Patent Publication Number: US-6990894-B2

Title: Strapping machine with self opening re-entry gates

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to an improved re-entry gate arrangement for a strapping machine. More particularly, the present invention is directed to a re-entry gate assembly for a strapping machine in which a pair of linked gates both open upon the urging open of either gate. 
   Strapping machines are used for securing straps around loads. One type of known strapper includes a strapping head and drive mechanism mounted within a frame. Strapping material is fed, for a supply (e.g., a dispenser) into the chute. A typical drive mechanism includes feed wheels that “push” the material through the chute via the strapping head. The leading end of the strapping material traverses the chute and re-enters the strapping head at the end of the chute. 
   The strap is then rewound and tensioned around the load, the overlying strap courses welded together and the trailing end of the strapping material severed or cut from the supply. During the rewinding and tensioning step, the strap is “pulled” from the chute. During the “pulling”, the force of the exiting strap opens one or more doors, gates or latches that facilitate removing the strap from the chute. 
   The point along the chute at which the strap exits the chute and re-enters the strapping head is at the re-entry gate assembly. A typical re-entry gate assembly includes opposing doors or gates that are independently urged open to permit the strap to pass from the chute. The gates must have sufficient resistance to stay closed to maintain the strap within the chute, but must also open as the strap exerts sufficient force (e.g., when pulled during re-winding), to the release the strap from the chute. 
   It has been found that, at times, strap does not release evenly across the face of the gates. In the event that the strap contacts one of the doors prior to, or with greater force than it contacts the other door, the strap can become caught on the gates and at the strapping head, thus causing machine malfunction. It has also been found that, due to the geometry of the cute, and gates, the frame and the load, the strap may not fully strip from the chute during tensioning. As such, again, the strap can become caught on the strapping head causing a machine malfunction. 
   Accordingly, there exists a need for a re-entry gate assembly for a strapping machine that permits ready re-entry of the strapping material into the strapping head, following traversal through the strap chute. Desirably, such a re-entry gate assembly prevents the strap from becoming caught at the chute and/or strapping head, during tensioning modes (as the strap is pulled from the chute). Most desirably, such a reentry gate assembly urges both gates open with the opening (pivoting) of the strapping head to assure release of the strapping material. 
   BRIEF SUMMARY OF THE INVENTION 
   A reentry gate assembly for a strapping machine permits ready re-entry of the strapping material into the strapping head, following traversal through the strap chute. Such a re-entry gate assembly prevents the strap from becoming caught as the strap exits the chute during tensioning mode (as the strap is pulled from the chute), and following opening of the strapping head, and thus prevents the strap from becoming caught as it exits the gate. 
   An exemplary strapping machine is of the type having a feed assembly, a chute and a strapping head. The strapping machine is configured to convey a strapping material into the strapping head, into and around the chute and to exit the chute and return to the strapping head. The strapping head is configured to receive first and second courses of associated strapping material, position, tension and seal the strapping material around a load. 
   The reentry gate assembly is positioned adjacent the strapping head in an opening in the chute. The reentry gate is configured to receive the strap as it return around the chute, introduce the strap back into the strapping head, and release the strap from the chute as the strap is tensioned or pulled to the load. 
   The reentry gate assembly includes a body having a strap path surface and first and second pivotable gates movable between a closed position in which the gates overly the strap path surface and define a strap pathway, and an open position in which the gates are pivoted away from the strap path surface. A link operably connects the first and second gates so that when strapping material present in the strap pathway with the gates closed is urged outwardly of the strap pathway, contact of the strapping material with either the first or second gate moves the link to open the other gate. In this manner, the gates open together with the opening of either gate. 
   In a preferred embodiment, the gates are biased to the closed position. A biasing element such as a spring can be disposed between each gate and the body to bias the gates to the closed position. 
   To facilitate connection of the gates, each gate includes a leaf portion overlying the strap path and a foot portion depending from the leaf portion. Each gate further includes a pivot disposed between the leaf portion and foot portion about which the gate pivots. Each foot portion extends toward the other foot portion and defines a link arm. The link operably connecting the gates extends between the link arms. Preferably, the link arms are on planes different from one another relative to the strap path surface and the link extends at an angle between the link arms. 
   A strapping machine having a frame, a chute, a strapping head and a reentry gate assembly is also disclosed. The reentry gate assembly includes a strapping head contact member or lever that, in cooperation with the strapping head, opens both gates upon opening (or pivoting open) of the strapping head. 
   These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
       FIG. 1  is a perspective view of an exemplary strapping machine having a self opening re-entry gate assembly embodying the principles of the present invention; 
       FIG. 2  is a perspective view the self opening re-entry gate assembly as viewed looking along the strap path, toward the weld head; 
       FIG. 3  is an exploded view of the re-entry gate assembly; and 
       FIG. 4  is a perspective illustration of the reentry gate mounted to the strapping head for cooperating movement, to open the gates upon opening of the strapping head. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
   It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
   Referring to the figures and in particular  FIG. 1 , there is shown a strapping machine  10  having a self opening re-entry gate assembly  12  embodying the principles of the present invention. The strapping machine  10  includes, generally, a frame  14 , a strap chute  16 , a feed assembly  18  and a strapping head or weld head  20 . A controller  22  provides automatic operation and control of the strapper  10 . 
   In operation, strap material is fed from a supply, such as a spool or dispenser (not shown). The strap is fed to (or pulled by) the feed assembly  18 , and is fed into and through the strapping head  20  into the chute  16 . The strap traverses around the chute  16  and re-enters the strapping head  20  at the re-entry gate assembly  12 . As set forth above, the re-entry gate assembly  12  is positioned at the end of the chute  16  and as such, re-feeds the strapping material into the strapping head  20 . 
