DE10114601A1 - Sack and box stack cover film manufacture involves air cooling a transverse weld on a tubular film from below and cutting the tube adjacent to the weld from below - Google Patents

Abstract

A continuous side-folded tubular plastic film (2) for use in a stretched cover packaging machine is transversely welded (25). A cooled air flow at a temperature well below that of the welding temperature is then blown from the underside onto the welded area. The tube section incorporating the weld is then cut from the continuous tube immediately adjacent to the weld line to form a cover (2'). An Independent claim is made for a welding, cooling and cutting head (1) for production of a plastic film cover which includes a welded seam cooling system (26) comprising two hollow air tubes (38), one on each side of the tube (2) below the welding bars with nozzles (27) facing upwards at an angle towards the tube faces (5).

Description

The invention relates to a method for producing (film) hoods from one Plastic film existing, i. a. from foils fed from a reeled hose supply hose, esp. a gusseted hose, esp. for (further) use in a pack kungsmaschine, esp. a stretch hood packaging machine, in which the (i. a. i. w. verti Kal arranged film tube each to form a (film) hood with one of the desired / required hood length corresponding distance to its free end provided a cross weld, and above the cross weld formed by the Hose is separated, and in which the provided with the cross weld, or Cross section weld hose section after formation of the cross weld seam - in front  preferably on its two opposite sides - by blowing on a gas (generally air) is cooled, the temperature of which is applied to the with the cross-welded hose section (preferably considerably) lower is (e.g. at least normal room temperature, preferably lower) than sweat seam temperature immediately after formation of the weld seam.

The present invention further relates to a device for producing (foil) Hoods made of a plastic film, i. a. from a coiled hose supply supplied hose, esp. a gusseted hose, esp. for a packaging machine, esp. a stretch hood packaging machine, esp. for packaging / wrapping of cuboid or cube-shaped stacks of goods or the like, with a guide device for supplying a hose section from the hose supply to form a respective one (Foil) hood, a welding device with heatable welding elements such as welding bake or strips or the like. To form a cross weld at the free end portion of the supplied hose section, one above and adjacent to the welding device arranged cutting device, by means of which the provided with the cross weld Hose section to be separated from the hose to form a hood, an upper Half of the cutting device arranged, drivable (first) clamping device, by means of which the hose adjacent to the separation line i. w. pinch across its width, one arranged below and adjacent to the welding elements of the welding device Neten, drivable second clamping device, by means of which the hose i. w. over his Width is to be clamped, and with a cooling device by means of which the cross welded hose section after welding the cross weld is cool, to carry out the aforementioned method.

Various methods and devices are known, by means of which, for example filled sacks, boxes or the like. existing, i. a. cuboid stack of piece goods each with a foil hood are to be wrapped to counter them on their top and side surfaces  Protect weather influences or other environmental influences, and one for them Giving sufficient stack strength required for transport.

This was initially done until around the late 1980s i. w. so-called shrink hoods used, and - after a devastating accident, its cause in the heat required for the shrink hood packaging technology lay of the shrink films - then mostly so-called stretch hoods.

In the former case, the (shrink) film hood has a slightly larger circumference than the stack of general cargo to be wrapped up, and after pulling the hood over the stack to be wrapped is shrunk onto the stack by the application of heat. at the use of stretch film material, on the other hand, shows the (stretch) hood to a considerably smaller extent than the piece goods stack to be wrapped, is stretched to a slightly larger circumference than the stack circumference before covering, and, after covering the hood, lies over the stack to be wrapped due to the in the state of covering existing elastic stretch of the film material firmly on the piece stack of goods.

In both cases, the film covers are usually made from a so-called gusseted tube manufactured, which is folded flat when stored, so that two V- shaped folds lie between two parallel wall sections.

For hood formation i. a. one of the i. a. reel of hose reeled into a roll unwound hose section to an i. a. integrated into a packaging machine Hood formation facility led and i. a. vertically down through this, so that the manufactured film hoods immediately continue to work in the hood formation state turns, d. H. below the hood formation device expediently from above can be drawn over the piece goods to be wrapped below.  

