Abstract:
Blankets, which are mounted or dismounted on cylinders and rollers, are fitted to these cylinder in a homogenous manner to insure their proper winding and unwinding. Several pressure or force application rollers, that each can move independently, can be fitted to the cylinder simultaneously to provide a device for pressing the blanket onto the cylinder. Different rollers for mounting or for dismounting the blanket can be provided.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to devices for pressing a packing or covering or dressing, such as a forme or a blanket on a cylinder. A plurality of rollers are used to either install or to remove a dressing. A single or shared adjusting mechanism is provided to move the rollers. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 3,828,672 A discloses a device for pressing a printing plate against a plate cylinder. For installation and removal of the printing plate, a roller, which extends parallel to the cylinder axis and which also extends over the entire plate width, is pivoted toward the cylinder by the use of two arms and is pressed against the plate cylinder by a hydraulic working cylinder. 
     EP 07 12 725 B1 discloses a device that is usable for pressing against printing plates with the aid of a number of rollers which are disposed along the cylinder circumference, and which do not extend over the entire plate width or the cylinder length. These rollers are placed individually or in pairs against the plate cylinder by the use of a piston rod of a working cylinder. The device has two such roller systems that are disposed next to each other and that are in engagement with each other. Each system is comprised of several rollers and associated working cylinders. The first system is used, for example for installing a new printing plate, and the second system is used for removing a dirty printing plate. In order to protect the apparatus from getting dirty, opening flaps are provided in the movement region of the rollers and can be actuated by the provision of separate working cylinders. 
     EP 04 33 798 B1 has a pivotable guard for a changing device of a printing plate which pivotable guard protects the entire apparatus that is oriented toward the access side from getting dirty. The pressing roller is a one piece roller, and working cylinders situated at both ends of the roller place it against the cylinder by use of a lever. In a similar manner, in EP 04 35 413 A2, a number of rollers, which are disposed on an axle, are placed against the cylinder as a group by the use of a two-arm lever which is driven by a working cylinder in order to guide the plate end into the cylinder channel during plate installation. 
     U.S. Pat. No. 4,727,807 A shows a device for installing and removing printing plates from plate cylinders by the use of a pivotable gripping arm. A number of rollers, which are spaced apart from each other in the circumference direction of the cylinder and which are situated next to each other in the longitudinal direction of the cylinder, are placed against the cylinder both for installing and removing the plate. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to produce devices for pressing on a dressing, packing or cover to place the dressing, packing or cover on a surface of a cylinder or to remove the dressing, packing or cover from the surface of the cylinder. 
     The object is attained according to the present invention by the use of a number of rollers that can be placed against the surface of the cylinder. At least two rollers are supported independently of each other and can each be placed against the cylinder by a single adjusting mechanism. At least one roller is used during dressing, packing or cover installation and the other is used during dressing, packing or cover removal. The rollers are positioned one after the other in a circumferential direction of the cylinder. Both are driven by a shared adjusting mechanism. 
     The advantages that can be attained with the present invention are comprised particularly in that a number of rollers, which can move independently of one another, are actuated by a single mechanism and are selectively pressed against the cylinder. Each roller is actuated directly and with the same force. The force can be adjusted easily by the use of a uniform pressure level. This assures a uniform pressure of a dressing, packing or cover on a cylinder. The rollers are supported at least partially independently of one another, which independent support permits a mutually independent movement of the rollers at least in the direction toward the cylinder. 
     The present invention is not sensitive to deviations in the position of the device in relation to the cylinder and in relation to a deflection. This allows for a simple and a compact design, which, for statics-related reasons, is only possible at a greater expense when a single roller is provided that extends continuously over a plate or over the width of a cylinder. 
     It is also particularly advantageous that despite the direct deployment of each of the individual rollers, only a single adjusting mechanism is required for a group of rollers. This results in considerable savings with regard to drive technology and with regard to regulating and control costs. 
     The stroke of the adjusting mechanism can be easily increased as needed for each roller by the use of a stroke multiplication linkage so that, for example, the device can be disposed in a stationary fashion and does not have to be moved as a whole in relation to the cylinder. 
