Abstract:
The invention relates to a cylinder, which is in contact with a material web. Said cylinder flexes in or against the direction of travel of the material web, in accordance with at least one pixel that is located on said web.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is the U.S. National Phase, under 35 USC 371, of PCT/DE 2003/004237, filed Dec. 22, 2003; published as WO 2004/085155 A1 on Oct. 7, 2004 and claiming priority to DE 103 13 444.1 filed Mar. 26, 2003, the disclosures of which are expressly incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention is directed to a cylinder, as well as to a device for guiding a web of material. The cylinder is bent with respect to the web travel direction in response to an image of the web. 
   BACKGROUND OF THE INVENTION 
   Pairs of cylinders are frequently employed as tools for guiding webs of material, or for processing their surfaces. The cylinders are rotatably arranged with pivotable shafts and delimit a gap through which the web of material runs. Along a clamping line which is parallel with the shafts, the web is subjected to a pressure from a cylinder, which pressure exerts a guiding pressure or effect on the web of material, or performs web processing. This pressure must be evenly distributed over the length of the clamping line to assure that the processing is even over the width of the web and, with guiding rollers, to prevent irregularities of any slippage occurring between the rollers and the web over the width of the web, which irregularities can lead to a deformation of the web per se. Such a deformation can be the source of indexing errors when printing on the web. 
   An important reason for the occurrence of irregularities in the print distribution along the clamping line is the inherent deformation of the rollers because of their own weight. It is known, for example, that the forme cylinders for rotogravure printing, in particular forme cylinders of a great width, of an order of magnitude between 1.5 m to 4 m, have a tendency to sag under their own weight. Because of this cylinder sag, the pressure along the clamping line between such a forme cylinder and a counter-pressure cylinder, which is arranged above it, is reduced toward the center of the paper web. For this reason, the counter-pressure cylinder of known rotogravure printing presses is also bent to match the outer shape of the counter-pressure cylinder to the bending of the forme cylinder, and to distribute the pressure between the two cylinders evenly over the clamping line. 
   A counter-pressure cylinder for a rotogravure press is known from DE 30 33 320 C2, and whose shell is received, rotatably seated, in rolling bearings in the area of its ends, in adjustable bearing end plates. An actuating member, which is supported on the associated adjustable bearing end plate, and which can be actuated in the radial direction with respect to the shaft, acts on the ends of the cylinder shaft, which shaft extends through the shell and protrudes from the shell. The shell of the counter-pressure cylinder is bent by operation of the actuating member, and the counter-pressure cylinder exterior shape is matched to the shape of a forme cylinder, which has been placed against it. 
   A counter-pressure cylinder, which cooperates with a forme cylinder in a rotogravure printing press, is also known from DE 100 23 205 A1. A variable matching of the counter-pressure cylinder to the forme cylinder is achieved with this counter-pressure cylinder. A linear drive mechanism, which is located at each of the ends of the counter-pressure cylinder, and between a fixed shaft and a rotating shell, acts, in a vertical radial direction, downwardly on an inner ring of a rolling bearing, while the center area of the shells is maintained rotatably, but not displaceably, on the shaft. 
   DE 88 08 352 U1 discloses a cylinder, whose bending can be adjusted in two planes. 
   U.S. Pat. No. 3,638,292 and EP 0 741 253 A2 show contact pressure rollers, which have wheels in their interior, and which can be charged with a pressure medium. These wheels are arranged on a common shaft. 
   U.S. Pat. Nos. 4,455,727 and 3,389,450 disclose rollers, which can be bent in two planes that are offset by 90°. Actuating elements are arranged in the interior of the rollers. 
   A cylinder with an assembly for generating an inner tension of the cylinder, and with a control unit/regulator for controlling the assembly, and with vibration sensors, is known from DE 199 63 945 C1. The assembly and actuating members are controlled in response to the vibrations detected by the vibration sensor. 
   A counter-pressure cylinder is also known from U.S. Pat. No. 4,913,051, which counter-pressure cylinder consists of a shaft and of a shell which can be rotated around the shaft. Inflatable chambers are provided between the shaft and the shell of this counter-pressure cylinder. The chambers will expand or extend, after being charged with pressure, and will thus cause bending of the shell. 
