Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to tools for attaching connectors to coaxial cables by compressing the connector in a direction parallel to the axis of the cable. More specifically, the present invention relates to axial compression tools capable of attaching different sizes of axial compression connectors to cable of correspondingly different diameters. 
     2. Description of Related Art 
     Coaxial cable is widely used to carry radio and television signals, digital data and the like. A major user of coaxial cable is the cable television industry, which uses coaxial cable to carry the signal from a central location to each subscriber. 
     To make the many connections required for the cable television network requires the installation of numerous coaxial cable connectors. To avoid any interruption in service, it is critical that the connectors be applied properly. Many problems with poor signal quality that require expensive service calls are the result of a connector that was initially installed incorrectly. 
     Coaxial cable connectors come in a variety of designs, and are attached in a correspondingly wide variety of ways with various tools. However, an increasingly popular connector design is secured to the prepared end of the coaxial cable by axially compressing the connector, i.e. by compressing the connector in a direction that is parallel to the longitudinal axis of the coaxial cable. 
     Connectors that are applied this way are available for different cable diameters and have heretofore required different tools for compressing them. U.S. Pat. No. 5,934,137 owned by the assignee of this application shows a widely used axial compression assembly tool, capable of rapid and reliable operation. However, that tool, like other competing designs, is intended to handle only a single connector size. Typically, an installer will carry one tool for attaching connectors to large diameter cable of the type used to distribute the signal from a central point to a neighborhood, and a second tool for attaching smaller connectors on smaller diameter cable used at each drop point to bring the signal into the subscriber&#39;s home. 
     The present tool addresses the industry desire to reduce the number of cable installation tools that the installer must carry. 
     Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a compression assembly tool for axially compressing at least two different sizes of electrical connectors onto coaxial cables. 
     It is another object of the present invention to provide a compression assembly tool which allows the cable and compressed connector to be easily removed from the tool after the connector is compressed. 
     A further object of the invention is to provide a compression tool which maintains the axis of the coaxial cable in accurate alignment with the axis of the plunger. 
     It is yet another object of the present invention to provide a compression tool which is easy to use and which opens automatically, but which can be stored in the closed position. 
     A further object of the present invention is to provide a compression tool which can be easily adjusted. 
     SUMMARY OF THE INVENTION 
     The above and other objects and advantages, which will be apparent to those skilled in the art, are achieved in the present invention which is directed to, in a first aspect, a compression assembly tool for attaching first and second connectors of different sizes to the ends of corresponding first and second different cables. The compression assembly tool includes a body having an open portion defining a compression region for receiving the connectors when they are being attached to their corresponding cables. 
     A lever handle is pivotally attached to the body and drives a plunger in a longitudinal sliding motion relative to the body between an extended position and a retracted position. In the extended position the plunger axially compresses a connector placed into the compression region. In the retracted position the plunger moves out of the way and the compressed connector can be removed from the compression region. 
     The tool has at least two pairs of split base supports located at different distances from the plunger to accommodate different connectors. A first pair of split base supports is located a first distance from the plunger when the plunger is in the extended position. The first split base supports pivot on the body between an open position and a closed position and each of the first split base supports has an annular bearing surface of a first diameter corresponding to the diameter of the first cable. 
     A second pair of split base supports is located a second distance from the plunger when the plunger is in the extended position. The second distance is greater than the first distance to accommodate the length of the second longer connector. The second split base supports are also pivotally attached to the body for motion between an open position and a closed position. Each of the second split base supports has an annular bearing surface of a second diameter corresponding to the second cable. The first split base supports open sufficiently to move out of the way and accommodate the diameter of the second connector when the larger second connector is being compressed. 
     First and second springs operate to urge the first and second split base supports towards the closed position. The annular bearing surfaces of the first split base supports encircle the first cable when they are closed. In the closed position the first pair of split base supports provide annular bearing support for the end of the first connector opposite the plunger during compression. The annular bearing surfaces of the first split base supports allow the first cable to be removed when the first split base supports are in the open position. The annular bearing surfaces of the second split base supports operate in the same way to encircle the second cable when the second split base supports are in the closed position and provide annular bearing support for the back end of the second connector. 
     In another aspect of the compression assembly tool, at least one of the first split base supports and at least one of the second split base supports include a stop surface that contacts the body as the split base supports close. This brings the first and second split base supports into axial alignment with the plunger when the split base supports are closed. In the preferred design, all of the split base supports are identical, except for the diameter of the annular bearing surfaces, and all include a stop surface of this type. 
     The plunger is preferably driven by a link and includes a removable plunger tip that is threaded into the plunger. This allows the plunger tip to be longitudinally adjusted by rotating it relative to the plunger to adjust the distance between the plunger and the split bases and thereby adjust the amount by which the connectors are compressed. When a threaded adjustable plunger tip is used, a locking screw is provided to lock the plunger tip against rotation. The locking screw threads transversely into an end of the plunger to lock the plunger tip against rotation. 