     In a simple manner, the device for pressing a dressing, packing or cover on a cylinder in accordance with the present invention can also be embodied so that for the installation and for the removal of dressing, packing or cover, different respective rollers are placed against the cylinder. This has the advantage that during blanket or plate changing, new blankets or plates to be installed on the cylinder do not get smudged by already dirty rollers that were used for the removal of prior blankets or plates. In an advantageous embodiment, the rollers for installing the dressings, packings or covers, typically in the form of blankets or plates and the rollers for removing them are disposed so that they can be pivoted around an axis, which permits a continuous placement of rollers over the entire width of the blanket or plate or permits the blanket or plate to be pressed against the cylinder at the same respective location. 
     Flaps, that move synchronously with the rollers, are used to guard the rollers against the possibility of getting dirty when they are in a retracted position. It is particularly advantageous to couple the movable guards to the roller supports that are moved by the adjusting mechanism. When the rollers are deployed, the guards open at the same time, which opening of the flaps or guards involves no further control and drive expense. 
     For an exact insertion of a leading end of a dressing, packing or cover, such as a blanket or plate, at least one stop is advantageously provided, which is stationary in relation to the machine stand. It is advantageous that when installing the clover, the formation of the stop imparts an initial stress on the leading end, which permits the cover to engage in detent fashion in the provided clamping or tensioning device in a manner that is reproducible because it is guided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention are shown in the drawings and will be described in detail below. 
     FIG. 1 is a partial perspective view of a first preferred embodiment of a device for pressing against the dressing, packing or cover in accordance with the present invention and showing the device in the deployed position A; 
     FIG. 2 is a cross-sectional view through a second preferred embodiment of the present invention, and using first and second rollers for installation and removal of the dressing, packing or cover; 
     FIG. 3 is a cross-sectional view through a third preferred embodiment of the present invention, and using first and second rollers for installation and removal of the dressing, packing or cover; 
     FIG. 4 is a cross-sectional view through a fourth preferred embodiment of the present invention, and with an increased stroke of the roller movement, pivoting guards for covering the rollers, and a stop for the secure insertion of the leading plate end; and 
     FIG. 5 is a cross-sectional view, similar to FIG.  2  and showing a single adjusting mechanism. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A cylinder  01 , for example a forme cylinder or a transfer cylinder  01  of a rotary printing press, has a dressing, packing or cover  02 , for example a printing plate or forme  02  or a rubber blanket  02 , disposed on it during operation, as may be seen in FIG.  1 . For ease of description, this dressing, packing or cover  02  will be referred to hereinafter as cover  02 . 
     The device for pressing the cover  02  against the cylinder  01  is advantageously disposed so that it is stationary in relation to the cylinder  01 , and only cooperates with the cylinder  01  when actuated. In order to install the cover  02  onto the cylinder  01  or in order to remove the cover, a device for pressing against the cover  02  similar to the one depicted in FIG. 1 can also be pivoted against the cylinder  01  by the use of a device that is not described in detail here. This can, for example, be achieved by the use of pivotable lever arms, through linear motion against a threaded spindle, or with other linear drive mechanisms. 
     When the device for pressing against a cover  02  is in the operational state, as depicted in FIG. 1, i.e. when changing the cover  02 , the device extends with its longitudinal direction approximately parallel to an axis of rotation of the cylinder  01 . During installation or removal of the cover  02 , a number of rollers  03 , which are associated with the pressing device, are pressed against the rotating cylinder  01  by the operation of an adjusting mechanism, generally at  04 . 
     The cover pressing device essentially has a number of rollers  03  which are spaced apart from one another in the longitudinal direction of the cylinder  01 , roller supports  06  that support the rollers  03 , the adjusting mechanism  04 , a support surface  07 , and possibly a frame  08 . For example, the frame  08  can be disposed, in a stationary or mobile fashion, on a machine side frame that is not specifically shown. For example, the adjusting mechanism  04  is embodied as a reversibly deformable hollow body  04 , such as, for example a hose  04 , which can be acted on with pressure fluid. The frame  08  serves to contain the roller supports  06  and the hollow body  04  and can include the support surface  07 . When acted on by pressure fluid, the hollow body  04  is caused to expand against the support surface  07  and places the roller  03  against the cylinder  01  by engageable with a surface  09  of the roller support  06  that cooperates with the deformable hollow body  04 . 