   EP 0 331 870 A2 discloses an arrangement for the seating of cylinders. Journals of a cylinder are seated in two bearings that are arranged side-by-side in the axial direction of the cylinder. The bearings can be individually moved perpendicularly with respect to the axis of rotation by the use of pressure medium cylinders in order to compensate for bending, for example. 
   An exact guidance of a web, in a manner which is free of indexing errors, is made difficult, particularly in connection with rotogravure printing presses of great width, because it is extremely difficult to produce forme cylinders, also of great length, and which have an exactly constant diameter over their length. In most cases, such a long forme cylinder is slightly thicker in its center than it is at its edges or ends. A traction force, which is exerted between the forme cylinder and a counter-pressure cylinder, on a web passed through between them, is therefore typically greater in the center of the web than it is at the edges of the web. 
   As a result of this uneven traction force, an uneven tension profile is generated within the paper web over its width. Since, in the course of the paper webs being processed in such a press, the paper webs absorb moisture, their stretching ability increases, so that an uneven stretching of the web, in accordance with the uneven tension profile, can occur. The result can be indexing errors. 
   Indexing errors between the center of the web, and an edge of the web, can be compensated for with the aid of an inlet roller, which is arranged staggered between two pressure gaps. However, in this case, it is disadvantageous that, on the other side of the paper web, the indexing errors become even greater, and that there is a danger of a lateral drift-off of the paper web. 
   The present invention creates a symmetrical tension profile in the web of material, which symmetrical tension profile increases toward either the center or toward the web edge areas and, in the areas of high tension, creates a change in web length, in the elastic range of the paper web. In this way, the invention provides the possibility of adjusting the image points of the different colors to be imprinted on the web, without letting the paper web drift off toward one side. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is directed to the provision of a cylinder, as well as to a device for guiding a web of material. 
   In accordance with the present invention, this object is attained by the provision of a cylinder, which is contacting a web of material, the cylinder having a bend either in, or opposite to the running direction of the web of material. The bend is imparted to the cylinder as a function of at least one image element on the web. The cylinder, and a second cylinder placed against it, can form a gap through which the web passes. The web is clamped along a clamping line defined by the cooperation of the two cylinders. That clamping line can be curved either in, or in opposition to, the web travel direction. 
   The advantages to be obtained by the present invention consist, in particular, in that the device makes it possible, in an easy manner, to make the effective path of the web of material, for example the effective path of a paper web, variable over the width of the paper web from a fixed point, such as from a guide roller that is located upstream of the gap, to a fixed point that is located downstream of the gap. The inhomogeneity of the web tension which results from this variability of the path length, can be set in such a way that it exactly compensates for an inhomogeneity caused by the thickening of the forme cylinder. In this way, the stretching of the web can be made uniform over its entire width. A printing of the web, which is free of indexing errors, becomes possible over the entire width of the paper web. 
   A cylinder shaft in accordance with the present invention preferably has a device, around which a first cylinder can be rotated, two end sections and a center section, which shaft and its sections support the first cylinder at its ends, or in the center. At least one actuating member is arranged on the shaft for shifting the end sections and the center section with respect to each other in a direction which is vertical with respect to the shaft of the first cylinder, and in this way to bend the first cylinder. If the displacement direction of the actuating member forms an angle with a plane defined by the shaft of the first cylinder and by the shaft of the second cylinder, the actuating member also can cause or effect the curvature of the clamping line, which is required by the present invention. 
   The actuating direction of this at least one actuating member is preferably rotatable around the shaft of the first cylinder. 
   It is also possible, in accordance with the present invention, to provide at least two actuating members, which shift the sections of the shaft, with respect to each other, in different directions. These different directions preferably form a right angle. A total displacement of the sections of the shaft in a direction, which forms an arbitrary angle with the plane of the cylinder shafts and which is a function of the amounts of the individual shifting, results from the superimposition of the shifting in these two directions. 
   The actuating direction of one of these two actuating members is preferably located in the plane of the shafts. 
   An end section projects, in a preferred manner, from each end of each of the first cylinders. At least one of the actuating members is arranged outside of the cylinder on at least one of these end sections. 
   With the aid of diametrically opposed actuating members, it is possible to cause a curvature of the clamping line. This curvature can be caused both with a center section which is deflected in the running direction of the web of material, as well as with a center section deflected against the running direction of the web of material. 
