Abstract:
A cable stripper of the type typically used by an operator to remove the outer insulation layer from a coaxial cable having a ridged outer conductor such as that typically used in the telecommunications industry. The cable stripper includes unique stop devices that actually engage the stripped outer conductor so as to prevent removal of more than a predetermined length of the outer insulation and so as to present the distal end of the stripped cable for trimming so that the cable is properly prepared for use and installation.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cable stripper of the type used to remove the outer insulation layer of a coaxial cable such as that typically used in the telecommunications industry, and for trimming the stripped distal end of the cable, thereby preparing the stripped cabled for use. The cable stripper of this invention is particularly characterized by its construction including at least one cable stop operatively mounted on the stripper for positively engaging the outer conductor, once the insulation has been removed, so as to provide a stripped cabled segment of predetermined length such that connectors and/or splices applied to the stripped cable distal end will fit properly to ensure proper functionality of the cable. 
     2. Description of the Prior Art 
     In the telecommunications industry, relatively large diameter coaxial cables are typically used for transmitting signals from antenna towers to switching equipment. These cables have an outer insulation layer, an outer conductor that is typically formed from copper and has a ridged surface, a layer of foam-type insulation, and an inner conductor, also typically formed from copper. In order to make connections to the cable, it is necessary to remove the outer insulation, and to trim the stripped distal end of the cable. This stripping and trimming operation is critical in at least three regards. First, depending upon the connection being made, a very precise segment of the outer insulation must be removed so as to provide an exposed outer conductor at the cable&#39;s distal end having a predetermined longitudinal dimension. Second, the exposed surface of the outer conductor must not be scratched, bent, nor otherwise marred, for this could result in an improper, non-functional connection being made. Third, the distal end of the stripped cable must be trimmed so that it defines a plane that is substantially normal with respect to the axis of the cable to ensure proper, functional attachment of connecting devices. 
     While a wide variety of cable stripping devices are known in the prior art, the majority of such prior art devices are constructed merely to remove an outer insulation layer from a conductor. This is true with regard to single conductors and coaxial conductors. Such prior art devices sometimes remove the outer insulation layer by making a longitudinal slit, and others dispose a blade tangentially to remove the outer insulation in a spiral as the cutting device is rotated about the conductor. In most prior art devices, if the distal end of the stripped conductor is to be trimmed, it is frequently necessary to reposition either the cutting device or the stripped cable before trimming the distal end. 
     In light of the development of relatively large diameter coaxial cables such as those used in the telecommunications industry and generally described above, cable stripping devices for removing the outer insulation layer and for trimming the stripped distal end have been developed. Such devices basically take the form of a cylinder having a passageway through the axis for insertion of the cable to be stripped. In such prior art devices, the cable first encounters a tangential blade that will remove the outer insulation layer as the device is rotated around the cable. The outer insulation is removed as a spiral, and the stripped cable end advances into the stripper. When sufficient outer insulation has been removed the stripped distal end will encounter a second cutting blade that is disposed to trim the stripped distal end to define a plane that is substantially normal to the longitudinal axis of the stripped cable. However, if the operator of the cable stripper continues to rotate the device, more and more outer insulation will be removed, and a corresponding excess of stripped distal end will also be removed. Obviously, this can, over time, result in significant waste of relatively expensive coaxial cable. 
     The above problem is a result of the fact that prior art devices simply do not provide suitable means for stopping the advancement of cable into the stripper once a predetermined length of the outer insulation layer has been removed. Obviously, the length of exposed outer conductor is predetermined by the distance between the first cutting blade and the second cutting blade. However, there simply is no effective means for stopping the cable stripper once the predetermined segment of outer insulation has been removed. 
     It is therefore apparent that there remains a great need in the art for a cable stripper suitable for use in combination with coaxial cables for removing the outer insulation and for trimming the stripped distal end, and for positively stopping the stripping action once a predetermined segment of outer conductor has been has been exposed. In addition, any such means for stopping further advancement of the cable once the predetermined segment has been exposed must not damage the outer conductor, or subsequent failure of the cable for its intended purpose could occur. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a cable stripper for removing the external or outer layer of insulation on a coaxial cable having a ridged outer conductor and an inner conductor, the two conductors being separated by insulation. The cable stripper further includes means for trimming the stripped cable end to define a plane that is substantially normal to the longitudinal dimension of the stripped cable. The cable stripper of this invention is preferably a substantially cylindrical housing having a central bore for receiving the cable to be stripped. This bore or passageway is dimensioned and configured to receive the cable and a first blade is mounted on the housing in operative communication with the passageway whereby the first blade will remove the outer layer of insulation from the cable as either the stripper is rotated, or the cable is rotated. As stripped cable advances into the passageway, the stripped distal end engages a cable shoulder formed on at least one cable stop that is pivotally attached to the housing, causing the cable stop to pivot outwardly. 