   The strap end that re-enters the strapping head  20  (which end is referred to as the leading end of the strap) then moves into the strapping head. Once inside of the strapping head  20 , the leading end is gripped at a gripper and the trailing end is pulled or tensioned around the load. The tensioning action strips the strap from the chute  16  and positions the strap around the load L. The overlying courses of strapping material (inside the strapping head) are welded and the trailing end is cut to free the load L. The strapping head  20  anvil  21  (via pivoting movement of the strapping head side plate  23 ), then pivots out of the strap path and the strap is released from the strapping head  20 . Exemplary strapping heads are disclosed in Gerhart, U.S. Pat. No. 6,532,722 and Lopez, U.S. Pat. No. 6,543,341, both of which patents are commonly assigned with the present application and both of which are incorporated herein by reference. 
   The present re-entry assembly  12  serves a number of functions. First, it provides a re-entry point for the strapping material from the chute  16 , back into the strapping head  20 . As such it serves to direct the strap exiting the chute  16  into the strapping head  20 . In addition, the gate assembly  12  serves as the last point of contact of the strap as it is stripped or pulled from the chute  16 . That is, the strap is retained within the chute  16  by various guides and/or walls as the strap is conveyed through the chute  16 . These guides and/or walls are moved away from a strap supporting position (e.g., the guides/walls are pulled out from under the strap) as the strap is tensioned. This results in the strap being stripped from the chute  16  and positioned on or around the load L. 
   The re-entry gate  12  is the last position along the strap path (and is immediately adjacent the chute  16  end) from which the strap is stripped. To this end, it has been found that it is highly desirable for the strap to pull evenly from the gate  12 . That is, the plane of the strap should be perpendicular to the direction of movement of the strap toward the load (e.g., the strap should not skew as it is stripped from the chute  16 ). It has also been found that for certain loads and strapping conditions, the strap may not fully strip from the chute  16  (and from the reentry gate assembly) following tensioning and welding. To this end, problems have been encountered with the strap becoming hung-up or caught at the reentry gates after the strapping cycle has been completed. 
   The present re-entry gate assembly  12  includes first and second gates  24 ,  26 , respectively, that are linked to one another so that as either of the gates  24  or  26  is pulled or otherwise urged open, the other gate  26  or  24  opens. The reentry  12  includes a wedge-shaped body  28  having a surface  30  (the reentry surface) along which the strap traverses. The first and second gates  24 ,  26  are hingedly mounted to the body  28  to define an elongated, openable track, as indicated at  32 , through which the strap traverses. The strap enters the reentry  12  in the direction indicated by the arrow at  34 . 
   The gates  24 ,  26  are mounted so as to pivot open (as indicated by the arrows at  36 ) transverse to a plane P 30  defined by the strap path (e.g., generally transverse to a plane defined by the reentry surface). The gates  24 ,  26  each pivot about a pivot pin  38  that extends through openings  40  in the body  28  that lie on either side of the gate hinge  42 . In this arrangement, the gates  24 ,  26  pivot about axes A 24 , A 26  that are substantially parallel to the plane P 30  of the reentry surface  30 . 
   The gates  24 ,  26  are biased to the closed position (that is, overlying the reentry surface  30 ) to define the strap path  32 . In a present embodiment, a spring  44  is positioned between the body  28  the respective gates  24 ,  26 , at a lower or foot region  46 ,  48 , respectively, of the gate  24 ,  26  opposite of the gate leaf  50 ,  52 , respectively, relative to the respective gate hinges  42 . As seen in  FIG. 3 , the springs  44  urge the lower portions  46 ,  48  of the gates  24 ,  26  outwardly which in turn urges the gates  24 ,  26  to the closed position, thus maintaining the gates  24 ,  26  closed during normal operation, until the strap is stripped from the chute  16 . 
   The gates  24 ,  26  are operably connected to one another by a link  54 . The link  54  is connected to the respective gates  24 ,  26  at gate link arms  56 ,  58 , respectively. The gate link arms  56 ,  58  are inwardly oriented extensions formed from their respective gates  24 ,  26  at the gate foot portions  46 ,  48 . As best seen in  FIG. 2 , the link arm  56  for gate  24  is located at a plane P 56  that is below the pivot axis A 24  for gate  24 , whereas the link arm  58  for gate  26  is located at a plane P 58  that is above the pivot axis A 26  for gate  26 . In such an arrangement, the link  54  is positioned at an angle α as it extends between the arms links  56 ,  58 . To this end, the urging of either arm  56  or  58  results in a pushing motion or force (e.g., opening of gate  24  pushes gate  26  open) or in a pulling motion or force (e.g., opening of gate  26  pulls gate  24  open) through an arcuate paths. 
   Gate  26  also includes a release member or lever  60  extending from a side thereof. The lever  60  includes a roller  64  mounted to an arm  66  extending from gate  26 . The lever  60  is configured to cooperate with the strapping head  20  to open the gates  24 ,  26  when the strapping head  20  opens (pivots) to release the strap. To this end, as the strapping head  20  pivots open (that is, as the anvil  21  pivots open by movement of the head side plate  23 , as indicated by the arrow at  68 ), the side plate  23  contacts the lever roller  64  which urges the gates  24 ,  26  open. Thus, the strap is readily released from the gate assembly  12 , even if it did not release from the assembly  12  during tensioning. In addition, the lever  60  permits manually opening the gates  24 ,  26  (by urging gate  26  open) to, for example, clear any debris or clogs from the reentry. The gates  24 ,  26  can also include upturned entrances  62  that define slightly enlarged openings at the entry to the reentry assembly gates  24 ,  26 . This facilitates introduction of the strap into the reentry assembly  12 . 
   All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
   In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
   From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.