Deflection roller for web-shaped flat material and method for deflecting web-shaped flat material

Abstract

A deflection roller (1) for web-shaped flat material is disclosed. The deflection roller (1) is designed to discharge an air volume flow that supports the flat material to be deflected, the magnitude of which varies in different regions (5, 6) positioned along the longitudinal extent of the deflection roller (1).

Description

The present invention relates to a turning roll for sheet material and a method for turning sheet material.In the packaging industry, articles are conveyed through a packaging device, wherein in this case a plurality of articles are often packaged with planar packaging material. The flat packaging material can be, in particular, thermoplastic packaging film, wherein a respective blank of thermoplastic packaging film is folded around a plurality of articles in each case and shrunk in a shrink tunnel onto the articles grouped preliminarily for this purpose.In order to be able to form such blanks from thermoplastic packaging film, it is necessary to separate the packaging film, which is initially present in a single web, into at least two webs by means of a cutting and spreading device. The provided wide web of film is thus separated into at least two halves, following which these halves are brought to a sufficient distance to separate blanks from a respective half.At present, the function of film spreading is usually realized by pulling such at least two halves over rigid spreading bodies set at an angle to one another. In order to avoid damage to the halves due to spreading, it is already known to provide the respective spreading bodies with bores from which an air volume flow can flow out.In other technical fields as well, it is frequently necessary for web-shaped flat material to be deflected before it is fed to further processing. For example, labeling machines are to be mentioned for this purpose, in which deflection rollers are provided for a plurality of labels, which are generally provided as web-shaped flat material. Beverage containers made of cellulosic material have also recently existed. In order to be able to form such beverage containers, it is necessary to deflect the cellulose-containing material required for this purpose, which material is also provided as a web-shaped flat material, accordingly.The deflection rollers that have existed up to now for deflecting web-shaped materials have a high energy requirement in order to be able to provide the air volume flow necessary for the contact-free guidance of the web-shaped flat material. Corresponding possibilities would be desirable, with which the energy requirement can be reduced in a simple manner.An object of the invention can thus be seen in reducing the energy requirement during the deflection of web-shaped flat materials and in this case furthermore keeping the risk of the web-shaped flat material being damaged during the deflection low.The above object is achieved with the objects comprising the features in the independent claims.The invention relates to a deflection roller for web-shaped flat material. The deflecting roller is designed for the outflow of an air volume flow supporting the flat material to be deflected, which outflow of air volume flow varies in terms of amount in different regions positioned along the longitudinal extent of the deflecting roller. It may thus be that in certain regions along the longitudinal extension of the deflection roller a small air volume flow is already sufficient in terms of amount in order to avoid a surface contact between the web-shaped flat material and the deflection roller.For a low air volume flow, a low pressure may be sufficient, the generation of which requires only a low energy requirement. In these regions, the deflecting roller can therefore reliably deflect the web-shaped flat material with low energy requirements without the web-shaped flat material unintentionally coming into surface contact with the deflecting roller. In the case of deflection rollers which are known from the prior art, the outflow of the air volume flow takes place homogeneously or substantially homogeneously along the longitudinal direction of the deflection roller, with the result that a correspondingly high air volume flow is provided even in regions in which an air volume flow which flows out in a small amount would be sufficient for the reliable deflection of the web-shaped flat material.Known deflection rollers therefore require a relatively high energy consumption in order to guide the web-shaped flat material free of contact. These disadvantages can be avoided by the deflection roller according to the invention.If, therefore, in the present case a volumetric air flow varying in amount is mentioned, this can be understood to mean such a volumetric air flow which varies with respect to the intensity of the outflow along the longitudinal extent of the deflection roller.The deflecting roller can be designed in such a way that the air volume flow flows out in a first region along the longitudinal extent of the deflecting roller and flows out in a second region along the longitudinal extent of the deflecting roller, wherein the first region and the second region are offset with respect to one another along the longitudinal extent of the deflecting roller.The deflecting roller can be designed such that the air volume flow in the first region flows out of the deflecting roller at a volume per unit time increased by at least 5%, and in particular by at least 10%, in particular more than 25%, compared to the second region, if a substantially identical atmospheric overpressure is applied to the deflecting roller in the first region and in the second region for the outflow of the air volume flow. There can also be a third region in which an air volume flow that is at least 5%, 10% or 25% weaker flows out than in the second region.The first region, the second region and / or the third region can form a substantially identical surface area or different surface areas.In particular, the web-shaped flat material can be packaging film. The packaging film can be formed by a thermoplastic packaging film. Such thermoplastic packaging film is used in packaging technology for shrinking onto groups of articles via a shrink tunnel. After the thermoplastic packaging film has been shrink-fitted onto a respective article group, the individual articles of the respective article group are held together via the thermoplastic packaging film.However, the invention is not limited to such embodiments, so that the web-shaped flat material can also be labels, cellulose-containing material, stretch film, paper and / or further materials or mixtures of the materials already mentioned.If a deflection roller is described in the present context, such a roller can in principle have any shape suitable for deflecting web-shaped flat material. As a rule, a deflection roller will therefore comprise an outer lateral surface which is curved or at least in partial regions extends in an arc shape along its outer circumference, along which outer lateral surface extends in an arc shape the web-shaped flat material is guided or deflected.However, it is not absolutely necessary for the geometry of the deflection roller to be configured exclusively cylindrically, since the lateral surface does not have to run continuously around the longitudinal axis of the deflection roller in a curved or arcuate manner. Thus, it can also be, for example, that the lateral surface of the deflection roller is formed in sections in an arc-shaped or curve-shaped manner and also extends in a straight line in further sections.The deflecting roller can be formed, for example, substantially cylindrically or substantially