Hat-Section Press Blank Layout for Crack and Spring-Back Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing vehicle frame components with hat-shaped cross-sectional shapes and curved portions face issues such as cracks, wrinkles, and excessive spring-back due to material ductility limitations and stress differences, particularly with high tensile strength steel sheets, leading to poor dimensional accuracy.
Innovation Solution
A press forming method involving rotational displacement of material during the forming process to balance material distribution, combined with projection and bead shapes, to reduce defects and stress differences, using a press forming device with specific die configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high tensile strength steel sheet is used to achieve vehicle lightweighting and collision safety, then strength is improved, but ductility decreases and spring-back becomes large
Solution Approach 1:
The patent applies preliminary action by providing a projection portion on the metal sheet before press forming. This projection portion is formed in advance at the curved inner side of the curved portion, and during press forming, it rotates and fills material deficiency, preventing cracks and reducing spring-back. The preliminary structure modification enables the high strength steel sheet to achieve the desired curved shape without forming defects.
2Shape
If metal sheet is press formed into curved component shape, then desired shape is achieved, but crack occurs at flange portion on curved inner side due to shortage of material ductility
Solution Approach 1:
The projection portion is provided in advance at the curved inner side before press forming. During the forming process, this projection rotates and supplies material to the flange portion on the curved inner side, preventing material deficiency and crack formation. This preliminary structural modification ensures material availability during forming.
Solution Approach 2:
The patent introduces asymmetry by providing a projection portion only at the curved inner side (where material deficiency occurs) rather than uniformly distributing material features. The projection has specific dimensional parameters (height h1 and width w1) that create an asymmetric material distribution, enabling targeted material flow to prevent cracks at the critical curved inner side location.
3Shape
If metal sheet is press formed into curved component shape, then desired shape is achieved, but wrinkle occurs at flange portion on curved outer side due to material excess
Solution Approach 1:
The projection portion is formed in advance at the curved inner side, which during press forming rotates and redistributes material. This preliminary structure controls material flow to prevent both material deficiency at the inner side and material excess at the outer side, thereby preventing wrinkles on the curved outer side while achieving the desired shape.
4Productivity
If conventional press forming is performed on metal sheet with curved portions, then component is produced, but spring-back exceeding predetermined amount occurs after release, causing lowered dimensional accuracy
Solution Approach 1:
The projection portion is provided in advance to modify the stress distribution in the metal sheet before forming. During press forming, the projection rotates and relieves stress concentration, particularly at the curved portions. This preliminary structural modification reduces spring-back after release, improving dimensional accuracy while maintaining production efficiency.
Solution Approach 2:
The patent changes the physical parameters of the metal sheet by introducing a projection portion with specific dimensions (height h1, width w1) and position (at the curved inner side). This parameter modification alters the stress distribution and material flow characteristics during forming, reducing spring-back and improving dimensional accuracy of the final component.
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 reduces cracks, wrinkles, and spring-back in press-formed components, improving dimensional accuracy and stability, especially for high tensile strength steel sheets.
Implementation Method 1
press forming a metal sheet into a vehicle frame component
Implementation Method 2
a spring-back or the like exceeding a predetermined amount easily occurs in the formed product after release
Data Source
Figure 1A~1C
Figure 2A~2J
Figure 3
AI summary
There is provided a technology capable of further reducing forming defects such as cracks, wrinkles, and lowered dimensional accuracy in a press-formed component having a hat-shaped cross-sectional shape and including one or more curved portions as seen in a plan view. A metal sheet (10) for press forming has a shape such that, in a developed shape of a press-formed component shape (1) developed on a plane in such a manner that, in a region corresponding to a curved portion (1A), a line length of a position corresponding to a ridge line between a top sheet portion (2) and a vertical wall portion (3) in the press-formed component shape (1) is equal to a line length of the ridge line, a boundary position between the region corresponding to the curved portion (1A) and an other region in the region corresponding to the curved portion (1A)is rotationally displaced in-plane around a rotational center (P) set at a position on a curved recessed side rather than a position corresponding to a ridge line between the top sheet portion (2) and the vertical wall portion (3) on the curved recessed side, in a direction in which a line length of an outer edge of a position to be formed into the flange portion (4) on the curved protruding side in the region corresponding to the curved portion (1A) approaches a line length of an outer edge of the flange portion (4) on the curved protruding side in the press-formed component shape.