Abstract:
A refeed system for use in a strapping machine for feeding a strapping material around a load, positioning, tensioning and sealing the strapping material around the load. The refeed system refeeds strapping material into feed elements. The refeed system includes a driven, rotatable boost wheel having a first diameter when in a stationary mode and a second, larger diameter when in a second, rotating mode and an idler element opposite of the boost wheel. When the boost wheel is in the stationary mode, a first gap is defined between the boost wheel and the idler element to permit the free conveyance of strap through the gap and when the boost wheel is in the second rotating mode a strap, positioned in the gap is engaged by the boost wheel and is conveyed through the gap.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to a strapping machine refeed system. More particularly, the present invention is directed to a centrifugal boost wheel in a strapping machine refeed system to refeed strap following a strap error or fault. 
   Strapping machines are well known in the art for securing straps around loads. One type of known strapper is a stationary unit that includes a strapping head or weld head and drive mechanism mounted within a frame. A chute is mounted to the frame, through which the strapping material is fed. In a typical arrangement, a table-top or work surface is likewise mounted to the frame. 
   In a typical stationary strapper, the chute is mounted from about the work surface, and the strapping head is mounted below the work surface. Strap is fed from a source or dispenser to the strapping or weld head. The strapping head provides a number of functions. First, it provides structure to grip portions of the strap during the course of a strapping operation. The strapping head also includes a cutter to cut the strap from a strap source or supply. Last, the strapping head includes a sealer to seal an overlying course of strapping material onto itself. This seal is commonly referred to as a weld and is effected by heating overlying courses of the strap by use of a vibrating element or a heated element. 
   The feed system includes a pair of feed and tensioning or retraction wheels to feed the strap through the strapping head and chute and back to the strapping head, to pull the strap from the chute to around the load and to tension the strap around the load. The strapping machine can also include a winder or tensioning element to “pull” a greater tension in the strap. Typically, the winder is positioned in the feed system. 
   To permit efficient operation of the strapping machine and the overall strapping process, the strapping machine can be fully automated or substantially fully automated. 
   In the event a strap error occurs, the faulted strap is ejected from the feed system. In order reduce required operator attention, an automatic refeed is used to refeed the strap to the strapping head (to the feed wheels). Known automatic refeed systems include complex arrangement having a pair of rotating elements, one of which pivots toward and away from the other depending upon the presence or absence of strap between the elements. While these known systems function well, in order to maintain the systems optimally functioning, significant set-up and maintenance is required. In addition, when the strapping machine is operating in a mode in which high tension is required, the strap is pulled around the re-feed element, thus necessitating a relatively complex strap path arrangement. 
   Accordingly, there is a need for a strapping machine having a strap feeding and tensioning system with automatic refeed of the strap material. Desirably, such a system automatically refeeds the strap into the strapping head using elements that can remain present in the strap path during normal strapping operation. 
   BRIEF SUMMARY OF THE INVENTION 
   A refeed system is for use in a strapping machine of the type for feeding a strapping material around a load, positioning, tensioning and sealing the strapping material around the load. The refeed system automatically refeeds the strap into the strapping head using elements that remain present in the strap path during normal strapping operation. 
   The feed system includes a pair of feed elements for feeding the strapping material into strapping machine. The refeed system is configured to refeed strapping material into the feed elements and includes circumferentially expanding means for engaging the strapping material and conveying the strapping material to the feed elements when in a first state and for permitting free movement of the strapping material when in a second state. A present circumferentially expanding means is configured as a driven, rotatable boost wheel having an axis of rotation and having a first diameter when in a stationary mode (the first state) and a second, larger diameter when in a second, rotating mode (the second state). An idler element is positioned opposite of the boost wheel. The boost wheel is mounted to a motor for driving the wheel. 
   When the boost wheel is in the stationary mode, a first gap is defined between the boost wheel and the idler element to permit the free conveyance of strap through the gap. When the boost wheel is in the second rotating mode a strap, positioned in the gap is engaged by the boost wheel and is conveyed through the gap. The axis of rotation of the boost wheel remains fixed when the boost wheel is in the first and second positions. 
