Thermoplastic Vessel Manufacturing with Cooling Liquid Rigidity

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Solution Overview

Problem

Existing methods for manufacturing pressure-resistant and leak-tight vessels using thermoplastic materials face challenges such as incompatibility between thermoplastic and thermoset materials, difficulty in recycling, and the need for additional layers that compromise mechanical strength and gas/liquid tightness, especially in smaller vessels like fire extinguishers.

Innovation Solution

A method involving a removable external mandrel for forming a thermoplastic internal wall, followed by reinforcement with additional thermoplastic material through winding and heat consolidation, using a cooling liquid to maintain the internal wall's rigidity and integrity during the process, resulting in a single-layer thermoplastic vessel with enhanced mechanical strength and gas/liquid tightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal vessels are used for high pressure storage, then strength and pressure resistance are improved, but weight increases and corrosion resistance deteriorates

Engineering Contradiction:
Improvepressure resistanceVSAvoidvessel weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent applies composite materials by combining thermoplastic synthetic material (for corrosion resistance and lightweight properties) with thermoset material or reinforcement layers (for strength and pressure resistance). This creates a multi-layer composite structure that achieves both lightweight and high strength requirements, resolving the contradiction between weight and pressure resistance.

Inventive Principle:
Principle #40Composite materials

2Strength

If metal vessels are used, then strength is improved, but corrosion resistance deteriorates due to rust formation

Engineering Contradiction:
Improvestructural strengthVSAvoidcorrosion and rust
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent uses composite materials where the thermoplastic synthetic material layer provides corrosion resistance by isolating the vessel interior from aggressive substances, while the thermoset material or reinforcement layers provide structural strength. This composite approach simultaneously achieves both corrosion resistance and structural integrity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by using different materials for different functional requirements: the inner layer uses thermoplastic synthetic material specifically for corrosion resistance where it contacts the stored substance, while outer layers use thermoset material for strength where structural support is needed.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If multi-layer construction is used with thermoplastic and thermoset materials, then corrosion resistance is improved, but compatibility and manufacturing complexity worsen

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidmanufacturing complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by first forming the thermoplastic synthetic material layer as an inner liner before adding the thermoset material or reinforcement layers. This sequential approach simplifies manufacturing by establishing the corrosion-resistant base layer first, then building strength layers upon it, avoiding the complexity of simultaneously coordinating multiple material applications.

Inventive Principle:
Principle #10Preliminary action

4Ease of manufacture

If air escape holes are provided in metal outer layer, then blow-molding is enabled, but mechanical strength deteriorates

Engineering Contradiction:
ImprovemoldabilityVSAvoidouter layer strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent applies inversion by reversing the traditional approach: instead of providing air escape holes in the outer metal layer during blow-molding, the invention forms the thermoplastic inner layer first using blow-molding techniques, then adds the thermoset material or reinforcement layers subsequently. This eliminates the need for air escape holes in the final structure, preserving mechanical strength while still enabling the blow-molding process for the inner layer.

Inventive Principle:
Principle #13The other way round (Inversion)

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 method produces vessels that are lightweight, cost-effective, and resistant to corrosion and high temperatures, maintaining mechanical strength and gas/liquid tightness, while avoiding the limitations of multi-layered constructions and the risks associated with metal vessels.

Implementation Method 1

filling of the thermoplastic internal wall with a cooling liquid; consolidation of the reinforced thermoplastic material by heat; removal of the cooling liquid

Methodology Applied
Scientific EffectThermal cooling: Cooling

Implementation Method 2

consolidation of the reinforced thermoplastic material by heat

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP2732197B1Method for producing a pressure-resistant and/or leak-tight vessel for holding a gas and/or liquid
Publication Date: 2020.11.11 COVESS
  • EP2732197B1 patent drawingFigure 1
  • EP2732197B1 patent drawingFigure 2~3
  • EP2732197B1 patent drawingFigure 4~5

AI summary

The present invention relates to a method for the manufacture of pressure-resistant gas and/or liquid tight containers made from thermoplastic materials. To this end the method comprises the following steps : providing a removable external mandrel around a neckpiece, followed by providing at the inside of such mandrel a thermoplastic material for the manufacture of a thermoplastic internal wall. Hereupon the external mandrel is removed and the thermoplastic internal wall is filled with a cooling liquid. Hereupon additional thermoplastic material is provided to the external side of the thermoplastic wall and is consolidated either during the provision hereof, or thereafter or both. Hereupon the cooling liquid is removed and the container is ready for being used.