DE202017007053U1 - Device for producing bags of plastic material - Google Patents

Abstract

A device for producing bags of plastic material with a hot air unit for providing a hot air flow, means (29, 30) for introducing this hot air flow into the area between a preformed tube section (2) and a cover sheet and / or a valve sheet, the tube section and the Cover sheet and / or the valve leaflets by means of conveyors are conveyable and ablatable, characterized by at least one means for supplying a cold air flow in the region between the preformed tube section (2) and a cover sheet and / or a valve sheet or for supplying a cold air flow into the device for introducing the stream of hot air into the area between a preformed tube section (2) and a cover sheet and / or a valve sheet.

Description

The invention relates to a device for producing sacks of plastic material according to the preamble of claim 1.

In the aforesaid devices, hot air sealing devices are used to seal cover sheets and / or valve sheets onto the preformed plastic material hose section. For this purpose, the parameters air pressure and air temperature necessary for the process are set and the machine is started. These parameters often remain unchanged during operation of the devices once they have been adjusted. In particular, these settings often remain independent of the machine speed or the sealing area in the bag section.

However, with ever-increasing machine speeds, it is problematic to find an equal setting of process parameters (air pressure and temperature) for both low and high speeds, which seal topsheets and / or valve leaflets onto the preformed plastic material tube section but do not burn them. However, it is often not possible to change the air pressure and / or the air temperature quickly enough in accordance with the acceleration ramp. In particular, with a slowdown of the machine, the air temperature often can not be reduced fast enough.

The object of the present invention is therefore to provide a device in which a reliable sealing of cover sheets and / or valve leaflets on hose sections is possible even at varying machine speeds, but without damaging them.

The object is solved by the features of claim 1. Advantageous embodiments are specified in the dependent claims. The present invention is based on a device according to the preamble of claim 1 characterized by at least one device for supplying a cold air flow in the region between the preformed tube section and a cover sheet and / or a valve sheet or for supplying a cold air flow into the device for introducing the hot air flow in the area between a preformed tube section and a cover sheet and / or a valve sheet.

In other words, it is provided that a stream of cold air is mixed with the hot air stream, whereby in particular the temperature of the hot air stream is herabsetzbar. This is done either with an additional device directly into the sealing area, which is given by the area between the preformed tube section and the cover sheet and / or the valve sheet, can be introduced, or is introduced into a component of the device for introducing the hot air flow. The difference between these two variants is that in the first case, the hot air and the cold air mix in the seal area, while in the second case, the hot air and the cold air within the means for introducing the hot air flow mix and introduced as an air mixture in the seal area becomes. While the first variant is characterized by a simple structure, the advantage of the second variant is that within the sealing region locally greatly different temperatures are avoided. Under "cold air" or "cold air" is air at a temperature in the range of -100 degrees to 100 degrees Celsius. "Air" or "cold air" is to be regarded as a synonym for any gas or gas mixture. However, preference is given to ambient air, which has been cooled in particular below room temperature. Hot air can also be any gas mixture, in particular ambient air.

The plastic material which can be processed with devices and methods according to the invention is preferably a coated fabric, wherein the fabric has been produced from stretched plastic tapes. The base material for the fabric and / or for the coating is a polyolefinic material, in particular polypropylene and / or polyethylene. In particular, it is advantageous to provide the polypropylene fabric and the polyethylene coating. However, the plastic material may comprise a nonwoven, a coated nonwoven or a plastic film. A plastic film may be multi-layered and include polyethylene, for example.

In an advantageous embodiment of the invention, a fast-switching air valve is provided in all variants of the invention, where "fast switching" a reaction time of the valve of less than 100 milliseconds (ms), preferably less than 50ms and in particular less than 20ms to understand. In this case, it is possible to switch sufficiently quickly to colder air at a throughput time through the sealing range of more than 1000 ms per bag in start-up and set-up mode, in order to avoid burning of the plastic material due to excessive heat input. But even in normal operation, where the cycle time in the sealing area is 500 ms or less, cold air can be added with pinpoint accuracy by using the fast-switching valve. Thus, it may thereby be possible to increase the temperature of the hot air again to allow a shorter flow rate. A higher temperature is possible for the triangular pockets of a crossbeam, but folding edges of the bottom rectangle can be damaged, resulting in the can lead to mentioned edge breakage. By introducing cold air in the area of the ground rectangle, this danger can be reduced.

