Azido Polymer Combustible Containers via Reactive Injection Molding

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Solution Overview

Problem

Existing manufacturing processes for small-, medium-, and large-caliber combustible containers are costly, inefficient, and pose safety risks due to multi-step processes, high reject rates, and the use of solvent and volatile organic compounds.

Innovation Solution

The use of reactive injection molding of azido polymers to produce rigid combustible propellant containers and cartridge cases in a single-step process, which is cost-effective, safe, and allows for the creation of containers with adjustable burning properties and intricate geometries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the felting process is used to manufacture combustible cartridge cases, then rigid containers with good combustion properties are obtained, but manufacturing cost increases due to multi-step process

Engineering Contradiction:

Improverigidity of containerVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent combines multiple separate steps of the felting process (fiber preparation, slurry formation, molding, drying, and post-drying treatments) into a single injection molding operation where polymer particles are injected, heated to melt and fuse, then cooled to form the rigid container in one continuous process

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The injection molding process maintains continuous operation without the intermittent drying and post-treatment steps required by felting, keeping the manufacturing line continuously productive and eliminating idle time between operations

Inventive Principle:

Principle #20Continuity of useful action

2Strength

If the felting process is used to manufacture combustible cartridge cases, then rigid containers with good combustion properties are obtained, but reject rate increases due to poor deposition of pulp

Engineering Contradiction:

Improverigidity of containerVSAvoiddeposition quality

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical felting process (which relies on fiber deposition through screening and pressing) with an injection molding process where molten polymer is forced into the mold cavity under pressure, ensuring complete and uniform filling without deposition defects

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state of the material from dry fibers requiring aqueous slurry formation to thermoplastic particles that are melted and injected, fundamentally altering the processing parameters to eliminate deposition issues inherent in the felting method

Inventive Principle:

Principle #35Parameter changes

3Strength

If the felting process is used to manufacture combustible cartridge cases, then rigid containers with good combustion properties are obtained, but quality control cost increases

Engineering Contradiction:

Improverigidity of containerVSAvoidquality control cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The injection molding process incorporates real-time monitoring of injection parameters (pressure, temperature, flow rate) and automatic adjustment mechanisms that ensure consistent product quality without requiring extensive post-manufacturing inspection and quality control personnel

Inventive Principle:

Principle #23Feedback

4Strength

If the felting process is used to manufacture combustible cartridge cases, then rigid containers with good combustion properties are obtained, but safety issues arise due to post drying steps and presence of solvent and volatile organic compounds

Engineering Contradiction:

Improverigidity of containerVSAvoidsafety hazards from solvents

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent eliminates the need for solvent-based treatments and high-temperature post-drying steps by using thermoplastic polymers that are processed in a melt state and then cooled to form the container, converting a potentially harmful multi-step process with chemical exposures into a safer thermal processing operation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the processing parameters from low-temperature drying with solvent evaporation to high-temperature melting followed by controlled cooling, eliminating the need for solvent removal and associated safety hazards while still achieving the desired rigid container structure

Inventive Principle:

Principle #35Parameter changes

5Ease of operation

If cloth bags are used to contain propellant, then easy manipulation and removal is enabled, but protection against elements is insufficient leading to propellant destruction

Engineering Contradiction:

Improvemanipulation easeVSAvoidprotection against elements

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent uses composite materials consisting of polymer particles that fuse together to form a container that is both mechanically strong for protection and can be designed with features for easy manipulation, replacing the inadequate cloth bag material

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The injection molded container can be designed with appropriate wall thickness and structural features that provide robust protection against elements while maintaining flexibility for easy manipulation and removal by the user

Inventive Principle:

Principle #30Flexible shells and thin films

6Productivity

If reactive injection molding of azido polymers is used, then single-step production is achieved, but process complexity increases

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the manufacturing process into distinct phases within the injection molding machine: particle feeding, heating and melting, injection into mold, cooling and solidification, and ejection, with each phase automatically controlled by the machine's programming to manage complexity while maintaining high productivity

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 enables the production of combustible containers that are impervious to elements, reducing waste and environmental impact, while allowing for efficient manipulation and reuse of propellant charges, thereby enhancing operational and economic efficiency.

Implementation Method 1

reactive injection molding of azido polymers

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS12337511B2Combustible containers manufactured using reactive injection molding of azido polymers

Publication Date: 2025.06.24 GENERAL DYNAMICS ORDNANCE AND TACTICAL SYSTEMS CANADA INC

AI summary

Small-, medium-, and large-caliber combustible cartridge cases and propellant combustible containers that are manufactured using reactive injection molding of azido polymers. An injection process for a single propellant combustible charge including the steps of: providing a quantity of azido bearing polymer; providing a quantity of curing agent; optionally providing a quantity of chemical blowing agent; optionally providing a quantity of fibers; optionally providing a quantity of additives and catalysts; and providing a mold defining a male cavity, a female cavity, and an injection port. The injection process further includes mixing together the azido bearing polymer, the curing agent, the optional chemical blowing agent, the optional fibers, the optional additives and catalysts, and injecting the resulting mixture into the mold.