The production of film hoods takes place i. a. i. w. so that the i. w. vertically through the Hood forming device with a desired length of the hose forming hood corresponding distance to its free end with a cross weld provided and then above the cross weld using a separating or cutting unit direction is separated from the hose supply.

The cross weld seam is usually made with two parallel, heatable ones Welding strips or the like. Having welding device, the welding elements under mutual pressure on the foil sections to be welded and opened The welding temperature (of the foil material). Before the separation, the free Hose end i. a. expediently already from fingers, grippers or similar elements ten of the packaging machine so that the finished film hood to avoid unnecessary dead times and thus to achieve the greatest possible packaging performance can be processed immediately after the hood formation.

Especially if the hood formation forms part of the entire packaging cycle, it must also be possible to carry it out as quickly as possible, because otherwise it Packaging performance of the entire machine adversely affected.

A production of plastic film hoods from hose material is therefore not un problematic because the film material in the weld area during the welding process is so strong must be heated so that it assumes a viscous, doughy state in which the actually pass through each other to form a weld seam gig, firmly and permanently welded together so that it can be seen tearing or tearing can occur in the weld area, if only slight forces arise in this state act on the softened film.

It is therefore necessary to cut off the hose provided by the cross weld wait until the film material is sweaty  has solidified the seam area again, otherwise it will come off when it is cut off forces exerted on the film can damage the weld seam, if it is still trapped in the welding device.

Since it has been shown that it creates a clean, parallel to the cross weld running dividing line is advantageous if the film tube on both sides when cutting is clamped (clamped) adjacent to the intended severing line, and that thereby the forces exerted on the weld seam area when cutting off are also less than when the film tube is only inserted in the welding device when it is cut off is stuck, a hood formation device has already been created, in which A corresponding clamping device is present above the cutting device, by means of which the hose is also to be pinched when disconnecting.

Nevertheless, even with this method of working, there may still be imperfections in the area of the weld seam come if it is not waited until the detachment, until the from the Welding device has clamped the weld seam cooled so far that it is back has assumed a solid state.

But even if you take this relatively long cooling-off time - and therefore one too Lower throughput - in the end, it can damage the film in the weld seam come rich. This is probably based on a. on the fact that the weld from downward extending hose section due to its weight even then certain train can exert forces on the weld area when it is at its lower end portion is already picked up by fingers, brackets, grippers or the like, these forces in particular when Larger hoods to be formed are apparently sufficient to be immediately adjacent to the heater ten clamping point of the welding device to exert adverse effects on the film.

The main reason for such damage is likely to be that the thickness of the Weld seam considerably smaller than the sum of the thickness of the welded together  Foil layers will be when the sealing strips under mutual pressure on the Welding temperature heated the weld area also during its cooling phase keep clamped. This not only makes the weld seam correspondingly thin, but it too arise at the longitudinal edges of the weld, which is the transition to the thicker Film areas form, apparently notch effects when there is an exposure to it impressed mechanical stresses comes.

In a method known from EP 0 796 789 A1 and a corresponding device device is therefore provided that the hose before welding until after disconnection is additionally clamped below and adjacent to the welding point over its width. The corresponding device is therefore designed so that below and adjacent to the Welding elements a second clamping device is arranged, by means of which the Hose i. w. across its width must also be clamped in order to match the generic Method or the generic device according to. EP 0 796 789 A1 a larger one To achieve throughput without causing damage in the weld area comes, with this method / this device also a possibility for this should be created to improve the strength of the weld.

The above-mentioned document also provides for the cross weld to cool after their formation - preferably on their two outer sides - and before inflated by blowing with air. In this known device is therefore a cooling device device provided, by means of which the cross weld after opening the weld direction with a coolant such as air Compressed air source is to be connected, and has outlet openings from which the cross blow the weld seam in a controlled manner at the appropriate time, when the welding you removed.

