Device for gluing together two webs of packaging material

Described is an apparatus for glueing two webs (3, 4) of packaging material for the production of liquid-tight packs, wherein each web (3, 4) is covered at least at one side with a liquid-tight adhesive layer (58, 65) which can be activated by heat, comprising    In order when changing an empty roll to a new full roll at the factory to provide the material web with a factory adhesive location of adequate quality which ensures a higher and more reliable level of liquid-tight sealing integrity, it is provided in accordance with the invention that the welding unit (30) has a slider (31) which is displaceable along a transverse rail (28) substantially transversely with respect to the direction of travel (9) of the material web (3, 4) and on which are arranged a heating means (33) and therebehind in the direction of displacement (20) a pressure roller (38).

The invention concerns an apparatus for glueing two webs of packaging material for the production of liquid-tight packs, in particular for liquid foods, wherein each web is covered at least at one side with a liquid-tight adhesive layer which can be activated by heat, comprising

clamping means for clamping the material webs fast,

a cutting unit for applying an inclined cut extending substantially transversely with respect to the material web, and

a welding unit for applying heat and pressure for glueing the material webs along an adhesive strip.

Packs for liquid foods, for example juices or milk, are known, comprising plastic-coated paper, cardboard or generally a coated fibre layer. Such packs are produced in known filling machines from individual rolls from which the respective material web is drawn. Such individual rolls comprise a wound material web which is previously embossed, stamped, laminated and so forth. The filling machine continuously produces the liquid packs, with the material web being continuously withdrawn from the individual roll. When the individual roll is exhausted, a reserve roll must be in readiness in good time and the trailing edge of the ‘old’ material web of the exhausted individual roll must be joined to the pre-prepared leading edge of the new individual roll. That method of joining the two material webs is also referred to as ‘splicing’.

In regard to processing individual rolls in filling machines, it is also known that a cut, open edge of the fibre layer, for example the paper layer, leads to swelling and a loss of sealing integrity upon coming into contact with the packaged liquid.

Therefore EP-A-00 118 863.0 already discloses a method of providing one of the two transverse edges of the material webs with an inclined cut and then, with the acutely terminating edge of the material web being bent over, glueing it in such a way that a liquid-tight weld is provided on the product side. In that way the originally open surface of the fibre layer is covered by plastic material and liquid-tightly welded.

In the case of the individual rolls which are processed in filling machines, heat and pressure can be applied simultaneously over the complete width of the material web by clamping a first bar against a second one, so that, in combination with the inclined cut, it is possible to produce liquid-tight packs.

The individual rolls are produced by cutting machines which make it possible to cut the desired number of individual rolls from a large wide master roll, after the laminating, printing, coating and so forth steps.

The problem of the wide material web and thus exhaustion of the first roll is known. It was however hitherto difficult if not impossible for the trailing edge of a wide master roll to be glued to the leading transverse edge of the reserve master roll, for, by virtue of the width of for example 1.6 m of a master roll, it was not possible for pressure and heat to be applied in the correct amount and at the right time to the complete width of the transverse edge of a material web in such a way that it was possible to produce an adhesive join of good quality and with good liquid-tight sealing integrity.

Therefore the object of the present invention is, when changing an empty roll for a new full roll, at the factory, to provide the material web with a factory adhesive location of adequate quality which ensures a higher and more reliable level of liquid-tight sealing integrity, wherein preferably a cut is made in the material web at the same time after producing the adhesive strip.

According to the invention that object is attained in that the welding unit has a slider which is displaceable along a transverse rail substantially transversely with respect to the direction of travel of the material web and on which are arranged a heating means and therebehind in the direction of displacement a pressure roller.

The apparatus according to the invention involves glueing two webs of packaging material, the transverse edges of which are to be connected together in the so-called splicing method, for example welded or spliced. The packaging material is a laminated or composite material. Generally and in a particularly advantageous feature the glueing apparatus according to the invention can be used on a paper material coated at least on one side with plastic material. Liquid-tight packs are produced therefrom in known manner. At least the surface of the packaging material, which faces towards the liquid product, must be provided and covered with a liquid-tight layer. If this is an adhesive layer activatable by heat, such as for example an adhesive substance or a plastic material, for example polyethylene, then an adhesive effect is achieved by virtue of the action of heat and pressure. That adhesive effect is produced in the fashion of a kind of weld. So that the trailing edge of the ‘old’ material web, that is to say the first material web, comes to lie in the correct position relative to the leading, pre-prepared transverse edge of the ‘new’ or second material web, in the correct or decorative position, suitable clamping means must be provided. The transverse edges are held and brought into the correct position relative to each other by the clamping means in order thereafter to cause the welding unit to operate.