conically. However, variants are also conceivable in which the deflection roller has an oval cross section.Preferably, at least that region on which the flat material is actually guided is formed convexly or arched in some way.The longitudinal extension extends in a direction which is oriented substantially perpendicular to the conveying direction of the flat material.For the outflow of the air volume flow, the deflection roller can have at least one opening. Embodiments have proven successful in which the deflection roller has a plurality of openings or even a plurality of openings for the outflow of the air volume flow.It is conceivable here for the deflecting roller to form at least one slot or a plurality of slots, from which slot or from which plurality of slots the air volume flow can flow out in such a way that the outflow of air volume flow varies in amount in different regions positioned along the longitudinal extent of the deflecting roller.In this case, it is additionally or alternatively conceivable for the deflecting roller to form at least one bore or a multiplicity of bores, from which bores or from which multiplicity of bores the air volume flow can flow out in such a way that the outflow of air volume flow varies in terms of amount in different regions positioned along the longitudinal extent of the deflecting roller.It is conceivable that the number of bores or slots per area varies or the size of the bores and / or slots.Embodiments have proven successful in practice in which the deflection roller comprises a plurality of pores arranged along the longitudinal extent of the deflection roller for the outflow of the air volume flow. In this case, it may be that a pore density increases or decreases along the longitudinal extent of the deflection roller. Such embodiments make it possible in a simple manner to save energy during the deflection of web-shaped flat material.In particular, it can be that a first pore density is formed in a first region positioned along the longitudinal extension of the deflection roller and a second pore density is formed in a second region positioned along the longitudinal extension of the deflection roller, which is offset with respect to the first region along the longitudinal extension of the deflection roller, which second pore density is enlarged or reduced with respect to the first pore density.If a pore density is described in the present context, this can be understood to mean the ratio of the number of pores to an area size provided via the outer jacket of the deflection roller.Alternatively or additionally, it may be that the deflection roller comprises pores with different pore diameters. In this case, it may be that a plurality of pores having a first pore diameter is arranged in a first region positioned along the longitudinal extent of the deflection roller, and a plurality of pores having a second pore diameter is arranged in a second region positioned along the longitudinal extent of the deflection roller, which is offset with respect to the first region along the longitudinal extent of the deflection roller, which second pore diameter is enlarged or reduced with respect to the first pore diameter.In various embodiments, it is conceivable thata first pore density is formed in a first region positioned along the longitudinal extent of the deflection roller and a second pore density is formed in a second region positioned along the longitudinal extent of the deflection roller, which region is offset with respect to the first region along the longitudinal extent of the deflection roller, which second pore density is enlarged or reduced with respect to the first pore density, and wherein it is additionally provided thata plurality of pores having a first pore diameter is arranged in this first region positioned along the longitudinal extent of the deflection roller, and a plurality of pores having a second pore diameter is arranged in this second region positioned along the longitudinal extent of the deflection roller, which is offset with respect to the first region along the longitudinal extent of the deflection roller, which second pore diameter is enlarged or reduced with respect to the first pore diameter.Embodiments have proven successful in practice in which the deflection roller forms at least two or optionally also at least three chambers offset with respect to one another along its longitudinal extent, which chambers can be acted upon by different pneumatic pressures and to which at least two chambers or optionally also at least three chambers are assigned respective dedicated pores of the deflection roller for the outflow of the air volume flow.By the possible application of different pressures to the chambers, the air volume flow varying in amount along the longitudinal extension of the deflection roller can be set very exactly or preset very exactly. In various embodiments, the deflection roller can therefore have separate pneumatic connections for the at least two chambers offset relative to one another along their longitudinal extent, via which connections the chambers can be supplied with compressed air independently of one another.In various embodiments, it may be that the at least two chambers offset with respect to one another along their longitudinal extent are fluidically completely decoupled from one another. As a result, the pressurization of a first chamber is not influenced by the pressurization of a second chamber. An exact specification of the air volume flow varying in terms of amount can be further improved as a resultAlternatively or additionally, it can be that the deflection roller forms at least two chambers offset relative to each other in the circumferential direction of the deflection roller, which can be supplied with different pneumatic pressures and to which at least two chambers are assigned respective dedicated pores of the deflection roller for the outflow of the air volume flow.It can also be that the deflection roller forms an overpressure region, wherein the first chamber is connected to the overpressure region via a first channel and the second chamber is connected to the overpressure region via a second channel. Such an overpressure region can be supplied with pressure via a single compressed air connection and via a single compressed air generating device. Such embodiments thus make possible a simple fluidic connection of the deflection roller to a single compressed air generating device.The deflecting roller can also comprise an adjusting mechanism, by means of which an opening cross section of the first channel and / or an opening cross section of the second channel can be adjusted. The adjustment mechanism may include at least one axle and at least one slide. The at least one axle can cooperate with the at least one slide in such a way that an opening cross section of the first channel and / or an opening cross section of the second channel can be selectively increased or decreased via a rotating movement of the at least one axle.The at least one axis can form an external hexagon, via which external hexagon the at least one axis can be moved by an operator or in an actuator-driven manner in a rotating manner.It can also be that a proportional valve is assigned to the first channel and / or that a proportional valve is assigned to the second channel. It is also conceivable that a servo valve is assigned to the first channel and / or that a servo valve is assigned to the second channel.It is further conceivable that the plurality of pores is positioned exclusively in a defined surface of the deflection roller, which defined surface narrows along the longitudinal extension of the deflection roller and in this case runs in particular trapezoidally or V-shaped.The