Automotive Joint Structure With Continuous Flange for High-Strength Steel
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Solution Overview
Problem
Existing joint structures for automotive structural parts, particularly those using high-strength steel sheets, face issues with stiffness reduction due to hole or cutout provisions for preventing fracture, and lack effective methods for forming flange portions at longitudinal ends for intersecting connections.
Innovation Solution
A joint structure formed by bending a metal sheet with vertical rib portions and an outward-directed flange portion continuously shaped along side edges, where the flange portion is formed by overlapping and bending parts of the metal sheet, preventing stretch flanging deformation and allowing for continuous formation along side edges for improved stiffness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-strength steel sheet is used to increase safety at automotive collision, then strength is improved, but ductility deteriorates making the material difficult to manufacture by stretch flanging deformation
Solution Approach 1:
The flange portion is divided into multiple segments: a first flange portion extending from the top portion, second flange portions extending from side wall portions, and a corner portion connecting them. This segmentation allows each part to be formed by bending rather than stretch flanging, making high-strength steel sheets manufacturable while maintaining the continuous flange structure for strength.
2Stability of the object's composition
If a corner portion at continuous flange is formed by stretch flanging deformation to create a continuous flange structure, then the flange portion can be continuously formed along side edges, but fracture occurs when using high-strength steel sheets with poor ductility
Solution Approach 1:
Instead of forming the corner portion by stretch flanging deformation (conventional method), the invention inverts the approach by forming it through bending operations. The first flange portion and second flange portions are bent to meet and connect, creating the corner portion without stretch flanging, thus preventing fracture while achieving continuous flange formation.
3Reliability
If an opening part or cutout is provided at the corner portion to prevent fracture, then manufacturing reliability is improved, but stiffness of the joint portion largely decreases
Solution Approach 1:
The invention performs preliminary bending actions to form the first flange portion and second flange portions before they meet at the corner portion. By pre-forming these portions through bending rather than attempting stretch flanging of the entire continuous flange, the corner portion can be connected without requiring opening parts or cutouts, thus maintaining both fracture prevention and stiffness.
4Strength
If overlapping parts of metal sheet are provided between top portion and side wall portion to increase component strength, then strength at collision is improved, but interference occurs when forming flange portions at longitudinal ends for intersecting connections
Solution Approach 1:
The invention resolves the interference issue by utilizing the vertical dimension through bending operations. The first flange portion is bent upward from the top portion, and second flange portions are bent outward from side wall portions, allowing them to meet and connect in three-dimensional space without interfering with the overlapping structure between top and side wall portions.
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 solution enhances the stiffness and strength of joint portions by allowing the use of high-strength steel sheets with low ductility, improving resistance to axial loads and 3-point bending deformations, while preventing fracture and enabling efficient manufacturing processes.
Implementation Method 1
formed by bending one metal sheet
Data Source
Figure 1~2(b)
Figure 3(a)~4
Figure 5(a)~5(c)
AI summary
An automotive-structural-part joint structure 1 according to the present invention is formed by bending one metal sheet, includes a top portion 3 and a pair of side wall portions 5, is provided at an end part of an automotive structural part 110 in a longitudinal direction, joins to an automotive structural part 120 in an intersecting direction, and includes a pair of vertical rib portions 9 standing upward from both side ends 3b of the top portion 3, and an outward-directed flange portion 11 continuously formed along a side edge on an end part side where joining to the automotive structural part 120 occurs, each of the vertical rib portions 9 is formed by overlapping a part of the metal sheet, and the flange portion 11 is constituted by a flange portion adjacent to top 11a extending upward from the top portion 3, a flange portion adjacent to side wall 11b laterally extending from each of the side wall portions 5, and a vertical-rib flange portion 11c laterally extending from each vertical rib portion 9.