If, as in many known methods, a fibre layer or paper layer is cut perpendicularly with respect to the surface of the material web, then in most cases the plastic coating is not sufficient, even in the case of a composite material, in order to allow a sufficient amount of plastic material to flow out under the effect of heat, to close the open cut edge. Therefore, the inclined cut which has already been described in the opening part of this specification was produced, the face of which includes an angle of 10 to 40°, preferably 20°, relative to the surface of the material web.

It is now possible for the first time by virtue of the invention to provide an apparatus with which it is possible by welding to produce an adhesive strip, even when dealing with relatively wide material webs, that is to say a so-called factory adhesive location, in which respect it is assumed that the master roll which is processed at the factory is of a width of for example 1.6 m. In accordance with the invention there is provided a slider which is displaceable substantially transversely with respect to the direction of travel of the material web, and disposed on that slider is a heating means and a pressure roller. Therefore, when producing the factory adhesive location, the through movement of the material web is stopped for a short time and the slider is moved substantially transversely with respect to the direction of travel of the material web from one longitudinal edge thereof to the other, in such a way that the heating means produces heat activation of the packaging material at the correct location over the entire width of the web and immediately thereafter the pressure roller provides that the transverse edges of the packaging material, which are to be closed, are pressed against each other. It is then possible in that way to produce a factory adhesive location, even when dealing with a wide material web. The quality of that adhesive location is excellent and guarantees reliable liquid-tight sealing integrity.

If, in a further advantageous configuration of the invention, a cutting blade is arranged on the slider on the side opposite to the pressure roller with respect to the heating means, it is possible to produce a cut in the material web at the same time after production of the adhesive strip. By virtue thereof, it is possible for example to cut off the non-glued overlapping end region, beside the adhesive strip. In that way for example when dealing with the new material web which is drawn off the full new master roll, it is possible for the preparatory cut to be produced as desired only once by hand because the operation of exactly cutting it off is effected immediately after the welding operation by the cutting blade. That is preferably a rotating cutting blade. It can be mounted rotatably on the displaceable slider in a simple and precise manner and provides for precise guidance of the cut in relation to the adhesive strip.

It is particularly desirable in that respect if, in accordance with the invention, arranged beside the pressure roller on the slider is a guide element for lifting the material web along the transverse edge thereof during the displacement of the slider. The guide element acts like a wedge and lifts the material web to be glued by some millimeters in such a way that the heating means can apply the heat necessary for softening the plastic material and for welding it precisely to the regions of the later adhesive strip. While the guide element lifts the material web somewhat at its transverse edge to be glued, the pressure roller, after application of the heat, presses the two material webs together so that the desired adhesive strip can be produced.

The heat can be applied in a particularly simple manner if, in accordance with the invention, the heating means has a hot air element, a transfer tube and a hot air nozzle, preferably in the form of a wide-slot nozzle. The hot air element which is available on the market can produce hot air and blow it in a blower-like fashion into the above-mentioned transfer tube which supplies the hot air nozzle with the hot air in such a way that a jet of hot air issues from the nozzle and can impinge on the surfaces, which are appropriately arranged, of the material webs.

It is also desirable according to the invention if the welding unit and the transverse rail can be raised and lowered in the lifting direction substantially perpendicularly to the direction of travel of the material web and the direction of displacement of the slider. Taking the direction of travel of the material webs as a datum, then the transverse rail extends and the welding unit is displaced substantially perpendicularly with respect to that direction of travel, in which respect deviations of up to 30% are possible. The terms ‘perpendicular’ and ‘transverse’ are to be interpreted in that sense. In a direction of viewing perpendicularly on to a material web which is guided straight, it can be easily imagined that it extends for example from above downwardly (direction of travel) so that the transverse rail consequently extends transversely with respect thereto from right to left or vice-versa and the welding unit is displaceable by way of the slider in parallel relationship with the transverse rail, that is to say substantially transversely with respect to the direction of travel of the material web. The welding unit with the transverse rail can now also be raised and lowered in the third direction perpendicularly to the two directions just described above. In the example just considered the lifting direction would be in the direction of view, or in opposite relationship thereto.