invention also relates to a use of a deflection roller according to an exemplary embodiment of the preceding description as an spreader roller for web-shaped flat material. The web-shaped flat material can be a thermoplastic packaging film.The invention also relates to a cutting and spreading device for web-shaped flat material. The cutting and spreading device comprises a separating device for separating the web-shaped flat material into at least two halves and at least one deflecting roller according to at least one exemplary embodiment of the preceding description. The at least one deflecting roller forms at least one spreader roller for the at least two halves.Furthermore, the spreading device comprises a compressed air generating device which is fluidically connected to the at least one deflection roller for the outflow of the air volume flow, so that the outflow of the air volume flow varies in amount in different regions positioned along the longitudinal extent of the deflection roller.The spreading device can comprise a control device and at least one sensor system, wherein the control device is configured via the at least one sensor system for determining a relative distance between the deflection roller and the web-shaped flat material located in the region of the deflection roller. The regulating device is configured and equipped in such a way that it regulates the outflowing air volume flow as required if the determined relative distance deviates from a desired distance stored on the regulating device.The at least one sensor system can be formed by at least one camera.The invention also relates to a packaging system. The packaging system comprises a cutting and spreading device according to an embodiment of the preceding description. It is further provided that the packaging system is designed for separating sheet-like packaging blanks from the at least two spread halves of the web-like flat material and for applying the separated sheet-like packaging blanks to article groups.The invention further relates to a method for deflecting web-shaped flat material via at least one deflecting roller, in particular via at least one deflecting roller, according to an exemplary embodiment of the preceding description. Features which have already been mentioned above with regard to various embodiments of the deflecting roller, the cutting and spreading device and / or the packaging system can also be provided in the subsequent embodiments of the method without being mentioned again.Likewise, the features described below with respect to the embodiments of the method can be provided in the previously already mentioned embodiments of the deflecting roller, the cutting and spreading device and the packaging system without being mentioned again.In the method, in order to support the web-shaped flat material, an air volume flow is discharged from the at least one deflecting roller in such a way that the discharged air volume flow varies in terms of amount along the longitudinal extent of the at least one deflecting roller.Alternatively, the method could be described as follows: Method for deflecting web-shaped flat material via at least one deflecting roller, in which, in order to support the web-shaped flat material from the at least one deflecting roller, an air volume flow varies in terms of amount along a longitudinal extent of the at least one deflecting roller.In particular, the variation can be more than 5%, in particular more than 10%, preferably more than 25%.It can be that the outflowing air volume flow is varied depending on a parameter of the flat material or depending on the production speed, in particular by means of a control and / or a regulation.For example, the parameter may be a tear strength of the material. The parameter can alternatively be determined from an image recording of a finished shrink container.It can be that a relative distance between the at least one deflection roller and the web-shaped flat material located in the region of the at least one deflection roller is determined by sensors and the outflowing air volume flow is adjusted as required by a control system if the determined distance deviates from a predefined desired distance.It is further conceivable that the web-shaped flat material is separated into at least two halves and the at least two halves are spread apart via the at least one deflection roller. For this purpose, a cutting and spreading device according to an exemplary embodiment of the preceding description can be provided.It is also conceivable that planar packaging blanks are separated from the at least two separated and spread apart halves and are applied to groups of articles.A further invention relates to a deflection roller for web-shaped flat material. The deflecting roller comprises at least one replacement part which forms or has a plurality of pores for the outflow of an air volume flow. Furthermore, this deflection roller comprises at least one locking mechanism which is designed for the detachable fixing of the at least one replacement part at a predetermined working position of the deflection roller.In various embodiments, the deflection roller can comprise a plurality of replacement parts each having a plurality of pores for the outflow of the air volume flow. Here, the plurality of replacement parts may be different from each other in terms of the pore diameters of their pores and / or in terms of the pore density. The at least one locking mechanism can be designed for the detachable fixing of the plurality of replacement parts in predetermined working positions of the deflection roller, in which working positions the plurality of replacement parts lie on top of one another with surface contact.Exemplary embodiments are intended to explain the invention and its advantages in more detail below with reference to the appended figures. The size ratios of the individual elements to one another in the figures do not always correspond to the real size ratios, since some shapes are simplified and other shapes are depicted enlarged in relation to other elements for better illustration. FIG. 1 shows a schematic view of an embodiment of two deflection rollers set at an angle to one another. FIG. 2 shows a schematic view of a further embodiment of two deflection rollers set at an angle to one another. FIG. 3 shows a schematic view of a third embodiment of two deflection rollers set at an angle to one another. FIG. 4 shows a schematic view of a fourth embodiment of a deflection roller. FIGS. 5A and 5B show schematic views of a fifth embodiment of a deflection roller according to the invention. FIG. 6 shows a schematic view of an embodiment of a spreading device according to the invention. Fig. 7 shows a schematic view of an embodiment of a packaging system according to the invention. FIG. 8 shows in the flow chart individual steps, as can be provided individually or according to the combination shown in FIG. 8, in various embodiments of the method according to the invention.Identical reference numerals are used for identical or identically acting elements of the invention. Furthermore, for the sake of clarity, only reference numerals are shown in the individual figures, which are required for the description of the respective figure. The illustrated embodiments are merely examples of how the invention may be embodied and do not provide a final limitation.From the prior art, deflection rollers are already known which can guide web-shaped flat material along defined webs. For example, it may be that thermoplastic packaging material must be guided along defined paths in order to be subsequently applied to a respective assemblage of articles and shrunk onto the respective assemblage of articles. The deflecting rollers can be