Abstract:
A method of cutting a fiber optic cable having an optical fiber surrounded by at least one protective layer comprises providing a cutting tool having opposingly directed blunt surfaces and opposingly directed sharp surfaces. The cutting tool is movable between an opened position and a closed position. This method also comprises the steps of positioning the fiber optic cable between the opposingly directed blunt surfaces and moving the cutting tool toward the closed position sufficiently to crush the optical fiber without cutting through the protective layer. The method further comprises the steps of moving the cutting tool toward the opened position sufficiently to release the fiber optic cable from between the blunt surfaces, positioning the fiber optic cable between the opposingly directed sharp surfaces and moving the cutting tool toward the closed position sufficiently to cut through the protective layer.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to hand tools for cutting cables, and, more particularly, to a hand tool for cutting a fiber optic cable.  
         [0002]     A fiber optic cable typically comprises an optical fiber concentrically surrounded by a series of protective layers. The optical fiber is formed of a hard and brittle material, such-as glass, that provides a path for optical signals to travel along. The optical fiber is surrounded by a layer of strengthening fibers, such as KEVLAR, to provide strength to the fiber optic cable for pulling the fiber optic cable through a conduit. An outer layer of a polymeric material, such as PVC, surrounds the layer of strengthening fibers. The outer layer of polymeric material provides the optical fiber with additional protection from damages or nicks and dampens any shock.  
         [0003]     Hand-held cutting tools having sharp blade edges exist for cutting cables, including those cables comprising KEVLAR. However, should such cutting tools be sued, to cut fiber optic cables, the cutting tools will not be capable of repeated usage. The optical fiber of the fiber optic cable is formed of a hard material. Cutting through the hard optical fiber dulls the blade of the cutting tool prematurely.  
         [0004]     Therefore, a need exists for a hand tool for cutting fiber optic cable with the capability of repeated usage.  
       SUMMARY OF THE INVENTION  
       [0005]     This invention relates to a hand-held cutting tool for cutting a fiber optic cable having an optical fiber surrounded by at least one protective layer. The hand-held cutting tool comprises a first cutting member and a second cutting member. The first cutting member is attached to the second cutting member allowing for movement between an opened position and a closed position. The first cutting member has a blunt surface and a sharp surface. The second cutting member has a blunt surface and a sharp surface. The blunt surface of the first cutting member and the blunt surface of the second cutting member are capable of crushing the optical fiber without cutting through the protective layer. The sharp surface of the first cutting member and the sharp surface of the second cutting member are capable of cutting through the protective layer. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a front view of a hand-held cutting tool of the first embodiment;  
         [0007]      FIG. 2  is a front view of a hand-held cutting tool of the second embodiment; and  
         [0008]      FIG. 3  is an enlarged perspective view of the cutting edge of the hand-held cutting tools of  FIGS. 1 and 2 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0009]     The hand-held cutting tool of the first embodiment of the present invention for cutting a fiber optic cable is illustrated in  FIG. 1 . The first embodiment of a hand-held cutting tool is a scissor-type cutter. The cutting tool  10  of the first embodiment comprises a first cutting member  12 , a second cutting member  14  and a pin  16  for pivotably connecting the first cutting member  12  to the second cutting member  14 .  
         [0010]     Each cutting member  12  and  14  has a pivot hole  18  and  20  defined therein for attaching the cutting members  12  and  14  to the pin  16 . Each cutting member  12  and  14  further has a handle  22  and  24  formed at one end of the cutting member  12  and  14  and a cutting edge  26  and  28  formed at the other end of the cutting member  12  and  14 . The handles  22  and  24  are approximately oval shaped, having approximately oval-shaped openings  30  and  32  defined therein for the user to insert his or her fingers into the handles  22  and  24 . The handles  22  and  24  can be further covered with a polymeric material for easier grip by the user.  
         [0011]     The cutting edge  26  and  28  of each cutting member  12  and  14  is located at one edge of the cutting member  12  and  14 , such that upon the cutting members  12  and  14  being pivotably attached, the cutting edge  26  or  28  of one cutting member  12  or  14  is directed toward the cutting edge  28  or  26  of the other cutting member  14  or  12 . As shown in detail in  FIG. 3 , each cutting edge  26  and  28  has a blunt surface  34  and  36  located radially outwardly of the pivot hole  18  and  20  and a sharp surface  38  and  40  located radially outwardly of the blunt surface  34  and  36 . Since greater cutting force can be applied at the radially inwardly portion of the cutting edge, it is desirable for the blunt surfaces  34  and  36  to be radially inwardly of the sharp surfaces  38  and  40 ; thus, allowing the blunt surfaces  34  and  36  to generate greater cutting force to crush the optical fiber. With the blunt surfaces  34  and  36  of both cutting members  12  and  14  radially inwardly of the sharp surfaces  38  and  40  and of approximately the same length, the blunt surface  34  of the first cutting member  12  is opposingly directed toward the blunt surface  36  of the second cutting member  14  and the sharp surface  38  of the first cutting member  12  is opposingly directed toward the sharp surface  40  of the second cutting member  14 . Although not necessary, it is also desirable for the sharp surfaces  38  and  40  to be serrated. The serration allows the sharp surfaces  38  and  40  to better grip the fiber optic cable, preventing the fiber optic cable from sliding radially outwardly upon closing the cutting tool  10 . To allow the sharp surfaces to remain sharp after repeated usage, the sharp surfaces  38  and  40  can be chrome plated to increase the hardness of the sharp surfaces.  
