Sintered Bearing Manufacturing Using Diffusion Alloyed Iron-Copper Powder
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Solution Overview
Problem
Sintered bearings used in vibration motors experience increased rotation fluctuation and wear due to low neck strength between iron and copper phases, leading to early bearing surface wear and high costs associated with using expensive metals like Ni and Mo.
Innovation Solution
A method for manufacturing sintered bearings by diffusing copper powder into iron powder, using a low-melting-point metal powder for secure bonding through liquid phase sintering, achieving high neck strength and wear resistance without expensive metals, and optimizing sintering conditions to form a two-phase iron structure with ferrite and pearlite phases for improved radial crushing strength and initial conformability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copper-coated iron powder is compacted and sintered to form a sintered bearing, then the bearing can be manufactured with iron and copper phases, but the neck strength between the iron phase and copper phase is low leading to early bearing surface wear
Solution Approach 1:
A low-melting-point metal powder is introduced as an intermediary substance between the iron powder and copper powder. During sintering, this low-melting-point metal melts and forms a bonding bridge between the iron and copper phases, significantly enhancing the neck strength at the phase interfaces and preventing early bearing surface wear.
Solution Approach 2:
The sintering temperature is controlled to be above the melting point of the low-melting-point metal but below the melting points of iron and copper. This parameter change enables the low-melting-point metal to melt and facilitate bonding while keeping the iron and copper phases solid, creating strong interfacial bonds between phases.
2Reliability
If mixed powder containing Ni, Mo, and other metal powders is compacted and sintered to improve bearing surface wear resistance, then the wear resistance improves, but the manufacturing cost increases due to expensive metal powders
Solution Approach 1:
Instead of using expensive metal powders like Ni and Mo, a low-melting-point metal powder with lower cost is used. This cheaper material achieves the same wear resistance improvement by forming strong bonds at phase interfaces through melting during sintering, significantly reducing manufacturing costs while maintaining reliability.
3Strength
If sintering temperature is increased to strengthen the sintered bearing, then the radial crushing strength improves, but the bearing surface conformability and oil retention deteriorate
Solution Approach 1:
The sintering temperature is precisely controlled within a specific range above the melting point of the low-melting-point metal but below the melting points of iron and copper. This optimized temperature parameter enables strong phase bonding through low-melting-point metal melting while preserving the porous structure and surface conformability needed for oil retention and bearing performance.
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 produces sintered bearings with enhanced wear resistance and radial crushing strength, reducing rotation fluctuation and enabling stable high-rotation performance in vibration motors at a lower cost, without the need for expensive metals or additional shape correction processes.
Implementation Method 1
diffusion alloyed powder in which a copper powder is partly diffused in an iron powder
Implementation Method 2
the low-melting-point metal powder contained in the green compact melts as the green compact is sintered in the sintering step
Implementation Method 3
it is possible to achieve secure bonding between an iron structure and a copper structure or between copper structures of neighboring diffusion alloyed powder grains by liquid phase sintering
Implementation Method 4
the neck strength between the iron structure and the copper structure is further increased because the melted low-melting-point metal diffuses therein
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The present invention relates to a method for manufacturing a sintered bearing having a bearing surface that forms a bearing gap with a shaft to be supported, in its inner periphery. This manufacturingmethod includes : a compacting step P2 of compacting a base powder containing a diffusion alloyed powder 11 prepared by partially diffusing a copper powder in an iron powder as a main material, a low-melting-point metal powder 14, and a solid lubricant to obtain a green compact, and a sintering step P3 of sintering the green compact 4' to obtain a sintered compact 4".