Abstract:
A tool for installing compression connectors of various sizes and types on the end of a coaxial cable has a base mounting a pair of movable anvils for engaging two different lengths of connectors. The base further incorporates a fixed anvil for engaging a third length of connector. The movable anvils define an aperture which is shaped to permit easy entry and exit of a cable while still applying a suitable retention force to an inserted cable. A connector seating holder is formed in the front of the tool. A slidably mounted plunger cooperates with the anvils to compress a connector. The plunger has a push head and a slide rod. A lock nut is threaded on the push head and is engageable with the slide rod to prevent rotation of the push head.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to a tool for installing compression connectors on the end of coaxial cable. Such connectors come in a variety of styles and sizes. Among the styles are F-type, BNC and RCA connectors. Among the sizes are RG-6, RG-11 and RG-59. Details of the three connector styles are shown in U.S. Pat. No. 7,153,159. Installation of each style of compression connector entails inserting the prepared end of a coaxial cable a predetermined distance into the connector and then compressing the connector to deform a portion of it and lock it onto the cable. Compression tools for performing this function are known. Such tools have a zone which receives a connector pressed onto the end of a coaxial cable. A compressive force then is applied to the ends of the connector to deform the connector and complete the installation. 
         [0002]    One disadvantage of early compression tools is the compression chamber is sized to accept only a single size or type of connector. Several such tools were required in a technician&#39;s toolbox to accommodate all the sizes that might be needed. Some prior art tools addressed this problem by providing multiple, separate inserts or plungers to accommodate different connector sizes. However, this requires the technician to change out the tool parts every time a different size connector is encountered. Time is lost performing the change. Furthermore, this type of multiple component tool still does not remove the need to have separate tools or components for separate sizes of connectors. 
         [0003]    A prior art tool that does accommodate two different connector sizes in a single tool with no removable parts is shown in U.S. Pat. No. 6,820,326. This tool has two pairs of split bases at separate longitudinal locations in the compression chamber. While this allows the tool to be used on two different connector sizes, it introduces problems of its own. Chief among these is the inability to release a finished cable/connector combination without separate manipulation of the split bases. A user typically holds the compression tool in the palm of one hand and the cable/connector in the other hand. The cable/connector is inserted into the compression chamber where the split bases engage the cable and provide the abutment for the back end of the connector. Then the tool handle is squeezed to perform the compression. Now the finished cable is ready for release from the tool but the split bases will not readily release it. Instead the user has to perform an awkward maneuver in which he or she balances the tool in the palm and outer fingers so the thumb and forefinger are available to actuate the split bases to the open position. Alternately, the user might try a similar maneuver with the opposite hand, that is, grasping the cable with a couple fingers while opening the split bases with two other fingers and then pulling one hand away to remove the cable from the tool. Neither of these methods of releasing a finished cable from the tool is convenient. It has also been found that this tool does not work well with RG-11 F-type compression connector. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides a tool for installing compression connectors of various sizes and types on the end of a coaxial cable without the need for multiple tools or components. The tool of the present invention has a pair of movable anvils for engaging two different lengths of connectors and a fixed anvil for engaging a third length of connector. The movable anvils have an aperture which defines a throat that is large enough to permit easy entry and exit of a cable and small enough to apply a suitable retention force so that a cable will not inadvertently come out of or move around in the aperture prior to compression. The anvils each have a pair of movable spring clips with a depression or cutout in an edge thereof such that opposed spring clips define the cable-receiving receptacle. A connector seated at the proper location on the end of the cable is placed between the plunger and face of the anvil with the cable extending through the aperture in the anvil. Then the plunger is actuated to compress the connector and fix it in place on the cable. After retraction of the plunger a radial movement of the finished cable/connector combination is all that is needed to remove the finished cable from the compression zone. The arrangement of the anvil apertures is such that separate releasing activation of the spring clips is not necessary. In an alternate embodiment, the anvil may have a tear-drop shaped aperture, either with or without a throat. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a side elevation view of the application tool of the present invention with the handle shown in an actuated position. 
           [0006]      FIG. 2  is an exploded perspective view of the application tool. 
           [0007]      FIG. 3  is a perspective view of a longitudinal section through the tool, with the plunger shown in a retracted position. 
