Patent Publication Number: US-2022213005-A1

Title: Coreless-coil shock tube system with reduced noise

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of U.S. patent application Ser. No. 16/814,084, filed on Mar. 10, 2020, which is a nonprovisional application of U.S. Provisional Application Ser. No. 62/908,652, the contents of which are incorporated by reference herein 
    
    
     BACKGROUND 
     The subject matter disclosed herein relates to igniting devices and systems for explosives and, more particularly, to fuse cord and packaging for fuse cord. 
     Shock tubes are a type of fuse cord or blasting cord used in non-electric blast initiation systems. Shock tubing typically comprises an elongated, hollow, flexible, small-diameter tube, the inner surface of which is coated with a reactive substance, e.g., a thin layer of detonating or deflagrating explosive composition. Most commonly, this composition consists of a mixture of HMX and aluminum powder. Other shock tube designs encompass multiple plastic layers to provide improved tensile strength and abrasion resistance. 
     In commercial blasting applications, the shock tubing provides a signal transmission device to transmit a signal to multiple blasting caps in mining or quarrying applications. When initiated, the interior coating of the shock tube transmits a low energy shock wave that travels down the interior of the tube, but without breaching the tube sidewall. A detonator affixed to the end of the tubing is initiated by the shock wave, thereby setting off an attached explosive charge. In military applications shock tube-based initiation systems are used because of their relative safety. In particular, since the system is non-electric, it is not affected by stray electrical currents so cannot be accidentally initiated by electrical signals. Also, the system does not require special electrical blasting machines as would be required if an electric blasting cap system was used. 
     In commercial applications, a firing device containing a percussion primer is typically used to initiate the shock tube. For military applications, a self-contained system is desirable. In military systems, an end fitting can be used to position a percussion primer on the end of the shock tube. 
     In the field, a spring-loaded firing pin device is typically attached to the assembly and used to fire the percussion primer for initiating the shock tube. 
     Still other shock tubes have been developed for the military with the firing device permanently affixed to the shock tube lead in the factory. This results in a totally self-contained initiation system being delivered in one package to the field. The length of shock tube on a spool can vary from 80 feet to 1,000+ feet. The length of shock tube allows the field blaster to retreat a safe distance between the charge the detonator is initiating and the firing device that initiates the blast. This system is very robust and useful and has been deployed extensively in military field applications. However the use of a spool (and, of course, box) greatly increases the overall weight and volume of the shock tube package. For covert operations, it is extremely desirable to have a self-contained detonator assembly that is easily carried by a person or one that will fit into a pocket on a vest. 
     It should be appreciated that in covert operations it is desired to keep noise associated with the deployment of the shock tube to maintain an element of surprise during a mission. Without being limited by any theory, it has been found that in some instances the rubbing of the shock tube against the washers or end plates of the shock tube assembly, including the heat shrink skin, creates a resonance that amplifies the sound level. 
     Accordingly, while existing shock tubes are suitable for their intended use the need for improvement remains, particularly in providing a shock tube that generates less noise during deployment. 
     BRIEF DESCRIPTION 
     According to one aspect of the disclosure a shock tube package system is provided. The system includes a coreless bundle of shock tubing. The system further includes an outer covering disposed about the periphery of the bundle of shock tubing. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the outer covering being made from a flexible or elastic material. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the outer covering being made from a textile material. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the outer covering having a first end and a second end, the second end having a neck portion. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the neck portion being configured to move from a first size to a second size when the bundle of shock tubing is inserted into the outer covering. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the neck portion is further configured to move from the second size to the first size after the bundle of shock tubing is inserted. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the outer covering being a compression fit over the bundle of shock tubing. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include an initiator device operably coupled to the outer covering. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the initiator device being coupled to the outer covering by a removable strap or an elastic member. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the strap or elastic member being integral with the outer covering. 
     According to one aspect of the disclosure a method of deploying a shock tube system is provided. The method includes providing a shock tube system having a coreless bundle of shock tubing, and a flexible or elastic outer covering disposed about the periphery of the bundle of shock tubing, the system having a detonator coupled to one end of the bundle of shock tubing and an initiator coupled to an opposite end of the bundle of shock tubing. The detonator is removed from an interior of the bundle of shock tubing and coupling it to a desired charge. The bundle of shock tubing is uncoiled through an opening in the outer cover with the sound level from the uncoiling being below a predetermined level. A predetermined distance is moved from the detonator. The initiator device is actuated. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the method may include expanding a neck portion of the outer cover when inserting the bundle of shock tubing. In addition to one or more of the features described herein, or as an alternative, further embodiments of the method may include the outer covering being a compression fit over the bundle of shock tubing. 
     According to one aspect of the disclosure a shock tube system is provided. The system including an outer covering having first end with a centrally disposed first opening and a second end with a neck portion and a second opening. A bundle of shock tube is disposed within the outer covering, the bundle of shock tube having a first end configured to extend through one of the first opening or the outer covering, and a second end configured to extend through the second opening. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the outer covering is formed from a flexible or elastic material. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the outer covering being a compression fit over the bundle of shock tube. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include a detonator coupled to the second end of the bundle of shock tube. 
     In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include an initiator device coupled to the first end of the bundle of shock tube. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the initiator device being removably coupled to the outside cover. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the detonator being removably disposed within an interior portion of the bundle of shock tube. In addition to one or more of the features described herein, or as an alternative, further embodiments of the system may include the outer covering being made from a textile material. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The subject matter, which is regarded as the disclosure, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view of a coreless-coil shock tube system, according to an embodiment, showing an “outer” end of the shock tubing; 
         FIG. 2  is a perspective view of the shock tube system showing an “inner” end of the shock tubing; 
         FIG. 3  is a lateral side elevation view of the shock tube system; and 
         FIG. 4  is a lateral side elevation view of the shock tube system in accordance with another embodiment. 
     
