Patent Publication Number: US-7210327-B1

Title: Reduced actuation force compression assembly tool

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to hand 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 hand operated tools that reduce the force the operator of the tool must apply in order to achieve the required axial compression of the connector. 
   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. For a good connection, it is desirable that the tool be able to apply a relatively high level of axial compression force. However, for ease of operation, it is desirable for the actuation force that must be supplied by the operator to be relatively low. 
   Two prior art compression assembly tools are seen in U.S. Pat. Nos. 5,934,137 and 6,820,326 owned by the assignee of this application. In each of these tools, and in other similar tools of the prior art, a plunger is driven by a handle that rotates on a pivot connecting the handle directly to the body of the tool. In the tools referred to above, the rotary motion of the handle is transferred to the plunger through a relatively short link connected between the handle and the plunger. In other designs the handle may include a cam that drives the end of the plunger through sliding contact. 
   In addition to a low actuation force, and a high compression force, the tool must be able to move the plunger sufficiently far to fully compress the connector. Although the tools of the prior art are effective and capable of compressing connectors, it is desired to reduce the actuation force even more. 
   Another object of the present invention is to provide a compression assembly tool for axially compressing at least two different sizes of electrical connectors onto coaxial cables 
   It is yet another object of the present invention to provide a compression assembly tool that can be produced inexpensively. 
   A further object of the invention is to provide a compression tool that maintains the axis of the coaxial cable in accurate alignment with the axis of the plunger. 
   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 a connector to a cable by axially compressing the connector. The compression assembly includes a body having an open portion defining a compression region for receiving the connector, a first pair of split base supports attached to the body at an end of the compression region, the first pair of split base supports defining a split base opening for receiving the cable and a perimeter of the split base opening acting to support an end of the connector as the connector is compressed, a handle, a plunger mounted for longitudinal sliding motion relative to the body, the plunger being driven by the handle between an extended position to axially compress the connector and a retracted position to allow the connector to be removed from the compression region and a swing arm link. The swing arm link is pivotally connected to the body through a first pivot and pivotally connected to the handle through a second pivot. The plunger is pivotally connected to the handle through a third pivot. 
   The first pivot is farther from the second pivot than the third pivot, preferably at least twice as far from the second pivot as the third pivot. The second pivot moves from a position offset from an axial centerline of the plunger to a position substantially on the axial centerline of the plunger as the handle rotates around the third pivot. 
   The swing arm link may be a single link or a pair of opposed swing arm links. The swing arm link includes a first arm section and an angled second arm section, the first pivot connecting the first arm section to the body and the second pivot connecting the second arm section to the handle. 
   The body of the tool includes a pair of opposed body plates separated by a nose block, the nose block including a U-shaped opening for receiving the cable. The first pair of split base supports are pivotally attached to the body through a pair of corresponding base support pivots. The first pair of split base supports preferably include a corresponding pair of split base stops, the split base stops being located on an opposite side of the pivotal attachment to the body from the split base opening for the cable. 
   In another aspect of the invention, the compression assembly tool further includes a spring urging the pair of split base stops apart and into contact with the body, the contact between the body and each split base stop defining a final predetermined location for each split base stop independent of the position of the other split base stop. 
   The handle preferably is formed by first and second handle plates extending outward from a gripping end of the handle and the third pivot extends from the first handle plate through the plunger to the second handle plate. The body of the tool includes a pair of opposed body plates separated by a nose block and a body block, the nose block and body block being located on opposite sides of the compression region, each body plate having a compression region opening defining an O-frame on each side of the compression region. The first pivot is located closer to the split base supports than the second or third pivots. 
   In still another aspect of the invention which produces the desired low actuation force, the plunger has a front contact surface defining a moving plunger contact plane as the plunger moves from the retracted position to the extended position. The first pivot is located on an opposite side of the plunger contact plane from the second and third pivots when the plunger is in the retracted position. 
   The body of the tool includes a pair of opposed body plates separated by a nose block and the nose block includes a pair of split base slots for receiving the split base supports and at least one corresponding pair of split base guides adjacent to the split base slots and extending outward from the nose block and into engagement with the opposed body plates. The first pair of split base supports are pivotally attached to the body through a first pair of corresponding base support pivots and the second pair of split base supports are pivotally attached to the body through a second pair of corresponding base support pivots. 

   
     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 left side elevational view of the compression assembly tool of the present invention, with the central region of the tool shown in section. The handles are closed and the plunger is extended. 
       FIG. 2  is a bottom plan view of the compression assembly tool in  FIG. 1 . 
