Multi-Part Projectile Coating for Threaded Interface Stability
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Solution Overview
Problem
Existing spin-stabilized projectiles face issues with threaded interfaces that fail under high torque due to increased weight and reduced payload capacity, leading to potential shearing or rotation, which affects accuracy and reliability.
Innovation Solution
Implementing a high-friction coating on the interface between projectile sections to enhance torque transfer and prevent relative rotation, using materials like tungsten carbide and alumina to increase frictional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If robust threaded interfaces are used to endure compression and high torques, then the strength of the threaded interface is improved, but the sidewall body thickness increases which adds weight and reduces payload carrying capacity
Solution Approach 1:
The patent applies a high-friction coating to the threaded interface surfaces, changing the surface property parameter (friction coefficient) to enhance torque transfer capability. This allows the threaded interface to withstand high torques without increasing the bulk dimensions or weight of the projectile body sections.
Solution Approach 2:
The patent uses a composite structure where a high-friction coating material is applied to the base metal surfaces of the threaded interface. This composite approach combines the structural integrity of the metal with the high-friction properties of the coating material to achieve superior torque resistance without adding significant weight.
2Reliability
If traditional knurling is used at the threaded interface to prevent rotation, then the anti-rotation capability is improved, but the dimensional control difficulty increases and reliability under high firing pressures is insufficient
Solution Approach 1:
The patent changes the surface friction parameter by applying a high-friction coating to the threaded interface. This provides consistent anti-rotation capability under high firing pressures without requiring tight dimensional tolerances on the knurling features, thereby improving reliability while reducing manufacturing precision requirements.
3Force
If the threaded interface is designed to transfer torque from the rotation band, then the torque transfer capability is improved, but the probability of shearing or thread failure increases when weight is reduced
Solution Approach 1:
The patent modifies the surface friction parameter by applying a high-friction coating to the threaded interface. This enhances the torque transfer capability of the interface, allowing lightweight projectile designs to still withstand the high torques generated during firing without experiencing shearing or thread failure.
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 high-friction coating significantly enhances the reliability and accuracy of projectiles by reducing the likelihood of thread failure and maintaining the projectile's trajectory, thereby improving payload delivery.
Implementation Method 1
A high-friction coating is disposed on at least one of the lands of one or both the front and back sections. The high-friction coating has a co-efficient of friction greater than the base materials the projectile is comprised of.
Data Source
AI summary
Described herein are multi-part projectiles that include a high-friction coating as part of an interface between parts of the projectile body. The high-friction coating reduces the probability that projectile parts coupled at the interface would rotate relative as the projectile is launched, thus enhancing the reliability and accuracy of the projectile. In one example, a multi-part projectile includes a projectile body having first and back sections coupled by an interface. The front section has a front land and the back section has a back land. The threaded interface restrains the rotation of the projectile body first and back sections. A high-friction coating is disposed on at least one of the lands of one or both the front and back sections. The high-friction coating has a co-efficient of friction greater than the parent metals against each other alone, without the high-friction coating disposed therebetween.