           [0008]      FIG. 4  is a perspective view of a longitudinal section through the tool, with the plunger shown in an actuated position. 
           [0009]      FIG. 5  is a perspective view of a spring clip. 
           [0010]      FIG. 6  is a front elevation view of the spring clip of  FIG. 5 . 
           [0011]      FIG. 7  is a side elevation view of the spring clip, looking in the direction of line  7 - 7  of  FIG. 6 . 
           [0012]      FIG. 8  is a bottom plan view of the spring clip. 
           [0013]      FIG. 9  is a front elevation view of an anvil looking along line  9 - 9  of  FIG. 14 , with the outline of the tool base shown in phantom. 
           [0014]      FIG. 10  is a perspective view of a longitudinal section through the compression zone, showing an F-type connector loaded in engagement with the first anvil. 
           [0015]      FIG. 11  is a perspective view of a longitudinal section through the compression zone, showing an BNC-type connector loaded in engagement with the second anvil. 
           [0016]      FIG. 12  is a perspective view of a longitudinal section through the compression zone, showing an RG-11 F-connector loaded in engagement with the fixed anvil. 
           [0017]      FIGS. 13 and 14  are perspective views of the application tool with portions broken away to illustrate adjustment of the lock nut and plunger. 
           [0018]      FIGS. 15 and 16  are perspective views of the application tool, with portions broken away in  FIG. 16 , illustrating the connector seating holder and its use. 
           [0019]      FIG. 17  is a perspective view of the application tool looking toward the forward end of the compression zone. 
           [0020]      FIG. 18  is a view similar to  FIG. 9 , showing an alternate embodiment of the anvil. 
           [0021]      FIG. 19  is a view similar to  FIG. 9 , showing a further alternate embodiment of the anvil. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]      FIG. 1  illustrates the application tool of the present invention generally at  10 . The tool includes a base  12 . The details of the base are best seen in  FIGS. 2 and 3 . The base includes a central block member  14  having a bore  16  formed therein. A generally three-sided heel section  18  extends rearwardly from the block member. The heel section is hollow and open at its lower side. Rounded ears  20  are formed at the rear of the heel  18 . There are transverse, aligned holes  22  in the heel above the ears  20 . Extending forwardly of the block member  14  is a beam  24 . About midway along the beam there is an enlargement  26  which includes a transverse hole  28 . Forwardly of the enlargement  26  the front portion of the beam  24  carries a depending anvil mount  30 . Above the anvil mount there are two side walls  32 ,  34  joined to the beam  24 . The side walls extend back to the block member  14 . There are windows  36  in the side walls. Two transverse slots  38 ,  40  are formed in the anvil mount  30 . These slots extend up into the side walls  32 ,  34  as best seen in  FIG. 2 . Together the front surface of the block member  14 , the top surface of the beam  24  and the inside surfaces of the side walls  32 ,  34  define a compression zone  42  having a longitudinal axis A. At its forward end the side wall  32  joins an abutment  44  which has a rearwardly-facing, fixed bearing surface  46 . Fixed bearing surface  46  extends transversely of the axis A. Similarly, side wall  34  terminates at an abutment  48  which includes a fixed bearing surface  50 . See  FIGS. 15 and 17  also. The bearing surfaces  46 ,  50  are coplanar. It will be noted that the forward ends of the abutments  44 ,  48  have a curved lower portion which, taken together, define Unshaped opening  52  into the compression zone. 
         [0023]    The front or nose of the anvil mount  30  has a connector seating holder  54 . In this embodiment the holder  54  is a hexagonal depression in the anvil mount with a central post  56  disposed in the depression. The post  56  surrounds a bore  58  ( FIG. 3 ) that extends longitudinally into the anvil mount  30 . The depression is sized to receive the front end of a compression connector therein. The holder  54  retains the connector while a prepared cable is seated on the back end of the connector prior to compression. Further details of this process will be described below. 
