Dual contact system for folding in a concertina-fashion

DOUBLE CONTACT FOLDING SYSTEM

The present invention relates to a device for coating individual articles, preferably palletized, with a hose or sleeve stretch film according to the main paragraph of claim 1, as well as the process thereof according to the main paragraph. claim 14.

Devices of this nature for coating individual articles with respect to their base components are described in European Patent 0 344 815 A1. Typically, these devices are composed of a machine frame in which a lifting frame (in a sense that vertically) is moved up and down. The lifting frame usually has a folding frame that moves in the transverse direction (in a horizontally approaching direction) relative to the lifting frame for stretching the stretch film in the transverse direction, i.e. to be able to expand the film in an elastic way, obtaining the so-called horizontal stretching. This is usually a horizontal or transverse stretch from 10% to well over 50% relative to the measurements of the unstretched stretch film in the transverse direction. The stretching means

71574432 can come in quite different ways. Possibilities range from a very simple finger-like presentation to stronger, often T-shaped stretching media with a vertical axis for receiving stretch film and a horizontal section with a certain degree of inclination. , which forms the round in the corner of the folding frame where the stretch film is located. To stretch a hose or sleeve stretch film, the stretching means is uniformly placed at the lower inner end of the hose or sleeve stretch film. Through the folding organs, the stretch film section, which will later coat the side area of ​​the article to be coated, is then stretched over the folding frame.

In a broad context, the folding organs correspond to the parts of the device through which the stretch film is brought into contact for its stretching and whose actuation allows the application of the forces in a certain way on the stretch film, so that this film, by means of the frictional forces arising from the stretching means, it can be folded into harmonic folds over the folding frame. Usually each folding frame corresponds to a folding member in the form of a motor driven folding roll. The folding member can generally be guided to the respective folding frame so that its folding roll, using the folding frame, can press

ΡΕ1574432 as a buttress on the stretch film by pulling the stretch film on the folding frame by utilizing the frictional forces. In this way the stretch film is placed in the folding frame in the form of harmonic folds.

The stretched film section thus stretched can then be stretched transversely, i.e. in the horizontal direction. In this way, said folds, and especially the harmonic folds, are strongly pressed. Thus, there are several points with two or more layers of tightly pressed stretched film, which in a horizontal view are overlapping thus forming overlapping folds.

Film-to-film friction coefficient is usually less than the film-to-frame friction coefficient. The overlapping folds that are set in motion when removing the stretch film from the folding frame (during the stretching film coating process) ideally tend to separate along the folding frame to eliminate overlap before the overlap fold reaches the top corner of the folding frame. However, it may happen that some individual overlapping folds cannot separate so quickly, jumping unevenly from the folding frame. In this case, the overlapping fold is separated so that the individual film layers are no longer overlapping.

Forma1574432 pressed form, as long as the fold is removed from the folding frame, often leading to very thin stretching of the film and rupture of the film.

In addition, in the case of modern stretching means, film breakage may occur when the overlapping fold only reaches the upper corner area of ​​the stretching side of the respective folding frame, and is separated therein, as the modern stretching means are of so that the highest stresses of the stretch film arise in the upper corner area of ​​the stretch side of the folding frame.

In practice, different solutions have been made known in this regard.

Thus, it is already known that, from a vertical point of view, the stretching means must be sufficiently long and that they must be able to stretch the respective organs through their stretching rollers driven respectively in the center of the folding frame, i.e. far enough away from the upper corner of the folding frame so that underneath the stretching rollers the stretch film is folded harmoniously and above the stretching rollers conditioned by its frictional forces, the stretch film is placed smoothly along a non-short path over the extended area of ​​the folding frame. Greater sizing of folding frame

ΡΕ1574432 of this nature is undesirable as it entails additional construction efforts, especially for a higher overall height of the installation and mainly increases the path to be taken in the vertical direction by the folding frame, i.e. the lifting support structure carried to cable in each packing process. In this sense, work speed is negatively influenced, which is of significant importance.

