Abstract:
A bagging machine comprising an article discharge chute for releasing one or more articles in an open bag held thereunder at a bag loading position. A plurality of collapsed plastic bags are supported under and adjacent the discharge chute. The mouth of an outer one of the plastic bags is opened with a bag opening clamp and the rear and front wall of the bag are held spaced apart so as to receive one or more articles therein through the discharge chute. Bag holding and stretching fingers grip the bag at opposed upper side edge portions thereof whereby to transfer the first bag filled with the articles to a sealing station after the front and rear walls of the bag are detached from their bag opening securement. At the sealing station, a clamp engages the stretched rear and front walls together below the mouth opening and the rear and front walls together are sealed across the mouth opening above the clamp after release and removal of the bag holding and stretching fingers to effectuate a substantially crease-free seal entirely across the mouth opening of the bag.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     A bagging machine for filling and transferring a plastic bag from a bag loading position to a bag sealing position and wherein the transfer of the bag is effectuated by clamping fingers which engage the bag in opposed end edges whereby to stretch the bag so that the front and rear wall thereof are clamped together in a stretch condition to effect sealing of the bag entirely across the mouth opening with substantially a crease-free seal entirely across the bag. 
     2. Description of Prior Art 
     It is known to stretch open ends of plastic envelopes at a sealing station to eliminate creasing in a plastic film wrapping during the sealing cycle. For example, U.S. Pat. No. 4,024,692 discloses such an envelope sealing machine. U.S. Pat. No. 3,896,605 also teaches a bag handling machine wherein fingers enter into the bag to stretch the mouth opening. However, these fingers are not utilized to effectuate the transfer of the bag, after the bag is filled, and to stretch the mouth opening while supporting the bag to transfer it to a sealing station where a substantially crease-free seal is effectuated. Also, with the prior art, it is usually necessary to remove the bag stretching means to effectuate an evacuation of the bag when it is necessary to evacuate air therefrom prior or after sealing of the bag. 
     SUMMARY OF INVENTION 
     It is a feature of the present invention to provide a novel bagging machine wherein bag holding and stretching fingers are secured at opposed upper side edge portions of the open mouth of the bag at the filling station whereby to clamp and transfer the bag with articles therein to a bag sealing station so that a substantially crease-free seal can be made with the bag holding and stretch means removed therefrom. 
     Another feature of the present invention is to provide a bagging machine wherein the bag holding and stretch means is utilized to evacuate air from inside the bag just prior to the sealing of same. 
     Another feature of the present invention is to provide a bagging machine having bag holding and stretch means which are adjustable to suit bags of different sizes and which can be used to evacuate air from the bag immediately before sealing. 
     Another feature of the present invention is to provide a bagging machine having bag holding and stretch means which cooperate with a sealing station whereby to effectuate a substantially crease-free seal entirely across the mouth opening of the bag and without subjecting the hot seal to stretching by the load in the bag during the sealing thereof. 
