Blank Preforming Shape Determination for Uniform Strain
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Solution Overview
Problem
Existing methods for improving yields and formability in press forming either result in excess metal or lowered yields due to localized strain, and there is a lack of established methods for determining preforming shapes effectively.
Innovation Solution
A method that involves determining a preforming shape by ensuring the cross-sectional line length ratio in the preforming stage is within a predetermined tolerance range of the final shape, allowing for uniform strain distribution and improved formability, which includes determining cross-sectional lines in a grid-like or radial form to achieve the desired shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow rate of material into the mold set is minimized to improve yields, then yields are improved, but the blank becomes excessively thin and develops defects such as cracks
Solution Approach 1:
The patent applies preliminary action by performing preforming before final stretch forming. The preforming step prepares the blank by creating an intermediate shape that optimizes material distribution, allowing the subsequent final forming to proceed with better material flow control. This preliminary preparation prevents both excessive thinning and cracking while maintaining high yields.
2Reliability
If drawing operations are performed to prevent cracks, then formability is improved, but yields are lowered due to excess metal
Solution Approach 1:
The patent applies parameter changes by optimizing the preforming shape parameters, specifically controlling the cross-sectional line length ratio to fall within a predetermined range (0.95-1.05). This parameter control enables the blank to achieve optimal material distribution before final forming, preventing cracks without requiring excessive drawing operations that would create excess metal and reduce yields.
3Device complexity
If press forming is performed in a single step to reduce process complexity, then device complexity is reduced, but strain becomes localized and formability deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the press forming process into two distinct stages: preforming and final stretch forming. The preforming stage creates an intermediate shape with optimized strain distribution, while the final stage completes the forming. This segmentation prevents strain localization that would occur in single-step forming, improving formability without requiring overly complex equipment.
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 approach enables high yields and improved formability by preventing cracks and wrinkles, ensuring the strain distribution is uniform throughout the final product, effectively addressing the limitations of existing methods.
Implementation Method 1
forming the blank into a preforming shape by plastic deformation and then by plastically deforming the blank into a final shape from the preforming shape
Data Source
AI summary
Provided is a method for forming a blank, the method being capable of improving both yields and formability. The method for forming a blank 1 includes forming the blank 1 into a preforming shape by plastic deformation and then plastically deforming the blank 1 from the preforming shape into a final shape. The preforming shape is determined so that, in each of cross sections in the final shape, the ratio (L1/L0) of a cross-sectional line length L1 in the preforming shape to a cross-sectional line length L0 in the final shape in the same cross section position falls within a predetermined tolerance range.