Combustible Sleeve With Textile Insert Prevents Fracture

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Solution Overview

Problem

Combustible sleeves for firearms are sensitive to fracture during handling, leading to potential breakage and escape of propellant powder, posing a security risk, and existing reinforcement methods increase the thickness of the sleeve wall, reducing its usable volume for powder absorption.

Innovation Solution

A cylindrical sleeve with a stretchy insert embedded in the coat wall, made from materials like polyurethane-cotton mixing yarn, designed to maintain the sleeve's mechanical strength while preventing crack formation and powder leakage, allowing for a thinner wall and increased powder capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the coat wall is made thinner to increase powder capacity, then the usable volume for powder absorption increases, but the mechanical strength and fracture resistance decrease

Engineering Contradiction:
Improveusable volume for powder absorptionVSAvoidmechanical strength and fracture resistance
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The sleeve combines combustible fiber material (nitro cellulose, cellulator) with a non-combustible textile insert (cotton yarn, polyurethane-cotton mixing yarn) to create a composite structure. The textile insert provides mechanical reinforcement and fracture resistance, while the combustible material maintains its primary function. This composite approach allows the coat wall to be thinner while maintaining sufficient strength.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The reinforcement is applied locally through an embedded textile insert rather than uniformly throughout the entire coat wall. The insert is positioned at critical locations where fracture resistance is most needed, allowing the rest of the coat wall to be thinner and maximize powder capacity while providing targeted strength enhancement.

Inventive Principle:
Principle #3Local quality

2Strength

If multi-layer reinforcement is added to increase fracture resistance, then the mechanical strength improves, but the coat wall thickness increases and usable volume decreases

Engineering Contradiction:
Improvefracture resistanceVSAvoidusable volume for powder absorption
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The textile insert is embedded within the combustible coat wall material, with the insert nested inside the sleeve structure. This nested configuration allows the reinforcement to be integrated within the existing wall thickness rather than adding external layers, maximizing the usable volume for powder absorption while maintaining fracture resistance.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Reliability

If traditional reinforcement methods are used to prevent breakage, then the reliability improves, but the manufacturing complexity and production time increase

Engineering Contradiction:
Improvehandling safety and breakage preventionVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The manufacturing process merges the insertion of the textile insert with the existing coat wall formation process. The insert is placed into the sieve shape before the combustible material is applied, combining two operations (insert placement and coat wall formation) into a single integrated manufacturing step, thereby reducing overall process complexity and time.

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 sleeve achieves enhanced mechanical strength and reduced sensitivity to fracture, ensuring safe handling and efficient powder retention without increasing the wall thickness, thereby maintaining a larger usable volume for propellant absorption.

Implementation Method 1

the insert now has the function of keeping the resulting cracks and break openings in the coat wall closed compared to the exit of the blades of the propellant

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

With the help of negative pressure, the sieve shape sucks the fiber porridge

Methodology Applied
Scientific EffectNegative pressure absorption: Suction

Implementation Method 3

at least temporarily heats up, which makes the sleeve form stable

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP3643826B1Cylindrical sleeve for propellant charge powder
Publication Date: 2022.11.30 NITROCHEM ASCHAU
  • EP3643826B1 patent drawingFigure 1
  • EP3643826B1 patent drawingFigure 2
  • EP3643826B1 patent drawingFigure 3

AI summary

The invention relates to a cylindrical sleeve (6) for receiving propellant powder (4) with a dimensionally stable jacket wall made of combustible, felted fiber material and an insert (5) made of a textile fabric in the jacket wall, and a method for its manufacture.