     In a first preferred embodiment of the device for pressing a cover  02  against a cylinder in accordance with the present invention, the frame  08  is disposed approximately parallel to the rotation axis of the cylinder  01  in the longitudinal direction of the cylinder  01  and is configured as an approximately U-shaped crossbar  08  that has a base  13  and depending legs  11 ;  12  on opposite sides of the base  13 . Between the legs  11 ;  12 , and oriented away from the base  13 , there is a strip  14 . A number of guides  16  extend through the strip  14 , which guides  16  are spaced apart from one another in the longitudinal direction of the cylinder  01 . For example, each guide  16  in the strip  14  is configured as a bore or as a bore containing a sleeve or a bearing bushing and allows a strut, rod or tappet  17 , that is associated with or a part of the roller support  06  to move in a longitudinally guided fashion. 
     The strip  14 , together with the two depending legs  11 ;  12 , and the base  13 , form a hollow chamber  18  that is extending in the longitudinal direction of the cylinder  01 . On its side oriented toward the hollow chamber  18 , the base  13  of the U-shaped cross bar has the support surface  07  that, as discussed above, cooperates with the inflatable hollow body  04 . The legs  11 ;  12  can also be embodied as struts or can be omitted entirely. 
     The inflatable or expandable hollow body  04  is disposed in the longitudinal direction in the hollow chamber  18  between the two legs  11 ;  12 , the base  13  with the support surface  07 , and the surfaces  09  of the roller supports  06  that cooperate with the hollow body  04 . 
     The roller support  06 , which is embodied with two arms, essentially has a head  19  which is embodied, for example as a plate  19 , and which plate  19  is disposed in the hollow chamber  18  of the frame  08 , and cooperates with the hollow body  04 . Roller support  16  also has two struts, rods, or tappets  17  that each protrude through a respective guide  16  of the strip  14  and are each provided with a foot  21 , which supports the roller  03 . The strut  17 , which may be, for example a cylindrical rod  17 , is disposed so that it can slide in respect to its longitudinal direction in the guide  16  of the strip  14 . Rod  17  connects the other components of the roller support  06  at its respective ends, namely connecting the plate  19  disposed in the hollow chamber  18  to the foot  21 , which is disposed outside the hollow chamber  18 , which foot  21  supports the roller  03 , and which is embodied, for example, in the form of a leg  21 . The cross section of the rod  17  approximately corresponds to the cross section of the guide  16  and/or to the inner diameter of a bearing bushing or a sleeve provided in the guide  16  for better axial guidance of the rod  17 . 
     On at least one of its side surfaces  22 , the leg  21  has a radial bearing  23 , for example a bearing bushing  23  for use in containing an axle  24  that is associated with the roller  03 . The roller  03  is disposed between the two legs  21  so that its longitudinal axis extends approximately parallel to the rotation axis of the cylinder  01  during a cover plate change, 
     At each of its ends, the roller  03  has an end of the axle  24 , which axle  24  either passes all the way through the roller  03  or is discontinuous. These axle ends each cooperate with an associated bearing bushing  23  in their associated leg  21 . The roller  03  can be a rubber roller, a plastic roller, or a different roller  03  whose running surface is provided with a soft covering that does not damage the cover  02 . 
     On its side oriented toward the hollow body  04 , the roller support head or plate  19  has the first surface  09  that cooperates with the deformable hollow body  04 . A second surface  26  of the plate  19 , opposite from the first surface  09 , cooperates as a stop  26  with the surface  27  of the strip  14  which is oriented toward the hollow chamber  18 . It is advantageous to dispose at least one flexible element  28 , such as, for example a spring  28 , between the surface  27  of the strip  14  and the surface  26  of the roller support head or plate  19 . This is achieved, for example, by the spring  28  either encompassing the rod  17  or being inserted into recesses in the plate  19  and the strip  14 . 
     The roller support  06  can also be embodied as being one-armed, wherein each rod or tappet  17  is associated with an individual plate  19  that is disposed in the hollow chamber  18 . In this embodiment, two roller supports  06 , each respectively disposed in the guide  16 , cooperate to support the roller  03 . The plate  19 , rod  17 , and legs  21  can also be embodied of one piece with one another, wherein the roller support  06 , at the end protruding into the hollow chamber  18 , i.e. the head  19 , advantageously has an enlarged cross section or at least a stop  26 , and at least on an end protruding from the strip  14 , such as the foot  21 , has a bearing bushing  23 . 
