Single-Piece Polymer Ammunition Casing With Blow-Molded Undercuts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polymer ammunition casings face challenges in injection molding due to severe undercuts and tapered regions, leading to multi-piece designs and inadequate retention mechanisms, with no mention of carbon nanotube or graphene additives to address visco-elastic behavior under tension loads.
Innovation Solution
The use of injection stretch blow molding with carbon nanotube and graphene platelet additives in a single-piece polymer casing, incorporating a combination of advanced materials and manufacturing processes to create a casing with severe undercuts and precise thin walls, enhancing mechanical and thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional injection molding is used to manufacture polymer casings, then the manufacturing process is simple, but severe undercuts and tapered regions make it impossible to mold single-piece casings, requiring multi-piece construction
Solution Approach 1:
The patent changes the physical state parameters of the polymer material by incorporating carbon nanotube and graphene platelet additives, which modify the material's flow characteristics and strength properties during injection molding, enabling single-piece casings with severe undercuts to be manufactured
Solution Approach 2:
The patent uses composite polymer materials containing carbon nanotubes and graphene platelets mixed with base resin, creating a material with enhanced mechanical properties that allows single-piece injection molding of casings with severe undercuts and tapered regions that would be impossible with conventional polymers
2Ease of manufacture
If multi-piece casing designs are used, then severe undercuts can be avoided in molding, but non-trivial attachment means are required between pieces and projectile retention is compromised
Solution Approach 1:
The patent creates a homogeneous single-piece polymer casing without joints or interfaces between multiple components, eliminating attachment issues and providing uniform material properties throughout, which ensures reliable projectile retention through the integrated casing structure
3Ease of manufacture
If traditional polymer base resins are used, then manufacturing cost is low, but the inherent visco-elastic behavior causes stress relaxation and creep under long term tension load, loosening projectile fit over time
Solution Approach 1:
The patent incorporates carbon nanotubes and graphene platelets into the polymer base resin to create a composite material that maintains low manufacturing cost while dramatically improving dimensional stability, eliminating stress relaxation and creep behavior under long term tension loads through the reinforcement provided by the nanoscale additives
4Reliability
If single-piece polymer casings with severe undercuts are manufactured, then projectile retention is improved, but conventional injection molding cannot achieve the required geometric complexity
Solution Approach 1:
The patent modifies the material parameters by adding carbon nanotube and graphene platelet reinforcements to the polymer, which change the material's flow behavior and strength characteristics during injection molding, enabling the formation of severe undercuts and complex geometries in single-piece casings that would be impossible with conventional polymers
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 results in a low-cost, high-strength, single-piece polymer casing with improved projectile retention and resistance to heat and pressure waves, maintaining consistent wall thickness and dimensional stability.
Implementation Method 1
using a heater (25), directly heating the neck of the casing while not directly heating the base of the casing
Implementation Method 2
using a heater (25), directly heating the neck of the casing while not directly heating the base of the casing
Implementation Method 3
inserting a stretch rod (27) into the blind hole and stretching the neck from a first length (41) to a second length (42)
Implementation Method 4
pressurizing the blind hole with an air pressure causing the neck of the casing to be blow molded into a fourth state (11d)
Data Source
AI summary
A method of manufacturing a casing for an ammunition cartridge includes injection molding a polymer forming the casing using an injection mold. The casing is cylindrically shaped along a longitudinal axis extending from a base to a distal end with a blind hole formed therein. The blind hole has a primer retention feature disposed at the base and leads into a flash hole. An insulator and/or reflector is placed around at least a portion of the casing separating the base from the neck. A heater directly heats the neck of the casing while not directly heating the base. A stretch rod is inserted into the blind hole stretching the neck. The casing is inserted into a blow mold and pressurized causing the neck of the casing to be blow molded. At least a portion of the distal end of the casing is removed.