Dual contact system for folding in a concertina-fashion

0001The invention relates to a device for enveloping preferably palletized Cargo with a hose or hood-shaped stretch film according to the preamble of the Claim 1 and a corresponding method.

0002Devices of the generic type are, as far as their basic components, usually performed comparable to that of the European patent application 0 344 815 A1 described apparatus. They generally consist of a machine frame, at which a lifting frame on (in an approximately vertical direction) and is moved from. The lifting frame usually carries the folding frame, which in turn compared with the lifting frame in Transverse direction (ie in an approximately horizontal direction) can be moved to the stretch film to stretch after reefing the stretch film to the folding frame in the transverse direction, ie, to expand elastically, so to create the so-called horizontal stretch. Is a common horizontal and transverse stretch from 10% to well over 50%, based on the unstretched dimensions of stretch film in the transverse direction. The folding frame can be very different be configured. The options here range from a very simple, finger-like design to the intended for a stronger stretching Reffbügeln, which often have a T-like shape by a substantially vertical Shaft for receiving the reefed stretch films and carried thereby, in extending substantially horizontally, running with a specific radius of curvature Section consist, held the corner in question the clamped on the Reffbügeln Film formed around. To a tubular or hood-shaped stretch film aufzureffen, are the folding frame regularly in the inner, lower end of the tubular or dome-shaped Stretch film introduced. Agent Refforganen then the portion of the stretch film, is later to cover the side surfaces of the charge to be packaged, to the folding frame reefed.

0003As Refforgan that part of the device is understood in the local context, is brought to the reefing of the stretch film in contact therewith and by means of its Drive forces applied appropriately to the stretch film, so this while overcoming the frictional forces occurring at the Reffbügeln in concertina-like Fold is reefed on the folding frame. Usually, each folding frame is a Refforgan allocated in the form of a motor-driven folding roller. The Refforgan can normally be brought up to the folding frame in question, that the furling foil under suppressed using the folding frame as an abutment to the stretch film and so taking advantage the frictional forces which stretch film draws on the folding frame, so reefing can. The aufgereffte stretch film is then deposited in said accordion-like folds on from Reffbügeln.

0004The finished aufgereffte section of stretch film is then by corresponding movement the folding frame transversely stretched, so usually stretched in substantially horizontal direction. Here are any wrinkles, and in particular the said accordion-like folds strongly pressed together. This come at various places two or more layers strongly pressed by stretch film to each other - seen in the horizontal direction - successive to lie, so wrinkles develop, which can be described as "Überlappfalten".

0005The coefficient of friction "film against film" is generally less than the friction coefficient "Foil against folding frame". The first peel off the stretch film of the Reffbügeln (during the stretch film pull-down operation) screened border in motion and on the Reffbügeln sliding along Überlappfalten therefore ideally have a tendency to the extent to pull apart in the course of sliding along the folding frame that overlap is canceled before the Überlappfalte the upper edge of the respective folding frame reached. However, it often happens that individual Überlappfalten located Do not pull fast enough, but not smoothed jump off the folding frame. In this case, there is a lashing pulling the Überlappfalte whose individual film layers are no longer pressed against each other by friction once the Fold was withdrawn from the folding frame. This often leads to thin drawing the stretch film and thus to tear.

0006It may also in modern Reffbügeln already then a tearing of the film come when a Überlappfalte of only the area of ​​the discharge-sided top reached its folding frame and is pulled apart until there. Because modern Folding frame are designed so that the maximum load of the stretch film hood in the area the withdrawal side top of the folding frame occurs.

0007In practice, various solutions have already been disclosed to the justice to become.

0008So is already known, the folding frame, seen in vertical direction, sufficiently long run and the reefing bewerkstelligenden on the folding frame Refforgane with their driven reefing rollers are each approximately in the center of the folding frame, or far enough removed to allow the withdrawal side top of the folding frame attack, so below the reefing rollers, the stretch film is deposited reefed concertina-shaped and above the reefing rollers, due to the tensile forces, the stretch film hood over a not lies smoothly to small distance on the extended portion of the folding frame. Such, larger dimensions of the folding frame is undesirable. It leads to additional Construction cost, especially to a larger total amount of investments and increased ago all the way, the vertical direction of the Reffbügeln or they holding lifting frame must be covered with any packaging operation. Thus, the operating speed the device affected, which is of particular importance.