     The head  19  of the roller support  06  can also be embodied as a plate  19 , which extends over several rollers  03  and on which the rods  17  and feet  21  for several rollers  03  are disposed. However, in this instance, it is advantageous if the head  19  of the roller support  06  is embodied being as reversibly deformable, for example in the form of a sheet metal strip. 
     In each embodiment of the device for pressing a cover against a cylinder, the roller supports  06  and rollers  03  are disposed on the strip  14  so that the rollers  03  that are spaced apart from each other in the longitudinal direction are each supported so that they can each rotate around an axis of rotation which is extending approximately parallel to the rotation axis of the cylinder  01  when the device for pressing against the cylinder  01  is pivoted. 
     The rollers  03  are advantageously supported so that they can move individually and independently of one another. A number of individually supported rollers  03  can be actuated by a single adjusting mechanism  04 . It is also possible to provide several groups of rollers  03 , which can move independently of one another and which can all be actuated by the use of a single adjusting mechanism  04 . 
     The device for pressing a cover  02  against a cylinder  01 , and with a number of first rollers  03 , in accordance with the first preferred embodiment, as depicted in FIG. 1, functions as follows. In order to change the cover  02 , such as a printing plate or a blanket, the pressing device is pivoted against the cylinder  01  so that the rotational axis of the cylinder  01  and the axle  24  of the roller  03  extend approximately parallel to each other. In this position of the device, the deformable hollow body  04  is acted on by pressure fluid. When the hollow body  04  is acted on by pressure fluid and the resulting reversible shape change to the hollow body  04  occurs, the deformable hollow body  04  is supported against the support surface  07  and presses all of the roller supports  06  resting against the hollow body  04  with their support surfaces  09  simultaneously, counter to the force of the springs  28 , outward, and with the same pressure, against the cover  02 . The rollers  03  and roller supports  06  are now disposed in the deployed position “A”, as seen in FIG. 1. A slight deviation in the position of the device or an inclination of the cylinder  01  is compensated for by the pressure uniformly prevailing over the entire length of the hollow body  04  and the mutually independent support of the individual rollers  03 , by virtue of the fact that rollers  03 , which are spaced further apart from the cylinder  01 , are displaced further out from the hollow chamber  18 . All of the roller supports  06  are pushed out from the hollow chamber  18  until they come into contact with, and exert the same force against the cover  02 . However, the latter only occurs in the tolerance range established by the length of the rod  17  protruding into the hollow chamber  18 . 
     In another preferred embodiment of the present invention, in addition to the first rollers  03 , which are spaced apart from one another and which are placed against the cylinder  01  in order to install new covers  02  onto it, the device can also have a number of second rollers  29 , which are placed against the cover  02  in order to remove it. This second preferred embodiment of the present invention is depicted in FIG.  2 . 
     In the second embodiment of FIG. 2, with a number of first rollers  03  and a number of second rollers  29 , the widened U-shaped frame  08  contains a widened strip  14 , which has a row of second guides  31  in the longitudinal direction of the device, with these second guides  31  being parallel to the row of first guides  16 . The second roller supports  32 , with the second rollers  29 , which are disposed parallel to the first rollers  03 , are supported so that they can slide in these second guides  31 . A second adjusting mechanism  33  such as, for example a second deformable hollow body  33 , is disposed in the hollow chamber  18  between the support surface  07  and the surfaces  34  of the second roller supports  32  and is cooperating with the first deformable hollow body  04 . The first roller supports  06  and the second roller supports  32  can also be actuated by a single deformable hollow body  04  that would be correspondingly embodied and positioned in a manner similar to the first and second deformable bodies  04  and  33 , respectively. 
     In accordance with the second preferred embodiment, in order to change the cover  02 , first the second rollers  29  are placed against the cylinder  01 . This placement of second rollers  29  can be executed by acting on the deformable hollow body  33  with pressure fluid and additionally by pivoting the frame  08 , if need be, around a pivot axis ending in the longitudinal direction, for example about a shared pivot axis S, so that only the second rollers  29  are disposed in the deployed position A and cooperate with the cover  02 . After the old cover  02  is removed, a new cover  02  is then secured in place. The hollow body  04  is acted on with pressure fluid and the frame  08  is pivoted, if need be, in the opposite direction so that only the first rollers  03  cooperate with the new cover  02  and are disposed in the deployed position A. 
