Automotive Outer Panel Press Forming to Prevent Character Line Skid Lines
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Solution Overview
Problem
Existing methods for press forming automotive outer panels with character lines often result in skid lines due to tension imbalances, surface distortions, and increased man-hours, as they require specialized tools and suction apparatuses, or fail to form the ridgeline as intended.
Innovation Solution
A method and apparatus using a punch with an elastic body that protrudes beyond the forming surface to contact the metal sheet before the ridgeline, allowing for gentle bending deformation and preventing initial bending folds, thereby reducing skid lines without increasing the number of press forming steps or tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a punch with a sharp ridgeline (small curvature radius) is used to form a character line, then the designability and tension rigidity of the automotive outer panel are improved, but tension imbalance occurs during forming causing the metal sheet to slide and creating skid lines
Solution Approach 1:
The method performs preliminary bending deformation of the metal sheet using the elastic body before the ridgeline contacts the sheet. This pre-forming action gradually deforms the metal sheet to follow the forming surface, preventing tension imbalance and subsequent sliding that would cause skid lines, while still allowing the sharp ridgeline to create the desired character line shape
Solution Approach 2:
The elastic body acts as an intermediary between the punch and the metal sheet. It provides gradual deformation through elastic contact before the rigid ridgeline engages the sheet, mediating the transition from flat sheet to formed shape and preventing direct contact-induced tension imbalance
2Manufacturing precision
If existing techniques such as suction apparatuses or auxiliary cross-sectional shapes are used to prevent skid lines, then surface quality is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The method merges the skid line prevention function into the standard press forming punch by adding an elastic body to the existing ridgeline structure. This combines character line formation and skid line prevention into a single tool and operation, eliminating the need for separate suction apparatuses or auxiliary forming devices
Solution Approach 2:
The elastic body on the punch provides self-service by automatically performing the skid line prevention function during the normal press forming operation. The elastic deformation occurs inherently as the punch contacts the metal sheet, requiring no additional控制系统 or external apparatus
3Manufacturing precision
If multiple press forming steps are used to eliminate skid lines, then surface quality is improved, but productivity decreases due to increased man-hours
Solution Approach 1:
The preliminary bending deformation is performed in the same press forming step that creates the character line, rather than requiring a separate pre-forming step. The elastic body enables this preliminary action to occur simultaneously with the main forming operation, maintaining productivity while preventing skid lines
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 solution effectively prevents skid lines and surface distortions, enabling the formation of automotive outer panels with character lines while maintaining design integrity and reducing man-hours, by ensuring the ridgeline is formed without tension imbalances and surface damage.
Implementation Method 1
an elastic body abutting step of abutting a contact surface portion of the protruding elastic body against the metal sheet by relatively moving the die toward the punch... 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
AI summary
A method for press forming an automotive outer panel includes: providing an elastic body to a punch such that the elastic body abuts against a metal sheet away from a portion corresponding to a character line in the metal sheet; abutting a contact surface portion of the protruding elastic body against the metal sheet; and forming the character line with the ridgeline and the valley line by relatively moving the die toward the punch while abutting the contact surface portion against the metal sheet to deform the elastic body such that the elastic body becomes flush with the punch-side forming surface portion at a bottom dead center of forming. A protrusion amount of the elastic body from the punch-side forming surface portion is set such that the elastic body contacts the metal sheet before the ridgeline contacts the metal sheet to cause the metal sheet to become plastically deformed.