     In yet another aspect of the invention, the compression assembly tool uses an O-frame to provide a light, but strong body structure. In still another aspect of the invention both of the pairs of first and second split base supports are pivotally attached to the body via a common pivot. The handle is provided with a handle spring mounted between the body and the lever handle for urging the lever handle away from the body. A releasable handle lock holds the lever handle towards the body when the tool is not in use. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a side elevational view of the compression assembly tool of the present invention, partly shown in section. Two of the four split bases have been pulled out and rotated to appear in front elevational view, and leader lines have been added to indicate where the two split bases are normally installed. 
     FIG. 2 is a top plan view of the compression assembly tool in FIG.  1 . 
     FIG. 3 is a front elevational view of the compression assembly tool of the invention showing all the split bases in the closed position. 
     FIG. 4 is a front elevational view of the compression assembly tool of the invention showing the inner first pair of split bases in the closed position and the outer second pair of split bases in the open position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In describing the preferred embodiment of the present invention, reference will be made herein to FIGS. 1-4 of the drawings in which like numerals refer to like features of the invention. 
     Referring to FIG. 1, the compression assembly tool of the present invention comprises a lever handle  10  connected to a link  12  driving a plunger  14 . The lever handle  10  is formed as a pair of side plates  10   a  and  10   b  with the link  12  pivoting partially therebetween. The lever handle  10  is pivotally attached to a body  16  via pivot  18 . A torsion spring  20  acts between the body  16  and a pin  22  extending between the side plates  10   a ,  10   b  to urge the lever handle away from the body  16  when it is not restrained. 
     FIG. 1 shows the handle being held close to the body with the plunger  14  in the extended position. It is retained in this position by means of a releasable handle lock formed by bail wire  24 . The bail wire  24  is mounted to the body via retainer  26  and screw  28  which allow it to rotate and unlatch the handle to pivot away from the body. 
     The tool body  16  includes an O-frame portion generally indicated with reference no.  30  which defines a compression region  32 . As the handle  10  pivots around pivot  18  away from the body, link  12  pivots on pivots  34  and  36  and draws the plunger  14  to the retracted position (toward the right in FIG.  1 ). As the handle closes, link  12  drives the plunger  14  to the extended position (toward the left in FIG. 1) and compresses a connector located in the compression region. 
     The O-frame portion  30  of the body  16  is substantially solid along the right side. A bore  38  extends through this solid portion, and plunger  14  slides within this bore. The bore  38  maintains the plunger in constant axial alignment as it moves between the extended and retracted positions. The body is also solid on the lower half of the O-frame in the vicinity of bail retaining member  26  and screw  28 . However, as can be seen in FIGS. 3 and 4, the O-frame is divided into two opposed sidewalls  42 ,  43  and is open along the entire left upper quadrant indicated with reference no.  40 . This allows the coaxial cable and connector to be inserted into the compression region  32  between the sidewalls  42 ,  43 . 
     With the lever handle  10  moved away from the body, and the plunger  14  in the retracted position, a cable and connector can be placed into the compression region  32  by inserting it between opposed sidewalls  42 ,  43 . The tool is adapted to accept two different sizes of connectors. A smaller connector is attached to a smaller diameter cable by compressing the connector axially against a first split base formed by a pair of split base supports  44 ,  45 . The first pair of split base supports  44 ,  45  surround the smaller diameter cable and support the back end of the smaller connector against the axial compression force. A larger connector can be attached to a larger diameter cable by compressing the connector axially against a second split base formed by a second pair of split base supports  46 ,  47  located farther from the plunger  14  than the first split base. 
     All of the split base supports pivot around pivot  48  between open and closed positions. FIG. 3 shows both pairs of split base supports in the closed position. FIG. 4 shows the first pair of split base supports  44 ,  45  in the closed position and the second pair of split base supports  46 ,  47  in the open position. 
     The first pair of split base supports  44  and  45  are identical to each other and need not be made in different right and left versions. The second split base supports  46  and  47  are also identical to each other. As can be seen in the pullout views of the first and second split base supports  45  and  47  in FIG. 1, the first and second split base supports differ from each other only by the diameter of the annular bearing portions  51  and  53 . 
     In order to compress the smaller connector, the smaller connector is first positioned on the end of the smaller cable. The smaller connector is then placed into the compression region  32 . Both the first and second split bases swing open as the cable is pushed between the pairs of split base supports. The split base supports then close to encircle the smaller diameter cable. 
     Annular bearing portions  50 ,  51  are located on the inner perimeter of the first pair of split base supports  44 ,  45 . Annular bearing portions  52 ,  53  are located on the inner perimeter of the second pair of split base supports  46 ,  47 . The diameter D 1  of the opening formed by the bearing portions  50 ,  51  when the first pair of split base supports  44 ,  45  are in the closed position is sufficiently large to accept the smaller diameter coaxial cable, but is smaller than the diameter of the back end of the smaller connector to be compressed. 
     The diameter of the opening D2 formed by the bearing portions  52 ,  53  when the second pair of split base supports  46 ,  47  are in the closed position is sufficiently large to accept the larger diameter coaxial cable, but is smaller than the diameter of the back end of the larger connector to be compressed. When the larger diameter connector is to be compressed, the first pair of split base supports  44 ,  45  swing to the open position, and that position provides sufficient clearance for the larger connector to be placed into position in coaxial alignment with the plunger  14 . 