It has been shown that the desired goals are fundamentally with these measures to achieve, or to ver the results previously achievable in the prior art  were better that the cooling time of the cross weld seam formed compared to that previously cooling time achievable without cooling could be significantly reduced, namely (of course depending on the type and thickness of the film material used) for common stretch films s to an average of 12 s, but this value can be achieved in the meantime total cycle time of approx. 30 s (with more than a third) is still relatively high. There one continues to strive for the throughput, i.e. the packaging performance of a stretch hood packaging machine, if possible to increase, and time savings for the rest Steps of the packaging process hardly seem to be possible, so far to no avail - attempts to reduce the cooling time even further in order to reduce the cycle time to reduce speaking, and thus increase the packaging performance accordingly. Stretch hood packaging machines with an hourly throughput of 120 loading units units that are now often urgently required by users, So far, however, could only be achieved by using a flaccid skin bendeckel worked, so not (like the hood side walls) when pulling under offset (biaxial axial) tension, and also did not work with a biaxial stretch, d. H. the hood side walls when pulling the hood over the one to be wrapped In addition to the horizontal horizontal stretch imprinted on them, stack a vertical length stretch of at least 5% (see EP 0 344 815) in order to achieve optimal loading to create units in which even after a long storage period and possibly multiple Envelope and the associated subsequent venting of the piece goods (e.g. with Cement filled bags) is still excellent stack strength.

The present invention is according to based on the task, the known methods and to improve the facilities of the genera described above, in particular in that that significantly reduce the cooling time of the cross weld and thus the packaging performance (throughput) must be increased accordingly, even if with a bia xial (horizontally) tensioned hood cover and / or biaxially tensioned hood side walls working in the finished wrapping condition of the loading units.  

The procedural part of the above object is achieved according to the invention characterized in that the tube section having the transverse weld seam only from below with the (Cooling) gas is blown.

While the subject of EP 0 796 789 A1 (see FIG. 6), which was already mentioned above, provided that the hose section having the transverse weld seam be obliquely blown from above on the other side, and in the generic method or the generic device according to. US Pat. No. 4,999,974 A1 intended to blow the weld seam region on both sides of the film from above and below, as was later adopted in an identical manner in DE 93 16 778 U1 for a generic method, it has been shown that considerably better results in the sense of the above task - with otherwise the same / comparable conditions - can be achieved if the hose area containing the welded area is blown on only from below (and not additionally from above), especially when this occurs heated cooling gas after its heating through the weld area of the film (and its corresponding cooling - preferably upwards and / or laterally) is sucked off. In this way of working / with such a device, the cooling time is surprisingly reduced to about 1/4 - 1/6, for example, from approx. 12 s to (good) 2 s, i.e. with a cycle time of approx. 30 s from approx. 40% to just under 7%. This results in a theoretical increase in throughput from a whopping approximately 50% after a corresponding conversion by shortening the cycle time from approx. 30 s to a good 20 s, in any case - even if these theoretical values have not yet been fully achieved in practice be achieved - an unexpected and difficult to believe improvement.

The technical reason for this very significant improvement is not yet in all Details known. Blowing the cross weld seam is expected to result the hose section from below and above to flow unfavorable for cooling purposes ratios of the (cooling) gas, whereby this is at least prima facie surprising,  because turbulent gas flows per se compared to largely laminar flows i. a. are superior in terms of cooling technology.

On the other hand, the very considerable improvement in the cooling effect is with a corresponding decrease setting of the cooling time when the film having the weld seam is blown on looking from below instead of from above looking more understandable, because it also means that of the weld seam just formed immediately adjacent film area of the after the Ab separate the hood-forming hose section is cooled considerably more intensely than when blowing from above (i.e. above the weld seam). Because the intensely ge cooled, the weld seam upward adjacent tube section is after completion of the hood formation process is initially not claimed in any way, because it affects him around the lower end section of the hose supply existing after hood formation delt, while the hose area below the weld seam shortly after the house benbildung is already subjected to very considerable (horizontal) tensions when opti Male loading units are to be created whose hood covers do not sag (at least not significantly biaxially stretched horizontally) on the top of the stack, but (if necessary considerably).

