Embossed Press Forming of Hat-Section Steel for Crash Strength
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Solution Overview
Problem
High-strength steel sheets used in vehicle components face challenges such as shape fixation failure and reduced ductility during press forming, making it difficult to achieve both lightweight body and enhanced safety performance, while existing methods like hot press forming and induction hardening are limited in application and efficiency.
Innovation Solution
A press forming method that involves producing an intermediate molding with a ridge in a predetermined part of the workpiece, repeatedly shaping it into a final form to work-harden the part without annealing, enhancing deformation strength and impact energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-strength steel sheet is used to improve vehicle safety performance, then strength and crash safety are improved, but shape fixation failure and wrinkle occur during press forming
Solution Approach 1:
The patent applies local heating to raise the temperature of the steel sheet in the ridge portion to Ac1 transformation point or higher before press forming. This temperature change modifies the material properties, allowing high-strength steel to be formed without excessive spring-back and shape fixation failure, thus resolving the contradiction between strength and manufacturing precision
2Strength
If high-strength steel sheet is used to improve vehicle safety performance, then strength is improved, but ductility decreases leading to breakage risk
Solution Approach 1:
By locally heating the ridge portion to Ac1 transformation point or higher, the patent temporarily changes the material state to improve ductility during forming, reducing breakage risk while maintaining high strength in the final product
3Productivity
If conventional press forming is used for high-strength steel sheet, then productivity is maintained, but spring-back occurs reducing shape accuracy
Solution Approach 1:
The patent introduces local heating as a preliminary step before conventional press forming. This parameter change (temperature increase) reduces spring-back during forming, improving shape accuracy while maintaining the efficiency of conventional press forming equipment and processes
4Strength
If hot press forming or induction hardening is applied to enhance crash safety performance, then deformation strength is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies heating locally only to the ridge portion where it is most needed, rather than heating the entire component. This localized approach reduces energy consumption and simplifies equipment requirements compared to conventional hot press forming, while still achieving the desired deformation strength enhancement
Solution Approach 2:
The patent performs local heating as a preliminary action before press forming, preparing the material in advance to reduce spring-back and improve formability. This preliminary treatment simplifies the overall process by enabling the use of conventional press forming equipment without requiring complex integrated heating systems
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
This method effectively increases the deformation strength and impact energy absorption of vehicle components without annealing, enabling improved crash safety performance and weight reduction while maintaining manufacturing efficiency.
Implementation Method 1
press forming the intermediate molding into a final shape, to thereby substantially thicken and work-harden the predetermined part of the workpiece
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The present invention relates to a press forming method characterized by comprising: a first step of producing an intermediate molding (100B) by forming one or more embossments (B) in a predetermined part of a sheet metal (100), a second step of press forming the intermediate molding (100B) between a die (2) and a punch (1), while pushing the punch (1) into the die (2) by means of a relative motion of the die (2) and the punch (1), so as to shape the intermediate molding (100B) into a final shape (100A), and flattening and thickening the part having the embossments (B) provided therein, to thereby work-harden the part, wherein the final shape (100A) has a hat-like cross sectional shape, the hat-like cross sectional shape having a pair of flanges (100a) and vertical walls (100b) and ridges (100d) and a ceiling (100c).