     As the handle is squeezed toward the body, the plunger  14  moves axially towards the first and second split bases. When the smaller connector is in position it is supported at the back end by the first pair of split base supports and this axial motion of the plunger compresses the smaller connector. When the larger connector is in position it is supported at the back end by the second pair of split base supports and this axial motion of the plunger compresses the larger connector. The second split base plays no part when a smaller connector is being compressed and the first split base plays no part when a larger connector is being compressed. 
     The split base supports  44 - 47  are supported by the O-frame and particularly by the sidewalls  42 ,  43 . The thickness of the solid lower portion of the O-frame in the vicinity of element  26 , can be reduced as compared to prior art devices which do not include the O-frame design and which do not include the sidewalls  42 ,  43  which stiffen the O-frame against any distortion during the compression cycle. This allows the weight of the tool to be reduced without compromising rigidity and also allows a reduction in material cost. 
     To ensure that the distance between the plunger  14  and the plane defined by the split bases is correct, the plunger  14  is provided with an adjustable plunger tip  54  which is threadedly engaged via threads  56  into the end of plunger  14 . A locking screw  58  allows the plunger tip  54  to be locked into position. A locking pad formed of a resilient material, such as plastic, is positioned in the threaded bore between the tip of the locking screw and the threads  56  of plunger tip  54 . The locking pad allows locking screw  58  to exert sufficient force against threads  56  to prevent them from turning while also protecting them from damage. 
     The locking screw  58  is preferably an Allen screw adjustable by an Allen wrench, and plunger tip  54  is preferably adjustable by inserting an Allen wrench along its axis into the head of the plunger tip. The plunger tip can then be rotated to adjust its position relative to the plunger  14 . The hexagonal opening for the Allen wrench also acts to receive the center conductor of a coaxial cable during the compression operation. The plunger tip  54  may be completely unthreaded and removed or replaced. FIG. 2 shows the tool from above with the plunger tip removed. 
     A gage block may be used to set the distance between the plunger tip  54  and the plane of the first split base. The distance between the plane of the first split base and the second split base is set by the design of the tool and need not be adjusted. Accordingly, a single adjustment for wear automatically makes the necessary adjustment for all sizes of connectors to be compressed by the tool. 
     The locking screw  58  is threaded into an enlarged end  76  in plunger  14 . This enlarged end provides material for the threads holding locking screw  58 , and also acts to prevent the plunger  14  from moving too far to the right in the retracted position. In some prior art devices lacking this feature, the handles can be inadvertently locked open when they are opened too far, causing the link between the handles and the plunger to move over center. Such over center locking cannot occur in this design. 
     The first split base supports  44 ,  45  include corresponding push surfaces  80 ,  81 . When the push surfaces are squeezed together towards the sidewalls of the body, a spring  67  (see FIG.  1 ), located between the split base supports is compressed and the first split base supports  44 ,  45  pivot from the closed position to the open position. The second split base supports  46 ,  47  include corresponding push surfaces  82 ,  83 . These operate in the same way to compress spring  66  and open the second pair of split base supports  46 ,  47  so that a cable can easily be inserted. 
     The convenience of this system of split bases allows springs  66  and  67  to be relatively strong, which is advantageous in securely holding the cable and the attached connector in the correct aligned position. 
     Another feature provided by the split base supports is positive alignment of the axis of the opening formed by bearing surfaces  50 ,  51  and  52 ,  53  with the centerline of the plunger  14 . As can be seen best in FIG. 2, The first pair of split base supports  44 ,  45  include corresponding stop surfaces  84 ,  85  at their upper ends. The stop surfaces  84 ,  85  are wider than the slot  88  within which the split base supports pivot. The second pair of split base supports  46 ,  47  also have stop surfaces  86 ,  87  at their upper ends that are wider than the slot  88  within which the second pair of split base supports pivot. 
     In the preferred design, the stop surfaces  84 - 87  prevent the split base supports from pivoting into slots  88 ,  89 . Springs  66 ,  67  can be relatively strong and the dimensions of the split base supports are such that stop surfaces  84 - 87  are flush with the outer sides of the O-frame (as shown in FIGS. 2 and 3) just as the split base supports reach the closed position. This design allows the split base supports to exactly self-enter the cable and connector and accurately position the back end of the connector to be compressed. 
     Push surfaces  80 - 83  provide a simple press-to-open design that may be operated with a single hand. The push surfaces  81 ,  83  are close enough that the thumb may be used to simultaneously press down on both push surfaces. The opposing finger can simultaneously operate push surfaces  80 ,  82  to fully open both the first and second split bases. 
     The preferred design shows two pairs of split bases that define support planes at two different distances from the plunger. However, three or even more pairs of split bases may be installed in other embodiments of the invention to accommodate a series of progressively longer connectors. 
     While the present invention has been particularly described, in conjunction with a specific preferred embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present invention.

Technology Category: h