Foam-Molded Skin Layer Control for Pock Mark Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Foam injection-molded products for automobile parts are prone to appearance defects such as pock marks and swirl marks due to bubble rupture and resin flow, which affect their surface quality.
Innovation Solution
The foam-molded product is designed with a maximum bubble diameter of 0.90 mm or less and a skin layer thickness of 0.3 mm to 0.7 mm, achieved through controlled foaming and a core-back process to maintain a ±0.2 mm thickness tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If foam injection molding is performed to achieve lightweight and thin automobile parts, then weight reduction and thinning are accomplished, but appearance defects such as pock marks and swirl marks occur on the surface
Solution Approach 1:
The patent applies parameter changes by precisely controlling the bubble diameter (maximum 0.90 mm or less) and skin layer thickness (0.3 mm to 0.7 mm) through modified injection molding parameters. This resolves the contradiction by adjusting process parameters to achieve both lightweight thin-walled parts and surface free from appearance defects
Solution Approach 2:
The patent employs preliminary action by forming a controlled skin layer of specific thickness before the foaming process completes. This preliminary skin layer formation prevents subsequent bubble rupture and defect generation, allowing lightweight thin-walled parts to be produced without surface defects
2Length of moving object
If the skin layer thickness is reduced to make the product thinner, then the product can be thinner and lighter, but bubbles may rupture through the skin layer causing pock marks
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal parameter range for skin layer thickness (0.3 mm to 0.7 mm) that is thin enough to meet lightweight requirements but thick enough to prevent bubble rupture. This parameter optimization allows thin-walled parts without pock marks
3Quantity of substance
If the foaming process is intensified to reduce material usage and achieve thinner walls, then weight reduction is improved, but bubble size increases leading to larger pock marks and swirl marks
Solution Approach 1:
The patent applies parameter changes by controlling the maximum bubble diameter to 0.90 mm or less through optimized foaming parameters. This prevents excessive bubble growth that would cause swirl marks while still achieving reduced material usage and thin-walled structures
Solution Approach 2:
The patent employs feedback control by monitoring and controlling bubble size parameters during the foaming process. This ensures bubbles remain within the critical diameter threshold (0.90 mm or less) to prevent swirl mark formation while achieving material efficiency
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 effectively suppresses appearance defects, ensuring a high-quality surface finish by maintaining uniform bubble sizes and controlled thickness, suitable for automobile interior and exterior parts.
Implementation Method 1
a foam layer, wherein a maximum diameter of bubbles in the foam layer is 0.90 mm or less
Data Source
AI summary
A foam-molded product including a foam layer, and a skin layer covering the foam layer, in which the maximum diameter of bubbles in the foam layer is 0.90 mm or less; and a method for manufacturing a foam-molded product and a method for suppressing an appearance defect of a foam-molded product, including an injection process and a foaming process, wherein the foam-molded product after molding includes a foam layer and a skin layer covering the foam layer, the skin layer having an average thickness of from 0.3 mm to 0.7 mm, and wherein expanding of the volume of the cavity includes performing a core-back process of the mold such that a thickness of the foam-molded product after molding is within ±0.2 mm of a predetermined target thickness.