Abstract:
An apparatus for cutting an underwater cable, wire or line is provided. The apparatus includes a body with a lid and a base. A piston is located, within the body, and a piston rod is coupled to the piston. An elongate lever cutting element is pivotally coupled to a distal end of the piston rod and also pivotally coupled to the base. Upon actuation, water is introduced through the lid and into the body, moving the piston and piston rod, which actuates the elongate lever cutting element. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.

Description:
FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT 
   This invention (Navy Case No. 97355) was developed with finds from the United States Department of the Navy. Licensing inquiries may be directed to Office of Research and Technical Applications, Space and Naval Warfare Systems Center, San Diego, Code 2112, San Diego, Calif. 92152; telephone (619) 553-2778; email: T2@spawar.navy.mil. 

   BACKGROUND 
   This invention relates generally to cable cutters. More specifically, but without limitation thereto, this invention relates to an underwater cable cutter that uses water pressure to cut a cable underwater. 
   The design and use of cable cutters for ocean environments has become of increasing importance to marine engineering. Presently, the use of such cutters is desired for all depths of the world&#39;s oceans. Cable cutters are of great interest to the U.S. Navy. One major Navy application is in minesweeping operations. 
   The design and construction of cable cutters fall within a wide area of engineering disciplines. The general method for cable cutting is a mechanical technique usually involving severing a cable or wire placed between an anvil and a cutter. In some cases scissor-like devices are used. Operation of the cable cutter has included direct, hands-on, manipulation by a diver as well as remote operation of a cutter. Mechanical and explosive techniques are common. Generally, such cable cutters have been designed to be expendable in that they are to be used only once and/or are allowed to be lost or destroyed when operated. 
   Originally, cable cutters were designed mostly for cutting simple wire ropes and electrical cables. Modern state-of-the-art electrical cable construction however has resulted in the use of KEVLAR as a strength member. KEVLAR is a tough synthetic fiber that is usually difficult to cut by ordinary scissor mechanisms. Consequently, many new designs for various types of cable cutters have been presented. These generally incorporate powerful anvil/cutter blade mechanisms. 
   Cable cutters designed for use at great ocean depths have been required to be heavy and bulky in order to protect certain pressure sensitive components from high hydrostatic pressures. 
   This is particularly true where hydraulic systems are used to provide a powerful cutting force. Therefore, there remains a need to overcome one or more of the limitations in the above-described art. 
   SUMMARY 
   An underwater cable cutter apparatus (“cable cutter”) comprises an apparatus for cutting a cable, wire or other line located underwater. The apparatus includes a body with a lid and a base. A piston is located within the body, and a piston rod is coupled to the piston. A cutting element is pivotally coupled to a distal end of the piston rod and also pivotally coupled to the base. Upon actuation, water is introduced through the lid and into the body, moving the piston and piston rod and thereby operating the cutting element. The cable, wire or line to be cut is positioned in a cable holder, and the cutting element cuts the cable, wire or line when operated by the piston rod. 
   A feature of the cable cutter is that it is actuated by water pressure. That is, the cable cutter severs cables, wires or other types of lines that are underwater by using only the surrounding water pressure to generate the force required to cut the cable. 
   These and other features and advantages will be appreciated from review of the following Description, along with the accompanying figures in which like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an elevation view of a representative embodiment of the underwater cable cutter described herein; 
       FIG. 2  is a cut away view of the underwater cable cutter of  FIG. 1 ; 
       FIG. 3  is an exploded view of the underwater cable cutter of  FIGS. 1 and 2 ; and 
       FIG. 4  is a perspective view of the underwater cable cutter of  FIGS. 1 ,  2  and  3 . 
   

   It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. The Figures are provided for the purpose of illustrating one or more embodiments with the explicit understanding that they are offered by way of example only and are not intended to limit the scope of the invention. 
   DESCRIPTION 
   Referring now to  FIGS. 1-4 , an underwater cable cutter  10  is illustrated. Underwater cable cutter  10  uses a piston  12 , shown in  FIGS. 2 and 3 , that is connected to a piston rod  14  with a seal  13  located therebetween. These are contained in a body  16  that in one embodiment comprises a hollow cylindrical housing. As shown in  FIGS. 1 and 2 , a portion of piston rod  14  extends out of a base  18 , shown attached to body  16 . Body  16  is originally filled with air such as at sea level pressure. The extending end of piston rod  14  is pivotally attached to a cutting element  20 , which in one embodiment comprises an elongate lever member having a cutting surface at one end. When positioned underwater and actuated, water enters a water chamber  22  (see  FIG. 2 ) and impinges upon piston  12 , thereby translationally moving piston rod  14  and in turn causing elongate lever cutting element  20  to cut a cable  36  ( FIG. 4 ). Cable  36  is held by a cable holder  24  and cable lock  26 . 