The advantage of this structure is that the material webs can be prepared and positioned correctly relative to each other in their welding position or decorative position, and it is only thereafter that the welding unit is set in operation. The term welding is used here to denote heating and pressing together, so that the softened plastic material is intimately mixed by the pressure so that a welding effect is produced. After positioning of the material webs the welding unit can then be moved downwardly and set at the correct position so that the heat actually goes to the correct, desired locations for the adhesive strip. Equally the welding unit, after production of the adhesive strip, can be raised out of the operative position again and returned to the initial or zero position.

If, in a further advantageous configuration of the invention, fixed below the transverse rail is a first clamping bar and at a spacing therebeneath a second clamping bar the lifting movement of the welding unit with the transverse rail can also be used at the same time to clamp fast the previously positioned material web and only then to form the adhesive strip. In the lifted condition the welding unit is further away from the material web than in the lowered condition. Then, the spacing between the first clamping bar and the second clamping bar arranged therebeneath is at the greatest. When the welding unit has been lowered then that spacing is reduced, the spacing at the minimum being so small that only the thickness of the material web has space therebetween. In the minimum case that spacing is then therefore equal to the thickness of the material web.

It is further advantageous in accordance with the invention if the pressure, when producing the adhesive strip, is produced by the pressure roller and a rubber pressure member mounted opposite thereto, wherein the rubber pressure member is in the form of a bar which extends parallel to the transverse rail and which has roof-like inclined surfaces. The pressure roller can be produced from material of varying hardness. It has however proven to be advantageous for the pressure roller to be caused to operate against a rubber pressure member because that provides for best compensation for very small unevenness in the material web, by virtue of tolerances. Nonetheless the rubber pressure member must be of adequate hardness that its external profile with the inclined surfaces is also not substantially altered in operation. A particularly preferred Shore hardness is 86°. If the cross-sectional area of the rubber pressure member which is of an elongate configuration is considered then the outermost contact edge of the two inclined surfaces is eccentric in such a way that the one inclined surface is smaller than the other.

In a preferred embodiment of a rubber pressure member of a width of about 12 mm, in a projection the width of the one inclined surface is for example 10 mm and that of the other inclined surface is only 2 mm.

The arrangement of the pressure roller on the one hand and the rubber pressure member on the other hand is so selected that, according to the invention, the contact line of the pressure roller against the rubber pressure member is on an inclined surface. While earlier it has in part been thought that the best pressure effect is achieved when the pressure roller comes to apply pressure to the highest line, that is to say the contact line of the two inclined surfaces, in accordance with the invention different factors were found to be better. In a particularly preferred embodiment it was found that the outermost edge of the material web which is cut at an inclination should be arranged and held at a spacing of about 2 mm from the contact line of the two inclined surfaces in order to achieve the best adhesive strip. Therefore the action of the pressure roller has been displaced from the highest location, the contact line of the two inclined surfaces, outwardly in a direction towards the larger inclined surface. By virtue of the new glueing apparatus according to the invention, not only is it possible to provide a clean cut, but in addition there are no longer any problems with the plastic material, for example the polyethylene, at the material edges. In addition it is extremely practical if the pressure required for producing the adhesive strip can be produced by a comparatively small pressure roller which can be fixed to the slider. Preferably the material of the pressure roller is Teflon.

It is further advantageous if in accordance with the invention the clamping means for clamping the material webs fast have a front, a central and a rear clamping device, arranged in the direction of travel of the material web. In that way it is possible for the transverse edge of the one material web to be positioned exactly in relation to that of the other material web and for the various working steps to be carried out precisely and at the correct time.

