Holder for gear machining

Abstract

The present invention provides a gear cutting holder that can withstand the machining load acting on the workpiece, suppress the movement of the workpiece, and enable high-precision machining in the gear cutting process of spiral bevel gears or hypoid gears. [Solution] The holder 60 has a male spline 62 that engages with the female spline 50 of the workpiece 42 when holding the workpiece 42. As a result, in the gear cutting process of the bevel gear 40, the machining load F acting on the workpiece 42 is absorbed by the spline engagement between the female spline 50 of the workpiece 42 and the male spline 62 of the holder 60. Therefore, it is possible to provide a gear machining holder 60 that suppresses the movement of the workpiece 42 and enables high-precision machining.

Description

Technical Field

[0001] The present invention relates to a holder for gear machining that holds a workpiece during the tooth cutting of a spiral bevel gear or a hypoid gear.

Background Art

[0002] Tooth cutting of a spiral bevel gear or a hypoid gear is known to be performed by rotating a tool having a cutting blade, for example, called a tooth cutting cutter, with respect to a workpiece to be machined at a position that matches the tooth twist angle. For example, the method for manufacturing a spiral bevel gear (spiral bevel gear) or a hypoid gear described in Patent Document 1 is like this.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the tooth cutting process, due to the cutting by the rotation of the tooth cutting cutter, the workpiece receives a machining load, which is a large load in the tooth twist angle direction (circumferential direction and outer diameter direction). In order to prevent the workpiece from moving due to this machining load, a holder for gear machining that holds the workpiece is required, and conventionally, an expander or the like has been used. An expander is a mechanism that arranges a disc spring in the inner diameter portion of the workpiece and applies a load (holding force) by expanding the outer diameter of the disc spring by tightening a bolt, and the workpiece is prevented from moving even when receiving the machining load by this holding force.

[0005] Incidentally, while holding with an expander is effective for workpieces (gears) with a large inner diameter, the holding force is weak for workpieces (gears) with a small inner diameter. Furthermore, if the inner diameter of the workpiece is splined, the holding force is even weaker, leading to the problem of the workpiece moving due to the machining load during gear cutting.

[0006] The present invention was made against the above circumstances, and its objective is to provide a gear cutting holder that can withstand the machining load acting on the workpiece, suppress the movement of the workpiece, and enable high-precision machining in the gear cutting process of spiral bevel gears or hypoid gears. [Means for solving the problem]

[0007] The gist of the present invention is (a) a gear cutting holder for holding a workpiece having a first spline on the back side relative to the tooth surface in the direction of the rotation axis during gear cutting of a spiral bevel gear or hypoid gear, and (b) the holder has a second spline that engages with the first spline when holding the workpiece. [Effects of the Invention]

[0008] According to the present invention, the holder has a second spline that engages with the first spline when holding the workpiece. As a result, in the gear cutting process of a spiral bevel gear or hypoid gear, the machining load acting on the workpiece is absorbed by the engagement of the first spline of the workpiece with the second spline of the holder, thereby suppressing the movement of the workpiece and enabling high-precision machining. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating the general method for cutting the teeth of a spiral bevel gear or hypoid gear. [Figure 2] This is a schematic diagram illustrating a conventional example of a retainer used in gear cutting. [Figure 3] This is a schematic diagram illustrating the configuration of a holder to which the present invention is applied in gear cutting. [Modes for carrying out the invention]

[0010] An embodiment of the present invention will be described in detail below with reference to the drawings. In the following embodiment, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily accurately depicted. Also, in the embodiment, a spiral bevel gear or a hypoid gear will be referred to as a "spiral bevel gear," including hypoid gears. [Examples]

[0011] Figure 1 is a schematic diagram illustrating the general method of cutting the teeth of a spiral bevel gear 10. Here, the object to be machined for the spiral bevel gear 10 is the workpiece 12. Figure 1 is a view of the spiral bevel gear 10 (workpiece 12) from the tooth surface 14 side. The axis CA indicates the rotational center line of the spiral bevel gear 10 (workpiece 12).

[0012] The gear cutting of the spiral bevel gear 10, that is, the gear cutting of the workpiece 12, is performed using a gear cutting cutter 20. The gear cutting cutter 20 is equipped with multiple cutting blades 22, each consisting of an inner blade 22a and an outer blade 22b, and the cutting blades 22 are arranged on a circumference centered on the axis CT of the gear cutting cutter 20. In the cutting blades 22, the inner blade 22a has a cutting edge radially inward from the axis CT, and the outer blade 22b has a cutting edge radially outward. As shown in Figure 1, by rotating the cutting blades 22 clockwise around the axis CT, the tooth surface 14 of the workpiece 12 is cut by the inner blades 22a and the outer blades 22b, forming a tooth groove 16. The axis CT, the inner blades 22a and the outer blades 22b are arranged so that the tooth groove 16 is formed at a set helix angle. The tooth groove 16 is formed repeatedly around the entire circumference of the tooth surface 14 of the workpiece 12, thereby performing the tooth cutting process for the bevel gear 10.

