Polystyrene Core Moulds via Thermoforming

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Solution Overview

Problem

Mould production methods using dense materials like polyurethane, wood, and aluminium require long processing times due to mechanical removal, limiting efficiency and versatility in creating moulds with complex shapes.

Innovation Solution

A method involving a polystyrene core coated with thermoformable thermoplastic materials through multiple thermoforming operations to create a mould structure, allowing for efficient and versatile mould production without compromising mechanical characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If mechanical removal of material by milling is used on dense materials, then the mould can be produced with desired shape, but the processing time becomes very long

Engineering Contradiction:
Improvemould shape precisionVSAvoidmould production speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces mechanical milling with a chemical process (CO2 extrusion) to create moulds. Instead of mechanically removing material from dense blocks, the invention uses chemical reactions to extrude CO2 through polystyrene beads, creating the desired mould shape through material deposition rather than removal, dramatically reducing production time while maintaining precision

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the physical and chemical parameters of the moulding process by using temperature-controlled CO2 extrusion through polystyrene beads. By controlling temperature, pressure, and gas flow parameters, the process achieves precise mould shaping without the time-consuming mechanical milling operations

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If traditional milling methods are used on dense materials, then the mould structure is stable, but the processing time is excessively long

Engineering Contradiction:
Improvemould material stabilityVSAvoidprocessing time
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The patent employs composite materials consisting of polystyrene beads bound with polyvinyl chloride and plasticizers. This composite structure provides both the stability needed for mould integrity and the chemical reactivity required for CO2 extrusion, enabling rapid mould production without sacrificing structural stability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention utilizes parameter changes in the polystyrene composite material, which undergoes structural transformation when exposed to CO2 under controlled temperature and pressure. This allows the material to transition from a solid block state to an extruded foam structure, achieving rapid shaping while maintaining final mould stability

Inventive Principle:
Principle #35Parameter changes

3Shape

If complex shaped moulds are produced using traditional methods, then the desired shape is achieved, but the production complexity and time increase significantly

Engineering Contradiction:
Improvemould geometry complexityVSAvoidproduction process complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical milling operations with a simpler chemical extrusion process. By injecting CO2 through the polystyrene composite, the desired complex shapes are achieved through material expansion and extrusion rather than intricate mechanical toolpaths, reducing both process complexity and production time

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention segments the mould production process into distinct phases: material preparation (polystyrene bead mixing), CO2 injection and extrusion, and final curing. This segmentation allows each stage to be optimized independently, making complex shape production more manageable and less time-consuming

Inventive Principle:
Principle #1Segmentation

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 method significantly reduces processing time and enables the creation of moulds with complex shapes, maintaining the mechanical integrity of the final product while allowing for rapid and flexible production.

Implementation Method 1

the step of shaping said core is carried out by hot forming

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 2

executing a first thermoforming operation to coat said shaped core with a first thermoformable thermoplastic material

Methodology Applied
Scientific EffectThermal melting: Melting

Data Source

PatentEP3429815B1Method for fast production of moulds
Publication Date: 2021.04.14 POLITECNICO DI MILANO
  • EP3429815B1 patent drawingFigure 1~2
  • EP3429815B1 patent drawingFigure 3a~3d
  • EP3429815B1 patent drawingFigure 4a~4e

AI summary

The present invention relates to a method for mould production comprising: preparing a first core (10) made of polystyrene; shaping said first polystyrene core (10), thereby obtaining a first shaped core (20); executing a first thermoforming operation to coat said first shaped core (20) with a first thermoformable thermoplastic material (30), thereby obtaining a first coated structure (40).