In the production of liquid packs, problems already always occurred if a weld seam had to be applied over a different number of material webs. Thus it is possible easily to envisage a mutually superposed longitudinal weld seam. If that longitudinal weld seam is to be crossed by a transverse weld seam, then there are four layers of material at the location where the two weld seams cross, whereas therebeside there are only two material layers. That differing number of web layers at the individual locations resulted in leaks. In order in accordance with the invention also to provide measures in the production of the adhesive strip, the new glueing apparatus is further characterised in that the transverse rail of the welding unit and the clamping bars and clamping beams of the welding unit, which extend parallel to the transverse rail, are set at an angle (α) relative to the direction of travel of the material webs of 60° to 100°, preferably 70° to 90° and particularly preferably 85°. If the adhesive line is produced with an apparatus having those features, it extends at the above-mentioned angle α relative to the direction of travel of the material webs. The non-expert observer could think that the above-mentioned transverse rail and the elongate clamping means are set at an angle of 90° relative to the direction of travel of the material webs. Then, the desired adhesive strip between the two material webs would also be at 90° relative to the direction of travel thereof. By virtue of the measures according to the invention however the new adhesive strip extends set at an angle α relative to the direction of travel. In this case consideration is given to that angle α which, in the direction of view perpendicularly on to the material web which extends straight, is for example to the left of the direction of travel. When viewing the situation in that way the transverse rail with the other parallel parts extends slightly from top left towards bottom right, for which reason the angle α at the left is less than 90°. An adhesive line which extends inclinedly in that way considerably facilitates the production of a pack, namely if longitudinal seams cross that new adhesive strip. In addition a pack produced in that way enjoys substantially better strength. An adhesive strip produced in that way is stronger. The material with such an adhesive strip slips better over the various guide locations, for example constrictions in the product-guiding region, such as for example the pressure flange on the filling tube.

The above-mentioned cutting unit which is intended to produce the inclined cut along the transverse edge of the material web then extends at the above-mentioned angle α. The cutting unit can also carry a blade which is fixed on a carriage which is drawn to and fro over the width of the material web when it is stationary. In that way the inclined cut can be very precisely applied at exactly the correct position of the material web, even if the latter, as drawn from a master roll, is of a considerable width of for example 1.6 m.

Because the new adhesive strip can be extremely strongly produced with the glueing apparatus according to the invention, it is possible to produce aseptic packs without having to have considerations in regard to leaks.

As shown inFIGS. 1 to 3, fixed on an elongate carrier plate1which extends substantially over the entire width of the refining machine and thus also over the width of the material webs3and4is a base plate2of almost equal length, on which is fixed a clamping device with respective mutually spaced cylinders6for pressing against the clamping device5. InFIG. 3the clamping device5is enclosed by a dash-dotted line. Here, this involves a so-called central clamping device5which by way of a clamping cylinder6can lift a clamping bar7upwardly in the lifting direction8away from the base plate2or move it theretowards. The lifting direction8is illustrated inFIG. 3by the white double-headed arrow at the right. That direction is perpendicular to the material webs3and4which are transported flat at the height of the surface of the base plate2in the direction of travel9. InFIG. 2the lifting direction8would be the viewing direction or in opposite relationship to the view. The dash-dotted line10inFIGS. 1 and 2is the longitudinal centre line through the material webs3and4, which is also parallel to the direction of travel9thereof.

Arranged downstream of the clamping device5in the direction of travel (and laterally displaced, as can be seen fromFIGS. 1 and 2), is a cutting unit11which in the sectional view inFIG. 3is again enclosed by a dash-dotted line. That cutting unit11is movable substantially (somewhat less) over the length of the clamping bar7transversely over the material webs3and4by means of a guide carriage with guide rail, indicated overall by reference12. Mounted on the guide carriage12is a blade holder13from which projects a blade14with two cutting edges. The knob15which is mounted at the top makes it possible to grip the guide carriage with rail12in order to produce an inclined cut16which extends substantially transversely with respect to the material web3or4.

The inclined cut16can also be particularly clearly seen in the diagrammatic representation of the material webs3and4shown inFIGS. 6 and 9. The old, outgoing material web3comes from the right as indicated by the direction of travel9inFIG. 3and moves towards the left (as shown inFIGS. 1 and 2downwardly). Before being joined with the glueing apparatus the trailing transverse edge17of the leading, first ‘old’ material web3firstly receives the inclined cut16before the leading transverse edge18of the new, rear, advancing material web4is laid into the welding or decorative position shown inFIG. 9.

