Abstract:
Wrapping apparatus comprises a dispenser, for dispensing stretched wrap film, which includes a first frame assembly, and a second frame assembly pivotally mounted upon the first frame assembly between a first closed position and second open position. A film roll spindle is mounted upon the second frame assembly along with a plurality of guide rollers, while upstream and downstream prestretch rollers are mounted upon the first frame assembly. When the second frame assembly is disposed at the second open position, the film roll spindle and guide rollers project outwardly in a tilted orientation such that the exchange of film rolls, and the threading of the film between the guide rollers and the prestretch rollers, is facilitated.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a wrapping apparatus comprising a dispenser for dispensing stretched wrap film for wrapping around a load. 
   BACKGROUND OF THE INVENTION 
   In prior art, specification U.S. Pat. No. 5,414,979 discloses a wrapping apparatus that includes a dispenser for dispensing stretched wrap film. The dispenser includes a first frame assembly and a second frame assembly. The second frame assembly is hinged to the first frame assembly so as to be able to be turned about a vertical hinge axis in relation to the first frame assembly. Further the dispenser includes a film roll holder for rotatably holding a film roll. The film roll holder is arranged in the first frame assembly in a substantially vertical position. In U.S. Pat. No. 5,414,979 the film roll holder is mounted in the first frame assembly. The dispenser also includes upstream and downstream prestretch rollers for engaging a first side of the film, which upstream and downstream prestretch rollers are mounted in the first frame. Further, the dispenser includes guide rollers for engaging the second side of the film in the near proximity of the upstream and downstream prestretch rollers. The guide rollers deflect and guide the film to follow a tortuous path around the guide rollers and the prestretch rollers. The guide rollers are mounted in the second frame assembly. Therefore, the second frame assembly can be moved between a closed position and an open position. In the closed position the second frame assembly is in a position in which the film roll spindle and the guide rollers are proximate and parallel with respect to the prestretch rollers. In the open position the guide rollers are moved with the second frame assembly about the vertical hinge axis so that a sidewards open gap is formed between the prestretch rollers and the guide rollers. 
   A problem arises in the situation when it is necessary to exchange or replace the film roll. In the prior art dispenser this is very time consuming and laborious, because the film roll holder always preserves its vertical orientation in the first frame assembly being stationary in the film dispenser. Further, film threading is difficult because the operator must insert his hand and fingers inside the dispenser in order to pull the film from the film roll located behind the prestretch rollers to the front side of the prestretch rollers. 
   Further, this problem becomes even worse in a wrapping apparatus of turntable type wherein it is desirable to encapsulate the film dispenser inside the inner space of the vertical box-like column wherein the dispenser is guided for vertical movement. Such a desirable column has a doorway through which the film roll exchange and film threading must be made. The inner space is narrow and there is only little space in the inner space to operate with hands and fingers for replacement of the film roll and for film threading. 
   OBJECTS OF THE INVENTION 
   The object of the present invention is to overcome the above-mentioned drawbacks. 
   Accordingly, it is an object of the present invention to provide a new and improved wrapping apparatus having a film dispenser which enables an easy and ergonomic film roll exchange and film threading between the guide and prestretch rollers of the film dispenser. 
   Another object of the present invention is to provide a new and improved wrapping apparatus, which will overcome the various operational drawbacks and disadvantages characteristic of the conventional wrapping apparatus. 
   SUMMARY OF THE INVENTION 
   The foregoing and other objects are achieved in accordance with the teachings of the present invention through the provision of a new and improved wrapping apparatus which comprises a dispenser for dispensing stretched wrap film, the film having a first side and a second side, the dispenser including a first frame assembly having a first base member; a second frame assembly having a second base member mounted to the first base member by a hinge having a substantially horizontal hinge axis, the second frame assembly being able to be tilted around the hinge axis; a film roll spindle for rotatably holding a film roll in the dispenser in a substantially vertical position, the spindle being mounted in the second frame assembly; upstream and downstream prestretch rollers for engaging the first side of the film, the upstream and downstream prestretch rollers being mounted in the first frame assembly; guide rollers for engaging the second side of the film in the near proximity of the upstream and downstream prestretch rollers for deflecting and guiding the film to form a tortuous path around the guide and prestretch rollers, the guide rollers being mounted in the second frame assembly. The second frame assembly is movable between a closed position and an open position. In the closed position the second frame assembly is in a position in which the film roll spindle and the guide rollers are parallel with respect to the prestretch rollers. In the open position the film roll spindle and guide rollers are tilted to an angle with respect to the prestretch rollers in order to enable film threading to an upwardly opening gap formed between the prestretch rollers and the guide rollers and to facilitate exchange of the film rolls. 