       FIG. 3  is a cross sectional view of the compression assembly tool of the present invention taken along the central plane of the tool. The tool is shown from the left side and the handles are open with the plunger retracted. 
       FIG. 4  is a front elevational view of the compression assembly tool in  FIG. 1 . 
       FIG. 5  is a detail view of the split base supports showing the spring that biases the split base supports closed, the pivots for the split base supports and the operation of the split base stops that independently bring the split base supports to a desired final position. 
       FIG. 6  is a left side elevational view of a second embodiment of the present invention showing two pairs of split base supports. The handles are closed and the plunger is extended. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
   In describing the preferred embodiment of the present invention, reference will be made herein to  FIGS. 1–6  of the drawings in which like numerals refer to like features of the invention. 
   Referring to  FIGS. 1–3 , the compression assembly tool of the present invention includes a handle  10 , a swing arm link  12  composed of first and second swing arm links  12   a ,  12   b  and a plunger  14  that slides axially between retracted ( FIG. 3 ) and extended ( FIG. 1 ) positions as handle  10  moves between open ( FIG. 3 ) and closed ( FIG. 1 ) positions. 
   The body of the tool  16  is formed by a pair of opposed body plates  18 ,  20  (see  FIG. 2 ), a nose block  22  and a body block  24 . The body plates sandwich the nose and body blocks between them and the complete assembly is held together by rivets. The body plates  18 ,  20  include integral handle extensions  23 ,  25  located on opposite sides of an integral handle extension  26  of the body block  24 . The body block  24  also includes a cylindrical plunger opening that holds the plunger  14  and allows it to slide axially between the retracted position in  FIG. 3  and the extended position in  FIG. 1 . 
   The opposed body plates  18 ,  20  include corresponding compression region openings  30  providing access to the compression region  32  located between the nose block  22  and the body block  24 . The opposed body plates  18 ,  20  and the compression region openings therein form an O-frame design for the tool which is lightweight and structurally rigid. This design supports the nose block and allows the tool to resist the compression force as a connector is compressed between plunger  14  and the opposed pair of split base supports  34 ,  36  (see  FIG. 5 ). 
   The split base supports  34 ,  36  define a split base opening  38  that is slightly larger in diameter than the coaxial cable  48  and slightly smaller in diameter than the base of a connector to be compressed by the tool. The outer perimeter of the split base opening  38  supports the base of the connector during the compression operation while the front of the connector is engaged by the plunger tip  40 . 
   The split base supports  34 ,  36  pivot outward on pivots  42 ,  44  allowing the coaxial cable  48  (see  FIG. 4 ) to be inserted between the split base supports. The nose block  22  includes a U-shaped opening  46  that receives the coaxial cable  48 . The coaxial cable and connector are inserted into the tool from the top, between the body plates  18 ,  20  and down into the U-shaped opening  46  of the nose block  22 . As the cable contacts angled surfaces  50 ,  52  of the split base supports, the split base supports pivot open about pivots  42 ,  44 . 
   Each split base support includes a corresponding split base stop,  54 ,  56 . The split base stop  56  of split base support  36  is located on the opposite side of the pivot  42 . Thus, as the split base support  36  moves to the left in  FIG. 5 , away from the central plane of the tool, the stop  56  moves to the right, towards the central plane of the tool. This pivoting action by the split base supports causes spring  58  to be compressed. As the coaxial cable enters opening  38 , spring  58  presses outward against the split base stops and pushes them back into contact with the body, closing the split base supports and the opening  38  around the coaxial cable. 
   The contact between the body and the split base stops independently defines the correct final position for each split base support to independently bring each split base support to the correct final alignment with the centerline of the tool and coaxial cable. 
   The moving handle  10  is formed by first and second handle plate  60 ,  62  and a handle block  64 . The handle plate  60 ,  62  are located on opposite sides of the handle block  64  and again, rivets are used to hold the assembly together in a manner similar to the assembly formed by the body block, the nose block and the opposed body plates. The handle block, nose block and body block are all preferably made of plastic. 
     FIG. 3  shows the moving handle  10  in the open position with the plunger  14  retracted. Unlike prior art designs, the moving handle  10  of the present invention is not directly supported by the body and does not directly pivot on the body of the tool. Instead, moving handle  10  is supported by the swing arm link  12  and the plunger  14 , both of which move relative to the body. 
