Hat-Section Press Forming for Flange Angle Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing press forming methods for hat-shaped cross-section products struggle to maintain high accuracy of the flange angle due to springback, especially when using high-strength steel sheets, leading to reduced joinability with other parts.
Innovation Solution
A two-step press forming method is employed, where a preformed part with side wall portions having an outwardly projecting chevron shape is first formed, and then reshaped into the target form. The angle of the side wall portion adjacent to the top is set to decrease towards the end portion from the center in the longitudinal direction, and the height from the top to the bent portion is increased towards the end portion, to suppress springback and maintain flange angle accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-strength steel sheet is used for press-forming, then the strength of the press-formed product is improved, but the angle of the flange portion changes due to springback and manufacturing precision deteriorates
Solution Approach 1:
The patent applies preliminary action by forming a preformed part with predetermined side wall shapes before final press-forming. The side walls are formed with specific angles (first side wall: 45-60 degrees, second side wall: 15-30 degrees) in advance to compensate for springback that will occur during final forming, ensuring accurate flange angles in the finished product.
Solution Approach 2:
The patent applies local quality by giving different angle characteristics to different parts of the side walls. The first side wall has a larger angle (45-60 degrees) while the second side wall has a smaller angle (15-30 degrees), allowing each region to be optimized for its specific function in controlling springback and achieving the target flange angle.
2Productivity
If a conventional one-step press-forming method is used, then productivity is improved, but the accuracy of the flange angle deteriorates due to springback
Solution Approach 1:
The patent applies segmentation by dividing the press-forming process into two distinct steps: first forming a preformed part with specific side wall angles, then performing final press-forming to achieve the target shape. This segmentation allows each step to be optimized for its specific purpose, with the first step controlling springback and the second step achieving final geometry.
3Ease of manufacture
If the side wall angle is uniform along the longitudinal direction, then ease of manufacture is improved, but the accuracy of the flange angle at end portions deteriorates due to wall curl
Solution Approach 1:
The patent applies local quality by varying the side wall angles along the longitudinal direction. The first side wall maintains a larger angle (45-60 degrees) while the second side wall uses a smaller angle (15-30 degrees), with specific configurations at end portions to counteract wall curl effects and ensure accurate flange angles throughout the entire length of the product.
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 suppresses the wall curl of the side wall portion due to springback, reducing the angle change of the flange portion over the entire length, thereby enabling high-accuracy press forming of the flange angle.
Implementation Method 1
press-forming a preformed part... press-forming the preformed part into the target shape
Implementation Method 2
the angle of the flange portion is changed due to springback after press-forming
Data Source
AI summary
A press forming method includes: a first forming step of press-forming a preformed part including: a top portion and flange portions having same shapes as a top portion and a flange portions in a target shape of a press-formed product; and side wall portions having projecting chevron shape in a cross-section in a press-forming direction as compared with side wall portions; and a second forming step of press-forming the preformed part into the target shape. Each side wall portions includes: a side wall portion adjacent to top connecting to the top portion; a side wall portion adjacent to flange connecting to the flange; and a bent portion between the side wall portion adjacent to top and the side wall portion adjacent to flange. An angle on an acute side formed by the side wall portion adjacent to top and a horizontal plane decreases toward an end portion from a center.