    
    
     The detailed description explains embodiments of the disclosure, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION 
     Embodiments provided herein disclose a shock tube system that allows for deployment of a shock tube with lowered noise generation. 
     With reference to  FIGS. 1-3 , an embodiment of the present invention relates to a coreless-coil shock tube package system  20 . The package system  20  includes a “coreless” bundle of shock tubing  22 , by which it is meant that the tubing bundle  22  is not supported or contained by being wrapped around a spool or other supporting structure. The tubing bundle may be a generally cylindrical (in overall shape) coil of shock tube. Also, a flexible or elastic outer cover or envelope  28  at least partially covers or is disposed about the periphery of the coil  22 . 
     In an embodiment, one end of the tubing  22  (the “inner” end  30 ) is positioned at the interior  24  of the coil  22 , and the other end of the tubing (the “outer” end  32 ) is positioned on the outside of the coil. Alternatively (see  FIG. 3 ), a detonator  34  is attached to the tubing&#39;s inner end  30  and is then tucked into the coil  22 , through opening  40  in the outer cover  28 , for convenient storage and transport. Also, a percussive initiator device (“igniter”)  36  may be attached to the tubing&#39;s outer end  32  and secured in place against the outer covering  28 . In an embodiment, the initiator device  36  is removably coupled to the outer cover  28  using a strap  33 , such as an elastic band strap or a textile or fabric strap having a hook and loop fastener for example. In an embodiment, the connection means for holding the initiator device  36  is integrated into the outer covering  28 . 
     In use, the detonator  34  is removed from the coil  22  by pulling on a portion of the tubing  22  left protruding through a central hole  40  in the neck portion  26  of outer cover  280 . Alternatively, a pull string or tab  27  ( FIG. 4 ) may be attached to the detonator  34  or proximate tubing for use in removing the detonator from the coil interior  24 . Then, the detonator  34  is attached to an explosive charge or device (not shown) in a conventional manner. To deploy the tubing  22 , the coil package  20  is pulled away from the detonator and explosive, thereby uncoiling the tubing through the opening  40  and out of the outer covering  28 . Then, once at a safe distance, the igniter  36  is actuated, igniting the shock tubing  22 , which in turn actuates the detonator, igniting the explosive. It should be appreciated that in some embodiments, such as those used in military applications, it is desirable to uncoil the tubing with little noise. 
     The shock tube coil  22  can be any length as desired, from tens to hundreds of feet in length or more. The shock tubing  22  may be similar to that described in U.S. Pat. No. 4,328,753, or the shock tubing as described in U.S. Pat. No. 5,597,973, the contents of which are incorporated by reference herein their entirety. In this embodiment, the shock tubing  22  has an outside diameter between 0.08 inches and 0.12 inches. In an embodiment, the outside diameter may be 0.085 inches, 0.100 inches, or 0.118 inches. It should be appreciated that the dimensions provided herein are for example purposes and the size may be changed without deviating from the teachings herein, and the claims should not be so limited. This size of small-diameter shock tubing will yield the desired degree of resiliency and stress at the inside diameter of the coiled shock tubing, after removal from a mandrel in the manufacturing method described below. However, as should be appreciated, shock tubing with different diameters may be used. 
     The outer covering  28  may be a flexible or elastic material. In an embodiment, the outer covering  28  is made from a textile, such as cotton, nylon, polyester, a polyether-polyurea copolymer, or a combination of the foregoing. The outer covering includes a first end  29  having an opening  31 . In an embodiment, the opening  31  is 0.75 inches (19.05 mm) is provided to allow a mandrel to pass therethrough during assembly. In an embodiment, the opening  31  allows the end  32  to exit the outer covering  28  and connect with the initiator device  36 . In another embodiment, the end  32  exits the internal portion of the outer covering through a hole (not shown) near the periphery of the outer covering  28 . The first end  29  and the opening  31  are configured to expand from a first size to a larger second size as the shock tube coils are inserted into the outer covering  28 . The outer covering  28  further includes a second end  35  that includes the neck portion  26 . 
     The neck portion  26  includes an opening  40 . The neck portion  26  and opening  40  are configured to expand from a first size to a larger second size to allow the shock tube coils  22  to be inserted into the outer covering  28 . After the shock tube coils  22  are inserted, the neck portion  26  and opening  40  return to the first size to retain the shock tube coils  22  within the outer covering  28 . In an embodiment, the second end  35  is shaped like the first end  29  and does not include a neck portion  26 . In an embodiment, the weave of the textile material of the outer covering  28  is configured to be elastic and to automatically reduces in size to the first size after the shock tube coils  22  are inserted. In an embodiment, the neck portion includes a section that extends about the circumference of the neck portion and is elastic, but stiffer, than the surrounding material. In another embodiment, an external elastic member  41  ( FIG. 4 ) is placed around the neck portion  26  after the shock tube coils  22  have been inserted. 