         [0024]    Attention will now be turned to the components attached to the base  12 . First and second anvils  60  and  62  are retractably insertable into the compression zone  42  between open and closed positions. A complete anvil comprises two spring clips and a clip spring. Thus, first anvil  60  has a left spring clip  60 A, a right spring clip  60 B and a clip spring  60 C. Similarly, anvil  62  has a left spring clip  62 A, a right spring clip  62 B and a clip spring  62 C. The spring clips of the first anvil  60  are mounted in the transverse slot  38  of the anvil mount  30 , as seen in  FIGS. 3 and 4 . The spring clips of the second anvil  62  are similarly mounted in the transverse slot  40 . All of the spring clips are pivotally mounted on a spring pin  64  which is set in the bore  58  of the anvil mount  30 . 
         [0025]    Details of a spring clip  62 B are shown in  FIGS. 5-8 . In this embodiment all of the four spring clips used in the two anvils are identical so all the others would look the same as  62 B shown, except the installed left spring clips would be flipped around from the orientation shown in  FIG. 5 . The spring clip has a plate  66 . The rear surface of the plate defines a bearing surface. The plate is bounded on top by a head  67  and on one side by a generally vertical edge  68 . Near the bottom of the vertical edge is a knuckle  70  extending therefrom. At the lower portion of the plate a foot  72  carries a peg  74 . On the side edge of the plate opposite the knuckle  70  there is a circular ring  76 . An opening  78  extends through the ring. The opening receives the spring pin  64  when the clips are mounted in the anvil mount  30  so the slips are reciprocally movable into and out of the compression zone  42 . The ends of the clip springs  60 C or  62 C seat on the pegs  74  and normally bias the upper portions of the spring clip toward one another, i.e., into the compression zone  42 . It will noted that the ring has half the thickness of the remainder of the plate, as seen in  FIGS. 5 ,  7  and  8 . Thus when two spring clips are placed with their rings adjacent one another and the axes of the openings  78  aligned, the faces of the spring clips will be coplanar. This allows the spring clips to fit fairly snugly in the transverse slots, with sufficient clearance for easy movement but without allowing the spring clips to cant in their slots. 
         [0026]    Above the ring  76  the edge of the plate has an aperture  80 . The aperture is beveled at the front and rear faces of the plate. In this case the aperture is circular, although its shape could be other than a circle. The center of the aperture circle is at C. The horizontal centerline of the aperture is shown at B. It defines upper and lower quadrants U and L of the aperture  80 . The portion of the plate edge that defines the aperture in the lower quadrant L, i.e., the edge portion below the centerline B can be considered a support surface  80 A. The portion of the plate edge that defines the aperture in the upper quadrant U, i.e., the edge portion above the centerline B defines a retention surface  80 B. The retention surface in this embodiment defines a circular arc. The retention surface terminates in the upper quadrant at terminus T. An angle between the horizontal centerline and a radius R through the terminus T defines what will be referred to herein as a closure angle α. By way of example, and not by limitation, the closure angle in the illustrated embodiment is about 50°. The terminus is joined to the head  67  by an entry surface  82  which is angled from the vertical to assist in guiding a cable into the aperture. 
         [0027]    The closure angle α is important because it determines the ability of the spring clips to capture and release a cable inserted into the tool&#39;s compression zone. This will become evident by examination of anvil  62  in  FIG. 9 . As mentioned above, the complete anvil  62  comprises the left and right spring clips  62 A and  62 B and clip spring  62 C. The apertures  80  of the cooperating spring clips lie side by side to define a cable receiving receptacle. There is a throat or gap G between the terminus points of the two spring clips&#39; apertures. It is important to properly size this throat or gap such that coaxial cables can be readily inserted into and removed from the receptacle but at the same time the clips will impart a retaining force that prevents inadvertent slippage of the cable from the receptacle. In other words, a cable receptacle having a completely open slot at its entry point is undesirable because the cable is then totally free to move out of position for crimping. The spring clips must surround a portion of the upper quadrants of a cable therein to provide a retaining function. But the spring clips can only surround a portion of the cable. If the spring clips fully surround the cable they prevent ready release of the cable when it is finished, which would then require the awkward manipulation of the clips as described above. Thus, the spring clips must provide some, but not too much, restraint on a cable in the cable receiving receptacle. The compromise struck by the present invention between too little and too much restraint can be defined in two ways. One is by describing the closure angle as being at least 33° and not more than 75°. About 50° is preferred. This will extend the clip surface defining the aperture  80  sufficiently into the upper quadrant L to engage enough of an inserted cable to hold it for crimping and release it after crimping. Alternately, since the retention surfaces of the apertures  80  need not be circular, the throat or gap C between the terminus points of the apertures could be about 0.075 inches to about 0.250 inches, with about 0.19 inches being preferred. It has been found that a throat or gap of this amount will provide sufficient holding force on a cable in the receptacle prior to crimping while readily releasing a cable after crimping. 