oriented at least approximately horizontally in order to be able to guide the web-shaped flat material along the predefined web.In the prior art, there are also spreading devices which divide web-shaped flat material, which is drawn from a supply roll, into two separate halves and pull the two separate halves apart. For this purpose, the deflecting rollers or the spreader rollers are set at an angle to one another. There are also deflection rollers from further areas, such as the area of labeling technology. In this technical field of technology, deflection rollers may be oriented vertically or at least approximately vertically in order to guide web-shaped flat material comprising labels to a position in which the labels can be applied to articles.Thus, deflection rollers are used in a large number of technical fields in which web-shaped flat material has to be deflected or in which web-shaped flat material has to be moved along a predefined distance. The use of the deflection roller according to the invention is not limited to the aforementioned technical areas. For example, the web-shaped flat material can also have cellulose-containing constituents and can be moved along such deflection rollers.If the respective web-shaped flat material comes into surface contact with a deflection roller during its movement, a static friction is formed between the respective web-shaped flat material and the respective deflection roller. This static friction can initially lead to the web-shaped flat material being unintentionally stretched, which can entail problems during the subsequent further processing. The web-shaped flat material can also be damaged when it makes surface contact with the deflection roller.Therefore, deflection rollers are known which form a low-friction surface in order to be able to minimize static friction between the web-shaped flat material and the deflection roller. Low stiction may often not be sufficient to eliminate the risk of damage to the sheet. Deflection rollers are therefore also known which can emit a volumetric air flow in order to be able to guide the web-shaped flat material without surface contact with the deflection roller and in this case to hold it on a type of air bed. Such deflection rollers require a high energy requirement for the outflow of the air volume flow.By means of the deflection roller according to the invention and the embodiments described below, the energy requirement can be reduced in a simple manner.The sectional view of FIG. 1 shows two such deflecting rollers 1, which are set at an angle to one another and are designed as spreader rollers 3. Two halves were previously formed from web-shaped flat material before being deflected via the spreader rollers 3. Each half is assigned to its own spreader roller 3 and is guided over the respective spreader roller 3.The two halves are not shown in the figures of the present patent application. Each of the deflecting rollers 1 or each of the spreader rollers 3 is closed at their end faces. Via a pneumatic connection likewise formed in the region of a respective end face of the respective spreader roller 3, the deflecting rollers 1 can be connected to a compressed air generating device. The connection leads into a respective overpressure region 17 of the deflection rollers 1.As can be seen from FIG. 1, each of the deflecting rollers 1 or each of the spreader rollers 3 forms a first region 5 having a plurality of first pores 7 and a second region 6 having a plurality of second pores 8. The respective first region 5 and the respective second region 6 are offset with respect to one another along the respective longitudinal extent of the respective deflection roller 1.The pores 8 of the respective second region 6 have an enlarged pore diameter compared to the pores 7 of the respective first region 5. It can also be seen from FIG. 1 that in the respective second region 6 there are exclusively pores 8 with enlarged pore diameter, whereas in the respective first region 5 there are exclusively pores 7 with smaller pore diameter. Due to the different pore diameters, the air volume flow which exits from the deflection roller 1 via the pores 7 and 8 is designed to be different in terms of amount in the respective first region 5 compared to the respective second region 6.In the embodiment variant shown in FIG. 1, a higher proportion of the air volume flow in the second region 6 flows out of the respective deflection roller 1, since the pore diameter is enlarged in the second region 6 compared to the first region 5.When the spreader rollers 3 thus pull apart halves of the web-shaped flat material, the spreader rollers 3 act as levers on the respective half of the web-shaped flat material due to their angular positioning. In the respective second region 6, the leverage is greater than the first region 5, so that a greater proportion of the air volume flow is necessary there in order to be able to avoid a surface contact between the spreading roller 3 and the respective half of the web-shaped flat material. In the first region 5, the leverage of the spreader rollers 3 is smaller, so that there a smaller proportion of the air volume flow is already sufficient to be able to guide the web-shaped flat material at a distance from the respective spreader roller 3.The different pore diameters accordingly result in the air volume flow flowing out of the spreader rollers 3 varying in terms of amount along the longitudinal extent of the spreader roller 3. A larger proportion of the air volume flow in terms of amount flows out of the spreader roller 3 there, where a higher force is required for the spaced-apart guidance of the web-shaped flat material. A smaller proportion of the air volume flow flows out of the spreader roller 3 where a smaller force is already sufficient to avoid contact between the spreader roller 3 and the web-shaped flat material.Since the outflowing air volume flow along the longitudinal extension of the spreader roller 3 is adapted to the leverage effect, a comparatively low atmospheric overpressure in the overpressure region 17 is already sufficient to be able to guide the web-shaped flat material at a distance from the spreader roller 3. A compressed air generating device which pneumatically supplies the overpressure region 17 with compressed air can therefore be operated with comparatively low energy expenditure, since no high pressure differences are necessary between the overpressure region 17 and the atmospheric ambient pressure in order to be able to pull apart the respective webs via the spreader rollers 3 without surface contact.In the exemplary embodiment according to FIG. 1, the spreader rollers 3 form only two regions 5 and 6, which comprise pores 7 and 8 having different pore diameters. In further exemplary embodiments, however, more than two such regions 5 and 6 or, for example, three or four regions can also be formed by a respective spreader roller 3, to which pores having different pore diameters are assigned.FIG. 2 shows a schematic view of a further embodiment of two deflection rollers 1 set at an angle to one another. The deflection rollers 1 from the embodiment according to FIG. 2 are also designed as spreader rollers 3 and pull two webs apart. For this purpose, the spreader rollers 3 are also set at an angle to one another.Almost all pores 7 positioned along the longitudinal extension of the spreader roll 3 have a substantially identical pore diameter. In order to be able to provide an air volume flow varying in terms of amount along the longitudinal extent of the respective spreader roller 3, the spreader rollers 3 are each divided into two different chambers 14 and 16 via a wall 19. The wall 19 is positioned here in such a way that it completely decouples the two