Patent Publication Number: US-6990787-B2

Title: Method and apparatus for packing of items

Description:
This application claims the benefit of Danish Application No. PA 2001 01481 filed Oct. 8, 2002 and PCT/DK02/00671 filed Oct. 7, 2002. 
   BACKGROUND OF THE INVENTION 
   Method for packing items or loose material in suspended film bags. 
   The present invention relates to a method and an apparatus for packing items in film bags which are conveyed through a filling station in a continuous web where a filling of the individual bag items is performed, which bags are then closed and separated from the continuous web for establishment of individual packings. 
   A basic example of this technology is mentioned in EP-696997 in which it is stated that the opposite upper edge areas of the bag item web is made with bent rim parts formed by grooves for drawing in on conveyance bars which have a mutual expansion for producing an opening of the bag items in the direction of conveyance, such that these can be filled, for example through a superjacent funnel, where after the conveyance bars are narrowed against each other again for temporary closing of the filled bag items. These can then be closed completely by welding below said groove parts where after these are cut off and the items mutually separated. As an alternative it is stated that instead of groove parts, edge thickenings may be applied which may be received in slotted conveyance pipes for a quite corresponding conveyance of the bag items. 
   Since then other types of means have been suggested for catching and carrying the opposite upper edges of the bag item web, for example as stated in EP 0 555 321 B where special catching chains are used for the purpose without special requirements to the design of the upper edge areas of the folded bag item web. This is of substantial significance in that as an end product a simple rolled op flat film web without local thicknesses may be used, however in return there are considerable problems with regard to both the guidance of the opposite edges of the bag items for a safe engagement with the chains and with regard to a desirably inexpensive embodiment of these chains. 
   In EP 0 396 838 and EP 0 825 116 it is furthermore stated that a flat pipe web of the film can be applied which can continuously be cut open along its upper edge with integrated unfolding and catching of the thus cut open upper edges without these being specifically designed neither as grooves nor with thickenings which will indicate a distinct simplification of the requirements for the production of the bag web. The cut open upper edge parts are unfolded to be squeezed between respective moving belts made with longitudinal recesses and corresponding pressing cords whereby a suitably firm carrier engagement can be established. 
   However, this engagement is not firmer than axial slidings may occur between the upper edges of the bag web and the associated means for belt transport whereby uncertainty may arise as to whether a conveyed item has been conveyed completely synchronously with the conveyor belts. Moreover, deviations may arise with regard to height location of the area of the web sides that is squeezed between the conveyor belts which may be of importance as to whether the filled bags are completely closed at the location intended for this exact purpose, for example in relation to print on the bag. 
   In DK PA 1998 00548 is described a construction which uses a simplified flat bag web as said opening edge is merely closed when the web is introduced on a single carrier bar and is continuously cut open in a station where the thereby upright rim strip parts are unfolded in order to be laid down on opposite chains. In advance, these strip parts are made with a row of holes which are led down into upwards directed holding studs on the carrier chains during folding down whereby a safe carrier and propelling engagement is achieved without any special profiling of the opening edges. 
   SUMMARY OF THE INVENTION 
   During use of the last described construction it has turned out that it is true that it comprises the advantages described, however they can be obtained in a simpler way. It is the object of the invention to provide a method for packing items or loose material in film bags which in a continuous web are conveyed through a filling station which is simplified in relation to prior art constructions and which allows for a higher speed through a plant performing the method. 
   It is achieved with a method which is peculiar in that during conveyance on a smooth guide rail, the bag web is introduced between a left and a right chain which at a distance identical with the distance between the holes in the bag web carries horizontal studs which from each side are introduced into the holes designed in the bag web whereby longitudinal groove surrounding the end of the horizontal studs secure the studs&#39; retention of the bag web. 
   An apparatus for performing the method is peculiar in that the guide rail changes into a broader mandrel-shaped rail part designed with first longitudinal grooves at each side, which rail part changes into a wedge-shaped body with second longitudinal grooves in continuation of the first longitudinal grooves which wedge-shaped body changes into two parallel third longitudinal grooves whereby two endless chains with horizontal studs having a distance corresponding to the distance between the holes in the bag web are maintained against the longitudinal grooves by rails and guide rolls such that the studs end up everywhere inside the longitudinal grooves as the two chains move in parallel with the studs opposite each other and as the distance between the third longitudinal grooves corresponds to the distance needed for obtaining a desired opening of the bags. 
   DESCRIPTION OF THE DRAWING 
   In the following, the invention will be described in more detail with reference to the drawing where 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows the essential components in an apparatus performing the method, 
       FIGS. 2   a–d  show a number of cross-sections of the introduction of the bag web, and 
       FIG. 3  shows links in the chain with fittings and studs. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   From a not shown depot, a bag web  1  of synthetic material is conveyed in the direction of the arrow on a smooth rail  2  (cross-section  2   a ) which has a rounded part  3  facing the direction of the conveyance of bags. The bag web hangs in the upper part of the plastic film which is designed for this purpose, and it is provided with customary incisions and weakened spots which are not shown. Moreover, the upper part is provided with a number of perforations for indications of holes having a fixed mutual distance. The rail changes into a thicker mandrel  4  (cross-section  2   b ) with a groove  5 ,  6  designed at each side. The grooves have a width and a depth corresponding to studs  7  which by means of fittings  8  with a fixed distance are arranged on two endless chains  9 ,  10 . The studs move synchronously with the bag web  1  in such a way that the studs from each side penetrate a layer  11 ,  12  in left and right side, respectively, of the upper part of the bag web. The plastic film is distended by the mandrel  4  and the studs, and it passes a vertical knife  13  at the upper side of the mandrel, after which the two now separate parts  11  and  12  of the bag web are eventually carried by the chains provided with studs. Due to the grooves  5 ,  6  designed surrounding the end of the studs  7 , the plastic film cannot slide beyond the ends of the studs. 
   The mandrel changes into a wedge-shaped block  14  (cross-section  2   c ) which is correspondingly provided with longitudinal grooves  5 ′,  6 ′, and during the further transport of the bag web  11 ,  12 , the bags are gradually opened. When achieving maximum opening, the block  14  changes into longitudinal rails  15 ,  16  (cross-section  2   b ) still with longitudinal grooves  5 ″,  6 ″, and these rails convey the bag web forward below and between regular stations for filling, sealing, cutting free etc. All the time, the chains  9 ,  10  with the studs  7  take care of the transport, and the guiding of the chain by means of various rolls R, and rails take care of the studs remaining in the grooves  5 ,  5 ′,  5 ″,  6 ,  6 ′,  6 ″ such that the plastic film cannot slide off. In a suitable place, a driving gear wheel is placed for each chain. At the end of the packing plant (not shown) the studs are pulled apart as the chains run about a guide roll, and the bags cut free can be gripped at this place and transported away or fall onto a conveyor belt. It is noted that where  FIG. 1  in merely schematic such that certain dimensions are exaggerated due to clarity, then  FIG. 2  at least with regard to the proportions between the incoming elements corresponds to a practical construction. 
   One of the chains ( 10 ) is shown in.  FIG. 3  where every other link L is provided with fittings  8  carrying a projecting stud in the plan of the chain. 
   This improved effect compared with prior art is among others ascribed to the fact that according to the present invention, the studs  7  are shorter, and that gravity is not necessary in order to ensure that the plastic film  11 ,  12  remains on the studs during transport.