Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-08-20
2001-01-30
Carone, Michael J. (Department: 3643)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C102S473000, C102S481000, C156S173000, C156S175000, C156S155000
Reexamination Certificate
active
06179944
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to ordinance devices and more particularly to thin-walled, light-weight, nonfragmenting warhead composite casings derived from thermosetting resin-impregnated carbon fibers and to the process of preparing the composite casings for use as explosive warheads and the like.
BACKGROUND OF THE INVENTION
When dealing with explosive ordnance it is important that precautions have been taken to assure that the ordinance is incapable of being accidentally exploded in high temperature environments. Warhead cook-off is the response of the explosive warhead to excessive thermal environments such as a fire or abnormally high temperatures. Cook-off is an undesirable reaction of the explosive which typically starts as a burning or deflagration process, but can continue into a detonation process if the explosive remains confined. The detonation of a warhead under such circumstances can cause severe property damage and loss of life. Thus, restricting cook-off reactions to merely burning of the warhead material will substantially improve the safety aspects of the warhead. For example, a number of prior art cook-off preventions include using casings of reinforced plastic which soften and fail on direct cook-off due to exposure to flame before the contained material attains cook-off temperature. However, this arrangement is ineffective when the casing is subjected to slow cook-off from indirect heating.
Other types of ammunition casings, formed from hardened materials, e.g. stainless steel, have met many of the needs of modern warfare, while failing to meet others. The choice of stainless steel, for example, has yielded casings which have a great deal of strength and have been able to withstand the rigors of combat. The main disadvantage of stainless steel casings, however, has been the reaction of the encased ammunition to heat. When the hardened shell has a melting point higher than the ignition temperature of the enclosed ammunition, the shell or casing contains the expanding gases created during the ammunition cook-off. When the pressure of these expanding gases is great enough, the casing ruptures generating damage and metal fragments. The prior art has addressed the problem of munition cook-off. For example, U.S. Pat. No. 4,991,513 describes means for providing vent holes in the munition casing using a mechanism to open or close the holes. U.S. Pat. No. 5,361,703 discloses a casing, which contains the charge, with an arrangement for opening the casing to vent the pressure before the casing attains a temperature where cook-off may occur. These prior technologies, however, have resulted in disadvantages such as increased weight, poor sealing of the casing, increased complexity requiring operator action to ready the munition, increased cost and various other disadvantages. In accordance with this invention, however, a carbon fiber composite munition casing is provided which has increased strength, lower weight, and lower cost, while retaining the insensitive characteristics when subjected to higher temperatures.
SUMMARY OF THE INVENTION
This invention is directed to a process of preparing thin-walled, nonfragmentary carbon composite warhead casings having increased strength, lower weight and at less cost while retaining the characteristics of a warhead capable of resisting cook-off at higher temperatures. More specifically, this invention relates to a method of preparing a thin-walled, non-fragmenting composite warhead casing which comprises impregnating a tow of carbon fibers with effective amounts of at least one liquid epoxy resin and wrapping the impregnated carbon fibers over a mandrel and maintaining the impregnated carbon fibers on the mandrel at ambient temperatures until the epoxy resin jellifies and subsequently heating the resin impregnated carbon fibers at temperatures ranging from about 125° to 175° F. until the epoxy resin cures on the carbon fibers to form the composite casing; said liquid epoxy resin characterized as having a low molecular weight and a low viscosity at ambient temperatures and a T(g) glass transition temperature ranging from about 200° F. to 250° F.
Accordingly, it is an object of this invention to provide a method of preparing a thermosetting resin-impregnated carbon fiber casing capable of losing its structural integrity at temperatures below the ignition temperature of the explosive in the casing.
It is another object of this invention to provide a thermosetting resin-impregnated carbon fiber casing for warheads having high tensile strength, comparatively low in weight and at less cost.
It is another object of this invention to provide a carbon fiber composite shell for encasing explosive material that will eliminate or minimize the likelihood of undesirable explosive reactions caused by high temperatures.
These and other objects of the invention are accomplished by the method of preparing the resin-impregnated carbon fiber casings disclosed herein.
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Evans George R.
Hannick John W.
Lam Robert G.
Monolo Joseph C.
Watson Jr. Fred W.
Bechtel, Esq. James B.
Beitey Daniel J.
Carone Michael J.
The United States of America as represented by the Secretary of
Tura, Esq. James V.
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