The furnishing part of the above object is achieved according to the invention by the characterizing features of claim 7, wherein preferred embodiments the invention - both procedural and institutional type - in the Unteran sayings are described.

The invention is further illustrated below using exemplary embodiments with reference to a drawing explained further. It shows

Fig. 1 is a vertical sectional view of a stretch hood packaging machine (detail: s 7 and 8..) In the field of welding, cutting and Kühlein direction in the opened state of rest;

Fig. 2 shows the representation. Figure 1 in the closed-welded condition.

Fig. 3 shows the representation. device of Figures 1 and 2 in the still closed clamping condition with already re-opened welding device shortly before the separation of the thereafter, the hood forming a tube section, and with active cooling.

Fig. 4 shows a variant according to a representation. Fig. 1;

Fig. 5 shows the representation. Fig. 4 in an operating state. Fig. 2;

Fig. 6 shows the representation. FIGS. 4 and 5 according to a state. Fig. 3;

Figure 7 is a schematic partial side view of the essential elements of a hood forming device and some components of the associated packaging machine Ver seen in the direction of section line VII-VII in Fig. 8. and

Fig. 8 is a reduced plan view of the device acc. Fig. 7 seen in the direction of section line VIII-VIII in Fig. 7.

Fig. 7 shows a highly schematic, partial side view of essential components of an overall designated 1 hood formation device, which is integrated in a packaging machine for the respective wrapping of piece goods with a film hood 2 '. From the packaging machine only a few components arranged above the hood formation device 1 are indicated.

A gusseted tube 2 consisting of a plastic film runs horizontally from a supply roll (not shown), initially in the flat folded state, to a deflection roller 3 , from which it is deflected so that it then runs vertically downwards, from wedges 4 arranged in a stationary manner on the packaging machine , which engage in the side folds, slightly spread out, as can be seen in FIG. 8, and in this state runs through the device 1 with two wall sections 5 which continue to run parallel to one another and the slightly open side folds 6 'between them.

At its lower end, not shown, the tube 2 is received by elements, not shown, which open it there completely at the appropriate time, in the case of stretch film material - generally used on these (reef and stretch) elements - on that for covering the in the Device 1 formed hood 2 'stretch required overdimension, and pull the hood 2 ' over the stack of items to be wrapped, which is also not shown in FIGS. 7 and 8. Since this is well known to the specialist world and is insignificant in its details for the present invention, an illustration and further description of these and other elements of the packaging machine have been dispensed with.

It should only be pointed out that in FIG. 7 the packaging machine still indicates grippers 6 arranged between the wedge plates 4 and the device 1 , which grips the side gusset tube 2 , which is slightly opened by the wedge plates 4, at its outer longitudinal edges.

The device 1 has two arranged at right angles to the hose longitudinal direction, beheiz bare welding strips 7 and 8 which are arranged parallel to the parallel wall sections 5 of the gusseted tube 2, and along a welding means form means of which the hose 2 with a direction perpendicular to its longitudinal direction transverse weld 25 is to be provided. The welding strips 7 and 8 are each arranged on the inside of a U-shaped clamping frame 9 and 10 . The clamping frame 9 has at its upper edge to a top terminal block 11 and at its lower edge a lower terminal strip 12, while the clamping frame 10 is provided at its upper edge with a top terminal block 13 and at its lower edge with a bottom clamping bar fourteenth The clamping surfaces 15 of the two clamping strips 11 , 12 and 13 , 14 arranged one above the other are in alignment with one another and are in the rest position of the device 1 shown in FIGS. 7 and 8 and FIGS. 1, 3 and 4, 6 respectively internally directed contact surface 16 of the associated welding bar 7 and 8 offset. In any case, this is in accordance with the training. Fig. 7 the case, while according to the training. are aligned in Figs. 1-6 also to the contact surfaces of the welding strips 7, 8.

