Bagmaking Machines For Making Plastics Side-fold Bags With Carrier Handles

Abstract

In a bagmaking machine for making plastic side-fold bags from a stepwise advanced tubular web provided with side folds, the tubular web is cut into lengths, and the bottom seams of the bags are formed by a transverse cutting and welding apparatus. A carrier handle fixing apparatus is controlled such that carrier handles are fed to the leading ends of the cut lengths of tubular web in the opposite direction to the direction of movement thereof and in the plane of movement thereof. The carrier handles are fixed while the cut lengths of tubular web are at a standstill. The finished bags are conveyed by a conveyor. The plane of the conveyor is displaced relative to the plane of conveyance of the cut lengths of tubular web such that discharge of the finished bags is not hindered by the carrier handle-fixing apparatus.

Description

This invention relates to bagmaking machines for making plastics side-fold bags with carrier handles.

Plastics carrier bags with carrier handles which are stiff so as to retain their form and which are welded into the mouth of the bag, have been known for many years (see for example German Gebrauchsmuster No. 1,862,149, U.S. Pat. No. 3,140,038, and French Pat. No. 1,410,939). In the fully mechanized manufacture of plastic bags with carrier handles of this kind, a single-ply web of plastics material was previously folded about its longitudinal center line or a seamlessly extruded tube of plastics material was made into a semitubular form by severing along a fold edge. The superposed edges of the web of material were then spread apart and while the web was stationary, a pair of carrier handles issuing from a carrier handle magazine was inserted by means of a slider between the spread edges and a carrier handle welded to each edge. Then, transverse welds were made and separate bags already provided with carrier handles were separated from the semitubular web of material by transverse severing cuts or by making the transverse welds in the form of severing welds.

This very successful method however only results in the manufacture of side-seam bags which can possibly be provided with a bottom fold. Side fold bags cannot be made in this way, as the operation of attaching the carrier handles to the edges of the mouth of the bag can only be effected while the semitubular web is still in one piece. For this reason it was impossible hitherto to use the fully mechanized method of producing side-fold bags with the above-mentioned carrier handles, although the advantages of side-fold bags over conventional side-seam bags are generally recognized, particularly as regards the filling capacity and the development of the desired rectangular shape of the filled bag.

Modern bagmaking machines for making plastics side-fold bags from a stepwise advanced tubular web provided with side folds produce the side-fold bags by making transverse severing cuts at a distance corresponding to the desired bag length from the leading end of the tubular web, and by making transverse welds for the bottom seams. The finished bags leave the bagmaking machine in a longitudinal position at equal distances apart. On the discharge conveyor means they form a continuous row in which the mouths of the bags extend transversely to the direction of movement and open into the narrow space between adjacent bags, where they are inaccessible for the fitting of carrier handles.

In order to fit carrier handles to the mouths of side-fold bags therefore, the only possible way previously found was either to stack the bags produced and to deliver the stacks of bags to a carrier handle fitting apparatus in a position such that the bags pass through said apparatus in a transverse position in which the mouths of the bags are accessible from the side, or to arrange downstream of the bagmaking machine a turning device for the bags, which turns the bags individually through 90.degree. from their longitudinal position into a transverse position.

However stacking of the bags makes manual work necessary and also requires a great deal of care in handling the stacks of bags, in view of the high degree of flexibility and smoothness of the films of plastics material. This method also requires an expensive feeder which takes the bags individually from the stack and feeds them to the carrier handle fitting apparatus. On the other hand, rotating the individual bags through 90.degree. requires a particular turning apparatus which is of considerable expense in construction and which, again in view of the high degree of flexibility of the film material, can only operate at relatively low bag turning speeds in order reliably to prevent parts of the bags, in particular the corners of the bags, being folded over as they are turned. The means for carrying out the above-described methods take up a not inconsiderable amount of space. They therefore cause an undesired increase in size of the entire installation.

For the above reasons, side-fold bags made of plastics film and bearing carrier handles are still predominantly made in such a way that the side-fold bags are first made and then the carrier handles are welded into the mouth of the bag by hand.

The present invention is based on the problem of providing a bagmaking machine which makes it possible for the carrier handles to be fitted fully mechanically to the mouth of the bag, without the bags changing their longitudinal position, and avoiding the above-mentioned expensive steps which were previously considered necessary to produce side-fold carrier-handle bags in a fully mechanical process.

