Ammunition and explosives – Igniting devices and systems – Holders for fuse or fuse cord to blasting cartridge,...
Reexamination Certificate
1998-10-30
2001-02-06
Johnson, Stephen M. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Holders for fuse or fuse cord to blasting cartridge,...
C089S034000, C089S035010, C206S317000
Reexamination Certificate
active
06182573
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of attachment systems. More particularly, it concerns systems for attaching one or more explosive device(s) to a flexible linear support, related methods and devices, and methods of using the charge assemblies thus produced.
2. Description of Related Art
An Anti-Personnel Obstacle Breaching System (APOBS) has been under development for the United States Marine Corps by the Naval Surface Warfare Center (NSWC). The system contains one Rocket Motor, a Line Charge Assembly (LCA) which contains detonating cord and 108 evenly spaced grenades, a single or multiple fuze assemblies, a parachute assembly, two backpack sets, and a shipping container. The APOBS system is designed to clear a safe lane (approximately 0.6-2.0 meters wide by 45 meters long) through wire obstacles containing anti-personnel landmines.
The current LCA design supports the evenly spaced grenades using two parallel 0.25 inch nylon ropes. The grenades are secured to the ropes via twin metal band clamp assemblies. The ropes are designed to be structural members that carry all of the grenade launch and deceleration loads. In addition, the detonating cord running through the center of each grenade is routed with adequate slack to minimize launch induced tensile loads on the cord, i.e., the rope carries the weight of the grenades, grenade attachments, and detonating cord.
Current system grenade attachment specifications prescribe labor-intensive processes that require highly specified and non-standardized components, numerous calibrations and quality checks, and expensive, one-of-a-kind clamping machines. Structural inadequacies, grenade separation and attachment degradations reducing storage life and performance reliability were noticeable problems during the development phase of the APOBS program. The structural support, spacing, and orientation control for the grenades during deployment and impact has also been an area of ongoing concern.
Though the band clamp attachment approach has been demonstrated to adequately support the grenades during deployments, the overall attachment performance and manufacturing processes have proven to be less than satisfactory. A key design feature of the structural attachment mechanism of the band clamp approach was that the clamps allow the ropes to predictability slip under the bands during deployment (shock) loading (2.0 inch slippage maximum). This predictable energy-absorbing rope slippage provided a shock absorption feature that reduced overall loads throughout the line charge assembly. However, the metal clamp edges tended to cut and fray the rope. In addition, the clamping action tended to pinch the outer layer of the dual braided nylon rope allowing only the inner braid to slip under the band—resulting in all the loads being carried by the damaged outer braid—resulting in premature rope failure.
The grenades are stowed in their backpack containers 90° to the direction of deployment, i.e., the ropes are first pulled perpendicular to the grenade axis. After the initial snatch, the grenades align with the deployment direction because the center of gravity of the grenade is behind the forward clamping band. The highest loads are experienced during the initial snatch, and this loading tends to pull the ropes circumferentially under the bands towards the rope pull side of the grenade. This circumferential slippage misaligns the axis of the grenade with the direction of deployment and reduces the maximum load carrying capability of the attachment.
Therefore, an attachment system that prevents rope fraying and misalignment would, among other factors, increase the performance and load carrying capabilities, and would thus represent a significant advance in the art.
SUMMARY OF THE INVENTION
The present invention overcomes these and other limitations present in the art by providing attachment systems that overcome the design and performance limitations present in the explosive device attachments utilizing one or more metal band clamp(s) alone.
The invention provides a system for attaching at least a first explosive device to at least a first flexible linear support, the system comprising at least a first fibrous band operatively connecting the at least a first explosive device to the at least a first flexible linear support. In certain aspects of the invention, the at least a first explosive device is a grenade. In other aspects of the present invention, the at least a first flexible linear support is a rope, a wire, a chain, a cord, webbing or a cable. In certain preferred embodiments, the at least a first flexible linear support is a rope.
In particular aspects of the invention, the at least a first fibrous band comprises a thread or a yarn wound around the at least a first explosive device and the at least a first flexible linear support. In preferred embodiments, the at least a first fibrous band comprises a thread. Threads contemplated for use in the present invention include, but are not limited to, nylon, polyester, polypropylene, Nomex®, Teflon®, Tenara® expanded PFTE, and Kevlar® threads, and blends thereof, for example nylon and Kevlar® threads. In preferred embodiments, the at least a first fibrous band comprises nylon thread. In certain embodiments, the thread is prestressed prior to winding around the at least a first explosive device and the at least a first flexible linear support.
In preferred aspects of the invention, the at least a first fibrous band comprises a thread wound around the at least a first explosive device and the at least a first flexible linear support between about 40 and about 70 times. In particular aspects, the at least a first fibrous band comprises a thread wound around the at least a first explosive device and the at least a first flexible linear support about 45, about 47, about 50, about 53, about 55, about 60, about 64, about 65, about 68 times or any other intermediate value. In other preferred aspects of the invention, the at least a first fibrous band comprises a thread wound around the at least a first explosive device and the at least a first flexible linear support at between about 6 and about 8 pounds of tension. In more preferred aspects, the at least a first fibrous band comprises a thread wound around the at least a first explosive device and the at least a first flexible linear support at about 7 pounds of tension.
In alternative embodiments of the present invention, the at least a first fibrous band comprises a yarn. In preferred embodiments, the at least a first fibrous band comprises Vectran™ yarn. Yarns having various denier values are contemplated for use in the present invention, with yarns of about 1500 denier being particularly preferred. In other preferred aspects, the at least a first fibrous band comprises a yarn with a fiber to resin ratio of about 60:40.
In certain aspects of the invention, the at least a first fibrous band comprises a yarn wound around the at least a first explosive device and the at least a first flexible linear support between about 30 and about 50 times. In particular embodiments, the at least a first fibrous band comprises a yarn wound around the at least a first explosive device and the at least a first flexible linear support about 32, about 35, about 37, about 40, about 43, about 44, about 45, about 46, about 49 times or any other intermediate value. In further aspects, the at least a first fibrous band comprises a yarn wound around the at least a first explosive device and the at least a first flexible linear support at between about 7 and about 9 pounds of tension. In particularly preferred embodiments, the at least a first fibrous band comprises a yarn wound around the at least a first explosive device and the at least a first flexible linear support at about 8 pounds of tension. In still other aspects of the present invention, the at least a first fibrous band comprises a blend, for example a blend of distinct threads, a blend of distinct yarns, or a blend of a thread and a yarn, wound a
Haggard Roy A.
Richards Les H.
BAE Systems, Inc.
Fulbright & Jaworski LLP
Johnson Stephen M.
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