   The swing arm link  12  rotates on a first pivot  70  that directly connects the swing arm to the body. The swing arm link  12  is formed by two separate pieces: a first swing arm link  12   a  and a second swing arm link  12   b . The first and second swing arm links  12   a ,  12   b  are connected to the moving handle  10  via a second pivot  72 . The second pivot  72  extends from the first swing arm link  12   a  through the handle plates,  60 ,  62  to the second swing arm link  12   b.    
   The handle plates  60 ,  62  are located inside the opposed swing arm links  12   a ,  12   b  and on opposite sides of the plunger  14 . A third pivot  74  extends from the handle plate  60  through the back of the plunger  14  to the opposed handle plate  62 . 
   The axial motion of the plunger towards the split base supports and the use of a handle to drive the plunger and compress the connector is fundamentally the same as in the prior art compression assembly tools seen in U.S. Pat. Nos. 5,934,137 and 6,820,326. However, the method by which the handle drives the plunger differs significantly in this invention, and that difference allows the present tool to produce a high compression force with a low actuation force. 
   In the present invention, the swing arm link  12  includes a relatively long and straight arm section connected to the body of the tool by the first pivot  70  and a relatively shorter angled arm section connected to the handle with the second pivot  72 . The handle  10  is supported by the two pivots  72 ,  74 , each of which moves relative to the tool body as opposed to prior art designs where the handle pivots on a stationary pivot directly connected to the body. The design shown here with the shaped swing arm link allows the tool to produce a significantly greater compression force while reducing the actuation force that the user must apply to the handle. 
   This benefit is achieved, in part, by locating the first pivot  70  near the front of the tool and using a moving second pivot  72  connected to the handle  10 . The second pivot  72  pivots from an offset position relative to the axis of the plunger  14  (as seen in  FIG. 3 ) to a location behind, and preferably to the far side of the axis of the plunger  14 , as seen in  FIG. 1 . As the handle  10  is rotating around pivot  72 , the pivot  72  is moving around pivot  70  located close to the front of the tool. This double-pivoting action provides the desired high compression force with a low actuation force. 
   As can be seen in  FIG. 3 , with the handles open and the plunger retracted, the first pivot  70  is located ahead of a plane defined by the front of the plunger  14 . Preferably the swing arm link  12  is sufficiently far ahead of the plane defined by the front of the plunger  14  that the axis of the first pivot  70  is also ahead of that plane when the handle is closed as seen in  FIG. 1  with the plunger extended. 
   As the handles are squeezed, the second pivot  72  moves from a position offset from the axial center line of the plunger  14  as seen in  FIG. 3  and rotates around the third pivot  74 . As the plunger  14  moves to the extended position it compresses the connector which is trapped between the plunger and the split base supports  34 ,  36 . 
   As can be seen in  FIGS. 1 and 3 , the first pivot  70  is farther from the second pivot than the third pivot. Preferably, the first pivot is at least twice as far from the second pivot as the third pivot. The first pivot is located closer to the split base supports than the second or third pivots. 
   The split base supports  34 ,  36  are held in slots in the nose block  22 . The nose block  22  is provided with at least one pair of split base guides  90 ,  92  that extend outward from the nose block through split base openings  94  in the body plates. In the preferred design illustrated, the nose block  22  includes a second pair of split base guides  96 ,  98  such that each split base support slides between split base guides. Split base support  34  slides between split base guides  92 ,  98  and split base support  36  slides between guides  90 ,  96 . The split base guides extend outward through a corresponding split base opening in the body plate and serve to keep the split base supports accurately in the desired plane and transfer the force to the body plates as the connector is compressed. 
   The split base guides are all formed as an integral piece of the plastic molded nose block  22 . Because the split base guides extend outward through openings in the body plates, they help to hold the body together and to transfer compression forces from the nose block to the body plates. 
   The tool shown in  FIGS. 1–5  uses a single pair of split base supports and a plunger to compress a single type of connector corresponding to the tool shown in U.S. Pat. No. 5,934,137. The present invention includes a second embodiment shown in  FIG. 6  in which a second pair of split base supports  100  are included. The body block and body plates in this embodiment are extended. The body block includes a second pair of split base guides  102 ,  104 . In other respects the tool operates in essentially the same way as the tool described above. 
   The operation of a tool with two split base supports is described in U.S. Pat. No. 6,820,326 owned by the assignee of this application. The two split base supports allow a single tool to compress two different types of connectors of two different lengths. When compressing the longer connector, split base supports  100  are active (closed to support the back of the longer connector) and split base supports  36 ,  34  are open and out of the way. 
   The second embodiment described above shows two pairs of split base supports 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 or shorter 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.