Spreading device

Description

[0001] The invention relates to a spreading device for several strips of material web separated from a material web by a material web cutting device, wherein the strips of material web are fed to the spreading device along a transport path in a feed plane and leave the spreading device in a discharge plane in order to subsequently be transported parallel to each other to a winding shaft device and wound onto a common winding shaft, wherein the spreading device has two deflection elements, each extending transversely to the transport path, which are designed and arranged such that the strip spacing between two adjacent strips of material web guided successively along a transport path over the first and second deflection element is greater in the discharge plane than in the feed plane.

[0002] Numerous material web slitting devices are known from practical experience, which can produce several adjacent strips of material from a single web, such as paper or plastic film. These strips are then wound onto individual winding shafts and stored for later use. It is essential to ensure that two adjacent strips of material originating from the same web are sufficiently separated during and after winding so that each individual strip can be separated from its neighboring strip. Furthermore, the resulting strips must be stored independently and ready for subsequent use.

[0003] Cutting machines are known that have a winding shaft assembly with two or more winding shafts. After the cutting process, adjacent strips of material are cut and fed to different winding shafts and wound onto them. Since adjacent material strip rolls are wound onto different winding shafts, a sufficient distance can be easily maintained. If a larger number of material strip rolls are produced simultaneously, and therefore several material strips that were not originally directly adjacent are wound onto a common winding shaft, the distance between two material strip rolls wound side by side on the same winding shaft corresponds at least to a distance equal to the width of a material strip that was originally located between them and wound onto a different winding shaft in the winding shaft assembly.However, it is considered a disadvantage that the strips of material originating from one material web have to be wound onto two or more different winding shafts.

[0004] It is also known from practice that a web of material, not yet split into multiple strips, is pulled apart transversely to one direction of the transport path, for example, using a spreading roller, before cutting. The web is then fed to the material cutting device with a transverse tension imposed by the spreading rollers and cut into multiple strips. After the cutting process, the individual strips lose the transverse tension and therefore contract slightly, creating a small gap between two adjacent strips.As the number of individual strips of material that are separated from the material web increases, the individual gaps created between two adjacent strips of material become smaller and smaller, and an undesirable tendency for the adjacent transported and wound strips of material to collide or run into each other inevitably increases.

[0005] It is also known that a spreading device is arranged after the material web cutting device, with which the strips of material transported side by side along the transport path are spread apart before they are wound up in the winding shaft device. Rotatably mounted spreading rollers, with which the desired spreading of the material web strips is to be effected, often have a number of individual roller segments over which the individual material web strips are deflected and thereby spread apart, or separated from each other, and thus the strip spacing between two adjacent material web strips is increased.Particularly in narrow-cut applications, where a large number of relatively narrow strips are produced from a single web, conventional spreading rollers can no longer provide a dedicated segment for each individual strip. This leads to distortion of the strips during transport over the spreading roller, resulting in undesirable transverse stresses within a strip and lateral displacement along its transport path. It has also been shown that the spreading effect, and thus the resulting gap between two adjacent strips, depends on the web tension generated along the transport path, which is necessary for the strips' movement along that path.Particularly during acceleration and deceleration processes, such as those that occur during the operation of these systems, the web tension generated along the transport direction cannot be reliably maintained, which in turn can lead to lateral displacement of the individual web strips. Undesired displacement can also be attributed to friction generated during the transport of the individual web strips over the spreading roller. Due to friction, as well as wear and tear on the spreading device over its service life, additional deviations can occur in the deflection of the individual web strips caused by the spreading device, which in turn can impair reliable separation of the individual web strips.

[0006] US 4176775 A describes a device that represents the closest prior art for the invention.

[0007] It is therefore considered an object of the present invention to design a spreading device already known from the prior art in such a way that strips of material web transported side by side through the spreading device are spread as reliably as possible and then have a sufficient distance from each other in order to subsequently be wound onto a common winding shaft without adjacent wound material web strip rolls touching each other.

[0008] This problem is solved according to the invention by the fact that the deflection elements are arranged in a rotationally fixed manner, and that each deflection element has a number of openings in a transport contact area of ​​the deflection shell surface covered by the material web strips transported over it, through which compressed air can be blown in order to create a friction-reducing air layer between the material web strips and the deflection shell surfaces of the deflection elements in the transport contact area.The rotationally fixed arrangement of the deflection elements ensures that a precisely defined geometry of the deflection surfaces of the deflection elements, relative to the material web strips being transported and deflected, is maintained even over a long service life of the spreading device. This geometry is not affected by the rotational movement of the deflection elements or by insufficiently precise bearings of the rotating deflection elements, as is conventionally known. The formation of an air gap between the transport contact areas of the deflection surfaces of the deflection elements and the transported material web strips largely reduces friction between the material web strips and the stationary deflection surfaces of the deflection elements.Undesirable friction-related abrasion and wear of the deflection elements can be reduced to such an extent that no significant change in the shape of the deflection shell surfaces occurs over the intended service life of the spreading device, or a service life limited by abrasion or wear of the deflection elements can be significantly extended.

[0009] The friction-reducing air layer between the deflection surfaces of the deflection elements and the material web strips transported over them and deflected along the deflection surfaces also reduces undesirable transverse stresses and distortions of individual material web strips, so that after leaving the spreading device, a significantly reduced undesirable lateral offset of individual material web strips occurs.

[0010] To create an air layer that is as homogeneous as possible and does not impede the desired deflection of the individual web strips, a large number of openings are advantageously provided within the transport contact areas of the deflection surfaces of the deflection elements. The individual openings can be arranged and designed to be distributed regularly or irregularly across the transport contact areas. The air pressure of the compressed air supplied to each deflection element is advantageously set such that, on the one hand, a friction-reducing air layer forms across the entire transport contact area of ​​the deflection surface, and on the other hand, the smallest possible distance is created between the deflection surface and the web strips transported over it, so as not to impede the deflection and lateral displacement of the web strips caused by the geometry of the deflection surfaces.

[0011] According to an advantageous embodiment of the invention, the deflection surfaces of the deflection elements are made of a porous and air-permeable material. A suitable porous material can, for example, be produced from a powder or granules by a sintering process. It is also conceivable that the porous material is produced by foaming a ceramic or a suitable plastic or metal material. For each deflection element, one or more deflection elements made of the porous and air-permeable material can be provided, with an outer surface of the deflection element or elements forming the deflection surface of the respective deflection element.At least the respective transport contact surface within the deflection jacket surfaces is made of the porous and air-permeable material, if, depending on the arrangement and use of the deflection elements, the material web strips do not lie against the deflection element over the entire deflection jacket surface, but only in a partial area of ​​the transport contact surface, or are transported past it and thereby deflected.

[0012] According to an alternative embodiment of the invention, the deflection surfaces or the transport contact surfaces of the deflection elements are made of perforated sheet metal or a perforated thin-walled material layer. Methods are known in practice for creating or forming very small holes with a small opening diameter in sheet metal or a material layer. For example, small holes can be created in thin sheet metal or a plastic layer using a high-energy laser. A large number of holes can be produced in a short time using a pulsed laser. Suitable laser drilling devices are known in practice.The deflection surfaces or transport contact surfaces of the deflection elements can be made not from sheet metal but also from another suitable material, such as plastic or a composite material consisting of several layers arranged on top of or next to each other. The material should have a surface that is as smooth and low-friction as possible and generate minimal abrasion during operation. This ensures that the deflection elements can operate with minimal wear over a long service life and that the web strips can glide over the deflection surfaces or transport contact surfaces at high speeds.

[0013] Advantageously, it is optionally provided that the deflection surfaces or the transport contact surfaces of the deflection elements have a number of holes with an opening diameter of less than 0.5 mm, preferably less than 0.2 mm. It has been shown that a particularly high number of especially small holes creates a particularly homogeneous and precisely controllable air layer across the entire transport contact area of ​​the deflection surface, which effectively reduces the friction of the material web strips passing over it. The cross-sectional area of ​​the holes can be approximately circular or oval, elliptical, or polygonal.By appropriately orienting non-circular cross-sectional areas relative to the transport path, which is specified for a number of holes or for all holes, relevant properties of the resulting air layer can be influenced and specified as favorably as possible.

[0014] The desired shape and geometry of the deflection surface for redirecting the material web strips can be created either during the manufacturing of the deflection elements or subsequently through shaping of the individual elements, thus allowing for extremely precise control. The rotationally fixed arrangement of the individual deflection elements enables highly precise control of their arrangement and orientation, and consequently, of the individual deflection surfaces, ensuring the most ideal, distortion-free deflection of the individual material web strips by the spreading device.

[0015] According to the invention, the two deflection elements are arranged and designed such that the feed plane and the discharge plane are parallel to and offset from each other. The greater the offset between the feed plane and the discharge plane for the material web strips transported along the transport path, the greater the distance that can be set between adjacent material web strips. However, it has been shown that an offset between the feed plane and the discharge plane of less than 20 centimeters is sufficient to create an adequate distance even with a large number of material web strips that have been separated from a common material web. The deflection elements are also designed according to the invention such that the material web strips are transported between the two deflection elements at approximately a right angle relative to the feed plane and the discharge plane.Depending on the original width of the material web and the number of material web strips separated from this material web, a less pronounced deflection may also be sufficient and appropriate.

[0016] According to an advantageous embodiment of the invention, the deflection elements are designed as circular segments within a cross-sectional area extending along the transport path. To deflect a strip of material by approximately 90 degrees, only a correspondingly large segment of a deflection surface, for example, an arc-shaped one, is required, extending over an arc angle of slightly more than 90 degrees. Since the deflection elements are arranged to be rotationally fixed, it is not necessary to design them as cylindrical. Only the transport contact area provided for deflecting the strips of material and the deflection surfaces required for this purpose are needed.The circular segment design ensures a uniform deflection of the web strips across the transport contact area of ​​the deflection surface, thereby resulting in the most uniform stress possible on the web strips during transport through the spreading device. These circular segment deflection elements can also be arranged in a space-saving manner within a larger system, which can unwind a web from a roll and separate it into individual strips, which can then be rewound onto strip reels. Instead of a circular arc-shaped deflection surface, other shapes, such as oval or elliptical, may also be advantageous.

[0017] It has proven particularly advantageous for spreading the individual web strips that a deflection surface of each deflection element has a deflection curvature along the transport path of a web strip and a spreading curvature extending across all web strips perpendicular to the transport path. The spreading curvature can be constant perpendicular to the transport path. The deflection curvature along the transport path can also be constant and identical for all web strips. It is also conceivable that a separate deflection curvature is specified for each web strip.The deflection curvature can vary depending on the width and material of the material strips, even within a single strip, if this promotes reliable spreading of the individual strips relative to each other and reduces subsequent undesirable lateral displacement. The desired geometry and shape of the deflection surface can be precisely defined and produced, particularly when the deflection surface is made from a porous and air-permeable material, through shaping of the porous and air-permeable material.

[0018] It is also conceivable that the spreading curvature of a deflecting element, extending across all material web strips, is formed by subsequently forming a deflecting element blank that is initially not curved in a spreading direction. For many applications, the required or advantageous spreading curvature is relatively small, and the spreading curvature radius is often orders of magnitude larger than the deflecting element's extent perpendicular to the transport path of the material web strips. It has been shown that, particularly with deflecting elements whose deflecting surface or transport contact surface is formed by a perforated sheet or a perforated material layer, the desired spreading curvature can be generated and specified by subsequently forming a deflecting element blank.The deflection element blank can initially be manufactured with a straight path in this direction, which significantly simplifies and reduces the cost of its production. Forming processes are known from practical experience that can precisely generate and define even very large radii of curvature for the formed deflection element.

[0019] It has proven to be a particularly advantageous embodiment of the invention that the deflection surfaces of the two deflection elements form an equal wrapping length for each strip of material along the transport path. In a circular segment-shaped design of the deflection elements, the wrapping length of each strip of material is composed of the two wrapping angles that the transport path dictates for a strip of material along the two deflection surfaces of the deflection elements. Equal wrapping lengths, at least for adjacent or for all strips of material, promote a uniform web tension along the transport path and thus enable simple and reliable control of the web tension for the most uniform and reliable transport of the strips of material along the transport path.

[0020] The following section explains various embodiments of the invention in more detail, which are illustrated schematically and by way of example in the drawing. It shows: Fig. 1 a perspective view of a spreading device with two deflection elements, wherein several adjacent strips of material web are guided along a transport path around the deflection elements and thereby deflected, Fig. 2 a top view of a deflection element, Fig. 3 a cross-sectional view through the in Fig. 2 The deflection element shown is located along a section line III - III in Fig. 2 , Fig. 4 a sectional view through a differently designed deflection element, Fig. 5 a sectional view of a deflection element with a different design, and Fig. 6 a top view of a product manufactured by forming and, for example, in Fig. 5 shown deflection element.

[0021] In Figure 1Figure 1 shows a schematic representation of an exemplary spreading device 1. The spreading device 1 has a first deflecting element 2 and a second deflecting element 3. A material web 5, already separated into several material web strips 4, is fed into the spreading device 1 in a feed plane 6. The material web strips 4 are deflected by the two deflecting elements 2 and 3 and exit the spreading device 1 in a discharge plane 7 that is parallel to the feed plane 6. During transport along a transport path indicated by an arrow 8, the material web strips 4 are not only deflected by the deflecting elements 2 and 3, but are also spread apart relative to each other, so that in the discharge plane 7 the strip spacing 9 between adjacent material web strips 4 is greater than the strip spacing in the feed plane 6 before entering the spreading device 1.

[0022] Each of the two deflection elements 2, 3 extends transversely to the transport path over the entire width of the supplied material web 5, or over the entire width of the spread material web strips 4. The deflection elements 2, 3 are located in a cross-sectional area running along the transport path, as is also the case in Figure 3As shown schematically, the deflection element 2, 3 is designed in the shape of a circular arc segment. Each deflection element 2, 3 has a base body 10 and a shell element 11 made of a porous and air-permeable material. An outwardly facing outer surface of the shell element 11 forms a deflection surface 12 for the material web strips 4 transported over the deflection element 2, 3. Within a transport contact area 13 of the deflection surface 12, the material web strips 4 rest against the deflection surface 12, separated only by a narrow air cushion, and are thereby deflected. The transport contact area 13, or transport contact surface, is the area of ​​the deflection surface 12 against which the material web strips 4 rest during transport along the transport path. The transport contact area 13 can coincide with the deflection surface 12 or be a sub-area of ​​the deflection surface 12.

[0023] The outer shell element 11 is fixed to the base body 10 of the deflecting element 2, 3 such that an interior space 14 is formed between the outer shell element 11 and the base body 10. Compressed air can be supplied to the interior space 14, which is then blown out through the numerous individual openings 15 of the porous material of the outer shell element 11 and escapes. This creates a friction-reducing layer of air in the transport contact area 13 between the deflecting shell surface 12 and the material web strips 4 transported over it.

[0024] The deflection surface 12 of the deflection element 2, 3, formed by the shell element 11, exhibits a spreading curvature extending across all material web strips 4 transversely to the transport path, which occurs when in Figure 2The top view of a deflection element 2, 3 shows the outer contour 16 of the shell element 11. In the embodiment shown in the figures, the spreading curvature is constant over the entire extent of the deflection element 2, 3 transversely to the transport path. In practice, a radius of curvature of many meters is often sufficient, and the spreading curvature in the figure is shown according to Figure 2 The illustration is significantly exaggerated for illustrative purposes only.

[0025] In the Figures 4 and 5 Further variants of a deflection element 2, 3 are shown as examples. In the case of the Figure 4In the illustrated embodiment, the deflection element 2, 3 has a circular arc-segment-shaped outer shell element 11 made of a porous material, which is placed on the base body 10. The shape of the base body 10 in the areas adjacent to the outer shell element 11 is such that a continuous and approximately step-free and seamless surface is formed at the transition from the base body 10 to the deflection shell surface 12 formed by the outer shell element 11.

[0026] The base body 10 has several funnel-shaped interior spaces 14 adjacent to the outer shell element 11, which almost completely cover a contact surface 17 of the outer shell element 11 facing the base body 10. Compressed air can be blown into the outer shell element 11 over a large area through these interior spaces 14. After exiting through the porous material of the outer shell element 11, the compressed air forms a friction-reducing air layer for the material web strips 4 sliding over it. The compressed air can be supplied, for example, via compressed air lines 18, which are fitted and pressed into compressed air channels 19 formed in the base body 10.

[0027] During a Figure 5In the schematically depicted embodiment, the deflecting element 2, 3 has a perforated sheet 20 curved along the transport path in a quarter circle. The perforated sheet 20 is made of a thin sheet into which a large number of spaced-apart holes 21 have subsequently been drilled using a laser drilling device. The opening diameter of the holes 21 is preferably significantly less than 0.5 mm. The perforated sheet 20 is connected to the base body 10 along a circumferential edge 22. The transition from the base body 10 to the perforated sheet 20 is designed to be as friction-free as possible.

[0028] The basic body 10 can, for example, have a shape such as that shown in Figure 5 is only shown schematically. It is also possible that the base body 10 has a tubular shape with a longitudinally extending slot into which the perforated sheet 20 is fitted.

[0029] This is merely schematic in Figure 6 The deflection element 2, 3 shown is produced from a straight forming blank by a forming process that creates the spreading curvature. The forming blank is first formed in a longitudinal direction of the deflection element 2, 3, which is perpendicular to a direction in the Figures 3 to 5The cross-sectional area of ​​the deflection element 2, 3 shown is produced in a straight line, which, with regard to the base body 10, can be achieved, for example, by extrusion or by a suitable, cost-effective forming process. Subsequently, the initially straight deflection element blank can be deformed and given the required spreading curvature by a suitably performed forming step. This forming step can also be carried out very precisely and cost-effectively, so that a particularly economical production of the deflection element 2, 3 is possible.

Claims

1. A spreading device (1) for multiple material web strips (4) cut from a material web (5) by a material web cutting device, wherein the material web strips (4) are guided along a transport path in a feed plane (6) of the spreading device (1) and leave the spreading device (1) in a discharge plane (7) to then be transported parallel to one another to a winding shaft device and wound on a common winding shaft, wherein the spreading device (1) has two deflecting elements (2, 3), each running transversely to the transport path, which are designed and arranged in such a way that a strip spacing (9) between two material web strips (4) guided adjacent to one another along a transport path one after the other over the first and second deflecting elements (2, 3) is greater in the discharge plane (7) than in the feed plane (6), wherein the deflecting elements (2, 3) are arranged to be non-rotating, and wherein each deflecting element (2, 3) has a number of openings (15) in a transport contact area (13) of a deflecting lateral surface (12) of the deflecting element (2, 3), which is covered by the material web strips (4) transported over it, through which compressed air can be blown out in order to be able to create a friction-reducing air layer between the material web strips (4) and the deflecting lateral surfaces (12) of the deflecting elements (2, 3) in the transport contact area (13), characterised in that: - both deflecting elements (2, 3) are arranged and designed such that the feed plane (6) and the discharge plane (7) are offset parallel to one another, and - the deflecting elements (2, 3) are designed such that the material web strips (4) are transported between the two deflecting elements (2, 3) approximately at a right angle relative to the feed plane and the discharge plane.

2. The spreading device (1) according to claim 1, characterised in that the deflecting lateral surfaces (12) or the transport contact surfaces (13) of the deflecting elements (2, 3) are produced from a porous and air-permeable material.

3. The spreading device (1) according to claim 1, characterised in that the deflecting lateral surfaces (12) or the transport contact surfaces (13) of the deflecting elements (2, 3) are produced from a perforated sheet or from a perforated thin-walled layer of material.

4. The spreading device (1) according to claim 3, characterised in that the deflecting lateral surfaces (12) or the transport contact surfaces (13) of the deflecting elements (2, 3) have a number of holes with an opening diameter of less than 0.5 mm, preferably less than 0.2 mm.

5. The spreading device (1) according to any one of the preceding claims, characterised in that the deflecting elements (2, 3) are designed in the shape of segments of a circle in a cross-sectional area extending along the transport path.

6. The spreading device (1) according to any one of the preceding claims, characterised in that a deflecting lateral surface (12) of each deflecting element (2, 3) has a deflecting curvature along the transport path of a material web strip (4) and has a spreading curvature extending across all material web strips (4) transversely to the transport path.

7. The spreading device (1) according to claim 6, characterised in that the spreading curvature of a deflecting element (2, 3) extending over all the material web strips (4) is formed by subsequent reshaping of a deflecting element blank that is initially not curved in a spreading direction.

8. The spreading device (1) according to any one of the preceding claims, characterised in that the deflecting lateral surfaces (12) of both deflecting elements (2, 3) along the transport path form a wrap-around section of equal size for each material web strip (4).