Press-Formed Bulging Parts With Bent Flanges to Suppress Springback
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Solution Overview
Problem
Existing press-forming methods for high-strength steel sheets suffer from significant springback, leading to defects in welding and appearance quality, particularly in low-rigidity parts with varying stress states and complex shapes, which conventional stress reduction methods fail to adequately address.
Innovation Solution
A press-forming method that involves folding the flange of excess material to form straight sides, preferably in an L or Z shape, and holding the bent flange portion between dies to suppress material inflow, enhancing rigidity and reducing springback through bending and unbending resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional press-forming methods are used for high-strength steel sheets, then material strength and rigidity are improved, but springback increases causing poor shape fixability
Solution Approach 1:
The method applies preliminary compressive stress to the flange portion before final press forming by forming an intermediate product with a smaller radius of curvature. This preliminary action creates a stress state that counteracts the springback tendency during subsequent forming, improving shape fixability while maintaining material strength
Solution Approach 2:
The method changes the radius of curvature parameter in the intermediate product to be smaller than the final product shape. This parameter change creates a stress distribution that, when released during final forming, produces compressive stress in the flange portion to suppress springback
2Manufacturing precision
If stress reduction methods are applied to suppress springback, then shape fixability improves, but material rigidity may be compromised
Solution Approach 1:
The method applies stress reduction measures locally to the flange portion rather than uniformly across the entire sheet. By forming an intermediate product with specific curvature characteristics, compressive stress is generated specifically in the flange portion where springback occurs, without compromising the overall material rigidity
3Manufacturing precision
If intermediate products are formed with smaller radius of curvature, then springback is reduced, but forming complexity increases
Solution Approach 1:
The intermediate product with smaller radius of curvature serves as a preliminary form that is subsequently expanded to the final shape. This preliminary action simplifies the overall process by pre-establishing the stress distribution needed for springback suppression, making the final forming step more controlled and predictable
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 effectively suppresses springback, improves material yield, and enhances the accuracy of press-formed products by minimizing distortion and waste, allowing for precise final product shaping without distortion.
Implementation Method 1
suppress material inflow during a second press forming by bending and unbending resistance of the bent flange portion
Implementation Method 2
press forming a sheet-shaped material into a press-formed product
Data Source
Figure 1(a)~2(i)
Figure 3~5
Figure 6~7
AI summary
Proposed is a method for manufacturing a press-formed product, which is used in manufacturing a press-formed product with a bulging portion from a sheet-shaped material including a blanking step of blanking from the sheet-shaped material into a shape in which an excess material portion is added to the contour outline of a developed shape of the press-formed product, a first pressing step of folding the excess material portion to form straight sides into an intermediate formed product with a bent flange portion, a second pressing step of performing press forming including bulging in which the bulging portion is provided on the intermediate formed product, and a trimming step of trimming the excess material portion. Provided also are a blank material that includes excess material portion to be folded to form straight sides circumscribed around or spaced apart from a contour outline of a developed shape of the press-formed product, and an intermediate formed product that includes excess material portion including a bent flange portion folded to form straight sides.