Ironing Mold Shoulder Radius for Precision Forming Without Powdery Residue
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Solution Overview
Problem
The existing ironing processes for folded and drawn formed portions often result in excessive load on the surface treated layer, leading to powdery residue generation and dimensional precision issues due to residual compressive stress and uneven material thickness.
Innovation Solution
An ironing mold with a die having a shoulder portion with a specific curvature radius and skewness, along with a counter pad, is designed to minimize the load on the surface treated layer by controlling the clearance between the punch and die, ensuring the curvature radius and skewness parameters satisfy certain conditions to prevent excessive material crushing and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the folded and drawn formed portion is ironed by pushing it into the pushing hole, then the material is thinned and dimensional precision is improved, but the surface treated layer is shaved and powdery residue is generated
Solution Approach 1:
The invention changes the geometric parameters of the die, specifically setting the curvature radius of the shoulder portion to satisfy 0.5mm < r ≤ 2.0mm and the skewness to satisfy -0.6 ≤ Rsk < 0. These parameter changes optimize the ironing process to reduce surface layer damage while maintaining dimensional precision
Solution Approach 2:
The die shoulder portion is designed with a specific curvature radius (0.5mm < r ≤ 2.0mm) to create a smooth transition zone during ironing. This curvature prevents sharp edges from shaving the surface treated layer, thereby reducing powdery residue generation while still achieving the desired thinning and dimensional precision
2Productivity
If the radius of the shoulder portion is small, then the ironing process is more efficient, but the material is crushed and large residual compressive stress is generated
Solution Approach 1:
The invention optimizes the curvature radius parameter to a specific range (0.5mm < r ≤ 2.0mm) that balances ironing efficiency with stress control. This parameter setting allows effective material thinning while preventing excessive crushing and residual stress accumulation
Solution Approach 2:
The curved shoulder portion with optimized radius provides a gradual deformation zone that distributes stress more evenly during ironing. This curvature geometry prevents sudden material crushing that would occur with sharper edges, reducing residual compressive stress while maintaining productivity
3Manufacturing precision
If the clearance between punch and die is narrow, then the thickness precision is improved, but the load on surface treated layer increases
Solution Approach 1:
The invention changes the die geometry parameters (curvature radius and skewness) to optimize the stress distribution during ironing. These parameter changes allow for effective thickness control while reducing the peak load on the surface treated layer compared to conventional sharp-edged dies
Solution Approach 2:
The curved shoulder portion creates a more gradual contact zone between the die and workpiece during ironing. This curvature distributes the applied force over a larger area and longer duration, reducing peak loads on the surface treated layer while still achieving the required thickness precision through the narrow clearance
Data Source
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AI summary
An ironing mold according to the present invention is provided with a punch, and a die which forms a pushing hole with respect to the punch. When the skewness Rsk of a surface treated metal plate is less than -0.6 and no less than -1.3, then the curvature radius of a shoulder portion of the die and a clearance between a radius end and the punch are determined such that Y, which is expressed by {(tre - Cre)/tre} × 100, and X, which is expressed by r/tre, satisfy 0 < Y ≤ 18.7X - 6.1, X satisfies X ≥ 0.6 and r satisfies r ≤ 0.5h.