Variable Density Hollow Thermoplastic Article

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Solution Overview

Problem

Existing methods for manufacturing lightweight hollow bodies with foamed layers in the automotive industry face limitations, including uniform foamed layer ratios that lead to structural deficiencies at specific locations like mounting tabs and bellows, and the inability to selectively locate foamed material for improved acoustic or heat transfer properties.

Innovation Solution

A thermoplastic article with a hollow body comprising a first layer and a foamed second layer, where the ratio of the first layer to the foamed second layer varies along the length, allowing for localized adjustments in density and material distribution through a process involving extrusion of a parison with varying material proportions and subsequent blow molding to form a blow molded article with non-uniform wall structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a uniform ratio of foamed layer to skin layer is used throughout the part, then the manufacturing process is simple and cost-effective, but structural deficiencies occur at locations such as mounting tabs, bellows, and mounting cuffs

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidstructural strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent applies local quality by varying the ratio of foamed layer to skin layer at different locations along the article. Specifically, the skin layer thickness is increased at discrete locations such as mounting tabs, bellows, and mounting cuffs where structural strength is required, while maintaining a lighter foamed layer ratio in other areas. This allows the article to have optimized structural properties at critical locations while preserving the overall lightweight characteristics and cost-effectiveness of the foamed structure.

Inventive Principle:

Principle #3Local quality

2Weight of moving object

If foamed plastic is used throughout the article, then the article achieves lightweight properties, but the ability to selectively locate material for improved acoustic or heat transfer properties is lost

Engineering Contradiction:

Improvearticle weightVSAvoidselective material location capability

Core Design Contradiction:

Weight of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent enables selective material location by controlling the extrusion process to vary the skin layer thickness and foamed layer ratio at different locations along the article. This allows strategic placement of denser skin material in areas requiring enhanced acoustic insulation or heat transfer properties, while maintaining lightweight foamed structure in areas where these properties are less critical. The process provides adaptability in material distribution without sacrificing overall weight reduction.

Inventive Principle:

Principle #3Local quality

3Strength

If additional solid material is introduced at specific locations to improve structural strength, then structural deficiencies are addressed, but the cost and manufacturing complexity increase

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent addresses structural deficiencies cost-effectively by utilizing parameter changes in the extrusion process. By adjusting the skin layer thickness and foamed layer ratio through controlled material flow rates and die design, additional solid material is introduced only at specific locations requiring enhanced strength. This avoids the need for separate manufacturing steps or additional components, thereby improving structural strength while minimizing increases in manufacturing cost and complexity.

Inventive Principle:

Principle #35Parameter changes

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 enables cost-effective introduction of additional solid material at specific locations, reducing foamed material ratios where needed, enhancing structural strength and durability while maintaining lightweight properties, and improving acoustic and thermal insulation.

Implementation Method 1

air is injected into the parison to expand the parison to fill the mold

Methodology Applied

Scientific EffectGas expansion: Pressure Increase

Implementation Method 2

a foamed second layer, the first layer and foamed second layer defines a wall structure, the foamed second layer having a lighter density relative to the first layer

Methodology Applied

Scientific EffectFoaming: Foam

Data Source

PatentUS9038672B2Hollow article of variable wall structure density

Publication Date: 2015.05.26 ABC TECH INC

AI summary

A molded thermoplastic article including a hollow body is provided, the article comprising a first layer, and a foamed second layer, the first layer and foamed second layer defining a wall structure, the foamed second layer having a lighter density relative to the first layer. In the wall structure, the ratio of the first layer to foamed second layer varies along the length of the article.