Abstract:
An adaptable device for tensioning safety cable to a predetermined tension limit, crimping a ferule onto the cable, cutting the excess cable and ejecting the device from the crimped ferrule-cable assembly. The device compromises a tool body, a cable tensioner and an elongated nose. The cable tensioner comprises a handle for applying tension to a cable inserted into the tension gripper mechanism and a one-way clutch to prohibit movement in a direction which would unwind the cable or lessen the tension applied. The elongated nose has a ferrule receiving aperture for receiving a ferrule and passing the safety cable there through. A plunger is reciprocally operative in the nose piece to crimp the ferrule onto the cable, cut the excess cable and eject the device from the crimped ferrule-cable assembly. The Plunger is actuated either manually or by means of an attached power assisted tool. The elongated nose piece is removable so it can be interfaced with different tool bodies.

Description:
FIELD OF INVENTION 
     The present invention relates to a device for attaching steel cable sometimes referred to as safety cable (or lock wire or wires) to releasable fasteners and, more particularly, to an adaptable device for tensioning, locking and terminating safety cable while simultaneously ejecting the device from the attached steel cable-fastener assembly. 
     BACKGROUND OF THE INVENTION 
     Various types of machinery are subject to vibration that can loosen nuts and bolts. Lock wire has long been used as protection to resist such loosening. Lock wire secures two or more elements together so that the loosening of one element is counteracted by the tensioned wire running through the elements. Most often in a lock wire configuration, two wire strands are wrapped together and then separated such that one strand goes through the bolt or nut head and the other strand goes around the bolt or nut head; the rejoined ends are twisted together, again, on the exiting side of the nut or bolt and so on. Once the wire strands have been inserted through and around all of the nuts or bolts in a particular grouping, the remaining free ends of the wire strands are secured by twisting the terminated ends of the wire strands together. 
     In large part in the area of machinery vibration, the lock wire method of grouping bolts together has been replaced with steel cable (also referred to as safety cable). Steel cable is made from an assembly of steel wire laid (or twisted) into a helix to produce a strong resilient material. Notwithstanding the strength of steel cable, the termination of a steel cable often results in ends which easily fray. Further, the resultant resiliency of the steel cable makes it difficult to secure the terminated ends by twisting the steel cable ends together. As such, the terminated ends of steel cable passed through holes in a series of nuts or bolts subject to operational vibration is usually secured by a ferrule crimped onto the free end of the cable to secure the cable to the assembly. 
     In this arrangement, it is often necessary to obtain a predetermined tension on the steel cable looped through the holes in a grouping of nuts and bolts before securing the free end of the steel cable with a ferrule and terminating the excess safety cable. Prior art devices use a pocket into which the ferrule sits where the crimping occurs. This arrangement often requires twisting or other manipulation by the operator to remove the device from the crimped cable-bolt assembly. This movement often compromises the pre-set tension limit on the crimped cable-bolt assembly. It is an object of the present invention to provide a device that allows tensioning of the steel cable to a predetermined limit, ferrule crimping, steel cable free end termination and ejection of the device from the crimped steel cable secured grouping of nuts or bolts without compromising the pre-set tension of the safety cable. 
