Molding Die Recess Guide for Undercut Scratch Prevention
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Solution Overview
Problem
Conventional molding dies for synthetic plastic bumpers with undercuts often cause scratches during demolding due to friction between the undercut and demolding core, especially when the bumper's rigidity varies, leading to visible scratches when attached to vehicles.
Innovation Solution
A molding die design featuring a recessed portion on the die body that gradually reduces in depth and a projecting portion on the undercut, which restricts movement perpendicular to the demolding core's direction, preventing sliding and potential scratches, while maintaining the bumper's rigidity and avoiding unnecessary weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bumper has high rigidity at the lower edge part, then the bumper maintains structural strength, but the lower part deforms less during demolding causing the undercut to scratch against the demolding core
Solution Approach 1:
A guide groove is introduced as an intermediary element between the undercut and the demolding core. The guide groove restricts the movement direction of the undercut during demolding, preventing it from scratching against the demolding core while allowing the high rigidity of the bumper to be maintained
Solution Approach 2:
The guide groove changes the movement parameters of the undercut by constraining it to move only in the direction of the groove. This parameter change allows the undercut to separate from the die body without deviating perpendicular to the demolding direction, thereby preventing scratches
2Strength
If multiple ribs are formed on the rear surface of the undercut to enhance rigidity, then the undercut rigidity is improved, but the weight of the bumper increases
Solution Approach 1:
The invention extracts the rigidity enhancement function from the traditional rib structure and relocates it to the guide groove structure on the die body. This allows the undercut to maintain sufficient rigidity through the guidance constraint rather than through added material, thereby avoiding weight increase
Solution Approach 2:
Instead of adding ribs to the entire rear surface of the undercut, the guide groove provides localized guidance only where needed for scratch prevention. This local quality approach enhances rigidity control without unnecessarily increasing the overall weight of the bumper
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 scratches on the undercut during demolding, enhancing the molding quality and ensuring that the bumper remains intact, even when attached to a vehicle, by restricting movement perpendicular to the demolding core's direction, thus maintaining the bumper's integrity and appearance.
Implementation Method 1
the demolding core elastically deforms the molded article such that the undercut moves away from the die body
Data Source
AI summary
Provided is a molding die including a die body for molding a molded article, which has an undercut, and a demolding core movable to approach and separate from the die body. When the demolding core is separated from the die body, the demolding core elastically deforms the molded article such that the undercut separates from the die body and makes it possible to remove the molded article from the die body. The die body includes a recess where the depth gradually reduces along the direction in which the demolding core separates from the die body. During molding of the molded article, a projection is formed on the undercut in accordance with the shape of the recess. During removal of the molded article, the engagement between the projection and the recess regulates the movement of the molded article in a direction intersecting the movement direction of the demolding core.