Abstract:
A method and apparatus are provided for the automated wrapping of a bundle with a resilient stretchable film. The method comprises the steps of (i) unrolling a desired length of the film from a roll. The film has a first panel overlapping a second panel. The panels are interconnected at a sealed first end. (ii) Sealing a second end of the panels to bond them together by a second seal at the desired length. (iii) Cutting the film along the second seal to form a tube. (iv) Separating the first panel of the tube from the second panel by grasping film edges of each of the panels, whereby the tube may be opened. (v) Loading the tube in an opened position on an expandable frame, whereby at least a portion of the tube is accumulated in a folded condition on the expandable frame. (vi) Stretching the tube by expanding the expandable frame. (vii) Covering the bundle with the tube, by displacing the expandable frame towards the bundle, whereby the stretched tube is gradually released therefrom onto the bundle in a stretched resilient condition.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of U.S. patent application Ser. No. 10/968,096 filed on Oct. 20, 2004, now U.S. Pat. No. 6,978,587, which is a divisional of U.S. patent application Ser. No. 10/204,441, filed on Sept. 3, 2002, now U.S. Pat. Ser. No. 6,904,736. 
   The present application claims priority on International Patent Application No. PCT/CA01/00264, filed on Mar. 1, 2001, and on U.S. Provisional Patent Application No. 60/186,740, filed on Mar. 3, 2000. 

   FIELD OF THE INVENTION 
   The present invention relates to a method and an apparatus for automated wrapping of bundles and, more particularly, for the automated wrapping of generally rectangular bundles of varying size on four or five faces thereof. 
   BACKGROUND OF THE INVENTION 
   The products of the forest industry, e.g. lumber pieces, are customarily stored outdoors in piles for subsequent transportation. To keep lumber pieces relatively dry, bundles of lumber pieces are customarily covered to be. protected from weathering. In order for some of the lumber inherent humidity to evaporate, bundles are often covered on five surfaces, leaving the bottom surface uncovered, whereby condensation may escape. Bundles have also been covered on their four lateral side faces, thereby leaving the bottom and top surface open, such that further humidity may escape. This latter four-face wrapping configuration is used with bundles placed under a roof and is also used to bond bundles of lighter material together, such as pallets of plastic components. 
   U.S. Pat. No. 3,809,223, issued on May 7, 1974 to Kendall discloses a five-face wrapping method wherein a inverted bag of heat shrinkable film is disposed on a bundle and is heated to tightly bond with the bundle. A moisture absorbent layer is disposed between the top surface of the bundle and the heat shrinkable film, whereby excess humidity is absorbed. 
   Canadian Patent Applications No. 2,198,201 and No. 2,230,026, both having a priority date of Feb. 21, 1997 disclose a frame having an expandable throat portion through which bundles pass while being displaced on a conveyor. A plastic tube having a closed end is disposed on the throat portion of the frame with the closed end placed downstream with respect to the conveyor such as to cover the opening defined by the throat portion. The tube portion is generally folded in accordion on the throat portion, which is expanded to stretch the plastic tube It is noted that the plastic tube consist of a plastic film stretchable and resilient at room temperature. As the bundle passes through the throat portion, the closed end of the plastic tube is caught by the front end of the bundle. As the bundle advances, the tube is gradually released from the throat portion, thereby tightly bonding to the bundle as it resiliently regains its shape. Once the bundle is downstream of the throat portion, a cutting and sealing apparatus cuts and seals the open end of the tube, thereby fully enclosing the bundle therein. It is noted that a corresponding Application has been awarded a patent, namely U.S. Pat. No. 6,161,365, issued on Dec. 19, 2000, to Girard et al. and discloses the method described above for hermetically bagging material such as lumber pieces. It is also observed that the step of disposing the plastic tube on the frame involves manual intervention. 