     In an embodiment, the outer covering  28  is sized to provide a compression fit on the shock tube coils  22 . In an embodiment, the outer covering  28  is formed from a single piece textile material. In another embodiment, the outer covering  28  may be formed by multiple components. The multiple components may be separate, integral, or coupled together. In an embodiment, the outer covering  28  is sized to form a compression fit over a 5-inch (127 mm) long×2¾ inch (70 mm) diameter cylinder. It should be appreciated that the cylinder may be larger or smaller. In an embodiment, the outer covering  28  may be formed from any suitable material that maintains a compression fit when exposed to a temperature range of +160 F to −60 F, including in some embodiment one or more of after temperature cycling, after a 10-foot drop, or after being submerged in water. In an embodiment, the material of the outer covering  28  is selected to provide a predetermined sound level when the shock tube coil is being removed during operation. 
     As noted, the detonator  34  is operably connected to the inner end  30  of the coiled shock tube  22 . The detonator  34  may be a device made in accordance with U.S. Pat. No. 6,272,996, the contents of which are incorporated herein by reference. Also, the detonator  34  may be positioned inside the coil  22  for reducing the volume of the resulting package  20 . The igniter  36  is operably connected to the outer end  32  of the tubing  22 , and is held in place by a suitable means, such as an adhesive, an elastic member or a strap for example. The igniter  36  may be a device constructed in accordance with U.S. Pat. No. 6,272,996. Alternatively, the coreless-coil shock tubing package  20  may be provided without a detonator or igniter, in which case these or similar devices would be connected to the coil  22  by a user in the field or otherwise. The igniter and detonator are sometimes collectively referred to herein as “shock tube devices,” by which it is meant a device either for actuating a shock tube or being acted upon by a shock tube signal. 
     As noted above, the shock tubing is provided as a “bundle,” which refers generally to configurations where a length of shock tubing is wound in a compact manner or otherwise compactly arranged. Thus, the shock tubing bundle may be in the form of a coil, or, e.g., it could comprise successive short lengths of the tubing folded back over on one another. The bundle does not have to be cylindrical in overall shape, and could be other shapes. Thus, one embodiment may be characterized as packaged shock tubing comprising a bundle consisting of a compactly arranged length of shock tubing (e.g., no spool or other support) and a flexible or elastic outer covering that maintains the length of shock tubing in a bundled manner, e.g., in a compact arrangement. 
     Alternatively, the detonator  34  is attached to the inner end  30  of the tubing  22  and inserted into the opening provided at one end of the coil  22 . Also, the igniter  36  may be attached to the outer end  32  of the tubing  22  and alternatively retained by a shrink-wrap layer or covering instead of via the strap, elastic member or adhesive. 
     As should be appreciated, instead of tucking in whichever device is attached to the inner tubing end, such device can be left on the outside of the coil and removably secured to, e.g., the end of the coil. Also, for use in certain applications, instead of attaching a detonator  34  to the inner end  30  of the tubing  22  and an igniter  36  to the outer end  32  of the tubing  22 , the igniter may be attached to the inner end and the detonator to the outer end. In this configuration, the detonator and coil would remain with the explosive device while the igniter is moved away from both. It might also be the case that the igniter would remain stationary (e.g., held by a soldier or other user) while the coil and detonator are moved in a direction of interest. 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value. 
     Additionally, the term “exemplary” is used herein to mean “serving as an example, instance or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms “at least one” and “one or more” are understood to include any integer number greater than or equal to one, i.e. one, two, three, four, etc. The terms “a plurality” are understood to include any integer number greater than or equal to two, i.e. two, three, four, five, etc. The term “connection” can include an indirect “connection” and a direct “connection”. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the disclosure is provided in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that the exemplary embodiment(s) may include only some of the described exemplary aspects. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.