     SUMMARY OF THE INVENTION 
     A device used for tensioning steel cable to a mechanically set limit (typically on a grouping of bolts on a machine subject to vibration) and crimping a ferrule onto the cable while simultaneously terminating the excess cable and ejecting the device from the crimped ferrule-steel cable assembly when the steel cable has been tensioned to the mechanically set tension limit. The device includes a manual actuator for gripping and pulling the steel cable to the desired tension limit. A mechanical configuration implemented for crimping the ferrule onto the steel cable when the tension limit has been reached. The mechanical configuration being operative to sever the free end of the steel cable and eject the device from the crimped ferrule-steel cable assembly concurrent with crimping the ferrule onto the terminated end of the steel cable. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a top plan view of the prior art bolt head lock wire configuration; 
         FIG. 2  is a top plan view of a safety cable system applied using the device according to the present invention; 
         FIG. 3  is a top planar view of a device according to the present invention; 
         FIG. 4  is an enlarged partial cut away view along axis A-A of the tip portion of the device depicted in  FIG. 3 ; 
         FIG. 4 a    is a partial enlarged top plan view of the tip portion of the device depicted in  FIG. 5 ; 
         FIG. 4 b    is a cross-sectional view of the partial cut away view depicted in  FIG. 4  taken along line B-B; 
         FIG. 5  is a side plan view of the nose portion of the device according to the present invention; 
         FIG. 6  is a side plan view of the tool body portion of the device according to the present invention; 
         FIG. 7  is an isometric view of the tensioning assembly associated with the present invention; 
         FIG. 8  is a planer view of the tension gripper shaft of the tensioning system associated with the present invention; 
         FIG. 9  is a side view of the tension gripper shaft of the tensioning system associated with the present invention; 
         FIG. 10  is an isometric view of the tensioning mechanism housing associated with the present invention; 
         FIG. 11  is a side view of the tensioning mechanism housing associated with the present invention; 
         FIG. 12  is an enlarged planner view of the ratchet mechanism associated with device according to the present invention; 
         FIG. 13A-13C  are views of the operation of the ratchet mechanism of the device according to the present invention; 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The Present invention will now be described in terms of the presently preferred embodiment thereof as illustrated in the drawings. Those of ordinary skill in the art will recognize that many obvious modifications may be made thereto without departing from the spirit or scope of the present invention. 
     A lock wire  18  applied in accordance with the prior art is illustrated in  FIG. 1  wherein threaded fasteners  10 ,  12  and  14  are engaged with a portion  16  of a rotating apparatus (not otherwise shown). The lock wire  18  comprises two wire strands  18   a  and  18   b  twisted together at one end are separated such that strand  18   a  passes through a transverse opening in fastener  10  while strand  18   b  passes around the exterior of the fastener  10 . The strands are twisted together on the opposite side of fastener  10  and, again, one strand passes through a transverse opening formed in fastener  12  while the other strand passes around fastener  12 . The lock wire  18  continues until the last fastener, in this particular instance fastener  14 , whereupon one strand passes through a transverse opening in the fastener, while the other strand passes around the exterior of the fastener. The strands are twisted together on the opposite side of the fastener  14 . 
       FIG. 2  illustrates a safety cable system applied using the apparatus according to the present invention. Threaded fasteners  10 ,  12  and  14  are once again engaged with the machinery portion  16 . Safety cable  20  comprises a multi strand cable having a motion stop ferrule  22  affixed to end  20   a . Safety cable  20  passes through transverse openings formed in the threaded fasteners  10 ,  12  and  14  until ferrule  22  bears against one side of fastener  10 . At this point, ferrule  24  is inserted over the end of cable  20  against the side of fastener  14 , a tension is applied to the safety cable  20  and the ferrule  24  is crimped onto the safety cable such that it bears against a side of the fastener  14  thereby securing the cable to the series of fasteners through which it is threaded. Safety cable  20  is then automatically trimmed. The pre-determined tension is maintained in safety cable  20  by the contact of ferrules  22  and  24  with the sides of the threaded fasteners  10  and  14 , respectively. 
     As best illustrated in  FIG. 5  &amp;  FIG. 6 , the device according to the present invention comprises a pair of handle members  26  and  28  pivotally attached together via pivot pins  32  and  34  so as to pivot about the longitudinal axis of the pivot pins  32  and  34  toward and away from each other as illustrated by arrows  31 . The handle members  26  and  28  may have cushioned or coated hand gripping areas  26   a  and  28   a , respectively. 
     The elongated nose portion  46  ( FIG. 5 ) is pivotally attached via pivot pins to handles  26  and  28  at location  32  and  34 . Plunger  50  is captured in the inner cavity of  46  by a spring loaded set screw mechanism  FIG. 5 . The proximal end of Plunger  50  sits on the flat of pin  30  pivotally attached to handle members  26  and  28 . Pin  30  engages  50   b . See  FIGS. 5 and 6 . 
