Patent Publication Number: US-8528603-B2

Title: Tie guide channel for cable tie installation tool

Description:
BACKGROUND 
     The present invention relates generally to a tool for the automatic installation of a cable tie around a bundle of wires and, more specifically, to a guide channel for such a tool that improves cable tie feed to avoid cable tie jams resulting from bounce back. 
     A wide variety of cable tie application tools are known. Some provide individual cable ties from a remote dispenser having a cartridge or reel containing a large number of cable ties to a conveyance mechanism for provision to the application tool. 
     One special type of cable tie application tool has used the application of pressurized air to convey the individual cable ties from the dispenser to a hand manipulated application tool at very high rates of speed, propelling cable ties to a cable tie tool head at up to 50-80 MPH, for application to a bundle of wires. Examples include U.S. Pat. No. 3,946,769 to Caveney et al., U.S. Pat. No. 4,004,618 to Turek, U.S. Pat. No. 4,498,506 to Moody et al., and U.S. Pat. No. 5,722,466 to Levin et al. Tools based on these patents are also commercially available from Panduit Corporation and marketed under the tradenames PAT1M for use with cable bundles up to about 0.82″, PAT1.5M for bundles up to about 1.31″, and PAT2S for bundles up to 2″ in diameter. 
     These remote dispenser cable tie installation tools are very desirable and have been highly successful for situations where maximum volume and speed of application is necessary. However, due to the very high operating rates of speed, cable tie jams within the guide channel of the tool or incomplete cable tie attachment occasionally occur, which may result in extensive delays and repair costs that can be very significant. In particular, as the feed rates increase, forces acting on the fed cable tie as it is rapidly stopped by a head stop assembly can cause a tendency for the cable tie to “bounce back” in a rearward direction from the head stop assembly back towards the guide channel. 
     Certain existing models of cable tie application tools include a guide channel mechanism that assists travel of the cable tie through the channel and may resist some “bounce back.” The mechanism includes use of two biased side members or a single biased, pivotal lower guide surface. Examples of these are shown in U.S. Pat. No. 4,498,506 to Moody et al., U.S. Pat. No. 4,004,618 to Turek, and U.S. Pat. No. 5,845,681 to Kurmis. Such tools were intended for low dispense speeds. However, with certain tools requiring higher dispense feed rates, secure retention of the cable tie head becomes problematic because the biased guide members may not respond quick enough to fully prevent “bounce back.” 
     SUMMARY 
     It is an object of the present invention to provide an improved cable tie installation tool having a fixed cable tie guide channel mechanism that assists in retention of cable tie heads in a cable bundling position and prevents bounce back of the cable tie head back into the guide channel. 
     It is another object of the present invention to provide an improved cable tie installation tool having a cable tie channel mechanism that provides a backup or redundant guide structure that resists cable tie bounce back. 
     It is a further object of the present invention to provide a cable tie guide channel mechanism for a cable tie installation tool that does not suffer problems with reaction speed so that reliability at high delivery speed rates can be achieved. 
     In certain embodiments, the cable tie guide channel mechanism is in the form of a replacement insert. In other embodiments, the cable tie guide channel mechanism is an integral part of the channel. 
     In various embodiments, the guide channel includes a biased pivotal guide surface facing one side of the guide channel and a fixed guide channel mechanism including a fixed ramp surface opposite the biased pivotal guide surface. The fixed ramp surface includes a retaining wall substantially perpendicular to the guide channel and facing a distal end thereof. The ramped surface guides one-way entry of the cable tie into the cable tool head through the guide channel, while the biased pivotal guide surface sizes the channel to receive the cable tie therethrough. Upon the cable tie passing the guide channel section, the biased pivotal guide surface is biased upward to restrict the guide channel size and engage a retaining wall of the pivotal guide surface with a rear of the cable tie head. The retaining wall surface on the fixed ramp also restricts rearward movement of the cable tie head by engaging a top rear surface of the head, regardless of whether the pivotal guide surface has fully retracted. 
     In certain embodiments, the cable tie guide channel mechanism operates as a back-up or complement system to a biased head retainer mechanism that acts to restrict the size of the cable channel upon passing of the cable tie head. In other embodiments, the fixed guide channel mechanism may be a standalone component when provided on a side opposite the jaw assembly. However, improved cable tie head retention and blockage may be achieved when both the fixed and movable retaining walls cooperatively engage both the top and bottom rear surfaces of the cable tie head simultaneously. 