   Further, a new and improved wrapping apparatus is provided, comprising a turntable for rotatably supporting a load to be wrapped; a vertical box-like column having a wall defining a vertically elongated inner space inside the box-like column, and vertical guide means arranged in the inner space, said wall having a doorway with a door; a dispenser for dispensing stretched wrap film, the film having a first side and a second side, the dispenser being arranged in the inner space of the box-like column and guided therein for vertical movement by the vertical guide means. The dispenser includes a first frame assembly having a first base member; a second frame assembly having a second base member mounted to the first base member by a hinge having a substantially horizontal hinge axis, the second frame assembly being able to be tilted around the hinge axis; a film roll spindle of rotatably holding a film roll in the dispenser in a substantially vertical position, the spindle being mounted in the second frame; upstream and downstream prestretch rollers for engaging the first side of the film, the upstream and downstream prestretch rollers being mounted in the first frame; and guide rollers for engaging the second side of the film in the near proximity of the upstream and downstream prestretch rollers for deflecting and guiding the film to form a tortuous path around the guide and prestretch rollers, the guide rollers being mounted in the second frame. The second frame assembly is movable between a closed position and an open position. In the closed position the second frame assembly is in a position in which the film roll spindle and guide rollers are parallel with respect to the prestretch rollers. In the open position the film roll spindle and guide rollers are tilted to an angle with respect to the prestretch rollers in order to enable film threading to an upwardly opening gap formed between the prestretch rollers and the guide rollers and, and in which open position at least the upper end of the film roll extends through the doorway to the outside of the box-like column to facilitate exchange of the film rolls. 
   The invention has the advantage that the exchange of the film roll is made very easy as the second frame assembly is pivotally moved from its closed position to its open position such that the film roll spindle is moved from its vertical orientation and tilted outwardly so as to be easily accessible for the operator. Simultaneously with this pivotal movement of the second frame assembly, an upwardly open gap is formed between the prestretch rollers and the guide rollers and is readily accessible from above for film threading. 
   In an embodiment of the wrapping apparatus in the second position the second frame assembly is tilted so that the angle of the film roll spindle axis with respect to vertical direction is less than 90 degrees. 
   In an embodiment of the wrapping apparatus the dispenser comprises a releasable latch for releasably locking the second frame assembly and the first frame assembly together in the closed position. 
   In an embodiment of the wrapping apparatus the film roll spindle adapted to be inserted into the center hole of the film roll has a lower end mounted on the second base member the spindle extending from the second base member to a free upper end. 
   In an embodiment of the wrapping apparatus the second frame assembly comprises an upper member, and the guide rollers have an upper end mounted on the upper member and a lower end mounted on the second base member. 
   In an embodiment of the wrapping apparatus the dispenser comprises a motor for driving the prestretch rollers. 
   In an embodiment of the wrapping apparatus the guide rollers are idler rollers. 
   In an embodiment of the wrapping apparatus the guide rollers include a first guide roller, a second guide roller and a third guide roller which in the closed position of the second frame assembly are arranged so that the first guide roller is located upstream of the upstream prestretch roller, the second guide roller is located between the upstream prestretch roller and the downstream prestretch roller, and the third guide roller is located downstream of the downstream prestretch roller. 
   In an embodiment of the wrapping apparatus the dispenser includes means for detecting film tension, said means being arranged in the first frame assembly and located downstream of the third guide roller. 
   In an embodiment of the wrapping apparatus the means for detecting film tension comprises a spring loaded pendulum roller engaging the second side of the film, and a detector for detecting the rotational angle of the pendulum roller. 
