The present invention concerns a method and a ma- chine for the bunching of bags, especially bags for the packaging of bread by industrial bakers.

Within the baking industry, paper bags are use to an increasing extent for the packaging of products (bread).

The bags consist substantially of paper, but with a transpa- rent side portion so that the contents of the bag can be seen by the purchaser when the bread packaged in this manner is lying on the shelves at the retailers or in the supermarkets.

The bags give an impression of bakery tradition and environ- mental correctness, in that the individual loaves are wrapped in packaging which consists mainly of paper, and the packa- ging also provides the possibility of sale by self-service.

The loaves are packaged mechanically by being con- veyed in line to the packaging station, which comprises a bag elevator on which a stack of folded bread bags is placed and secured by a U-shaped rack, the legs of which are introduced through holes punched in a flap extending from the underside of the bag. When being filled, the mouth of the bag is held open by a vacuum lifter, so that the bread can be pushed in- side the bag, after which the bag containing the bread is pu- shed/drawn back and fed further in the pre-packaging process.

When drawn back, the bag is torn out of its fastening in the U-shaped rack on the bag elevator by simultaneous tearing- over of the holes punched in the flap extending from the un- derside of the bag. The bag elevator is raised a distance corresponding to the thickness of the bag, and the vacuum lifter opens the mouth of the next bag which is thus ready to be filled.

The insertion of the bags in the bag elevator is effected by stacking the bags in such a manner that the holes

punched in the bag flaps lie over each other, after which the stack is secured by insertion of the U-formed holding profile which is secured to the elevator's support surface. As a con- sequence of the demand for precision in the stacking, this work can be time consuming.

The solution to this problem has resulted in the bags after the bunching being provided with a binding which is introduced through the holes in the flap of the bag, so that the holes in the stacked bags are held substantially op- posite each other.

To serve this purpose, various solutions have been proposed for maintaining the holes opposite each other, such as U-shaped metal hangers bent at different angles. However, the presence of these has led to certain inconveniences in the subsequent packaging and palletizing operations, in that the use of said hangers can easily give rise to a tearing of the upper sides of the bags. Moreover, the presence of the hangers will result in an undesired increase in the volume of the bag stacks. As alternative solutions, there have similar- ly been considerations with regard to the implementation of the binding in the holes with clips, but this solution is not desired by the users, in that if they are not removed, these clips are introduced into the bag together with the bread.

The preferred solution to the problem of binding is provisionally that the binding is effected by the introducti- on of bag closers (the so-called gun clips consisting of a piece of soft steel wire laid between two plastic bands wel- ded together) through the holes punched in the stacked bags, the ends of the bag closers being joined by being twisted to- gether one or two times. The advantage herewith is that the laying-in of the bags is made considerably easier in that the holes are immediately opposite each other, whereby the bags can quickly be secured by introduction of the U-shaped profi-

le through the punched holes, after which the bag closers can easily be removed.

The packaging and binding through the holes of said bags desired/demanded by the users for the quick insertion in a bread packaging machine has, however, given rise to certain problems for the bag producers, in that the insertion of said gun-clips through the holes in a stack of bags, and the sub- sequent twisting together of the ends of said clips, is a process which has proved to be time consuming to carry out manually, and almost impossible to carry out mechanically.

However, the bag producers carry out the insertion of the gun-clips and the manual twisting together in the final bag- packaging process, where the bags are bunched in a known man- ner by being lashed before they are palletized. The manual effort connected with the binding through the holes has led to an undesired increase in the costs of production.

A possible solution to the packaging problem could be to effect a mechanical sewing-together of the bags in the flaps at the bag opening, similar to the sewing-together with a single thread which is fed through two different points in said flaps which exist in stacks/bundles of quite traditional paper bags which are used in e. g. baker's shops etc. For va- rious reasons, this solution has not been found to be expedi- ent by the users, in that as a consequence of the thinness of the thread, the sewing-together does not provide the necessa- ry stability in the bag stack, which means that the bags can mutually be displaced in the sideways direction so that the holes are not placed opposite each other.

In the production of said bread bags, the last ope- ration in the production process comprises the punching of said holes in the flaps in a stack of bags, which during the punching are secured by means of clamping elements.

However, with the invention it has been realised that an expedient bunching of bread bags of the kind discus-

sed can be carried out by taking advantage of the fact that the bag stack, immediately after the punching of the holes in the flaps, is thus secured in a position in which the holes are lying opposite each other, so that a binding through the holes punched in the bag flaps can be implemented by mechani- cal means.

Furthermore, it is preferred that the binding through the holes according to the method takes place before a subsequent bundling together, packaging and possibly palle- tizing of the bag bunches.

A particularly preferred method for the bunching of bags of the kind discussed is disclosed and characterized in claim 2, this being divided into two alternative methods, all depending on which type of band-shaped connecting means are used in the mechanical bunching of the bags.