At the front ends of the clamping frame 9 , 10 , a guide piece 17 is fastened, which is guided on a linear guide 18 , and is connected to a whole with 19 be designated drive, by means of which the clamping frame 9 , 10 from their in Figs. 7 and 8 shown rest position together with the welding strips 7 , 8 arranged on them in the direction of the arrows 20 are to be moved synchronously up to approximately the vertical central longitudinal plane 21 of the device 1 . The drive 19 can consist of piston-cylinder devices or can be realized in another way. It doesn't depend on his specific training. It is only essential that the drive 19 is able to move the clamping frames 9 and 10 from their rest position into a clamping position (and back again into the rest position), as will be explained further below with reference to FIGS. 1-6 , in which the upper clamping bars 11 , 13 forming an upper clamping device and the lower clamping bars 12 , 14 forming a lower clamping device firmly clamp the hose 2 . Here, the two welding strips 7 , 8 have reached this clamping position during training acc. FIGS. 7 and 8 yet a mutual distance from one another.

Although the welding strips 7 , 8 can be moved together with the clamping frame 9 , 10 , they each have their own separate drive 23 or 24 , by means of which they can be moved relative to each other relative to their clamping frame 9 or 10 until they are under Clamping the hose 2 each have a section 5 of the hose 2 running parallel to them, and clamp this between them.

The heatable welding elements 7 'and 8 ' are already heated to the required welding temperature of approx. 140 ° C., so that the welding strips 7 , 8 only engage in clamping engagement with the hose 2 over a period of approx. 0.8 s need remains, to form the transverse weld 25, and thereafter immediately by means of the drives 23 and 24 are moved back to the clamping frame 9 and 10, respectively, so that the viscous during its formation, doughy weld seam 25 is, after less than 1 s is exposed, and can cool down / cool down quickly.

This is supported by a cooling device 26 , which is arranged within the clamping frame 9 or 10 and is connected to a compressed air source, not shown. The cooling device 26 will now be described in detail below.

It has nozzles 27 through which the transverse weld seam 25 can be blown on its two outer sides in a controlled manner with cooled air (cooling air) as soon as the welding strips 7 , 8 have moved away from it.

Before further comment is made on the cooling device 26 further below, reference should be made to the following with regard to the further procedure: as soon as the cross-weld seam 25 has cooled to such an extent that it has solidified again, the tube section provided with the cross-weld seam 25 is attached to one between the upper clamping device 11 , 13 and the welding device 7 , 8 , a separating line 28 is separated from the hose supply 2 "by a cutting device designated 29 as a whole. For this purpose, the cutting device 29 has a knife 30 which, when the device 1 is opened and closed, outside the Hose area is arranged, and by means of a drive, not shown in detail, is movable along a knife guide 31. The drive can be, for example, a chain drive, the chain 32 of which is indicated by a dash-dotted line in Fig. 8 Knife 30 in its inner position and tre nnt thereby adjacent to form a cover 2 'to provided with a transverse weld 25 the lower tubular section to the cross weld seam 25 a short distance above the weld seam of the tube stock 2 "from.

After opening the device, the film hood formed in this way can be further processed by the packaging machine and pulled over the packaged piece of goods to be wrapped, while from the hose supply 2 "a hose section has already been unrolled in a controlled manner and is guided downwards by the device 1 so that it has the desired hood length after welding.

As can be seen from FIGS. 1-3, the device shown there differs in several ways from the device according to FIG. only the features mentioned Figs. 7, 8 (esp. Fig. 7), iw below, which are for the present invention of particular interest thereof.

Both in the design according to FIGS. 1-3, as well as the variant gem. FIGS. 4-6, the cooling device 26, two on either side of the film tube 2 below the welding means 7, 8 are arranged, hollow air bars 38 which are fed from a compressed air source, the compressed air before reaching the (cooling) air strips 38 temperature nor Raumtem is to be cooled to the respectively adjustable cooling temperature. The air or (more generally) gas strips 38 are provided with nozzles 27 , which are directed obliquely toward the center toward the parallel wall sections 5 of the hose 2 , the direction of flow of the hose 2 being preferably adjustable in that the nozzles 27 are in turn adjustable relative to the respective air or gas strip 38 .