0009Furthermore, devices are in practice has been discovered that the desired result achieve in the end characterized in that the reefing the bewerkstelligenden on the folding frame Reefing rollers at the end of Reffvorganges translationally to withdrawal side top the folding frame can be moved. Such movement has the result that the Stretch film on the respective folding frame drawn regionally smooth or smoothed is such that withdrawal side in the subsequent transverse stretching only at some distance from End of the folding frame form Überlappfalten. Such additional movement the reefing rollers at the end of Aufreffvorgangs provides an additional operation in the preparation of stretch film for coating is, the just for high-performance systems leads to an unacceptable loss of time. In addition, causes additional translational Movement of the reefing rollers a corresponding apparatus expenditure, ie costs and also provides an additional source of potential interference. Otherwise is not ensured under all circumstances that such smoothing succeed.

0010The invention is therefore based on the object to provide an apparatus and a method the generic type to create or vehicle quickly and with simple means in the Location is a the side surfaces enveloping section of stretch film as the folding frame aufzureffen, so that the danger that after the stretching when the film is Überlappfalten get up in critical areas of the folding frame, is substantially reduced and the film in these areas will not thin pulled or damaged.

0011The related to the device part of the object is achieved by that each Refforgan comprising reefing with which it at least temporarily at the same time so act in two spaced apart in Reffrichtung zones on the stretch film can that the section of stretch film located between the two zones without overlap is disposed on the folding frame in question. Possibly in the area between Zones reaching wrinkles are both the reefing and during removal smoothed out in this area.

0012In this way ensures that the stretch film at the beginning of the soundtrack drawing process in a certain, not to short range (hereinafter "smoothening" mention may be made) before the withdrawal side top of the folding frame smoothly, without Überlappfalten is on the Reffbügeln. All Überlappfalten that of possibly over Coating the stretch film on the load to be wrapped by the concertina-shaped reefed held film stock will be deducted and then first the relevant slide along folding frame, do so in a defined, greater distance from critical region near the discharge-sided top of the respective folding frame, wherein Überlappfalten regularly should not penetrate into the critical range. So it is ensures that each Überlappfalte that can not in any case immediately on removal from the accordion-shaped stretch film aufgerefften stock dissolves, until a certain Route must slide on the respective folding frame along before the critical area can reach the respective folding frame. During this sliding over a longer Route dissolves the majority of all Überlappfalten on before the critical area is achieved. The risk of interference by thin pulling or tearing of the stretch film, which is particularly precarious when formed of the stretch films previously stretch film hoods were, is substantially reduced.

0013Preferably, the said two zones are so far apart that the Überlappfalten dissolve reliable. Ie. That only in a few cases Überlappfalten between the zones are available and can enter the critical region. This effect is advantageously as both the reefing the film to the folding frame achieved even when the film is of the same.

0014Preferably, the Refforgane equipped so that each Refforgan drivable two, comprises, based on the Aufreffrichtung successively arranged reefing, preferably of rollers, namely a first folding roller and a second, behind arranged pulling roll are formed, the distance between them advantageously is adjustable.

0015Even if the apparatus is designed so that the two rollers of each Refforgans (While using the device) at its passing with the stretch film into contact circumferential rotate at approximately the same peripheral speed, is achieved relatively good results with very little effort. Preferably, the apparatus is, however, designed so that the folding roller, so that roll on which the film at the beginning of Aufreffvorgangs first meets, at their passing with the stretch film in contact with the circumferential slower peripheral speed than the second, so subsequent draw roller, so that the section of stretch film located between the rollers during Aufreffens is pulled or smoothed or pulled without folds. Such a Drag (without significant Expansion of the film) causes any when reefing the hood in the area guessed between the two rollers folds are pulled apart reliably.

0016Preferably, the device is designed so that the stretch film during operation of the apparatus at least one point on an imaginary direct joining line between said zones neither the Reffbügeln still with Refforganen in touch comes. In this way it is possible especially effective when reefing and pulling fallen into the area between the two rollers smooth wrinkles draw. for any arrived in this area wrinkles pulled apart easily with such design , since the friction of the individual film layers in the area of ​​the folds will be lifted when the relevant fold on the direct connecting line between said zones neither the Reffbügeln still with Refforganen in touch comes. Any force acting perpendicular to the fold and the fold frictionally could hold together, is repealed.

0017Here, a design of the device of the type is especially preferable that in a two roles in the operation of the device the stretch film against a resilient expresses the area of ​​the respective folding frame. In this manner, a particularly ensuring effective interaction between the two roles in their effect and in any Case, an overload of the film in the region between the two rollers avoided. Because in the region of the roller which presses against the elastically resilient region, can (if necessary) Slippage between the film and the role occur. Preferably, the spring force is the resilient range adjustable so that can be tuned exactly when Slippage occurs.

