is substantially cylindrical in shape and extends axially along the central axis J. The hob cutter 31 and the shank portion 237 are detachably connected in the axial direction. The materials constituting the hob cutter 31 and the materials constituting the shank portion 237 are different from each other. The shank portion 237 has a main body portion 37a, an insertion portion 37d, and a flange portion 237g. The shank portion 237 is provided with a hole portion 38.

[0095] The flange portion 237g protrudes radially outward from the outer circumferential surface of the main body portion 37a. Viewed from the axial direction, the flange portion 237g is an annular shape surrounding the central axis J. More specifically, viewed from the axial direction, the flange portion 237g is a substantially circular annular shape centered on the central axis J. Viewed from the axial direction, the flange portion 237g may also have other shapes, such as a rectangular annular shape surrounding the central axis J. The flange portion 237g is provided on the outer circumferential surface of the main body portion 37a on the other axial side (-Y side). The flange portion 237g is in axial contact with the outer surface of the hob cutter 31 facing one axial side (+Y side). As described above, the cutter pressing portion 26 presses the shank portion 237 on the other axial side. Therefore, the flange portion 237g is pressed against the surface of the hob cutter 31 facing one axial side. The other configurations of the shank portion 237 in this modified example are the same as the other configurations of the shank portion 37 in the above-described embodiment. The other configurations of the hob cutter assembly 230 in this modified example are the same as the other configurations of the hob cutter assembly 30 in the above-described embodiment. The other configurations of the hobbing machine 201 in this modified example are the same as the other configurations of the hobbing machine 1 in the above-described embodiment.

[0096] In this modified example, the shank portion 237 protrudes radially outward and has an annular flange portion 237g surrounding the central axis J, and the flange portion 237g contacts the outer surface of the hob cutter 31 facing one axial side (+Y side) in the axial direction. Therefore, in this modified example, in addition to the contact between the second outer peripheral surface 37e of the shank portion 37 and the second inner peripheral surface 34b of the hob cutter 31, the flange portion 237g and the hob cutter 31 can be made to contact in the axial direction. This makes it possible to more effectively suppress the shank portion 237 from being fastened at an angle to the hob cutter 31. As a result, the coaxiality between the hob cutter 31 and the shank portion 237 can be more effectively increased. As a result, eccentricity of the cutter portion 35 during machining of the workpiece W can be more effectively suppressed. Therefore, the tooth profile accuracy of the machined gear can be more effectively improved.

[0097] Furthermore, in this modified example, the hob cutter 31 and the shank portion 237 are detachably connected in the axial direction. Therefore, similar to the embodiment described above, the selection of materials for the hob cutter 31 and the shank portion 237 can be expanded.

[0098] <Third variation> Figure 11 is a cross-sectional view of the hob cutter assembly 330 of this modified example. In the following description, components identical to those in the above-described embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0099] As shown in Figure 11, the hob cutter assembly 330 of the hob machine 301 in this modified example is cylindrical in shape and extends axially along the central axis J. The hob cutter assembly 330 comprises a hob cutter 331, a shank portion 37, a fastening member 39, a bolt 40, and a connecting member 342.

[0100] The hob cutter 331 is substantially cylindrical in shape and extends axially along the central axis J. The hob cutter 331 has a cylindrical portion 32 and a cutter portion 35. The cylindrical portion 32 is substantially cylindrical in shape and extends axially along the central axis J. The cylindrical portion 32 has a first cylindrical portion 32a, a second cylindrical portion 32c, a third cylindrical portion 32e, a hob flange 32g, and a through hole 334.