The method disclosed in 2a) is thus one whereby a weldable plastic band is used for the bunching, and wherein use is made of a welding tongue for the heating of the oppo- sing sides of the weldable plastic band to the preferred wel- ding temperature, which is determined by the material of which the plastic band consists. After the heating of the plastic band, the heated surfaces of the plastic band are pressed together, and the plastic band is cut through by me- ans of a cutting element on that side of the weld which is closest to the feeding element for the plastic band. More- over, it should be mentioned that use can well be made of a weldable plastic material which is reinforced, e. g. with me- tal wire.

With the alternative method 2b), where use is made of gun-clips for the bunching of the bags, a cutting element is used for the cutting through of the gun-clip closest to the feeding element for the gun-clip, and where the joining- together of the ends is instead carried out by twisting to- gether by mechanical means.

A machine for the execution of the method according to claim 1 or 2, for the bunching of bags of the kind discus- sed in the introduction, is disclosed and characterized in claim 3, i. e. a machine which comprises mechanical feeding means which at the same time secure a bunch of bags with ho- les punched in the bag flaps so that the holes lie opposite each other, and such that by means of a mechanical guiding element, which either in itself is led through said holes, or by mechanical feeding through the guide element to a position above the bag stack, it is possible to feed through the end of a rolled supply of connecting means to a position in which the end is gripped and secured by a clamping element during a relative displacement by mechanical means between the feeding means for the bag bunch and the guide element and the clam- ping element, so that the foremost end of the bag stack (the end with the flaps with the punched holes) is free of two pressure elements for the pressing together of the opposing sides of the connecting means. Like claim 2, depending on the type of connecting means used for the bunching of the bags, claim 3 is similarly divided respectively into a configurati- on which takes into account that the band-shaped connecting means consists of a weldable plastic material (3a), and a configuration which takes into account that the band-shaped connecting means consists of gun-clips (3b).

With the view of increasing the bunching speed and herewith the efficiency of the machine, the machine according to the invention can with advantage further comprise hollow guide elements for weldable plastic bands, corresponding to the number of holes punched in the bag flaps in a bunch of bags, pressure and cutting elements and welding tongues, al- ternatively rotatable gripping jaws. The advantage herewith lies in the fact that the binding through the holes in the bag flaps in a bunch of bags can be carried out mechanically in one operation instead of a number of operations correspon-

ding to the number of holes. A further advantage achieved he- reby is fewer operations per bag bunch and thus less wear on the moving parts of the machine.

Depending on the stiffness and smoothness of the rolled-up connecting means, the mechanical guide means for the rolled-up connecting means can with advantage comprise both feeding and securing elements for the feeding and secu- ring of the rolled-up band-shaped connecting means which is led through the hollow guide elements.

With the invention, it has also been realised that the machine according to the invention can also be used for the bunching of bags with weldable plastic bands which are reinforced, e. g. with metal wire, such as gun-clips, which in practice means that plastic-coated gun-clips can be used to- gether with a configuration of the machine whereby the joi- ning together of the connecting means is effected by welding.

For handling reasons, the machine for effecting the mechanical binding through the holes can with advantage be built together with the production line for the bags in imme- diate continuation of the punching process.

Moreover, the machine can with advantage be built together with packaging machines for subsequent packing and palletizing of the stacks of bags bunched in the machine.

The invention will now be described in more detail with reference to the drawing, where fig. 1 is a perspective view of a bag used by indu- strial bakers, fig. 2a-2h is a schematic plan view of the punching of holes and the binding of same in a stack of bread bags, fig. 3a-3f is a schematic side view of the method according to the invention for binding through the holes in a stack of bread bags, and fig. 4 shows an end view of a machine for the me- chanical bunching of bags according to the invention, where

the feeding means for the feeding of the stack of bags con- sists of a conveyor.

Fig. 1 shows an example of the type of industrial bakers'bread bag 2 which are bunched in stacks by the method and the machine according to the invention. The bags 2 con- sist of a tunnel-shaped element 50, the upwardly-facing side of which comprises a transparent portion 51 which extends in the bag's lengthwise direction, where the bottom 52 of the bag is formed by the bending 54 of the one end of the element 50 and fastening between the bend and the underside 56 of the element 50. In extension of the underside 56 at the mouth of the bag 6, there is an extending flap 8 in which holes 18,20 are punched for the purpose of bunching of a stack of bags.

Fig. 2a shows how a stack 2 of bread bags (in the following called bread-bag stack 2 or bag-stack 2) is intro- duced for the punching of the holes 18,20 in the flap 8 ex- tending at the bag openings 6, so that the bags lie precisely over each other in the stack 2, in that the bags are aligned by pushing means 19,12 against a stop-face 14. Hereafter, the bag-stack 2 is clamped between two holding elements 16 and fed by a sideways displacement for the punching of a first hole 18 in the bag flaps 8, fig. 2b-2c, and further for the punching of a second hole 20 fig. 2d.