     According to the above features, from a broad aspect, the present invention provides a bagging machine comprising an article discharge means for releasing one or more articles in an open bag held thereunder at a bag loading position. Means is provided for supporting a plurality of collapsed plastic bags under and adjacent the discharge means. Means is further provided for opening a mouth of an outer one of the collapsed plastic bags. The means for opening has positive bag holding means for holding a portion of the rear and front wall of the outer bag in spaced relationship to open the mouth to receive the one or more articles therein from the discharge means. Bag holding and stretch means is securable to opposed upper side edge portions of the open mouth bag for clamping and transferring the first bag, when filled with the articles, to a sealing station after the positive bag holding means are released. The bag holding and stretch means also stretch the open mouth of the bag to pull the rear and front wall taut to prevent creasing during sealing of the bag. Clamping means is provided to clamp the rear and front wall together while the bag is in a stretched condition. The clamping means is spaced below the mouth opening. Sealing means is provided to seal the front and rear wall together across the mouth opening above the clamping means after release and removal of the bag holding and stretch means to effectuate a substantially crease-free seal entirely across the mouth opening of the bag. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 is a simplified side view illustrating some of the elements of the bagging machine of the present invention; 
     FIG. 2 is an end view of FIG. 1 showing the bag positioned at a loading station and at a sealing station; 
     FIG. 3 is a side view illustrating the adjustable support mechanism for the bag holding and stretching clamping finger elements; 
     FIG. 4 is a side view illustrating the construction of the bagging machine of the present invention and the alignment between the bag loading position and the sealing station; 
     FIG. 5 is an enlarged side view of the clamping finger elements and their actuation mechanism; 
     FIG. 6 is a side view illustrating the construction details of the adjustable support mechanism for the clamping finger elements; 
     FIG. 7 is a side view illustrating the detailed construction of the sealer mechanism; 
     FIG. 8A is an end view showing the relationship of the clamp with respect to the clamping finger elements at the bag sealing station; 
     FIG. 8B is similar to FIG. 8A but showing the clamping finger elements removed from the bag at the sealing station with the position of the sealing bag and the bag severing wire; and 
     FIG. 9 is a section view through the bag opening clamp showing its cooperation with a microswitch. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, and more particularly to FIGS. 1 and 2, there is shown generally at 10, the bagging machine of the present invention and which is herein mounted on a rectangular frame 11. In an upper part of the frame, there is secured a discharge chute 12 which is fed one or more articles 13 therein for loading into a bag 14 held under the chute 12 in an open bag loading position. A plurality of collapsed plastic bags 14&#39; are held under the chute with their tabs 15 disposed against the wall 12&#39; of the chute and held thereagainst by inclined wicker pins 16. A load plate 17 is positioned on the wicker pins 16 against the plurality of collapsed bags 14&#39; to keep them compressed and for movement of the collapsed bags along the pins to their loading position. An air jet 18 is disposed in the vicinity of the bottom open end 19 of the chute 12 and the slit opening of the mouth of the first bag 14&#34; to open the mouth of a first bag 14&#34;, as shown in FIG. 4. The air jet blows open the front wall 20 of the bag from its rear wall 21 and a clamp 22 is displaced in the mouth opening and pulls the front wall of the bag to clamp it against a clamping surface or plate (see FIG. 9). Once the bag is open, the articles 13 are discharged therein. The bag is held by the clamp 22 and the holes in the flap 15 held by the wicker pins 16. It is also known to provide a clamping piston head against these flaps 15 to clamp the flaps between such piston head and the wall 12&#39; of the chute. Such piston head is not shown herein but well known in the art. So far, this form of bag opening holding, and loading means is well known. 
     The present invention is concerned with a further bag holding and stretch means generally shown at 23 in FIG. 1 but better illustrated with additional reference to FIGS. 3 to 6. As illustrated in FIG. 3, there are two bag holding and stretch means or mechanism 25 each supported on an adjustable support means 26, with both support means being secured to a displaceable support frame 27 whereby to displace the bag holding and stretch means 25 from the bag loading position 28 to the bag sealing position 29, as shown in FIG. 2. 
     Describing firstly the bag holding and stretch means 25, it is comprised by a pair of clamping finger elements 30 with one of the finger elements, namely element 31, being positioned inside the open mouth of the open bag 14 while the other finger element 32 is pivotal and positioned on the outside and clamped against the upper side edge portion of the bag. This upper side edge portion is usually the side portion where the bag has a fold crease or may have a seam. As shown in FIG. 5, the inner finger 31 is immovably connected to a pivoting lever 33 and extends downwardly at right angles thereto. The outer finger element 32 is pivotally secured to the pivot lever 33 on pivot connection 34 and is connected to an actuating arm 35 which is connected to a piston rod end member 36 so that extension and retraction of the piston rod 37 by the piston cylinder 38 causes the outer finger to pivot and move into clamping or unclamping relationship with the inner finger 31. 
     As shown in FIG. 5, the inner finger element 31 may be a hollow finger defining a conduit 39 therein with the upper end of the inner finger element 31 being connected to a flexible conduit 40 which is connected to a suction pump (not shown) whereby to evacuate air from the bag prior to sealing, as will be described later. 
