Patent Abstract:
A method of opening and closing a bag having a front and a rear and an opening at the top includes feeding the bag to a machine which holds an upper end of the front of the bag, moves the upper end of the rear of the bag rearwardly to partially open the bag clamps each opposite side of the bag while the bag is in the partially open configuration, and moves the clamped opposite sides of the bag and the rear of the bag rearwardly to a fully open position.

Full Description:
FIELD OF INVENTION 
     This invention relates to bag opening and closing machines, the bags usually but not necessarily being plastic bags. 
     BACKGROUND OF THE INVENTION 
     Machines for opening and closing bags are of course well known, see for example U.S. Pat. No. 4,124,966 (Wilson) issued Nov. 14, 1978 and U.S. Pat. No. 4,198,800 (Wilson) issued Apr. 22, 1980, the contents of these patents being hereby incorporated herein by reference. Such machines open plastic bags one at a time, fill the open bag with the necessary contents and then close the bag. However, especially with plastic bags, known machines do not open the bags as effectively as desired. 
     It is therefore an object of the invention to provide a bag opening and closing machine which has a more effective opening mechanism. 
     SUMMARY OF INVENTION 
     According to one aspect of the invention, a method of opening and closing a bag having a front and a rear and an opening at the top includes feeding the bag to a machine which: 
     a) holds an upper end of the front of the bag, 
     b) moves the upper end of the rear of the bag rearwardly to partially open the bag, 
     c) clamps each opposite side of the bag while the bag is in the partially open configuration, and 
     d) moves the clamped opposite sides of the bag and the rear of the bag rearwardly to a fully open position. 
     The bag may have a reclosable seal which remains in a closed configuration when the bag has been partially opened and which is opened by a plunger moving into the bag when the bag is being fully opened. 
     Each side of the body may be clamped by a clamping finger which moves into the bag adjacent the side thereof. Alternatively, each side of the body may be clamped between clamping jaws outside the bag. 
     According to another aspect of the invention, a bag opening and closing machine for bags having a front and rear and an opening at the top has: 
     a holder for holding an upper end of the front of the bag, 
     means for moving an upper end of the rear of the bag rearwardly to partially open the bag, 
     means for clamping each opposite side of the bag while the bag is in the partially open configuration, and 
     means for moving the clamped sides of the bag and the front of the bag rearwardly to a fully open position. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, of which: 
     FIG. 1 is a perspective view from the front of a bag opening and closing machine in accordance with one embodiment of the invention, 
     FIG. 2 is an enlarged perspective view of the portion of the machine where a supply of bags to be opened are hung, with one bag being shown in dotted outline, 
     FIG. 3 is a planned view of the machine with the suction cups in a forward position engaging the rear of a bag to be opened., 
     FIG. 4 is a similar view but with the suction cups having been moved rearwardly to slightly open the upper portion of the bag, with the rear clamps holding the upper edge portion of the rear of the bag in an initial rearward position, and with the side clamps holding the sides of the bag in laterally spaced positions, 
     FIG. 4 a  is an enlarged somewhat diagrammatic side view taken along the line  4   a — 4   a  of FIG. 4 showing the slightly open configuration of the bag, 
     FIG. 4 b  is an enlarged somewhat diagrammatic front view of one of the side clamps and associated portion of the bag, 
     FIG. 5 is a similar view to FIG. 4 but with the rear clamps having been moved rearwardly to more fully open the upper portion of the bag and the plunger having been moved downwardly to open the zip and the lower portion of the bag, 
     FIG. 6 is a similar view but with the rear clamps having been moved forwardly after filling of the bag, to nearly close the upper portion of the bag, 
     FIG. 7 is a planned view of a portion of the machine showing an alternative side clamping assembly with the jaws thereof in the open position, and 
     FIG. 8 is similar to FIG. 7 but showing the jaws in the closed position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, the upper bag opening and closing machine has a supply of plastic bags  12  to be filled hung one behind the other on forwardly extending bag receiving rods  14 ,  16  which pass through laterally spaced apertures  18 ,  20  in a flap  22  extending upwardly from the front of the bag  12 . The receiving rods  14 ,  16  are upwardly inclined so that the bags  12  slide rearwardly down the rods  14 ,  16 . A carriage  24  is mounted on a pair of laterally spaced and rearwardly extending rails  26 ,  28 , and the rails  26 ,  28  are mounted at the front and rear on laterally extending rails  30 ,  32  so that the carriage  24  can be moved laterally. 
     The carriage  24  has a front portion  36  which is fixed on the rails  26 ,  28  and laterally spaced middle portions  38 ,  39  and a rear portion  40  which are movable in a rearward direction. The middle portions  38 ,  39  are connected to the front portion  36  by transversely spaced links  42 ,  44  respectively whose opposite ends are pivotally connected to the front portion  36  and the respective middle portion  38 ,  39 . The links  42 ,  44  are laterally, outwardly and rearwardly inclined. The rear portion  40  is connected to the middle portions  38 ,  39  by two laterally spaced pairs of links  46 ,  48  and  50 ,  52  respectively. The opposite ends are pivotally connected to the rear portion  40  and respective middle portions  38 ,  39 . The links  46 ,  48  are laterally inwardly and rearwardly inclined, as also are the links  50 ,  52 . 
