Complex Hollow Models from Low Modulus Material

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Solution Overview

Problem

Existing methods for creating customized complex hollow models from low modulus materials, such as those used for medical implant simulations, are costly and difficult to produce with high accuracy and efficiency.

Innovation Solution

A method involving additive manufacturing to form a precursory structure with inner and outer shells, using phase change material for support and venting, followed by injection and curing of a flexible polymer, and subsequent removal of the shells to create a hollow article, facilitating efficient and accurate production of complex geometries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional methods are used to create customized complex hollow models from low modulus materials, then the models can be produced, but the process is costly and difficult with low efficiency

Engineering Contradiction:

Improveproduction efficiencyVSAvoidmanufacturing difficulty

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The manufacturing process is divided into distinct sequential stages: (1) creating a mold structure with inner and outer shells, (2) injecting liquid polymer into the cavity, (3) curing the polymer, and (4) removing the mold structure. This segmentation allows each stage to be optimized independently, improving overall efficiency and reducing manufacturing difficulty.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mold structure is prepared in advance with properly sized cavities and channels before polymer injection. The inner and outer shells are pre-formed with precise geometries that will define the final hollow model. This preliminary preparation eliminates the need for complex real-time adjustments during polymer curing, significantly reducing manufacturing difficulty and time.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If traditional methods are used to create customized complex hollow models, then the models can be produced, but with low dimensional precision and thickness uniformity

Engineering Contradiction:

Improvedimensional precisionVSAvoidproduction efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The method uses a mold structure that directly copies the desired final geometry into the liquid polymer. The inner and outer shells of the mold are precisely formed to match the target dimensions, and the liquid polymer faithfully reproduces this geometry upon curing. This copying approach ensures high dimensional precision and thickness uniformity without requiring complex post-processing adjustments.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The polymer is in a liquid state during injection, allowing it to flow and conform precisely to the mold cavity geometry. Upon curing, the polymer transitions from liquid to solid, locking in the precise dimensional parameters defined by the mold. This parameter change (liquid to solid) enables high precision manufacturing while maintaining production efficiency.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If low modulus materials are used for medical implant simulations, then the models provide accurate tissue mechanical properties, but the materials are difficult to form into complex geometries

Engineering Contradiction:

Improvematerial accuracyVSAvoidformability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The liquid polymer is injected under pressure into the mold cavity, using hydraulic principles to force the material into complex geometries. The liquid state allows the polymer to flow around intricate features and fill cavities completely, achieving complex formability while maintaining material accuracy. The pressure-driven injection ensures complete filling without air pockets or incomplete curing.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 improves the efficiency and accuracy of producing complex hollow models, reducing costs and enhancing dimensional precision and thickness uniformity compared to previous methods.

Implementation Method 1

a first volume (34) formed from a phase change material filling an inner cavity (36) defined by an inner surface (26) of the inner shell (22), a second volume (38) formed from the phase change material filling an outer cavity (40) defined between the inner (22) and outer (24) shells

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

injecting uncured liquid flexible polymer material into the outer cavity, curing and solidifying the uncured liquid flexible polymer to provide cured and solidified flexible polymer material

Methodology Applied

Scientific EffectCuring: Photopolymerisation

Data Source

PatentUS11491740B2Method for forming complex hollow models from low modulus material

Publication Date: 2022.11.08 3D SYSTEMS INC

AI summary

A method is provided for manufacturing a complex hollow article from a flexible polymer material. The method includes using an additive manufacturing system to form a precursory structure that is formed from a build material and phase change material, melting and removing the phase change material, injecting uncured liquid flexible polymer material into a cavity defined by the build material, curing and solidifying the flexible polymer material, and cracking and removing the build material from the flexible polymer material to provide the hollow article.