   In a present system, the boost wheel has a hub having a pair of opposing shoes mounted thereto. The shoes are movable between first and second positions to define the first and second diameters. The shoes are movable from the first position to the second position by rotation of the boost wheel. 
   Preferably, each shoe has a first end and a pivot pin at the first end for pivoting movement between the first and second positions. The shoes can include a slotted opening at a second end for receiving the pivot pin of the other shoe. In this manner, the pivot pin resides in the slotted opening and defines a stop to stop movement of the shoe beyond the second position. 
   The shoes have an outer periphery that defines a circle when in the first position and substantially defines an oval shape in the second position. To readily accommodate both the pivot and stop functions at each pivot pin, the first end of each shoe is bifurcated, defining a slot between the bifurcations such that the second end of the other shoe fits within the slot. A strapping machine having the refeed system is also disclosed. 
   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 front view of an exemplary strapping machine having a centrifugal boost wheel embodying the principles of the present invention; 
       FIG. 2  is an enlarged, partial view of the feed system shown in the operating position and with a section of strap material traversing through the feed system; 
       FIG. 3  is a view similar to that of  FIG. 2  with the strap guide open to access the strap feed path; 
       FIG. 4  is an enlarged, partial front view of the feed system showing a winder, an idler wheel and the boost wheel in the strap feed path; 
       FIG. 5  is a side view illustrating the boost wheel and winder and their respective motors; 
       FIG. 6  is a perspective view of the boost wheel and motor; 
       FIG. 7  is an exploded view of the boost wheel and motor; and 
       FIGS. 8A and 8B  illustrate the boost wheel in the stationary or retracted condition ( FIG. 8A ) and the rotating or feed condition ( FIG. 8B ), the wheel being shown with only one of the shoes mounted to the wheel hub for ease of illustration. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the present invention is susceptible of embodiment in various forms, there is shown in the figures 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 the 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 to  FIG. 1  there is shown a strapping machine  10  having a centrifugal boost wheel  12  embodying the principles of the present invention. The illustrated machine  10  is a bottom-seal strapper, meaning that the strapping head (or sealing head  14 ), which forms the seal of the strap S onto itself is at the bottom of the area  16  into which the load L is positioned for strapping. The strapper  10  includes, generally, the strapping or sealing head  14 , a feed system  18  and a strap chute  20 . A frame  22  supports the various elements of the machine  10 . A dispenser  24  supplies the strap material S to the strapper  10  via the feed system  18  to a feed head  26 . 
   In a typical configuration, the strap S is fed into the strapper  10  at the feed head  26  and is directed through sealing head  14  and into the bottom leg  28  of the strap chute  20 , around the chute  20  and back to the sealing head  14 . Once the strap S reenters the sealing head  14 , a free end of the strap S is held or secured, the feed end is tensioned around the load L, and the overlapping strap courses are sealed to one another as the feed end is severed from the supply. The load L is then discharged from the machine  10 . 
   In the course of a cycle of machine  10  operation, as the strap S is retracted and tensioned around the load L, it is pulled from the strap chute  20 . Tension is further applied by a winder  30 . The winder  30  is a rotating element that has an outer or peripheral strap path  32  and a central strap channel  34 . During feed and retraction cycles, the strap S traverses through the central strap channel  34  to the feed head  26 . During the tensioning cycle, the winder  30  is actuated (rotated) such that the strap S winds around the peripheral path  32  of the winder  30  to draw tension in the strap S. When the strapping cycle has finished, the winder  30  “unwinds” to unwrap the strap S from the winder  30  and to align the central strap channel  32  with the strap path (indicated generally at  36 ). An exemplary winder  30  is illustrated and described in Bell Jr. et al., U.S. Pat. No. 6,708,606, which is commonly assigned with the present application and is incorporated herein by reference. 
   At times during the strapping cycle, strap jams may occur, or other types of strap misfeeds may occur that pull the strap rearward beyond the feed wheels  38 ,  40 . In order to automatically refeed the strap S (so that operator attention is minimized or eliminated) the strap S must be refed to the feed wheels  38 ,  40 . 