     The middle portion  38  of the carriage  24  carries a side clamping assembly which includes a side clamping finger  58  which is movable between inoperative and operative positions by a pneumatic cylinder  60 . Likewise, the middle portion  39  carries a side clamping finger  62  operable by a pneumatic cylinder  64 . The rear portion  40  carries a pair of laterally spaced longitudinally movable suction cups  66 ,  68  operable by pneumatic cylinders  70 ,  72  respectively and also carries a pair of laterally spaced rear clamping fingers  76 ,  78  movable between inoperative and operative positions by pneumatic cylinders  80 ,  82  respectively. The rear portion  40  also carries a plunger  84  movable between upper and lower positions by a pneumatic cylinder  86 . 
     The operation of the above described mechanism will now be explained. The manner in which the various moving parts are controlled will be readily apparent to a person skilled in the art on the foregoing and following description. 
     Referring to FIG. 3, the suction cups  66 ,  68  are moved forwardly by extension of the pneumatic cylinders  70 ,  72  and activated to cause them to engage the upper part of the rear of the rearmost bag  12  of the supply thereof mounted on bag receiving rods  14 ,  16 , suction cups  66 ,  68  engaging the rear portion  12   b  of the bag  12  near the upper edge thereof. As shown in FIG. 4, the pneumatic cylinders  70 ,  72  are then contracted to pull the upper edge portion of the back of the bag  12  rearwardly to slightly open the top of the bag, with the upperly extending flap  22  on the front of bag remaining in position on the receiving rods  14 ,  16 . The rear gripping fingers  76 ,  78  are then actuated by extension of pneumatic cylinders  80 ,  82  so that the rear clamping fingers  76 ,  78  extend into the upper end of the bag and clamp the upper edge portion of the back  12   b  of the bag between the rear gripping fingers  76 ,  78  and a stop member  90  (see FIG. 4 a ). The top portion of the bag above a reclosable seal  12   c  is then open. 
     The side gripping fingers  58 ,  62  are then actuated by extension of the pneumatic cylinders  60 ,  64  so that the side clamping fingers  58 ,  62  enter into the bag  12  on opposite sides thereof and clamp the respective side of the bag  12  against a stationary stop  92  (see FIG. 4 b ). 
     Referring now to FIG. 5, the suction cups  66 ,  68  are then de-actuated and the rear portion  40  and middle portions  38 ,  39  of the carriage  24  are moved rearwardly. At the same time, the plunger  84  is moved downwardly into the bag  12  to open the reclosable seal  12   c  and the bag  12  is therefore now completely open. The open bag is then filled by means of a filling mechanism (not shown), the nature of which will again be readily apparent to a person skilled in the art. 
     Referring now to FIG. 6, the rear portion  40  and middle portions  38 ,  39  are then moved forwardly to their original positions (as shown in FIGS.  3  and  4 ). At the same time, pneumatic cylinders  80 ,  82  are actuated to release the rear clamping fingers  76 ,  78  from the front of the bag. Thus, at this stage, the filled bag is nearly closed, with the side clamping fingers  58 ,  62  still in the clamping configuration and with the upwardly extending flap  22  still mounted on the receiving rods  14 ,  16 . A conventional closing mechanism (not shown) moves laterally across the top of the bag, the pneumatic cylinders  60 ,  64  are then de-actuated to release the side clamping fingers  58 ,  62  from the filled bag, and the closing mechanism then closes the bag. The carriage  24  then moves to the left, tearing the bag  12  away from the flap  22  in known manner, and discharges the filled and closed bag onto a conveyor  90  as indicated in FIG.  1 . 
     As will be particularly evident from FIG. 6, (and also FIGS.  3  and  4 ), the middle portions  38 ,  39  of the carriage  24  and also the pneumatic cylinders  60 ,  64  are skewed slightly laterally inwardly and forwardly by a small angle so that, when the carriage  24  is in the forward position, the side clamping fingers  58 ,  62  are in a forward position which is as close as practically possible to the front of the bag so that the upper end of the bag is only open a small amount. 
     In the above described embodiment, the side clamping assembly included clamping fingers which moved into the interior of the bag. For bags with wide side edge seams, as shown in FIGS. 7 and 8, the side clamping assembly may include openable and closeable jaws  102 ,  104  operable by pneumatic cylinders  106 ,  108  respectively to grip the sides of the bag in pincer-like fashion. 
     It should be noted that the bag may not necessarily be provided with a reclosable seal  12   c , but only with closure provided by the previously mentioned closing mechanism. 
     The advantages of the invention and other embodiments thereof will now be readily apparent to a person skilled in the art from the foregoing description of preferred embodiments, the scope of the invention being defined in the appended claims.

Technology Classification (CPC): 1