     If the first roller supports  06  and second roller supports  32  are actuated jointly by pressurization of a single deformable hollow body  04 , as depicted in FIG. 5, then the selection of the rollers  03  or  29  to be activated is executed exclusively by pivoting the frame  08  around the axis extending in the longitudinal direction, for example the pivot axis S. The uniform adjusting force exerted against the cylinder  01  or against a cover  02  on the cylinder  01  for a number of rollers  03  or  29  associated with one deformable hollow body  04  is exerted by acting on the one deformable hollow body  04  with pressure fluid. 
     In a third preferred embodiment of the present invention, as shown in FIG. 3, for the arrangement of a number of first rollers  03  and of second rollers  29 , the first rollers  03  and the second rollers  29  are situated approximately diametrically opposite from each other on the frame  08 . In contrast to the device described in conjunction with FIG. 1, in this third embodiment, the base  13  that borders the hollow chamber  18  is eliminated. Instead of the base  13 , a second strip  36  with second roller supports  32  and with the second rollers  29  is provided, which is mirror symmetrical to a plane, the plane of symmetry E 1 , and to the hollow body  04 . The second roller supports  32  have surfaces  34  that cooperate with the hollow body  04  and have a surface  37  that cooperates as a stop  37  with the second strip  36 . The legs  11 ;  12  can be elongated, thus assuring the device of being covered at the sides. The device for pressing a cover  02  against a cylinder  01 , as depicted in FIG. 3 can be pivoted by use of a device, which is not specifically shown, in relation to the longitudinally extending pivot axis S, which lies in the plane of symmetry E 1  and which extends parallel to the axles  24  of the first rollers  03  and to the axles  24  of the second rollers  29 . With a diametrical disposition of the rollers  03 ;  29 , the shared pivot axis S advantageously coincides with the line of the plane of symmetry E 1  and an intersecting plane E 2  extending through the axles  24  of the first rollers  03  and the second rollers  29 . 
     In order to change the cover  02  by use of the third preferred embodiment, initially the second rollers  29  are placed against the cylinder  01 . This is accomplished by pivoting the frame  08  around the longitudinally extending pivot axis S and then acting on the deformable hollow body  04  with a pressure fluid so that the second rollers  29  cooperate with the cover  02  and are disposed in the deployed position A. In this connection, the two roller supports  06 ;  32  for the rollers  03  and  29 , respectively are pushed apart from each other, for example until the stop  26  of the freely moving roller support  06  cooperates with the first strip  14 . In a manner that corresponds to the support surface  07  from the first preferred embodiment which is depicted in FIG. 1 , the surface  09  of the first roller support  06  cooperates with the hollow body  04  as a support surface  09 . When the deformable hollow body  04  relaxes, the roller support  32  is reset by the spring  28 . After the old cover  02  is removed and the new cover  02  is secured in place, the frame  08  is pivoted, for example by 180°, so that after the deformable hollow body  04  is again acted on with pressure fluid, the first rollers  03  cooperate with the new cover  02  and are disposed in the deployed position A. When the hollow body  04  is again acted on, the stop  37  cooperates with the second guide  36  and the surface  34  cooperates as a support surface  34  with the deformable hollow body  04 . 
     The first roller supports  06  and the second roller supports  32  can also be disposed at other angles α enclosed between the first rollers  03 , the hollow body  04 , and the second rollers  29 , as shown in FIG.  3 . The second and third preferred embodiments, as depicted in FIGS. 2 and 3, show the two extremes for a number of first rollers  03  and a number of second rollers  29  disposed next to one another in parallel (α=0°) and diametrically opposite one another in relation to the hollow body  04  (α=180°). 
     The fourth preferred embodiment of the present invention, as shown in FIG. 4, shows another device for pressing against the cover  02 , in which the stroke produced by the deformation of the deformable hollow body  04  is multiplied into an increased movement of the rollers  03 . 