     Elongated nose portion  46  also has a distal end portion  46   b  which includes a ferrule receiving opening  48 , the outer most portion of which is open as illustrated in  FIG. 5 , the opening including a proximal end  46  adjacent punch driving member  50  and an opposed distal opening  46   b .  FIG. 5 . Elongated nose portion  46  has a longitudinally extending, central opening which slidably accommodates crimping punch driving member  50 .  FIG. 5 . Driving member  50  has an end  50   a  which sits on the flat portion of pin  30  which provides for it to be extended by manipulation of handle members  26  and  28  by pivot pins  32  and  34 . As will be hereinafter explained in more detail, the driving member  50  is movable between a retracted position at which a crimping punch distal end  50   a  does not extend significantly into opening  48  and a crimping position at which punch  50   a  extends into the opening  48  effectively pushing through into the opening and forcing the ferrule through the opening  46   c  so as to crimp the ferrule onto a safety cable extending through the ferrule.  FIG. 4A . As will be described below, a cable receiving aperture  70  extends into the bottom of opening  48 .  FIG. 4  and  FIG. 4B . 
     In order to use the device according to the present invention, the safety cable must first be threaded through a ferrule as well as the aperture  70 ; a tension must be applied to the safety cable to a predetermined value; and the ferrule must be permanently crimped onto the safety cable. 
     The first portion of the operational procedure may be carried out with the assistance of a ferrule holding cartridge as is generally known to those of ordinary skill in the art. Generally, the ferrule holding member may have a magazine portion defining a storage chamber adapted to accommodate a plurality of ferrules  24 . 
     Once the desired amount of safety cable  20  has been pulled through the threaded member  14 , the ferrule  24  and the nose portion  46 , the ferrule holding member, if employed, is removed. At this point, it is necessary to apply a predetermined tension to the safety cable  20  before permanently attaching ferrule  24  to the cable by crimping. This is accomplished by attaching the end of safety cable  20  to a tensioning device, generally indicated in  FIG. 7 . The tensioning mechanism is illustrated in  FIGS. 7-11 . The tensioning mechanism according to the present invention comprises a one-way rotation mechanism, which may be any known, commercially available device.  FIG. 8 . The tension gripper shaft  84  has four slots so that the cable may be locked by being inserted into two of the slots in a 90 degree configuration.  FIG. 8 . The winding member  86  is attached to the tension gripper shaft by way of a one-way bearing press fit into a housing  85 .  FIG. 8 . The winding member  86  will operate only in one direction so that it can only apply tension to the cable and cannot operate to loosen the cable once the cable is engaged onto the tension gripper shaft.  FIG. 7  and  FIG. 8 . The winding member is rotated to apply tension to the cable.  FIG. 7 . When the desired tension is reached, the one way bearings in the tensioning mechanism prohibits the cable from unwinding from its tensioned position while the ferrule is crimped onto the cable. The winding mechanism is contained in a housing  85  with two set screws  87  which allow the entire tensioning mechanism to slide along the elongated nose piece.  FIG. 10  and  FIG. 11 . 
     Once the proper tension has been applied to the safety cable  20 , the ferrule  24  may be crimped onto the safety cable. This is achieved by manually urging handle members  26  and  28  towards each other. As illustrated in  FIG. 6 , such movement of the handle members  26  and  28  will cause pivot pins  32  and  34  to move around their respective axis points and thereby urging pin  30  against which crimping punch driver  50  sits at  50   b .  FIG. 5  and  FIG. 6 . Such movement causes relative movement between the nose portion  46  and the crimping punch driver  50 .  FIG. 5 . 