In addition, other devices have been known in practice, which achieve the desired result in their final effect by the fact that stretching through the folding frame on the respective rollers is in a movement against the end of the stretching process translucently with respect to the upper corner of the frame. folding Such movement results in the result of the stretch film being stretched and smoothed over the respective folding frame, so that in the following transverse stretching the overlapping folds only form at a certain distance from the edge of the folding frame. Such further movement of the drawing rollers against the drawing process represents an additional procedural step during the preparation of the stretch film for its application, which in particular in high performance installations leads to an unsupportable waste of time. In addition, the additional need for translational movement of the drawing rollers leads respectively to an industrial effort, which means costs and represents an additional source of possible breakdowns. Still, neither

ΡΕ1574432 In all cases, this type of straightening can be guaranteed to work.

In addition, in the present state of the art, the main paragraphs of claims 1 and 14 of DE 40 37 105 Cl are suggested as an example, in which the longitudinal sides of the stretch structure provide for pairs of rollers, which as soon as the structure stretchers are in the working position of the stretch film, they act as pairs of tension rollers for stretching the film in its longitudinal direction, wherein during the stretching process of the stretch film on the stretching fingers, all rollers work at the same operating speeds and in the same direction of rotation. By stretching the film around the article to be packed the rollers are then driven against its stretching direction, wherein the rollers are driven at different operating speeds in order to ensure a smooth and fault-free stretching of the stretch film.

Accordingly, the present invention aims to provide a device, as well as a process of the above type, which quickly and simply means is able to stretch the film over the stretching means so as to minimize the danger of thereafter from stretching the film the overlapping folds reach the critical area of ​​the folding frame and in these areas the film becomes too thin and susceptible to damage.

The object proposed in this invention is embodied by the use of a device with the features of claim 1, wherein each folding member has folding devices so that the stretchable film acts at least temporarily simultaneously in two zones. spaced in the stretching direction so that the section of the film between the two zones can be arranged without overlapping on the folding frame. For this purpose each folding member has at least one first folding roll and a second pull roll placed laterally in the stretching direction wherein, in the folding operation of the device, the roll in contact with the stretch film It has a slower speed than the draw roll, so that between the folding roll and the draw roll the film is folded without overlapping over the respective folding frame. Any folds in the area between these zones are thus smoothed out during the drawing process.

In this way it is ensured that the stretch film at the beginning of the main proceedings lies in a certain area, not too short (hereinafter referred to as the straightening area) before the upper corner of the folding frame smoothly and thus without overlapping folds. All possible overlapping folds which in the course of application of the stretch film on the article to be packed may arise and follow along the folding frame

ΡΕ1574432 are thus at a defined distance and in the middle of the critical area near the top corner of the respective folding frame, where overlapping folds should not regularly appear in the critical area. In this way, it is ensured that all overlapping folds that do not simply break apart with the application of the stretch film have to travel a certain path along the respective folding frame before reaching the critical area of ​​the respective folding frame. Along the longest route the protruding parts of the overlapping folds undo before the critical area is reached. In this way the risk of damage due to damage to the stretch film is reduced.

These two zones are preferably at a considerable distance so that the overlapping folds can undoubtedly undo, allowing only in rare cases that overlapping folds exist between the zones that can reach the critical area. This effect is achieved both in stretching the film over the folding frame as well as in applying the film.

As already mentioned, the folding members are provided such that each folding member has two folding devices operable in the stretching direction by means of rollers, namely by means of a first folding roll and a second roll. following traction, the distance of which is adjustable.

The device is such that the folding roll, such a roll which acts first at the beginning of the stretching process, rotates at a slower rotational speed within the range that comes in contact with the stretch film than the roll. of the second roll, the next tensile roll so that the stretch film section between the rolls is stretched or flattened without stretching during stretching. Stretching of this nature (without significant film expansion) allows possible folds, which arise in stretching the film in the area between the rollers, to be reliably unfolded.

Preferably, the device is such that the stretch film during the operation of the device does not touch at least one point of an imaginary direct link between said zones and does not come in contact with or as the not even with the folding organs. In this way a very efficient way of smoothing out the folds found during stretching and application in the area between the two rollers is achieved. In this sense, any possible folding in this area can, with this configuration, be easily unfolded, since the friction of each of the film layers is eliminated in the folding area, provided that the respective folding in the direct connection line between said zones. do not come into contact with the medium or the folding member. Thus, the respective force acting vertically on the bend and holding it is eliminated.

