Foam Molded Article With Alternating Gap Mold
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Solution Overview
Problem
Molded foam products intended for heat insulation have poor strength and heat resistance due to large unfoamed regions, and methods to enhance heat insulation through increased thickness require more materials and higher manufacturing costs, while controlling foaming in thin products leads to surface issues like blisters and crinkles.
Innovation Solution
The method involves injection molding with a mold that alternates between large and small gap sizes to evenly distribute molten resin, using a core-back process to increase cavity volume before resin solidification, and incorporating supercritical fluids or chemical foaming agents to create a foamed layer sandwiched between skin layers, reducing blisters and crinkles while maintaining low material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the molded foam product is increased to enhance heat insulation, then heat insulation performance is improved, but the amounts of materials used and manufacturing cost increase
Solution Approach 1:
The mold includes linear portions with different gap sizes (first linear portions with larger gap sizes and second linear portions with smaller gap sizes) arranged in a specific pattern. This creates local variations in wall thickness, where thicker regions provide enhanced heat insulation where needed, while thinner regions reduce overall material consumption. The differential gap configuration allows optimization of thermal insulation performance without uniformly increasing product thickness and material usage.
2Temperature
If the thickness of the molded foam product is increased to enhance heat insulation, then heat insulation performance is improved, but manufacturing cost increases
Solution Approach 1:
The mold design with alternating large and small gap linear portions creates a structure where heat insulation is enhanced locally in thicker regions without requiring uniform thickness increase across the entire product. This reduces the total amount of resin material needed, thereby lowering material costs and manufacturing expenses while maintaining adequate thermal insulation performance.
3Quantity of substance
If foaming control is attempted in thin molded products to reduce material usage, then material usage is reduced, but surface quality deteriorates with blisters and crinkles
Solution Approach 1:
The mold includes linear portions with different gap sizes arranged alternately, creating regions of varying thickness. The larger gap portions allow better resin flow and foaming control, reducing the likelihood of surface defects such as blisters and crinkles. Meanwhile, the smaller gap portions provide adequate structural support and surface quality. This differential configuration enables effective foaming control in thin-walled regions without compromising overall surface quality.
4Ease of manufacture
If a molded foam product includes large unfoamed regions to simplify manufacturing, then manufacturing is simplified, but strength and heat resistance deteriorate
Solution Approach 1:
The mold design with alternating large and small gap linear portions creates a controlled foaming structure. The larger gap portions facilitate resin flow and can accommodate unfoamed regions, while the smaller gap portions maintain structural integrity and promote foaming. This differential configuration allows the product to have regions with different foam densities, providing both manufacturing simplicity and adequate strength and heat resistance where required.
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
This approach results in molded foam products with excellent heat insulation, high strength, and reduced surface imperfections, achieving cost-effective production with minimal material usage.
Implementation Method 1
injecting a molten resin containing a supercritical fluid or a chemical foaming agent into a cavity
Implementation Method 2
injecting a molten resin containing a supercritical fluid or a chemical foaming agent into a cavity
Implementation Method 3
moving the movable portion to increase the volume of the cavity before the molten resin injected into the cavity completely solidifies
Data Source
AI summary
The present invention provides a method for manufacturing a molded foam product which can reduce or prevent blisters and crinkles on the surface even in the case of manufacturing a molded product designed to have a small thickness, thereby giving a molded foam product having excellent heat insulation while avoiding an increase in the amounts of materials used. The method for manufacturing a molded foam product according to the present invention includes the steps of: injecting, during injection molding, a molten resin containing a supercritical fluid or a chemical foaming agent into a cavity formed in a mold that includes a movable portion; and moving the movable portion to increase the volume of the cavity before the molten resin injected into the cavity completely solidifies, the mold alternately including, in a direction from a resin injection port to the periphery of the cavity, first linear portions each giving a large gap size in the cavity and second linear portions each giving a small gap size in the cavity.