Power transmission shaft and spline-processing method

Patent metadata

Field	Value
Publication number	US-2016298693-A1
Application number	US-201414777881-A
Country	US
Kind code	A1
Filing date	Mar 12, 2014
Priority date	Mar 25, 2013
Publication date	Oct 13, 2016
Grant date	—

Abstract

A power transmission shaft including a male spline formed in an outer periphery thereof, and a diameter increasing portion formed on a part of a tooth bottom of the male spline, which is located on an opposite side to an axial end of the power transmission shaft. The tooth bottom of the male spline has a substantially constant circumferential width extending up to an axial region of the diameter increasing portion. The diameter increasing portion includes a chamfered portion formed in the axial region of the diameter increasing portion, the chamfered portion connecting the tooth bottom and a tooth flank of the male spline to each other to reduce a tooth groove width.

First claim

1 . A power transmission shaft, comprising:
a male spline formed in an outer periphery thereof; and a diameter increasing portion formed on a part of a tooth bottom of the male spline, which is located on an opposite side to an axial end of the power transmission shaft, by gradually increasing an outer diameter dimension of the tooth bottom, the tooth bottom of the male spline having a substantially constant circumferential width extending up to an axial region of the diameter increasing portion, the diameter increasing portion comprising a chamfered portion formed in the axial region of the diameter increasing portion, the chamfered portion connecting the tooth bottom and a tooth flank of the male spline to each other to reduce a tooth groove width, the tooth bottom, the tooth flank, and the chamfered portion each comprising a press-formed surface, and the power transmission shaft satisfying a relationship of C>D, where C represents an axial dimension between a diameter increase start position (P 1 ) and a tooth groove width reduction start position (P 2 ) of the male spline, and D represents an axial dimension between the tooth groove width reduction start position (P 2 ) and a diameter increase finish position (P 3 ) of the male spline.

2 . The power transmission shaft according to claim 1 , wherein the male spline has a tooth tip comprising a surface free from being subjected to press forming using a die.

3 . The power transmission shaft according to claim 1 , wherein the power transmission shaft has an angle ( 01 ) of from 25° to 40°, which is formed by a straight line (K) connecting the diameter increase start position (P 1 ) and the tooth groove width reduction start position (P 2 ) of the male spline to each other, and by an axial outline of the tooth bottom of the male spline.

4 . The power transmission shaft according to claim 1 , wherein the chamfered portion comprises a flat surface.

5 . The power transmission shaft according to claim 1 , wherein the chamfered portion comprises a curved recessed surface.

6 . The power transmission shaft according to claim 1 , wherein a corner portion connecting the chamfered portion and the tooth bottom to each other or a corner portion connecting the chamfered portion and the tooth flank to each other is rounded off.

7 . The power transmission shaft according to claim 1 , wherein the power transmission shaft comprises a hollow shaft to be connected to a constant velocity universal joint.

8 . A spline-processing method for a power transmission shaft,
the power transmission shaft comprising:
a male spline formed in an outer periphery thereof; and
a diameter increasing portion formed on a part of a tooth bottom of the male spline, which is located on an opposite side to an axial end of the power transmission shaft, by gradually increasing an outer diameter dimension of the tooth bottom,
the spline-processing method comprising forming the male spline by press working using a die, the die comprising:
a tooth bottom forming surface for forming the tooth bottom of the male spline;
a tooth flank forming surface for forming a tooth flank,
the tooth bottom forming surface having a substantially constant circumferential width extending up to an axial region of the diameter increasing portion; and
a chamfered portion forming surface for forming a chamfered portion in the axial region of the diameter increasing portion, the chamfered portion forming surface connecting the tooth bottom forming surface and the tooth flank forming surface to each other to reduce a tooth groove width,
the press working being performed using the die so that a relationship of C>D is satisfied, where C represents an axial dimension between a diameter increase start position (P 1 ) and a tooth groove width reduction start position (P 2 ) of the male spline, and D represents an axial dimension between the tooth groove width reduction start position (P 2 ) and a diameter increase finish position (P 3 ) of the male spline.

9 . The spline-processing method for a power transmission shaft according to claim 8 , wherein the die is set to have an inner-diameter surface larger than a large diameter of the male spline.

10 . The power transmission shaft according to claim 2 , wherein the power transmission shaft has an angle ( 01 ) of from 25° to 40°, which is formed by a straight line (K) connecting the diameter increase start position (P 1 ) and the tooth groove width reduction start position (P 2 ) of the male spline to each other, and by an axial outline of the tooth bottom of the male spline.

11 . The power transmission shaft according to claim 2 , wherein the chamfered portion comprises a flat surface.

12 . The power transmission shaft according to claim 2 , wherein the chamfered portion comprises a curved recessed surface.

13 . The power transmission shaft according to claim 2 , wherein a corner portion connecting the chamfered portion and the tooth bottom to each other or a corner portion connecting the chamfered portion and the tooth flank to each other is rounded off.

14 . The power transmission shaft according to claim 2 , wherein the power transmission shaft comprises a hollow shaft to be connected to a constant velocity universal joint.

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• Hiraoka Tsuneaki
• Asano Yuichi
• Kitamura Yuichiro
• Suzuki Kiyohiro

Classifications

• F16D2003/22313

  Details of the inner part of the core or means for attachment of the core on the shaft · CPC title

• F16D1/072

  involving plastic deformation (plastic welding F16D1/068) · CPC title

• F16D3/2245

  where the groove centres are offset from the joint centre · CPC title

• B21K1/066

  splined · CPC title

• F16D2001/103

  the torque is transmitted via splined connections · CPC title