   At least one of the actuating members can be a set screw. 
   It is also possible to configure one of the actuating members as a hydraulic actuating member. 
   The device in accordance with the present invention advantageously contains at least one bearing, for example a rolling bearing, between the first cylinder and the shaft. 
   Also advantageously, the cylinder has a rubber surface. The resilience of the cylinder rubber surface makes it easier to set an even pressure distribution along the clamping line. 
   In an advantageous manner, in accordance with the present invention, the actuating members are in contact with a circulating device for a coolant or a lubricant. In this case, at least one seal element should be provided at the actuating members. 
   The second cylinder preferably is a forme cylinder. 
   In a particularly preferred manner, the device is a part of a rotogravure printing press. 
   A length of the first cylinder of the present invention is quite particularly preferred to lie between 1.5 m and 4 m, so that webs of material of a corresponding width can be processed with the device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail below. 
     Shown are in: 
       FIG. 1 , a side elevation view of a printing group of a rotogravure printing press in a schematic representation, in 
       FIG. 2 , a schematic front elevation view of the cylinders of the printing group and depicting an exaggerated cylinder bending, in 
       FIG. 3 , a side elevation view of a printing group, in 
       FIG. 4 , a longitudinal cross-sectional view through a counter-pressure cylinder, in 
       FIG. 5 , a first perspective representation of a bearing of the counter-pressure cylinder, in 
       FIG. 6 , a second perspective representation of a bearing of the counter-pressure cylinder, in 
       FIG. 7 , a view, taken along a section line A-A through the bearing represented in  FIG. 5 , in 
       FIG. 8 , a side elevation view of a printing group from  FIG. 3 , in 
       FIG. 9 , a side elevation view with a modification of the printing group, in 
       FIG. 10 , a longitudinal sectional view through an alternative counter-pressure cylinder, in 
       FIG. 11 , a further longitudinal sectional view through an alternative counter-pressure cylinder, in 
       FIG. 12 , a schematic longitudinal sectional view through the alternative counter-pressure cylinder in a view from above, in 
       FIG. 13 , an actuating member in a perspective representation, in 
       FIG. 14 , an enlarged portion of the longitudinal sections represented in  FIGS. 10 and 11 , in 
       FIG. 15 , a cross-sectional view through the counter-pressure cylinder at the level of an actuating member, in 
       FIG. 16 , a depiction of the effects of different degrees of bending on a web of material having image elements, and in 
       FIG. 17 , a schematic representation of a roller with a curvature in the running direction of a web of material. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A printing group, which is generally known per se, of a rotogravure printing press, is schematically represented in a side elevation view in  FIG. 1 . This generally known group consists of a first cylinder  06  and a second cylinder  02 , which define a cylinder gap  07 , through which a paper web  04  to be imprinted is conducted as the web  04  of material is clamped along a clamping line  08  which clamping line  08  extends perpendicularly with respect to the plane of  FIG. 1 . The second cylinder  02  is preferably provided with an engraved copper surface. The second cylinder  02  is a forme cylinder  02 , which can be easily disassembled, and which is dipped into an ink reservoir  01 . Forme cylinder  02  is seated, in a manner not specifically represented, but which is known per se, in a frame, that is not specifically represented in  FIG. 1 , and is connected with a drive mechanism. A doctor blade  03  for use in removing excess ink, which may be taken along by the forme cylinder  02  from the ink reservoir  01 , has been placed against the forme cylinder  02 . The first cylinder  06  is a counter-pressure cylinder  06 . It is maintained pressed against the forme cylinder  02  and is rotatably driven by the forme cylinder  02  by friction. Because of the effect of the contact pressure exerted by the counter-pressure cylinder  06 , as represented by an arrow in  FIG. 1 , and because of the effect of its own weight, the forme cylinder  02  sags in the center, as shown, in an exaggerated manner, in the elevation view of  FIG. 2  and in the lateral view of  FIG. 3 . In order to exert a uniform pressure over the entire length of the clamping line  08 , from one end of the cylinders  02  and  06  to the other, the counter-pressure cylinder  06  must follow the bending of the forme cylinder  02 , which bending can be further seen in  FIG. 2 . 
