Patent Document

BACKGROUND OF THE INVENTION 
   The present invention relates to a tool head for use with an automatic cable tie installation system and, more particularly, to an automatic tie tool head including an anti-jam tensioning gear mechanism providing improved performance and reliability. 
   As is well known to those skilled in the art, cable ties are used to bundle or secure a group of articles such as electrical wires or cables. Cable ties of conventional construction include a cable tie head and an elongate tail extending therefrom. The tail is wrapped around a bundle of articles and thereafter inserted through a passage in the head. The head of the cable tie typically supports a locking element which extends into the head passage and engages the body of the tail to secure the tail to the head. 
   Although cable ties are often installed manually, it is desirable in certain applications to utilize an automatic cable tie installation system wherein cable ties are dispensed from a remote dispenser, and thereafter delivered to a tool head for application about a bundle of wires positioned within the jaws of the tool head. Automatic cable ties installation systems are well-known in the art, and are disclosed for example in U.S. Pat. Nos. 6,279,620, 4,790,225, 4,498,506 and 3,946,769. It will be appreciated that the disclosed tool heads include a plurality of subassemblies each having multiple moving parts, the subassemblies cooperating together to deliver, tension and cut the cable tie. To be commercially practical, the tool head must be capable of repeatedly applying a cable tie about the bundle of articles inserted within the jaw assembly without jamming. The tool head must also be able to complete a cycle (wherein one cable tie is wrapped, tensioned and cut) within a sufficiently short interval of time. 
   Those skilled in the art will appreciate that prior art tool heads can experience internal jams with respect to the tensioning/strap ejection portion of the tool head. More particularly, the tail of the installed tie, once severed from the bundled wires (after tensioning of the cable tie), is directed into an exit chute whereby the excess tail portion may exit the tool head. There are times, however, when the severed tail, rather than being directed into the exit chute, is misdirected under the guide ramp defining the leading edge of the exit chute. This then squeezes the severed tail between the guide ramp (which is a fixed portion of the tool head) and the rotating tension gear, thus causing a jam within the tool head. 
   There is therefore a need in the art for an automatic tie tool head which is capable of repeatedly tensioning a cable tie, severing the excess tail portion from the tensioned tie, and thereafter ejecting the severed tail portion without risk of the severed tail portion becoming jammed in the tool head. 
   SUMMARY OF THE INVENTION 
   The present invention, which addresses the needs to the prior art, provides a tool head for installation of a cable tie about a bundle of elongate articles. The tool head is adapted for use with a remote dispenser, cable tie bandolier and cable tie delivery hose of an automatic cable tie installation system. The cable tie includes a head and an elongate tail extending therefrom. The tail of the tie has a width T. 
   The tool head includes a housing. The tool head further includes a jaw assembly for grasping and directing the cable tie about the articles. The tool head also includes a tie passage communicating at one end with the cable tie delivery hose and at the other end with the jaw assembly whereby a cable tie supplied by the remote dispenser is delivered to the jaw assembly. The tool head additionally includes a tie tensioning assembly for tensioning the cable tie. The tie tensioning assembly includes a drive train and a pawl gear mechanism. 
   Finally, the pawl gear mechanism includes a tension gear having at least one tail-engaging surface extending thereabout. The tail-engaging surface has a width R and defines a circumference C 1  having a diameter D 1  with respect to the center of the tension gear. The pawl gear mechanism also includes a tie guide cooperating with the tension gear to define a first passage. The tie guide includes a second passage communicating with and extending between the first passage and the housing. The first passage is sized to receive the tail of the tie from the jaw assembly upon installation of the tie about the elongate articles. The pawl gear mechanism further includes a first auxiliary ramp located adjacent the tail-engaging surface. The width T of the tail is greater than the width R of the tail-engaging surface whereby the tail contacts the first auxiliary ramp as the tail moves therepast. The first auxiliary ramp has a leading edge defining a circumference C 2  having a diameter D 2  with respect to the center of the tension gear. The diameter D 2  is less than the diameter D 1  whereby the first auxiliary ramp guides the tail from the first passage into the second passage. 