[0101] The through hole 334 is a hole that penetrates the cylindrical portion 32 in the axial direction. The through hole 334 has an insertion hole portion 334a, a first hole portion 34d, a second hole portion 34f, and a third hole portion 34h. The insertion hole portion 334a is the portion on one axial side of the through hole 334. The axial end of the insertion hole portion 334a is the axial end of the through hole 334. The insertion hole portion 334a has a second inner circumferential surface 334b. The second inner circumferential surface 334b ​​is the inner circumferential surface of the insertion hole portion 334a. When viewed from the axial direction, the second inner circumferential surface 334b ​​is approximately circular in shape. In this modified example, the diameter of the second inner circumferential surface 334b ​​is constant in the axial direction. That is, in this modified example, the diameter of the insertion hole portion 334a is constant in the axial direction. The other configurations of the hob cutter 331 in this modified example are the same as those of the hob cutter 31 in the embodiment described above.

[0102] The connecting member 342 is substantially annular in shape and extends axially along the central axis J. The connecting member 342 is positioned between the hob cutter 331 and the shank portion 37. In this embodiment, the connecting member 342 is made of metal. The connecting member 342 has a connecting portion 342a and an annular portion 342e.

[0103] The connecting portion 342a is annular in shape, extending axially along the central axis J. In this embodiment, the connecting portion 342a is substantially annular in shape, extending axially with respect to the central axis J. The connecting portion 342a is located inside the insertion hole portion 334a. The connecting portion 342a has a fourth outer circumferential surface 342b and a fourth inner circumferential surface 342c.

[0104] The fourth outer surface 342b is the outer surface of the connecting portion 342a. The fourth outer surface 342b is located inside the insertion hole portion 334a. Viewed from the axial direction, the fourth outer surface 342b is substantially circular in shape with the central axis J as its center. In the axial direction, the diameter of the fourth outer surface 342b is constant. That is, in the axial direction, the diameter of the outer surface of the connecting portion 342a is constant. The fourth outer surface 342b, i.e., the outer surface of the connecting portion 342a, is in radial contact with the second inner surface 334b, i.e., the inner surface of the insertion hole portion 334a. This determines the radial position of the connecting member 342 relative to the hob cutter 331 and allows for a favorable increase in the coaxiality between the connecting member 342 and the hob cutter 331.

[0105] The fourth inner surface 342c is the inner surface of the connecting portion 342a. The fourth inner surface 342c has a tapered shape, with its diameter decreasing as it is directed toward the other axial side (-Y side). Therefore, the inner surface of the connecting portion 342a has a tapered shape, with its diameter decreasing as it is directed toward the other axial side.

[0106] The annular portion 342e is approximately circular with respect to the central axis J. The annular portion 342e is positioned on one axial side (+Y side) of the connecting portion 342a. The annular portion 342e is connected to the connecting portion 342a in the axial direction. The annular portion 342e is positioned on one axial side of the hob cutter 331. The annular portion 342e is in axial contact with the outer surface of the hob cutter 331 that faces one axial side (+Y side). The annular portion 342e is pressed against the surface of the hob cutter 331 that faces one axial side by the cutter pressing portion 26 via the shank portion 37. This determines the axial position of the connecting member 342 relative to the hob cutter 331 and allows for a more favorable increase in the coaxiality between the connecting member 342 and the hob cutter 331.

[0107] In this modified example, the hob cutter 331 and the shank portion 37 are detachably connected axially via a connecting member 342. The shank portion 37 has a main body portion 37a and an insertion portion 37d. The insertion portion 37d is inserted into the through hole 34. The insertion portion 37d is also inserted into the connecting member 342. As described above, the second outer peripheral surface 37e, i.e., the outer peripheral surface of the insertion portion 37d, has a tapered shape with a smaller diameter towards the other axial direction. The second outer peripheral surface 37e contacts the fourth inner peripheral surface 342c. As described above, the cutter pressing portion 26 presses the shank portion 37 to the other axial direction. As a result, the second outer peripheral surface 37e is pressed against the fourth inner peripheral surface 342c. Therefore, it is possible to more effectively suppress the shank portion 37 from being fastened at an angle to the connecting member 342. Therefore, the coaxiality between the connecting member 342 and the shank portion 37 can be suitably increased. The configuration of the hob cutter assembly 330 in this modified example is the same as the configuration of the hob cutter assembly 30 in the above-described embodiment. The other configurations of the hobbing machine 301 in this modified example are the same as the other configurations of the hobbing machine 1 in the above-described embodiment.

