Automotive Trim Protrusion for Resin Flow Control
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Solution Overview
Problem
Synthetic resin moldings used in automotive interiors often develop weld lines due to disturbed resin flow, which affects the orientation of luster agents in metallic colored resins, leading to degraded design effects and aesthetic issues.
Innovation Solution
A synthetic resin molding with a bent portion and a flange having wide and narrow sections, where a gate is positioned at the end of the flange, and a protrusion is formed along the side edge at the boundary between the flange and the molding body to reduce disturbed resin flow, allowing the resin to flow uniformly and maintain luster agent orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flange with wide and narrow portions is continuous with the bent portion at the side edge, then the molding can be mounted onto the counterpart panel with fitting between corresponding surfaces, but the molten resin flows in a disturbed manner creating weld lines on the design surface
Solution Approach 1:
The flange is divided into wide portions and narrow portions that correspond to the contours of the counterpart panel. This segmentation allows the flange to adapt to different mounting surfaces while the protrusion segments the resin flow path, preventing disturbed flow from affecting the design surface.
Solution Approach 2:
A protrusion is introduced as an intermediary structure at the boundary between the flange and the molding body. This protrusion acts as a mediator that redirects the resin flow from the flange, preventing it from interfering with the molding body's resin flow and causing weld lines on the design surface.
2Shape
If the flange has a complex and irregular shape with wide and narrow portions, then fitting between corresponding surfaces is enabled, but weld lines are created on the design surface due to disturbed resin flow from the flange
Solution Approach 1:
The flange is segmented into wide and narrow portions to achieve complex shape for fitting, while the protrusion segments the resin flow path to prevent disturbed flow from reaching the design surface.
Solution Approach 2:
The protrusion serves as an intermediary structure that intercepts and redirects resin flow from the complex-shaped flange, preventing it from creating weld lines on the design surface of the molding body.
3Ease of manufacture
If injection molding is performed with a gate at the end of the flange using metallic colored resin material, then the molding can be formed with mounting functionality, but the orientation of the luster agent is disturbed degrading design effects
Solution Approach 1:
The protrusion acts as an intermediary structure that redirects resin flow, preventing disturbed flow from reaching the molding body where luster agent orientation is critical. This maintains aesthetic appearance while allowing standard injection molding processes.
Solution Approach 2:
The protrusion is positioned to preemptively counteract the disturbed resin flow from the flange before it can reach the molding body. By blocking the harmful flow pattern in advance, the luster agent orientation is preserved without requiring changes to the injection molding process.
4Manufacturing precision
If the protrusion is formed at the boundary portion between the flange and molding body, then interference of resin flow from the flange is reduced, but the device complexity increases
Solution Approach 1:
The protrusion is introduced only at the specific boundary portion between the flange and molding body where resin flow interference occurs. This localized modification improves resin flow control without significantly increasing overall device complexity, as the protrusion is a simple geometric feature integrated into the existing structure.
Data Source
AI summary
A molding method for a synthetic resin molding that includes a molding body, a bent portion, and a flange. The bent portion and the flange are continuous in a longitudinal direction of the side edge. The flange includes a wide portion and a narrow portion. The molding method for the synthetic resin molding includes arranging a gate at a position corresponding to an end of one side of the flange in a longitudinal direction, performing injection molding using a colored resin material containing a luster agent kneaded in the material, and forming a protrusion along the side edge in the longitudinal direction at a back of a boundary portion between the flange and the molding body to reduce interference of flow of the molten resin from the flange toward the molding body during the injection molding.