   In an embodiment of the wrapping apparatus the wall of the box-like column comprises a vertical slot through which the film dispensed by the dispenser can be lead from the inner space of the column to the outside of the column to wrap the load. 
   In an embodiment of the wrapping apparatus in the open position at least the upper ends of the guide rollers extend through the doorway to the outside of the box-like column to expose the upwardly opening gap between the prestretch rollers and the guide rollers for film threading. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other objects, features, and attendant advantages of the present invention will be more fully appreciated from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views, and wherein: 
       FIG. 1  is a perspective view of the dispenser of the new and improved wrapping apparatus the second frame assembly being shown in a closed position; 
       FIG. 2  represents the dispenser of  FIG. 1  with the second frame assembly being tilted in an open position with respect to the first frame assembly; 
       FIG. 3  is a side view of the dispenser of  FIG. 1 ; 
       FIG. 4  is a perspective view of the new and improved wrapping apparatus seen from one angle; 
       FIG. 5  is a perspective view of the wrapping apparatus of  FIG. 4  seen from another angle during wrapping of a load; and 
       FIG. 6  represents a diagrammatic section VI—VI through  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 to 3  show a film dispenser  2  which is provided for dispensing stretched wrap plastic film (not shown) in a wrapping apparatus. 
   As can be seen from  FIGS. 1 ,  2  and  3  the dispenser  2  includes a first frame assembly  6  having a first base member  7  and a second frame assembly  8  having a second base member  9 . The second base member  9  is pivotally mounted to first base member  7  by a hinge  10  (in  FIG. 3 ). The hinge  10  has a substantially horizontal hinge axis  11 . The second frame assembly  8  can be tilted around the hinge axis  11  between a closed position I shown in  FIG. 1  and an open position II shown in  FIG. 2 . 
   Further, the dispenser  2  comprises a film roll spindle  12  which is adapted to hold a film roll  13  in the dispenser  2  in a substantially vertical position when it is ready for operation in the closed position I. In  FIG. 2  the film roll  13  is schematically drawn with broken lines. The spindle  12  allows free rotation of the film roll  13 . The spindle  12  is mounted on the second base member  9  in the second frame assembly  8 . The film roll spindle  12  is adapted to be inserted into the center hole  20  of the film roll  13 . The lower end  21  of the spindle  12  is mounted on the second base member  9  of the second frame assembly  8  wherefrom the spindle extends upwards to its free upper end  22 . 
   Further, the dispenser  2  includes an upstream prestretch roller  14  and a downstream prestretch roller  15 , which are driven by a motor  26  with a chain and sprocket drive at a preselected velocity ratio. 
   The prestretch rollers  14  and  15  may have a suitable coating of resilient nonslip material such as rubber to provide a sufficient friction gripping to the film. The prestretch rollers have different peripheral speeds so that the downstream prestretch roller  15  has a faster peripheral speed than the upstream prestretch roller  14  to stretch the film between the prestretch rollers  14  and  15 . In some applications it is desirable to stretch film over its yield point to plastically deform the film in the direction in which it is being dispensed. 
   The prestretch rollers  14  and  15  engage the first side  4  of the film  3 . The upstream and downstream prestretch rollers  14  and  15  are mounted in the first frame assembly  6 . 
   Further, the dispenser  2  includes guide rollers  16 ,  17  and  18 , which are idlers and engage the second side  5  of the film  3  in the near proximity of the upstream and downstream prestretch rollers  14  and  15  for deflecting and guiding the film  3  so that the film  3  forms a tortuous W-shaped path around the guid rollers  16 ,  17 ,  18  and the prestretch rollers  14  and  15  (see also  FIG. 6 ). The guide rollers  16 ,  17 , and  18  are mounted in the second frame assembly  8 . In the preferred example of  FIGS. 1 to 3  the guide rollers include a first guide roller  16 , a second guide roller  17  and a third guide roller  18 . In the closed position I of the second frame assembly  8  the guide rollers are arranged so that the first guide roller  16  is located upstream of the upstream prestretch roller  14 . The second guide roller  17  is located between the upstream prestretch roller  14  and the downstream prestretch roller  15 . The third guide roller  18  is located downstream of the downstream prestretch roller  15 . The second frame assembly  8  comprises an upper member  23 . The guide rollers  16 ,  17 ,  18  have their upper ends  24  mounted on the upper member  23  and lower ends  25  mounted on the second base member  9 . 