chambers 14 and 16 from one another in terms of fluid. As a result, a first pressure level can be formed in a respective first chamber 14 and a second pressure level in a respective second chamber 16, wherein the first pressure level and the second pressure level differ from one another. When webs are pulled apart by the spreader rollers 3, the spreader rollers 3 according to FIG. 2 also act as levers on the respective web, so that a higher pressure level is necessary in the region of the second chamber 16 in order to be able to pull apart the webs without contact with the spreader roller 3.In order to be able to form the respective pressure level in the respective chamber 14 and 16, the chambers 14 and 16 are assigned their own pneumatic compressed air hoses 24 and 26. In embodiments in which the spreader rollers 3 have separate chambers 14 and 16, the compressed air hoses 24 and 26 can also be omitted, so that the respective pressure level can also be introduced directly into the respective chamber 14 or 16 via a compressed air connection assigned to the respective chamber 14 or 16.A compressed air generating device is coupled to the compressed air hoses 24 and 26, which acts upon the chambers 14 and 16 via the compressed air hoses 24 and 26 with atmospheric overpressure and forms a higher pressure level in the second chamber 16 than in the first chamber 14. As a result, an air volume flow is discharged from the deflection roller 1, which varies in amount along the longitudinal extent of the deflection roller 1. In the second region 6, the air volume flow is in each case larger in terms of amount than the first region 5.In the present case, the compressed air hoses 26 are located in sections in the respective chamber 14. The two chambers 14 and 16 are each supplied via their own compressed air hose 24 and 26. The compressed air hoses 24 are connected to the chambers 14. The connections to the chambers 14 and 16, which can be formed, for example, by plug connections and hose clamps and comprise seals for the hose 26 passed through, are not shown.It can be that the compressed air hoses 24 and 26 are connected to a common compressed air generating device or that different compressed air generating devices are assigned to the compressed air hoses 24 and 26. The air volume flow flowing out via the spreader roller 3 can be varied in terms of amount along the longitudinal extent of the spreader roller 3 by the different pressures in the chambers 14 and 16 in such a way that webs can be pulled apart without surface contact with the spreader rollers 3. The energy consumption for the compressed air generating device can be kept very low, since a low atmospheric overpressure can already be sufficient for the respective chamber 14 to be able to guide the web-shaped flat material at a distance from the respective spreader roll 3.As already mentioned above, the pores 7 along the longitudinal extension of the respective spreader roll 3 have a substantially identical pore diameter. However, it can also be the case in embodiments according to FIG. 2 in which the spreader roller 3 comprises a plurality of chambers 14 and 16, that the spreader roller 3 additionally forms a first region 5 and a second region 6, wherein diameters of pores 7 of the first region 5 are formed differently from the diameter of pores 8 of the second region 6.FIG. 3 shows a schematic view of a third embodiment of two deflection rollers 1 set at an angle to one another. Also in the third embodiment according to FIG. 3, the deflection rollers 1 are designed as spreader rollers 3 and pull two halves, not shown in FIG. 3, apart, as has already been described above with respect to the embodiments according to FIGS. 1 and 2. For this purpose, the spreader rollers 3 are also set at an angle to one another.The deflecting rollers 1 or the spreader rollers 3 have pores 7 which have a substantially identical pore diameter along the longitudinal extent of the respective spreader roller 3. In the respective outer region or in the respective second region 6, a higher proportion of the volume of air flowing out has to be provided in terms of amount than the respective first region in order to be able to guide the respective half of the web-shaped flat material without surface contact with the spreader roll 3.As can be seen from FIG. 3, the pores 7 are positioned exclusively along a defined surface 28 of the deflection roller 1, which defined surface 28 narrows in the longitudinal direction of the deflection roller 1. In the region of the defined surface 28, the halves of web-shaped flat material are located when they are moved apart via the spreader rollers 3. In an outer region or in a respective second region 6 of the respective deflection roller 1, the defined surface 28 is enlarged, since here, due to the leverage effect, a greater force is exerted on the respective half of the web-shaped flat material. As the distance from the respective outer region increases or as the distance from the respective second region 6 increases, the defined surface 28 decreases, since the air volume flow required for the spaced-apart guiding of the respective web can decrease increasingly, without the respective half of web-shaped flat material contacting the deflection roller 1 in this case.The embodiment according to FIG. 3 also makes it possible to reduce the energy consumption required for spreading web-shaped materials, since comparatively low atmospheric overpressure must be applied to the deflection rollers 1 or the spreading rollers 3 for this purpose. The compressed air hoses, via which the deflection rollers 1 are supplied with compressed air, are further shown with reference numerals 24 and 26.In the embodiment according to FIG. 3, the deflection rollers 1 have only one overpressure region 17, as is also illustrated by way of example in FIG. 1 with reference to the numeral 17. However, it is also conceivable that the deflection rollers 1 according to the embodiment according to FIG. 2 have a plurality of chambers 14 and 16, respectively, which are possibly separated from one another by a wall 19.As already mentioned above, in the embodiment according to FIG. 3, the pore diameter of all pores 7 positioned along the longitudinal extension of the respective deflection roller 1 is substantially identical. However, it is also conceivable for the embodiment according to FIG. 3 that the diameters of pores 7 vary in different regions positioned along the longitudinal extension of the deflection roller 1, as already shown and described in FIG. 1.FIG. 4 shows a schematic view of a fourth embodiment of a deflection roller 1. It is also possible to provide two deflecting rollers 1 according to FIG. 4, which are set at an angle to one another and are designed here as spreader rollers 3. The deflecting roller 1, as is shown in the exemplary embodiment according to FIG. 4, is oriented at least approximately horizontally when web-shaped flat material is deflected by means of the deflecting roller 1.A housing 45 is a component of the deflection roller 1. Compressed air can be introduced into the overpressure region 17 via the compressed air connection 47, so that atmospheric overpressure prevails in the overpressure region 17. A first channel 41 formed in the housing 45 leads from the overpressure region 17 into a first chamber 14 of the deflection roller 1. In addition, starting from the overpressure region 17, a second channel 42 leads into a second chamber 16 of the deflection roller 1. The first chamber 14 and the second chamber 16 are separated from one another by a seal 23, so that different pressure conditions can be formed in the first chamber 14 and 16.The deflecting roller 1 also comprises an adjusting mechanism 18. In addition, the adjusting