0018It is cheap, at least one of the two rollers, preferably the pulley to profile so, that they are not continuously in a rolling on the stretch film to the stretch film is in contact. This favors the pulling apart of the reefing in the area more advisable between the rollers folds. The same applies to an elastic cross Great Profile.

0019You design the apparatus so that the two rollers of each Refforgans during operation of the device are driven by a single motor, is then obtained a particularly low construction cost. It is also advantageous for one of the two rollers, particularly the pulley with a freewheel, which free rotation in the drawing direction allows to provide, to the unimpeded withdrawal of the film from the Reffbügeln to ensure. However, it is also conceivable that separate drive motors for the rollers are provided by the individual control of an accelerated or delayed allow rotational movement of the rollers in order to achieve a braking effect z. B..

0020Even more, the device can be simplified when the reefing only Pulling roller positive, ie motor, drives and the folding roller when operating the device negative drives, ie brakes. Even then arises between these two roles, a tensile stress, the guess when reefing in the area between the two rollers folds reliably pulls apart.

0021Furthermore, it is conceivable for the roles each have their own, independently operated motor drive and / or independently operable Zustellorgane provide. The advantage is however the hereafter of the figures for the concrete embodiment shown, structurally very simple and reliable pronounced to give solution, which under certain conditions even to be retrofitted is of existing systems, since the on the piston rod of the feed device instead of recent single furling foil only the role Tandem be placed with its engine needs, thanks to the chain or belt transmission also only a single Reffmotor is driven and therefore no fundamental changes in the control makes the machine required.

0022Of particular importance is the invention for packaging machines of the generic Art, the one not only with a strong horizontal stretch, but also with additional, significant vertical stretch in the amount of about 10% to 50%, in particular of over 50%, based on the vertical direction in ungestretchten state, work. Because when processing Stretch films such, highly biaxial stress state are subjected, it is particularly true of crack induction prevent by slide on Überlappfalten.

0023The procedural part of the object is achieved in that the stretch film during Aufreffens by Refforgane respectively by means of two spaced apart Reefing at least temporarily simultaneously in two mutually in Aufreffrichtung spaced apart zones is acting on the stretch film, that after completion of the the Aufreffens between the two zones located section of stretch film without overlap is disposed on the folding frame in question. When pulling off are possibly also smoothed out in the area between the zones reaching wrinkles so that they can not enter the critical region of the upper edge of the folding frame.

0024In the following, an embodiment of the invention with reference to drawings is nearer explained. Show it:<dl tsize="6"><dt>Fig. 1</dt><dd>the essential detail of the apparatus according to the invention, namely a folding frame and its associated Refforgan,</dd><dt>FIG. 2</dt><dd>a side view of the essential section of the invention Device during the Aufreffens the film to the folding frame prior to their Transverse stretching and</dd><dt>Fig. 3</dt><dd>a side view of the essential section of the invention Device before removing the foil from the quergestretchten Reffbügeln.</dd></dl>

0025The inventive apparatus, which is not shown as a whole here, consists in essentially of the initially in connection with the discussion of the prior Technology mentioned known basic components configured in many different ways or can be modified. Many other well-known components, the full Performing a packaging process that at issue here kind required are to come - depending on the individual case - added.

0026FIG. 1 shows a generally four - but occasionally more, about six or eight - Reffbügeln 1, as well as an associated therewith Refforgan 2. The folding frame 1 is to be mounted on a drive determines the departures him along an arrow S in the horizontal direction and forth can. The Refforgan 2 consists of a feeding device 4, here in the preferred Form an advantageously pneumatic feed cylinder, from a folding roller 5a and a tension pulley 5b existing reefing, a two Keywords driving Reffmotors 3 and a caring for the required translation chain or belt transmission 6. The feeding device 4 is controlled in accordance with and ensures that the folding roller 5a and the pulley 5b moved forward in its working position and in due course may be retracted from its working position, respectively by a movement to the left or right along an arrow V. The feed device 4 is usually mounted on the same drive unit with its base 7, the also the folding frame 1 along the arrow S reciprocated. is In this way ensured by simple means that the Refforgan 2 at a moving apart Folding frame for the purpose of Querstretchens of stretch film together with the folding frame 1 is returned.

