Polygon Cavity Tracer Projectile Adhesion

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Solution Overview

Problem

Jacketed tracer projectiles with metal cores for small-caliber and medium-caliber weapons face issues with the tracer charge becoming separated due to high pressures, temperatures, and vibrations during discharge, and require multiple components for attachment and protection, making them complex and costly.

Innovation Solution

A tracer projectile design featuring a polygon-shaped cavity with a surface roughness of 0.2-3.2 µm and a cone angle of 0.2-1.0° in the metal core, allowing for strong adhesion of the tracer device without additional components, using a machining process that includes creating a cavity and applying the tracer device via pressing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional tracer charge attachment methods are used (direct insertion or charge capsule), then the tracer charge can be easily installed, but the tracer charge becomes separated during discharge due to high pressures, temperatures, and vibrations

Engineering Contradiction:
Improvetracer charge installationVSAvoidtracer charge attachment stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The cavity cross-section is designed as a polygon shape (e.g., hexagon, star shape) rather than a circular shape, creating asymmetric geometric interlocking between the tracer charge and the metal core. This asymmetric geometry provides mechanical keys that prevent the tracer charge from rotating or detaching under the high pressures, temperatures, and vibrations during discharge, while still allowing for relatively simple installation through a pressing process.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If multiple components are used for tracer charge attachment and jacket protection (sealing wad, sealing disk, lacquer), then protection against combustion gases and moisture is improved, but the device complexity and cost increase

Engineering Contradiction:
Improveprotection against combustion gases and moistureVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges multiple protective functions into the polygon-shaped cavity structure itself. The cavity serves simultaneously as: (1) the attachment mechanism for the tracer charge through geometric interlocking, (2) the sealing structure that protects against combustion gases, and (3) the protective feature against moisture. This eliminates the need for separate sealing wads, sealing disks, and protective lacquers, thereby reducing component count and simplifying manufacturing while maintaining protection reliability.

Inventive Principle:
Principle #5Merging (Combining)

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 design ensures the tracer device remains attached during projectile rotation, simplifies manufacturing, and reduces costs by eliminating the need for extra components, while maintaining reliable attachment and protection.

Implementation Method 1

the cross section S1,2 of the cavity is polygon-shaped for strong adhesion to the interior walls of the cavity

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the cross section S1,2 of the cavity is polygon-shaped for strong adhesion between the tracer device and the cavity

Methodology Applied
Scientific EffectMechanical interlocking:

Data Source

PatentEP3278054B1Tracer projectile and method for the application of a tracer device in a tracer projectile
Publication Date: 2019.10.23 NAMMO VANASVERKEN
  • EP3278054B1 patent drawingFigure 1
  • EP3278054B1 patent drawingFigure 2~3

AI summary

The invention relates to a jacketed tracer projectile (1) intended for small-caliber and medium-caliber weapons comprising a metal core (3) comprising a tracer device (4), in particular in the form of a pyrotechnic tracer charge, disposed inside a cavity (5) in the metal core (3) in the rear part of the projectile (1), characterized in that the cavity (5) is designed to prevent the tracer device (4) from becoming separated from the cavity (5) during the discharge phase of the tracer projectile (1). The cross-sectional area S1,2 of the cavity (5) is typically of polygonal execution. The invention also relates to a method for the application of the tracer device (4) in the tracer projectile (1).