In a further advantageous embodiment of the invention, it is provided that the hot air flow can be provided with fixed parameters, in particular with a permanently set temperature and / or a permanently set air pressure, in which the cold air flow can be injected. This makes it possible to provide the hot air flow with constant ratios in order to avoid a parameter variation, which, as described above, is very sluggish. The necessary or desired temperature variations in the sealing area are then carried out by supplying a suitable amount of cold air. A supply line for supplying cold air is preferably provided in the means for introducing the hot air flow between a heater and the outlet nozzle of the device to allow a short path of the mixed air in the sealing area. Alternatively, however, it is also conceivable, if, provided that the device for introducing this hot air flow is part of a device for generating a hot air flow and comprises a heating element to arrange the cold air supply in the flow direction of the hot air flow in front of the heater. In this case, it is advantageous to operate the heater with constant power, since a change in power of the heater is very slow. With a cold air supply at this point then the air that is supplied to the heater, a lower base temperature compared with the air without cold air supply, so that the final temperature after passing through the heater is lower. The advantage of such an arrangement is the saving of installation space in the vicinity of the sealing area, which is thus better accessible. This is advantageous in the case of unforeseen problems, since the seal area is then manually reachable. It is also conceivable to replace the rotary valve with such a system. In the case of the "exhaust position" enough cold air is blown in order to reliably prevent a seal. This embodiment will be explained in more detail below.

In a further embodiment of the invention, it is provided that the device for supplying a cold air flow, a compressed air source is connected upstream. Such a compressed air source in particular has a pressure-increasing effect and can be designed as a pump or blower. This makes it possible to supply cold air with a pressure and / or a volume flow, which is higher than that of the ambient air, to the sealing area. In particular, a sufficiently rapid, in particular abrupt, cooling of the air temperature in the sealing area is achieved in order to reduce the overall temperature in the sealing area. The compressed air source can additionally be operated in conjunction with a tempering device in order to be able to change the temperature of the cold air in addition to the pressure or volume flow. This tempering device can be designed as a heater, in particular as a resistance heater, and / or as a cooling device.

With the invention it is also possible to make use of different sealing temperatures during the sealing of a single bag section, which is also conceivable at the maximum machine speed. If it does not come to edge break in the middle part of the bag, can be provided with appropriate adjustment of the air valve (pulse-width modulation) enough cold air to blow in order to lower the air temperature in this period. To the ends, cold air injection can be reduced to re-operate at high temperature, for example to seal the triangular pockets.

• • mit einem Heißluftaggregat ein Heißluftstrom bereitgestellt wird,
• • mit einer Einrichtung zum Einleiten des Heißluftstroms dieser in den Bereich zwischen einem vorgeformten Schlauchabschnitt und einem Deckblatt und/oder einem Ventilzettel eingeleitet wird, wobei der Schlauchabschnitt und das Deckblatt und/oder der Ventilzettel mittels Fördereinrichtungen gefördert- und aufeinander abgelegt werden,

vorgesehen,

• • dass mit einer Einrichtung zum Zuführen eines Kaltluftstroms dieser in den Bereich zwischen dem vorgeformten Schlauchabschnitt und einem Deckblatt und/oder einem Ventilzettel eingeleitet wird oder
• • dass mit einer Einrichtung zum Zuführen eines Kaltluftstroms dieser in die Einrichtung zum Einleiten des Heißluftstroms in den Bereich zwischen einem vorgeformten Schlauchabschnitt und einem Deckblatt und/oder einem Ventilzettel eingeleitet wird.

The above object is also achieved by a method. Accordingly, in a method for producing bags of plastic material, wherein

• A hot air flow is provided with a hot-air generator,
• • is introduced with a device for introducing the stream of hot air into the region between a preformed tube section and a cover sheet and / or a valve sheet, the tube section and the cover sheet and / or the valve sheet being conveyed and deposited on one another by means of conveying devices,

intended,

• • that is introduced with a device for supplying a cold air flow, this in the area between the preformed tube section and a cover sheet and / or a valve sheet or
• • that means for supplying a cold air flow is introduced into the device for introducing the hot air flow in the region between a preformed tube section and a cover sheet and / or a valve sheet.

With this method, the same advantages are achieved, which have already been described in connection with a device according to the invention.

