Sintered Metal Connecting Rod Density Control Against Warpage
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Solution Overview
Problem
Sintered metal connecting rods experience shape accuracy issues due to warpage caused by sintering, leading to parallelism problems between the large and small end portions, which can result in premature abrasion and abnormal noise in engine components.
Innovation Solution
A sintered metal connecting rod with controlled density differences between the large end, small end, and stem portions, achieved through specific compression molding techniques using a divided molding die, which reduces warpage and ensures parallelism between through-holes to ϕ0.5/100 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sintering is used to manufacture the connecting rod, then manufacturing cost is reduced, but shape accuracy deteriorates due to warpage
Solution Approach 1:
The invention applies preliminary action by controlling the density distribution in the green compact before sintering. By adjusting the compression molding parameters to create specific density variations in different regions (higher density in the stem portion, lower density in the large and small end portions), the warpage that occurs during sintering is pre-compensated for, resulting in a final product with improved shape accuracy and through-hole parallelism
2Productivity
If compression molding is applied to form the green compact, then manufacturing efficiency is improved, but warpage increases during subsequent sintering
Solution Approach 1:
The invention applies local quality by creating non-uniform density distribution within the green compact. Different regions are compressed to different densities: the stem portion is compressed to higher density while the large and small end portions are compressed to lower density. This localized density control compensates for the warpage that occurs during sintering, maintaining shape accuracy while preserving the manufacturing efficiency of compression molding
3Reliability
If the through-holes in the large and small end portions are not parallel, then bearing wear increases and abnormal noise occurs
Solution Approach 1:
The invention applies preliminary action by pre-controlling the density distribution in the green compact to compensate for warpage during sintering. This ensures that the through-holes in the large and small end portions remain parallel after sintering, preventing one-sided bearing contact and abnormal noise, thereby improving bearing durability and engine reliability
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 solution effectively suppresses warpage and parallelism errors, preventing premature abrasion and abnormal noise while maintaining cost-effectiveness and ensuring accurate assembly of engine components.
Implementation Method 1
a compression molding step of subjecting metal powder to compression molding to obtain a green compact
Implementation Method 2
a sintering step of sintering the green compact to obtain a sintered compact
Data Source
AI summary
A sintered metal connecting rod (10) includes as an integrated body, a large end portion (11), a small end portion (12), and a stem portion (13). In the sintered metal connecting rod (10), division marks (14a, 14b) of a molding die by a compression molding are formed between the large end portion (11) and the stem portion (13) and between the small end portion (12) and the stem portion (13) on one of front and back surface (11c to 13c) in which the through-holes (11a, 12a) are formed, respectively. The large end portion (11) and the stem portion (13) have a density difference of 4% or less, and the small end portion (12) and the stem portion (13) have a density difference of 4% or less.