   Canadian Patent Applications No. 2,240,062 and No. 2,277,565 disclose a wrapping machine and a related method, which describe moveable arms which hold opposed ends of a plastic film. The arms are pivotally mounted in order to fold the plastic film on the four lateral side surfaces and the top surface of a bundle, thereby leaving the bottom surface uncovered. Each arm also comprises a stapling mechanism for securing the film to the bundle. These patent applications are fully automated. 
   The use of resilient plastic film is advantageous as it ensures a tight bonding with the bundled items. Heat shrinkable film provides a similar tight bonding, but involves heating means and is thus not as convenient and more costly. It appears that packaging with resilient plastic film provides a cost efficient method and desirable results. Thus, it would be desirable to apply these polymer properties with four or five face wrapping of bundles. 
   SUMMARY OF THE INVENTION 
   It is a feature of the present invention to provide a fully automated wrapping apparatus using stretchable plastic film for wrapping bundles on at least four faces. 
   It is a further feature of the present invention to provide a fully automated method for dispensing bags from storing position to wrap bundles. 
   According to the above features of the present invention, from a broad aspect, there is provided a method for automated wrapping of a bundle with a resilient stretchable film. The method comprises the steps of: 
   (i) unrolling a desired length of the film from a roll, the film having a first panel overlapping a second panel, the panels being interconnected at a sealed first end; 
   (ii) sealing a second end of the panels to bond them together by a second seal at the desired length; 
   (iii) cutting the film along the second seal to form a tube; 
   (iv) separating the first panel of the tube from the second panel by grasping film edges of each the panels, whereby the tube may be opened; 
   (v) loading the tube in an opened position on an expandable frame, whereby at least a portion of the tube is accumulated in a folded condition on the expandable frame; 
   (vi) stretching the tube by expanding the expandable frame; and 
   (vii) covering the bundle with the tube, by displacing the expandable frame towards the bundle, whereby the stretched tube is gradually released therefrom onto the bundle in a stretched resilient condition. 
   According to a further broad aspect of the present invention, there is provided an apparatus for automated wrapping of a bundle. The apparatus comprises a table having a top surface. A dispensing roll of resilient stretchable film is adjacent a first end of the table. Gripping means translate on the top surface of the table for pulling the film from the dispensing roll to an extended position, wherein a desired length of the film is disposed on the table. Sealing and cutting means at the first end of the table are provided for sealing and cutting the film in the extended position from the dispensing roll, whereby the film forms a collapsed tube. At least first and second jaw means grasp corresponding side edges of the collapsed tube in the extended position and displace them apart, whereby the tube is in an opened position. The first and second jaw means dispose the tube on an expandable frame. Winding means on the expandable frame pull the tube from the opened position to an accumulated condition, wherein at least a portion of the tube is accumulated in folds around the expandable frame. Means are provided to displace the expandable frame to a film expanding position stretch the tube in the accumulated condition. Means are provided to move the expandable frame towards the bundle whereby an upper portion of the tube covers the bundle and the tube is gradually released thereon in a stretched resilient condition to generally cover at least four faces of the bundles. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention will now be described in detail having reference to the accompanying drawings in which: 
       FIG. 1  is a perspective view of the automated wrapping apparatus in accordance with the present invention; 
       FIG. 2  is a cross sectional view of film configurations to be used with the automated wrapping apparatus of the present invention; 
       FIG. 3  is an enlarged fragmented view of film handling assemblies in accordance with the present invention; 
       FIG. 4  is a further perspective view of the automated wrapping apparatus; and 
       FIG. 5  is a still further perspective view of the automated wrapping apparatus. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   According to the drawings and more particularly to  FIGS. 1 ,  4  and  5  an automated wrapping apparatus in accordance with the present invention is generally shown at  10 . For reference purposes, a set of X-Y-Z axes has been added to the perspective views of the automated wrapping apparatus. The automated wrapping apparatus  10  comprises a dispensing apparatus  11  and a stretching apparatus  12 , and spans over a motorized conveyor M upon which bundles B 1  and B 2  are displaced in the positive direction of the Y-axis. The bundle B 1  is illustrated in position to be wrapped on its four lateral faces and, if desired, on its top surface. As explained hereinafter, a specifically sized bag or tube will be dispensed, sealed and cut in the dispensing apparatus  11 , and will be opened, stretched and wrapped upon the bundle B 1  in the stretching apparatus  12 . Thereafter, the motorized conveyor M will be activated to move the wrapped bundle B 1  downstream of the automated wrapping apparatus  10 , while the bundle B 2  will be positioned to be wrapped. It is pointed out that the conveyor M may be positioned with respect to the automated wrapping apparatus  10  such that the bundles are fed thereto from either one of the negative Y-axis direction, the positive and the negative X-axis directions. 