   As can be seen in  FIGS. 1 and 2  the second frame assembly can be moved between a closed position I and an open position II. In the closed position I of  FIG. 1  and which also can be seen in  FIG. 6 , the second frame assembly  8  is in a position in which the film roll spindle  12  and the guide rollers  16 ,  17  and  18  are parallel with respect to the prestretch rollers  14  and  15 . In the open position II of  FIG. 2  the second frame assembly  8  with its film roll spindle  12  and guide rollers  16 ,  17  and  18  are tilted to a suitable angle α with respect to the first frame assembly  8  and the prestretch rollers  14  and  15 . The purpose of this tilting operation is to enable the operator an easy access to the spindle  12  to facilitate exchange of the film rolls in the spindle  12  and also to enable an ergonomic and easy film threading to an upwardly opening gap which is formed between the prestretch rollers  14 ,  15  and the guide rollers  16 ,  17 ,  18 . The angle α of the film roll spindle axis with respect to vertical direction in the example of the  FIG. 2  is about 30 to 50 degrees but can be adjusted according to specific needs to any suitable angle less than 90 degrees. 
   Further, the dispenser  2  comprises a releasable latch  19  for releasably locking the second frame assembly  8  and the first frame assembly  6  together in the closed position I. 
   As can be seen in  FIGS. 1 ,  2  and  6 , the dispenser  2  further includes means for detecting film tension being arranged in the first frame assembly  6  and located downstream of the third guide roller. The means for detecting film tension comprises a spring loaded pendulum roller  27  which engages the first side  4  of the film  3 . A detector  28  is arranged for detecting the rotational angle of the pendulum roller  27 . The speed of the motor  26  is adjusted in relation to the angle detected by the detector  28 . 
     FIGS. 4 ,  5  and  6  show a wrapping apparatus  1  provided with the dispenser  2  disclosed above with reference to  FIGS. 1 to 3 . 
   The wrapping apparatus  1  includes a turntable  29  for rotatably supporting a load  30  to be wrapped as is schematically shown in  FIG. 5  . Further, the wrapping apparatus  1  includes a vertical box-like column  31  having a wall structure  32  which defines a vertically elongated inner space  33  inside the box-like column  31 . A vertical guide  34  means is arranged in the inner space  33  and attached to the back wall of the inner space  33 . The dispenser  2  is arranged in the inner space of the box-like column  31  and guided therein for vertical movement by the vertical guide means  34  as is shown in the section view, see  FIG. 6 . 
   The wall  31  has a doorway  35  provided with doors  36 . In  FIG. 4  the doors  36  are opened and the second frame assembly  8  is tilted to an angle in relation to the first frame assembly  6 . 
   The second frame assembly  8  is movable between a closed position I and an open position II as shown in  FIG. 4 . In the closed position I the second frame assembly  8  is in a position as shown in  FIG. 1 . 
   In the open position II as shown in  FIG. 2 and 4  the film roll spindle  12  and guide rollers  1  are tilted to an angle with respect to the prestretch rollers so that the film roll spindle  12  and at least the upper parts of the guide rollers  16 ,  17 ,  18  extend obliquely through the doorway  35  to the outside of the box-like column  31  to expose the upwardly opening gap between the prestretch rollers and the guide rollers for film threading and to provide ergonomic and easy access to the spindle  12  for exchanging the film rolls. 
   As can be seen in  FIGS. 4 to 6 , the wall of the box-like column  31  comprises a vertical slot  37  through which the film  3  dispensed by the dispenser  2  is led from the inner space  33  of the column  31  to the outside of the column  31  to wrap the load  30  as the load  30  is rotated by the turntable  29  to the rotational direction shown with arrow  38 . 
   Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.