   The counter-pressure cylinder  06  is shown in a longitudinal, cross-sectional view in  FIG. 4 . Counter-pressure cylinder  06  is rotatable around a shaft  09  and has a hollow-cylindrical shell  11 . The shell  11  typically has a rubber-covered surface. The shaft  09  is comprised of two opposite shaft end sections  15  and a shaft center section  13 . Each one of two hollow journals  12  is connected with the shell  11 , is fixed against relative rotation with respect to shell  11 , and is rotatably maintained in a frame of the rotogravure printing press, which is not specifically show, by the use of suitable bearings, for example rolling bearings. The shaft center section  13  is extended, via its shaft end sections  15 , through the hollow journals  12 . Shaft center section  13  supports the center area of the shell  11  via one or several bearings  14 , which bearings  14  may be, for example, rolling bearings  14 , that are added between shaft center section  13  and the shell  11 . 
   A bearing bushing  16 , which is mounted on both sides of the counter-pressure cylinder  06  on the frame, and which is adapted to receive the journals  12 , is shown in a perspective representation in  FIGS. 5 and 6 , and is shown in  FIG. 7  in a sectional view that is taken along the line A-A from  FIG. 5 . The bearing bushing  16  has a recess  17 , which recess  17  receives a rolling bearing that is supporting a journal  12 , in an area of recess  17  having a large diameter and facing the counter-pressure cylinder  06 . In a narrower area, facing away from the counter-pressure cylinder  06 , recess  17  in bearing bushing  16  is used for receiving an end section  15  of the center section  13  of the shaft  09 , which narrower area of recess  17  can be seen in  FIG. 6 . Two connectors  18  are used as inflow or outflow connectors for a coolant or for a lubricant, which flows through the counter-pressure cylinder  06  in a circuit along an intermediate space between the center section  13  of the shaft  06  on the one side, and the shell  11  and the journals  12  of the shaft  06  on the other side. The coolant or lubricant is typically a thermal oil which, on the one hand, is used for lubricating the counter-pressure cylinder  06  and, on the other hand, is also used to remove heat which is generated in the course of the operation of the counter-pressure cylinder  06  because of flexing action, and which heat removal aids in the cooling of the counter-pressure cylinder  06 . 
   A tappet  19 , which is acting as an actuating member  19 , and which is preferably provided in the form of a brass bolt  19 , is also provided at the bearing bushing  16  which, hydraulically displaceable, is pressed against the end sections  15  of the shaft&#39;s center section  13  which are received in the narrower area of the bearing bushing  16 . Next to the tappet  19 , two set screws  21 , which are arranged diametrically opposite to each other with respect to a center axis of the shaft  09 , are provided in the bearing bushing  16  and also act as actuating members. A horizontal force is respectively exerted by each of the set screws  21  on the shaft end sections  13 . The tappet  19 , as well as the two set screws  21 , are all provided with sealing elements  22  at the level of a bore in the wall of the bearing bushing  16  into which they have been inserted. These sealing elements are provided to prevent the escape of the thermal oil from the bearing bushing  16 . 
   For adapting the counter-pressure cylinder  06  to an exterior shape of the bent forme cylinder  02 , the tappet  19  exerts a pressure force on the end section  15  of shaft  09  and in this way exerts a vertically directed force on the center section  13  of shaft  09 . This actuating force is transmitted, via the rolling bearings  14 , to the cylinder shell  11 , which, because of this force, can be caused to rest against the sagging forme cylinder  02 . The rolling bearings  14  assure that the cylinder shell  11  remains easily rotatable in spite of the considerable pressure and deformation forces. Bearings  14  are preferably configured as cylinder rolling bearings  14  in order to prevent the shell  11  from tilting against the center section  13 , which would negatively affect the rotatability of shell  11 . In this case, it can be seen that the radial play between the shaft center section  13  and the cylinder-shaped shell  11 , i.e. the width of the intermediate space, through which the oil flows, is dimensioned in such a way that, in case of a possibly occurring sagging of the shaft center section  13 , because of a force exerted by the action of the tappet  19 , no sliding contact between the center section and the shell  11  occurs at any point. In actual use, the distance of this intermediate space is only a few millimeters. 