   Referring in particular to  FIG. 1 , the dispensing apparatus  11  has a table  20  with a longitudinal channel  21  generally in the middle thereof. A pulling arm  24  is slidably disposed on the table  20 , and is engaged in the channel  21 , whereby it translates longitudinally upon the table  20 , i.e. in the Y-axis direction. The channel  21  may enclose a linear actuator, a rodless cylinder or the like in order to displace the pulling arm  24  and position it precisely upon the table  20 . The pulling arm  24  is also provided with an actuated gripping member (not shown). 
   A sealing and cutting device  22  is secured at a first end of the table  20 . A plurality of rolls of film  23  are disposed adjacent the first end of the table  20  in a dispensing position, whereby free ends of either one of the film rolls  23  are grasped by the actuated gripping member of the pulling arm  24  and pulled through the sealing and cutting device  22 . The pulling arm is stopped when a desired length of film has been pulled on the table  20 , according to the size of the bundles to be wrapped. Once the desired length of film is pulled on the table by the pulling arm  24 , it is sealed and cut by the sealing and cutting device  22 . The sealing and cutting device  22  is a known mechanism which applies heat to the film to create a sealed seam, and cuts the sealed seam such that both sides of the cut are sealed. Accordingly, both ends of the film that has been pulled by the pulling arm  24  will be sealed, namely the end engaged in the gripping member of the pulling arm  24  and the end that has been sealed and cut, whereby a tube or a bag is formed, as will be described below. 
   Referring now to  FIGS. 2A to 2F , cross sections of various rolls of pre-folded film to be used with the automated wrapping apparatus  10  are shown. The material of the film consists of known low density polymers which is stretchable and resilient at ambient temperature.  FIGS. 2A to 2D  illustrate plastic films which that will be formed in bags which will be inverted for covering the lateral faces and the top surface of the bundle, i.e. five-face wrapping, whereas  FIGS. 2E and 2F  depict films that will be formed in tubes for covering the lateral surface thereof, i.e. four-face wrapping. Each cross-section shows a top portion  3  and a bottom portion  4 .  FIGS. 2A and 2B  illustrate plastic films having a gusset  1 . The gusset  1 , when the bag covers the bundle, corresponds to the top surface thereof. The gusset  1  ensures that the bag will embrace the shape of the bundle.  FIGS. 2C and 2D  do not have a gusset, and thus the bag made therewith will have protruding ears emerging from two of the four edges of the top surface of the bundle. Furthermore,  FIGS. 2A ,  2 C and  2 E each show slits  2 . The slits  2  will cover a portion of the bottom surface of the bundle when the bag or tube will be engaged thereon. It is observed that the upper portion  3  of the bag/tube is in each case longer than the bottom portion  4  of bag/tube. 
   Referring now to  FIG. 3 , a length of film that has been pulled by the pulling arm  24  on the table  20  is generally shown in a cross-sectional view at  25 . It is noted that the film used in  FIG. 3  is the type depicted in  FIG. 2A . It is also noted that the free ends of the pulled film  25  extend over an edge surface  26  of the table  20 . The edge  26  of the table is adjacent the stretching apparatus  12 . 