[0108] According to this modified example, the hob cutter assembly 330 includes a connecting member 342 having an annular connecting portion 342a extending axially along the central axis J, the shank portion 37 has an insertion portion 37d that is inserted into the through hole 334, the outer circumferential surface of the insertion portion 37d has a tapered shape in which the diameter decreases toward the other axial side (-Y side), the inner circumferential surface of the connecting portion 342a has a tapered shape in which the diameter decreases toward the other axial side, the diameter of the outer circumferential surface of the connecting portion 342a is constant in the axial direction, the through hole 334 has an insertion hole portion 334a with a constant diameter in the axial direction, the outer circumferential surface of the connecting portion 342a is in contact with the inner circumferential surface of the insertion hole portion 334a, and the outer circumferential surface of the insertion portion 37d is in contact with the inner circumferential surface of the connecting portion 342a. Therefore, as described above, the coaxiality between the connecting member 342 and the shank portion 37 can be suitably increased, and as described above, the coaxiality between the connecting member 342 and the hob cutter 331 can be suitably increased. As a result, in this modified example, the coaxiality between the hob cutter 331 and the shank portion 37 can be suitably increased via the connecting member 342. Therefore, eccentricity of the cutter portion 35 can be more suitably suppressed when machining the workpiece W. Consequently, the tooth profile accuracy of the machined gear can be suitably increased.

[0109] Furthermore, in this modified example, as described above, the diameter of the insertion hole 334a is constant in the axial direction. Therefore, compared to, for example, the case where the inner circumferential surface of the insertion hole 334a has a tapered shape with a smaller diameter towards the other side in the axial direction, the number of man-hours required to form the through hole 334 in the hob cutter 331 can be reduced. Thus, an increase in the number of man-hours required to manufacture the hob cutter assembly 330 can be effectively suppressed.

[0110] Furthermore, in this modified example, the hob cutter 331 and the shank portion 37 are detachably connected in the axial direction. Therefore, similar to the embodiment described above, the range of materials that can be used to construct the hob cutter 331 and the shank portion 37 can be expanded.

[0111] Although embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments.

[0112] The materials constituting the hob cutter and the shank may be the same material. In this case, it is preferable that the hob cutter and the shank be made of a high-hardness material such as cemented carbide, in order to improve the durability of the cutting portion.