     Disposed at the bottom of this cable stop is a lock tip that necessarily pivots inwardly, toward the stripped cable. Mounted below the cable stop is a retaining member that is biased into engagement with the bottom of its corresponding cable stop. This bearing surface defines a first planer segment that abuts a corresponding stop member bottom surface, and the bearing surface then defines a second angled surface that will engage the backside of its corresponding cable stop when it has pivoted sufficiently to clear the first planer segment. Because the retaining member is normally biased toward its corresponding cable stop bottom surface, as the stop pivots beyond the retaining member first planer segment onto the second angled surface, the biasing action will effectively lock the lock tip into a corresponding groove of the ridged outer conductor. This positively prevents further advancement of the cable into the stripper, resulting in a stripped distal end having a longitudinal dimension defined by the predetermined distance between the first and second blades of the stripper and prevents waste of the conductor. Depending upon the size (diameter) of the cable, a plurality of cable stops and, thus, a corresponding plurality of retaining members may be utilized for preventing further advancement of the cable. 
     The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the preferred construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a top plan view of a preferred embodiment of the cable stripper with portions of the interior detail shown in broken lines. 
     FIG. 2 is a front side elevation of the stripper shown in FIG.  1 . 
     FIG. 3 is a left side elevation of the stripper shown in FIG.  1 . 
     FIG. 4 is a is a bottom plan view, partially in section to show interior detail, of the stripper of FIG.  1 . 
     FIG. 5 is a perspective view of the Stripper shown in FIG.  1 . 
     FIG. 6 is a sectional view taken along line  6 — 6  of FIG.  1 . 
     FIG. 7 is a sectional view similar to that of FIG. 6 with a stripped cable inserted. 
    
    
     Similar reference characters refer to similar parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The cable stripper of this invention is generally indicated as  10  in each of the drawing figures, and generally illustrated in the perspective view of FIG.  5 . Referring to the view of FIG. 5, it can be seen that the preferred embodiment for stripper  10  comprises a generally cylindrical housing, generally indicated as  12 , and having a top end  14  and a bottom end  16 . A handle, or shaft,  18  is attached to housing  12  and extends upwardly from top end  14 . Gripping and turning handle  18  will cause the entire stripper  10  to rotate. It is also to be understood that handle  18  could be engaged by a power tool, or could be modified to include a T-bar such that stripper  10  could be turned manually. Formed along the central axis of housing  12  is a passageway  20 , the partially open top end of which is seen in the view of FIG.  5 . 
     Turning to the sectional views of FIGS. 6 and 7, one can see that passageway  20  is dimensioned and configured for reception of the cable, generally indicated as  22  in the view of FIG.  7 . Cable  22  is of the type typically used in the communications industry and includes an external layer of insulation  24 , a ridged outer conductor  26 , an inner conductor  28 , and insulation  30  disposed between outer conductor  26  and inner conductor  28 . External insulation  24  is typically a plastic material, outer conductor  26  and inner conductor  28  are typically copper, and insulation  30  is typically a foam-type material, such as, for example, styrofoam. As seen in the sectional view of FIG. 7, the ridged configuration of outer conductor  26  provides a plurality of lands  32  and grooves  34  once external insulation  24  has been removed. 
     Turning to the views of FIGS. 3 and 4, stripper  10  further comprises a first blade  36  mounted on housing  10  and including a first blade sharpened edge  38  disposed in communicating relation to passageway  20  such that sharpened edge  38  may engage and remove the external layer of insulation  24  as cable  22  is inserted into stripper  10  and stripper  10  is rotated. First blade  36  may be attached to a portion of housing  12  as by screw  40 . 
     Returning to the perspective view of FIG. 5, stripper  10  further comprises a second blade  42  having a sharpened edge  44  mounted on housing  12  such that second blade sharpened edge  44  is disposed in operative communication with the distal end of cable  22  from which the outer insulation  24  has been stripped. Second blade  42  may be attached as by adjustable set screw  46 . Thus, sharpened edge  44  is operatively mounted so that it may trim the distal ends of outer conductor  26 , inner conductor  28 , and insulation  30  disposed there between so as to provide a planer end of stripped cable  22  that is substantially normal to the longitudinal dimension of cable  22 . 