         [0028]    Returning now to  FIGS. 1-3 , the remaining parts of the application tool will be described. A cylindrical slide rod  84  is mounted for slidable translation in the bore  16  of the block member  14 . The rod has a threaded bore  86  at its forward end and a clevis  88  at its rear end. A push head  90  has a slot  92  at its forward end. Much of the body of the push head has external threads which engage the internal threads of the slide rod  84 . Together the slide rod  84  and push head  90  form a plunger. A lock nut  94  has internal threads and external teeth. The lock nut is threaded on the push head and is engageable with the leading edge of the slide rod to prevent rotation of the push head.  FIGS. 13 and 14  illustrate how the overall length of the plunger is adjustably fixed. To change the length of the plunger, a user inserts a screwdriver blade into the compression zone  42  to engage the teeth of the lock nut and loosen it from the slide rod. This then permits a screwdriver engaged with slot  92  in the push head to rotate the push head as needed to lengthen or shorten the plunger. Once the desired length is obtained by turning the push head, the lock nut  94  is tightened against the end face of the slide rod to prevent further rotation of the push head. Thus, the length of the plunger can be easily adjusted using ordinary tools that are always available. 
         [0029]    A push rod  96  connects to the clevis  88  of the slide rod  84  by means of a groove pin  98 . The groove pin fits transversely through aligned openings in the clevis and slide rod. A second groove pin  99  joins the other end of the push rod  96  to a handle  100 . The handle has an elongated arm  102  connected at one end to a clevis  104 . Aligned openings in the clevis  104  receive the groove pin  99 . Another set of openings in the clevis receive a handle anchor pin  106 . Anchor pin  106  extends through the holes  22  in the ears  20  to mount the handle for rotation about the pin. An anchor pin screw  107  threads into the end of the pin  106  to fix it in position. 
         [0030]    The anchor pin  106  also fits through a torsion spring  108 . One leg of the spring engages the inside of the heel  18  and the other leg engages the arm  102  to bias the arm away from the heel. A U-shaped wire hasp  110  has free ends which slip into either end of the transverse hole  28  in the beam  24 . The hasp pivots between open and closed positions where it either releases the handle or holds it in the closed position of  FIG. 1 . A handle grip  112  slides over the arm  102  to provide a comfortable surface for a user to grasp. The hasp  110  is large enough to accommodate the grip  112 . 
         [0031]    The use, operation and function of the application are as follows. The user first sets the plunger to the desired length as described above. The hasp  110  is rotated toward the anvil mount  30  to release the handle  100 . The torsion spring biases the handle open position as seen in  FIG. 3 . This rotates the handle clevis  104  away from the block member  14  and causes retraction of the push rod  96  and slide rod  84 . The tool is now ready for use. The user prepares coaxial cable by stripping it appropriately and seating the desired connector type on the stripped cable end. The connector seating holder  54  can be used to assist in inserting the cable the requisite distance into the connector. As seen in  FIGS. 15 and 16  a user grasps the tool  10  in one hand and puts a connector  114  loosely on the end of a coaxial cable  116 . The free end of the connector is then inserted into the depression of the seating holder  54 . The user can then press the tool and cable together to push the connector the required distance onto the cable. As this is done there is no possibility of the user being injured by a sudden thrusting of the central conductor of the cable through the front end of the connector. 