Furthermore, a suction device, designated as a whole by 33, is provided, by means of which cooling air heated during the welding process can be extracted from the device. It has been shown that the cooling of the tube area provided with the transverse weld seam 25 can be accelerated significantly as a result, so that the cooling time and thus the entire cycle time can be shortened significantly.

In the embodiment according to. FIGS. 1-3, the suction hose either side of the path in each case at least one suction nozzle or a suction opening 34 which is connected to a suction blower via a flexible suction 35th This flexibility is necessary because the clamping frames 9 , 10 are moved (horizontally) relative to each other during each cycle.

Are in the initial state shown in Figure 1, both the terminal strips. 11 - 14 and the welding strips 7, 8 (horizontal) in its rest position at a distance from the film tube 2. The welding elements 7 'and 8 ' of the welding strips 7 and 8 are already preheated to the welding temperature of 140 ° C. in the present case. For a line of the hood forming process, the two clamping frames 9, 10 are each moved to the center / from the film tube 2, till the clamping surfaces 15 of the clamping strips 11-14 and the welding strips 7, 8 in pairs to pinch the film tube 2 by means of the two upper terminal strips 11 , 13 above the cutting device 29 , by means of the lower clamping bars 12 , 14 below the welding device 7 , 8 (namely in the area of the cooling device 26 , and in between through the two welding bars 7 , 8 of the welding device. The laying of the cross weld seam lasts not least due to the already preheated welding bars less than 1 s.

As well as afterwards the re-opening of the welding strips 7 , 8 depended on their welding point. Fig. 2 is initiated, the cooling device 26 is activated, which is symbolized by abwech nately black and white designed quadrant in FIGS. 2 and 3 so that the pre-cooled cooling air to the portion of tubing provided with the welding seam 25 even during the process of welding bars 7 , 8 acted upon in their rest position and cools spontaneously, especially since the signal for the spreading of the welding bars 7 , 8 also actuates the suction fan of the suction device 33 , by means of which heated air is sucked out immediately without delay by the welding process or the transverse weld seam 25 and its adjacent film sections ,

This mode of operation is also maintained for a short time when the welding beams 7 , 8 have reached their rest position ( FIG. 3), but the film section provided with the transverse weld seam 25 is immediately after sufficient cooling and the associated consolidation by the knife 30 of the cutting device 29 separated to form a film hood 2 'which, due to the rapid cooling and the strength achieved thereby / thus very quickly, both the transverse weld seam 25 itself and the film areas adjacent to it (which are to a certain extent also heated during the weld seam formation) can be. The hood 2 ', which has already been added to four free reef and stretch elements in the manner of fingers or brackets at its free lower end, therefore no longer requires a (clamped) holder, so that the device also with respect to the clamping frame 9 and 10 , which in their condition according to may be closed to FIGS. 2 and 3 towards iw outward, again according to the initial base position. Fig. 1 can be moved.

The variant acc. FIGS. 4-6 requires a technically somewhat larger effort than the design gem. FIGS. 1-3, this has the advantage over visible but some advantages. With regard to the present invention, it differs from the configuration according to FIGS. 1-3, however, iw by their suction device 33, which has here over the entire tube width (and beyond) extending suction boxes 36, which are located just above the clamping frame 9, 10 and abge at its the tube 2 opposite end are each connected to a suction fan. This training the suction device 33 clearly has the advantage that it can be designed to be stationary, since it is not firmly connected to the relatively movable clamping frames 9 , 10 . It could be considered a disadvantage that the suction power in this embodiment must be higher in order to achieve the same suction effect and thus the same contribution to the rapid cooling of the film. If necessary, such a design of the suction device 33 can of course also with a suction device 33 acc. the training acc. are combined to FIGS. 1-3, so that may arise within the limited of the clamping frame 9, 10 housing, no hot air traffic jam, on the other hand additionally, the heated air is sucked still flowing in the region of the clamping strips 11-14 upward, which - as can be seen from Fig. 6 - according to this design during the cooling-blowing process already in its initial position. Fig. 4 have been moved.

