Ammunition and explosives – Igniting devices and systems – Initiating devices
Reexamination Certificate
1999-07-08
2001-03-06
Jordan, Charles T. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Initiating devices
C102S275800, C102S275120, C102S202800, C102S202900
Reexamination Certificate
active
06196131
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the blasting industry and, more particularly, to an initiation device for use with non-electric shock tubes.
BACKGROUND OF THE INVENTION
It is known in the blasting industry to use initiation devices for initiating shock tube which, in turn, ignites a base charge. The shock tube contains a small quantity of gun powder that is ignited by a powerful percussion spark generated by the initiation device. The initiation of the gun powder causes the base charge coupled to the remote end of the shock tube to be ignited. This type of shock tube is commonly referred to as non-electric shock tube due to the fact that gun powder rather than electricity is used to ignite the base charge.
Conventional non-electric shock tube initiation devices used in the blasting industry include an initiator tip which contains electrical components for generating the spark that initiates the gun powder in the shock tube. The typical initiator tip comprises a standard coaxial cable connector and relies on generating a differential voltage between the inner conductor of the coaxial cable and the outer conductor of the coaxial cable to create the percussion spark.
One disadvantage of the conventional non-electric shock tube initiation device is that the inner electrode of the coaxial cable connector is comprised of copper, which is easily damaged by the high-temperatures produced by the percussion spark. Consequently, repeated firing of the initiation device destroys the tip of the inner electrode, which is housed in the initiator tip of the initiation device and which couples with the shock tube.
Another disadvantage of the conventional non-electric shock tube initiation device is that the coaxial cable connector that functions as the initiator tip is made of a conductive material. Therefore, if a person touches the initiator tip while current is being applied to the electrodes, the person will receive a high-voltage shock, thereby risking serious bodily injury and possibly death.
Accordingly, a need exists for an initiator tip for use with a non-electric shock tube initiation device which utilizes an inner electrode made of a relatively high-temperature conductive material that can withstand the high temperatures associated with firing the tip. A need also exists for an initiator tip which comprises an outer encasing made of an insulative material for eliminating the possibility of electric shock to a person using the initiation device.
SUMMARY OF THE INVENTION
The present invention provides a non-electric initiator tip for use with a nonelectric shock tube initiation device. The initiator tip of the present invention comprises an inner electrode, an outer electrode, and a conductive component electrically coupled to the inner and outer electrodes for applying current to the inner and outer electrodes to thereby cause a percussion spark to be generated. When the initiator tip is connected to an initiation device, the conductive component of the initiator tip is electrically coupled to electronics in the initiation device such that, when the initiation device is actuated, the electronics in the initiation device in conjunction with a power supply cause a voltage differential to be generated between the inner and outer electrodes and a percussion spark to be produced. The percussion spark initiates gun powder contained in a shock tube mounted to the initiator tip.
In accordance with one embodiment of the present invention, the initiator tip comprises an inner electrode made of a material having a high melting point, such as, for example, steel
ickel alloys (e.g., stainless steel SS-304, SS-306), chromium/molybdenum alloys, Tungsten, etc. In accordance with another embodiment of the present invention, the initiator tip is encased in an insulative material to eliminate any possibility of electric shock to a person handling the initiation device. In accordance with this embodiment, the inner electrode can be comprised of any conductive material, such as, for example, copper, although preferably a high-temperature material is used for this purpose.
In accordance with the preferred embodiment of the present invention, the initiator tip of the present invention comprises the features of the first and second embodiments, i.e., the inner electrode of the initiator tip is made of a material having a high melting point, such as, for example, steel
ickel alloys (e.g., stainless steel SS-304, SS-306), chromium/molybdenum alloys, Tungsten, etc., and the initiator tip is encased in an insulative material to eliminate any possibility of electric shock to a person handling the initiation device.
In accordance with another embodiment of the present invention, the initiator tip of the present invention comprises a conventional coaxial cable initiator tip encased in an insulative material to reduce the possibility of electric shock to a person handling the initiator tip.
These and other advantages of the present invention will become apparent from the following description, drawings and claims.
REFERENCES:
patent: 3754506 (1973-08-01), Parker
patent: 3971320 (1976-07-01), Lee
patent: 4128058 (1978-12-01), Mixon, Jr. et al.
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patent: 4576094 (1986-03-01), Meador
patent: 4621578 (1986-11-01), Valleres et al.
patent: 5659149 (1997-08-01), Sutula, Jr.
patent: 5703320 (1997-12-01), Lucca et al.
patent: 6006671 (1999-12-01), Yunan
Nodine John P.
Yanda Ronald A.
Jordan Charles T.
Sanchez Glenda L.
Thomas Kayden Horstemeyer & Risley, L.L.P.
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