Outer Panel Press Forming With Elastic Pre-Bending for Sharp Character Lines
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Solution Overview
Problem
Existing press forming techniques for automotive outer panels with sharp character lines suffer from skid lines due to tension imbalances, leading to surface distortions and increased man-hours, and require additional equipment like suction apparatuses or multiple tool changes.
Innovation Solution
A method and apparatus using a punch with an elastic body that contacts the metal sheet before the ridgeline, forming a character line by gradually bending the metal sheet to prevent skid lines, utilizing a movable device to support the elastic body and adjust its contact position and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a punch with a sharp ridgeline (small curvature radius) is used to form a sharp character line, then the designability of the automotive outer panel is improved, but tension imbalance occurs in the metal sheet causing skid lines and surface distortions
Solution Approach 1:
The elastic body is positioned to contact the metal sheet before the ridgeline, performing preliminary bending action on the metal sheet in the high-tension region. This preliminary deformation prepares the metal sheet for subsequent forming by the ridgeline, preventing tension imbalance and skid line formation while enabling sharp character line formation
Solution Approach 2:
The elastic body acts as an intermediary element between the punch and the metal sheet. It mediates the forming process by first contacting the metal sheet, gradually bending it, and then allowing the ridgeline to form the character line. This intermediary action prevents direct contact between the sharp ridgeline and the metal sheet, eliminating skid lines while maintaining character line sharpness
2Manufacturing precision
If existing techniques (suction apparatus, multiple tool changes, pre-forming processes) are used to prevent skid lines, then surface quality is improved, but device complexity or manufacturing time increases
Solution Approach 1:
The elastic body is integrated into the punch structure itself, merging the skid line prevention function with the character line forming function. This eliminates the need for separate suction apparatus, multiple tool changes, or additional pre-forming equipment, reducing device complexity while maintaining surface quality
Solution Approach 2:
The punch with the elastic body performs multiple functions: it forms the sharp character line using the ridgeline and simultaneously prevents skid lines using the elastic body. This multi-functional design eliminates the need for separate dedicated equipment for each function, reducing overall device complexity
3Manufacturing precision
If existing techniques (suction apparatus, multiple tool changes, pre-forming processes) are used to prevent skid lines, then surface quality is improved, but manufacturing time increases
Solution Approach 1:
The elastic body performs preliminary bending action during the same press forming cycle that forms the character line. This eliminates the need for separate pre-forming steps or post-forming corrections, reducing manufacturing time while maintaining surface quality
Solution Approach 2:
The elastic body continuously contacts the metal sheet throughout the forming process, providing ongoing prevention of skid lines as the metal sheet is deformed. This continuous action occurs within the single press forming cycle, eliminating the need for multiple discrete steps and reducing total manufacturing time
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
Prevents skid lines and surface distortions while maintaining the desired character line shape without increasing man-hours, ensuring a high-quality finish.
Implementation Method 1
a character line forming step of forming the character line with the ridgeline and the valley line by further relatively moving the die toward the punch while abutting the contact surface portion of the protruding elastic body against the metal sheet to deform the elastic body
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3(a)~3(d)
AI summary
A method for press forming an automotive outer panel according to the present invention uses a punch 3, a die 5, and a blank holder 7 to press form a metal sheet 51 into an automotive outer panel 61 having a character line 63 and panel surface portions 65a and 63b, the method including a step of providing the punch 3 with an elastic body 9 caused to protrude toward the die 5 beyond a punch-side forming surface portion 3c and making the elastic body 9 in contact with the metal sheet 51 and a step of performing press forming while making the elastic body 9 in contact with the metal sheet 51 and forming the character line at a bottom dead center of forming . A protrusion amount of the elastic body 9 from the punch-side forming surface portion 3c is set such that the elastic body 9 contacts the metal sheet 51 before a ridgeline 3a of the punch 3 contacts the metal sheet 51 to cause the metal sheet 51 to become plastically deformed.