   Because the density of water is over 800 times greater than the density of air (at standard temperature and pressure), it will be appreciated that a substantial cutting force can be generated by immersing the cable cutter  10  in only a relatively small depth of water. Besides originally providing body  16  with sea level air pressure, the air located within the interior of the body  16  may be initially eliminated, or substantially eliminated, creating a vacuum, or partial vacuum. Such a low pressure environment can be selected for just that part of cutter  10  identified in the figure as air chamber  28 . Thus an even greater pressure differential can be selected to exist between the interior of the body  16  and the exterior of the body  16 . 
   The cutting process is initiated by removing either an exterior actuator  30  or an interior actuator  32  from lid aperture  34 . An O-ring, D-ring or other suitable sealing element is positioned between the actuators  30 / 32  and lid aperture  34  to seal against water from entering the water chamber  22  when the actuators  30 / 32  are in position. Once actuator  30  or  32  is removed, water flows into water chamber  22  and pushes upon piston  12 . Because the volume on the other side of the piston  12 , shown in  FIG. 2  as air chamber  28 , contains typically air at sea level pressure or less, the force generated by the incoming water moves the piston  12  and its attached piston rod  14  to thereby actuate cutting element  20  and cut cable  36 , shown in  FIG. 4 . It will be appreciated the cable  36  may be a wire rope, electrical cable, or other type of line, wire, or cable. 
   As shown in  FIGS. 2 and 3 , underwater cable cutter  10  is partially constructed of housing or body  16  that includes attached base  18  though which piston rod  14  extends. Body  16  also includes a deployment flange  38  that defines one or more apertures for receiving a coupling element such as a clamp, bracket or other device that may be used to facilitate the lowering and raising of underwater cable cutter  10  into and out of the water. The shape of the flange  38  may, of course, vary as well as the devices and securing means used to raise and lower underwater cable cutter  10  into and out of water. 
   Referring to  FIGS. 1 and 3 , base  18  of underwater cable cutter  10  also includes a sacrificial anode  40 . Anode  40  may be constructed of zinc, as well as of other suitable sacrificial material such as magnesium, for example. The utilization of anode  40  permits the corrosion of other components of underwater cable cutter  10  to be substantially reduced, thereby extending the service life of cutter  10 . 
   Referring now to  FIGS. 2 and 3 , a lid  42  is positioned opposite base  18 . Lid  42 , base  18  and body  16  form a cavity, within which are located piston  12  and piston rod  14 . Lid  42  defines lid aperture  34 , designed to receive exterior actuator  30  or interior actuator  32 . A lid seal  44  is used to impede water from entering the interior of body  16  at this interface. Lid seal  44  may be an O-ring, D-ring or other type of suitable sealing element. A piston seal  46 , which may be an O-ring, D-ring or other type of suitable sealing element, is located within base  18  around piston rod  14 . The piston seal  46  impedes water from entering into the hollow interior of the body  16  when the piston rod  14  is stationary and when piston rod  14  is actuated. Piston  12  is bolted to piston rod  14  by a suitable fastener, such as a threaded bolt, for example. 
   In one embodiment piston  12  is fitted with two sealing rings  48  that may be O-rings, D-rings or other types of sealing elements that impede the passage of water. It will be appreciated that other numbers of sealing rings  48  may be employed. The sealing rings  48  may be the same diameter and thickness, or they may differ in diameter and thickness. 
   A lid retainer  50  secures lid  42  to body  16 . As shown in  FIGS. 1-3 , lid retainer  50  may in one embodiment comprise three curved elements that are bolted or otherwise fastened around body  16  and lid  42 . Of course, lid retainer  50  may comprise less than or more than three elements. In the representative embodiment shown, fasteners  52  are used to secure the lid retainer  50  to the body  16 . Fasteners  52  are also used to secure anode  40  to base  18 , cutting element  20  to piston rod  14 , piston  12  to piston rod  14 , and cutting element  20  to a pivot pin  54 . These fasteners may be bolts or any other types of suitable fastening elements. 