     As best seen in  FIGS. 4A and 6 , moving the handles  26  and  28  towards each other will cause driver  50  to move toward the left with respect to nose portion  46  from the retracted position to the crimping position. As specifically shown if  FIG. 4A , the extending motion of the crimp punch  50   a , forces the ferrule-cable assembly through restriction  46   d  which deforms the ferrule  24  so as to be crimped and permanently attached to safety cable  20 . The restriction  46   d  is defined by two flats  46   c . The flats  46   c  initially engage the ferrule  24  as it is pushed through the restriction  46   d  in order to start the crimping process and reduce the stress experienced in the area of  46   d . This process allows the ferrule  24  to be crimped to the cable  20  before the cable  20  is engaged by a cutting plate  250  shown in  FIG. 4  and as described below. The nose piece  46  is plated with a material with a high Rockwell Hardness to facilitate the crimping function and to provide wear resistance, such as HRC 55-66. Specifically, as the ferrule  24  is pushed toward the distal end of  46 , it is initially engaged by the two flats  46   c  at the entrance to the restriction  46   d  which deforms the outer ring of the ferrule  24 , so that the ferrule  24  and the cable  20  running through it can be pushed through restriction  46   d  and thereby crimped and joined together.  FIG. 4  and  FIG. 4A . 
     The detail of the ferrule crimping portion of the tool is illustrated in  FIGS. 4, 4A and 4B . The tip of the ferrule crimping punch  50   a  (that will come into contact with the ferrule when extended) is slightly angled to an edge at the portion of the tip of the crimping punch  51   a  in contact with the cutting plate  250  as shown in  FIG. 4 . The tip of the plunger  51   a  is fabricated from hard wear resistant material such as carbide; alternatively, this area can be coated with a hard wear resistant coating to improve the wear characteristics of the crimping and cutting portion of the device. 
     The crimping punch  50   a  slides over hole  70  in nose portion  46  when the punch is extended in the direction of the crimping position towards the distal opening in  46  to assist in the shearing action used to cut the free end of cable  20  away from the ferrule during crimping. As shown in cross section  FIG. 4B , hole  70  in nose portion  46  forms a pocket angled toward the direction that the safety cable  20  will enter the device to facilitate the advancement of the safety cable through hole  70  during the drive stroke of the crimp punch  50 . Crimping forces the ferrule  24  to be pushed through opening  46   d  in nose portion  46  as it is being forced out of the tool by the crimp punch  50  as shown in  FIG. 4A . The relative movement as described above causes shearing of the cable  20  protruding through hole  70  on  46   b  by the plate  250 .  FIG. 4A . Specifically, a replaceable cutting plate  250  preferably made of hardened metal such as tool steel is provided at the bottom of opening  48  to improve the wear characteristics of the crimping and cutting portion of the tool.  FIG. 4A . The plate  250  provides a sharpened edge against which the cable  20  is urged by ferrule  24  during crimping to thereby cause shearing of the cable adjacent the lower surface of the ferrule  24 .  FIG. 4B . The plate  250  may be constructed so as to be replaceable to increase service life of the tool. 
     In accordance with the embodiment of  FIG. 4 , the crimping punch  50   a  includes a flattened bottom section 5 lb that slides over plate  250  when the punch is extended towards the crimping position to assist in the shearing action used to cut the free end of cable  20  away from the ferrule during crimping. The crimping punch  50   a , of course, is also located so as to be closely adjacent to the bottom of opening  48  next to the cutting plate  250  when the ferrule  24  is being deformed by restriction  46   d  by the urging of the crimping plunger.  FIG. 4 . 
     To ensure that the ferrule  24  is disposed contiguous with hole  70  in the nose portion  46  during crimping, the depth of opening  48  is selected such that the height of a ferrule  24  to be crimped by the tool is always slightly greater than the depth of the opening  48  to ensure that the ferrule, which is disposed between fastener  14  and plate  250 , is pressed through restriction  46   d  when the tool is operated as shown in  FIG. 4 . The outer flange of the ferrule  24  is disposed in the opening shown in  FIG. 4A  and gently rests against the sides of the opening  48  in the elongated nose portion  46  before crimping.  FIG. 4A . 