   As a result, the present invention provides a tool head for use with an automatic cable tie installation system with is capable of repeatedly tensioning a cable tie, severing the excess tail portion of the tension tie, and thereafter ejecting the severed tail portion without risk of the severed tail portion becoming jammed in the tool head. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a prior art automatic cable tie installation system; 
       FIG. 2  is an exploded perspective view of a prior art tool head; 
       FIG. 2   a  is an enlarged detail of  FIG. 2 ; 
       FIG. 3  is an enlarged sectional view of a portion of the pawl gear mechanism of the prior art tool head of  FIG. 2 ; 
       FIG. 3   a  is an enlarged detail of  FIG. 3 ; 
       FIG. 4  is an exploded perspective view of the pawl gear mechanism shown in  FIG. 3 ; 
       FIG. 4   a  is an enlarged detail of  FIG. 4 ; 
       FIG. 5  is a perspective view of an automatic cable tie installation system in accordance with the present invention; 
       FIG. 6  is an exploded perspective view of the components of the pawl gear mechanism of the present invention; 
       FIG. 6   a  is an enlarged detail of  FIG. 6 ; and 
       FIG. 7  is an enlarged sectional view of a portion of the pawl gear mechanism of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, a prior art automatic cable tie installation system  10  is shown in  FIG. 1 . Installation system  10  includes a cable tie dispenser  12  (as described in commonly-owned U.S. Pat. No. 6,082,577, incorporated herein by reference), a cable tie bandolier  14  (as described in commonly-owned U.S. Pat. Nos. 5,934,465 and 5,967,316, incorporated herein by reference), a cable tie delivery hose  16  and a tool head  18 . In operation, dispenser  12  severs the leading cable tie from bandolier  14 , and thereafter propels the individual cable tie to the tool head via hose  16 . The cable tie is wrapped about a bundle of articles positioned within the jaws, tensioned and is then subjected to a cutting operation whereby the excess tail portion of the cable tie is cut from the tensioned tie. 
   The operating components of prior art tool head  18  are shown in  FIGS. 2 and 2   a . In this regard, the general operation of tool head  18  is well known to those skilled in the art. As discussed hereinabove, U.S. Pat. Nos. 6,279,620, 4,790,225, 4,498,506 and 3,946,769, all of which are incorporated herein by reference, disclose the structure and operation of various prior art tool heads. 
   As will be appreciated by those skilled in the art, the housing of tool head  18 , i.e., housing  52 , is preferably formed from first and second cooperating shells  54   a ,  54   b . Tool head  18  also includes jaw assembly  56 , tie tensioning assembly  58 , and a tie passage  60  communicating at one end with cable tie delivery hose  16  and at the other end with jaw assembly  56  whereby a cable tie supplied by remote dispenser  12  is delivered to the jaw assembly. 
   Jaw assembly  56  includes in particular a top jaw  62 , a bottom jaw  64 , opposing jaw-mounting plates  66   a ,  66   b , a trigger  68  connected to bottom jaw  64  for moving the bottom jaw between an open position and a closed position, a push rod  70  for moving top jaw  62  during installation of the cable tie about the bundle of elongate articles, a power-operated device  72  for powering said push rod, and a cutting mechanism  73  supported between jaw-mounting plates  66   a ,  66   b.    
   Tie tensioning assembly  58  includes in particular a drive train  74 , a pawl gear mechanism  76  and a tension adjustment mechanism  78  pivotable about a pivot point  80 . Cutting mechanism  73  cooperates with pawl gear mechanism  76  to cut off the excess tail portion from the tensioned tie. 
   In turn, drive train  74  includes a power-operated device  82 , a driveshaft  84  coupled at one end to power operated device  82 , a driveshaft bearing for supporting the other end of driveshaft  84  positioned within a housing  86 , and a gear assembly  88 . In turn, gear assembly  88  includes a first bevel gear  90  positioned at the end of the driveshaft  84 , a second bevel gear  92  fixedly coupled to a shaft  94  and located to engage first bevel gear  90 , a drive gear  96  also fixedly coupled to shaft  94 , a pair of opposing bearings  98  for rotatably supporting shaft  90 , and an idler gear  100  rotatably coupled to a shaft  102  via a bearing  104  and located to cooperate with the pawl gear mechanism  76 . As a result, rotary motion may be transmitted from driveshaft  84  to tension gear  105  (shown in hidden line in  FIG. 2   a ) of pawl gear mechanism  76 . 
   Gear assembly  88  further includes a pair of opposing gear-supporting plates  106   a ,  106   b , for supporting the mentioned gears therebetween. In this regard, each of plates  106   a ,  106   b  includes an aperture  108  sized to receive bearings  98 , and an aperture  110  sized to receive the end of shaft  102 . A microswitch  112  for sensing the presence of a cable tie is mounted on a bracket  114 , which in turn is secured to gear-supporting plate  106   a . Gear-supporting plates  106   a ,  106   b  also pivotally support pawl gear cut-off mechanism  76  via a pair of pivot pins  116 . Each of gear-supporting plates  106   a ,  106   b  include a pair of apertures  118  sized to receive the ends of pivot pins  116 . 
   Prior art pawl gear mechanism  76  is shown in detail in  FIG. 3 . In particular, tail  120  of the cable tie which is wrapped about the bundle of articles positioned within the jaws (not shown) is captured within a first passage  122  defined between tension gear  105  and the inside surface  124  of front tie-guide  126 . Tension gear  105  includes a plurality of teeth  128  extending thereabout. Each of the teeth is preferably configured to contact and engage the tail of the tie throughout first passage  122 . In this regard, first passage  122  is configured such that the distance between the inside surface  124  of the front tie guide and tip  130  of one of the teeth is less than the thickness Y of tail  120 . 