[0013] During gear cutting, the workpiece 12 is subjected to a large machining load F in the helix direction, i.e., in the circumferential and radial directions of the workpiece 12, due to the cutting caused by the rotation of the cutting blade 22. In Figure 1, the machining load F is indicated by a black arrow. In gear cutting, a gear cutting holder is required to hold the workpiece so that it does not move due to this machining load F, and conventionally, an expander 30 or the like has been used.

[0014] Figure 2 is a schematic diagram illustrating an expander 30, a conventional example of a holder used in gear cutting, and shows a cross-sectional view at the axis CA during gear cutting on the workpiece 12.

[0015] The expander 30 comprises a base portion 32, an upper portion 34, and a disc spring 36. The disc spring 36 is a disc-shaped spring centered on an axis CA and connected to both the base portion 32 and the upper portion 34. The outer diameter of the disc spring 36 is adjusted by adjusting the gap between the base portion 32 and the upper portion 34 using a bolt 38.

[0016] During gear cutting, the workpiece 12 is placed on the base portion 32 with the tooth surface 14 facing upward in the plane of the paper, and the disc spring 36 is housed inside the inner diameter portion 18. When the bolt 38 is tightened, the gap between the base portion 32 and the upper portion 34 in the axial direction CA is narrowed, and consequently the outer diameter of the disc spring 36 expands. As a result, the disc spring 36 comes into contact with the inner diameter portion 18 of the workpiece 12, and a load (holding force) is applied to the inner diameter portion 18. The expander 30 holds the workpiece 12 in place by this holding force, preventing it from moving even when subjected to a machining load F.

[0017] Incidentally, while holding with the expander 30 is effective for workpieces (gears) with a large inner diameter, the holding force becomes weaker for workpieces (gears) with a small inner diameter. Furthermore, if the inner diameter of the workpiece is splined, the holding force becomes even weaker, resulting in the problem that the workpiece moves under the machining load F during gear cutting.

[0018] FIG. 3 is a schematic diagram for explaining the configuration of the fixture 60 to which the present invention is applied in gear cutting. The fixture 60 holds the workpiece 42 to be machined of the helical spur gear 40, and gear cutting is performed. FIG. 3(a) is a cross-sectional view taken along the axial center CB which is the rotation center line of the workpiece 42, and FIG. 3(b) is a view seen from the lower side of the paper surface of FIG. 3(a), that is, a view seen from the back side with respect to the tooth surface 44 of the workpiece 42. Further, FIG. 3(c) is a view obtained by adding the holding state by the fixture 60 to FIG. 3(a).

[0019] On the flange portion 46 on the back side with respect to the tooth surface 44 of the workpiece 42, a convex portion 48 is provided, and an internal female spline 50 is provided in the rotational axis direction of the workpiece 42 on the inner diameter side of the convex portion 48, that is, in the axial center CB direction. The internal female spline 50 corresponds to the "first spline" of the present invention.

[0020] As shown in FIG. 3(c), when holding the workpiece 42, the fixture 60 holds the workpiece 42 by fitting the inner diameter portion 52 from below the paper surface in the axial center CB direction and supporting the convex portion 48. Further, the fixture 60 includes a male spline 62 that fits into the internal female spline 50 of the workpiece 42. By fitting the internal female spline 50 of the workpiece 42 and the male spline � of the fixture 60, the machining load F acting on the workpiece 42 during gear cutting is received, and the movement of the workpiece 42 is suppressed. The male spline 62 corresponds to the "second spline" of the present invention.

[0021] The positions, shapes, dimensions, etc. of the convex portion 48, internal female spline 50 of the workpiece 42, the fixture 60, male spline 62, etc. are set to suitable values determined in advance by design or experiment so that the machining load F during gear cutting is received by spline fitting and the movement of the workpiece 42 is suppressed.

[0022] As described above, according to the present embodiment, when the holder 60 holds the workpiece 42, it has a male spline 62 that fits with the female spline 50 of the workpiece 42. Thereby, in the gear cutting process of the skew bevel gear 40, the machining load F acting on the workpiece 42 is received by the spline fitting between the female spline 50 of the workpiece 42 and the male spline 62 of the holder 60, so the movement of the workpiece 42 is suppressed and machining is performed with high accuracy.

[0023] As described above, the embodiments of the present invention have been described in detail based on the drawings, but the present invention is also applicable in other aspects.

[0024] For example, in the above-described embodiment, it was the spline fitting between the female spline 50 of the workpiece 42 and the male spline 62 of the holder 60. However, instead of the female spline 50 of the workpiece 42, a male spline may be formed in the axial center CB direction on the outer diameter side of the convex portion 48, and a female spline that fits with this may be formed on the holder 60.

[0025] Note that what has been described above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art without departing from the spirit thereof.

Explanation of Reference Numerals

[0026] 10, 40: Skew bevel gear (skew bevel gear or hypoid gear) 12, 42: Workpiece 14, 44: Tooth surface 50: Female spline (first spline) 60: Holder 62: Male spline (second spline)

Claims

[Claim 1] A gear machining holder for holding a workpiece having a first spline on the back side relative to the tooth surface in the direction of the rotation axis, during gear cutting of a bevel gear or hypoid gear, The holder has a second spline that engages with the first spline when holding the workpiece. A holder for gear machining characterized by the following features.

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