0027As can be seen with reference to FIG. 2, the folding frame 1 at its discharge-sided Top a critical region K. In this critical area K should peel off the stretch film by a reefed held Stretch film supply 8 only a few, preferably almost no Überlappfalten reach. This is because in the critical range K the strap section greatly changes. As shown in FIG. 1, tapers, for example, the folding frame in the region of the constriction 9 locally while in the field below the upper arm part 10, the film then even aufdehnt even stronger. Glides the film this So area along K, so changes its load in rapid succession. Due to this, should Überlappfalten possible not reach in this area, otherwise they under the influence of this rapid load change, the risk of film thin or drawing - , rip increase. The critical region K is the conventional practice used in the Plants in the top of the folding frame. Alternatively, however, is the use of of up and down nearly smooth Reffbügeln without significant changes in cross section conceivable, in this way designed Reffbügeln it then To prevent only applies that Überlappfalten "jump" from the Reffbügeln.

0028At the beginning of each Aufreffvorganges the Refforgane along arrow V are returned, so that an appreciable gap between the respective folding frame 1 and the rollers 5a and 5b consists. The folding frame 1 and the other (not shown) are a folding frame short distance into the most open through additional tools stretch film hose introduced, preferably about so far that the lower edge of the stretch film tube one held on the folding frame 1, idler wheel 11 just covered. on the basis of the relatively short paths required the folding frame is therefore quite fast in the stretch film hose position.

0029Then the Refforgane be delivered, so that the stretch film between the free-running Roll 11 and the folding roller 5a is held by friction. Then, the Reffmotor 3 started, whereupon the stretch film by the frictional contact with the folding roller 5a is drawn to the folding frame 1 downward. A short time later, the lower end of the Stretch film tube frictionally also covered by the downstream drawing roller 5b. On the stretch film so now acts via a first contact zone (zone Z1) the folding roller 5a and via a second contact zone (zone Z2) the pulley 5b. Because the two roles together connecting chain or belt transmission 6 designed in this embodiment as is that the draw roller downstream 5b rotates faster than the folding roller 5a, the Film that is located between the two rollers 5a and 5b, in the region between the Contact zones (Z1 and Z2) pulled tight and depending on difference in rotational speeds the two rollers 5a and 5b even temporarily certain by an amount stretched.

0030As shown by the Figs. 1 and 2, the lower tension pulley 5b is supported in its operative position advantageously not directly on a substantially rigid portion of the folding frame 10 from, but rather acts together with a bracket 12, which in the horizontal direction seen attached by a screw 14 and held by a means of a screw 13 Compression spring in the horizontal direction is spring-loaded so far, that a contact pressure of the Strap 12 is realized on the pulley. Instead of such, preferably floating Storage, the bracket 12 be resiliently-mounted. It limited the Ironing 12 the power that can muster the pulley 5b on the film. This will also the frictional forces limited, it can raise the pulley 5b on the film. Before it overloading of the film during reefing between the slower moving furling foil 5a and the faster current draw roller comes 5b, that will slip between the film and the tension pulley 5b occur. Advantageously, the spring force, held with the support 12 is adjustable, which is not shown here.

0031Especially when reefing of formed of stretch film stretch film hoods hoses it can not be avoided that occasionally foil folds the folding roller 5a while passing the Aufreffens and enter the area between the two rollers 5a and 5b. There they are, due to the fact they have downstream by the rapid current Pulling roller 5b, a train is applied to the film, and these wrinkles in the area between the free roller 11 and the bracket 12 to contact with the folding frame lose, effectively pulled apart.

0032A useful contribution to the elimination of wrinkles and to improve the smoothing makes 5b the profile of the pulley. This profile consists of individual, circumferentially elastic lugs 17 between which each wide spacings are (profile gaps). In this manner, a rapid sequence in rising and falling tensile applied to the located between the two rollers 5a and 5b film the result optimized.

0033Due to this configuration of the Refforgans with at least two, along the vertical axis the folding frame 1, ie in Aufreffrichtung successively arranged rollers 5a and 5b is ensured at the conclusion of reefing that between the critical region K and a range shown in FIG. 2 ZH, in which the film supply 8 concertina-like is reefed, a not only insignificantly far extending portion G is, in the the stretch film is kept practically smooth. The limits of the range G in Aufreff- and Withdrawal direction mark the zones Z1 and Z2, that is, the zones in which the folding roller 5a the film against the idler wheel 11, and the pulley 5b the film against the bracket 12 press and so come into frictional contact with the film.

0034The concrete needed in a particular case vertical extent of the region G, the expert can each easily determined. It depends not only on the to of the device and of the used foils predefined parameters (friction coefficient between folding frame and film, between the film and foil coating speed of stretch film about the Charge, concrete geometry of the folding frame, amount of horizontal and possibly vertical Stretchs, etc.) of the desired reliability, that is, upon the degree of security, with the expert wants to prevent Überlappfalten in the critical area K reach. Normally, an optimum compromise between the required results Compactness of the folding frame on the one hand and a sufficiently reliable avoid Überlappfalten in the critical area K on the other hand. Preferably, the area G between the critical area K and the area ZH, in which the film supply 8 is reefed concertina-like. To set the range G and the range of ZH, , the bracket 12 in its vertical position, ie in the vertical direction, set the folding frame be kept 1 while additionally / or alternatively, the distance between the rollers 5a, 5b adjustable can be.

