Lightweight Ammunition End Cap with Swept Volume Rebate
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Solution Overview
Problem
Conventional ammunition cartridges are heavy due to thick end caps, which increase the overall mass and reduce the number of rounds that can be carried or transported efficiently.
Innovation Solution
A lightweight unitary end cap with a swept volume rebate and an extractor groove, formed from a single piece of material, significantly reducing mass by up to 65% while maintaining structural integrity, using a combination of materials such as stainless steel and polymer inserts to achieve weight savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick end cap is used to ensure structural integrity, then strength is improved, but weight increases
Solution Approach 1:
The end cap features variable wall thickness with different zones optimized for specific functions: a thicker region (first radius) provides structural strength at the base, while a thinner region (second radius) reduces weight in areas where full thickness is not needed. This local differentiation resolves the contradiction by providing strength only where structurally necessary.
Solution Approach 2:
The end cap is segmented into distinct functional zones including a swept volume rebate, an extractor groove, and a primer recess. These segmented regions allow material to be strategically distributed - thicker where needed for strength, thinner where weight reduction is prioritized - thereby resolving the strength-weight contradiction.
2Weight of moving object
If material is removed to create a swept volume rebate, then weight is reduced, but structural integrity may be compromised
Solution Approach 1:
The swept volume rebate creates a localized thin-walled section (second radius) that reduces overall weight, while the surrounding thicker regions (first radius) maintain structural integrity. The local quality principle allows the thin-walled section to suffice for its specific function without compromising the overall structure.
Solution Approach 2:
The end cap may incorporate composite construction with a metal substrate providing structural strength and polymer inserts or coatings providing additional functionality with reduced weight. This composite approach allows aggressive material removal for weight reduction while maintaining strength through the metal framework.
Data Source
AI summary
A lightweight end cap for an ammunition cartridge, said end cap having a central axis along its axial length, with a first radius; wherein said end cap further comprises a swept volume rebate; having a second radius less than the first radius, wherein the second radius is at least 10% smaller than the first radius, and wherein the swept volume rebate extends along at least 10% of the axial length of said end cap, wherein the end cap further comprises an extractor groove suitable for receiving an ejection mechanism.