Delivery device for bags with freshly glued bases

A delivery device is disclosed for bags having freshly glued bases. A series of squeeze cylinders and endless squeeze belts are provided to define a conveying path having the shape of a twin S. As a procession of bags traverses each cylinder, the opposite bag edges are squeezed between pairs of the belts.

BACKGROUND OF THE INVENTION 
This invention relates to a delivery device for bags with freshly glued 
bases and which comprises at least one twin belt conveyor adapted to 
squeeze the bottom parts of the bags with endless pressing belts. 
The freshly glued bases of bags have to be squeezed directly after they 
have been produced in order to prevent the bases from becoming unstuck and 
unfolding and to produce satisfactorily bonded or glued bases by pressing 
on the bottom parts of the bags. 
A delivery device of this type is disclosed in German patent 1,298,873. The 
device has two belt conveyors, consisting of pressing belts, for a stack 
of the bags which had just been produced, the device operating such that 
the pressing belts squeeze the bottom parts of the bags. Since the 
pressing action has to be maintained for a sufficiently long time, the 
twin belt conveyors pressing on the stacks have to have a considerable 
lengths and this leads to an undesired bulkiness of the plant for 
producing such bags. 
SUMMARY OF THE INVENTION 
One object of the present invention is to devise provide a bag delivery 
device which has a short overall length. 
In accordance with the invention, the twin belt conveyor has endless 
squeeze belts which are arranged in vertical planes on top of each other 
and are adapted to take up the bags in overlapped succession between them. 
The conveyors are trained around at least two squeeze cylinders defining a 
conveying path in a letter S configuration, or in the case of there being 
more than two squeeze cylinders, defining a conveying path with a multiple 
letter S configuration. 
In the delivery device in accordance with the invention, a conveying path 
with a single or multiple letter S configuration is provided for squeezing 
the overlapped procession of bags so that the overall length of the 
squeeze path may be considerably shortened. 
It is convenient if two pairs of squeeze cylinders having endless squeeze 
belts trained around them and each with a letter S conveying path are 
provided. This arrangement makes it possible to arrange sections of the 
squeeze path in a plurality of planes so that there is an additional 
reduction of the length of the plant. 
In accordance with a further convenient feature of the invention the pairs 
of squeeze cylinders are arranged approximately symmetrically about a 
vertical plane which is parallel to the axes of the squeeze cylinders. In 
this respect it is possible for two respective squeeze cylinders of the 
two cylinder pairs to be placed nearer and farther from the plane of 
symmetry. 
In accordance with a further feature of the invention the design is such 
that each of the squeeze cylinders is provided with its own squeeze belts. 
In this case the arrangement is then preferably such that the output ends 
of the twin belt conveyors--consisting of the squeeze belts --of the 
preceding squeeze cylinder, transfer the overlapped bags to the intake gap 
of the twin belt conveyor of the following squeeze cylinder. In order to 
ensure a properly aligned conveyance of the overlapped bags, the 
respectively outer squeeze belts of the twin belt conveyor are preferably 
idler belts. 
The conveyance of the overlapped bags by a twin belt conveyor with endless 
upper and lower runs, which pass over two spaced bend cylinders, is 
disclosed in German patent 530,526. Between the two bend cylinders, the 
two runs of the twin belt conveyor form a straight conveyor path, along 
which the runs are moved at different speeds, because on passage over the 
bend cylinders the respectively outer runs are caused to move at a higher 
speed. Owing to the speed differential between the two conveyor runs of 
the twin belt conveyor the overlapped bags are drawn together so that the 
spacing and the settings of the individual bags in the overlapped 
procession thereof are irregularly altered. 
In the delivery device in accordance with the invention there is 
fundamentally a requirement for the overlapped bags being conveyed on the 
squeeze path to be drawn apart with an increase in the distance between 
and pulling apart of consecutive overlapped bags in order to overcome any 
tendency of the superposed bags to be stuck together by glue dripping or 
being squeezed out of the seams. In accordance with a further feature of 
the invention the device is accordingly so designed that the squeeze belts 
of the twin belt conveyors pass around at least one following squeeze 
cylinder at a higher speed than the speed of a preceding squeeze cylinder. 
This higher speed causes the overlapped, superposed bags to be drawn apart 
with a regular, even increase in the pitch of the overlapped bags so that 
any tendency of the bags to adhere together is decreased. Since the bags 
are conveyed by a preceding twin belt conveyor so that their leading edges 
separately enter the intake nip of the twin belt conveyor running at a 
higher speed, the individual bags are drawn from the arriving procession 
of overlapped bags with an increasing overlap pitch without their being 
displaced in any other way so that the only change in the overlapped 
procession is that the pitch is increased. 
It is convenient to provide a twin belt conveyor, consisting of squeeze 
belts and having a straight path, to feed the squeeze cylinder running at 
a higher speed. It is then convenient if the squeeze belt, forming the 
lower run, of the straight path is trained, as the inside belt, around the 
following squeeze cylinder, the uppers that is to say outsider squeeze 
belts of the straight conveying path and of the following squeeze cylinder 
being separate from each other. This prevents the squeeze belts of the 
twin belt conveyor running at different speeds in relation to each other 
in the straight conveyor path. 
In a case in which there are two pairs of squeeze cylinders, it is 
furthermore expedient if the last pair of the squeeze cylinders revolves 
at a higher speed. 
Since the overlapped bags only have to be squeezed together in the bottom 
parts thereof, the squeeze belts may only be arranged adjacent of the two 
bottoms of the bags. In this case the overlapped bags are conveyed with 
transverse alignment so that the bottom parts thereof are to the outside, 
that is to say at the sides of the overlapped procession of bags. 
A further possible feature of the invention is such that two outer separate 
squeeze belts are provided adjacent to the bottom parts of the bags, such 
belts being associated with the bottom parts with their different number 
of plies. This feature takes into account the fact that the outside parts 
of each bottom have less plies, for instance only two plies, whereas the 
bottom part overlapping a bag wall is thicker owing to the presence of the 
plies of the two bag walls.

