Patent ID: 7905018
Filing Date: 2011-03-15
Classification: B22F,F16H,Y10T

Abstract:
1. A production method for a sintered gear rotated around an axis, the sintered gear comprising: a tooth portion, an inner circumferential portion having a lower density than that of the tooth portion; and a step portion connecting the tooth portion and the inner circumferential portion, the method comprising: a step for compressing a sintered body in the axial direction, the sintered body comprising: wherein a thickness of the step forming portion gradually increases along the step excess wall portion from the inner circumference forming portion to the tooth forming portion in a cross section, wherein in the step for compressing the sintered body, the tooth excess wall portions of the tooth forming portion is crushed and the tooth portion is formed in a condition in which an outer circumferential surface of the sintered body is closely surrounded by a die, and at least the step excess wall portion of the step forming portion is compressed thereby crushing the step excess wall portion, flowing the material of the step forming portion toward the tooth forming portion, and forming the step portion between the tooth portion and the inner circumferential portion, and obtaining the sintered gear including the tooth portion, the inner circumferential portion projecting in the axial direction and disposed at a position biased from the tooth portion and the inner circumferential portion.