Press Forming Device for L-Shaped Hat Sections
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Solution Overview
Problem
Press-formed products with a hat-shaped cross section, particularly those used in vehicle body structural members, often experience cracks and wrinkles due to high tensile strength metal plates and deep or curved designs, which existing technologies struggle to mitigate effectively.
Innovation Solution
A press-forming apparatus and method that involves a punch, first and second blank holders, a die, a pad, and a restriction mechanism, where the first guide face of the preceding portion precedes the second guide face of the die, allowing for sequential formation of the first vertical wall and flange portions before the second vertical wall and flange portions, reducing thickness reduction and stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional press-forming methods are used on high-strength metal plates with deep or curved designs, then the desired shape can be achieved, but cracks and wrinkles occur due to high tensile strength and thickness reduction
Solution Approach 1:
The die is divided into multiple sections with different guide faces (first guide face and second guide face) that act at different stages during forming. The first guide face forms the first vertical wall portion and first flange portion, while the second guide face forms the second vertical wall portion and second flange portion. This segmentation allows progressive deformation and reduces stress concentration that would otherwise cause cracks and wrinkles.
Solution Approach 2:
The first guide face is positioned to precede the second guide face during the forming process. This preliminary action allows the first vertical wall portion and first flange portion to be formed before the second guide face acts on the metal plate. By preparing the material in advance through controlled preliminary deformation, the subsequent forming stages can proceed with reduced risk of defects.
2Strength
If high-strength metal plates are used to improve structural member strength, then the product strength increases, but the susceptibility to cracks and wrinkles during forming increases
Solution Approach 1:
The forming process uses dynamic control of blank holder positions and guide face sequencing. The first and second blank holders are positioned at different locations and act at different times during forming. This dynamic approach allows the high-strength metal plate to be deformed progressively, accommodating its high tensile strength while preventing sudden stress concentrations that would cause surface defects.
Solution Approach 2:
The process changes the sequencing and timing of when different portions of the die contact and deform the metal plate. By controlling the stroke difference between the first and second guide faces, the deformation parameters are optimized for high-strength materials. This parameter control allows thorough forming of complex shapes while maintaining surface quality.
3Manufacturing precision
If the guide faces are positioned to precede sequentially, then thickness reduction and stress concentrations are reduced, but the device complexity increases
Solution Approach 1:
The die structure merges multiple functions into a unified design. The first and second guide faces are integrated into the same die assembly, working in coordination rather than as separate operations. The blank holders and guide faces function together as an integrated system, reducing the need for additional separate mechanisms while achieving controlled sequential deformation.
Solution Approach 2:
The die design uses universal components that perform multiple functions. The guide faces serve both as forming surfaces and as positioning elements for the blank holders. The same die structure accommodates different forming stages through the sequential action of its components, reducing overall device complexity while maintaining precise thickness control.
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(f)
Figure 3(a)~3(b)
AI summary
A press-forming apparatus (20) is an apparatus for producing a press-formed product (10) having a hat-shaped cross section that has an external shape that curves in an L shape along a longitudinal direction in a planar view, and includes a punch (31), a first blank holder (32), a second blank holder (33), a preceding portion (54), a second die (53) and a pad (41). When pushing the punch (31) into a die (50) to form a metal plate (70) into the press-formed product (10), a first guide face (50c) of the preceding portion (54) precedes a second guide face (50d) of the second die (53), and thereafter sliding of the first blank holder (32) and the preceding portion (54) relative to the punch (31) is restricted and pushing of the punch (31) into the die (50) is continued in the restricted state to form the press-formed product (10). By this means, the press-formed product (10) in which cracks and wrinkles are reduced is obtained.