     As shown in FIG. 3, the clamping fingers are in an open condition with the outer finger element being in its position 32&#39; as illustrated in FIG. 5. In order to position the inner clamping finger element 31 inside the bag, the pivoting lever 33 is secured to an axially rotatable connecting rod 41 which is rotatable in the directions as illustrated by arrow 42 to move the clamping finger elements 30 inside and out of the bag. One end of the rod 41 is welded to the pivot lever 33 and its other end, as shown in FIG. 6, is welded to a pivoting lever 43 which is displaced to rotate the rod 41 along the vector 44. This displacement is achieved by a finger actuating piston 44 having its cylinder pivotally connected at one end 45 to a frame member 46 while its piston rod end 47 is pivotally connected at 48 to the pivoting lever 43. Thus, when the piston rod 49 is extended, the clamping finger elements 30 will move in or out of the bag and when retracted, it will effectuate the other corresponding movement. 
     As shown in FIG. 3, the displaceable or movable support frame 27 is slidably connected at opposed ends by side frame members 50 to opposed slide rods 51 and displaced thereon by an actuating piston 52 whereby to transfer the loaded bag from its loading position 28 to the bag sealing station 29, as shown in FIG. 4. 
     Referring again to FIG. 6, the displaceable support frame also supports a pair of bag stretching pistons 53, 54 which have their piston cylinder adjustably connected at a rear end by a displaceable connector 55 secured to an adjustable rod 56. The adjustable rod is a threaded rod and the adjustable element 55 is simply a washer-like element secured to the cylinder end and secured at a desirable position along the threaded rod by means of threaded nuts 57 disposed on both sides of the washer-like element 55. This adjustable rod 56 permits lateral adjustment of a movable frame 58 which supports the rotatable connecting rod 41. The rod 56 is supported by a displaceable bracket 60&#39; attached to a guide rod 60 at a desired fixed position. The movable frame 58 has guide bushings 59 which are displaced on the guide rod 60. Therefore, depending on the width of the bag being handled by the bagging machine, the position of the rotatable connecting rod 41 and hence the position of the clamping finger elements, can be adjusted so as to have the finger elements enter the bag at a precise location to engage the upper side edge portion of the bag open mouth. 
     As previously described, once the clamping finger elements have entered the bag and clamped it, and the bag is loaded, it is now ready to be transferred by the clamping finger elements and during the transfer or when the bag reaches the sealing station, the bag is stretched by the clamping finger elements. This stretching is achieved by the piston rod end 61 of the bag stretching piston 54. This piston rod end 61 is connected to the movable frame 58 and extends into a stroke adjusting member 62. The piston rod has a connector 67 to connect the piston rod end 61 to the movable frame 58. Adjusting member 62 is a sleeve member having an abutment end wall 63 which is secured at a predetermined distance from the piston rod end 61 whereby to limit the length of the stroke and, therefore, limiting the amount of stretching to be effectuated by each of the clamping finger elements. An adjustment means such as a fastening bolt 64 and slot 65 provided in a sleeve side wall 66 constitutes the adjustment means. Accordingly, if the side wall is displaced so that the abutment wall 63 is positioned as shown in phantom lines at 63&#39;, then the stroke or the amount of stretching effectuated by each clamping finger element will be that distance as shown at S. 
     The finger pivot lever 33 is provided with an adjustable connecting member, herein a sleeve member 68 as shown in FIG. 6, having a set screw 69 whereby to adjust the lateral position of the clamping finger elements along the rotatable connecting rod 41. This permits adjustment for the lateral position of the clamping finger elements 30 with respect to the width of the open bag at the loading position to align them with the creased side edges of the bag or the seam edges. Thus, when handling bags of different sizes, it is necessary to adjust this position. Accordingly, the clamping finger elements are adjusted in accordance with the length of the open mouth of the bag, the width of the bag, and the amount of stretching desired is also adjustable. 
