Two-Step Press Forming for Curved Hat-Section Warpage Control
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Solution Overview
Problem
Existing press forming methods for vehicle body components with hat-shaped cross-sectional shapes and curved parts suffer from issues of warpage and torsion due to springback, leading to poor dimensional accuracy, especially when using high tensile strength steel.
Innovation Solution
A two-step press forming process using a shape correction die that adjusts the angles and radii of curvature of vertical wall parts relative to the top sheet part to correct warpage and torsion, employing different die configurations for lifted and dropped end portions to suppress longitudinal warpage and torsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high tensile strength steel is used to reduce vehicle body weight and improve collision safety, then strength is improved, but ductility deteriorates causing cracks to occur easily
Solution Approach 1:
The patent applies preliminary action by performing shape correction in advance through a two-step press forming process. The first step corrects the cross-sectional shape while the second step corrects longitudinal warpage and torsion before final assembly, preventing crack occurrence in high tensile strength steel components
2Strength
If high tensile strength steel is used, then strength is improved, but dimensional accuracy deteriorates due to wrinkles and springback
Solution Approach 1:
The patent segments the press forming process into two distinct steps: first forming for cross-sectional shape and second forming for longitudinal shape correction. This segmentation allows targeted correction of different deformation modes, improving dimensional accuracy while maintaining high strength
Solution Approach 2:
The patent performs preliminary shape correction in the first forming step to establish the cross-sectional geometry, then performs additional correction in the second step for longitudinal warpage and torsion, achieving high dimensional accuracy through staged intervention
3Device complexity
If a single-step press forming method is used, then device complexity is reduced, but manufacturing precision deteriorates due to warpage and torsion in elongated components
Solution Approach 1:
The patent divides the forming process into two steps with different die configurations: first forming for cross-sectional shape and second forming for longitudinal correction. This segmentation enables precise control of warpage and torsion in elongated components
Solution Approach 2:
The patent applies local quality by using different die configurations for different regions and stages: the first die for cross-sectional forming and the second die with different configuration for longitudinal warpage and torsion correction, optimizing each step for its specific function
4Reliability
If flange parts are bent to reduce torsion stress, then reliability is improved, but manufacturing precision deteriorates due to insufficient effect on longitudinal warpage
Solution Approach 1:
The patent segments the correction functions: the first forming step addresses cross-sectional shape and torsion through flange bending, while the second forming step specifically addresses longitudinal warpage and torsion, achieving comprehensive dimensional control
Solution Approach 2:
The patent changes forming parameters between steps: the first forming uses parameters optimized for cross-sectional shape and torsion reduction, while the second forming uses different parameters optimized for longitudinal warpage and torsion correction
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 method effectively suppresses warpage and torsion in formed products, enhancing dimensional accuracy and stability of components with hat-shaped cross-sectional shapes and curved parts.
Implementation Method 1
springback (elastic recovery)
Implementation Method 2
the cross section is changed due to the springback (elastic recovery)
Data Source
Figure 1A~1C
Figure 2~3
Figure 4A~4D
AI summary
Warpage or torsion in a longitudinal direction is suppressed when an elongated curved component is manufactured by press forming. A method for manufacturing a pressed component includes a first step (2) of press forming a metal sheet (1) in a desired component shape using a first die, and a second step (3) of press forming a formed product (10) using a second die after the first step (2). In the second step (3), a cross section of a bent part (10D) and a vertical wall part (10B) are controlled to be opened depending on warpage at longitudinal end portions of the component by elastic recovery due to release from the first die, thereby suppressing the warpage.