In the illustrated embodiment in particular inFIGS. 6 and 9the angle of the inclined cut16on the one hand and the inner surface19of the front, outgoing material web3on the other hand is about 20° (FIGS. 6 and 9). The inclined cut16extends over the entire width of the material web3and4respectively in a direction20substantially perpendicularly to the direction of travel9or the longitudinal centre line10of the material web. The specified direction20is only ‘substantially’ or approximately transverse with respect to the longitudinal centre line10of the material web3,4because the clamping bar7, like also other means still to be described, in the embodiment illustrated here, do not extend exactly transversely with respect to the longitudinal centre line10, but are set at an angle α which, as shown in the view inFIG. 2, is measured to the left of the longitudinal centre line10and is therefore less than 100°, more specifically in the range of 60° to 100°, preferably 70° to 90°, and is quite particularly preferably 85°.

Further forwardly in the direction of travel9of the material webs3and4, further downwardly in the view inFIGS. 1 and 2and further to the left in the view inFIG. 3, is disposed the clamping and positioning unit21generally identified by reference21. This is again enclosed inFIG. 3by the dash-dotted line. The clamping and positioning unit21includes one of seven items of clamping cylinders24secured to an elongate holding bar22. Disposed at a spacing below the clamping cylinder24, as measured perpendicularly to the plane of the material web3,4, on the holding bar22, there is also a clamping beam23. A guide carriage and guide rail generally identified by reference25also belongs to the clamping and positioning unit21. By means thereof, the holding bar22which extends in the above-described direction20, hereinafter referred to as the direction of displacement20, towards both sides far over the width of the material web3and4respectively, can be displaced in and in opposite relationship to the direction of travel9of the material webs. In the forward movement in opposite relationship to the direction of travel9of the material webs therefore the spacing between the base plate2and the elongate holding bar22is reduced. The drive for that movement is provided by two displacement cylinders26aand26b.The piston rods thereof can be so controlled that the setting angle α of the elongate holding bar22relative to the longitudinal centre line10of the material web remains unchanged. The material web3which lies over the clamping beam23can be clamped fast with the clamping cylinder24. This clamping and positioning unit21is the front clamping device as viewed in the direction of travel9of the material web3,4—in contrast to the central clamping device5.

In addition however upstream thereof, that is to say shown at the right inFIG. 3, there are also rear clamping bars27which thus form the so-called rear clamping device27. The material web passes over the lower clamping bar27thereof and can be clamped fast by virtue of the spacing relative to the upper clamping bar27being reduced by displacement in the lifting direction8. The upper clamping bar27can therefore be displaced downwardly in the direction8on to the lower clamping bar27.

The upper clamping bar27is fixed at the bottom to a transverse rail28. It in turn extends far over both sides of the width of the material web and thus crosses the material webs in practice like the carrier plate7. The transverse rail28is disposed parallel to all the elongate elements such as the carriage plate1, the base plate2, the clamping bar7, the guide rail12, the elongate holding bar22and so forth. If the setting angle α between the elements which transversely extend across the material webs is approximately taken as being about 90°, then the transverse rail28also extends approximately transversely with respect to the direction of travel9of the material webs3and4.

That transverse rail28belongs to a welding unit30which can be clearly seen inFIGS. 1 to 3and as a perspective view inFIG. 4. Once again the parts belonging to the welding unit30are enclosed by the closed, dash-dotted line inFIG. 3(welding unit30).

The glueing apparatus according to the invention involves the production of an adhesive strip which is produced by glueing of the two material webs3and4as shown inFIG. 10in the region of the arrow29by the application of heat and pressure. That adhesive strip29extends over the entire transverse edge17of the outgoing material web3and the leading transverse edge18of the rear advancing material web4. If more specifically the feed roll for the old, leading, outgoing material web3is exhausted or has run empty and the rear, trailing transverse edge17approaches the region of the glueing apparatus in accordance with the direction of travel9, then the machine has to be stopped and the full reserve roll with the new, rear, incoming material4has to be threaded in. Both material webs3and4have to be joined together by the glueing apparatus. That joining or glueing operation is also internationally referred to as ‘splicing’. For that purpose firstly the possibly roughly torn-off respective transverse edge17or18has to be correctly positioned relative to the respective other transverse edge and cut off, in which case thereafter or in the course of the cutting operation the two transverse edges17and18are welded to each other, forming the above-mentioned adhesive strip29. All clamping devices can then be opened and the two webs of material, being the old leading web3and the new trailing web4, can be advanced in the direction of travel9.