0035The result described above can also be achieved under certain circumstances be that the pulley 5b is stored, for example, pivotally and shortly before is delivered conclusion of Reffvorganges separately that it cooperates with the folding roller 5a. However, the preferred solution is designed so as in the preferred shown embodiment illustrative figures. For such a design the structural complexity is kept low and also reduces the risk of error, which as this results in that it unfavorable by subsequently delivering the traction roller 5b under Circumstances may lead to an undesirable film jam or the like.

0036The rollers 5a and 5b have also seen in Aufreffrichtung not absolutely accurate to one another lie. A certain, the function is not substantially interfering lateral offset between the two rollers 5a and 5b is permitted.

0037As further shown with reference to FIG. 3, after the reefing on the Reffbügeln located, easy deposited film initially resulted in an in to the required width Dependence of carried goods to be packed apart driving the folding frame and Refforgane stretched in a substantially horizontal direction. The by the moving apart resulting tension of the essential now in the horizontal direction Time Stretch film has the effect that the in the range of ZH during Aufreffvorganges loosely stored stretch film supply 8 superposed Überlappfalten 18 snugly under considerable tension in the region ZH to the folding frame.

0038During the by vertical movement of the entire device during the pull-down operation the stretch film on the load to be wrapped caused peeling operation of the Reffbügeln is due to the described and shown in Fig. 1 illustrated advantageous Embodiment of the apparatus ensures that the stretch film to the beginning of the enrobing process, smooth in the smoothening before withdrawal side top of the folding frame 1, ie without Überlappfalten is on Reffbügeln. All Überlappfalten, possibly in The course of coating the stretch film about the load to be wrapped by the accordion-shaped reefed held, under considerable tension film supply 8 peeled and then first slide the respective folding frame 1 along, are thus in the defined, greater distance from the critical area K near the withdrawal side upper edge of the respective folding frame 1, wherein Überlappfalten advantageously usually not penetrate into the critical range. It is thus ensured that each Überlappfalte that can not in any case immediately on removal from the concertina-shaped aufgerefften stretch film stock 8 dissolves only a certain distance on the relevant Folding frame must slide along before the critical area K of the respective folding frame can reach. 1 During this sliding over this distance between the zones Z1 and Z2 dissolves the majority of all Überlappfalten in the area G, before the critical area K is achieved. The risk of interference by thin pulling or tearing the stretch film, which is particularly problematic given previously from the stretch film stretch film hoods were formed, is thereby substantially reduced.

0039While pulling the unit to the pulley 5b is supported in its operating position continues on the seen in the horizontal direction floating bow 12 from so the smoothing effect in the area G between the zones Z1 and Z2 also during pulling continue to hold up. Here, the lower tension pulley 5b supported in their Operating position advantageously from on a bracket 12, which in the horizontal direction seen fixed by the screw 14 and held by a means of a screw 13 Pressure spring in the horizontal direction is spring-loaded so far, that a pressure of the strap 12 is realized on the pulley. As already stated, the bracket may take place such, preferably floating storage be resiliently pivoted.

0040To a particular film Jam at G between zones Z1 and Z2 while the peeling of the film due to the diverging peripheral speeds of the two Rollers to avoid 5a and 5b, it is advantageous for the storage and the drive of the make traction roller 5b such that it over during the corresponding Aufreffvorgangs the Reffmotor 3 can be driven in Aufreffrichtung to the difference in the peripheral speeds the two rollers 5a and 5b and thus ensure the desired smoothing in to reach the area G, the storage or the drive of the draw roller 5b but additionally is equipped with a freewheel, which the rotating with the shaft of the tension pulley 5b with the film in allows withdrawal direction during pulling. During the removal process Thus, the folding roller 5a and pulley 5b almost the same peripheral speed on. A particularly low-friction, elaborately designed freewheel is not here necessary because the frictional forces of the traction roller 5b and the freewheel rather desirable are because of this a certain, albeit slight braking effect on the film exerted, which in turn the desired smoothing effect now pulling the unit off leads to. Alternatively, it would also be conceivable, the free-running draw roller according decelerate or those with a body having two drives device to drive the pulley with a lower speed, so that also the desired Effect occurs.