Interior Panel Injection Molding Rib Structure Undercut Elimination
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Solution Overview
Problem
The existing injection molding methods for interior panels with complex concave-convex shapes face challenges in forming undercut portions without using slide dies, which limits design flexibility and can result in molding sinks that degrade the front surface design.
Innovation Solution
A rib structure is integrated into the molding die, featuring a flat bottom portion with projecting ribs and grooves that eliminate undercut spaces on the core die without interfering with die-cutting, allowing for the elimination of slide dies and preventing molding sinks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If slide dies are used to form undercut portions in the core die, then the panel can be molded with complex concave-convex shapes, but the design flexibility is limited and the device complexity increases
Solution Approach 1:
The core die is divided into a movable core die and a fixed core die that remains in the cavity during molding. This segmentation allows the movable core die to form undercut portions without requiring slide mechanisms, as the fixed core die provides stable support and the undercut spaces are naturally eliminated through the molding process geometry.
Solution Approach 2:
Instead of making the core die movable to form undercut portions (conventional approach), the invention makes the cavity die movable and keeps the core die fixed. This inversion allows undercut spaces to be eliminated without slide dies, as the molding process fills resin into the undercut spaces from the cavity side, eliminating the need for complex slide mechanisms in the core die.
2Shape
If undercut spaces on the core die side are plugged back with resin, then the undercut portions are eliminated, but molding sinks occur that degrade the front surface design property
Solution Approach 1:
The invention applies different die configurations to different regions: the cavity die (forming the front surface) is made movable to allow precise control of resin filling, while the core die (forming the back surface with undercut portions) is kept fixed. This local differentiation ensures that undercut spaces are eliminated without creating molding sinks on the front surface, as the movable cavity die can control resin flow and pressure to prevent sink marks.
Solution Approach 2:
The fixed core die is designed in advance to have a configuration that naturally eliminates undercut spaces during the molding process, without requiring post-molding plug-back operations. The die geometry is predetermined to guide resin flow in a way that fills undercut portions before solidification, preventing both the need for slide dies and the occurrence of molding sinks on the front surface.
3Device complexity
If the core die is made movable to eliminate slide dies, then the device complexity is reduced, but the ability to form various shaped portions for design flexibility is compromised
Solution Approach 1:
The invention introduces dynamic elements through the movable cavity die that can assume different positions during the molding process. This mobility allows the cavity die to adapt to various panel designs and form different shaped portions without requiring complex slide mechanisms in the core die. The dynamic positioning of the movable cavity die provides the necessary design flexibility while keeping the core die simple and fixed.
Data Source
AI summary
A resin-made interior panel molded into a thin-plate shape using a cavity die and a core die in which portions which corresponds to undercut portions with respect to the die-cutting direction of the molding die includes on the front surface side of a panel a flat bottom portion having a shape which cancels an entire undercut space on the side of the core-die and a rib structure having a plurality of ribs projecting in the shape of plugging back the undercut space and having a plurality of grooves extending from the bottom portion in the die-cut direction. According to the invention as described above, means which maintain the design shape of the interior panel on the front surface side having the undercut portions is provided without necessity of a slide die in the core die.