         [0032]    Once the connector is properly seated on the cable, the connector/cable combination is placed into the compression zone  42  by a radial movement between the side walls  32 ,  34 . The cable engages the entry surfaces of the spring clips and forces them apart sufficiently to permit the cable to fit into the cable receiving receptacle defined by the apertures  80  of the spring clips. Once the cable enters the receptacle the clip springs  60 C and  62 C will push the spring clips back to a closed position about the cable wherein the upper quadrant of the spring clip will engage the cable. The cable will extend out the front of the tool through the U-shaped opening  52 . The rear edge of the connector engages the bearing surfaces of one of the movable anvils or the abutments, depending on the size of the connector.  FIG. 10  illustrates that a typical F-type connector  1118  will engage the first anvil  60 .  FIG. 11  shows a BNC connector  120  in engagement with the second anvil  62 .  FIG. 12  illustrates that an RG-11 F-connector  122  is so large that its rear edge will extend all the way to the fixed bearing surfaces  46 ,  50  of the abutments  44 ,  48 . 
         [0033]    With the rear edge of the connector in engagement with the appropriate bearing surface the user squeezes the handle  100  toward the base  12 . The push rod  96  then pushes the plunger forwardly. The push head  90  engages the front end of the connector. Continued movement of the slide rod and push head combination compresses the connector between the push head and the bearing surfaces, thereby compressing the connector and locking it onto the cable. The user then releases the handle  100 . The torsion spring  108  moves the handle to the open position, which causes the plunger to retract and disengage the connector. With the other hand, the user can then translate the finished cable out of the compression zone by a radial movement out the top of the compression zone. There is no need to manually engage the spring clips because their shape allows the user to simply lift the cable out of the compression zone. The spring clips will release the cable without undue effort on the part of the user. The tool is then ready for the next application. When the user is finished, the handle can be closed and the hasp rotated to retain the handle in the closed position. 
         [0034]      FIG. 18  illustrates an alternate embodiment of an anvil  124 . This anvil has left and right spring clips  124 A,  124 B. These may be generally similar to the spring clips described above except for the shape of the aperture  126 . Aperture  126  has a tear-drop shape. That is, the lower quadrants of the aperture are circular but the retention surfaces in the upper quadrants have both a circular portion  126 A and a tangential portion  126 B. The circular portion  126 A defines an arc above the horizontal centerline B of about 30°. The retention surface then merges into the tangential portion  126 B, which is generally straight. The tangential portion ends at terminus T. There is a gap or throat G between the termini of the two spring clips. 
         [0035]      FIG. 19  illustrates a further alternate embodiment of an anvil  128 . As is the case with all the anvils, anvil  128  has left and right spring clips  128 A,  128 B which are similar to those described above except for the shape of the aperture  130 . Aperture  130  has a tear-drop shape similar to the aperture  126  but in this case there is no gap or throat between the clips. Thus, the lower quadrants of the aperture are circular but the retention surfaces in the upper quadrants have both a circular portion  130 A and a tangential portion  130 B. The circular portion  130 A defines a circular arc above the horizontal centerline of about 30°. The aperture then merges into the tangential portion  130 B. As shown in the figure, the tangential portion  130 B defines an angle of greater than 35° with the horizontal centerline B. The tangential portion may have a small arc at its upper end just prior to terminus T. The termini are in contact with each other when the spring clips are closed. There is no gap or throat between the termini of the two spring clips. 
         [0036]    In both of the tear-drop configurations of  FIGS. 18 and 19 , the retention surface defined by the arcuate portion and the tangential portion provides the desired balance between retention ability before and during compression and ease of release after compression. It will be understood that the retention surface could have shapes other than the tear-drop configuration shown. For example, instead of having an arcuate portion, the retention surface could just have a straight tangential portion starting at the horizontal centerline. In such a configuration the tangential portion would not be tangential to the support surface in a strict geometric sense, but it will be understood that the term “tangential” as used herein is broad enough to cover alternative arrangements of the retention surface that do not meet strict geometric conditions. What is important is that the retention surface in these alternate embodiments have a portion that leads or slopes into the parting line between the spring clips. As a result of the leading configuration of the retention surface, outward radial movement of the cable will produce a lateral force on the spring clips that tends to separate the spring clips and allow release of the cable. The precise combination of arcuate, straight, curved or angular surfaces that comprise the retention surface may vary so long as the combination produces a lateral, separating force on the spring clips when a cable is moved radially outwardly of the compression zone. 
         [0037]    While the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, substitutions and alterations thereto without departing from the scope of the following claims.