   As tension gear  105  rotates clockwise (as depicted in  FIG. 3 ), tail  120  is pushed towards a second passage, i.e., exit chute  132 . Ideally, tail  120  is directed into exit chute  132  (once it is severed from the tensioned cable tie) via ramp  134  located at the leading end of upper tie guide  136 , thereby pushing the previously cut tail (i.e., tail  138 ) out of the tool head. 
   However, in practice, tip  140  of tail  120  may, upon encountering the trailing end of tail  138 , be misdirected under ramp  134  (see  FIG. 3   a ). Although misdirection may occur when tip  140  encounters the trailing end of tail  138 , it is believed that tip  140  may also be misdirected between ramp  134  and tension gear  105  due to other factors such as variations in the individual ties, tolerances of the tool head and/or waste or debris caught in the tool head. 
   As shown in  FIGS. 4 and 4   a , width Z 1  of prior art ramp  134  is approximately equal to width Z 2  of the teeth of tension gear  105 . It will be appreciated that ramp  134  must be spaced a slight distance from the teeth of tension gear  105  to allow rotation of such gear. As a result, tip  140  may not always be deflected into exit chute  134  as intended. In the configuration shown in  FIGS. 3–4 , the teeth of tension gear  105 , as well as ramp  134 , are approximately 1.8 times wider than tail  120 . 
   Referring now to  FIG. 5 , and as discussed hereinbelow, automatic cable tie installation system  200  of the present invention incorporates novel tool head  202 . In this regard, tool head  202  incorporates and utilizes a novel pawl gear mechanism  204 . In particular, pawl gear mechanism  204  includes a tension gear  206  having a tail-engaging surface, i.e., teeth  208 , extending thereabout (see  FIGS. 6 and 6   a ). Teeth  208  define a circumference C 1  having a diameter D 1  with respect to the center of tension gear  206 . 
   As shown, each of teeth  208  has a width R which is less than the width S of tension gear  204 . Width R of teeth  208  is preferably less than width T of tail  120 . In one preferred embodiment, width R of teeth  208  is approximately 0.7 times the width T of tail  120 . As a result, tail  120  overhangs teeth  208  as tail  120  is driven between teeth  208  and front tie-guide  210  during tensioning. 
   Pawl gear mechanism  204  further includes an upper tie-guide  212 , which together with tension gear  206  and front tie guide  210 , define a first passage  214  being sized to receive the tail of the tie from the jaw assembly upon installation of the tie about the elongate articles and a second passage, i.e., exit chute  216 , communicating with and extending between the first passage and the housing. First passage  214  is preferably configured such that the distance between the inside surface  218  of front tie guide  210  and the engagement surfaces of teeth  208  is less than the thickness Y of tail  120 . In this regard, each of the teeth is preferably configured to engage and grip the tail as it travels through the first passage. 
   Upper tie guide  212  includes a main ramp  220  and at least one, and preferably a pair, of auxiliary guide ramps  222  positioned on opposing sides of teeth  208 . Each of the auxiliary guide ramps preferably has a width U. In one preferred embodiment, the width T of tail  120  is substantially equal to the sum of width R of teeth  208  and widths U of the auxiliary ramps. As best shown in  FIG. 7 , auxiliary guide ramps  222  extend away from and radially inward of main guide ramp  220 , i.e., through a location inside of diameter D 1  defined by the circumference of teeth  208 . In particular, leading edges  224  of auxiliary guide ramps  222  define a circumference C 2  having a diameter D 2  with respect to the center of tension gear  206 , D 2  being less than D 1 . 
   Main ramp  220  is preferably located to define the intersection of the first and second passages. Main ramp  220  includes a leading edge  226  which defines a circumference C 3  having a diameter D 3  with respect to the center of tension gear  206 . In one preferred embodiment, auxiliary guide ramps  222  extend continuously from diameter D 2  to diameter D 3 . As a result, tail  120  (which is wider than gear teeth  208 ) will initially contact auxiliary guide ramps  222  and be directed onto main guide ramp  220 . Thus, the auxiliary ramps continuously and positively deflect the tail away from the tension gear and onto the main ramp defining the entrance of the exit chute. Of course, it is contemplated herein that auxiliary guide ramps may be discontinuous from main ramp  220  or upper tie guide  212  as long as such auxiliary guide ramps are located approximately along diameter D 1  and are configured to direct the tail into the exit chute. 
   It will be appreciated that the present invention has been described herein with reference to certain preferred or exemplary embodiments. The preferred or exemplary embodiments described herein may be modified, changed, added to or deviated from without departing from the intent, spirit and scope of the present invention, and it is intended that all such additions, modifications, amendment and/or deviations be included within the scope of the following claims.

Technology Category: 7