     In accordance with certain aspects, the biased head retainer mechanism may form a bottom retention wall that blocks rearward movement of a bottom of a cable tie head while the cable tie guide channel mechanism forms a top retention wall that blocks rearward movement of a top of the cable tie head. The combination of these two mechanisms support both the top and bottom of the cable tie head to resist or restrain rearward movement of the cable tie head into tile channel. 
     In an exemplary embodiment, a cable tie installation tool automatically accepts a reel of cable ties mounted on a strip. The tool sequentially separates each cable tie from the reel and conveys the discrete cable tie to a remote installation tool at a high speed by pneumatic action where the cable tie is automatically installed around a bundle of wire or the like, tensioned at a predetermined value, and the tail severed and ejected. Each cable tie abuts a cable tie head stop to position the cable tie in a cable bundling position and is blocked from bounce back by a cable tie guide channel mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary automatic cable tie application tool to which the tie guide channel can be provided; 
         FIG. 2  is a partial cross-sectional view of the interior of a prior art cable tie installation tool showing a cable tie guide channel having a cable tie fed therethrough; 
         FIG. 3  is a partial cross-sectional view of the prior art tool of  FIG. 2  showing possible bounce back jamming; 
         FIG. 4  is a partial cross-sectional view of an exemplary tool according to a first embodiment; 
         FIG. 5  is a partial perspective view of the tool of  FIG. 4  showing the cable guide channel mechanism in the form of a removable or replaceable insert; 
         FIG. 6  is a partial cross-sectional view of a second embodiment of a tool; and 
         FIG. 7  is an enlarged portion of the cable tie tool of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A remote dispenser type cable tie application tool system using the application of pressurized air to convey individual cable ties to the hand manipulated tool is designated generally by the reference numeral  10  in the accompanying drawings. 
     As shown in  FIG. 1 , a cable tie application tool system  10  includes a cable tie application tool  12 , and a cable tie dispenser  14  connected to the tool  12  via a transfer tube  22 . The dispenser  14  is connected to a cable tie reel  16  and receives the individual cable ties  20  through a receiving drum  18 . The drum  18  of the dispenser  14  receives and positions the individual cable ties  20  for transfer into and through the transfer tube  22  into position within the application tool  12  for application by the tool jaws  26  around a bundle of wires  24 . Additional details on the general operation of the cable tie installation tool can be found in U.S. Pat. No. 4,498,506 to Moody et al. and U.S. Pat. No. 4,004,618 to Turek, and U.S. Pat. No. 5,722,466 to Levin et al., the disclosures of which are hereby incorporated herein by reference in their entireties. 
     During a normal cycle of advancing a cable tie through the tube  22  to tool  12 , when the user activates the trigger, a primary air burst is sent to move the loaded tie  20  through a cable tie passageway in tube  20  where it is advanced partway into the tube. The primary air blast is stopped to allow for the loading of the next cable tie  20  into position. A secondary air burst pushes the first cable tie  20  through the tube  22  and into a guide channel  30  of the tool  12  ( FIG. 2 ) where it is advanced toward a cable tie bundling position where the head of cable tie  20  is to be positioned opposite an opening  55  ( FIG. 3 ). At this position, the cable tie free end becomes encircled around a bundle and is suitably tensioned. Then, the free end is severed and ejected. 
     As better shown in  FIG. 2 , a conventional cable tie application tool  12  includes a guide channel  30  comprising a top wall  32  and a lower wall  34  that define the channel therebetween sized to allow guided passage of cable ties  20 . A biased head retainer assembly  40  is provided in certain models and is intended to bias upwards upon passing of the cable tie head  20  so as to narrow the entrance size of the guide channel  30  and engage the bottom of the cable tie head to prevent bounce back. A typical biased head retainer assembly  40  includes a main body pivotally attached to a pivot pin  42  and biased by a spring  44  to a position that extends the main body into the channel  30 . A damper  46  and a notched retainer wall  48  may also be provided. In use, as the cable tie  20  is passed through the channel  30  over the main body, the cable tie  20  overcomes the bias and allows the main body to pivot to enlarge the size of channel  30 . However, upon passing of the cable tie head  20  beyond the retainer assembly  40 , a properly working main body will spring upward into channel  30  so that the retainer wall  48  extends sufficiently into the channel to engage the bottom edge of the cable tie head ( FIG. 3 ). This restrains backwards movement of the cable tie to resist reentering back into the cable tie channel  30  due to forces acting on the head during contact with head stopper assembly  50 . 
