Curved Blank Edge Geometry for Crack-Resistant Press Forming
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Solution Overview
Problem
Existing methods for manufacturing T-shaped profile components using high tensile sheet steel face issues with cracking, particularly at the boundary portions between straight-line shaped adjacent edges and curved excess portions, leading to top plate edge cracking during the free bending process.
Innovation Solution
A blank configuration with a top plate and flanges, where the top plate edges are curved and include convex and concave portions to smoothly connect with the flat pattern edge, reducing localized sheet thickness and preventing edge cracking by allowing uniform in-plane movement during pressing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressing employing drawing is used to manufacture T-shaped profile components, then creasing is suppressed, but a wide trim region is required at the periphery, reducing yield and increasing manufacturing cost
Solution Approach 1:
The patent changes the pressing method from drawing to free bending, and modifies the blank edge geometry from straight to curved with specific radius constraints (R1 ≥ 0.05t, R2 ≥ 0.1t), enabling crack suppression without requiring wide trim regions, thus improving yield while maintaining reliability
2Reliability
If metal sheets with excellent ductility but low strength are used in blanks, then creasing and cracking are prevented, but sheet thickness must be increased to secure strength, causing weight and cost increase
Solution Approach 1:
The patent changes the material parameter from low-strength high-ductility steel to high tensile sheet steel, and modifies the geometric parameters of the blank edges (curved shapes with specific radii), achieving crack prevention through geometry optimization rather than material substitution, thus reducing weight while maintaining reliability
Solution Approach 2:
The patent applies different curvature radii at different locations of the blank edge (R1 at adjacent edges, R2 at excess portion edges), creating local geometric quality variations that optimize stress distribution specifically at critical regions, enabling crack suppression without increasing overall material thickness
3Strength
If high tensile sheet steel with low ductility is employed, then weight and strength are improved, but creases, cracking, and other defects occur during pressing
Solution Approach 1:
The patent modifies the geometric parameters of the blank (curved edges with specific radii R1 and R2) to compensate for the low ductility of high tensile sheet steel, enabling defect-free pressing while maintaining the strength benefits of the high-strength material
4Reliability
If excess portions are provided to edges at both length direction ends of the blank, then top plate edge cracking is avoided, but boundary portions between adjacent edges and excess portions experience large sheet thickness reduction, causing cracking
Solution Approach 1:
The patent optimizes the curvature radius parameters (R1 ≥ 0.05t, R2 ≥ 0.1t) of the blank edges to balance two competing requirements: providing enough excess material to prevent edge cracking while controlling the sheet thickness reduction at boundary portions to prevent cracking, achieving both goals through precise geometric parameter control
Data Source
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AI summary
A blank for forming a pressed article, the blank including a flat pattern edge configuring an edge on one length direction side of the blank, and an excess portion formed at the flat pattern edge. An edge of the excess portion includes a first convex portion that protrudes toward the one length direction side of the blank with respect to the flat pattern edge, a first concave portion that is adjacent to the first convex portion at a width direction outer side of the blank, that is formed in a concave shape opening toward the one length direction side of the blank, and that connects the flat pattern edge and the first convex portion together, and a second concave portion that is adjacent to the first convex portion at a width direction inner side of the blank, that is formed in a concave shape opening toward the one length direction side of the blank, and that connects the flat pattern edge and the first convex portion together.