According to the present invention there is provided a bagmaking machine for making plastics side-fold bags from a stepwise advanced tubular web provided with side folds, including a transverse welding and cutting apparatus for cutting the tubular web into lengths and forming the bottom seams of the bags, a carrier handle fixing apparatus which is controlled such that carrier handles are fed to the leading ends of the cut lengths of tubular web in the opposite direction to the direction of movement thereof and in the plane of movement thereof and there are fixed while the cut lengths of tubular web are at a standstill, and a conveyor which continues the conveyance of the finished bags, the plane of the conveyor being displaced relative to the plane of conveyance of the cut lengths of tubular web such that discharge of the finished bags is not hindered by the carrier handle fixing apparatus.

Insofar as the bottom weld seam is located at the end which is at the rear in the direction of conveyance, of the foremost cut length, the leading opening of the tubular web is available for fitting the carrier handles which can preferably be welded in place on the inside, possibly with special steps being taken to prevent the edges of the bag being welded together, although the carrier handles can also be welded on from the outside. Because the finished bags, immediately after fitting of the carrier handles, are moved for further conveyance into a plane different from the plane of conveyance in the bagmaking machine, the operation of fitting the carrier handles to the respective leading opening of the tubular web is not hindered by the last finished bag so that this proposal according to the invention, which is very simple to carry out, surprisingly solved the problem, the solution to which had already been sought since the above-described plastics bags became known. There is therefore no need for an interpolated operation of stacking the bags before they are provided with carrier handles, nor is a special turning apparatus required.

The conveyor means which conveys the finished carrier handle bags is advantageously arranged below the plane of conveyance of the bagmaking machine. This arrangement of the further conveyor means which comprises a conveyor belt, a sliding plate or the like, has the advantage that the carrier handles are removed from a magazine at the lower end and that the carrier handles secured to the bag guide the bag downwardly due to their weight on to the conveyor means as soon as they are released by the carrier handle fixing apparatus. This arrangement therefore permits easy refilling of the carrier handle magazine while the apparatus is in operation and makes it unnecessary to provide special means to transfer the finished bags to the conveyor means.

In accordance with a further proposal according to the invention, for the purposes of adapting the bagmaking machine to different lengths of bags, the carrier handle fixing apparatus is displaceable in the direction of movement of the tubular web relative to the other parts of the bagmaking machine, while a double-belt conveyor which is variable in length is arranged upstream of the carrier handle fixing apparatus. This design of bagmaking machine makes it possible for the leading end of the tubular web always to be brought into the standstill position at the correct distance from the carrier handle fixing apparatus, irrespective of the length of the bags to be produced, and thus makes it possible for the foremost cut length of tubular web to be supported by means of the variable-length double-belt conveyor during manufacture of the bag, in the variable space between the transverse cutter and the transverse welding apparatus on the one hand and the carrier handle fixing apparatus on the other hand.

In accordance with a preferred embodiment and arrangement of the double-belt conveyor, for the purposes of varying its length, it is provided with direction-changing rollers which are displaceable in the forward direction at its discharge end and, in the region of its idle runs, with loop-forming means which are displaceable transversely to the direction of conveyance and in opposite directions to each other, being in the form of guide pulleys for the two idle runs of the double-belt conveyor, while the direction-changing rollers are mounted on the frame of the displaceable carrier handle fixing apparatus and the loop-forming means are mounted on the stationary frame of the bagmaking machine. The double conveyor belt may then be lengthened or shortened by displacement of the carrier handle fixing apparatus, while the loop-forming means are to be displaced accordingly. The loop-forming means can also be held in their working position by a spring force so that they can readily resiliently follow the variations caused in the loops in the idle runs by the variation in length of the double-belt conveyor.

When this occurs however, the belt tension of the double-belt conveyor varies in dependence on the variation in length thereof, such that it is substantially increased with increasing length and vice versa, considerably reduced, particularly when the variations in length are large. In order to avoid this, in a further embodiment of the invention the two loop-forming means are positively displaceable in opposite directions to each other by means of a common threaded spindle with a portion having a right-hand thread and a portion having a left-hand thread, and the carrier handle fixing apparatus is also displaceable by means of a threaded spindle, wherein the two threaded spindles are connected together by means of a common adjusting gear and the pitches of the two threaded spindles are such that when the carrier handle fixing apparatus and the loop-forming means are simultaneously displaced by means of the common adjusting gear, the belt tension of the double-belt conveyor remains unaltered.

This embodiment of the subject of the invention makes it possible for the bagmaking machine to be rapidly converted to other lengths of bag, using only one adjusting member. It also makes it possible for per se known means for varying the conveyor belt tensions to be provided on the conveyor belts of the double-belt conveyor, which means can be used to set the optimum belt tension in respect of working life and preventing belt slip.