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In a preferred embodiment of such a device, during operation of the device, one of the two rollers presses the stretch film against an elastic zone of the respective folding frame. In this way a very effective joint action is guaranteed in the operation of the two rollers, avoiding in all cases an overload of the film in the area between the two rollers. Thus, in the area of ​​the roller that presses against the elastic area, there may be (if necessary) slippage between the film and the roller. Preferably, the elasticity of the elastic area is adjustable to precisely define the moment of onset of the skating.

It is advantageous that at least one of the rollers, preferably the tensile roll, is profiled so as not to come into contact with the stretch film during operation. This effect favors the separation of folds that may arise in the area between the rollers.

If the configuration of the device allows the two rollers of each folding member during operation of the device to be driven by a single motor, then a very small construction effort results. Moreover, it is further advantageous that one of the two rollers, in particular the draw roller, has a neutral point, which allows a free rotation in the direction of stretching to ensure proper unwinding.

Stretch Media Film 1574432. However, it may also be possible to have separate drive motors for the rollers which, by means of individual control, make it possible to increase or decrease the rotational speed to obtain, for example, a braking effect.

The device can be further simplified if, in the case of stretching, only the traction roller is positively driven, i.e. by motor and folding roller, and during negative operation of the device, i.e. It is locked. In this case, a tensile stress is also generated between the two rollers which reliably separates the folds which may arise during drawing in the area between the two rollers.

In addition, it is further possible to provide for an individual and independent motor drive for each of the independent drive rollers and / or regulating organs. Preference is given to a simple and reliable construction solution as described below in the case of the embodiment figures which, under certain conditions, even suit the mounting of other existing installations, as in the device instead of the motor-driven individual stretch rollers a roller tandem can be used which, thanks to a chain mechanism, is also driven by a single motor, therefore no fundamental changes in machine control are required.

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The present invention is of significant importance for packaging machines of this nature, which operate not only with a strong horizontal stretch but also additionally with a vertical height stretch of about 10% to 50%, especially also above 50% of the vertical direction in the undrawn state. In the treatment of stretch films, where they are subjected to a state of high degree of expansion on two axes, the induction of rupture through overlapping folds is to be largely prevented.

The process part of the object of the present invention is embodied in the process described in claim 14, wherein during operation through the folding organs by means of two stretching devices spaced apart from each other act on the stretch film at least simultaneously. in two different zones in the direction of stretching, so that after stretching the stretch film section which lies between the two zones, is arranged without overlapping folds in the respective folding frame. During application, the folds, possibly formed in the area between the two zones, are also unfolded so that they cannot reach the critical area of ​​the upper corner of the folding frame.

The following is an example of an embodiment of the present invention based on drawings. It is illustrated:

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Fig. 1 is a perspective view of a device according to the present invention, namely a folding frame and the corresponding folding member;

Fig. 2 is a side elevational view of the device according to the present invention during stretching of the film over the folding frame prior to transverse stretching, and

Fig. 3 is a side elevational view of the device according to the present invention before removing the horizontally stretched film from the folding frame.

The device according to the present invention is illustrated herein as a whole and is fundamentally composed, according to the above context of the present state of the art, by known base components, which may be in different forms. Other various known components necessary for the complete execution of a packaging process described herein are added depending on each individual case.

Fig. 1 illustrates one of usually four possibly more, about six to eight folding frames 1, as well as the folding member 2 assigned thereto.

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The folding frame 1 is intended to be mounted on a drive system which can move it according to arrow S in the horizontal direction in a reciprocating motion. 0 folding member 2 is comprised of a leading device 4, in this case advantageous with a preferred shape of a pneumatically driven leading cylinder, a folding device consisting of a folding roller 5a and a pulling roller 5b, a folding motor 3 to drive one of the two rollers and for the necessary passage of the chain mechanism 6. 0 feed device 4 may be adjusted and is responsible for positioning the folding roller 5a and the pulling roller 5b in their operating positions and, after a certain time, collecting them from this operating position by a leftward motion or right according to the arrow

V. Normally, the advance device 4 is mounted with its base 7 on the same drive unit which also moves the folding frame 1 according to arrow S in a reciprocating motion. In this way, by simple means, it is ensured that the folding member 2, when separating the folding frame for cross-stretching of the stretch film, is conducted in return with the folding frame 1.

