Munition Shell Groove Machining for Safe Disposal
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Solution Overview
Problem
Existing methods for opening munition shells to remove explosive material often result in contamination of water, known as 'pink water,' which poses a disposal problem and risks detonation due to inaccurate penetration and spark generation.
Innovation Solution
A method involving machining a groove along a parting line on the shell's outer surface to divide it into two parts without penetrating the inner chamber, using ultrasonic thickness measurement for accuracy and avoiding water contact with explosives, thus preventing spark-induced detonation and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a compressed water jet is used to cut through the shell, then the shell can be opened, but water becomes contaminated with explosive material creating pink water disposal problems
Solution Approach 1:
The patent replaces the water jet cutting system with a mechanical cutting system. A circular cutting tool with cutting edges mechanically cuts through the shell wall along a parting line, eliminating the need for water as a cutting medium and thereby preventing explosive material contamination of water.
Solution Approach 2:
The patent extracts the harmful element (water) from the cutting process. By removing water from the system and using dry mechanical cutting instead, the source of pink water contamination is eliminated while still achieving shell opening.
2Manufacturing precision
If the water jet is aimed tangentially to determine cut depth, then penetration depth can be controlled, but it is difficult to penetrate the wall to an accurate depth and risks producing pink water or failing to crack open the munition
Solution Approach 1:
The patent replaces the tangential water jet method with radial mechanical cutting. The circular cutting tool approaches the shell radially with the cutting edges perpendicular to the shell surface, allowing direct visual and tactile feedback for precise depth control without the geometric uncertainties of tangential jetting.
Solution Approach 2:
The patent incorporates feedback mechanisms where the operator can visually observe and tactilely feel the cutting progress, allowing real-time adjustment to achieve the desired groove depth that weakens but does not penetrate the shell, thereby preventing pink water generation while ensuring reliable opening.
3Manufacturing precision
If a machine tool is used to machine the groove, then the groove depth can be determined with greater accuracy, but sparks may be generated risking detonation of the explosive material
Solution Approach 1:
The patent creates an inert or non-sparking environment by using cutting tools and methods that do not generate sparks. The circular cutting tool is designed to cut without spark generation, and the process is performed in an environment that prevents ignition of explosive materials, thereby eliminating the detonation risk while maintaining cutting precision.
4Device complexity
If the shell wall thickness is assumed uniform, then the cutting process can be simplified, but the assumption may not hold due to manufacturing irregularities resulting in inaccurate cuts
Solution Approach 1:
The patent performs preliminary measurement of the shell wall thickness at multiple locations before the cutting operation. This advance knowledge of actual thickness variations allows the operator to adjust the cutting depth accordingly, ensuring accurate groove formation despite non-uniform wall thickness caused by manufacturing irregularities.
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 method accurately opens the shell without creating 'pink water' and avoids detonation risks by ensuring the cutting tool does not penetrate the inner chamber, allowing for safe disposal and recycling of explosive material.
Implementation Method 1
the thickness of the shell at all points on the parting line is determined ultrasonically prior to commencement of machining and the remaining depth of material is determined during machining by subtracting a measured depth of the machined groove from the previously measured thickness of the shell
Data Source
AI summary
A method is described for safely opening the shell of a munition (10) having an inner chamber containing an explosive material. The method comprises the steps of machining a groove (20) into the shell along a parting line that encircles the outer surface of the munition and divides the shell into two parts. The groove (20) is of sufficient depth to weaken the shell but not to penetrate into the inner chamber of the munition. After machining the groove (20), the shell is cracked open by prising the two parts of the shell apart by inserting a suitable implement into the groove.