Press Forming of U-Shaped Parts With Reduced Side-Wall Creases
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Solution Overview
Problem
The existing press forming methods for automotive parts with U-shaped or hat-shaped cross sections often result in residual bending creases, which hinder resistance spot welding due to uneven surfaces, and require additional steps for straightening, decreasing productivity.
Innovation Solution
A press forming method that uses a punch with sloped surface portions and a die with flange unbending portions to unbend flange portions of a pre-unbending press formed part, reducing bending crease size without the need for a special straightening device by controlling the position and angle of the punch side ridge line portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If flange portions are unbent to form high forming height side wall portions, then the forming height is improved, but bending creases are generated on the side wall portions
Solution Approach 1:
The punch side ridge line portion is positioned to contact the inner surface side of the side wall portion during the flange unbending process. This preliminary action occurs during the main forming operation, allowing the ridge line to suppress bending crease generation as the flange is unbent, without requiring a separate straightening step
Solution Approach 2:
The punch side ridge line portion acts as an intermediary element between the punch and the side wall portion. It mediates the unbending process by providing controlled contact that suppresses bending creases while allowing the flange to be unbent to the desired forming height
2Volume of moving object
If bending creases are generated on side wall portions, then the forming height is achieved, but additional straightening steps are required
Solution Approach 1:
The function of suppressing bending creases is merged into the main flange unbending operation through the punch side ridge line portion. This combines two functions (unbending and crease suppression) into a single integrated process, eliminating the need for separate straightening steps and improving productivity
Solution Approach 2:
The punch side ridge line portion enables the forming process to self-correct bending creases during the unbending operation itself. The system uses its own forming mechanism to prevent the defect rather than requiring external intervention or additional processing steps
3Ease of manufacture
If flange portions are unbent in conventional press forming, then side wall portions are formed, but bending creases hinder resistance spot welding
Solution Approach 1:
The punch side ridge line portion performs preliminary suppression of bending creases during the flange unbending process. This preliminary action ensures that the side wall portions are formed with sufficient flatness for resistance spot welding before the welding operation occurs, eliminating the need for separate straightening steps
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 reduces bending crease size in side wall portions, enhancing the flatness of the surface for welding and improving productivity by eliminating the need for an additional straightening step.
Implementation Method 1
unbending the flange portions by the flange unbending portions while the punch side ridge line portions are brought into contact with inner surface sides of the side wall portions
Data Source
AI summary
A press forming method for a press formed part includes: placing a pre-unbending press formed part on a punch including a top forming surface portion configured to form a top portion of the press formed part, and side-wall forming surface portions configured to form side wall portions, each of the side-wall forming surface portions including a punch side first sloped surface portion, and a punch side second sloped surface portion; relatively moving a die toward the punch, the die including flange unbending portions; and unbending flange portions by the flange unbending portions while punch side ridge line portions are brought into contact with inner surface sides of the side wall portions to form the side wall portions of the press formed part.