Hat-Section Press Forming with Twisted Side Walls to Prevent Wrinkles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing press forming methods for hat-shaped cross-section products with web and flange portions, concavely curved in the longitudinal direction, face challenges in preventing fractures and wrinkles, particularly in high-strength steel sheets, due to limitations in material movement and surface accuracy requirements.
Innovation Solution
A press forming method that induces in-plane shear deformation in the twisted side wall portion by preforming a blank with twisted side wall sections, reducing line length differences between web and flange portions, thereby suppressing fractures and wrinkles through controlled torsion and aspect ratio manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If high-strength steel sheets are used to reduce weight, then weight reduction is achieved, but elongation decreases causing fractures and wrinkles
Solution Approach 1:
The invention applies preliminary action by pre-forming the blank into a specific shape with predetermined curvature radius before the main press forming process. This pre-forming creates initial stress distribution and material flow patterns that prevent fractures and wrinkles during subsequent forming of high-strength steel sheets, allowing weight reduction without sacrificing formability
2Ease of manufacture
If conventional press forming is applied to curved parts, then manufacturing simplicity is maintained, but fractures and wrinkles occur
Solution Approach 1:
The invention introduces a pre-forming step that creates specific curvature in the blank before main forming. This preliminary shaping controls material flow and stress distribution, enabling accurate formation of curved parts without fractures or wrinkles while maintaining manufacturing feasibility through standardized press forming equipment
Solution Approach 2:
The invention changes geometric parameters by specifying predetermined curvature radius ranges for the pre-formed blank. By optimizing these curvature parameters, the material flow and stress distribution are controlled to prevent defects, achieving high surface accuracy while maintaining ease of manufacture through parameter optimization rather than complex process changes
3Reliability
If the blank is pre-formed with specific curvature, then material flow is controlled reducing fractures, but additional processing steps are required
Solution Approach 1:
The pre-forming step creates specific curvature in the blank to control material flow during main forming, effectively suppressing fractures and wrinkles. Although this adds a processing step, the pre-forming can be integrated with existing press forming equipment, and the improved reliability prevents costly defects and rework, justifying the additional process complexity
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 suppresses fractures and wrinkles in press-formed products, enabling the formation of hat-shaped cross-section products with improved surface accuracy and reduced deformation issues, suitable for high-strength steel sheets.
Implementation Method 1
A press forming method that induces in-plane shear deformation in the twisted side wall portion by preforming a blank with twisted side wall sections
Data Source
Figure 1(a-1)~1(b)
Figure 2(a)~2(c)
Figure 3
AI summary
A press forming method according to the present invention is to form a press-formed product 1 having a hat-shaped cross section and including a web portion 3, a side wall portion 5, a flange portion 7, and a concave curved portion 11 concavely curved in a height direction along a longitudinal direction in side view. The press forming method includes: a first forming process of press-forming a preformed part 21 in which a portion 23 corresponding to web, and a portion 25 corresponding to side wall including a twisted side wall portion 25a of a twisted shape along the longitudinal direction, are formed, the preformed part 21 including a portion 31 corresponding to concave curve; and a second forming process of press-forming the preformed part 21 into the press-formed product 1 having a target shape. The twisted side wall portion 25a at the first forming process is twisted such that an angle between the twisted side wall portion 25a and the portion 23 corresponding to web is smaller on an end portion side than at a longitudinal center of the portion 31 corresponding to concave curve.