A bagmaking machine in accordance with the present invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows an elevation of the machine,

FIG. 2 shows a plan view corresponding to FIG. 1, and

FIG. 3 shows a side-fold bag with carrier handles, produced by the machine shown in FIGS. 1 and 2.

Referring to FIGS. 1 and 2, in part 1 of the bagmaking machine which is of per se known type, the side-fold bags are produced from a tubular web S which already has the side folds F1 and F2. Included in part 1 of the machine is a pair of feed rollers 3 which rotate intermittently in the working cycle of the machine, a transverse welding and cutting apparatus 4 which extends over the width of the tubular web S and which is reciprocal relative to the tubular web S in the working cycle of the machine by means of the eccentric drive 5, a continuously conveying double-belt conveyor 6 for discharging the side-fold bags, and a stop 8 which is movable upwardly and downwardly in the working cycle of the machine by means of the drive rod 7 and which holds the tubular web S still during the operations of transverse welding and cutting.

The arrangement of the cutting tool and the welding beam in the transverse welding and transverse cutting apparatus 4 is such that the tubular web S is cut transversely downstream of the transverse weld seam in the direction a of web movement.

The cut lengths of tubular web produced are thus removed from the bagmaking machine by the double-belt conveyor 6 in the longitudinal direction, with the open ends, that is the mouths of the bags leading.

Arranged downstream of the part 1 of the machine is a per se known carrier handle fixing apparatus 2 which is provided to secure a respective pair of carrier handles T made of thermoplastics material by welding in the mouth of each bag. The carrier handle fixing apparatus 2 comprises the oppositely movable pair of suckers 9 and 9' for opening the mouth of the bag, a magazine 10 for a stack 11 of carrier handles T, with a slider 12 for removing the lowermost pair of carrier handles T from the magazine 10 and for sliding that pair forward into the mouth of the bag, and a pair of welding tongs 13 and 13' for welding one carrier handle of the pair to the inside of a respective one of the two sidewalls of the bag, at the edge of the mouth thereof.

The pair of suckers 9 and 9' is actuated in the working cycle of the machine by a thrust cam 14 by means of the linkage 15, 16, 17, 18, while the electrically heated jaws of the welding tongs 13 and 13' are opened and closed by means of the thrust cam 19 and the linkage 20, 21. Finally, the magazine slide 12 is driven by the thrust cam 22 by means of the linkage 23, 24, 25.

The arrangement of the carrier handle fixing apparatus 2 relative to the part 1 of the machine is, as is clearly apparent from FIG. 1, such that the working plane of the carrier handle fixing apparatus 2 lies precisely in the working plane E--E of the other parts of the machine. For further conveyance of the bags provided with carrier handles, there is arranged in the carrier handle fixing apparatus 2 below the working plane E--E and at a spacing below the carrier handle magazine 10, a discharge conveyor belt 26 which, as is readily apparent from FIG. 1, extends into the region of the carrier handles T removed from the magazine 10 and held by the slide 12 in readiness for welding, and which discharges the finished bags without their being hindered by the carrier handle fixing apparatus 2 as when they are discharged by means of the double-belt conveyor 6, they simply slide downwardly on to the conveyor belt 26.

The feed rollers 3 each time draw the tubular web S by the length of one bag from a feed roll (not shown) and move it into the region of the transverse welding and cutting apparatus 4, the stop 8 and the double-belt conveyor 6 which rotates continuously at the peripheral speed of the pair of feed rollers 3. The double-belt conveyor 6 moves the tubular web S with its forward open end into the region of the suckers 9 and 9' which are applied upwardly and downwardly to the tubular web S, pull up the forward end of the tubular web S in synchronism with the double-belt conveyor 6 and hold said end open during the subsequent standstill period of the feed rollers 3. During this standstill period, the stop 8 is applied to the tubular web S and holds it still against the pull of the continuously moving double-belt conveyor 6, whereupon the transverse welding and cutting apparatus 4 is advanced towards the tubular web S in order to form the transverse weld seam N (FIG. 3) which forms the bottom of the side-fold bag B, and to separate the bag from the tubular web S.