   Since the shaft center section  13  only needs to transfer the force supplied by the tappet  19  to the shell  11 , a rolling bearing  14 , which is arranged in the area of the center of the shell  11 , is sufficient. In the preferred embodiment shown in  FIG. 4 , two rolling bearings  14 , which are arranged symmetrically with respect to the shell center, have been provided, and whose mutual spacing distance corresponds to approximately one third of the useful length the shell  11 . This makes it possible for the shell  11  to yield a little to a pressure of the forme cylinder  02  in its center area located between the rolling bearings  14 . 
   In addition to the vertical bending of the shell  11  caused by the tappet  19 , a horizontal bending of the shell  11  in the running direction or counter to the running direction of the paper web  04  is caused by utilization of the set screws  21 . This additional, horizontal bending is usable for compensating for registration errors, which often occur in the course of a printing forme being applied to the circumference of the forme cylinder  02 . 
   As represented in  FIG. 16 , several image elements are imprinted on a web of material. Preferably, several first image elements have been imprinted in the axial direction side-by-side in a first printing group, and corresponding second image elements have been imprinted in a second printing group. The depicted cylinder  06 , in particular the counter-pressure cylinder  06 , is a part of the second printing group. By proper bending of the counter-pressure cylinder  06  in the running direction of the web, or opposite to the running direction of the web of material, the image elements of the second printing group can be displaced in relation to the image elements from the first printing group, either opposite to, or in the web running direction. 
   The position of the center image elements is changed, in relation to the position of the two outer image elements in response to the bending of the cylinder  06 . In another example, which is not specically represented, the web of material has at least four groups of image elements, each of which is imprinted by one printing group. 
     FIG. 8  shows the effects of the superimposition of a vertical force, as exerted by the tappet  19 , and of a horizontal force, as exerted by the set screws  21 , respectively, as represented in  FIG. 8  by arrows identified by  19  or  21 , on the end section  15  of the shaft  09 . By accomplishing a bending of the shell  11  in the running direction of the paper web  04 , a curvature of the clamping line  08 , also in the running direction of the paper web  04 , takes place. In effect, a shifting of the center area of the shell  11 , with respect to the end sections of the shell  11 , occurs in a direction which forms an angle with a plane that is extending through the axes of the forme cylinder  02  and the shaft  09 , or the shell  11 . A corresponding curvature of the clamping line  08  is the result of this. 
   The forces exerted by the tappet  19  and by the set screw  21 , in the horizontal direction or in the vertical direction respectively, as seen in  FIG. 8  can, of course, be replaced by their resultant. It is also possible to replace the vertical actuating members  19  and the horizontal actuating members  21  with a single actuating member  19 , thus causing a shifting in the direction of the resultant, as shown in  FIG. 9 . For this purpose, the bearing bushing  16  can be mounted on the frame, for example, so that it is rotatable around the axis of the counter-pressure cylinder  06 . 
   In this embodiment, the set screws  21  can be omitted, and the deformation of the counter-pressure cylinder  06  can be realized with only the aid of the tappet  19 , whose direction of force application can now be changed by rotation of the bearing bushing  16 . 
   A longitudinal sectional view through a second preferred embodiment of a cylinder  23 , namely a counter-pressure cylinder  23 , from the side, is shown in  FIG. 10 , and a longitudinal sectional view through the counter-pressure cylinder  23 , in a view from above, is shown in  FIG. 11 . The counter-pressure cylinder  23  is comprised substantially of a hollow shaft  24 , a shell  26 , which is rotatably supported at its ends by the use of bearings, for example by the use of rolling bearings, on the shaft  24 , as well as by elements  27 ,  28 ,  29  for use in creating an inner tension in the counter-pressure cylinder  23 . The elements  27 ,  28 ,  29  which are embodied as actuating members  27 ,  28 ,  29 , have been introduced into the interior of the hollow shaft  24  and act, via a ring-shaped or annular gap between the shaft  24  and the shell  26 , on the shell  26 . The shell  26  is provided with an exterior rubber layer. Journals of the shaft  24 , which journals extend past the shell  26  in the axial direction, are seated in a frame, which is not specifically represented, of a rotogravure printing press, in bearings  43 ,  44 , which may be, for example rolling bearings  43 ,  44 . Each rolling bearing  43  is configured as a spherical roller bearing  43  for preventing the tilting of the shaft  24  in the sagging state. 