     With particular regard to the sectional views of FIGS. 6 and 7 and the top and bottom plan views of FIGS. 1 and 4, stripper  10  further comprises a plurality of cable stops, generally indicated as  48  in the views of FIGS. 1 and 4. While three cable stops  48  are shown in this preferred construction for stripper  10 , it is to be understood that one or more will provide functionality. Each of the cable stops  48  comprise a stop member  50  having a top surface  52 , a bottom surface  54 , and a back surface  56 . Each of the stop members  50  is pivotally attached to housing  12  as by pivot pin  58 . Extending outwardly from stop member top surface  52  toward passageway  20  is a cable shoulder  60 . Comparing the views of FIGS. 6 and 7, one can see that cable shoulder  60  extends into passageway  20  such that the distal end of stripped cable  22  engages cable shoulder  60  to pivot it outwardly. Extending outwardly from stop member bottom surface  54  is a lock tip  62 . As clearly seen in the view of FIG. 7, the pivoting action of stop member  50  will cause each of the lock tips  62  to engage a corresponding groove  34  on the exposed surface of ridged outer conductor  26 . This effectively locks cable  22  from further advancement, thereby preventing any further trimming of the stripped cable  22  by second blade  42  and its sharpened edge  44 . It is also to be noted that each of the lock tips  62  are preferably formed from plastic material so that no damage or scarring is caused along the exposed surface of ridged outer conductor  26 . In this preferred embodiment for stripper  10 , lock tips  62  are formed from nylon. 
     Disposed below each of the stop members  50  is a retaining member  64  with each of the retaining members  64  having a bearing surface  66  disposed in abutting relation to corresponding bottom surface  54  of stop member  50 . A biasing means  68  is operatively disposed between bottom end  16  of housing  12  and each of the retaining members  64  such that each of the bearing surfaces  66  normally abut a corresponding bottom surface  54  as best seen in the view FIG.  6 . Referring to the view of FIG. 7, one can see that as the stop members  50  pivot, each of the bottom surfaces  54  move off bearing surface  66  onto angled surface  70  and are held in the position shown in the view of FIG. 7 by the action of biasing means  68 . This effectively locks each of the lock tips  62  into a corresponding groove  34 , as described above. 
     In order to release the stripped cable  22  from stripper  10 , stripper  10  further comprises a reset ring  72 . Reset ring  72  is moveably disposed around housing  12  and attached to each of the retaining members  64  by reset screws  74 . As best seen in the views of FIGS. 2 and 3, portions of housing  12  are relieved to define reset slots  76  whereby the reset ring  72  may be pulled downwardly against the normal action of biasing means  68  to release each of the lock tips  62  from its corresponding groove  34  and reset each of the stop members  50  to the “rest” position illustrated in the view of FIG. 6. A plurality of stop member biasing means which, in this preferred embodiment comprise a top biasing band  80  and a bottom biasing band  82  assist in resetting stop members  50 . Each of the top and bottom biasing bands  80  and  82 , respectively, are preferrably formed from an elastic material such as, for example, rubber O-rings. As shown in the view of FIG. 7, when stop member  50  pivots outwardly a portion of back surface  56  engages the biasing resistance provided by top biasing band  80 . Thus, when reset ring  72  is pulled downwardly to reset stop members  50  to the “rest” position shown in FIG. 6, the action of top biasing band  80  ensures proper repositioning of each of the stop members  50 . Bottom biasing band  82  serves to ensure proper “rest” positioning of the stop members  50 . 
     Finally, it is to be noted that a plurality of pivot pin access ports  78  are provided through housing  12  for the removal of pivot pins  58 , as necessary. 
     While the above detailed description has been given with regard to a preferred construction, it is, of course, to be understood that stripper  12  may be easily modified and adapted to permit use with a variety of cable sizes. Modification of the device by the replacement of stop members  50  and retaining members  64  of different sizes, along with a modification of the distance between sharpened edge  38  and sharpened edge  42  would permit stripping different lengths of external insulation  24  in accord with the requirements of the intended end use of cable  22 . In all instances it is important to note that the exposed surface of ridged outer conductor  26  will not be damaged or marred and that cable  22  will be locked against further advancement into stripper  10 , thereby virtually assuring that cable  22  is properly stripped to ensure its functionality in an operational installation. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and, since certain changes may be made in the above article without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall there between. 
     Now that the invention has been described,