• 1 Seitenansicht einer ersten Variante einer erfindungsgemäßen Vorrichtung
• 2 Seitenansicht einer zweiten Variante einer erfindungsgemäßen Vorrichtung
• 3 Seitenansicht einer dritten Variante einer erfindungsgemäßen Vorrichtung
• 4 Seitenansicht einer vierten Variante einer erfindungsgemäßen Vorrichtung
• 5 Darstellung wesentlicher Schritte zur Herstellung eines Ventilsacks aus einem Schlauchstück

The features mentioned in the claims and in the description of the present patent application may each be essential to the invention individually or in any desired combination. In addition, advantages, features and details of the invention will become apparent from the following description, in which reference to the figures, various embodiments are explained in detail. Within the scope of the entire disclosure, features and details described in connection with the method according to the invention apply, of course also in connection with the device according to the invention and in each case vice versa, so that reciprocal reference is always made to the disclosure of the individual aspects of the invention can. Also, individual features, even if they are described or have been described only in connection with other features, taken by itself be essential to the invention. Therefore, such features are considered to be combinable with any other disclosed features. The individual figures show:

• 1 Side view of a first variant of a device according to the invention
• 2 Side view of a second variant of a device according to the invention
• 3 Side view of a third variant of a device according to the invention
• 4 Side view of a fourth variant of a device according to the invention
• 5 Representation of essential steps for producing a valve sack from a piece of hose

A device according to the invention can be found in the in DE 195 02 255 C2 . 1 , disclosed device. In the production of bags made of coated plastic fabric hoses several process steps are necessary, which later on the basis of 4 be explained in more detail. In particular, for connecting various components of the later bags corresponding workstations are provided. Specifically, these are: a work station for applying valve leaflets, work stations for closing the floors, and work stations for applying ground cover sheets which hold together the floors of the bags. The use of workstations for applying the bottom cover sheets may possibly be dispensed with. Other workstations are conceivable.

In general, except for the workstation for applying valve leaflets, the workstations are made double, so that the corresponding work can be performed simultaneously at both ends of the hose pieces, which are usually conveyed transversely to their longitudinal tube axis. The number of work stations for introducing the valve leaves or hoses may differ from this rule, depending on the desired number of valves.

The 1 now shows the side view on such a workstation 1 in a device according to the invention, which is a workstation for applying bottom cover sheets 3 . 3 ' on sacks 2 is. The transversely conveyed sacks 2 lie on a table 4 on and are transported by a suitable, not shown in this figure transport in the transport direction z. The already added floors are also placed in the plane of the table. However, the invention is not limited to this, but the floors can also lie in a plane which is orthogonal to the plane which is spanned by the table level.

About a feed 5 becomes the workstation 1 a web material 6 supplied, from which the ground cover sheets 3 . 3 ' be separated. This is the leading end of the web material 6 from the cutting cylinder 7 and the conveyor belt 8th recorded and pulled forward and by the cutting cylinder 7 integrated, but not shown in detail cutting device 9 cut across. The resulting ground cover sheet 3 . 3 ' is from the suction cylinder 10 taken over and on the bottom of the bag 2 placed. The suction cylinder 10 forms with the impression cylinder 11 a nip 12 , In this way, the ground cover sheet becomes 3 ' on the bag 2 pressed with high force. In the 1 is already part of the bag 2 with overlying ground cover sheet 3 ' passed through the nip. In the inlet area of the nip 12 is a facility 13 arranged to generate a hot air stream whose hot air flow 18 in the inlet side of the nip 12 is directed. The hot air causes the coating to melt both on the bottom of the bag 2 ' as well as on the ground cover sheet 3 ' , It will, as the 1 can be removed, the coatings of the surfaces melted or plasticized, which are brought together immediately thereafter. The bringing together of the surfaces with the still fused coating material takes place in the nip 12 so that the coatings now form an intermediate layer, which can be regarded as homogeneous, between the ground cover sheet and the ground, which permanently binds said constituents after cooling. Due to this process, the inlet area of the nip can be referred to as a sealing area. The cylinders 10 and 11 turn in the direction of the arrows R and R ' ,

The device for generating a hot air stream 13 initially includes as a central element a hot air blower 20 which includes a fan with integrated or downstream heating means. The intake of ambient air via the line 21 which can be configured in particular as a hose. Seen in the conveying direction of the hot air behind the hot air blower 20 is an optional rotary valve 22 provided with which of Hot air flow can be interrupted. In particular, the hot air flow, when it is not needed (ie in the periods in which no bag is the sealing area), deflected and released to the environment. The rotary valve 22 can by means of a piece of pipe 23 from the hot air blower 20 be spaced. The hot air stream now enters a nozzle 24 Preferably, this hot air flow to the width of the bottom of the bag 2 disseminated while targeting him on the inlet region of the nip 12 focused.