DESCRIPTION OF PREFERRED EMBODIMENT 
In the rear wall 1 of a frame, whose front wall is not shown, four idling 
squeeze cylinders 2, 3, 4 and 5 are mounted as shown in FIG. 1. The first 
cylinder 2 has a first driven pair 6 of axially spaced belts trained about 
it over a major circumferential angle, such belt pair being extended as an 
intake belt 6'. In the part, in which the belt pair 6 acts as an intake 
belt pair 6' a further belt pair 7 is associated therewith so that the 
overlapped procession arriving in the direction A assumes a position 
between the belt pairs 6' and 7. Adjacent to the output end of the belt 
pair 7 there is a further idler belt pair 8, which is trained around the 
cylinder 2 over a major angle just like the belt pair 6. The belt pair 8 
is in this respect guided by guide pulleys 9, of which one pulley 9' may 
be displaced in the direction of the arrow B for altering the tension of 
the belt. After an overlapped bag procession has moved around the cylinder 
2, the procession passes between two belt pairs 10 and 11, trained around 
the cylinder 3 over a major angle, the belt pair 11 being driven and 
running directly on the cylinder 3. The belt pair 10 has guide pulleys 12, 
one of which 12' is able to be shifted in the direction of the arrow C in 
order 30 to modify the tension of idler belt pair 10. For this purpose a 
support pin 13 of the guide pulley 12' is held in a longitudinal groove 14 
so that the guide pulley 12' may be changed in position using a piston and 
cylinder unit 15. Adjacent to the output end of the belt pairs 10 and 11 
there are further belt pairs 16 and 17, both of which are driven and of 
which the belt pair 16 is trained around the squeeze cylinder 4 over a 
major angle. Adjacent to the zone of such training of the belts an idler 
belt pair 18 engages the belt pair 16. A support pin 20 of a guide pulley 
19 is mounted in slots 21 to be adjusted in position by piston and 
cylinder units 22 in order to change the belt tension. Just as was the 
case with the cylinder 4, the further squeeze cylinder 5 following it has 
a belt pair 23 trained about and resting directly on it, and an outer belt 
pair 24 on the part with an effective conveying action. Just as is the 
case with the squeeze cylinders 2, 3 and 4 the belt pair 23 (which is 
directly trained about the cylinder 5) is driven, while the outer belt 
pair 24 is freely entrained, i.e. idles. Of the guide pulleys of this 
outer belt pair 24 the guide pulley 25 is able to be adjusted in the 
direction of the arrow D in order to reset the tension of the outer belt 
pair 24. The procession of overlapped bags leaving the squeeze cylinder is 
then removed by further belts 26. 
In the illustrated embodiment, the belt pairs 6 and 11 trained about the 
cylinders 2 and 3 are driven at the same speed, while the inner belt pairs 
16 and 23 directly trained about the cylinder 4 and 5 on the surface 
thereof are driven a speed which is slightly above that of the belt pairs 
6 and 11. This feature ensures that an increase in pitch of the overlapped 
bags coming from the cylinder 3 is precisely effected, such increase 
taking place as the overlapped procession is received between the belt 
pairs 16 and 17. It will be seen from FIG. 2 that the belt pair 18 
consists of two belts or belt elements, whereas in the embodiment shown in 
FIG. 3, the idler outside belt pair partly trained about the cylinder 4 
consists of four individual belts or elements 18' to 18"". The embodiment 
in accordance with FIG. 3 offers the advantage that the tensions of the 
belts 18' through 18"" may be individually reset in a manner to suit the 
thickness of the bag base. Adjacent to the belts 18" and 18"' the base 
consists of four plies, while adjacent to the belts 18' and 18"" it is 
composed of only two plies. In the case of very thin material this 
difference is of no great import so that the embodiment of FIG. 2. may be 
used. If however a bag is to produced consisting of very thick material, 
it is preferable to adopt the design in accordance with FIG. 3. In the 
case of the example in accordance with FIG. 3, it is necessary to provide 
a plurality of the piston and cylinder units 22. Although FIGS. 2 and 3 
are only related to the squeeze cylinder 4, it is clear that the outside 
belt pairs 2, 3 and 5 could be designed in a similar manner. 
In the illustrated working embodiment of FIG. 4, the broader belts of the 
belt pair 18 have respective narrower belts 50 bearing on them, which are 
only located adjacent to the outer base parts of the bags with a lesser 
number of plies so that this base part is also subject to a thrust which 
is approximately equal to the thrust acting on the inner base part, which 
owing to the overlapping bag walls has a larger number of plies. 
The additional belt pair 30 may be provided for all 20 cylinders 2 through 
5, or however only for individual cylinders. 
In order to allow the tension of the squeeze belts to be adjusted to 
respective working conditions, the squeeze belts may be arranged to be 
adjusted independently for each cylinder. 
If no squeeze belts with a major tension or if additionally squeeze belts 
are provided, for the outer base parts of the bags, they are loaded by a 
smaller thrust owing to the smaller number of plies. It is thus possible 
to select squeeze belts which have such a high elasticity that despite the 
different numbers of plies in the two base parts, they exert approximately 
the same thrust on the entire base part.