   Returning now to  FIG. 1 , the stretching apparatus  12  of the automated wrapping apparatus  10  has a fixed structure comprising four vertical uprights  30 A,  30 B,  30 C and  30 D. A bottom transverse member  31 AB is secured to bottom ends of the vertical uprights  30 A and  30 B. For the clarity of the description, letters affixed to numbers such as vertical upright  30 A will designate a determined corner of the stretching apparatus  12 . Furthermore, transverse members extending from a corner to another will be affixed with the letters corresponding to both corners, for instance bottom transverse member  31 AB. Thus, a bottom transverse member  31 CD is located at an opposed side of the stretching apparatus  12 . Upper transverse members  32  connect the four vertical uprights  30 A to  30 D and are thus designated by  32 AB,  32 BC,  32 CD,  32 AD. However, the transverse member  32 AD is below the table  20  and is thus not shown. 
   Referring to  FIGS. 1 ,  4  and  5 , cylinders  33 A to  33 D are located at each corner of the stretching apparatus  12 . Rods  34 A to  34 D of the cylinders  33 A to  33 D are fixedly secured to the bottom transverse members  31 AB and  31 CD, at the corresponding corners. Housing portions  35 A to  35 D of the cylinders  33 A to  33 D, respectively, are moveable and may thus translate up and down on the rods  34 , i.e. in the Z-axis direction. A moveable frame  40  of rectangular shape is secured at its four corners  40 A,  40 B,  40 C and  40 D to the corresponding housing portions  35 A to  35 D. Consequently, the moveable frame  40  can move upward and downward, i.e. in the Z-axis direction, with respect to the vertical uprights  30 A to  30 D, when actuated by the cylinders  33 A to  33 D, respectively. The moveable frame consists of four channels,  41 AB,  41 BC,  41 CD and  41 AD. The channels  41 BC and  41 AD are C-cross sectioned and face each other, whereby guides  42 AB and  42 CD are disposed therein. 
   Also shown are rollers  43 AB,  43 BC,  43 CD and  43 AD secured to the moveable frame  40 , which are each idle and free to rotate, and wheels at opposed ends rotatively engaged in the vertical uprights  30 A to  30 D. The rollers ensure the smooth upward and downward translation of the moveable frame  40  upon the vertical uprights  30 A to  30 D when actuated by the cylinders  33 A to  33 D. 
   The guide  42 AB is fixed to the channels  41 AD and  41 BC, whereas the guide  42 CD is moveably engaged therein using known methods. Consequently, the guide  42 CD can translate in the Y-axis direction, which corresponds to the longitudinal direction of the bundle B 1 . 
   Film handling assemblies  50 A to  50 D are disposed on the guides  42 AB and  42 CD at the corresponding corners A to D. Referring to  FIG. 3 , the film handling assemblies  50 C and  50 D are shown in an enlarged view. For simplicity purposes, the film assembly  50 D will be described in detail. Thereafter, like numerals with varying affixed letter thereto will designate like elements. The film handling assembly  50 D has a bracket  51 D and a winder  52 D. The bracket  51 D forms an arcuate wall having a rear surface  56 D and a bearing surface  55 D idle and free to rotate therein. The winder  52 D is pivotally mounted to the film handling assembly  50 D by a pivot  53 D upon which a friction wheel  54 D is motorized, whereby the friction wheel  54 D may be actuated to pivot about the pivot  53 D to come into contact with the bearing surface  55 D. When the friction wheel  54 D is actuated to rotate, the bearing surface  55 D rotates therewith, in an opposed direction, as they are in operative contact. This is likewise for film handling assemblies  50 A to  50 C. 
   Returning now to  FIG. 1 , the film handling assemblies  50 B and  50 C may translate on the guides  42 AB and  42 CD, respectively. Accordingly, they may be motorized and/or electrically driven using known mechanisms to translate thereon. It is thus noted that the film handling assembly  50 A is fixed about the moveable frame  40 . The film handling assembly  50 B can translate on the guide  42 AB as described above, i.e. in the X-axis direction with respect to the moveable frame  40 . Furthermore, the film handling assembly  50 D can translate in the Y-axis direction with respect to the moveable frame  40  as the guide  42 CD is displaceable thereabout, as explained herein before. Finally, the film handling assembly  50 C may translate in both the X-axis and the Y-axis direction. In a preferred embodiment, the film handling assemblies  50 B,  50 C and  50 D are actuated by hydraulic cylinders as relatively substantial force will be required to stretch the bag or tube thereon as will be explained hereinafter. 
