Polygonal Extractor Recess for Easier Cartridge Case Production

Solution Overview

Problem

Existing methods for producing cartridge cases with circumferential extraction grooves are complex and costly, requiring specialized tools and reshaping or machining processes.

Innovation Solution

The extractor recess in the base part is designed with a polygon geometry formed by a closed traverse in cross section, allowing for simplified production through reshaping or machining methods, using multi-part shaping dies to achieve high geometric precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a traditional circumferential rotational surface extraction groove is produced by reshaping, then the cartridge case can be manufactured, but a complex reshaping tool with multiple segments is required

Engineering Contradiction:

Improveease of productionVSAvoidtool complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by changing the extraction groove cross-sectional shape from a circular (symmetrical) form to a polygonal (asymmetrical) form. This asymmetrical polygonal geometry allows the extraction groove to be produced using simpler reshaping tools with fewer segments, as the polygonal shape can be formed by linear tool paths rather than requiring complex circular shaping tools with multiple segments.

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If the extraction groove is produced by machining methods, then the cartridge case can be manufactured, but the production process becomes complex

Engineering Contradiction:

Improveease of productionVSAvoidprocess complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by changing the extraction groove cross-sectional shape from a circular (symmetrical) form to a polygonal (asymmetrical) form. This asymmetrical polygonal geometry allows the extraction groove to be produced using simpler reshaping tools with fewer segments, as the polygonal shape can be formed by linear tool paths rather than requiring complex circular shaping tools with multiple segments.

Inventive Principle:

Principle #4Asymmetry

3Ease of manufacture

If a two-part cartridge case design is used, then the base part can be produced separately, but the production process becomes complex

Engineering Contradiction:

Improveease of productionVSAvoidproduction process complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by changing the extraction groove cross-sectional shape from a circular (symmetrical) form to a polygonal (asymmetrical) form. This asymmetrical polygonal geometry allows the extraction groove to be produced using simpler reshaping tools with fewer segments, as the polygonal shape can be formed by linear tool paths rather than requiring complex circular shaping tools with multiple segments.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS12366438B2Base part for producing a cartridge case and cartridge case, method for producing a base part for a cartridge case, and method for producing a cartridge case

Publication Date: 2025.07.22 DIEHL METAL STIFTUNG & CO KG

AI summary

A base part intended for producing a cartridge case has a case base for receiving a primer, wherein a peripheral extractor recess is provided on the outer circumference of the base part. To simplify production, the extractor recess has a polygonal geometry that is formed in cross section by a closed traverse.