Press-Formed Auto Body Member With Sharp Corners and Wrinkle Control
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Solution Overview
Problem
Existing automobile body press-molded components, particularly floor cross members, face challenges in achieving high load capacity and rigidity due to large vertical wall angles, which lead to wrinkles and reduced load transfer characteristics during axial crushing, and conventional methods struggle to produce these components without wrinkles or compromising external appearance and performance.
Innovation Solution
The solution involves reducing the radius of curvature of the vertical wall angle (R) to less than or equal to 13% of the cross-sectional line length, increasing the areas of the vertical wall and floor flanges, and employing a two-step press molding process to suppress wrinkles, where the first step molds linkage portions between the vertical wall and floor flanges under arbitrary constraint conditions, and the second step forms the desired transverse cross-sectional shape with continuous top sheets and outward flanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the radius of curvature of the vertical wall angle is reduced to enhance load capacity and rigidity, then the bonding efficiency and load transfer characteristics are improved, but wrinkles occur during the press molding process
Solution Approach 1:
The press molding process is divided into two distinct steps: a first press molding step that forms the basic component shape, and a second press molding step that forms the outward flanges with small radius of curvature. This segmentation allows each step to be optimized independently, enabling the formation of sharp corners without wrinkles while achieving high load capacity.
Solution Approach 2:
The first press molding step performs preliminary forming of the component body, preparing the vertical walls and basic geometry. This preliminary action creates a stable foundation that allows the second step to focus on forming the critical outward flanges with small radius of curvature, preventing wrinkle formation during the final shaping.
2Reliability
If the radius of curvature of the vertical wall angle is reduced to improve load transfer characteristics, then the bonding efficiency is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into two press molding steps, where the first step creates the basic component structure and the second step forms the outward flanges. This segmentation simplifies each individual step while achieving the complex final geometry, allowing standard press molding equipment to be used without requiring specialized single-step tools.
Solution Approach 2:
The two-step press molding process maintains continuous useful action by forming all critical features (vertical walls, ridgelines, and outward flanges) in sequence without removing the workpiece. This continuous forming approach reduces manufacturing complexity compared to multi-stage processes involving separate operations for each feature.
Data Source
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AI summary
[Object] An issue is to provide a member that exhibits high load capacity and rigidity when joined to another member. [Solution] Provided is a member 1 having a transverse cross section that includes a top sheet 2, upper ridgelines 4, vertical walls 3, lower ridgelines 5, and floor flanges 9, and including, on at least one end portions in the extending directions of the upper ridgelines 4, a top sheet flange 11 via a top sheet ridgeline 6 and vertical wall flanges 10 via vertical wall ridgelines 7, in which the vertical wall flange 10 and the floor flange 9 are continuous, and in end portions of the upper ridgelines 4 and the lower ridgelines 5, the sum total ∑R of the radii of curvature of corner portions of the vertical walls and the sum total ∑L of the widths of the top sheet 2 and the vertical walls 3 in an end portion of the member have the relation of ∑R/∑L ≤ 0.13. The member 1 is produced by performing a first step of performing press molding on a blank 26 to form, in a shrink flange manner, flange ridgelines 8 and thereby producing an intermediate molded product 27 including at least the flange ridgelines 8 and a second step of performing press molding on the intermediate molded product 27 to produce the member 1.