Injection Foaming Mold Capacity Change Shape
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Solution Overview
Problem
Conventional foam molding methods face issues with strength reduction and economic inefficiency due to limited foaming ratio enhancement, and partial core back methods result in surface degradation and swelling due to uneven pressure distribution and shrinkage.
Innovation Solution
An injection foaming mold with a fixed core and movable core, where the die capacity changes smoothly and continuously from the fixed core to the movable core, allowing for controlled foaming and pressure reduction to produce foamed plastic products with varying cell densities, preventing surface degradation and swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the foaming diameter is increased to enhance the foaming ratio, then the weight reduction is improved, but the partition walls between foam cells become thin and the strength of the molding product decreases remarkably
Solution Approach 1:
The patent applies local quality by differentiating the treatment between two regions: the first region undergoes core back to achieve high foaming ratio and weight reduction, while the second region maintains normal pressure to preserve strength and avoid excessive swelling. This spatial differentiation of processing conditions allows each region to optimize its properties locally.
Solution Approach 2:
The molding die is segmented into two distinct regions: a first region subjected to core back and a second region not subjected to core back. This segmentation allows independent control of foaming conditions in different areas, enabling the product to simultaneously achieve weight reduction in some areas while maintaining structural integrity in others.
2Loss of substance
If the core back is performed partially to enhance foaming ratio in specific portions, then the weight reduction is improved, but a shrinkage ratio varies at the boundary causing step difference and deformation
Solution Approach 1:
The patent implements local quality by creating a transition region between the first and second regions where the die capacity changes gradually. This gradual change in capacity at the boundary prevents abrupt shifts in foaming conditions, thereby eliminating step differences and deformation while maintaining the weight reduction benefits of partial core back.
3Loss of substance
If the core back is performed to enhance the foaming ratio, then the weight reduction is improved, but a portion not subjected to core back is swollen when taken out of the die
Solution Approach 1:
The patent applies local quality by restricting core back to only the first region while leaving the second region untreated. This selective application prevents the swelling problem in the second region because it never experiences the pressure reduction that causes excessive foaming and subsequent swelling, while the first region still achieves weight reduction through controlled core back.
4Quantity of substance
If the foamable resin is injected to produce a foamed plastic product with large foaming ratio, then the economic effect such as reduction in materials is improved, but the partition walls between foam cells become thin to decrease the strength remarkably
Solution Approach 1:
The patent applies local quality by differentiating the foaming treatment between two regions: the first region undergoes core back to achieve high foaming ratio and material reduction, while the second region maintains normal pressure to preserve strength. This allows the product to have reduced material quantity in non-critical areas while maintaining adequate strength in load-bearing areas.
Solution Approach 2:
The patent segments the molding die into a first region for high foaming ratio and a second region for strength preservation. This segmentation enables the product to simultaneously achieve material reduction and adequate strength by assigning different functional requirements to different spatial zones.
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 enhances foaming ratio without compromising strength, reduces material usage, and minimizes surface distortions and swelling, resulting in improved component precision and appearance.
Implementation Method 1
under a state in which the foamable resin is uncured, a capacity in the die is enlarged and a pressure applied to the foamable resin in the uncured state is reduced to accelerate foaming in the die
Implementation Method 2
a foamable resin containing a foaming agent is injected into a die in a molten state
Data Source
AI summary
Provided is an injection foaming mold capable of preventing, when formed resin molding is performed by a partial core back, degradation of an outer appearance and component precision, and occurrence of swelling when a portion that is not subjected to the core back is taken out of a die. The injection foaming mold includes at least: a fixed core that avoids moving; and a movable core that performs the core back. The injection foaming mold further includes a capacity change shape portion, which is formed in a region in which a capacity in the die is changed smoothly and continuously from the fixed core side to the movable core side, the capacity change shape portion being formed at a boundary between the fixed core and the movable core.