   A film opening arm  60 A is pivotally disposed at a free end thereof to the guide  42 AB. Similarly, a film opening arm  60 D is pivotally disposed at an end of the guide  42 CD at the corner D, as well seen in  FIG. 3 . The film opening arms  60 A and  60 D are symmetrically identical. Thus, for clarity, the film opening arm  60 D will be described in detail by referring to  FIG. 3 , and thereafter, reference to like numerals with an A affixed thereto, for instance in the drawings, will designate like elements of the film opening arm  60 A. The film opening arm  60 D is pivotally fixed to the guide  42 CD at pivot point  61 D. A cylinder  62 D, pivotally fixed at point  63 D, actuates the movement of the film opening arm  60 D to pivot it about the pivot point  61 D. The cylinder may be hydraulically, pneumatically or electrically driven. A first jaw  64 D is disposed on a carriage  65 D. The carriage  65 D can translate up and down the film opening arm  60 D by means of a linear actuator (not shown) . The first jaw  64 D is electrically driven to open and close to grasp a portion of film. A second jaw  66 D is secured to the film opening arm  60 D and is also driven to grasp film, but is fixed to the film opening arm  60 D as opposed to the first jaw  64 D. 
   As the elements of the dispensing apparatus  11  and of the stretching apparatus  12  and the relative movements thereof have been described, the wrapping method will now be explained in detail. 
   The bundle B 1  is upstream of the automated wrapping apparatus  10  and is conveyed towards it by motorized conveyor M. The length of the bundle B 1  may be measured with sensors (not shown) or all bundles may be of a generally standard length. In any event, the puling arm  24  is actuated to translate towards the sealing and cutting device  22 , and uses its gripping member to grasp a free end of a roll of film  23 . 
   The roll of film  23  is pre-folded in accordance with the desired type of package wrapping required, as explained above. For instance, assuming the film  23  shown in  FIG. 2A  is used, the free sealed end of film  23  is grasped by the pulling arm  24 , and then pulled in the positive Y-axis direction, until a determined length of film  23  is obtained. Thereafter, the sealing and cutting device  22  will seal the pulled film, thereby forming a sealing seam. The sealed seam will be cut in two by the sealing and cutting device  22 , such that a bag (using samples of  FIGS. 2A to 2D ) or a tube (using sample of  FIG. 2E  or  2 F) is formed, and the free end of the roll of film  23  is sealed. 
   As best seen in  FIG. 3 , the bag is in a folded and flat state and is positioned on the table  20  such as to project over the edge  26  thereof. The film opening arms  60 A and  60 D are generally vertical, whereby the first jaws  64 A and  64 D are face to face with the top portion  3  of the bag, which projects over the bottom portion  4 . The first jaws  64 A and  64 D are located at opposed ends of the flat bag, yet at a distance from the sealing seams thereof. For instance, the distance may be slightly less than half the width of the bundle B 1 . The first jaws  64 A and  64 D are actuated to grasp the top portion  3  of the bag. The grasping is facilitated by the fact that the top portion  3  projects over an edge of the bottom portion  4 . Accordingly, all types of films, as shown in  FIGS. 2A to 2F , have a top portion  3  overlapping over the bottom portion  4 . 
   Thereafter, the first jaws  64 A and  64 D will translate up by about an inch on the film opening arms  60 A and  60 D, respectively. The bottom portion  4  of the bag will then be accessible by the second jaws  66 A and  66 D, which will in turn be actuated to grasp the bottom portion  4 . Once the top and bottom portions of the bag are secured in the jaws, the first jaws  64 A and  64 D will move up the film opening arms  60 A and  60 D, respectively, to the position shown in  FIG. 1 , thereby opening the bag. The bag will thus define a rectangular shape opening. 