mechanism 18 has an axle 24 and two adjusting elements 25, The adjusting elements 25 are positioned outside the housing 45 in the embodiment according to FIG. 4 and each form an internal thread which interacts with a corresponding external thread of the axle 24.In the present case, a respective adjusting element 25 is an external hexagon 27.If the two adjusting elements 25 still tightened in FIG. 4 are now released by a respective rotating movement and in this case move away from the housing 25, the axis 24 can be moved in the axial direction together with the slide 21. As a result, the opening cross sections of the channels 41 and 42 can be selectively enlarged and reduced. When the slide 21 has reached a desired position, the adjusting elements 25 are tightened, coming into contact with the housing 45 under the action of force, and the slide 21 is held immovably in its respective position by the axis 24 in the housing 25.As FIG. 4 shows, the housing 45 forms pores 7 in the region of the chambers 14 and 16, respectively, through which pores an air volume flow can flow out of the chambers 14 and 16. Since the pressure level prevailing in the chambers 14 and 16 is influenced by the opening cross section of the channels 41 and 42, the outflow of the air volume flow along the longitudinal extension of the deflection roller 1 can be varied in terms of amount via the adjusting mechanism 18.The larger the opening cross section of the respective channel 41 or 42 is formed, the greater is the respective atmospheric overpressure which prevails in the chamber 14 or 16 connected to the respective channel 41 or 42. Reference is also made to the different regions which are positioned offset with respect to one another along the longitudinal extent and in which the outflow of air volume flow then varies in terms of amount. The first region 5 is assigned to the first chamber 14, wherein the second region 6 is assigned to the second chamber 16.In order to increase and decrease the opening cross sections of the channels 41 and 42, it may also be that a sealing element is located in each of the channels 41 and 42. The respective sealing element can cooperate with the axle 24 in such a way that, during a rotating movement of the axle 24, the respective opening cross section of the channels 41 or 42 is enlarged or reduced.In embodiments in which the opening cross sections of the channels 41 and 42 are adjusted via the slide 21, it can also be provided that the adjusting elements 25 are seated on the axle 24 in a rotationally fixed manner. The axle 24 can extend through the slide 21, wherein the slide 21 forms an internal thread which interacts with a corresponding external thread of the axle 24. When the shaft 24 is rotated, the slider 21 will either move in the leftward direction depending on the rotational direction, thereby decreasing the opening area of the first passage 41 or move in the rightward direction, thereby decreasing the opening area of the second passage 42.In the embodiment according to FIG. 4, the adjusting elements 25 can be rotated by an operator and by means of a tool. However, an actuator can also be provided which is mechanically linked to the adjusting elements 25 and rotates the adjusting elements 25 as required if the opening cross sections of the channels 41 and 42 are to be enlarged or reduced.Furthermore, it is conceivable for embodiments according to FIG. 4 that the adaptation of the opening cross section takes place with the aid of a proportional valve.FIGS. 5A and 5B show schematic views of a fifth embodiment of a deflection roller 1 according to the invention. Two deflection rollers 1 can also be provided for deflection rollers 1 according to the embodiment according to FIGS. 5A and 5B, which are set at an angle to one another and thereby form spreader rollers 3 corresponding to the previous description relating to FIGS. 1 to 3.As shown in FIG. 5A, the reversing roller 1 comprises three replacement parts 52, 54 and 56. the replacement parts 52, 54 and 56 lie on top of one another in FIG. 5A and are held in their position by a locking mechanism 49. At least one of these replacement parts 52, 54 and 56 forms a first region and a second region (cf. FIGS. 1 to 4 ), which are offset with respect to one another along the longitudinal extent of the replacement part 52, 54 and 56. A respective pore diameter of pores 7 of the first region differs from a respective pore diameter of pores 7 of the second region. If the replacement parts 52, 54 and 56 are supplied with compressed air, the different pore diameters result in the air volume flow which flows out of the deflection roller 1 varying in terms of amount along the longitudinal extent of the deflection roller 1.Since the exchange parts 52, 54 and 56 are exchangeable, the air volume flow can be adapted in a defined manner by removing at least one of the exchange parts 52, 54 and 56 and replacing it with a further exchange part, wherein the pore diameters and / or the pore density of the further exchange part differ from the pore diameter or the pore density of the removed exchange part 52, 54 or 56. The locking mechanism 49 can be actuated manually or by an operator in the present case. A combination of FIGS. 5A and 5B shows an actuation of the locking mechanism 49 and a removal of the outer replacement part, which is illustrated with reference numeral 52, in the arrow direction.FIG. 6 shows a schematic view of an embodiment of a cutting and spreading device 60 according to the invention. the cutting and spreading device 60 comprises two deflecting rollers 1 designed as spreading rollers 3, of which only one deflecting roller 1 or only one spreading roller 3 is shown in FIG. 6 for reasons of clarity. The spreader roller 3 shown in the exemplary embodiment according to FIG. 6 corresponds to the spreader roller 3 as has already been shown and described in FIG. 2.For the embodiment of a cutting and spreading device 60 according to FIG. 6, however, instead of the illustrated embodiment of a spreading roller 3 according to FIG. 2, two spreading rollers 3 according to FIG. 1, according to FIG. 3, according to FIG. 4 or according to FIG. 5 can also be provided which are set at an angle to one another.The cutting and spreading device 60 comprises a sensor system 32, which is designed as a camera 34 in the present case. In addition, the cutting and spreading device 60 comprises a control device 62, which in the present case comprises an evaluation unit 64 and a controller 63. The evaluation unit 64 is connected to the sensor system 32 or to the camera 34. If half of the web-shaped flat material is guided over the spreader roller 3, the evaluation unit 64 can detect the respective relative distance of half of the web-shaped flat material from the spreader roller 3 via the sensor system 32.If the detected actual distance deviates from a desired distance known to the evaluation unit 64, the control device 62 can control the pressure level prevailing in the chambers 14 and 16 or correct it in the downward direction or in the upward direction, so that the relative distance between half of the web-shaped flat material and the spreader roller 3 at least approaches a predetermined desired distance. By means of such a control, the energy consumption during spreading of web-shaped flat material can be further reduced, since in a control a very small distance between the web-shaped flat material and the spreading roller 3 can already be sufficient to be able to guide the web-shaped flat material over the spreading roller 3 without contact.The atmospheric overpressure required for producing the very small relative distance is comparatively low. A compressed air generating device not shown in FIG. 6 can therefore be operated with low