   A differentiation of the axially spaced actuating members  27 ,  28 ,  29  is made between first actuating members  27 , as well as second actuating members  28 ,  29 . The side longitudinal cross-sectional view in  FIG. 10  extends through the counter-pressure cylinder  23  in such a way that it intersects the first actuating members  27 , while the top plan longitudinal cross-sectional view represented beneath  FIG. 10  in  FIG. 11  extends through the counter-pressure cylinder  23  in such a way, that it intersects the second actuating members  28 ,  29 . The actuating members  27 ,  28 ,  29  are structurally identical and only differ only in their orientation in the hollow shaft  24 . The first actuating members  27  are all arranged in a first plane and are all aligned in the same first direction, the second actuating members  28 ,  29  are arranged in a second plane, which is orthogonal with respect to the first plane. However the actuating members  28  are each aligned in the second plane opposite to the actuating members  29 . 
   A longitudinal cross-sectional view through the second preferred counter-pressure cylinder  23  is shown, in a simplified way, as a schematic basic sketch in  FIG. 12 . As can be seen in this representation, the counter-pressure cylinder  23  also includes a vibration sensor  46  and a control unit  47 , which control unit  47  is in contact with the vibration sensor  46  and which control unit  47  controls the several actuating members  27 , shown by way of example, via a hydraulic connection. 
     FIG. 13  shows a perspective representation of one of the actuating members  27 ,  28 ,  29 . In  FIG. 14 , the arrangement of such an actuating member  27 ,  28 ,  29  in the counter-pressure cylinder  23  can be seen, in the form of an enlarged portion of a longitudinal cross-sectional view through the counter-pressure cylinder  23 . Finally,  FIG. 15  shows a cross-sectional view of the actuating member  27 ,  28 ,  29  arranged in the counter-pressure cylinder  23  and taken along the line C-C shown in  FIG. 14 . 
   The actuating members  27 ,  28 ,  29  each have an angular shaft  31 , with a flange  32  formed on it, each of which actuating member  27 ,  28 ,  29  each has been inserted, with little play and with the interposition of a seal  33  between the flange  32  and the shaft  24 , into a window or aperture of the shaft  24 , as seen in  FIG. 14 . The angular shape of the shaft  31  acts as a twist prevention mechanism for each of the actuators  27 ,  28 ,  29 . A pressure cylinder  34  has been inserted into the shaft  31 , and in whose chamber a piston  36  can be shifted by the action of hydraulic fluid supplied via a hydraulic connector  37 . The hydraulic connector  37  is mounted in one of two bores  48  of the hydraulic cylinder, which both terminate in the piston receiving chamber. In actual use, the second bore  48 , which is shown unoccupied in  FIG. 15 , is provided with a blind plug or with a second hydraulic connector  37 , from which a pipe line leads to an adjoining actuating member  27 ,  28 , or  29 . In this way, the actuating members  27 ,  28 ,  29 , can be combined into several groups of interconnected actuating members, which actuating members in each group are charged with an identical pressure, which actuating pressure can be independently controlled from group to group. 
   Each one of the actuating members  27 ,  28 ,  29  has been combined, with wheels  38 , into a module, each which module can be removed as a unit. 
   In the embodiment represented in  FIGS. 13-15 , the piston  36  has two wheels  38 , which wheels  38  can be rotated around a common wheel shaft  35  and which together constitute a double roller which is acting as a rolling bearing, which wheels  38 , with the piston  36  extended, roll off on a bearing race  39  that is introduced between the shell  26  and the shaft  24 , as seen in  FIGS. 14 and 15 . The wheel shaft  35  is connected with the actuating member  27 ,  28 ,  29  via a joint  40 , which is embodied as an adjusting bearing  40 , for example. Each actuating member  27 ,  28 ,  29  has its own, independently movable shaft  35 . These shafts  35  are not connected with each other. In the present example, the shaft  35  supports two wheels  38  seated on rolling bearings. In all of the preferred embodiments, the circumference of the wheels lies completely radially outside of the axis of rotation of the shell  26 . 
