Frustoconical Priming Relay for Low-Sensitivity Explosives

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Solution Overview

Problem

Explosives with reduced sensitivity, such as those incorporating Oxinitrotriazole, TATB, or Nitroguanidine, are difficult to initiate due to their increased critical diameter and reduced vulnerability to impact and temperature, leading to inefficient detonation and poor fragment distribution in ammunition, as conventional ignition relays struggle to provide sufficient energy for reliable initiation.

Innovation Solution

A frustoconical-shaped priming relay composition is placed in a blind cylindrical bore, with a conical side wall and increasing thickness towards the front end, allowing simultaneous initiation of the explosive charge and impact on the bore's internal surface, enhancing the effective priming surface area without increasing the relay's size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the diameter of the relay is increased to provide sufficient initiation energy for explosives with reduced sensitivity, then the initiation reliability is improved, but the volume reserved for the explosive charge is reduced

Engineering Contradiction:
Improveinitiation reliabilityVSAvoidvolume reserved for explosive charge
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The invention transitions from a conventional cylindrical relay to a frustoconical relay, utilizing the conical geometry to expand the effective priming surface area in a radial dimension. This dimensional change allows the relay to maintain a compact axial profile while providing sufficient initiation energy through increased surface contact with the explosive charge.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention changes the geometric parameters of the relay from a standard cylinder to a frustocone with specific angle ranges (30°-60°). This parameter modification optimizes the balance between initiation energy delivery and space efficiency, allowing reliable initiation of low-sensitivity explosives without compromising charge volume.

Inventive Principle:
Principle #35Parameter changes

2Volume of moving object

If a conventional cylindrical relay is used with explosives with reduced sensitivity, then the relay size is kept compact, but the initiation energy is insufficient leading to poor detonation

Engineering Contradiction:
Improverelay sizeVSAvoiddetonation reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The invention merges the priming function with the relay structure itself by utilizing the frustoconical side surface as an active priming surface. This integration allows the relay to deliver initiation energy through both its front end and its lateral surface, combining multiple initiation pathways within a compact form factor.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

By adopting a frustoconical geometry, the invention adds radial dimensionality to the initiation process. The sloped side surface provides additional surface area for energy transfer to the explosive charge, enhancing initiation reliability without increasing the axial length of the relay.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of operation

If the shock wave propagation path is blocked by the relay case in conventional designs, then the initiation direction is controlled, but the detonation symmetry is broken leading to poor fragment distribution

Engineering Contradiction:
Improveinitiation direction controlVSAvoiddetonation symmetry
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The frustoconical geometry introduces a controlled asymmetry in the relay structure that actually promotes symmetry in the detonation outcome. The sloped sides distribute the shock wave reflection patterns in a way that creates more uniform energy distribution around the charge, improving fragment distribution while maintaining directional initiation control.

Inventive Principle:
Principle #4Asymmetry

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 design ensures reliable initiation of both conventional and sensitive explosives by distributing the detonation wave effectively, maintaining symmetry and optimizing the explosive charge's mass utilization, while allowing for a reduction in relay size without compromising ignition performance.

Implementation Method 1

the impact of the frustoconical side wall on the internal cylindrical surface of the bore

Methodology Applied
Scientific EffectImpact force: Impact Force

Implementation Method 2

the propagation of the shock wave, which is difficult affected by the obstacles within the charge

Methodology Applied
Scientific EffectShock wave: Shock Wave

Implementation Method 3

relay composition which is detonated by an initiation means

Methodology Applied
Scientific EffectDetonation: Detonation

Implementation Method 4

an explosive detonation relay composition

Methodology Applied
Scientific EffectExplosion: Explosion

Data Source

PatentEP2244050B1Priming device for explosive charge
Publication Date: 2013.03.06 NEXTER MUNITIONS SA
  • EP2244050B1 patent drawingFigure 1
  • EP2244050B1 patent drawingFigure 2
  • EP2244050B1 patent drawingFigure 3~4

AI summary

The device has a priming relay composition (8) arranged in a one-eyed cylindrical boring (5) that is axially arranged in a reduced sensitivity explosive load (2). The relay composition is fixed in detonation by an initiation unit (9) i.e. flat wave generator. The relay composition is arranged in a case comprising a truncated side wall (17). The relay composition and the case are selected to initiate the load at a level of a front end (8a). The impact of the truncated side wall is projected on an internal cylindrical surface of the boring.