Manufacture of clutch components

Abstract

Clutch components for automotive use usually include a pair of clutch members with operative faces. In particular, planar one way clutches include a pair of clutch members whose operative faces are enclosed spaced opposition, with each clutch face including a plurality of recessed defining respective load bearing shoulders. A plurality of struts are disposed between the coupling face of the members, and such struts are moveable between the coupling position and non coupling position. A preferable method of manufacturing such clutch components includes powder metal operations comprising die compacting a metal powder into a metal blank, sintering the metal blank to form a sintered metal blank, and cooling the sintered metal blank to form a cooled metal blank. The preferred metallic structure of the cooled metal blank is 50-80% martensite and 20-50% bainite and fine pearlite. The application is especially useful for clutches used as backing plates in clutch brake applications.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to automotive clutch or transmission components and, more particularly, to so called one way clutches wherein one or more struts provide a mechanical coupling between opposed clutch faces and a pair of coaxially rotateable members.[0002]As explained in U.S. Pat. No. 6,571,926, in such one way clutches, a driving member engages a driven member.[0003]A thin flat strut is carried within each of the driving members' pockets such that a first longitudinal end may readily engage and bear against the shoulder defined by the corresponding recess in the driving member. The struts second, opposite longitudinal end is urged by spring force toward and against the driven member, thereby contacting a complimentary surface on the driven member.[0004]The materials and processing of such clutch components use high hardenability metals to produce the clutch components. Such materials can be used as backing plates in automotive transmissio...

AI Technical Summary

Benefits of technology

[0007]In a preferred method of manufacturing an automotive component in accordance with the present invention, a low alloy constituent, low hardenability material is utilized that accordingly requires a more aggressive cooling or quenching operation to produce a strong martensitic wear resistant hard structure. The preferred method includes the traditional powder metallurgy operation of die compacting and sintering that is followed by a quenching operation wherein the sintered material is quenched in an environment of a cooling rate that results in a metallic microstructure that is 50-80% martensitic, 20-50% bainitic with a small portion of fine pearlite, generally less than 10%. Quenching may include other quench methods than atmospheric. Because this material does not have high relative hardenability and transform as readily to martensite at a quench rate between 1.9° F. and 5.5° F. per second, untempered martensite is not formed by localized hot spots in the operation of the automotive component. Because there is almost no untempered martensite in the metallic microstructure, resulting from high localized temperatures fracture initiation sites are sufficiently reduced. The service life of the automotive transmission or clutch brake component such as a backing plate is greatly extended. Further, the resulting micro structure from reduction in hardenability reduces the material's propensity to crack propagation in the finished component.

Problems solved by technology

Further, the resulting micro structure from reduction in hardenability reduces the material's propensity to crack propagation in the finished component.

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