   The present centrifugal boost wheel  12  provides just such boost or push for the strap S during refeed without interfering with movement of the strap S through the feed system  18  during normal operations, e.g., the feed, retraction and tension cycles. The boost wheel  12  includes a hub  42  having front and rear walls  44 ,  46  and a pair of opposing, movable shoes  48  mounted to the hub  42 . The hub  42  is mounted to a motor  50  (at the motor shaft  52 ), by for example, a spacer  53  or other element. In this manner, the motor  50  can be mounted to a rear side of the strapper (strapping head) support plate  54  to further increase access to the strap path  36 . The motor  50  is fixedly mounted to the plate  54  and thus the rotational axis A 42  of the hub  42  is fixed. 
   The shoes  48  have an outer or peripheral circular profile (see  FIG. 8A ) and are pivotally mounted to the hub  42  at a pivot points  55 , by pivot pins  56 , that are spaced from the central axis A 42  of the hub  42 . As the wheel  12  rotates, the centrifugal force forces (or urges) the shoes  48  outward, away from the center or central axis A 42  of the hub  42 . Because the shoes  48  are mounted to pivot pins  56 , the shoes  48  will pivot outwardly from the hub  42 . As the shoes  48  pivot outwardly, they create a pseudo expanded diameter d b  (see  FIG. 8B ) of the hub  42 , effectively simulating a larger diameter wheel  12 . 
   An idler wheel  58  is positioned opposite of the boost wheel  12  in the strap path  36 . As such, as the shoes  48  pivot outwardly the shoes  48  pinch the strap S between the boost wheel  12  and the idler wheel  58 . Sufficient friction is developed such the strap S is urged along the strap path  36  to the feed wheels  38 ,  40 . Because the strap S is fairly free to move through the strap path  36 , the amount of friction that the boost wheel  12  needs to develop to convey the strap S to the feed wheels  38 ,  40  (into the nip  60  between the feed wheels  38 ,  40 ) is relatively small. 
   The outward distance that the shoes  48  can pivot is limited by stop means  62 . In a present arrangement, the stop means  62  is provided by a notched opening  64  in an opposite end  66  of the shoe  48  (opposite of the pivot  55 ) that receives the other shoe&#39;s pivot pin  56 . In this manner each pivot pin  56  serves as a pivot  55  for one shoe  48  and a stop  62  for the other shoe  48 . This reduces the number of parts overall that are needed and simplifies the design of the wheel  12 . In a present embodiment, the pivot side  55  of the shoe  48  is bifurcated (as indicated at  68 ) and the stop or movable side  66  of the shoe  48  fits into a slot  70  in the bifurcated end  68  of the shoe  48 .  FIGS. 8A and 8B  show the wheel  12  with one shoe  48  (for ease of illustration) in the first position which is a stationary or non-rotating mode ( FIG. 8A ) and in the second position which is the rotating or boost mode ( FIG. 8B ), with the wheel rotating in the direction shown. The stationary diameter of the wheel  12  is indicated at d, and the boost diameter of the wheel  12  is shown at d b . When in the boost position, the profile of the wheel including both of the shoes  48  pivoted outwardly, is about an oval, which effectively presents the expanded diameter d b . 
   The present boost wheel  12  has a number of advantages over prior refeed arrangements. As will be appreciated from the figures, it is a simple design, but still provides a sufficient boost to move the strap S into the feed wheels  38 ,  40  (the nip  60  between the wheels) to allow the feed wheels  38 ,  40  to convey the strap S to the strapping head  14 . In addition, the boost wheel  12  is self-actuating. That is, only rotation of the wheel  12  is required to engage the wheel  12  with the strap S. No springs or other elements are needed to move the shoes  48  outwardly (to the second position) to engage the strap S, nor to return the shoes  48  to the first position or the free strap conveyance position. 
   Moreover, the wheel  12  is self-regulating. That is, the movement of the shoes  48  does not have to be adjusted to accommodate strap S of differing thicknesses. Rather, the shoes  48  will pivot outwardly only so far as the thickness of the strap or the stops  62  will permit. In addition, because of the simple, self-actuating design, the wheel  12  permits greater access to the strap path  36  and does not interfere with or disrupt the flow of strap S to and from the slack box  76  during normal feed and tension operations. 
   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 all such modifications as fall within the scope of the claims.