Sintered Bearing Ring Raceway for Low-Cost Fatigue Life
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Solution Overview
Problem
The existing methods for manufacturing raceway rings for rolling bearings face challenges in reducing manufacturing costs and ensuring sufficient rolling fatigue life due to the high cost of specialized steel powders and the risk of coarse pores forming near the raceway surface, which can lead to peeling and reduced fatigue life.
Innovation Solution
A raceway ring formed by subjecting Fe-Ni-Mo based partially diffusion-alloyed steel powder to compression molding and sintering, where the powder consists of 0.5 wt% to 5 wt% Ni and 0.5 wt% to 3 wt% Mo, with a maximum pore envelope area estimated to be less than 50 µm, preventing coarse pores and enhancing densification through plastic working.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas-atomized completely alloyed steel powder is used for sintering, then high density and fine pore structure are achieved, but manufacturing cost increases significantly
Solution Approach 1:
The invention changes the chemical composition parameters of the steel powder from conventional high-alloy compositions (containing Cr, Mn, Mo, V, Ti) to a low-alloy composition (C: 0.95-1.30 wt%, Si: 0.05-0.40 wt%, Mn: 0.05-0.30 wt%, with remaining Fe). This parameter change enables achieving the required pore structure and mechanical properties at lower cost while maintaining high density and fine pore control through the optimized composition
Solution Approach 2:
The invention replaces expensive specialized steel powders with cheaper, more commonly available steel powder compositions. By using a simplified alloy system with lower content of expensive alloying elements, the invention achieves comparable or superior pore structure control and mechanical properties without the high material costs associated with gas-atomized completely alloyed powders
2Strength
If Fe-Cr-Mo based alloyed powder is used, then high strength is achieved, but coarse pores form near the raceway surface reducing fatigue life
Solution Approach 1:
The invention changes the alloy composition parameters by eliminating Cr and reducing Mo content, instead optimizing C, Si, and Mn content. This parameter change prevents coarse pore formation near the raceway surface while maintaining high mechanical strength and improving rolling fatigue life through controlled densification and fine pore structure
Solution Approach 2:
The invention applies local quality control by optimizing the pore structure specifically in the region near the raceway surface. Through the optimized low-alloy composition and sintering process, the invention achieves fine pore distribution and high density in the critical surface region, preventing coarse pores that would reduce fatigue life, while maintaining overall high strength
3Manufacturing precision
If machine processing is used to obtain intermediate processed product, then high accuracy is achieved, but material loss increases and manufacturing efficiency decreases
Solution Approach 1:
The invention performs preliminary action by optimizing the powder composition and sintering process to achieve near-net-shape forming directly during sintering. This preliminary optimization of material properties and process parameters eliminates the need for subsequent extensive machine processing, thereby reducing material loss and improving manufacturing efficiency while maintaining high accuracy
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
This approach reduces manufacturing costs and achieves a rolling fatigue life comparable to ingot materials by preventing coarse pore formation and ensuring high density, thus enhancing the durability of the raceway ring.
Implementation Method 1
subjecting Fe-Ni-Mo based partially diffusion-alloyed steel powder to compression molding
Implementation Method 2
followed by sintering
Implementation Method 3
the partially diffusion-alloyed steel powder is powder in which Ni is diffused on and joined to a periphery of Fe-Mo alloy
Implementation Method 4
the raceway surface being formed by subjecting a sintered metal material to plastic working
Data Source
Figure 1a~2
Figure 3~4b
Figure 5~6
AI summary
Partially diffusion-alloyed steel powder is subjected to compression molding and then sintered to form a sintered metal material (10'), and a raceway surface (2) is formed on the sintered metal material (10') through plastic working, to thereby manufacture a raceway ring (1). With at least a risk volume of the raceway ring (1) being adopted as a prediction volume, a square root √areamax of the maximum pore envelope area estimated to be present at least in the prediction volume is set to be less than 50 µm. With this, there is provided a raceway ring for a rolling bearing that has an increased rolling fatigue life at low cost.