     However, due to tile high speeds of delivery and limitations in the reaction speed of assembly  40 , particularly as it slows with age or usage, it is sometimes difficult for the head retainer assembly  40  to respond quick enough to catch the cable tie head  20 . For example, if the head retainer wall  48  does not respond quickly enough or becomes caught oil the bottom of the cable tie head  20 , the stiffness of the cable tie body can cause the cable tie  20  to retreat back into the tie guide channel  30  as illustrated in  FIG. 2 . This will improperly align the cable tie head and prevent proper mating of the cable tie free end through the cable tie head opening  55 . Moreover, this improper positioning will likely jam the machine and prevent proper ejection and feeding of subsequent cable ties without operator intervention. 
       FIGS. 4-5  illustrate a first embodiment of a cable tie application tool with an improved guide channel mechanism that improves blocking of “bounce back” and thus improves tool reliability to address problems with “bounce back.” The tool is similar to that shown in  FIGS. 1-3 , but adds an additional guide channel mechanism  60  on tile top of the guide channel  30  near the distal end of the channel. 
     In the illustrative embodiment, guide channel mechanism  60  is in the form of a removable insert that can be fitted to a distal end of the guide channel  30  by conventional means, such as a pin, dovetail, or press-fit connection.  FIG. 5  shows an exemplary embodiment in which the mechanism  60  is fitted by a pin (unshown) through the illustrated openings. Insert  60  includes a ramped surface  62  that ramps inward into the guide channel  30  to restrict the size of channel  30  towards the distal end. Insert  60  also includes a retention wall  64  near or at the far distal end of the insert oriented substantially perpendicular to channel  30 . The insert dimensions are sized depending on the particular tool and cable tie to allow entry of the cable tie therethrough in a forward direction with minimal interference. while retention wall  64  is of a sufficient height to solidly engage a rear surface of cable tie head  20  to restrain “bounce back” into the channel  30 . In the illustrated embodiment, a biased cable tie head retainer assembly  40  is provided opposite the insert to provide a retractable guide surface that can be urged downward by the force of the entering cable tie to effectively increase the channel size to allow passage of the cable tie therethrough in the forward direction. 
     During positioning of the cable tie into its cable tie bundling position, the resilient, but semi-stiff cable tie becomes wrapped around jaws  26 , which apply a compressive force upon the cable tie urging it from a straight to a wrapped state that encircles a bundle. Upon contact of the cable tie head with the cable tie head stop  50  ( FIG. 4 ), forces on the cable tie due to the abrupt stop against stop  50  and properties of the cable tie may cause “bounce back,” particularly when delivery speeds are high. During such “bounce back”, the cable tie due to its resiliency attempts to restore itself to its previous straight state as it travels rearward towards channel  30 . As a result, the cable tie head  20  will be urged rearward and outward towards the wall of channel  30  opposite tile jaws. In the illustrated example where the jaws are facing downward, this is the top surface of channel  30 . Accordingly, in this embodiment, the insert  60  is provided on the top side of channel  30 . However, if the jaws were located elsewhere, the insert location would accordingly change. 
     Because insert  60  is a fixed structure, retention wall  64  is immediately positioned to resist “bounce back” from cable tie  20  abruptly contacting stop  50 . Thus, even at high delivery speeds, effective control of “bounce back” can be achieved because there is no moving structure that needs time to be adequately positioned. Additionally, when the biased cable tie head retainer assembly  40  is provided opposite insert  60 , a more positive engagement “bounce back” resistive structure is achieved as the cable tie head can be supported on both top and bottom rear surfaces by contact with retention walls  64  and  48 . Moreover, even if the biased retainer assembly  40  is slow to respond after passage of cable tie head  20  thereby, the fixed cable tie guide channel mechanism  60  formed by the insert can serve as a back-up or redundant mechanism to prevent jams or misfeeds. 
     In an exemplary embodiment, retention wall  64  is spaced from stop  50  at a position that restrains rearward movement so that the slot in cable tie head  20  remains positioned in line with opening  55  in the tool ( FIGS. 4-5 ). This may be at the distal end of channel  30 , or may extend slightly inward or outward therefrom. 
     A further embodiment is shown in  FIGS. 6-7  and is similar to that described in  FIGS. 4-5 , but integrally forms the guide channel mechanism  60  as a fixed part of guide channel  30 .  FIG. 6  shows the guide channel mechanism  60  with the cable tie, showing capture of both the top and bottom edges of the cable tie head.  FIG. 7  shows an enlarged view illustrating the positive engagement of the mechanism with both top and bottom edges of the cable tie head. In this embodiment, top wall  32  of guide channel  30  is modified to have its distal end include a ramped surface  62 ′ (better shown in  FIG. 7 ) and a substantially perpendicular retention wall surface  64 ′ as illustrated. Other than this change, operation remains as in the previous embodiment. 
     While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. The matter set forth in the forgoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.