The welding unit which is generally identified by reference30also includes the above-mentioned transverse bar28. A slider31is displaceable along the transverse bar28transversely over the material webs3and4and transversely with respect to the direction of travel9thereof, in the above-mentioned direction of displacement20. The slider31includes a support plate32on which are mounted a heating means33with a hot air element34, a transfer tube35and a hot air nozzle36. The temperature of the hot air flowing into the hot air nozzle36in the form of a wide-slot nozzle can be measured by way of the temperature sensor37mounted on the transfer tube35at the top thereof.

The entire welding unit30with slider31and transverse rail28can be raised and lowered in the lifting direction8perpendicularly to the direction of displacement20of the slider31. By virtue of a lowering movement, the spacing between the first clamping bar27fixed under the transverse rail28and the clamping bar27fixed on the carrier plate1beneath same can be reduced to zero.FIG. 3shows that condition in which the upper clamping bar27with transverse rail28and slider31has been moved upwardly in the direction8.

As is particularly clearly shown inFIG. 4, a pressure roller38is rotatably pivoted to the slider31below the support plate32on the side of the hot air nozzle36, in such a way that it can be pressed downwardly in the direction8by way of a pressure cylinder39which is arranged above the pressure roller and which is fixed with four screws to the support plate32. Viewing in the direction of displacement20the pressure roller38is disposed ‘behind’ the hot air nozzle36so that in operation the procedure first involves heating and thereafter applying pressure.

In addition, a circular blade40is pivoted rotatably on the side in opposite relationship to the pressure roller38with respect to the hot air nozzle36, that is to say at left front on the support plate32in the view shown inFIG. 4. The circular blade40can cut off, beside the adhesive strip29, the projecting part of the new rear material web4. Upon the movement of the slider in the direction of displacement20towards front left inFIGS. 1 to 4, firstly the projecting portion is cut off and then the adhesive strip29is produced by heat and pressure.

In addition, mounted beside the circular blade40on the support plate32or the fixing plate portion42thereof is a guide element41which is curved in an approximately quarter-circle configuration. The guide element converges to a point towards the left in the direction of displacement20in such a way that it thickens rearwardly in a wedge shape. In that way the guide element41can lift the overlap of the new trailing material web4so that that overlap is cut off to a previously specified dimension by the rotating circular blade40.

The welding unit30can be moved in the direction of displacement20relative to the transverse rail28by the displacement unit43(not identified in greater detail) in such a way that the circular blade40, assisted by the guide element41, the hot air nozzle36and the pressure roller38can come into operation to produce the adhesive strip29.

To apply the pressure for glueing the material webs3and4along the adhesive strip29the pressure roller38can be moved and pressed by means of the pressure cylinder39against a rubber pressure member50. The rubber pressure member50which is in the form of a bar can be composed of a plurality of elongate portions and can be fixed to the carrier plate1below the pressure roller38over the entire length of the unit1in the manner shown inFIG. 5. The view of the rubber pressure member fixing in the filling machine shows the pressure rail44, having a groove45in which is inserted the fixing anchor (not referenced) of the rubber pressure member50, and is thereafter fixed by applying the upper fixing rail46in recesses provided for that purpose, in the pressure rail44. The rubber pressure member50is secured to prevent it from falling out, by way of the counterpart plate47, by means of screws shown inFIG. 3. When the cross-sectional views of the rubber pressure member inFIGS. 5 to 8are considered, it will be seen that the rubber pressure member50has, towards the open top side which carries the pressure, two roof-like inclined surfaces51and62, namely the large inclined surface51and the small inclined surface52which is set at an angle β of approximately 27° relative thereto. The two surfaces intersect at an upper straight ridge line53against which the pressure roller38would first roll without interposed material webs, without further measures according to the invention. The setting angle γ shown inFIG. 8, also referred to as the contact angle of the rubber member, is preferably about 6°. It is therefore at that angle that the large inclined surface51is set relative to the base plane54of the anchorage base portion of the rubber pressure member50. The setting angle β of approximately 27° is the corresponding angle for the small inclined surface52. In a preferred embodiment the overall width of the rubber pressure member50is 12 mm. Of that dimension, in a projection, when therefore viewing downwardly inFIG. 6, 10 mm is attributed to the large inclined surface and about 2 mm to the small inclined surface52.

