Two-Step Press Forming for Stepped Panels Without Wrinkles
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Solution Overview
Problem
Existing methods for producing press-formed products with stepped sections using high-strength metal plates often result in wrinkles or cracks due to low ductility, and previous solutions do not effectively address the production of such products with top plate sections having stepped sections.
Innovation Solution
A two-step press-forming method using first and second press tooling to form an intermediate product with temporary flange and vertical wall sections, where the temporary ridge section is moved toward the temporary flange section in the second step, minimizing shearing strain and preventing wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If draw forming is used to form stepped sections to avoid wrinkles, then wrinkle prevention is improved, but cracking occurs due to low ductility of high-strength metal plates
Solution Approach 1:
The forming process is divided into two distinct stages: first forming the stepped section, then forming the vertical wall section. This segmentation allows each stage to address specific geometric requirements without subjecting the high-strength metal plate to excessive shearing strain that would cause cracking, while still preventing wrinkles through controlled material flow in each stage.
Solution Approach 2:
The stepped section is formed in advance before forming the vertical wall section. This preliminary action prepares the material distribution and stress state appropriately, reducing the risk of cracking during subsequent forming operations on high-strength metal plates while maintaining wrinkle prevention capabilities.
2Strength
If high-strength metal plates are used to improve vehicle body strength and reduce weight, then tensile strength is improved, but ductility decreases leading to cracking during forming
Solution Approach 1:
The forming process is divided into two distinct stages: first forming the stepped section, then forming the vertical wall section. This segmentation allows each stage to address specific geometric requirements without subjecting the high-strength metal plate to excessive shearing strain that would cause cracking, while still preventing wrinkles through controlled material flow in each stage.
Solution Approach 2:
The forming parameters such as punch speed, pressure, and tooling geometry are optimized for each stage to match the material characteristics of high-strength metal plates. This allows the material to undergo necessary deformation while maintaining integrity, achieving both high strength utilization and forming quality.
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 prevents wrinkles and cracks in press-formed products with stepped sections, even when using high-strength metal plates, by reducing shearing strain and allowing for the formation of products with complex geometries without material flow issues.
Implementation Method 1
a first pressing step in which a first press tooling forms an intermediate formed product from a processed material
Implementation Method 2
forming is performed such that the temporary ridge section is moved toward the temporary flange section with at least part of the top plate section of the intermediate formed product restricted
Data Source
AI summary
A method for producing a press-formed product includes a first pressing step and a second pressing step. In the first pressing step, an intermediate formed product is formed from a processed material by using first press tooling. The intermediate formed product includes a stepped section of a top plate section, a temporary vertical wall section adjacent to the top plate section via a ridge section and having at least part of the shape of the vertical wall section, and a temporary flange section adjacent to the temporary vertical wall section via a temporary ridge section. In the second pressing step, the press-formed product is formed from the intermediate formed product. In the second pressing step, forming is performed such that the temporary ridge section is moved toward the temporary flange section with at least part of the top plate section of the intermediate formed product restricted.