Structural Member Flange Forming to Prevent Corner R Cracks
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Solution Overview
Problem
Existing methods for producing structural members for automobiles, such as those with T-shaped joints, often result in cracks in the flanges due to sharp corner R portions, especially when using high-strength steel sheets or 6000 series aluminum alloy sheets with limited elongation.
Innovation Solution
A producing method that shapes a structural member using a die with a first lower die for the member body and first flange, and a second lower die for the second flange, allowing for a flow of material in the second flange without initial restraint, thus suppressing crack generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the curvature radius of the corner R portion is reduced to 20.0 mm or less to improve spatial allocation and member rigidity, then the degree of freedom of spatial allocation is increased and member rigidity is improved, but a crack is easily generated in the second flange
Solution Approach 1:
The patent applies preliminary action by performing a first shaping step before the second shaping step. In the first shaping step, convex-shaped portions are formed in the vertical portion of the top plate adjacent to the horizontal portions, and a curved R portion is formed to raise the connection portion between the vertical wall and flange. This preliminary preparation of the metal sheet structure enables the subsequent second shaping step to achieve sharp corner R portions (20.0 mm or less) without generating cracks in the second flange, thus resolving the contradiction between member rigidity and crack resistance
Solution Approach 2:
The patent segments the shaping process into two distinct steps: a first shaping step that forms convex-shaped portions and preliminary curved R portions, and a second shaping step that crushes these portions to create the final sharp corner R portions (20.0 mm or less). This segmentation allows the process to achieve both sharp corners for rigidity and crack-free formation for reliability by preparing the material structure in advance
2Device complexity
If a common lower die is used to shape the outward flanges and other portions to simplify the device structure, then the device complexity is reduced, but a crack is easily generated in the second flange due to simultaneous restraint
Solution Approach 1:
The patent segments the lower die into two separate components: a first lower die for shaping the member body and first flange, and a second lower die for shaping the second flange. This segmentation allows the second flange to be shaped without initial restraint from the first lower die, preventing crack generation while maintaining a relatively simple overall device structure. The separate second lower die provides the necessary freedom for material flow in the second flange region
Solution Approach 2:
The patent applies local quality by providing different die structures for different regions of the workpiece. The first lower die shapes the member body and first flange, while the second lower die specifically shapes the second flange with appropriate clearance. This localized differentiation allows each region to be shaped under optimal conditions, preventing cracks in the second flange while maintaining overall structural simplicity
3Reliability
If intermediate trimming is performed to remove cracked portions to improve reliability, then crack-free components are obtained, but the productivity is reduced due to additional processing steps
Solution Approach 1:
The patent applies preliminary anti-action by implementing a specific shaping methodology that prevents crack generation in the first place. Through the first shaping step that forms convex-shaped portions and preliminary curved R portions, and the second shaping step that carefully crushes these portions with appropriate die clearance, the process eliminates the harmful cracking effect before it occurs. This prevents the need for subsequent trimming operations, maintaining high productivity while ensuring flange integrity
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 crack generation in the flanges, eliminates the need for intermediate trimming, and produces structural members with high strength, small curvature radius of corner R portions, and reduced dimensional constraints.
Implementation Method 1
press working on metal sheets
Data Source
AI summary
A method for producing a structural member (10) includes a preparation step of preparing a starting material (M), and a shaping step of shaping the starting material (M) into the structural member (10) by using a die (20). The structural member (10) includes a member body (11), a first flange (12), and a second flange (13). The die (20) includes an upper die (23), a first lower die (21) for shaping the member body (11) and the first flange (12), and a second lower die (22) for shaping the second flange (13). The shaping step includes a first step that does not sandwich the starting material (M) between the upper die (23) and the second lower die (22), while sandwiching the starting material (M) between the upper die (23) and the first lower die (21), and a second step of shaping the second flange (13) by sandwiching the starting material (M) between the upper die (23) and the second lower die (22) after the first step.