     As seen in FIG. 4, the deformable hollow body  04  and several rollers  03  are disposed, extending longitudinally approximately parallel to the rotation axis of the cylinder  01 , in the frame  08 . The frame  08  is an approximately U-shaped crossbar  08  with a base  13  and legs  11 ;  12  disposed opposite each other. In an advantageous embodiment, the leg length l 12  of the leg  12  is embodied as longer than the length l 11  of the leg  11 . The leg  12  of the U-shaped crossbar  08  can open outward at its outer end. 
     The deformable hollow body  04  is disposed inside the U-shaped crossbar  08 , extending in its longitudinal direction, between the support surface  07  associated with the base  13 , the legs  11  and  12 , and the upper surfaces  09  of the heads  19  of the roller supports  06  cooperating with the hollow body  04 . 
     The roller support  06  essentially has the head  19 , which cooperates with the deformable hollow body  04 , and has at least one strut rod, or tappet  17  on which the roller support foot  21  is disposed and that respectively supports the roller  03 . The strut  17  is at least disposed with its head  19  positioned between the legs  11 ;  12  in the frame  08 . It is advantageous to provide one roller support  06  for each roller  03 , and with the roller support  06  having two struts  17 , each strut being provided with a foot  21  for supporting the roller  03 . 
     On its side oriented toward the hollow body  04 , the head  19  of the roller support  06  has the upper surface  09 , as discussed above, and approximately perpendicular to this upper surface  09 , the head  19  has two side surfaces  38 , with which the roller support head  19  of the roller support  06  is supported against the leg  11  and/or  12  of the frame  08  For example, the head  19  may be embodied as a plate  19 . The side surface  38  can also be the surfaces oriented toward the leg  11 ,  12  of several sliding feet  39  or supporting feet  39  that are disposed next to, and which are spaced apart from each other and are disposed on the plate  19 , on the sides oriented toward the legs  11 ;  12 . The strut, rod or tappet  17  connects the plate  19 , which is disposed at its first end, to the roller support foot  21  of the roller support  06 , which is disposed at its second end, and which supports the roller  03 . The plate  19  and the two struts  17  can also be embodied as being of one piece with one another. 
     In contrast to the roller support foot  21 , which is rigidly connected to the strut  17  in the first preferred embodiment, in the fourth preferred embodiment, the foot  21  of the roller support  06  is embodied as a rocker or as a one-armed lever  21 , which is actuated by movement of the strut  17  that functions as a tappet  17 . The lever  21  is supported so that it can rotate around a fulcrum  41  situated at a first end of the lever  21 . 
     The fulcrum  41  of the lever  21  is disposed on a rotation axis D, which extends approximately perpendicular to the longitudinal direction of the strut  17  and approximately parallel to the axle  24  of the rollers  03  and which is stationary in relation to the frame  08 . For example, this fulcrum  41  is embodied as a linkage comprised of a fork head  42  fastened to the frame leg  12  and a bolt  43  that passes through the fork head  42  and the lever  21 . 
     At a point that is spaced from the fulcrum  41 , the strut  17  engages the lever  21 . The lever  21  and strut  17  are connected to each other so that they can rotate around an axis which is approximately parallel to the axle  24  of the rollers  03 . This connection is made, for example, by the use of a bolt  44 , which is disposed in aligned bores in the lever  21  and in the strut  17 . 
     The bearing bushing  23  or a similar mechanism, which is suitable for supporting the roller  03 , is disposed at the second end of the lever  21  opposite from the fulcrum  41 . In an advantageous configuration, two levers  21  can be associated with a single roller support  06  to respectively support one roller  03 . The roller  03  is disposed between the two levers  21  so that its axle  24  extends approximately parallel to the axis of the cylinder  01  when the levers  21  are actuated by movement of the respective strut  17  of the roller support  06 . 
     The rollers  03  can also be placed against the cylinder  01  by use of two-armed levers and by differently structured or differently positioned linkage elements, wherein when acted on with pressure fluid, the deformable hollow body  04  actuates a drive element through its reversible deformation, and the stroke of the resulting linear movement on the drive element is translated, possibly by a corresponding coupling, into a movement of the rollers  03 . It is advantageous to provide such a transmission or a linkage, as described above, which multiplies the stroke of the linear movement generated in the push rod or tappet  17 , during deformation of the hollow body  04 , into a greater movement of the rollers  03 . 
