Rotating Nozzle Shear Heating for Polymer Extrusion

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Solution Overview

Problem

The speed of polymer deposition in additive manufacturing is limited by the nozzle's ability to conduct heat and melt the polymer, with local degradation occurring when the polymer contacts the nozzle wall, restricting the temperature and thus the extrusion rate.

Innovation Solution

A rotatable nozzle structure is used to introduce shear stress within the polymer, generating heat and melting it as it passes through, enhancing the heating and melting process, which can increase the extrusion rate by viscous dissipation and internal friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the nozzle temperature is increased to melt polymer faster, then the extrusion rate increases, but local degradation occurs where polymer contacts the nozzle wall

Engineering Contradiction:

Improveextrusion rateVSAvoidlocal degradation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The nozzle is made rotatable rather than stationary, allowing dynamic motion during extrusion. This rotation creates varying contact between polymer and nozzle wall, preventing localized overheating and degradation while maintaining efficient melting through controlled shear heating.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The rotation of the nozzle introduces mechanical motion that generates shear stress within the polymer, converting mechanical energy to thermal energy through viscous dissipation. This shear heating efficiently melts the polymer without requiring excessive nozzle wall temperature that would cause degradation.

Inventive Principle:

Principle #18Mechanical vibration

2Reliability

If the nozzle wall temperature is limited to prevent degradation, then polymer degradation is reduced, but the speed of polymer deposition decreases

Engineering Contradiction:

Improvepolymer qualityVSAvoiddeposition speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system uses the polymer's own viscous resistance to generate heat through shear stress during nozzle rotation. The polymer's viscosity, which normally impedes flow, is converted into a heating mechanism that melts the polymer internally without requiring high nozzle wall temperatures, thus maintaining both quality and speed.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces thermal conduction heating (relying on nozzle wall temperature) with mechanical shear heating (using nozzle rotation). This substitution allows efficient polymer melting through mechanical energy conversion rather than thermal conduction, avoiding the trade-off between temperature and degradation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If the nozzle is made stationary for simple construction, then device complexity is reduced, but the ability to efficiently melt and extrude polymer is limited

Engineering Contradiction:

Improvenozzle structureVSAvoidextrusion speed

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The rotating nozzle serves multiple functions: it acts as the extrusion channel, provides shear heating through rotation, and controls polymer flow dynamics. This multi-functionality achieves efficient melting and high extrusion speed without requiring separate heating mechanisms or complex thermal management systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 allows for faster polymer extrusion and deposition, potentially increasing the speed of three-dimensional article manufacturing by effectively distributing heat and melting the polymer more efficiently within the nozzle.

Implementation Method 1

the polymer is viscously heated and melted by rotating the nozzle structure about an axis extending through the inlet and the outlet

Methodology Applied

Scientific EffectViscous heating: Viscous Heating

Implementation Method 2

introduce shear stress within the polymer, generating heat and melting it as it passes through

Methodology Applied

Scientific EffectShear stress: Shear Stress

Data Source

PatentUS11911949B2Rotating nozzle structure and method

Publication Date: 2024.02.27 WISCONSIN ALUMNI RES FOUND

AI summary

Aspects of the disclosure are directed to methods and apparatus involving the extrusion of polymers or other materials. As may be implemented in accordance with various embodiments, a polymer is delivered into an inlet of a nozzle structure having the inlet and an outlet. The polymer is viscously heated and melted by rotating the nozzle structure about an axis extending through the inlet and the outlet, therein facilitating extrusion of the melted polymer through the nozzle structure outlet. A polymer supply may deliver the polymer into the nozzle structure inlet, and a coupler may facilitation rotation of the nozzle structure. A driver may further operate to control rotation of the nozzle structure relative to the coupler, for instance by generating a rotational output that causes rotation of the nozzle structure.