In a preferred variant it is provided that the air nozzles 27 are dimensioned with respect to their total free cross-sectional or passage area so that they can be acted upon on the pressure side with the full gas pressure of the compressed gas source, in order then to provide the desired air throughput and the desired cooling capacity , For example, the nozzles could be pressurized with 8 bar (or more, e.g. 10-15 bar) on the pressure side, so that due to the strong adiabatic cooling of the gas flow during pressure reduction to ambient pressure, a very low temperature can be achieved, which has a correspondingly strong cooling effect has the consequence. Provided that all device components up to and including the air strips are designed to be pressure-resistant, cooling with very low air temperatures (well below 0 ° C) can be cooled by using a compressed air network that is usually already available and without a separate cooling device. To implement this variant, only a controlled valve would be provided in the course of the gas supply, which blocks the compressed gas used for cooling ver against the full gas pressure or releases a loss-free flow.

LIST OF REFERENCE NUMBERS

1

(Haubenbildungs-) device

2

Gusseted tubing

2

'' Foil hood

2

"Hose supply

3

idler pulley

4

wedge plates

5

parallel wall sections (from

2

)

6

grab

6

'Gussets

7

sealing bar

7

'Welding element (from

7

)

8th

sealing bar

8th

'Welding element (from

8th

)

9

clamping frame

10

clamping frame

11

upper terminal block (from

9

)

12

lower terminal block (from

9

)

13

upper terminal block (from

10

)

14

lower terminal block (from

10

)

15

Clamping surfaces (from

11-14

)

16

Contact areas (of

7

.

8th

)

17

guide piece

18

Linear guide (for

17

)

19

Drive (for

9

.

10

)

20

arrows

21

median longitudinal plane (from

1

)

22

joint

23

Drive (for

7

)

24

Drive (for

8th

)

25

transverse weld

26

cooling device

26

Arrows

27

Nozzles (from

26

)

28

detachment

29

cutter

30

Knife (from

29

)

31

knife guide

32

Chain

33

suction

34

Suction opening (from

33

), (

FIG.

1-3)

35

Suction hose, (

FIG.

1-3)

36

Suction box (

FIG.

4-6)

37

arrows

38

Air strips (from

26

)

Claims (19)

