Closed Cross-Section Forming with Bend-Facilitating Lines
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Solution Overview
Problem
Existing methods for forming closed cross-sectional structures, such as those used in automobile parts, face challenges with material ductility issues leading to potential cracks, and high production costs due to the need for precise three-dimensional curvatures and flange formation.
Innovation Solution
A method and apparatus that utilize bend-facilitating lines with specific groove depths and widths to enable precise bending of workpiece portions along a plug's outer periphery, allowing for the formation of closed cross-sectional structures with three-dimensional curvatures, reducing production costs and preventing material cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a flat punch is used to press the connecting part from the inside to form a V-shaped bent part, then the half portions of the closed cross-sectional structure can extend upwardly, but a crack may be generated at the V-shaped bent part when material having low ductility is used
Solution Approach 1:
Bend-facilitating lines are formed in advance on the workpiece before the main forming operation. These pre-formed lines serve as guides for subsequent bending, allowing the material to deform along predetermined paths with reduced stress concentration, thereby preventing crack generation while achieving the required geometric extension
Solution Approach 2:
The forming process is divided into multiple stages: first forming bend-facilitating lines, then performing the main bending operation along these lines. This segmentation allows the complex deformation to be broken down into manageable steps, reducing the risk of material failure
2Reliability
If the end of the bent part is made to have a round shape to prevent cracking, then the half portions of the closed cross-sectional structure extend upwardly to a smaller degree, but it becomes difficult to perform welding in the next step
Solution Approach 1:
Bend-facilitating lines are pre-formed with specific geometric characteristics that allow the material to bend smoothly without sharp corners, preventing cracks while maintaining sufficient extension distance for subsequent welding operations
Solution Approach 2:
The geometry of the bent part is optimized by controlling the parameters of the bend-facilitating lines (groove depth, width, and spacing), achieving a balance between crack prevention and adequate extension for welding
3Manufacturing precision
If three-dimensionally curved shapes are formed in the pair of half portions with high precision, then closed cross-sectional structures with curvatures can be formed, but the production cost increases
Solution Approach 1:
Bend-facilitating lines are pre-formed on the workpiece surface to guide the subsequent bending operation. This preliminary marking allows for accurate three-dimensional curvature formation without requiring expensive specialized tooling or multiple iterative adjustments, thereby reducing production costs while maintaining high precision
Solution Approach 2:
The bend-facilitating lines serve as self-guides during the bending process, allowing the workpiece to follow its own pre-marked deformation paths. This eliminates the need for complex external guidance systems or expensive precision fixtures
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
Enables the formation of closed cross-sectional structures with high precision and reduced production costs, effectively addressing material limitations and precision requirements in forming automobile parts and other structural components.
Implementation Method 1
bending the bottom portions (2, 3) and the left and right side wall portions (4, 5, 6) along bend-facilitating lines G by pressing the bottom portions (2, 3) and the left and right side wall portions (4, 5, 6) against an outer periphery of a plug (20)
Data Source
Figure 1
Figure 2(a)~3(b)
Figure 4(a)~4(b)
AI summary
An object is to make it possible to easily form a plate-shaped material into a closed cross-sectional structure with high precision. In a first step of press-forming, a workpiece 1 is formed into a curved shape that has curvatures in the longitudinal direction and the width direction required for a final closed cross-sectional shape, and bend-facilitating lines G are provided at positions corresponding to bent lines in the final closed cross-sectional shape. Next, in a second step, the workpiece, which has been formed in the first step, is bent in such a direction that left and right side wall portions approach each other by clamping bottom portions 2 and 3 between a punch 15 and a pad 16 in the plate thickness direction and by pressing a punch into a space between a pair of dies 17. Next, in a third step, a plug 20 having an outer peripheral shape that is the same as the final closed cross-sectional shape is placed on the bottom portion of the workpiece, which has been formed in the second step, and the bottom portion and the left and right side wall portions are bent along the bend-facilitating lines by pressing the bottom portion and the left and right side wall portions against an outer periphery of the plug.