   As shown in  FIGS. 1 and 2 , piston rod  14  is attached to piston  12  ( FIG. 2 ) and to one end of cutting element  20  at cutting element slot  56  ( FIG. 1 ). Cutting element  20  is also attached to base  18  such as by pivot pin  54 . As shown in  FIGS. 1 and 3 , two pin supports  58  extend from base  18  and each include an aperture for pivotally receiving pivot pin  54 . Pin supports  58  may be integral to base  18 , or they may be welded or otherwise affixed to the base. Pivot pin  54  is moveably secured to pin supports  58  by a pin fastener  60 , which may comprise a C-ring, lock washer, or other type suitable device. 
   Pivot pin  54  allows elongate lever cutting element  20  to pivot about pivot pin  54  while remaining attached to base  18 . Cutting element  20  includes a cutting edge or surface  62 , as shown in  FIG. 4 , that is located at the end of cutting element  20  that lies adjacent to pivot pin  54 . Cable holder  24  is also mounted to base  18  and, as shown in  FIGS. 1 and 2 , includes a cable opening-recess  64  for receiving cable  36 . As shown in  FIG. 4 , cable  36 , which may also be a wire or line, is positioned in cable opening  64 . Cable locks  26  are then secured to cable holder  24  by fasteners  52  to thereby capture cable  36  within cable opening  64 . 
   Referring now to  FIGS. 1-3 , water is introduced into water chamber  22 , this chamber being formed by lid  42 , body  16  and piston  12 . This introduction is permitted upon the activation of either exterior actuator  30  or interior actuator  32 , both of which are located in lid aperture  34 . 
   In one embodiment, wherein an exterior actuator  30  is employed, the exterior actuator may be removed via a buoy attached to the actuator by a cable or directly by a cable (neither shown) so that when the actuator  30  is pulled free from lid  42 , water is allowed to pass through lid aperture  34 . Alternatively, in another embodiment, an interior actuator  32  may be employed, this interior actuator also being positioned in lid aperture  34 . An acoustic release, designed to function upon receiving an acoustic signal, may be made integral with interior actuator  32 . Upon receiving a designed acoustic signal, interior actuator  32  separates from lid aperture  34  so that water pressure forces the interior actuator into the interior of body  16 . Consequently, water is allowed to push against piston  12  thereby moving the piston and attached piston rod  14  toward base  18 . It will be appreciated that other methods may be employed to seal, and subsequently un-seal lid aperture  34 . 
   When water is introduced into water chamber  22 , the water pressure forces piston  12  away from lid  42  and towards base  18 , thereby decreasing the size of air chamber  28 . For example, in one embodiment of cable cutter  10 , body  16  may have an internal volume of approximately 43 cubic inches, and the surface area of piston  12  is approximately 10 square inches. It will be appreciated that the internal volume of body  16 , the surface area of piston  12 , and other dimensions of the cable cutter  10  may vary from these example dimensions. 
   When piston  12  is driven by water pressure, cutting element  20  pivots about pivot pin  54  and piston rod  14  pushes the other end of cutting element  20  from base  18  (these actions shown by arrows in  FIG. 1 ). Cutting element slot  56  allows relative movement between piston rod  14  and the elongate lever cutting element  20 . As cutting element  20  pivots about pivot pin  54 , cutting edge  62  moves toward base  18 . This leveraged cutting action thereby cuts cable  36  located in cable opening  64 . Put differently, as water pressure pushes on the piston  12 , the piston rod  14  is also pushed. Rod  14  is attached to cutting element  20  at cutting element slot  56 . As piston rod  14  moves in this fashion, cutting element  20  pivots about pivot pin  54  and thereby moves cutting edge  62  towards base  18 . As cable  36  is located in cable opening  64 , and as elongate lever cutting element  20  rotates, cutting edge  62  cuts the cable. 
   Because water pressure is used as an operating force to cut the cable, the underwater cable cutter disclosed herein is reliable, and circumvents a more complex hydraulic system as well as avoids the inherent complexities of dangerous explosives. Body  16 , base  18 , lid  42 , cutting element  20 , piston  12 , piston rod  14 , lid retainer  50 , cable holder  24 , cable lock  26 , and other components of the underwater cable cutter  10  may be constructed of metal, metal alloys (such as steel and stainless steel), plastics, silicone rubber, and other suitable elements. 
   Thus, it is seen that an apparatus and method for cutting a cable located underwater is provided. While specific embodiments have been described, it is evident that many alternatives, modifications, permutations and variations will become apparent to those of ordinary skill in the art in light of the foregoing description. Obviously, many modifications and variations are possible in light of the above description. It is therefore to be understood that within the scope of the claims the inventions may be practiced otherwise than as has been specifically described.