Press-Formed Panel Blank Sequencing to Prevent Cracks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Press-formed products, such as automobile inner panels, face issues with cracks during forming due to increased strain and ductility limitations when using thin sheets, and transfer defects due to unintended deformation during handling, leading to reduced dimensional accuracy and productivity.
Innovation Solution
A manufacturing method involving draw forming, piercing, and hole expansion forming to create a honeycomb structure with a high-rigidity shape, using a vacuum carrier machine to maintain sheet alignment and reduce deformation during transfer, and forming through-holes before stretch-forming to distribute strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If sheet thickness is reduced to achieve weight reduction, then weight decreases, but bending rigidity becomes insufficient and cracks occur during press forming
Solution Approach 1:
The invention introduces through-holes in the blank to create a segmented structure. This segmentation allows the material to deform more uniformly during press forming by providing stress relief points, preventing crack propagation while maintaining thin sheet thickness for weight reduction
Solution Approach 2:
The invention uses a porous structure (through-holes) in the blank to improve formability. The holes create a cellular architecture that enhances energy absorption and strain distribution, allowing thin sheets to undergo large deformations without cracking while maintaining adequate rigidity
2Ease of operation
If thin sheets are transferred using vacuum carrier machine, then transfer is enabled, but unintended plastic deformation occurs due to deflection from partial suction
Solution Approach 1:
The invention performs draw forming to create an intermediate shape with increased rigidity before transfer. This preliminary shaping action provides sufficient stiffness to the thin sheet to resist deflection during vacuum carrier machine transfer, preventing plastic deformation while maintaining transfer capability
Solution Approach 2:
The draw-formed intermediate shape acts as a cushioning structure that prevents excessive deflection during transfer. The pre-formed geometry distributes suction forces more evenly and provides structural support against gravitational deflection, protecting the material from damage
3Reliability
If through-holes are formed before stretch-forming, then strain is distributed and forming defects are suppressed, but additional process steps are required
Solution Approach 1:
The invention performs piercing to create through-holes before stretch-forming. This preliminary action prepares the material structure to handle subsequent large deformations by providing stress relief points, preventing crack formation and improving forming quality
Solution Approach 2:
The invention combines multiple operations (draw forming, piercing, stretch-forming) into an integrated manufacturing sequence. By merging these steps in a specific order, the process achieves high reliability in defect prevention while managing overall process complexity through systematic integration
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 suppresses forming defects and unintended deformation, ensuring high panel rigidity and dent resistance while maintaining thin sheet thickness, enhancing dimensional accuracy and productivity.
Implementation Method 1
it is conceivable to use a vacuum carrier machine to transfer a thin sheet while sucking the starting material
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for manufacturing a press-formed product is provided that can suppress occurrence of a forming defect such as a crack in a starting material during press forming, and can also suppress occurrence of problems when transferring a starting material during press forming. In the method for manufacturing a press-formed product, a manufacturing intermediate is formed by forming, in a flat-sheet shaped blank sheet, a planned outline portion including an undulating shape which is used for forming an outline of an outer circumferential portion of a press-formed product. Further, the flat shape of the blank sheet is maintained in a region from the planned outline portion toward the center of the manufacturing intermediate, or an intermediate stretch-formed portion having a predetermined intermediate forming height is formed in the manufacturing intermediate in the region. Furthermore, a through-hole is formed by piercing a flat portion at which the flat shape is maintained or a stretch-formed-side top portion of the intermediate stretch-formed portion. In addition, the flat portion after the through-hole is formed therein is formed into a stretch-formed portion of a predetermined height, or the intermediate stretch-formed portion after the through-hole is formed therein is formed into a stretch-formed portion of a predetermined height that is greater than the intermediate forming height.