     Referring now to FIGS. 4 and 9, and as previously described, the front wall 20 of the outermost ones of the collapsed bags 14&#39; are clamped by clamp member 22. This clamp member is better illustrated in FIG. 9 and as herein shown, it comprises a stationary clamp plate 70 against which a movable clamp plate 71 is positioned to open a first bag and clamp an upper edge portion 20&#39; of the front wall 20 of the bag in an open position. A microswitch 72 is secured behind the clamp plate 70 and has a spring loaded contact member 73 which extends through a hole 74 in the clamp plate 70 and extends forwardly thereof. This spring loaded contact member is also aligned with a hole 75 provided in the movable clamp plate 71 so that, when a bag is clamped, the upper edge portion 20&#39; of the bag will obstruct the hole 75 and cause the contact member 73 to move inwardly in the direction of arrow 76 to effectuate a switch closing. This switch closing provides a signal indicative of the presence of an open bag and which initiates an operating cycle of the bagging machine. The articles may then be unloaded into the bag and the clamping finger elements move into clamping engagement with the opposed side edges of the bag. Once the clamping finger elements are engaged, and after a predetermined time delay, the clamping finger elements are displaced by the displaceable support frame 27 to the bag sealing station 29. During this transfer, the bag stretching piston 53, 54 have been actuated to displace the movable frame 58 and the rotatable cam rod 41 to effecutate stretching of the open mouth of the bag. A control circuit, not shown, but obvious to a person skilled in the art, controls the sequence of operation of the machine. 
     Referring now to FIGS. 7, 8A and 8B, there is shown the sealing station where the bag is sealed and released on a discharge conveyor 80 as shown in FIG. 4. The filled bag is brought into an opening of a support frame 81 along the axis 82 which is intermediate a clamp plate 83 and a clamping bar 84. The clamp plate 83 is secured to a clamp plate actuating cylinder 85 which firstly displaces the clamp plate to its position as shown by phantom lines 83&#39;. Thereafter, the clamping bar 84 is displaced in the direction of the clamp plate whereby to clamp the stretched rear wall 21 of the bag against the stretched front wall 20. The clamping bar 84 is secured to a frame 84&#39; and is adjustable thereon whereby to vary the width of the clamping bar, dependent on the size of the bags used, so that the opposed ends 86 of the bar are closely aligned with the inner finger member 31 which is still positioned inside the bag and which maintains the front and rear walls stretched to prevent creasing. After the clamping bar has clamped the filled bag against the clamp plate 83, the displaceable support frame 27 is then moved upwardly in the direction of arrow 87, as shown in FIG. 8B, by actuating the piston 52 whereby to move the clamping fingers to the loading position to engage a further bag while the filled bag is being sealed. 
     As shown in FIG. 8A, should the bag be evacuated of air by the vacuum applied to the inner finger 31, there is very little bag opening left to permit air to be admitted into the bag after the removal of the inner finger element 31. Also, the walls of the bag are collapsed against its contents. Accordingly, immediately after the inner finger element 31 moves out of the opposed narrow end portions of the bag, the heat sealing bar 88 immediately moves in against the clamp plate to seal the entire width of the bag, as shown in FIG. 8B. Because the front and rear walls were in a stretched condition and clamped in this condition, there is no crease formed in this portion. Also, because the unclamped opposed end portions are very small, it is unlikely that these will crease. In fact, they are flattened by the sealing bar 88 and do not form any creases. 
     The heat sealing bar 88 has a resistive heating ribbon 89 disposed on the forward face thereof and covered by a TEFLON sheet 90 which is displaceable thereover. The TEFLON sheet is wound about and between a supply reel 91 and a take-up reel 92 and the take-up reel is manually or automatically rotated from time to time to assure that a clean TEFLON section is disposed intermediate the plastic bag and the hot ribbon. This TEFLON sheet prevents molten plastic to adhere to the heating ribbon 89. A hot severing wire 93 is supported above the hot ribbon whereby to sever the excess top portion of the bag above the seal at the same time as the seal is being made. The hot wire 93 is disposed forwardly of the TEFLON sheet 90. After the bag has been sealed, the sealing bar 88 is retracted by the piston 94 with the clamping bar still in engagement so that the weight of the bag is supported between the clamping bar and the clamp plate to permit the seal to cool down and not subject the seal to the weight of the products in the bag. This also assists in obtaining a substantially crease-free seal. 
     It is within the ambit of the present invention to cover any obvious modifications thereof provided such modifications fall within the scope of the appended claims.