Ammunition Fuze Deconfinement via Shearable Synthetic Ring

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Solution Overview

Problem

Existing ammunition fuzes face challenges in achieving reliable and reproducible deconfinement while maintaining mechanical strength, particularly in smaller calibers where radial size constraints are a concern, as previous solutions are either too bulky or compromise mechanical resistance.

Innovation Solution

A priming fuze with a smooth external cylindrical surface featuring a sliding ring bearing a thread, integral with the fuze body via longitudinal keys, and a shearable annular ring made of synthetic material, such as PTFE, which forms an axial stop and ensures deconfinement upon temperature rise without compromising mechanical resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fusible plastic ring is used to ensure deconfinement by melting, then deconfinement function is achieved, but it is difficult to find a material that can both withstand firing constraints and melt quickly and reproducibly

Engineering Contradiction:
Improvedeconfinement reliabilityVSAvoidmaterial compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention divides the connection system into separate functional components: a steel connecting ring for mechanical strength during firing, and a synthetic material snap ring for deconfinement. This segmentation allows each component to be optimized for its specific function without compromise.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The steel connecting ring acts as an intermediary between the fuze and projectile body, providing the mechanical connection that must withstand firing constraints, while the synthetic snap ring provides the deconfinement function. The intermediary structure allows both functions to coexist.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If an intermediate ring with shearable ring is used for deconfinement, then deconfinement is achieved, but the device becomes relatively bulky radially

Engineering Contradiction:
Improvedeconfinement functionVSAvoidradial size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The invention merges the connecting ring and snap ring into a single integrated component. The snap ring is positioned within the connecting ring structure, eliminating the need for separate intermediate rings and reducing radial bulk while maintaining deconfinement functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The snap ring is nested within the connecting ring structure, with the snap ring positioned in a groove of the connecting ring. This nesting arrangement allows the deconfinement mechanism to be housed within the connection mechanism, reducing overall radial dimensions.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Reliability

If a shearable intermediate ring is added to the connecting ring, then deconfinement is enabled, but the mechanical resistance of the fuze/projectile connection is weakened

Engineering Contradiction:
Improvedeconfinement capabilityVSAvoidmechanical resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention segments the deconfinement function from the mechanical connection function. The steel connecting ring maintains mechanical strength for firing constraints, while the synthetic snap ring provides the shearable deconfinement mechanism. This segmentation prevents weakening of the primary connection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The snap ring is made of synthetic material with specific local properties (lower strength, higher ductility) only where needed for deconfinement, while the main connecting ring maintains high strength steel properties for mechanical resistance. This local quality differentiation allows both functions to coexist.

Inventive Principle:
Principle #3Local quality

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

The solution provides reliable and reproducible deconfinement with reduced radial size, maintaining excellent mechanical strength and facilitating deconfinement through the shearable ring's material properties, ensuring effective release of the rocket without unscrewing due to mechanical vibrations.

Implementation Method 1

a shearable annular ring 10 made of a synthetic material, such as PTFE, which forms an axial stop and ensures deconfinement upon temperature rise

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

The ring 4 is also made integral in rotation with the body of the rocket 1 by at least one longitudinal key 6

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2703769B1Device for the deconfinement of an ammunition casing
Publication Date: 2015.12.23 NEXTER MUNITIONS SA
  • EP2703769B1 patent drawingFigure 1
  • EP2703769B1 patent drawingFigure 2
  • EP2703769B1 patent drawingFigure 3~4a

AI summary

The fuse (1) has an externally smooth cylindrical bearing (3) on which a steel slip ring (4) carrying a threading (4a) on its external surface is positioned in slipping manner. The threading is intended to cooperate with a tapping (5) of an ammunition envelope (2a). The ring is made interdependent in rotation form a body of the fuse by a key (6). A shearable snap ring (10) forms an axial thrust for the slip ring during consecutive sliding motion of the slip ring with an assembly of the fuse on the envelope. The snap ring includes an annular form, and is placed in a groove of the fuse. The snap ring is made of a synthetic material.