Solid Propellant Extrusion Nozzle Temperature Control

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Solution Overview

Problem

Existing methods for producing solid propellant elements, such as casting and molding, are limited in shape complexity and uniformity of properties.

Innovation Solution

The use of an additive manufacturing process involving extrusion through a heated nozzle to remove excess solvent from a propellant material, allowing for the creation of complex shapes and uniform properties in solid propellant elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If casting or molding methods are used to produce solid propellant elements, then the production process is simple, but the shape complexity and uniformity of properties are limited

Engineering Contradiction:
Improveshape complexityVSAvoiduniformity of properties
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The propellant element is manufactured layer by layer through additive deposition, dividing the manufacturing process into discrete sequential steps that allow complex geometries to be built up incrementally while maintaining uniform material properties throughout the structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The nozzle temperature is precisely controlled to maintain it above the boiling point of the solvent to remove excess solvent during extrusion, but below the decomposition temperature of the propellant material, thereby achieving uniform material properties while enabling complex shapes

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If excess solvent is added to propellant material for additive manufacturing, then the material is easier to extrude, but premature chemical reactions and thermal gradients may occur

Engineering Contradiction:
ImproveextrudabilityVSAvoidchemical stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The nozzle temperature is precisely controlled to maintain it above the boiling point of the solvent to remove excess solvent during extrusion, but below the decomposition temperature of the propellant material, thereby achieving uniform material properties while enabling complex shapes

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Excess solvent is actively removed from the propellant material during the extrusion process through the heated nozzle, extracting the harmful component before it can cause premature chemical reactions or thermal gradients

Inventive Principle:
Principle #2Taking out (Extraction)

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

Enables the production of solid propellant elements with improved shape retention, adhesion, and functionality, including the ability to produce pressurized gases upon activation, while avoiding premature chemical reactions and thermal gradients.

Implementation Method 1

the extruding occurs when the heated nozzle is at a temperature above a boiling point of the solvent... the extruding removes some of the solvent from the propellant material

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3423259B1Method of producing solid propellant element
Publication Date: 2020.02.12 RAYTHEON CO
  • EP3423259B1 patent drawingFigure 1~3

AI summary

A method of producing a propellant material element (12), such as an electrically-operated propellant material, includes extruding a propellant material (16) through a heated nozzle (20). The nozzle may be heated to a temperature that is above the boiling point of a solvent that is part of the propellant material, yet is below a decomposition temperature of the propellant material. This allows some of the solvent to be driven off during the extruding process, while still preventing initiation of an energy-creating reaction within the material. The heating of the material in the extruding process, and especially the heating of the nozzle that the material is extruded through, may be controlled to remove an amount of solvent that results in the extruded material having desirable properties.