To realize a cold air supply, can in the nozzle 24 an opening may be provided into which a cold air supplying pipe 25 or hose can open. This pipe 25 or this hose can be a quick-acting valve 26 include, with which a cold air flow can be interrupted or transmitted. Furthermore schematically shown is a pump or a fan 27 , which is intended to put the cold air under sufficiently high pressure, so that after opening the fast-switching valve and the cold air flow directly the inlet region of the nip 12 achieved there by mixing the temperature of the hot air stream lowers. Not shown is a tempering, with which the temperature of the cold air flow can be influenced.

In the further embodiment of the invention according to 2 can on the rotary valve 22 be dispensed with, since now with the cold air supply sealing can be suppressed as well as with the discharge of the hot air due to the operation of the rotary valve 22 ,

The 3 now shows a variant of the 1 in which the pipe or hose 25 not in the area of the nozzle 24 ends, but with its own nozzle 28 is provided. With this nozzle 28 the cold air flow can be introduced directly into the sealing area. This arrangement has the advantage that it can be retrofitted to existing machines.

The 4 Now shows a further embodiment of the device according to the invention, in which the hose or the pipe 25 into the pipe 21 opens and thus supplies a cold air flow in order to cool the supplied air flow from the environment can. The resulting effect has already been described above.

The 5 finally clarifies the steps for the molding of soils to the later bag 2 , first as a piece of hose 40 is present, wherein the hose piece by means of the transport device 41 to the individual stations, with which the steps for molding floors on hose pieces are feasible, can be brought. In the illustration a), at least one end, preferably both ends, of the piece of tubing is raised, the upper layer being along the bottom center line 42 is folded back so that the bottom rectangle 43 and the triangular pockets 44 form. In this illustration, the second folding edges are with dotted lines 45 drawn to the the side flaps 46 . 47 , with which the areas are designated beyond the second folding edges, are folded over.

To these second folded edges are in step c) and d) the side flaps 46 and 47 folded, which is preferably slightly offset in time, so as not to cause a disturbance. It is now a covered ground 48 emerged. In step b) was previously still on a triangular pocket a so-called valve sheet 49 attached, which later provides an opening for filling the finished bag.

In the final step e) is now a cover sheet 50 attached to the bottom of the bag so that both side flaps are connected with each other and with the triangular pockets adjoining on both sides.

The second, optional floor 51 was produced in the same way and preferably simultaneously, but without introducing a valve.

LIST OF REFERENCE NUMBERS

1

workstation

2

bags

3, 3 '

Floor Covers

4

table

5

Intake

6

sheeting

7

cutting cylinder

8th

conveyor belt

9

cutter

10

suction cylinder

11

Impression cylinder

12

nip

13

Device for generating a hot air stream

20

Heat Guns

21

management

22

rotary vane

23

pipe section

24

jet

25

pipe

26

Valve

27

fan

28

jet

40

hose Connector

41

transport means

42

Bottom center line

43

bottom square

44

triangle bag

45

folding edge

46

side flap

47

side flap

48

Approved ground

49

valve List

50

cover sheet

51

Second, optional floor

R, R 'Z

transport direction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19502255 C2 [0015]

Claims (4)

A device for producing bags of plastic material with a hot air unit for providing a hot air flow, means (29, 30) for introducing this hot air flow into the area between a preformed tube section (2) and a cover sheet and / or a valve sheet, the tube section and the Cover sheet and / or the valve leaflets by means of conveyors are conveyable and ablatable, characterized by at least one means for supplying a cold air flow in the region between the preformed tube section (2) and a cover sheet and / or a valve sheet or for supplying a cold air flow into the device for introducing the stream of hot air into the area between a preformed tube section (2) and a cover sheet and / or a valve sheet. Device after Claim 1 , characterized in that the device for supplying a cold air flow comprises a valve which has a reaction time of less than 100 ms, preferably less than 50 ms, in particular less than 20 ms. Device according to one of the preceding claims, characterized in that the hot air flow with fixed parameters, in particular with fixed set temperature and / or a fixed set air pressure, can be provided, in which the cold air flow is inflatable. Device according to one of the preceding claims, characterized in that the device for supplying a cold air flow upstream of a compressed air source.

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