[0113] Furthermore, this technology can be configured as follows: (1) A hob cutter assembly comprising a hob cutter extending axially along a central axis and a shank portion extending axially along the central axis and positioned axially to one side of the hob cutter, wherein the hob cutter and the shank portion are detachably connected in the axial direction. (2) The hob cutter assembly according to (1), wherein the material constituting the hob cutter and the material constituting the shank portion are different materials from each other. (3) The hob cutter assembly according to (1) or (2), wherein the hob cutter has a cylindrical portion extending axially along the central axis, and the cylindrical portion has a through hole that penetrates the cylindrical portion axially. (4) The hob cutter assembly according to (3), further comprising a fastening member for fastening the hob cutter and the shank portion to each other, wherein the shank portion is provided with a recessed hole on one side in the axial direction, the other side of the fastening member in the axial direction is fastened to the inner circumferential surface of the through hole, and the other side of the fastening member in the axial direction is fastened to the inner circumferential surface of the hole. (5) The hob cutter assembly according to (4), wherein the hole has a shank fastening portion to which the fastening member is fastened, and at least a portion of the shank fastening portion is located on one axial side of the hob cutter. (6) The hob cutter assembly according to (4) or (5), wherein the diameter of at least a portion of the through hole is larger than the outer diameter of the fastening member. (7) The hob cutter assembly according to any one of (3) to (6), wherein the shank portion has an insertion portion that is inserted into the through hole, the outer circumferential surface of the insertion portion has a tapered shape in which the diameter decreases toward the other axial direction, the through hole has an insertion hole portion that has a tapered shape in which the diameter decreases toward the other axial direction, and the outer circumferential surface of the insertion portion is in contact with the inner circumferential surface of the insertion hole portion. (8) The hob cutter assembly according to (7), wherein the shank portion protrudes radially outward and has an annular flange portion surrounding the central axis, and the flange portion contacts in the axial direction with the outer surface of the hob cutter facing one side in the axial direction. (9) The hob cutter assembly according to any one of (3) to (6), comprising a connecting member having an annular connecting portion extending axially along the central axis, wherein the shank portion has an insertion portion that is inserted into the through hole, the outer circumferential surface of the insertion portion is tapered in that the diameter decreases toward the other side in the axial direction, the inner circumferential surface of the connecting portion is tapered in that the diameter decreases toward the other side in the axial direction, the diameter of the outer circumferential surface of the connecting portion is constant in the axial direction, the through hole has an insertion hole portion of constant diameter, the outer circumferential surface of the connecting portion is in contact with the inner circumferential surface of the insertion hole portion, and the outer circumferential surface of the insertion portion is in contact with the inner circumferential surface of the connecting portion. (10) The hob cutter assembly according to (9), wherein the first outer surface of the cylindrical portion, which includes the end of the cylindrical portion on the other axial side, has a tapered shape with a smaller diameter toward the other axial side, and the shape of the first outer surface is the same as the shape of the outer surface of the insertion portion. (11) The hob cutter assembly according to any one of (3) to (10), wherein the hob cutter is composed of a plurality of cutting edges protruding radially outward from at least a portion of the outer circumferential surface of the cylindrical portion, and has a cutter portion surrounding the cylindrical portion from the radially outward side. (12) The hob cutter assembly according to (11), wherein, viewed radially, a portion of the shank portion overlaps with at least a portion of the cutter portion. (13) A hobbing machine comprising a hob cutter assembly as described in any one of (1) to (12), and a drive unit for rotating the hob cutter assembly about the central axis. (14) A hob cutter having a shank portion detachably connected to one end on the axial side, comprising: a cylindrical portion extending axially along a central axis; and a cutter portion comprising a plurality of cutting edges protruding radially outward from at least a part of the outer circumferential surface of the cylindrical portion, and surrounding the cylindrical portion from the radially outward side. (15) The hob cutter according to (14), wherein the cylindrical portion has a through hole that penetrates the cylindrical portion in the axial direction. (16) The hob cutter according to (15), wherein the through hole has an insertion hole portion that is tapered in shape, with the diameter decreasing as it is directed toward the other side in the axial direction. (17) A hob cutter according to any one of items (14) to (16), made of cemented carbide or high-speed tool steel. [Explanation of symbols]

[0114] 1,101,201,301…Hobbing machine, 23…Drive unit, 30,130,230,330…Hob cutter assembly, 31,331…Hob cutter, 32…Cylindrical part, 32f…First outer surface, 34,334…Through hole, 34a,334a…Insertion hole, 35…Cutter part, 35a…Blade part, 37,137,237…Shank part, 37d…Insertion part, 38,138…Hole part, 38a,138a…Shank fastening part, 39,139…Fastening member, 237g…Flange part, 342…Connecting member, J…Central axis

Claims

1. A hob cutter extending axially along the central axis, A shank portion extending axially along the aforementioned central axis and positioned on one axial side of the hob cutter, Equipped with, A hob cutter assembly in which the hob cutter and the shank are detachably connected in the axial direction.

2. The hob cutter assembly according to claim 1, wherein the material constituting the hob cutter and the material constituting the shank portion are different materials from each other.

