Abstract:
A roller for a printing machine includes a rotatably mounted roller body which can be placed on or against at least one counter roller. The roller has at least one axis and at least one spring element which is arranged between the roller body and a machine frame. The spring element is disposed between the roller body and the part of the axis which is used to secure the roller.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is directed to a roller for a printing press. The roller includes a rotatably supported roller body.  
         BACKGROUND OF THE INVENTION  
         [0002]    A roller is known from EP 0 941 849 A1. Shaft sections of the roller described in that document project from each of the roller end faces and are rotatably seated in bearing shells. The bearing shells are connected with the press frame by spring elements, so that when the roller is placed against a counter-pressure roller, the roller body can yield radially. Because of this resilient seating of the roller, size deviations, for example as a result of increased wear, can be compensated for. It is furthermore possible to provide defined contact pressures between the roller and counter-pressure roller in a simple way because of the resilient seating.  
           [0003]    U.S. Pat. No. 4,756,249 A describes an inking roller, whose shell tube is seated, resilient in the radial direction, on its shaft.  
           [0004]    DE-PS 15 61 014 shows an inking roller whose shaft is received in a resilient bearing.  
         SUMMARY OF THE INVENTION  
         [0005]    The object of the present invention is directed to providing a roller.  
           [0006]    This object is attained in accordance with the present invention by providing the roller with a rotatably supported roller-body. The roller has at least one shaft. At least one spring element is arranged between the roller body and the frame of the printing press which supports the roller. The spring element may be in the shaft. It may have a rotationally symmetrical cross-section. Alternatively, the spring element cross-section may not be rotationally symmetrical but may instead be shaped in accordance with a predetermined directionally-dependent spring characteristic. The shaft of the roller may be at least partially in the form of a bar spring.  
           [0007]    The spring element of the roller in accordance with the present invention is arranged between the roller body of the roller and the part of the shaft used for fastening the roller. A special advantage of the present invention lies in that particularly compact structures are possible because of the arrangement of the spring element between the roller body and the shaft. It is moreover possible to retrofit rollers of existing printing presses, which are not resiliently seated, to be able in this way, to achieve the desired resilient effect without requiring extensive corrective structural measures.  
           [0008]    The structural embodiment of the shaft itself, for use in providing the arrangement of the spring element between the roller body and the shaft, can basically be arbitrary. It is thus conceivable, for example, to embody the shaft essentially in one piece, so that it extends from one roller end face to the other roller end face in the interior of the roller body. In connection with longer rollers, it is particularly advantageous if the roller body is seated on two separate shafts, each of which shafts is arranged in the area of a roller end face.  
           [0009]    The structural embodiment of the spring elements can basically be arbitrary. It is, for example, conceivable to arrange spring-seated bearing shells between the shaft and the roller body, so that the roller body can be displaced against a spring force in a radial direction in relation to the shaft. If the shaft itself is embodied as a spring element, this constitutes a particularly simple and cost-effective option for providing the structural principle of the present invention. In other words, this means that, because of its embodiment, the shaft permits an at least small elastic deformation, so that the roller body can be displaced in relation to the clamping of the shaft opposite to the required resilient restoring force required for the deformation of the shaft.  
           [0010]    In accordance with a preferred embodiment of the present invention, the shaft is configured in the manner of a bar spring element. Based on the bar shape of the shaft, it is possible to deform the shaft transversely in relation to is longitudinal axis, so that, in this way, it makes the spring effect possible.  
           [0011]    If the bar spring element, which is used as the shaft, has a rotationally symmetrical cross section, it is possible, because of this, to achieve that the spring characteristic of the bar spring element is substantially identical in all radial directions.  
           [0012]    If the bar spring element has a cross section which is not rotationally symmetrical, it becomes possible, because of an appropriate selection of the cross sections, or of a suitable arrangement of the cross section following the mounting of the shaft, to set a predetermined, and in particular a directionally dependent, spring characteristic.  
           [0013]    This is of particular advantage if the roller is intended to be simultaneously placed against several counter-pressure rollers. By an appropriate selection of the cross section of the shaft, or of its arrangement following the installation of the roller, it is possible to set different spring characteristics with respect to the various counter-pressure rollers. It then follows that if, for example, a shaft with a rectangular cross section is selected, the bar spring element has a considerably steeper characteristic spring curve, with respect to deformations in one direction, namely in a direction of the greatest width of the bar spring element, than in a direction extending perpendicularly thereto, namely in the direction along the shortest width of the bar spring element.  
           [0014]    If the cross section, or the arrangement of the cross section of the bar spring element, is suitably selected, it is possible to mount the bar spring element with a prestress which is a function of the direction. In this way, the reaction forces caused by the weight of the roller, which act with different force on the various counter-pressure rollers, are compensated. As a result, it is possible that the same reaction forces will act on all counter-pressure rollers which are placed against the roller, independently of their installed position in relation to the vertical direction. The weight of the roller no longer has a substantial effect on the contact pressure between the roller and the various counter-pressure rollers.  
           [0015]    In some applications, for example if the roller is embodied as an application roller, which is simultaneously placed against a forme cylinder and a distribution cylinder, it is necessary that the bar spring element is not substantially resiliently compressed in at least one direction.  
           [0016]    In order to be able to assure sufficient dynamic stability in all operational situations, in spite of the resilient seating of the roller body on-the shaft, in some applications it is desirable for a damping element to be arranged between the shaft and the roller body. By the use of this damping element, it is possible to damp out an excitation of the roller, in particular within the range of the roller&#39;s resonance frequencies, to such a degree that the roller body remains in a dynamically stable state at all times. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows.  