     The resetting of the rollers  03  or of the roller support  06  is advantageously produced by a spring force. For example, a spring  28  acting on the lever  21  can be fastened to the frame  08  or the strut  17 . It is also possible to place a compression spring between the head  19  and a stop that is not shown. 
     In a preferred configuration of the present invention, when the device is not actuated, the U-shaped profile of the frame  08  is closed by the provision of one or more guards  47  which are disposed next to one another in the longitudinal direction of the frame  08 . 
     Each guard  47  is fastened to the shorter leg  11  of frame  08 , as seen in FIG. 4, and can pivot in relation to an axis extending in the longitudinal direction of the frame  08 , for example by the use of a hinge  48 , a strap hinge, or articulating joints. The guard  47  is configured so that it completes the frame  08  in the circumference direction on the shorter leg  11  and at the open end of the U-shaped cross section. When the leg lengths  11  and  112  are the same, the guard  47  only closes off the open end of the U-shaped frame  08 . 
     On the side oriented toward the inside of the frame  08 , the guard  47  has, for example, a coupler  49 , which is disposed, at a first end, on the guard  47  and at a second end, on the roller support  06 , and preferably on the strut  17 , so that coupler  49  can pivot around an axis approximately parallel to the longitudinal direction of the frame  08 . The pivoting connection of the coupler  49  to the guard  47  is embodied, for example, as a hinge joint with a link plate  51  and a bolt  52 , all as seen in FIG.  4 . The coupler  49  is fastened to the strut  17  for example by the use of a bolt  53 , which is received, in a form-fitting manner, in a bore  54  in the strut  17 . The guard  47  and the coupler  49  are disposed on the frame  08  or on the strut  17  so that when the roller support  06  is in the rest position, i.e. when the strut  17  is not slid toward the opening in the frame  08  by the pressurization of the deformable hollow body  04 , the guard  47  and the U-shaped frame  08  together encompass the rollers  03  and the adjusting mechanism. In other words they completely enclose the roller support  06  and the hollow body  04 . 
     The guard  47  can also be coupled to the roller support  06  by other linkage arrangements so that it is opened or closed simultaneously during deployment or retraction of the rollers  03  without incurring additional drive or control costs. It is also possible to provide a parallel arrangement of a number of deformable hollow bodies  04  next to each other in the longitudinal direction of the cylinder  01  or one after or beside the other, in the circumference direction of the cylinder  01 , for example in order to actuate first or second rollers  03 ;  29  in a manner that corresponds to the apparatus according to the second preferred embodiment, as shown in FIG.  2 . The first and second rollers  03 ;  29  can also be disposed next to one another, for example in alternating fashion, in the longitudinal direction of the cylinder  01 , wherein the first rollers  03  cooperate, by the provision of a first roller support  06 , with a first deformable hollow body  04  and the second rollers  29  cooperate by the provision of a second roller support  32 , with a second deformable hollow body  33 . 
     The pivoting frame  08  described in the fourth preferred embodiment, as shown in FIG. 4, is preferably disposed so that it is stationary in relation to the cylinder  01 , and is parallel to the cylinder&#39;s rotational axis. The frame  08  and the guard  47  can be embodied so that when the guard  47  is in the closed position, there is an extremely short distance d 47 , of preferably between 20 and 25 mm, in an engagement region between the guard  47  and the cylinder  01 . When the device is disposed between two cylinders  01  that touch, for example between a plate cylinder and a rubber blanket cylinder of a printing press, the form of the frame  08  and the guard  47  can be embodied so that the device also functions simultaneously as a guard that prevents objects from being pulled in between the two rotating cylinders  01 . To this end, a maximal distance of d 12 =6 mm and/or d 47 =6 mm should be maintained in the respective outer engagement region between the cylinder  01  and the frame  08  and/or the guard  47 , for example between the free end of the leg  12  and the cylinder  01  or, when the guard  47  is open, between the free end of the guard  47  and the cylinder  01 . It is advantageous to maintain an obtuse angle toward the operational side in the above-mentioned engagement regions between the cylinder  01  and the pressing device. This can occur by correspondingly configuring the frame  08  and guard  47  or by also providing sheet metal strips, for example. 
