Patchwork Blank Bending Sequence to Prevent Joint Cracking
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Solution Overview
Problem
Existing press molding techniques concentrate bending stress at the joint portion between the basework and patchwork, leading to potential cracking or bending during the formation of thickened portions in press-molded articles.
Innovation Solution
The method divides the bending process into separate stages for the thickened and non-thickened portions, using a first mechanism for vertical bending and a second mechanism for inclined bending, facilitated by a cam mechanism, to distribute stress evenly and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single bending process is applied to both thickened and non-thickened portions, then the manufacturing process is simple, but bending stress concentrates at the joint portion causing cracking or unintended bending
Solution Approach 1:
The patent divides the blank into thickened portions and non-thickened portions, and applies different bending processes to each segment. The thickened portions undergo bending in a first direction (e.g., vertical pressing), while the non-thickened portions undergo bending in a second direction different from the first (e.g., inclined pressing). This segmentation prevents stress concentration at joint portions by treating each region according to its structural characteristics, thereby maintaining joint integrity while keeping the overall process manageable.
2Reliability
If different bending steps are applied to thickened and non-thickened portions, then stress distribution is improved and cracking is prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The patent performs preliminary classification of the blank into thickened and non-thickened portions before the bending process. By pre-identifying which regions require which bending direction, the system can apply the appropriate bending sequence without requiring complex real-time decision-making during pressing. The thickened portions are bent first in the first direction, followed by bending of non-thickened portions in the second direction, which simplifies process control while maintaining reliability.
Solution Approach 2:
The patent employs a dynamic bending process where the pressing direction changes sequentially rather than simultaneously. The first bending direction is applied to thickened portions, then the second bending direction is applied to non-thickened portions. This dynamic approach allows the system to adapt to different structural requirements at different stages, achieving reliable stress distribution without requiring overly complex simultaneous multi-directional pressing mechanisms.
3Ease of manufacture
If uniform pressing is applied across the entire blank, then the equipment and process are simple, but accurate shaping of complex forms with multiple bent portions is difficult
Solution Approach 1:
The patent applies the principle of local quality by prescribing different bending directions for different regions of the blank. Thickened portions are subjected to bending in a first direction optimized for their structural characteristics, while non-thickened portions are subjected to bending in a second direction optimized for their characteristics. This localized approach enables accurate shaping of complex forms with multiple bent portions, as each region receives the appropriate bending treatment rather than uniform pressing.
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 prevents unintended cracking or bending at the joint portion, allowing for accurate shaping of complex forms like automobile B-pillars with high strength and accuracy.
Implementation Method 1
The second mechanism may include a cam mechanism that converts a press load in a vertical direction of the first mechanism from a vertical direction to an inclined direction
Data Source
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AI summary
A method for manufacturing a press-molded article includes: preparing a patchwork blank 1 in which a thickened portion 4 is formed by welding patchwork 3 to basework 2; bending only the thickened portion 4 of the patchwork blank 1; and bending a portion other than the thickened portion 4 in a step different from bending of the thickened portion 4.