As shown in FIG. 2, the folding frame 1 has a critical area K in the upper corner. This critical area K should be free of or have very few folds in the film upon application, due to the fact that in this critical area K the

ΡΕ1574432 folding present significant changes. As illustrated in fig. 1, for example, the narrow folding frame in the local shrinkage area 9, while thereafter in the upper stretch piece area 10 the film is even widened. If the movie enters area Κ, its effort changes in a very fast sequence. In this sense, overlapping folds should not reach this area, otherwise the effect of this rapid variation of loads increases the danger of making the film too thin or even tearing it. Typically in practical installations this critical area K is in the upper corner area of ​​the folding frame. Alternatively, it is also possible to use approximately smooth folding frames from top to bottom without significant section changes, wherein folding frames of this configuration prevent overlapping folds from jumping out of the folding frame.

At the beginning of each operating process, the folding members are recessed by arrow V so as to form a noticeable gap between the respective folding frame and the rollers 5a and 5b. The folding frame 1 and other (not shown) folding means are somewhat inserted into the stretch film hose opened by additional auxiliary means, preferably being introduced such that the lower corner of the stretch film hose closes a roll 11. free rotation supported on the folding frame 1. Due to the short travel path, the folding frames can

71574432 be positioned on the stretch film hose relatively quickly.

The folding members are then positioned so that the stretch film can be fixed between the free-spinning roll 11 and the folding roll 5a. The folding motor 3 is then connected, whereby the stretch film is pulled down through the contact fixed between the folding roll 5a on the folding frame 1. Shortly thereafter, the lower end of the stretch film hose is also caught by the next pull roller 5b. Thus, it acts on the stretch film in a first contact zone (zone Z1) through folding roll 5a and in a second contact zone (zone Z2) through pull roller 5b. Since in the present embodiment the two rollers are connected by means of a chain mechanism 6 such that the pull roller 5b, placed later, rotates faster than the folding roll 5a, the film, which is between the two rollers 5a and 5b, it is firmly pulled between the contact zones (Z1 and Z2) and, depending on the difference in rotational speeds of the two rollers 5a and 5b, can even be rotated to a certain scale.

As illustrated in figs. 1 and 2, the traction roller 5b in its operating position does not rest directly on the fixed section of the folding frame 10, but acts much more in conjunction with the stirrup 12, which viewed in the horizontal direction is fixed by a screw 14 and is

ΡΕ1574432 supported by bolt 13 on the snap spring in the horizontal direction so as to press the stirrup 12 against the traction roller 5b. Instead of a preferably free position, the stirrup 12 may also be elastically movable. In this way, the stirrup 12 limits the force that the traction roller 5b can apply to the film. Before the film is overloaded during stretching between the slow-moving folding roller 5a and the faster-driving pull roller 5b, slippage will occur between the film and the pull roller 5b. Preferably, the elasticity with which the stirrup 12 is secured may be adjusted, which is not illustrated.

Especially when drawing stretch films from stretch film hoses, it is not possible to prevent any folds in the film from passing through the folding roll 5a and reaching the area between the two rolls 5a and 5b. In this case, and as a result of the faster driving traction roller 5b exerting traction on the film, the folds are separated in this area between the free-rotating roller 11 and the stirrup 12 because they lose contact with the folding frame. .

Traction roller profile also contributes significantly to the elimination of bends and consequently to the improvement of straightening. This profile is composed of individual elastic reliefs 17, between which there is a certain distance (profile spaces).

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In this way, a rapid loading sequence is exerted on the film between the two rollers 5a and 5b, which optimizes the result.

Due to this configuration of the folding member with at least two rollers 5a and 5b along the vertical axis of the folding frame 1 in the stretching direction, after the stretching process it is ensured that between the critical area K and the area BH illustrated in fig. 2, in which the film 8 is folded in harmonic form, is an area G, in which the film is kept practically smooth. The boundaries of zone G in the stretch and application direction mark zones Z1 and Z2, that is, the zones in which the folding roll 5a presses the film against the free spinning roll 11 and the pull roll 5b presses the film 8 against the stirrup 12, thereby establishing fixed contact with the film.

