Curved Hollow Structural Member Bending Rigidity
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Solution Overview
Problem
Conventional hollow structural members with straight configurations, used in vehicles, lack desired bending strength characteristics and have limited application due to their rigidity issues under bending loads, particularly in streamlined vehicle bodies.
Innovation Solution
A formed body with an open cross-sectional shape and inwardly directed flanges that are curved, allowing for enhanced rigidity during bending deformation, produced through a multi-step press forming process using pad draw forming and pad bend forming techniques, enabling the use of high-tensile strength materials like steel with 440 MPa or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a straight-shaped hollow structural member is used, then the manufacturing process is simple, but the bending strength characteristics are insufficient and application range is limited
Solution Approach 1:
The patent applies curvature to the hollow structural member by forming the body portion in a curved shape rather than straight. This curvature enhances the bending strength characteristics and allows the member to be used in streamlined vehicle bodies, directly resolving the contradiction between manufacturing simplicity and bending strength by introducing a geometric modification that improves performance while remaining compatible with press forming processes.
2Ease of manufacture
If conventional press forming method is used, then the production process is simple, but inwardly directed flanges cannot be formed
Solution Approach 1:
The patent divides the press forming process into multiple sequential steps: first forming the body portion with the open cross-sectional shape, then subsequently forming the flanges in separate operations. This segmentation of the forming process enables the creation of inwardly directed flanges that would be impossible with conventional single-step press forming, while still using standard equipment and methods.
3Strength
If high-tensile strength material is used, then weight reduction and safety are improved, but forming difficulty increases
Solution Approach 1:
The multi-step forming process segments the deformation into manageable stages, allowing high-tensile strength materials to be formed successfully. By forming the body portion first and then the flanges separately, each step involves controlled deformation that prevents excessive stress concentration, enabling the use of high-strength materials that would be difficult to form in a single operation.
Solution Approach 2:
The patent performs preliminary forming of the body portion before forming the flanges. This preliminary action prepares the material in a state that facilitates subsequent flange formation, reducing the overall forming difficulty even when using high-tensile strength materials. The sequence of operations is optimized to manage material behavior throughout the forming process.
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 formed body achieves excellent rigidity and energy absorption capabilities, expanding its application range, including use in vehicle components like front pillars and side members, while maintaining cost-effectiveness and preventing wrinkles or cracks during production.
Implementation Method 1
a formed body made of steel having tensile strength of 440 MPa or more, the formed body including: a body portion having an open cross-sectional shape... the body portion and the at least one flange curve so as to conform to each other
Data Source
AI summary
A formed body 1 includes a first flange 3, a body portion 100 (a first vertical wall portion 4, a top plate portion 5, a second vertical wall portion 6), and a second flange 7, and the formed body 1 is made of steel having tensile strength of 440 MPa or more. The first flange 3 extends toward the second flange 7 from an edge portion of the first vertical wall portion 4. The first flange 3 and the body portion 100 curve so as to conform to each other as viewed from the direction orthogonal to the top plate portion 5.