power in order to form the respective low atmospheric overpressure in the chambers 14 and 16.FIG. 7 is a schematic view of an embodiment of a packaging system 80 in accordance with the invention, and the packaging system 80 receives a pair of supply rolls 82 and 84 each carrying sheet material. The web-shaped flat material is in the present case a thermoplastic packaging film which can be applied to article groups 40 and subsequently shrunk onto the respective article group 40. If a supply of web-shaped flat material of the supply roll 82 is exhausted, web-shaped flat material can be drawn from the further supply roll 84 without interruption or at least approximately without interruption, as a result of which web-shaped flat material can be provided without interruption or at least approximately without interruption.A region of the web-shaped flat material that is drawn off from the supply roll 82 is deflected by means of the deflection roller 72 and reaches as a result the working region of a separating device 90. the separating device 90 separates the web-shaped flat material in the longitudinal direction, so that two halves of the web-shaped flat material are fed to the following spreading station 67. The two halves are still connected to the supply roll 82 and are not yet separated from the supply roll 82. The separating device 90 and the spreading station 67 are part of a cutting and spreading device which is illustrated with reference numeral 60.The cutting and spreading device 60 or the spreading station 67 comprises a first pair of deflection rollers 1 and a second pair of deflection rollers 1. The deflecting rollers 1 are designed as spreader rollers 3. The spreader rollers 3 of the first pair are set at an angle to one another. The spreader rollers 3 of the second pair are also set at an angle to one another.In particular, the spreader rollers 3 can be designed according to one of the exemplary embodiments already described above with reference to FIGS. 1 to 5. As has been mentioned and described in each case in FIGS. 1 to 5, the cutting and spreading device 60 can be operated with low energy consumption by the air volume flow varying in absolute value along the longitudinal extent of the respective spreading roller 3. Embodiments with two pairs of spreader rollers 3 according to FIG. 7 have proven successful in initially pulling apart the two halves of the web-shaped flat material to a first relative distance via the first pair of spreader rollers 3 and subsequently to further increase this relative distance via the second pair of spreader rollers 3.By means of the stepwise spreading or the stepwise pulling apart of the halves of the web-shaped flat material, a risk can be kept low that the web-shaped flat material is damaged by the spreading and in particular is unintentionally stretched in the process.The thus-expanded halves of the web-shaped sheet material then leave the cutter and spreader 60 and are fed to a dancer 95. The dancer 95 includes a plurality of pulleys which can be moved relative to each other to thereby increase or decrease a supply of the exploded halves of the web-shaped sheet material stored via the dancer 95.When the halves of the web-shaped flat material leave the dancer 95, the halves are still connected to the supply roll 82 and are guided in the direction of a severing station 97. The separating station 97 is capable of separating flat packaging blanks from the halves of the web-shaped flat material and conveying them in the direction of a transport plane of the article groups 40.As FIG. 7 also shows, a plurality of articles 4 are first moved in the transport direction TR by a feed conveyor 50. Successive articles 4 of the plurality are in surface contact with one another. For the movement of the plurality of articles 4, the feed conveyor 50 comprises a circulatingly driven conveyor belt on which the plurality of articles 4 stand.A further component of the packaging system 80 is a restraining device 58 which dips between successive articles 4 of the plurality. This restraining means 58 ensures that a certain number of articles ahead are moved at a conveying speed of the feeding conveyor 50, and all subsequent articles 4 of the plurality are decelerated from the conveying speed of the feeding conveyor 50. This forms article groups 40 and transports them via the feeder 50 in the direction of a divider 59. The divider 59 comprises a plurality of rods which are not shown and are moved in a revolving manner. A respective circularly moved push rod comes into surface contact with a respective article group 40 on the rear side and accompanies the respective article group 40 during the further movement in the transport direction TR.The divider 59 is followed by a tuck-in module 61, and a gap 150 is formed between the divider 59 and the tuck-in module 61. Planar packaging blanks which have been separated from the halves of the web-shaped material via the separating station 97 are introduced via the gap 150 into the transport path of the article groups 40, so that a respective article group 40 runs onto an end region of a respective planar packaging blank. The impact module 61 has a plurality of impact rods that are moved in a revolving manner. By means of a respective tuck-in rod, the respective flat packaging blank is then folded around the respective article group 40.The tuck-in module 61 is followed in the transport direction TR by a discharge belt 73 which feeds the respective article group 40 together with the tuck-in flat packaging blank to a shrink tunnel. Herein, the respective flat packaging blank is shrunk onto the respective article group 40, so that the articles of the respective article group 40 together with the shrunk-on flat packaging blank form a bundle.FIG. 8 finally shows steps in a flow chart, as can be provided individually or according to the combination shown in FIG. 8, in various embodiments of the method 100 according to the invention. In step 110, a relative distance between a deflection roller 1 and web-shaped flat material is detected via a sensor system 32 (cf. FIG. 6 ), while the web-shaped flat material is deflected via the deflection roller 1. In order to avoid contact between the deflecting roller 1 and the web-shaped flat material, the deflecting roller 1 flows out in the direction of the web-shaped flat material to be deflected an air volume flow which varies in amount along the longitudinal direction of the deflecting roller 1. This outflowing air volume flow forms an air bed, by means of which surface contact between the deflecting roller 1 and the web-shaped flat material is prevented.In step 120, the relative distance detected by the sensor is compared with a predefined desired distance. Such a comparison can be made by means of an evaluation unit 64, as has already been illustrated and described in FIG. 6.In step 130, the outflowing air volume flow is regulated via a regulating device 62, provided that the detected relative distance deviates from a predefined desired distance. The regulation is optionally carried out in such a way that the air volume flow continues to vary in terms of amount along the longitudinal extent of the deflection roller 1 after a corresponding regulation, but increases or decreases in terms of amount in individual regions positioned along the longitudinal extent of the deflection roller 1 or in all regions along the longitudinal extent of the deflection roller 1. As a result, the energy consumption can be kept very low, wherein there is no risk, or only a low risk, that the web-shaped flat material unintentionally comes into surface contact with the deflecting roller 1.The invention has been described with reference to a preferred embodiment. It will be apparent, however, to one skilled in the art that modifications or alterations of the invention may be made without departing from the scope of the following claims.List of reference characters1 Deflection roller 3 Spreader roller 4 Article 5 First region 6 Second region 7 Pores 8 Pores 14 First chamber 16 Second chamber 17 Overpressure region 18 Adjustment mechanism 19 Wall 21 Slide 23 Seal 24 Compressed air tube 25 Adjustment element 26 Compressed air tube 27 External hexagon 28 Defined surface 32 Sensor system 34 Camera 40 Article group 41 First channel 42 Second channel 45 Housing 47 Compressed air connection 49 Locking mechanism 50 Feeder 52 First replacement part 54 Second replacement part 56 Third replacement part 58 Retaining device 59 Adjuster 60 Cutting and spreading device 61 Tuck-in module 62 Regulating device 63 Regulator 64 Evaluation device 67 Spreading station 72 Deflection roller 73 Outlet belt 80 Packaging system 82 Supply roller 84 Supply roller 90 Separating device 95 Dancer 97 Separating station TR Transport direction

