Warhead Casing Fragmentation Pattern via Chemical Etching

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Solution Overview

Problem

Current methods for manufacturing fragmentation warheads are inefficient, costly, and limited in producing specific target-optimized patterns, particularly due to issues with metal liners, mechanical scoring, and electron beam welding, which result in voids, cracks, and reduced lethality.

Innovation Solution

A method involving the use of lithographic and additive processes to create stress raisers on warhead casings, allowing for the production of predictable fragmentation patterns using materials like HF-1 steel, adaptable to existing manufacturing processes, and suitable for complex patterns on artillery and mortar warheads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If metal liners are inserted into the warhead to create patterned fragments, then reliable fragmentation patterns are achieved, but manufacturing complexity and safety hazards increase due to voids and cracks in explosive fill

Engineering Contradiction:

Improvefragmentation pattern reliabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent removes the metal liner component entirely and replaces it with direct etching of the warhead casing. This extraction eliminates the liner-related manufacturing complexities including fitting gaps, void formation, and crack risks while maintaining fragmentation pattern reliability through direct casing modification.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical liner insertion method with a chemical etching process. Instead of physically inserting a metal liner to create fragmentation patterns, the invention uses chemical etchants to directly modify the casing surface, thereby eliminating mechanical fitting issues and associated safety hazards.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If mechanical scoring is used to create fragmentation patterns, then manufacturing is simplified, but the process becomes time consuming and machine intensive

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidmanufacturing speed

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces mechanical scoring processes with chemical etching. Instead of using machines to mechanically score the casing surface, the invention applies chemical etchants that dissolve the metal to create fragmentation patterns, thereby maintaining simplicity while dramatically improving productivity and eliminating machine-intensive operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If electron beam welding is used to score warhead cases, then fragmentation patterns are created, but the process is time consuming, machine intensive, and ineffective in reliably producing patterned fragments

Engineering Contradiction:

Improvefragmentation pattern reliabilityVSAvoidmanufacturing cycle time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent replaces electron beam welding with chemical etching. Instead of using high-energy electron beams to melt and weld material to create patterns, the invention uses chemical etchants to selectively remove material, thereby achieving reliable fragmentation patterns with significantly reduced processing time and without the need for complex welding equipment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If internal surfaces of artillery munitions are scored, then fragmentation patterns are created, but dimensional limitations of the fuze well opening make this impractical

Engineering Contradiction:

Improvefragmentation pattern precisionVSAvoidaccessibility to internal surface

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical scoring methods with chemical etching that can access internal surfaces through the fuze well opening. The chemical etchant can be introduced into the confined space and etch the internal surface without requiring large dimensional openings, thereby maintaining manufacturing precision while improving accessibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances the efficiency and effectiveness of warhead fragmentation, increasing lethality and versatility by producing consistent fragment patterns, reducing manufacturing time and costs, and accommodating various steel types, including HF-1 steel.

Implementation Method 1

a chemical etchant is introduced into the interior cavity of the warhead to etch a fragmentation pattern onto an interior surface of the warhead casing

Methodology Applied

Scientific EffectChemical etching:

Data Source

PatentEP4235088B1Method of creating a fragmentation pattern on a warhead

Publication Date: 2024.12.25 UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY

Figure 1A
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Figure 2A

AI summary

A method of creating a fragmentation pattern on the interior surface of a warhead (10), the method characterized by: inserting a 3-D printer through an opening (101) to an interior cavity of the warhead (10); and with the 3-D printer applying a protective material (1301) selectively to portions of the interior surface (103) corresponding to positive portions of the fragmentation pattern, thus to create stress raisers in the presence of an explosive blast wave.