The inventions described herein may be manufactured, used and licensed by or for the U.S. Government for U.S. Government purposes.
The invention relates in general to munitions and in particular to lifting plugs for munitions.
Because of their weight, most separate-loading projectiles (munitions) include an eyebolt lifting plug. The plug is for lifting; to keep the fuze well clean, dry and free of foreign matter; and to protect the fuze well threads. At the firing location, the plug is removed and the appropriate fuze is inserted.
Insensitive Munitions (IM) requirements relate to safe storage and transportation of
munitions. For example, the accidental detonation of one munition should not cause a chain reaction of detonations of adjacent munitions. Also, in case of a fire, the increase in ambient temperature should not cause an explosive detonation. One way to help meet the IM requirements is to provide a vent in the munition. As the explosive in a munition begins to react due to an increase in ambient temperature, the temperature and pressure inside the munition increases. By relieving the pressure in the munition, the speed and violence of the reaction may be controlled.
It is an object of the invention to provide munitions that are safer to store and transport.
It is another object of the invention to provide a munition with a vent for relieving excess pressure.
A further object of the invention is to provide a munition with a vent that is normally closed but that opens with increased pressure and/or temperature in the munition.
Still another object of the invention is to provide a venting apparatus that may be used with existing munitions.
One aspect of the invention is a munition comprising a casing having a nose end and an opening in the nose end; a lifting plug disposed in the opening in the nose end, the lifting plug including a bore therethrough; and a seal disposed in the bore in the lifting plug, the seal comprising an ionomer.
The munition may further comprise a fuze well disposed in the casing, the opening in the nose end leading into the fuze well; and a second seal disposed in the fuze well. Preferably, the second seal also comprises an ionomer. In one embodiment, at least one of the seal and the second seal are solid. In another embodiment, at least one of the seal and the second seal has a hollow interior.
The munition may comprise an explosive disposed in the casing wherein, as the explosive is heated, the seal and the second seal will fail before the explosive detonates.
The invention will be better understood, and further objects, features, and advantages thereof will become more apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings.
In the drawings, which are not necessarily to scale, like or corresponding parts are denoted by like or corresponding reference numerals.
In one embodiment, the munition 10 is provided with both a fuze well seal 26 and a lifting plug seal 22. Due to a fire or other event, the munition 10 is exposed to an exothermal source. As the casing 12 heats up, the explosive payload 28 absorbs thermal energy. The explosive 28 starts to expand and exert pressure on the fuze well seal 26. The increase in temperature causes the fuze well seal 26 to soften. As the pressure continues to increase, the fuze well seal 26 ruptures. The explosive 28 then forces its way into the fuze well 24.
As more thermal energy is imparted to the casing 12, the lifting plug seal 22 softens and the explosive 28 continues to expand. The increasing pressure causes the lifting plug seal 22 to rupture. The explosive 28 is then exposed to the atmosphere and vents the built up pressure in the casing 12. When exposed to the hot atmosphere, the explosive 28 will ignite in a controlled manner due to the limited size of the fuze well opening. The explosive 28 will start to burn and spew from the casing 12 until all the explosive has either been expelled or burned. In this way, the munition 10 releases its explosive energy in a way that is less destructive than a detonation. Both seals 22 and 26 will fail before the pressure and temperature in the casing 12 are great enough to detonate the explosive 28. It is believed that the seal 26 fails at about 115 degrees Centigrade and the seal 22 fails at about 125 degrees Centigrade, with a corresponding pressure of about 60 psi.
Upon exposure to ambient heat, the casing 12 and fuze well 24 heat the expelling charge 46 and the seal 22. The seal 22 softens and the resultant increase in pressure from the expelling charge 46 will rupture the seal 22. The expelling charge 46 will burn off similar to explosive 28 described above. Without the expelling charge 46, the grenades 48 remain unarmed in the casing 12. Under continued heating, it is possible that one or more grenades 48 may explode. However, the grenades 48 remain in the casing 12, which helps to contain the explosion.
While the invention has been described with reference to certain preferred embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.
This application claims benefit under 35 USC 119(e) of provisional application 60/597,301, filed Nov. 22, 2005, the entire file wrapper contents of which provisional application are herein incorporated by reference as though fully set forth at length.
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Number | Date | Country |
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Number | Date | Country | |
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60597301 | Nov 2005 | US |