   When the actuating members, such as actuating members  27 , are charged with pressure, they cause a bending of the center area of the hollow shell  26  of the counter-pressure cylinder  23  downward in  FIG. 10 , or transversely in respect to the plane of  FIG. 11 . By charging the actuating members  28  or  29  with pressure, it is possible to obtain bending of the shell  26  selectively toward the top or toward the bottom in  FIG. 11  or, with simultaneous charging of the actuating members  27 , and the members  28  or  29  in a direction obliquely oriented with respect to the planes of intersection of  FIGS. 10 and 11 . It is also possible to simultaneously charge the oppositely oriented actuating member  27 ,  28 , which opposing actuation does not necessarily lead to bending of the shell  26 , but instead leads to a distortion of its cross section into an ellipse. 
   As can be seen in  FIGS. 10 and 11 , the shaft  24  has inlets or outlets  41  for a thermal oil on both sides, which thermal oil is used as a coolant or as a lubricant for the counter-pressure cylinder  23 . Here, the thermal oil flows through lines  42  in the ring-shaped gap between the shell  26  and the shaft  24 . It flows through the counter-pressure cylinder  23  in this gap over the cylinder&#39;s entire length and leaves it via corresponding lines  42  and inlets or outlets  41  at its opposite side. The wheels  38  of the actuating members  27 ,  28 ,  29  are lubricated in this way, and the thermal oil also removes frictional heat, which heat is generated as a result of flexing action of the shell  26  occurring on an outer rubber layer of the shell  26 , as well as on account of friction. 
   During operation of the rotogravure printing press, the hollow shell  26  of the counter-pressure cylinder  23  rotates around the fixed shaft  24 . For generating a uniform pressure over a length of the clamping line  08 , between the counter-pressure cylinder  23  and the forme cylinder  02 , it is necessary to match the shape of the counter-pressure cylinder  23  to an outer shape of the forme cylinder  02 . This is done by use of the actuating members  27 ,  28 ,  29 . By charging members  27 ,  28 ,  29  with hydraulic pressure, the pistons  36  are extended and the wheels  38  are caused to press against the hollow cylinder shell  26 , which wheel pressure results in a shifting of the hollow shell  26  with respect to the shaft  24 . The outer shape of the shell  26  can thus be adapted to compensate for bending or for other irregularities in the shape of the forme cylinder  02 , and the desired pressure distribution in the clamping lines  08  can be realized. Above all, the right-angled arrangement of the first actuating members  27  and of the second actuating members  28 ,  29  permits bending of the shell  26  at any arbitrary angle, with respect to a plane extending through the axes of the counter-pressure cylinder  23  and the forme cylinder  02  placed against it, and therefore permits the setting of a path length of the web, which is variable in the direction of the width of the web  04 , between two fixed points, such as for example between guide rollers situated on both sides of the gap  07 . 
   As previously mentioned, during operation of the counter-pressure cylinder  23 , the shell  26  rotates around the shaft  24 . In the course of this relative rotation, vibrations of the counter-pressure cylinder  23  occur, which vibrations can build up to greater amounts if the rotation frequency of the shell  26 , or if a whole number multiple thereof, corresponds to a resonance frequency of the counter-pressure cylinder  23 . The strength of these vibrations is measured by the vibration sensor  46 , and the result of the measurement is transmitted to the control unit  47 . If the control unit  47  notes an increase of the strength of the vibrations, past a predetermined threshold value, which increase in strength indicates the presence of a resonance, control unit  47  hydraulically triggers the actuating members  27 ,  28 ,  29 . When these actuating members  27 ,  28 ,  29  push against the shell  26 , they cause bending of the shell  26  and, to a reduced amount, they also cause bending of the shaft  24 . Corresponding to the hydraulic pressure supplied by the control unit  47 , a contact pressure, with which respective pistons  36  of each actuating member  27 ,  28 ,  29  press against the shell  26 , varies, and along with the variance in contact pressure, the inner tension of the shell  26  and of the shaft  24  varies. An increase of the pressure corresponds to a stiffening the counter-pressure cylinder  23 , and therefore to an increase in its resonance frequency. If, by changing the contact pressure, the resonance frequency is changed to such an extent that it no longer agrees with the frequency of rotation of the shell  26 , the undesired vibrations are reduced. 
   While preferred embodiments of a cylinder and device for guiding a material web, in accordance with the present invention, have been set forth fully and completely hereinabove, it will be obvious to one of skill in the art that various changes in for example, the specific structure of the forme cylinder, the source of the hydraulic fluid and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the appended claims.