Sintered Bearing With Concentration Gradient Inner Outer Layers
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Solution Overview
Problem
Sintered bearings used in construction machinery face challenges in achieving high wear resistance and cost-effectiveness, as the addition of hardness-increasing elements like Ni, Mo, and Cr increases production costs and complicates dimension accuracy due to increased hardness of the outer peripheral surface.
Innovation Solution
A sintered bearing design featuring an inner layer with a hardness-increasing element and an outer layer without, integrated through a concentration gradient at their interface, allowing for enhanced hardness on the bearing surface while maintaining lower material costs and improved processability for accurate dimensioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire sintered bearing is made of sintered metal containing hardness increasing elements (Ni, Mo, Mn, Cr) to increase bearing surface hardness, then wear resistance is improved, but production cost increases and processability of the outer peripheral surface deteriorates
Solution Approach 1:
The patent applies local quality by creating a layered structure where the inner layer contains hardness increasing elements (Ni, Mo, Mn, or Cr) to provide wear resistance at the bearing surface, while the outer layer excludes these elements to maintain low cost and good processability for mounting operations. This spatial differentiation of material properties resolves the contradiction between needing high hardness for wear resistance and maintaining ease of manufacture for the outer peripheral surface.
2Reliability
If the entire sintered bearing is made of sintered metal containing hardness increasing elements to increase bearing surface hardness, then wear resistance is improved, but material cost increases
Solution Approach 1:
The invention uses local quality by restricting expensive hardness increasing elements to only the inner layer where the bearing surface is located, while the outer layer uses conventional sintered metal without these elements. This localized application of costly materials achieves the required wear resistance at the critical bearing surface while significantly reducing overall material cost compared to using hardness increasing elements throughout the entire bearing.
3Reliability
If hardness of the bearing surface is increased to be equal to or higher than hardness of the shaft to reduce replacement frequency, then wear resistance is improved, but the outer peripheral surface becomes too hard for accurate dimensional finishing
Solution Approach 1:
The patent implements local quality by differentiating material composition between the inner and outer layers. The inner layer contains hardness increasing elements to achieve high bearing surface hardness for extended wear life, while the outer layer excludes these elements to maintain lower hardness that enables accurate dimensional finishing of the mounting surface. This spatial separation of material properties simultaneously achieves both high reliability and high manufacturing precision.
Data Source
AI summary
Provided is a sintered bearing (1) including an inner layer (2) and an outer layer (3) formed by integral molding, the sintered bearing (1) having a bearing surface (A) formed on an inner peripheral surface (2a) of an inner layer (2). The inner layer (2) is made of sintered metal containing Fe and a hardness increasing element (such as Ni or Mo). The outer layer (3) is made of sintered metal containing Fe and no hardness increasing element. A concentration gradient of the hardness increasing element is present at an interface between the inner layer (2) and the outer layer (3).