     In a preferred embodiment of the present invention, as is also shown in FIG. 4, a stop  56  is disposed at the end of the leg  12  and is oriented toward the cylinder  01  in order to facilitate an even, guided placement of the cover  02  to be installed on the cylinder  01 . The stop  56  can be of one piece construction. Preferably, several stops  56  are provided on the frame  08 , which several stops  56  are disposed next to each other and which are spaced apart from one another in the longitudinal direction of the frame  08 . They are attached to the frame  08  by use of positive and/or frictional engagement devices, for example by the use of screws  57  at a curved lower end of the leg  12 . However, the stops  56  can also be part of the leg  12 . If the stops  56  are attached to the leg  12  by screws  57 , it is advantageous for the stops  56  to be adjustable in relation to the position of the cylinder  01 , for example by embodying bores  58  in the leg  12  and through which the screws pass as oblong holes. 
     On a side  59  of stop  56 , which side  59  is oriented toward the cylinder  01  and which cooperates with a leading end  62  of the cover, such as a printing plate  02 , the form and position of the stop  56  are embodied in such a way that a distance d 56  between the side  59  of the stop  56  and the surface of the cylinder  01  tapers in the circumference direction of the cylinder  01 . For example, the side  59  can be embodied of two pieces and so that it is angled in relation to a line  61  extending parallel to the rotation axis of the cylinder  01 , wherein the first section of the side  59  disposed in the insertion region of the leading end  62  of the printing plate  02  is inclined less sharply in relation to the cylinder  01  and the subsequent second section is inclined more sharply in relation to the cylinder  01 . The distance d 56  between the cylinder  01  and the stop  56  should, on the line  61  of the bend  61  or at least in the course of the second section of the side  59 , be less than the height d 62  of the bent leading end  62  of the printing plate  02 . 
     In accordance with the fourth exemplary embodiment of the device for pressing a cover against a cylinder, in accordance with the present invention, the installation of the cover  02  on the cylinder  01  by use of the device of the present invention takes place as follows: The cylinder  01  is initially rotated into a position in which a cylinder groove or channel opening  63  that will receive the bent leading end  62  of the cover, such as a printing plate  02 , when cylinder  01  is a forme cylinder, comes to rest approximately opposite from the stops  56 . With its bent leading end  62 , the printing plate  02  is inserted between the forme cylinder  01  and the pressing device and is positioned against the stops  56 . When the printing plate  02  is inserted or pushed further toward the stops  56 , the bent leading end  62  of the printing plate  02  is prestressed by the form of the stops  56  and automatically snaps into the cylinder channel opening  63 . After the leading end  62  of the printing plate has been clamped in the channel, the deformable hollow body  04  is acted on with pressure fluid. This opens the guard  47  in response to the movement of the strut  17  and simultaneously places several individually movable rollers  03  against the cylinder  01 . If space conditions require, after the leading end  62  of the printing plate  02  is clamped in position and before the opening of the guard  47  and the deployment of the rollers  03 , the cylinder  01  can first be repositioned, either in the production direction or in the opposite direction. The repositioning of the cylinder  01  occurs, in an advantageous fashion, so that the rollers  03  are placed against the cover, such as the printing plate  02 , either directly on, or close to the channel opening  63  in the cylinder  01 . After the rollers  03  are deployed, the cylinder  01  is rotated in the production direction until the rollers  03  again come to rest against the channel  63  and now will guide a trailing plate end into the channel opening  63 . 
     The opening and closing of the locking mechanisms for the leading end  62  of the printing plate or cover  02  and the trailing end of the plate or cover  02  in the channel opening  63  are preferably actuated automatically and are coordinated with the sequence of the above-described procedures of the plate replacement. The removal of the cover  02  from the cylinder  01  essentially occurs in a reverse sequence. 
     All of the preferred embodiments of the present invention, as set forth above, have the common feature that a single adjusting mechanism  04  or  33  is used to respectively place a number of first rollers  03  and/or a number of second rollers  29 , which are actuated simultaneously and directly, against the cylinder  01 . This is because the adjusting mechanism, in the form of a deformable hollow body  04 , cooperates with the surface  09 ;  34  of a roller support  06 ;  32 . In all of the preferred embodiments, in the deployed position A, the same force is exerted directly on all of the rollers  03 ;  29  over the length of the device. 
     While preferred embodiments of a device for pressing a cover on a cylinder in accordance with the present invention have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that a number of changes in, for example, the overall size of the cylinder, the type of rotary printing press used, 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.