The use of the rubber pressure member50with the material webs3and4is shown inFIGS. 6 to 8and is particularly clearly illustrated by the detail on an enlarged scale corresponding to the circle VIII inFIG. 7. That detail is reproduced inFIG. 8. Shown therein is the old, front, outgoing material web3with the inclined cut16at the rear end and the new, rear, incoming material web4laid thereover, without inclined cut. The cut angle δ of the inclined cut16can also be clearly seen once again in the view inFIG. 8. There reference numeral48moreover denotes the decorative side of the packaging material and reference49denotes the product side.

The position of the transverse edges17and18of the material web with respect to the rubber pressure member50and the pressure roller38is important for the quality of the adhesive strip29to be produced. Thus for example in a particularly preferred embodiment it has been found that the rearmost line55at the inclined cut16of the material web3, in the above-described embodiment of the rubber pressure member50and the dimensions thereof, should be about 2 mm spaced from the ridge line53. That spacing d can be clearly seen inFIG. 6. In the preferred and specific embodiment described herein d=2 mm.

FIGS. 9 and 10diagrammatically show the old material web3and the new material web4as are disposed in mutually superposed relationship inFIG. 9in the correct welding and decorative position with their transverse edges17and18and are then welded by the application of heat and pressure, as shown inFIG. 10, in such a way that, in particular at the adhesive strip29, they provide a seal in relation to liquid which is above inFIG. 10so that the material carries the decoration from below. In this preferred embodiment each of the material webs3,4includes a central fibre layer, for example a paper layer56. The respective top side57of the paper layer56is also provided with a polymer layer58, like the top side59of the material web4. This configuration provides on the inner product side an inner surface19in the case of the leading material web3, in the same manner as an inner surface60in the case of the trailing material web4. Applied on the opposite side, that is to say the outer surface61of the fibre layer56, is a further polymer layer62whose outer surface63is liquid-tight outwardly. Also in the case of the other material web4a plastic layer65is applied on the outer surface64so that a liquid-tight surface66is formed. The trailing material web4is provided with a straight cut67without that fibre layer56being covered to prevent the ingress of a liquid.

The above-described apparatus for glueing two material webs3and4operates as follows. The old, front, outgoing material web3moves from right to left in the direction of travel9through the clamping and positioning unit21. When the web is ended, it is stopped with the trailing transverse edge17. A paper loop is drawn downstream of the clamping device21in order to provide for compensation in respect of the later displacement of the trailing transverse edge17. The clamping and positioning unit21will clamp the material web underneath. The web3is clamped fast by the clamping cylinders24and the clamping beam23. Thereafter the material web is clamped fast by the clamping bar7of the clamping device5a,5b.

The material web is cut with the cutting unit11, with the blade14, with the cutting unit11being exactly guided by means of the guide carriage and the guide rail12.

The clamping cylinder24with the elongate holding bar22is displaced towards the right in the view inFIG. 3by the displacement cylinders26a,26bby the clamping and positioning unit, until the web3provided with the inclined cut16has reached the correct position, namely the decoration or welding position. Thereafter the cut material web3is clamped fast in the welding position by the clamping device5by way of the clamping cylinder6and the clamping bar7.

After the new, rear, incoming material web4has been oriented in relation to the old leading material web3, the displacement unit43lowers the upper clamping bar27in the direction8so that the web4is clamped fast between the two clamping bars27.

The two material webs3and4are now welded together by means of the welding unit30. For that purpose the welding unit30is continuously moved in the direction of the arrow20(towards the left inFIG. 4) by means of the displacement unit43. In that situation the guide element41lifts the overlap of the new material web4. The overlap is cut off to a previously specified dimension with the rotating circular blade40. The hot air nozzle36follows the circular blade40between the old web3and the new lifted web4. The plastic layer is heated and caused to melt by means of the hot air nozzle36. The two layers of material are then pressed against the rubber pressure member50with the pressure roller38and thereby welded and glued together.

Thereafter all clamping devices5,27and21can be opened.

The clamping and positioning unit21, like also the welding unit30, are returned to their starting positions.

LIST OF REFERENCES