Polymer Ammunition Cartridge with Primer Insert
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Solution Overview
Problem
Conventional ammunition cartridges made from brass are heavy, expensive, and hazardous, and existing plastic ammunition fails to meet reliability and performance standards, particularly in terms of uniformity and safety, leading to issues like bullet displacement and pressure inconsistencies.
Innovation Solution
The development of polymer ammunition cartridges injection molded over a primer insert, featuring a polymer middle body with a propellant chamber and a thermal form to create a single-piece cartridge with a shoulder and neck, ensuring consistent ballistic performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If polymer ammunition cartridges are used instead of brass, then weight is reduced and cost is decreased, but reliability and performance consistency deteriorate due to bullet displacement and pressure inconsistencies
Solution Approach 1:
The patent applies preliminary action by pre-forming the polymer cartridge case with an integrated primer pocket and flash hole structure before bullet insertion. The primer insert is permanently molded into the case during the injection molding process, ensuring proper alignment and preventing bullet displacement before firing. This preliminary structuring eliminates the need for separate assembly steps that could compromise reliability.
Solution Approach 2:
The patent utilizes parameter changes by controlling the polymer material properties during injection molding, specifically adjusting the molding temperature and pressure parameters to achieve optimal case strength and dimensional consistency. The polymer is molded at elevated temperatures to ensure proper flow and filling of the case geometry, then cooled to achieve the required structural integrity for consistent ballistic performance across production batches.
2Ease of manufacture
If polymer material is used for cartridge cases, then manufacturing cost is reduced, but manufacturing precision deteriorates leading to inconsistent case dimensions and bullet-to-casing fit
Solution Approach 1:
The patent applies segmentation by dividing the cartridge case into distinct functional zones during injection molding: the main body, the primer pocket, and the flash hole aperture. The primer insert is molded as a separate integrated component within the case structure. This segmentation allows each zone to be optimized for its specific function while maintaining overall dimensional consistency through controlled molding parameters.
Solution Approach 2:
The patent replaces traditional mechanical assembly operations with injection molding technology. Instead of separately manufacturing the case and primer components then assembling them through mechanical fastening or adhesive bonding, the entire cartridge case with integrated primer pocket is formed in a single injection molding operation. This substitution eliminates assembly variability and achieves superior dimensional consistency while reducing manufacturing steps and cost.
3Weight of moving object
If plastic cartridge casings are made to be lightweight, then operational capabilities are improved, but structural integrity deteriorates causing casing breakage and weapon damage
Solution Approach 1:
The patent employs composite materials by combining polymer matrix material with reinforcing fibers or fillers during injection molding. The polymer case is reinforced with materials such as glass fibers, carbon fibers, or other high-strength additives to achieve the required structural integrity while maintaining lightweight characteristics. This composite construction provides the necessary strength-to-weight ratio for safe operation without the mass penalty of traditional brass casings.
Solution Approach 2:
The patent applies local quality by varying the polymer material properties and wall thickness in different regions of the cartridge case. The case features variable wall thickness with increased material density in high-stress areas such as the primer pocket, flash hole, and base regions, while maintaining thinner walls in less critical areas. This localized reinforcement ensures structural integrity where needed while preserving overall lightweight performance.
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
The solution provides lightweight, reliable, and cost-effective polymer ammunition cartridges that meet performance standards, ensuring consistent pressures and preventing issues like bullet displacement, while maintaining structural integrity and safety.
Implementation Method 1
heating the thermal form; inserting the unformed top end into the thermal form
Data Source
AI summary
The present invention provides a single piece polymer ammunition cartridge and polymer ammunition and methods of forming a single piece polymer ammunition cartridge and polymer ammunition.