Cartridge Case Base Piece Cold Forming for Accurate Extraction Grooves

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Solution Overview

Problem

Existing methods for producing extraction grooves in multi-part cartridge cases suffer from manufacturing tolerances and surface defects, leading to unreliable holding forces and increased production costs.

Innovation Solution

The extraction groove is produced by cold forming before the receptacle for the case jacket, ensuring higher dimensional accuracy and strength without surface defects, using simpler and less expensive tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the extraction groove is produced by machining, then the manufacturing cost and mass production efficiency are improved, but the manufacturing precision and surface quality deteriorate due to inability to ensure reliable holding forces and extraction function

Engineering Contradiction:

Improvemass production efficiencyVSAvoidextraction groove dimensional accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the manufacturing method from machining to cold forming, which fundamentally alters the material removal process to a plastic deformation process. This parameter change enables the extraction groove to be formed with superior dimensional accuracy and surface quality while maintaining high production efficiency suitable for mass manufacturing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The extraction groove is formed by cold forming before the final machining operations are performed on the base piece. This preliminary action allows the groove to be established with accurate geometry early in the manufacturing process, and subsequent machining operations can then focus on finishing other surfaces without compromising the groove's critical dimensions

Inventive Principle:

Principle #10Preliminary action

2Strength

If segmented punch and die tool arrangements are used to produce the extraction groove by deforming, then the holding force between base piece and case jacket is improved, but surface defects are generated that deteriorate the extraction function

Engineering Contradiction:

Improveholding forceVSAvoidsurface quality of extraction groove

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent extracts or removes the segmented tooling from the forming process and replaces it with a monolithic punch and die arrangement. This elimination of segmented components prevents the generation of surface defects at the extraction groove while still achieving the necessary deformation to create the groove geometry and ensure proper holding force

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using segmented tools that leave imperfections, the patent employs a single-piece punch that creates a continuous, defect-free surface in the extraction groove. The monolithic tooling copies the ideal groove geometry without the interruptions or misalignments that occur with segmented tool arrangements

Inventive Principle:

Principle #26Copying

3Adaptability or versatility

If the extraction groove is produced after the receptacle for the case jacket, then the manufacturing process flexibility is maintained, but the holding force and dimensional accuracy deteriorate

Engineering Contradiction:

Improvemanufacturing process flexibilityVSAvoidholding force

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent performs the cold forming of the extraction groove as a preliminary action before producing the receptacle for the case jacket. By establishing the groove geometry early in the forming sequence, the material flow and deformation patterns are optimized to ensure both the groove dimensions and the subsequent receptacle formation achieve their required specifications

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The manufacturing process is segmented into distinct sequential operations: first the extraction groove is formed by cold forming, then the receptacle for the case jacket is produced. This process segmentation allows each operation to be optimized independently, with the groove formation completing before the receptacle shaping begins, thereby ensuring both holding force and dimensional accuracy

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 achieves higher holding forces, reduces manufacturing costs by up to 30%, and ensures reliable extraction function with improved dimensional accuracy and material hardness.

Implementation Method 1

an extraction groove for engagement by a firearm ejector is produced by forming, in particular by cold forming

Methodology Applied

Scientific EffectCold forming: Cold-forming

Implementation Method 2

The extraction groove is produced by cold forming before the receptacle for the case jacket, ensuring higher dimensional accuracy and strength

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS12601573B2Method and tool for producing a base piece of a multi-part cartridge case, base piece and cartridge case

Publication Date: 2026.04.14 RUAG AMMOTEC AG

AI summary

A method for producing a base piece for receiving a primer for a multi-part cartridge case may include producing (e.g., by deforming) an extraction groove for engagement by a firearm ejector. The production of the extraction groove may be before a receptacle for a case jacket of the multi-part cartridge case for receiving a projectile is produced, such as by deforming. A tool arrangement for producing a base piece may be used to produce the base piece.