   Thereafter, the film opening arms  60 A and  60 D will be pivoted to reach a generally horizontal position.  FIG. 4  depicts the film opening arms  60 A and  60 D which have almost reached the horizontal positioning. The film opening arms  60 A and  60 D pivot in a relatively abrupt way, such that the bag  25  thereon gets inflated or displaced by the ambient air. 
   When the film opening arms  60 A and  60 D are horizontal, the opened bag will be resting against the rear surfaces  56 A to  56 D of the brackets  51 A to  51 D. The winders  52 A to  52 D are pivoted, whereby the bag will be squeezed between the friction wheels  54 A to  54 D and the bearing surfaces  55 A to  55 D, respectively. 
   Referring to  FIG. 3 , the friction wheels  54  will be rotated in the direction of arrows E. Thus, the bag will be pulled downward until the gusset  1  of the bag is unfolded (sample of  FIG. 2A ) and abuts the top edges of the brackets  51 A to  51 D. The lateral walls of the bag will be accumulated against the rear surfaces  56 A to  56 D of the brackets  51 A to  51 D, respectively, and will be randomly folded. When a tube is folded on the film handling assemblies  50 A to  50 D, a portion will be left unfolded, such as to form a throat portion to be caught on the bundle during the wrapping thereof. For instance, about 4 inch (10 cm) can be left unfolded. 
   The film handling assemblies  50 B,  50 C and  50 D will then move in the X-axis and Y-axis direction accordingly, as explained above, to stretch the bag. The X-axis and Y-axis movement of the film handling assemblies  50 B,  50 C and/or  50 D will be stopped when the top of the bag has been stretched to be of greater dimension than the top surface of the bundle B 1 . Typically, a bag or tube is 6% to 15% shorter than the bundle to be wrapped and thus will be stretched by about 15% to 40% to be put on the bundle. 
   Thereafter, the moveable frame  40  will move downward in the Z-axis direction. Consequently, the top of the bag  25  will abut the top surface of the bundle B 1 . As the moveable frame  40  moves downward, the lateral walls of the bag, which are folded at a base of the brackets  51 A to  51 D, will be released gradually and will resiliently move against the lateral surfaces of the bundle B 1  to form a tight bond therewith. Referring to  FIG. 5 , the moveable frame  40  is shown moving downward on the lateral surfaces. 
   The moveable frame  40  is enabled to move further downward and below the rollers of the conveyor M, such that the bag will be completely released from the film handling assemblies  50 A to  50 D and will completely wrap five surfaces of the bundle B 1 . At this point, the bundle may either be moved outward from the automated wrapping apparatus  10  in the positive Y-axis direction, or the moveable frame  40  may be moved back to its initial position adjacent the table  20 , and this will be followed by the outward movement of the bundle B 1 . It is noted that if films depicted by  FIGS. 2E and 2F  were used, the four lateral surfaces of the bundle B 1  would be wrapped while the top and bottom surfaces would be generally uncovered. The bundle B 2  may then be displaced below the automated wrapping apparatus  10  to be wrapped according to the above described method. An advantage of the automated wrapping apparatus resides in the fact that a second tube or bag may be prepared on the table  20  as soon as a first bag is disposed on the moveable frame  40 . Consequently, precious process time is saved by overlapping these steps. 
   It is readily understood that the actuated members of the automated wrapping apparatus  10 , for instance sensors, linear actuators, hydraulic cylinders, are all connected to a central processing unit if required, such as a computer. Consequently, the actuated members are sequentially actuated for the optimal operation of the automated wrapping apparatus  10 . Also, the specifications of the bundles to be wrapped may be programmed in the central processing unit or may be determined on site by sensors and the like. 
   The automated wrapping apparatus  10  may serve various uses. Bundles of varying size and loaded pallets may be wrapped thereon as the resiliency of the bag or tube ensures the tight and embracing covering and packaging thereof. 
   It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims.