Abstract:
A support for a material web for use with a longitudinal cutting device for cutting the material web, includes a support shaft having an axis of rotation. At least one bearing mechanism positions the at least one support shaft, wherein the at least one bearing mechanism has an axis of rotation outside of the axis of rotation of the support shaft.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims the priority of German Patent Application No. 102 06 323.0 filed Feb. 14, 2002, the disclosure of which, together with the disclosure of each U.S. and foreign patent and patent application mentioned below, is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a support for a material web, especially a paper web, on a cutting device for the material web, in particular a longitudinal cutting device on a machine in the paper-processing industry. The invention furthermore relates to the use of a support of this type, to an arrangement for cutting a material web, especially a paper web, and to a machine in the paper-processing industry.  
           [0003]    A format cutter manufactured by the assignee of the present application and marketed under the designation SLK is already known. For this cutter, several paper webs are joined in front of a longitudinal cutting device and are then cut into strips of paper with a predetermined width, for example 210 mm for DIN A 4. The longitudinal cutting device is a stationary longitudinal cutting unit for making a tangential cut.  
           [0004]    The longitudinal cutting station for this paper processing machine comprises an upper blade and a lower blade, between which at least one paper web is guided through and is cut into paper strips. German patent DE 28 21 956 C2 and German unexamined published patent application DE 39 06 376 A1 disclose devices for the longitudinal cutting of paper webs.  
           [0005]    Several longitudinal cutting blades are used in a parallel, side-by-side arrangement to cut a paper web, wherein the spacing between these cutting blades can determine the format. With the format-flexible longitudinal cutting blades, the paper between the individual longitudinal cutting blade holders cannot be supported since the blades are displaced transverse, that is crosswise to the direction of paper web movement, depending on the format. The paper is tensioned through a very slight looping across the lower blades. Guide rollers are arranged in front of and behind the longitudinal cutting blades. These guide rollers are far removed from the paper cutting location since these rollers generally have a large diameter of up to 150 mm to ensure sufficient stability over the complete working width of the longitudinal cutting device.  
           [0006]    The tightly held paper, however, has a tendency to sag in those locations where it is not supported by the lower blades, meaning between the rollers and/or the longitudinal cutting blades. This sag is greater the farther the rollers are removed from the longitudinal cutters and the farther the longitudinal cutters are spaced apart in each case. In addition, spacing the rollers far apart favors the increased formation of folds in the longitudinal direction in the paper webs to be cut.  
         SUMMARY OF THE INVENTION  
         [0007]    Thus, it is an object of the present invention to support the conveyed paper webs on the longitudinal cutting device and to improve the edge retention at the longitudinal cutting blades.  
           [0008]    The above and other objects are achieved according to the invention by the provision of a support for a material web for use with a longitudinal cutting device for cutting the material web, comprising: a support shaft having an axis of rotation; and at least one bearing means for positioning the at least one support shaft, the at least one bearing means having an axis of rotation outside of the axis of rotation of the support shaft.  
           [0009]    The object of the invention is thus solved first of all in that the support as defined in the above is designed to have at least one support shaft and at least one bearing means for the rotatably positioning the support shaft, wherein the bearing means has an axis of rotation outside of the axis of rotation for the support shaft. The support according to the invention causes the paper web to be supported directly in front of/or behind the cutting location of cutting device, which is normally stationary. The positioning of the support shaft according to the invention makes it possible to use thin shafts since a bending of the shafts caused by the bearing means according to the invention is prevented. By reducing the distance between the support shaft and the cutting location, the support can be arranged in the intake area and/or the discharge area for the cutting device, so that the transverse bending of the material web between the cutting blades is reduced or even prevented. In addition, arranging the support in the intake area and/or the discharge area results in less looping of the material web on the lower blade and the creation of fewer longitudinal folds in the paper web.  
           [0010]    Since the bearing means is no longer positioned co-linear with the axis of rotation of the support shaft, it is advantageous if the bearing means is embodied in the form of at least one bearing device that is preferably arranged along the support shaft.  
           [0011]    According to one advantageous modification, the bearing device is provided with at least two bearing elements.  
           [0012]    It is furthermore advantageous if the bearing device and/or the bearing elements rotate, such that the support shaft can also rotate.  
           [0013]    One advantageous modification provides that the bearing device or the bearing elements at least make direct contact with the support shaft, such that the support shaft can roll off the bearing device or the bearing elements.  
           [0014]    The bearing elements according to another advantageous modification of the invention are preferably designed to be cylindrical rotating members.  
           [0015]    Alternatively, the bearing elements may be advantageously embodied as disc-shaped elements or roller bearings.  
           [0016]    The bearing device and/or the bearing elements are furthermore advantageously arranged axially-parallel to the support shaft, preferably in the longitudinal direction of the support shaft and at predetermined distances to each other. As a result, the support shaft is strategically supported at specific locations, for example between the lower blades. The weight of the support shaft is additionally reduced in this way since either, the bearing device or the bearing elements are formed by sectors. Strategically supporting the shaft at several locations along the support shaft prevents bending in the longitudinal direction of the support shaft.  
           [0017]    At least one holding device for the support shaft is provided to prevent the shaft from jumping out of the bearing device.  
           [0018]    In particular, the holding device advantageously holds the support shaft without making contact, which simplifies the construction.  
           [0019]    Advantageously the holding device comprises at least one magnet. The magnetic forces hold the support shaft inside the bearing device so that the support shaft can rotate in the bearing device and/or in the bearing elements.  
           [0020]    The invention furthermore provides that holding devices and/or magnets are installed with predetermined spacing along the support shaft.  
           [0021]    According to one advantageous embodiment of the invention, at least one holding device is arranged between two bearing devices or at least one bearing device is arranged between two holding devices. An alternating sequence of bearing devices and holding devices is consequently formed, which reliably supports and securely holds the support shaft.  
           [0022]    It is furthermore advantageous if at least one supporting structure is provided for supporting the hearing device and/or the holding device, so that the bearing device and/or the holding device together with the support shaft form a compact arrangement. The supporting structure also permits a good positioning of the support in the intake area and the discharge area of the longitudinal cutting blades. The supporting structure furthermore results in a compact design, thus making it easy to replace the support.  
           [0023]    According to a further aspect of the invention, there is provided a method of supporting a material web in at least one of an intake area and a discharge area of a longitudinal cutting device for the material web, the method comprising utilizing the support as described above.  
           [0024]    According to yet another aspect of the invention, there is provided an arrangement for cutting a material web, especially a paper web. This arrangement comprises at least one cutting device; in particular a longitudinal cutting device, on a machine in the paper processing industry, as well as a support of the type as described in the above.  
           [0025]    One modification of the arrangement according to the invention provides that the supporting structure is adjustable, in particular with respect to height. By using an adjustable supporting structure together with the support shaft, the support can be positioned extremely close to the cutting location for the longitudinal cutting device.  
           [0026]    According to still another aspect of the invention, there is provided a method of supporting a paper web in a machine in the paper-processing industry, comprising utilizing the support as described above. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    The invention is described in the following without restricting the general inventive idea, with the aid of exemplary embodiments and by referring to the drawings, to which we refer for all details of the invention that are not explicitly explained in the text. Shown are in:  
         [0028]    [0028]FIG. 1 is known in the prior art.  
         [0029]    [0029]FIG. 2 is a cross section through a cutting arrangement according to the invention.  
         [0030]    [0030]FIG. 3 is a plan view of one of the supports shown in FIG. 2.  
         [0031]    [0031]FIG. 4 is a side view of the support shown in FIG. 3.  
         [0032]    [0032]FIG. 5 is a sectional view of a cutting arrangement with supports according to the invention.  
         [0033]    [0033]FIG. 6 is a cross-sectional view a cutting arrangement according to another embodiment of the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]    In the Figures described herein, the same elements are given the same reference numbers and will not introduced anew in each case.  
         [0035]    [0035]FIG. 1 shows an arrangement for cutting a paper web  5  in a longitudinal cutting station of a paper-processing machine. The longitudinal cutting station comprises a longitudinal cutting device  2  with an upper knife  3  and a lower knife  4 , which make a tangential cut through the paper web that moves between the lower knife and the upper knife.  
         [0036]    Respectively one support shaft  6  is arranged in front of the longitudinal cutting device  2  and behind the longitudinal cutting device  2  to support the paper web  5  in transverse direction, meaning in a plane that is perpendicular to the drawing plane. Owing to the width of the paper web  5 , it is necessary for the support shafts  6  to have sufficient stability across the complete width of the paper web. For this, the support shafts  6  are designed to have a correspondingly large diameter of up to 150 mm. Based on this large diameter for the support shafts  6 , however, these support shafts  6  can only be arranged at a correspondingly large distance to the cutting location of the paper web  5 .  
         [0037]    To ensure a precise cutting, the paper web  5  must be tensioned with only a very slight looping across the lower knife  4  and other parallel arranged lower knives. The paper  5  that is tensioned in the longitudinal cutting station  2  is not supported between two lower knives in the region of the cutting plane, so that the paper web  5  assumes a direct connection between the support shafts  6 . As a result, the paper web sags between the lower knives  4  and the support shafts  6 , the sag being depicted by the dashed line  7 . The height of the surface curvature depends on the distance between the side-by-side arranged lower knives and the distance between the support shafts in the intake area and/or the discharge area of the longitudinal cutting device  2 . A large distance between the support shafts  6  favors the formation of longitudinal folds in the paper web  5 . With format-flexible longitudinal cutters this leads to edge-retention problems.  
         [0038]    To improve the edge-retention for the longitudinal cutting device  2 , the invention therefore provides for supporting the paper web  5  as closely as possible in front of and behind the cutting location. As a result, the sagging or curvature of the paper web  5  between the parallel-arranged lower knives is clearly reduced as compared to the prior art. With some types of paper, it is even possible to completely prevent the sagging of the paper web.  
         [0039]    [0039]FIG. 2 shows a cross section through a longitudinal cutting device  2  with respectively one support  10  according to the invention for the material web  5  arranged in the intake area and in the discharge area of the paper web  5 . The basic design for the support  10  is shown schematically. The support  10  is respectively provided with a support shaft  11 , which has the same function as the support shaft  6  in FIG. 1. The support shaft  11  is positioned such that it can rotate with the aid of several bearings devices  12 , for example cylindrical bearings, ball bearings or disc bearings, arranged along the support shaft  11 . To make sure that the support shaft  11  can rotate inside the support  10 , the underside of support  10  is provided with a magnet  13 , which holds the support shaft  11  inside the support  10  with the aid of magnetic forces.  
         [0040]    In contrast to the prior art, a support shaft with clearly smaller diameter than the support shaft  6  according to the prior art arrangement shown in FIG. 1 can be used since the bearing devices are positioned to rotate about respective axes outside of the axis of rotation of the support shaft  11 . In addition, the bearings  12  not only function to position the support shaft  11  so that it can rotate, but also result in a stabilization of the support shaft  11  over the complete working width of the longitudinal cutting device  2 . The bearing devices  12  are thus spaced apart by short distance to support the thin support shafts  11  so that the support shaft  11  cannot bend. By using a thin support shaft  11 , the distance between the point where the material web  5  rests on the support shaft  11  and the cutting location in the longitudinal cutting device  2  can be shortened noticeably as compared to the known arrangement shown in FIG. 1.  
         [0041]    Sectional details of a support  10  in an embodiment according to the invention are shown in FIG. 3 in a view from above and in FIG. 4 in a view from the side. The support  10  is provided with a transverse bar  15  on which the support shaft  11  is arranged. The support shaft  11  is arranged such that it can rotate on the ball bearings  12 . The ball bearings  12  are delimited and held in place on both sides by holders  14 , wherein the ball bearings  12  and the holders together form a bearing device  18  for the support shaft  11 .  
         [0042]    Other embodiments within the scope of the invention, but not illustrated herein, include, for example, disc-shaped rotational elements as bearing devices.  
         [0043]    The bearing devices  18  are distributed over the complete length of support shaft  11  spaced apart evenly, to reliably support the support shaft  11 . An end holder  16  is mounted on a transverse bar  15  at the end of the support shaft  11  for holding the end of support shaft  11 .  
         [0044]    Respectively one magnet  13  is arranged between two bearing devices  18 , below the support shaft  11 . Without making contact, this magnet keeps the support shaft  11  in a position where it makes contact with the bearing devices  12 .  
         [0045]    With the exemplary embodiment shown herein, respectively only one magnet  13  is arranged between two bearing devices  18  and/or respectively only one bearing device  18  is arranged between two magnets.  
         [0046]    Longitudinal cutting devices  2  are shown respectively in FIGS. 5 and 6, for which the support  10  according to the invention is arranged in different ways in the intake area and the discharge area. With the cutting arrangement in FIG. 5, the supports  10  are arranged in the intake area and in the discharge area of the cutting arrangement, on the underside of the paper web  5 . The height of supports  10  is adjustable, depending on the edge-retention requirements. The support shafts  11  are thus adaptable and important, depending on the types of paper to be cut and the dimensions.  
         [0047]    Of course, it is also possible to arrange the supports  10  on both sides of the paper web  5 , as shown in FIG. 6.  
         [0048]    Owing to the fact that a support shaft  11  with a small diameter and bearing devices  18  are used, which position the support shaft  11  such that it can rotate, the bearing devices  18  are positioned outside of the axis of rotation for the support shaft  11 , and in particular, the axes of rotation of the respective bearing elements are parallel to but not co-linear with the axis of rotation of the support shaft  11 .  
         [0049]    The paper to be cut can thus be supported very close to the locations where the paper is cut in the longitudinal cutting device. As a result, the edge retention of the cut paper material is improved and longitudinal folds in the paper webs are furthermore avoided.  
         [0050]    The invention has been described in detail with respect to exemplary embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.