     An alternative embodiment of nose portion  46  allows for the nose piece to be removed and accepted by many different tool bodies.  FIG. 5 . For example, tool bodies operated manually, tool bodies operated electrically or by battery power, tool bodies operated by hydraulic means and tool bodies powered by pneumatic means. 
     During the drive stroke of crimp punch  50 , in order to prevent the movement of handle members  26  and  28  away from each other before the ferrule  24  has been permanently attached to the safety cable  20 , ratchet mechanism  112  is provided. As best seen in  FIGS. 6, 12 and 13A-14C , ratchet mechanism  112  comprises a ratchet body  114  attached to handle member  26  via pivot pin  116 . It also comprises a support body  118  attached to handle member  28  via pivot pin  120 . Ratchet member  124  is attached to the support body  118  via threads  126 . Ratchet member  124  also extends through the ratchet body  114  and defines a plurality of ratchet teeth  128  extending over a length of the ratchet member  124 . Ratchet member  124  also defines ratchet grooves  130  located at either end of the ratchet teeth  128 . The depth of ratchet teeth  130  is greater than that of ratchet teeth  128  as illustrated in  FIG. 12 . 
     Pawl  132  is pivotally attached to ratchet body  114  via pivot pin  134 . Resilient biasing members  136   a  and  136   b  are located on opposite sides of pawl  132  and exert a biasing force thereon urging it to the central position illustrated in  FIG. 12 . Compression spring  138  is operatively interposed between the ratchet body  114  and support body  118  so as to normally urge these elements apart. 
     The operation of the ratchet mechanism can be seen from  FIGS. 13A-13C . Movement of handle members  26  and  28  towards each other will cause ratchet body  114  and support body  118  to also move towards each other. Thus, ratchet body  114  moves in the direction of arrow  138  in  FIG. 13A  relative to ratchet member  124 . Pawl  132  defines an engagement edge  140  which, when the ratchet body  114  is displaced towards support body  118 , engages ratchet teeth  128 . The movement of ratchet body  114  will cause pawl  132  to pivot about pivot pin  134  so as to compress resilient biasing member  136   a . This compression will increase the force urging the pawl  132  toward its central position illustrated in  FIG. 13 . However, the depth of the ratchet teeth  128  is insufficient to allow the pawl  132  to return to this position. 
     Thus, once the engagement edge  140  engages ratchet teeth  128 , it is impossible for ratchet body  114  to move in any direction other than that indicated by arrow  138  in  FIG. 14A . This prevents the handles  26  and  28  from being moved apart as long as pawl  132  is engaged with ratchet teeth  138  to prevent partial crimping of a ferrule. Once the handles  26  and  28  have been moved towards each other sufficiently for the crimping punch  50  to have fully crimped the ferrule  24  onto the safety wire  20 , the ratchet body  14  and the support body  118  will be in the positions illustrated in  FIG. 13B . In this position, engagement edge  140  of pawl  132  enters the lower ratchet groove  130  which has a depth sufficient to allow the pawl  132  to be returned to its central position due to the biasing force of resilient biasing member  136   a .  FIG. 13B . 
     Once the engagement edge  140  enters the groove or ratchet tooth  130 , ratchet  114  and support body  118  may move away from each other, as illustrated in  FIG. 13C . Movement of ratchet body  114  relative to support body  118  in the direction of arrow  142  will bring engagement edge  140  once again into contact with ratchet teeth  128 . The depth of the ratchet teeth  128  will cause the pawl  132  to pivot about pivot pin  134  and compress resilient biasing member  136   b . This depth, however, is insufficient to allow the pawl  132  to return to its center position. This prevents movement of ratchet body  114  in any direction except that indicated by arrow  142 . Once ratchet body  114  reaches the position illustrated in  FIG. 12 , the upper ratchet groove  130  will enable the pawl  132  to be returned to its center position by resilient biasing members  136   a  and  136   b.    
     Those of ordinary skill in the art will recognize that the embodiments just described merely illustrate the principles of the present invention. Many obvious modifications may be made thereto without departing from the spirit or scope of the invention as set forth in the appended claims.