3. The hob cutter has a cylindrical portion that extends axially along the central axis, The hob cutter assembly according to claim 1, wherein the cylindrical portion has a through hole that penetrates the cylindrical portion in the axial direction.

4. The hob cutter and the shank portion are fastened together by a fastening member, The shank portion is provided with a recessed hole on one side in the axial direction. The other axial portion of the fastening member is fastened to the inner circumferential surface of the through hole. The hob cutter assembly according to claim 3, wherein the portion of the fastening member on one axial side is fastened to the inner circumferential surface of the hole.

5. The aforementioned hole has a shank fastening portion to which the fastening member is fastened. The hob cutter assembly according to claim 4, wherein at least a portion of the shank fastening portion is located on one axial side of the hob cutter.

6. The hob cutter assembly according to claim 4, wherein the diameter of at least a portion of the through hole is larger than the outer diameter of the fastening member.

7. The shank portion has an insertion portion that is inserted into the through hole, The outer circumferential surface of the insertion portion has a tapered shape, with the diameter decreasing as it is directed toward the other side in the axial direction. The through hole has an insertion hole portion that has a tapered shape, with the diameter decreasing as it is directed toward the other side in the axial direction. The hob cutter assembly according to any one of claims 3 to 6, wherein the outer circumferential surface of the insertion portion is in contact with the inner circumferential surface of the insertion hole portion.

8. The shank portion protrudes radially outward and has an annular flange portion surrounding the central axis. The hob cutter assembly according to claim 7, wherein the flange portion contacts in the axial direction with one side of the outer surface of the hob cutter.

9. The connecting member comprises an annular connecting portion that extends axially along the central axis, The shank portion has an insertion portion that is inserted into the through hole, The outer circumferential surface of the insertion portion has a tapered shape, with the diameter decreasing as it is directed toward the other side in the axial direction. The inner circumferential surface of the aforementioned connecting portion has a tapered shape, with the diameter decreasing as it is directed toward the other side in the axial direction. In the axial direction, the diameter of the outer surface of the connecting portion is constant. The through hole has an insertion hole portion with a constant diameter, The outer circumferential surface of the connecting portion is in contact with the inner circumferential surface of the insertion hole portion. The hob cutter assembly according to any one of claims 3 to 6, wherein the outer circumferential surface of the insertion portion is in contact with the inner circumferential surface of the connection portion.

10. The first outer circumferential surface of the cylindrical portion, which includes the end on the other axial side of the cylindrical portion, has a tapered shape in which the diameter decreases as it is directed toward the other axial side. The hob cutter assembly according to claim 9, wherein the shape of the first outer surface and the shape of the outer surface of the insertion portion are the same.

11. The hob cutter assembly according to any one of claims 3 to 6, wherein the hob cutter is composed of a plurality of cutting edges that protrude radially outward from at least a portion of the outer circumferential surface of the cylindrical portion, and has a cutter portion that surrounds the cylindrical portion from the radially outward side.

12. The hob cutter assembly according to claim 11, wherein, viewed radially, a portion of the shank portion overlaps with at least a portion of the cutter portion.

13. A hob cutter assembly according to any one of claims 1 to 6, A drive unit that rotates the hob cutter assembly about the aforementioned central axis, A hobbing machine equipped with a hobbing machine.

14. A hob cutter in which a shank portion is detachably connected to one end on the axial side, A cylindrical portion extending axially along the central axis, The cutter portion is composed of a plurality of blades that protrude radially outward from at least a part of the outer circumferential surface of the cylindrical portion, and surrounds the cylindrical portion from the radially outward side, A hob cutter having [a certain feature].

15. The hob cutter according to claim 14, wherein the cylindrical portion has a through hole that penetrates the cylindrical portion in the axial direction.

16. The hob cutter according to claim 15, wherein the through hole has an insertion hole portion that is tapered in shape, with the diameter decreasing as it is directed toward the other side in the axial direction.

17. The hob cutter according to claim 14, which is made of cemented carbide or high-speed tool steel.

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