During these working operations, the magazine slide 12 removes the lowermost pair of carrier handles T from the magazine 10, moving in the opposite direction to the direction a of movement of the tubular web S, towards the end of the tubular web S which is held open by the suckers 9 and 9', and pushes the carrier handles T with their weld-attachment bars into the opening at the end of the tubular web S, as shown in FIG. 1. The welding tongs 13 and 13' then close and weld the two sidewalls of the tubular web S at the edge of the opening thereof, to the two weld-attachment bars of the carrier handles T, so that one carrier handle of the pair is joined to each wall of the tubular web S. The slide 12 then returns to its right-hand starting position, releasing the pair of carrier handles T. The pair of carrier handles T then tips downwardly under the force of gravity on to the conveyor belt 26, while the stop 8 opens and the pair of feed rollers 3 carries out its next feed step. The side-fold bag B provided with carrier handles T and severed from the tubular web S is now deflected by the conveyor belt 26 out of the working plane E--E so as to bypass the apparatus 2, and is discharged by the conveyor belt 26.

As shown in FIG. 1, the carrier handle fixing apparatus 2 must be arranged at such a distance from the remainder of the machine that the distance between the transverse welding and cutting apparatus 4 and the welding tongs 13 and 13' is equal to the length l of the bag to be produced.

In order to adapt the bagmaking machine to other bag lengths, the carrier handle fixing apparatus 2 is mounted on stationary guide bars 27 and 27' so as to be displaceable relative to the part 1 of the machine in the direction a of web movement, and is adjustable by means of the threaded spindle 38.

The double-belt conveyor 6 is also made variable in length. For this purpose, it is provided at its discharge end with direction-changing rollers 28 and 28' which are mounted on the frame of the carrier handle fixing apparatus 2 and which are displaceable therewith, and in the region of its idle runs, with variable loop-forming means 29 and 29'. The loop-forming means 29 and 29' comprise direction-changing rollers 31 and 31' mounted in holders 30 and 30'. The holders 30 and 30' are seated on threaded spindles 32 and 32' which are mounted on the frame of the machine, each of the threaded spindles 32 and 32' having a right-hand and a left-hand threaded portion 33 and 34. The threaded spindles 32 and 32' extend transversely to the direction a of web movement. The idle runs of the conveyor belts of the double-belt conveyor 6 form loops 35 and 35', by passing over stationary guide rollers 36 and 36', and 37 and 37' respectively, and the direction-changing rollers 31 and 31'. The threaded spindles 32, 32' and 38 are connected together by way of a common adjusting gear 39 and are simultaneously rotatable by means of the hand wheel 40. The pitches of their threads are such that when the carrier handle fixing apparatus 2 and the loop-forming means 29 and 29' are simultaneously displaced by means of the gear 39, the belt tension of the double-belt conveyor 6 remains unaltered.

Claims

I claim:

1. A bagmaking machine for making plastics side-fold bags from a stepwise advanced tubular web provided with side folds, including a transverse welding and cutting apparatus for cutting the tubular web into lengths and forming the bottom seams of the bags, a carrier handle fixing apparatus which is controlled such that carrier handles are fed to the leading ends of the cut lengths of tubular web in the opposite direction to the direction of movement thereof and in the plane of movement thereof and there are fixed while the cut lengths of tubular web are at a standstill, and a conveyor which continues the conveyance of the finished bags, the plane of the conveyor being displaced relative to the plane of conveyance of the cut lengths of tubular web such that discharge of the finished bags is not hindered by the carrier handle fixing apparatus.

2. A machine according to claim 1 wherein said means is arranged below the plane of movement of the cut lengths of tubular web.

3. A machine according to claim 1 wherein the carrier handle fixing apparatus is displaceable in the direction of movement of the tubular web relative to the other parts of the bagmaking machine, and a double-belt conveyor which is variable in length is arranged upstream of the carrier handle fixing apparatus.

4. A machine according to claim 3 wherein, for the purposes of varying its length, the double-belt conveyor is provided with direction-changing rollers which are displaceable in the direction of conveyance at its discharge end and, in the region of its idle runs, with displaceable loop-forming means, the direction-changing rollers being mounted on the frame of the displaceable carrier handle fixing apparatus and the loop-forming means being mounted on the stationary frame of the machine.

5. A machine according to claim 4 wherein the loop-forming means are displaceable in opposite directions to each other by means of common threaded spindles with a portion having a right-hand thread and a portion having a left-hand thread, and the carrier handle fixing apparatus is also displaceable by means of a threaded spindle, the threaded spindles being connected together by a common adjusting drive and the pitches of the threaded spindles being such that when the carrier handle fixing apparatus is displaced, the belt tension of the double-belt conveyor remains unaltered.