Powder Metal Internal Ring Structure for High-Strength Torque Parts
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Solution Overview
Problem
Powder metal parts containing copper face challenges in maintaining size and uniformity due to expansion during sintering, particularly in larger components, leading to tolerance issues and reduced durability.
Innovation Solution
A method involving a toroidal part structure with an external forged or wrought metal layer and an internal sintered powder metal layer that expands more during sintering, creating compressive forces for enhanced strength and durability, utilizing a powder metal composition with at least 1% copper to achieve high strength and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If copper is added to the metal powder to promote rapid hardening, then hardening speed is improved, but dimensional tolerance deteriorates due to expansion during sintering
Solution Approach 1:
The part is divided into two distinct layers: an outer layer made from low-copper powder metal and an inner layer made from high-copper powder metal. This segmentation allows each layer to have optimized properties - the outer layer provides dimensional stability while the inner layer provides rapid hardening, resolving the contradiction between hardening speed and dimensional tolerance.
Solution Approach 2:
Different regions of the part have different copper concentrations tailored to their specific functional requirements. The outer surface region has low copper content for dimensional precision, while the inner region has high copper content for rapid hardening. This local quality differentiation resolves the contradiction by applying the appropriate material composition to each region.
2Strength
If copper content is increased to improve hardening, then hardening performance is improved, but part uniformity deteriorates due to variable expansion
Solution Approach 1:
The uniformity problem is resolved by segmenting the part into layers with controlled copper content. The outer layer uses low-copper powder for uniform dimensional stability, while the inner layer uses high-copper powder for uniform rapid hardening. Each layer's uniform composition eliminates the variability problem while achieving the desired hardening performance.
Solution Approach 2:
The copper concentration parameter is changed across different layers of the part. By controlling the copper content to be low in the outer layer and high in the inner layer, the invention achieves both uniform dimensional stability in the outer region and uniform rapid hardening in the inner region, resolving the contradiction between hardening performance and part uniformity.
3Temperature
If copper is added to achieve rapid hardening, then hardening speed is improved, but part strength deteriorates due to tolerance variations
Solution Approach 1:
The part is segmented into outer and inner layers with different copper contents. The outer layer's low copper content ensures dimensional tolerance and structural strength, while the inner layer's high copper content provides rapid hardening. This segmentation resolves the contradiction by isolating the rapid hardening function to the inner layer while preserving overall part strength through the outer layer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in parts with superior strength and durability, capable of meeting stringent performance requirements without compromising tolerances or uniformity, with the internal sintered layer becoming extremely strong and hard due to compressive forces and metal bonding.
Implementation Method 1
the internal component is comprised of a powder metal which expands to a greater degree than does the forged power metal or the wrought metal during sintering
Implementation Method 2
The green metal part is then sintered at an elevated temperature to produce the powder metal part
Data Source
AI summary
By utilizing the technique of this invention, parts such as gears, bearing races, and one-way clutches, which could previously only be made via labor intensive machining procedures can be made utilizing power metal technology. The subject invention provides a method of manufacturing a high strength part which comprised (1) providing an external component having an external profile and an internal profile, wherein the external component is comprised of a forged powder metal or a wrought metal; (2) compacting a powder metal composition within the internal profile of the external component to produce a green internal component having a desired internal profile; and (3) sintering the green internal component within the confines of the external component to produce high strength part, and wherein the internal component is comprised of a powder metal which expands to a greater degree than does the forged power metal or the wrought metal during sintering.