CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2019/002555 filed Jan. 25, 2019, claiming priority based on Japanese Patent Application No. 2018-015722 filed Jan. 31, 2018 the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure is related to: a manufacturing method of a tooth part including a tubular portion, an inner tooth portion formed on an inner peripheral surface of the tubular portion, and an outer tooth portion formed on an outer peripheral surface of the tubular portion; a tooth part; and a processing device of a tooth part.

BACKGROUND ART

Conventionally, as a tooth part, a multi-plate clutch outer drum formed by press working a steel plate is known (for example, see Patent Document 1). The multi-plate clutch outer drum includes an end wall portion, a cylindrical portion (tubular portion) in which one end is connected to an outer peripheral end of the end wall portion and the other end is open, a large number of spline grooves and spline protrusions (inner tooth portions) that are arranged alternately in the circumferential direction on an inner peripheral surface of the cylindrical portion so as to extend in an axial direction, and an outer protrusion and an outer groove (outer tooth portion) formed on an outer peripheral surface of the cylindrical portion so as to correspond to each spline groove and spline protrusion. Conventionally, as a tooth part formed by press working, a cup shaped part including the following (for example, see Patent Document 2) is known: a disc-shaped bottom portion; a cylindrical portion (tubular portion) standing on an outer periphery of the bottom portion; and an inner peripheral recessed/protruded portion (inner tooth portion) including a plurality of protruded portions formed on an inner peripheral surface of the cylindrical portion and a plurality of recessed portions formed on an inner peripheral surface of the cylindrical portion so as to each be extended in an axial direction of the cylindrical portion. In the cup-shaped part, a plurality of outer peripheral recessed portions are formed on a bottom (base end) side of the outer peripheral surface of the cylindrical portion. Here, in the outer peripheral recessed portion, the outer peripheral surface is recessed radially inward at a position corresponding to the inner peripheral protruded portion. Further, on the open end side of the outer peripheral surface of the cylindrical portion, a smooth outer peripheral portion having generally the same diameter over the entire circumference of the outer peripheral surface is formed.

RELATED ART DOCUMENTS

Patent Documents

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-57687 (JP 2006-57687 A)

Patent Document 2: Japanese Unexamined Patent Application Publication No. 2013-53643 (JP 2013-53643 A)

SUMMARY OF THE DISCLOSURE

Problem to be Solved by Various Aspects of the Disclosure

In the cup-shaped part described in Patent Document 2, since the smooth outer peripheral portion having no thickness reduction is formed on the open end portion side of the outer peripheral surface of the cylindrical portion, it is possible to further improve the strength of the cylindrical portion on the open end portion side, compared to the multi-plate clutch outer drum according to Patent Document 1. However, in the cup-shaped part described in Patent Document 2, the thickness of the open end portion of the cylindrical portion is increased due to the smooth outer peripheral portion being formed. Thus, when the open end portion is cut to adjust the axial length of the cylindrical portion, chipping of the cutting tool etc. may occur due to impact and friction of intermittent cutting. Further, when cutting the open end portion including the smooth outer peripheral portion by plastic working in order to adjust the axial length of the cylindrical portion, a large load needs to be applied to cut the open end portion.

Means for Solving the Problem

An aspect of the disclosure is to allow an axial length of a tubular portion to be easily adjusted while satisfactorily ensuring rigidity of a tooth part including a tubular portion, an inner tooth portion formed on an inner peripheral surface of the tubular portion, and an outer tooth portion formed on an outer peripheral surface of the tubular portion.

A manufacturing method of a tooth part of the present disclosure is a manufacturing method of a tooth part including a tubular portion, an inner tooth portion formed on an inner peripheral surface of the tubular portion, and an outer tooth portion formed on an outer peripheral surface of the tubular portion. In the manufacturing method, a plurality of inner peripheral wall portions that each extend in an axial direction of the tubular portion and form a tooth tip portion of the inner tooth portion and a tooth bottom portion of the outer tooth portion, a plurality of outer peripheral wall portions that each extend in the axial direction and form a tooth bottom portion of the inner tooth portion and a tooth tip portion of the outer tooth portion, and a plurality of tooth surface portions that each extend in the axial direction and connect the corresponding inner peripheral wall portion and the corresponding outer peripheral wall portion are formed in the tubular portion. Also in the manufacturing method, an annular rib that extends in an annular shape on a radially outer side than the inner peripheral wall portions is formed by pushing out the inner peripheral wall portions and the tooth surface portions radially outward while shearing, at an open end of the tubular portion.

Such a method forms the annular rib that extends in an annular shape on a radially outer side than the inner peripheral wall portions by pushing out the inner peripheral wall portions and the tooth surface portions radially outward while shearing, at the open end of the tubular portion. By forming the annular rib at the open end of the tubular portion in this way, the rigidity of the tooth part can be increased. Further, the thickness of the annular rib is substantially the same as the thickness of the inner peripheral wall portion and the tooth surface portion. Thus, since the annular rib can be easily cut, the axial length of the tubular portion of the tooth part can be easily adjusted. As a result, the axial length of the tubular portion can be easily adjusted while the rigidity of the tooth part is satisfactorily ensured.

