Press Forming Tool for Flange Wrinkle and Fracture Suppression
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Solution Overview
Problem
Existing press forming methods struggle to suppress wrinkles and fractures in the flange portion of automotive parts made from high-strength steel sheets, particularly when thinning is applied for weight reduction.
Innovation Solution
A press forming tool and method that utilize an upper die with convex and concave outer edge flange forming portions, along with a lower pad, to form a torsional shape portion initially and then convert it into a flange portion, thereby managing material flow to prevent wrinkles and fractures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wrinkle suppression pad is used to hold down the inside of the product, then wrinkles and stretch flange fractures inside the product are suppressed, but the technique cannot be applied to shapes having occurrence of wrinkles or fractures in the flange portion itself
Solution Approach 1:
The upper die is segmented into multiple flange forming portions (first, second, and third convex outer edge flange forming portions) that can independently control different regions of the flange portion. This segmentation allows each portion to address specific wrinkle or fracture risks in different areas, making the technique applicable to complex flange geometries while maintaining suppression effectiveness.
Solution Approach 2:
Each convex outer edge flange forming portion is designed with specific geometric characteristics (protrusion distances, curvature radii, orientations) tailored to the local requirements of different flange regions. The first portion handles one area, the second portion another, and the third portion connects them, providing locally optimized wrinkle and fracture suppression throughout the entire flange portion.
2Weight of moving object
If high-strength steel sheets are used for weight reduction, then automotive body weight is reduced, but the sheets tend to cause fracture during material processing
Solution Approach 1:
The convex outer edge flange forming portions are designed to gradually guide and control material flow during flange formation. By pre-planning the geometry of these forming portions (protrusion distances, curvature radii), the material flow is controlled in advance to prevent stress concentration and fracture, allowing high-strength steel sheets to be formed without fracture while maintaining weight reduction benefits.
Solution Approach 2:
The forming process dynamically controls material flow through the sequentially arranged convex outer edge flange forming portions. Each portion progressively shapes the flange, allowing the material to flow adaptively rather than experiencing sudden stress changes. This dynamic control prevents fracture in high-strength steel sheets while enabling the weight reduction achieved through their use.
3Weight of moving object
If thinning of the sheet is performed for further weight reduction, then weight is reduced, but the likelihood of occurrence of buckling and wrinkles increases
Solution Approach 1:
The convex outer edge flange forming portions are specifically designed with optimized geometric parameters (protrusion distances L1, L2, L3 and curvature radii R1, R2, R3) for each region of the flange. This local optimization ensures that even thinned sheets maintain sufficient support and controlled material flow in each area, preventing buckling and wrinkles while preserving the weight reduction achieved through thinning.
4Reliability
If multiple flange forming portions are used to control material flow, then wrinkles and fractures are suppressed, but the device complexity increases
Solution Approach 1:
Multiple convex outer edge flange forming portions are merged into a single integrated upper die structure. Rather than using separate tools or stages, all forming portions (first, second, and third) are combined in one die, allowing simultaneous control of material flow across different flange regions. This merging achieves wrinkle and fracture suppression while avoiding the complexity of multiple separate devices or processing stages.
Solution Approach 2:
The upper die with multiple convex outer edge flange forming portions serves multiple functions simultaneously: it forms the flange portion geometry, controls material flow in different regions, and suppresses both wrinkles and fractures. This multi-functionality achieves comprehensive defect suppression without requiring additional specialized devices, thereby limiting the increase in device complexity.
Data Source
AI summary
A press forming tool is configured to form a press forming part including: a top portion having a convex and concave outer edge part; and a flange portion. The press forming tool includes: an upper die and a lower die; and a lower pad and an upper pad, which sandwich a blank in cooperation with the upper die and the lower die, in which, during an initial stage of forming, the flange portion is formed on the convex outer edge part, and a torsional shape portion having a torsional shape toward the concave outer edge part is formed continuously from the flange portion, and during a late stage of forming, the torsional shape portion is formed into the flange portion, and the flange portion is formed in the concave outer edge part so as to achieve formation of a target shape.