1. Method for producing (film) hoods ( 2 ') from a film tube consisting of plastic film, generally supplied from a reeled hose supply, in particular a gusseted tube ( 2 ), in particular for (further) use in a packaging machine, esp. a stretch hood packaging machine, in which the hose ( 2 ) in each case to form a hood ( 2 ')
is provided with a transverse weld seam ( 25 ) at a distance from its free end;
is provided with the transverse weld seam (25) tube portion adjacent to the transverse weld seam (25) of the tube (2) is separated;
and in which the tube section provided with the cross weld seam ( 25 ) after the formation of the cross weld seam ( 25 ) is preferably cooled on its two opposite outer sides ( 5 , 5 ) by blowing with a gas, preferably air, of which temperature (preferably considerably) is lower than the welding temperature, characterized in that the hose section having the transverse weld seam ( 25 ) is blown with the (cooling) gas only from below. 2. The method according to claim 1, characterized in that the hose section with a directed quasi-laminar (i.e. only partially turbulent) gas flow is struck. 3. The method according to claim 1 or 2, characterized in that with the (cooling) Gas to be acted upon hose section along its transverse extension at several A large number of locations distributed over the hose width with a separate one Gas flow is blown, the main blowing direction of each gas flow is designed so that gas flows adjacent to each other before the Hose section meet at least partially. 4. The method according to one or more of the preceding claims, characterized ge indicates that when the hose section cools it flows off / on rising gas is sucked out of the area surrounding the transverse seam hose section becomes. 5. The method according to claim 4, characterized in that the heated gas little is partially suctioned upwards.   6. The method according to claim 4 or 5, characterized in that the heated gas is at least partially suctioned off laterally. 7. The method according to one or more of the preceding claims, characterized in that the cooling ( 26 ) is activated, and the cross weld ( 25 ) is gebil det and the welding device ( 7 , 8 ) is moved back to its rest position. 8. The method according to one or more of the preceding claims, characterized in that the welding elements ( 7 ', 8 ') of the welding device are preheated at least iw to the welding temperature already in their rest position; and that the cooling device ( 26 ) is deactivated as soon as the hood ( 2 ') is separated from the hose ( 2 ) and / or the welding jaws ( 7 , 8 ) are moved again in the direction of the hose ( 2 ). 9. The method according to one or more of claims 4-8, characterized in that the suction of the heated cooling air from the device ( 1 ) after deactivating the cooling device ( 26 ) when the welding jaws ( 7 , 8 ) move together is still continued. 10. The method according to one or more of the preceding claims, characterized characterized in that the cooling gas for applying the film to a predetermined cooling temperature is pre-cooled. 11. Device for producing (film) hoods from a plastic film, usually from a reeled hose supply, especially a side gusseted hose
a guide device (for example 3 , 4 ) for feeding a hose section from the hose supply in order to form a hood ( 2 ');
a welding device ( 7 , 8 ) with heatable welding elements ( 7 'or 8 ') for forming a transverse welding seam ( 25 ) at the free end section of the hose supply or at a distance from the free hose end;
a cutting device ( 29 ) arranged above and adjacent to the welding device ( 7 , 8 ), by means of which the hose section provided with the transverse weld seam ( 25 ) can be separated from the hose ( 2 ) to form a hood ( 2 ');
a drivable first clamping device ( 11 , 13 ) arranged above the cutting device ( 29 ), by means of which the hose ( 2 ) is to be clamped adjacent to the separating line ( 28 ) over its width;
one below and adjacent to the welding device ( 7 , 8 ) arranged, drivable second clamping device ( 12 , 14 ), by means of which the hose ( 2 ) is to be clamped iw over its width; and
of, for performing the method according to one or more of claims 1-10, as marked with a cooling device (26) by means of which the transverse weld seam (25) de tube portion after the melting off of the transverse weld seam (25) to be cooled by, that the cooling device ( 26 ) has two gas strips ( 38 ) arranged on both sides of the hose ( 2 ) below the welding device ( 7 , 8 ), the nozzles ( 27 ) of which are oblique to the parallel wall sections ( 5 , 5 ) of the hose ( 2 ) towards the center are directed upwards. 12. The device according to claim 11, characterized in that the outflow direction of the nozzles ( 27 ) is adjustable. 13. Device according to claim 11 or 12, characterized by a suction device ( 33 ), by means of which heated cooling gas can be extracted from the device ( 1 ) during the welding process. 14. Device according to claim 13, characterized in that the suction device ( 33 ) on both sides of the hose path each has at least one suction nozzle ( 34 ) which is connected to a suction fan via a flexible suction line ( 35 ) ( Fig. 1-3). 15. The device according to claim 13, characterized in that the suction device ( 33 ) on both sides of the hose path has an iw over (at least) the width of the cunning ches ( 2 ) extending suction box ( 36 ). 16. Device according to one or more of claims 11-15, characterized in that the cooling strips ( 38 ) is preceded by a gas cooler, by means of which the cooling gas is to be cooled to an adjustable temperature. 17. Device according to one or more of the preceding claims 11-16, characterized in that the welding strips ( 7 , 8 ) each have a welding wire. 18. Device according to one or more of claims 11-17, esp. According to claim 17, characterized in that the welding strips ( 7 , 8 ) each on their contact surface ( 16 ) to the film - optionally outside of the welding wire - with a strip Tetrafluoroethylene or the like are occupied. 19. The device according to claim 18, characterized in that the welding strips 7 , 8 are each covered below a contact strip made of tetrafluoroethylene or the like with silicone rubber.