The bag-stack 2 with the punched holes 18,20 is then led further in the sideways direction where a second set of holding elements 22 take over the feeding of the stack 2 for binding in the holes 18,20, which cf. fig. 3a-3b is ef- fected by the insertion of a hollow guide element 24 down through the holes 18,20 for the introduction of the leading end of a band 26, in this case a weldable plastic material, said band 26 being rolled-up in a not-shown supply. The lea- ding end of the band 26 protrudes in front of the front end of the guide element 24, and is gripped by a set of lateral- ly-displaceable clamping elements 28 lying on the opposite

side of the guide element's insertion side in the holes 18, 20 in the bag-stack 2, in the shown example embodiment on the underside of the bag-stack.

The guide element 24 is then drawn back to the start position over the bag-stack 2, and this is followed by a displacement of the bag-stack 2 in its lengthwise direction by a lateral displacement of the holding elements 22, whereby the band 26 is drawn out through the guide element 24 so that the ends of the bag-stack are lying opposite the operation area for two pressure elements 30,30', cf. fig. 3c, which press the opposing sides of the band 26 in against a welding tongue 32, cf. fig. 3d, where the band material is heated to a desired welding temperature. At the desired welding tempe- rature, the welding tongue 32 is moved away from the pressure elements'operation area, after which the welding together of the opposing surfaces of the band 26 is effected by the pres- sing-together of the heated surfaces by the pressure elements 30,30', cf. fig. 3e. During the pressing-together of the heated surfaces, there is also effected a cutting-over of the band 26 at the side of the weld 34 facing towards the guide element, this being carried out by a laterally-displaceable knife 36 which is pressed in against a cutting surface on the uppermost pressure element 30'. Hereafter, the clamping ele- ments 28 are moved to the start position, and the process can be repeated with a new bag-stack 2. The bag-stack 2 is now fed further for lashing, packing and palletizing.

A second preferred example embodiment of the machi- ne according to the invention is shown in fig. 4. Here, the mechanical feeding means for the feeding and holding of the bag-stack 2, so that the punched holes 18,20 in the flaps 8 lie precisely over each other, consist of a double conveyor 23 with a support part 23'and an overlying pressure part 23'', between which parts the bag-stack 2 is clamped. The free end of the plastic band 26 is fed mechanically through

the hollow guide element 24 and is led down through the holes 18,20 in the bag-stack 2, after which a clamping element 28 grips and holds the end. The clamping element 28 and the hol- low guide element 24 are then moved over the bag-stack 2, so that the foremost end of the bag-stack is freed from the pressure elements (not shown) which press the opposing sides of the band 26 against a welding tongue 32, where the band material is heated to a desired welding temperature. At the desired welding temperature, the welding tongue is moved away from the pressure elements'operation area, after which the welding-together of the opposing side surfaces of the band 26 is effected by the pressing-together of the heated surfaces by the pressure elements 30, cf. fig. 3e. During the pres- sing-together of the heated surfaces, there is also effected a cutting-over of the band 26 at the side of the weld 34 fa- cing towards the guide element, this being carried out by a laterally-displaceable knife 36 which is pressed in against a cutting surface on the uppermost pressure element 30'. Here- after, the clamping elements 28 are moved to the start posi- tion, and the process can be repeated with a new bag-stack 2.

The bag-stack 2 is now fed further for lashing, packing and palletizing. The machine according to this preferred embodi- ment has the advantage that the bag-stack is fed forward and held by a unit, i. e. the conveyor 23,23', 23'', which provi- des the possibility of faster transport to and from the bunching procedure. Moreover, the fact that the feeding ele- ment 24 for the plastic band 26 does not need to be moved through the holes 18,20 in the flaps 8 of the bags for the introduction of the binding band 26, results in the saving of process time, which is important for the machine's capacity.

The machine described in the above can also be used where gun-clips are used as connecting means. The only diffe- rence is merely that instead of welding together the ends of the pushed-through connecting means 26, a twisting-together

of the ends of the gun-clips is effected by means of rotating gripping jaws or other mechanical means, such as rotating rubber disks which are pressed against the clamping elements 30,30', whereby the ends of the gun-clips are twisted around each other.

There is hereby disclosed a method and a machine for producing a bunched stack of bags for use by industrial bakers in the mechanical packaging of bread, which by a me- chanically implemented punching of holes 18,20 in the bag flaps 8, and a subsequent mechanically-implemented binding through the punched holes 18,20, is suitable for quick in- sertion in bag elevators in a packaging machine for industri- ally-produced bread.