         [0012]     The first embodiment of a hand-held cutting tool  10  functions as follows. The first cutting member  12  and the second cutting member  14  are pivotably connected by a pin  16  allowing the user to pivotably open the hand-held cutting tool  10  and to pivotably close the hand-held cutting tool  10 . The closing movement of the hand-held cutting tool  10  causes the cutting edges  26  and  28  of the cutting members  12  and  14  to move toward each other. To cut a fiber optic cable comprising an optical fiber concentrically surrounded by a layer of KEVLAR strengthening fibers and an outer layer of PVC surrounding the layer of KEVLAR fibers, the user of the cutting tool  10  first inserts the fiber optic cable between the opposingly directed blunt surfaces  34  and  36  and then closes the cutting tool  10 . The closing movement of the cutting tool  10  crushes the optical fiber and cuts a portion of the PVC layer. The user then opens the cutting tool  10  and inserts the fiber optic cable between the sharp surfaces  38  and  40  such that the cut portion of the PVC layer is located directly inwardly of the sharp surfaces  38  and  40  of the cutting tool  10 . The user then closes the cutting tool  10  to cut through the KEVLAR fibers and the PVC layer.  
         [0013]     The hand-held cutting tool of the second embodiment of the present invention for cutting a fiber optic cable is illustrated in  FIG. 2 . The cutting tool  50  of the second embodiment is similar to the cutting tool  10  of the first embodiment, but includes a spring for biasing the cutting tool of the second embodiment toward an opened position. The cutting tool of the second embodiment comprises a first cutting member  52 , a second cutting member  54 , a pin  56  and a coil spring  58 .  
         [0014]     Each cutting member  52  and  54  has a pivot hole  60  and  62  defined therein for attaching the cutting members  52  and  54  to the pin  56 . Each cutting member  52  and  54  further has a handle  64  and  66  formed at one end of the cutting member  52  and  54  and a cutting edge  26  and  28  formed at the other end of the cutting member  52  and  54 . The handles  64  and  66  have approximately straight outer surfaces  72  and  73  allowing the user to comfortably grip the outer surfaces  72  and  73  of the handles  64  and  66 . Located radially outwardly of the pivot holes  60  and  62  toward the direction of the handles  64  and  66  and directed circumferentially inwardly are a set of spring retention protrusions  74  and  76 . The coil spring  58  is situated and retained between the spring retention protrusions  74  and  76 . The coil spring  58  causes the cutting members  52  and  54  to spring outwardly; therefore, biasing the cutting tool  50  toward an opened position.  
         [0015]     The cutting edge  26  and  28  of each cutting member  52  and  54  is located at one edge of the cutting member  52  and  54 , such that upon the cutting members  52  and  54  being pivotably attached, the cutting edge  26  or  28  of one cutting member  52  or  54  is directed toward the cutting edge  28  or  26  of the other cutting member  54  or  52 . As shown in detail in  FIG. 3 , each cutting edge  26  and  28  has a blunt surface  34  and  36  located radially outwardly of the pivot hole  60  and  62  and a sharp surface  38  and  40  located radially outwardly of the blunt surface  34  and  36 . Since greater cutting force can be applied at the radially inwardly portion of the cutting edge, it is desirable for the blunt surfaces  34  and  36  to be radially inwardly of the sharp surfaces  38  and  40 ; thus, allowing the blunt surfaces  34  and  36  to generate greater cutting force to crush the optical fiber. With the blunt surfaces  34  and  36  of both cutting members  52  and  54  radially inwardly of the sharp surfaces  38  and  40  and of approximately the same length, the blunt surface  34  of the first cutting member  52  is opposingly directed toward the blunt surface  36  of the second cutting member  54  and the sharp surface  38  of the first cutting member  52  is opposingly directed toward the sharp surface  40  of the second cutting member  54 . Although not necessary, it is also desirable for the sharp surfaces  38  and  40  to be serrated. The serration allows the sharp surfaces  38  and  40  to better grip the fiber optic cable, preventing the fiber optic cable from sliding radially outwardly upon closing the cutting tool  50 . To allow the sharp surfaces to remain sharp after repeated usage, the sharp surfaces  38  and  40  can be chrome plated to increase the hardness of the sharp surfaces.  
         [0016]     The second embodiment of a hand-held cutting tool  50  functions as follows. The first cutting member  52  and the second cutting member  54  are pivotably connected by a pin  56  allowing the user to pivotably open the hand-held cutting tool  50  and to pivotably close the hand-held cutting tool  50 . The closing movement of the hand-held cutting tool  50  causes the cutting edges  26  and  28  of the cutting members  52  and  54  to move toward each other. To cut a fiber optic cable comprising an optical fiber concentrically surrounded by a layer of KEVLAR strengthening fibers and an outer layer of PVC surrounding the layer of KEVLAR fibers, the user of the cutting tool  50  first inserts the fiber optic cable between the opposingly directed blunt surfaces  34  and  36  and then closes the cutting tool  50 . The closing movement of the cutting tool  50  crushes the optical fiber and cuts a portion of the PVC layer. The user then opens the cutting tool  50  and inserts the fiber optic cable between the sharp surfaces  38  and  40  such that the cut portion of the PVC layer is located directly inwardly of the sharp surfaces- 38  and  40  of the cutting tool  50 . The user then closes the cutting tool  50  to cut through the KEVLAR fibers and the PVC layer.  
         [0017]     Various features of the present invention have been described with reference to the embodiments shown and described. It should be understood, however, that modifications may be made without departing from the spirit and scope of the invention as represented by the following claims.