Claims

Deflecting roller (1) for web-shaped flat material, wherein the deflecting roller (1) is designed for the outflow of an air volume flow supporting the flat material to be deflected, which outflow of air volume flow varies in terms of amount in different regions (5, 6) positioned along the longitudinal extent of the deflecting roller (1).Deflecting roller (1) according to Claim 1, which comprises a multiplicity of pores (7, 8) arranged along the longitudinal extent of the deflecting roller (1) for the outflow of the air volume stream.The deflection roller (1) according to claim 2, wherein a pore density increases or decreases along the longitudinal extension of the deflection roller (1).The deflection roller (1) according to any one of claims 1 to 3, wherein the deflection roller comprises pores (7, 8) having different pore diameters.Deflecting roller (1) according to Claim 4, wherein a plurality of pores (7) having a first pore diameter is arranged in a first region (5) positioned along the longitudinal extent of the deflecting roller (1), and a plurality of pores having a second pore diameter is arranged in a second region (6) positioned along the longitudinal extent of the deflecting roller (1), which region is offset with respect to the first region (5) along the longitudinal extent of the deflecting roller (1), which second diameter is enlarged or reduced with respect to the first diameter.Deflecting roller (1) according to one of Claims 1 to 5, which forms at least two chambers (14, 16) which are offset with respect to one another along their longitudinal extent and can be subjected to different pneumatic pressures, and to which at least two chambers (14, 16) are assigned respective dedicated pores (7) of the deflecting roller for the outflow of the air volume stream.Deflecting roller (1) according to Claim 6, in which the at least two chambers (14, 16) offset with respect to one another along their longitudinal extent are completely fluidically decoupled from one another.Deflecting roller (1) according to Claim 6, which forms an overpressure region (17), wherein the first chamber (14) is connected to the overpressure region (17) in each case by flow technology via a first channel (41) and the second chamber (16) is connected to the overpressure region (17) via a second channel (42).Deflecting roller (1) according to Claim 8, comprising an adjusting mechanism (18), by means of which an opening cross section of the first channel (41) and / or an opening cross section of the second channel (42) can be adjusted.Deflecting roller (1) according to Claim 8, wherein a proportional valve is assigned to the first channel (41) and / or wherein a proportional valve is assigned to the second channel (42).Deflection roller (1) according to one of Claims 2 to 10, in which the multiplicity of pores (7) is positioned exclusively in a defined surface of the deflection roller, which defined surface narrows along the longitudinal extent of the deflection roller and in this case runs in particular trapezoidally or V-shaped.Use of a deflecting roller (1) according to one of Claims 1 to 11 as an spreading roller (3) for web-shaped flat material.Cutting and spreading device (60) for web-shaped flat material, comprising - a separating device (90) for separating the web-shaped flat material into at least two halves, - at least one deflecting roller (1), in particular a deflecting roller (1) according to one of Claims 1 to 11, which is designed as at least one spreading roller (3) for the at least two halves, and which is designed for the outflow of an air volume flow supporting the flat material to be deflected, which outflow of air volume flow varies in terms of amount in different regions (5, 6) positioned along the longitudinal extent of the deflecting roller (1), and - a compressed air generating device which is connected in terms of flow to the at least one deflecting roller (1) for the outflow of the air volume flow, such that the outflow of air volume flow varies in terms of amount in different regions (5, 6) positioned along the longitudinal extent of the deflecting roller (1).Cutting and spreading device (60) according to Claim 13, comprising a regulating device (62) and at least one sensor system (32), wherein the regulating device (62) is designed via the at least one sensor system (32) for determining a relative distance between the deflecting roller (1) and the web-shaped flat material located in the region of the deflecting roller (1), and wherein the regulating device (62) is configured and equipped in such a way that it regulates the outflowing air volume flow as required if the determined relative distance deviates from a setpoint distance stored on the regulating device (62).Cutting and spreading device (60) according to Claim 14, in which the at least one sensor system (32) is formed by at least one camera (34).Packaging system (80) comprising a cutting and spreading device (60) according to one of claims 13 to 15, wherein the packaging system is designed for severing sheet-like packaging blanks from the at least two spread halves of the web-like flat material and for applying the severed sheet-like packaging blanks to article groups (40).Method (100) for deflecting web-shaped flat material via at least one deflecting roller (1), in particular via at least one deflecting roller (1) according to one of Claims 1 to 11, in which method (100) for supporting the web-shaped flat material an air volume flow is discharged from the at least one deflecting roller (1) in such a way that the discharged air volume flow varies in terms of amount along the longitudinal extent of the at least one deflecting roller (1).Method (100) according to claim 17, in which a relative distance between the at least one deflection roller (1) and the web-shaped flat material located in the region of the at least one deflection roller (1) is determined by sensor means and the outflowing air volume flow is adjusted as required by means of a control if the determined distance deviates from a predetermined desired distance.Method according to Claim 17 or Claim 18, in which the web-shaped flat material is separated into at least two halves and the at least two halves are spread apart via the at least one deflecting roller (1).Method according to claim 19, in which planar packaging blanks are separated from the at least two separated and spread apart halves and are applied to article groups (40).Method according to one of Claims 17 to 20, in which the outflow of air volume flow is varied as a function of a parameter of the flat material or as a function of the production speed, in particular by means of a control and / or a regulation.

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