The vertical extent of area G required for each individual concrete case is easily ascertained by the technician. It depends, in addition to the parameters of the device and the film to be used (coefficient of friction between folding frame and film, between film and film, speed of passage of stretch film over the article to be packed, concrete geometry of the folding frame, degree horizontal or vertical stretching, etc.), the intended reliability, ie the degree of security with which the technician wishes to prevent the overlapping folds from reaching the critical area K. This usually results in an optimum compromise of the compact shape of the folding frame on the one hand and a sufficiently reliable way to prevent overlapping folds from reaching the critical area K on the other hand. Area G is preferably between the critical area K and the area ZH, in which the film 8 is folded in harmonic form. For the adjustment of area G or area ZH, the bracket 12 can be adjusted in height, that is, it can be adjusted in the folding frame 12 in the vertical direction, while additionally or alternatively the distance of rollers 5a and 5b can be adjusted. .

The result described above can also be obtained under certain circumstances in which the traction roller 5b is, for example, movably positioned, and is placed just before the end of the stretching process to act in conjunction with the folding roller. 5th However, the preferred solution is the one illustrated in the figures of the present embodiment example, as in this type of configuration the construction effort is kept lower and the danger of error is also reduced as the subsequent placement of the roller Traction 5b in certain circumstances may lead to film clogging or similar consequences.

In addition, rollers 5a and 5b need not be exactly on top of one another. Certain lateral offset is allowed, provided it does not affect its operation, between the two rollers 5a and 5b.

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As illustrated in fig. 3, the loose film in the folding frame is stretched as a function of the required width of the article to be packed by driving the folding frame as well as the folding organs essentially in the horizontal direction. The tensile force obtained by stretching in the horizontal direction of the film allows the overlapping folds 18 of the previously existing loose film to be adjusted in the ZH area of ​​the folding frame.

By vertically moving the complete device during the process of applying the stretch film onto the article to be packed as previously described and illustrated in FIG. 1, the preferred arrangement of the device ensures that the stretch film is smooth, i.e. without overlapping folds, for the beginning of passage through the upper corner of the folding frame 1. All possible overlapping folds during application of the stretch film to the article to be packed and the passage to the respective folding frame 1 respect the defined large distance from the critical area K near the upper corner of the respective folding frame 1, in which the overlapping folds do not preferably enter the critical area. This ensures that any overlap that is not unfolded as the stretch film unfolds must travel a certain path along the folding frame before it can reach the critical area K of the folding frame 1. Along the way between zones Zl and Z2 most of the

ΡΕ1574432 Overlapping folds are unfolded in area G before reaching critical area K. This way the danger of getting too thin or even tearing is lessened.

During the unwinding process, the traction roller 5b rests in its operating position on the horizontally fixed stirrup 12 to maintain the smoothing effect on area G between zones Z1 and Z2, even during the continuity of the unwinding process. In this sense, the lower traction roller 5b preferably rests during its operation on the stirrup 12, which when viewed horizontally is fixed by the screw 14 and which by a compression spring fixed with the screw 13 is placed elastic in the horizontal direction so as to effect the pressure between the stirrup 12 and the traction roller. As already mentioned, the means may, instead of free positioning, be movably fixed.

With a view in particular to preventing clogging of films in area G between zones Zl and Z2 during film unwinding due to the different operating speeds of the two rollers 5a and 5b, It is advantageous to maintain the positioning or actuation of the traction roller 5b such that during the stretching process it can be driven in the stretching direction by the folding motor 3 in order to ensure the difference between the speeds of the two rollers. 5a and 5b and achieve the desired smoothing effect on the

G.1574432 area G. In this sense, the positioning, that is, the drive, of the traction roller 5b additionally has a neutral point which allows the traction roller 5b to be guided together with the film in the operating direction during the unwinding process. During the unwinding process, both folding roll 5a and tensile roll 5b exhibit similar operating speeds. In this case no special neutral point is necessary since the frictional forces from the traction roller 5b, ie the neutral point, are even desired because they have a certain, even small, braking effect on the film. , which in turn has the desired smoothing effect during the unwinding process. Alternatively, it would also be possible to lock the corresponding drive roller in free rotation either in the two-drive device or in the respective lower-speed drive roller to achieve the same desired effect.