         [0018]    Shown are in:  
         [0019]    [0019]FIG. 1, a roller in accordance with the present invention and with its cross section partially represented, in  
         [0020]    [0020]FIG. 2, a schematic side view of a roller frame with five rollers, and in  
         [0021]    [0021]FIG. 3, a schematic side view of a roller frame with three rollers. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    Referring initially to FIG. 1, there may be seen, generally at  01 , a roller in accordance with the present invention. The roller  01 , which is partially represented in FIG. 1, has a rotatably seated roller body  02 , whose outer circumferential surface can be placed against a counter-pressure roller, which is not specifically represented in FIG. 1. The roller  01  is fastened on a press frame  04  of a printing press by the use of a bearing element  03 . The roller  01 , which may be, for example an application roller, can also be seated in levers for engagement and disengagement with the counter-pressure roller. In this connection, the bearing element  03  can be displaced by remote control for accomplishing a movement of the roller  01  in relation to the press frame  04 , or to change the contact pressure between the roller  01  and the counter-pressure roller which is not specifically shown.  
         [0023]    The roller body  02  is rotatably seated on shafts  07 , only one of which is shown in FIG. 1, by the use of two bearings  06 , for example two rolling bearings  06 , each of which is arranged in the area of an end face of the roller body  02 . Alternatively to the preferred embodiment represented in FIG. 1, it is, of course, also within the scope of the present invention to provide rolling bearings  06  in the bearing element  03  for the rotatable seating of the rolling body  02 , in order to permit rotatory relative movements between each shaft  07  and the associated bearing element  03 .  
         [0024]    Each shaft  07  is embodied as a spring element, for example as a bar spring. This is constructively accomplished in that the shaft  07  has a spring element  08 , for example a bar spring element  08 , which can be elastically deformed transversely to its longitudinal axis  11 . The bar spring element  08  is rigidly clamped to the bearing element  03  at a first end, and its second, opposite end is rigidly fastened on the end face of a sleeve  09 . If a force acts on the roller body  02  radially in respect to the longitudinal axis  11  of the roller  01 , the bar spring element  08  is at least slightly elastically deformed by this force, so that a spring force is created, which spring force is directed opposite to the force acting on the roller body  02 .  
         [0025]    The spring element  08  can also be embodied as a hollow spring element  08  in order to make possible the inlet and outlet of a cooling medium-conducting roller body  02 .  
         [0026]    The flexural strength of the bar spring element  08  has been selected to be such that a defined force is generated largely independently of its bending.  
         [0027]    A damping element  12  is provided in a gap between the sleeve  09  and the bar spring element  08 . This is constructively achieved in that the gap between the sleeve  09  and the bar spring element  08  is filled with a suitable oscillation-damping material.  
         [0028]    The bar spring element  08 , as depicted in FIG. 1, has a cross section in the shape of a circle so that, in the situation of the placement of the roller body  02  against two counter-pressure rollers, the same characteristic spring curve results in both placement directions. If the roller  01  is set with the correct flattening against a counter-pressure roller by the use of generally known engagement devices, this setting is also maintained with a constant force by the bar spring element  08  even under dynamic stresses. Occurring oscillations are kept below a tolerably threshold by use of the damping element  12 .  
         [0029]    [0029]FIG. 2 shows an inking unit  13  for use with a plate cylinder  14 , and including two distribution cylinders  16  and  17 , a first roller  18 , for example an inking roller  18 , and a second roller  19 , for example an application roller  19 . Starting at the distribution cylinder  17 , ink is transferred to the plate cylinder  14  via the inking roller  18 , the distribution cylinder  16  and the application roller  19 . The shaft of the inking roller  18  has a spring element  21  in the shape of a circle, for example a bar spring element  21 , so that the characteristic spring curve of the inking roller  18 , when placed against the distribution cylinders  16  and  17 , is approximately the same in both engagement directions  22  and  23 .  
         [0030]    In contrast to the shaft spring element  21  of the first, inking roller  18 , the shaft of the second, application roller  19  has a rectangular spring element  24 , for example a bar spring element  24 . Because of the rectangular cross-sectional shape of the bar spring element  24  and because of its correspondingly suitable mounting arrangement, it is achieved that, when application roller  19  is placed against the plate cylinder  14  in the engagement direction  26 , the bar spring element  24  makes possible a substantially rigid seating of the roller  19  against the cylinder  14  with a very steep characteristic spring curve. In other words, this means that the application roller  19  can only be displaced in the engagement direction  26  by correspondingly large forces. To set the flattening force of the application roller  19  against the plate cylinder  14 , it is necessary for the bearing element  03  to be embodied so as to be displaceable in the engagement direction  26 . In that case, the bar spring element  21  can again be twisted in the engagement direction  26  for fine adjustment. When the application roller  19  is placed against the distribution cylinder  16  in the engagement direction  27 , the application roller  19  is relatively easily resiliently compressed, since in this direction the bar spring element  24  has its narrowest width.  
         [0031]    In the situation of an asymmetric spring element, the spring element can be embodied to be rotatable, so that the contact pressure, viewed from the basic setting, can be increased, as well as reduced. In this case, the bearing element  03  is embodied in such a way that the spring element can be clamped.  
         [0032]    A roller combination, including a roller  28  which is placed against two rollers  29  and  31 , for example two counter-pressure rollers  29  and  31 , is represented in FIG. 3. Since the counter-pressure roller  31  is arranged below the roller  28 , a force of weight  32  caused by the weight of the roller  28  acts on the counter-pressure roller  31 . So that, as the end result following the installation of the roller  28 , the same engagement forces  33  and  34  act on the counter-pressure rollers  29  and  31 , the roller  28 , whose shaft has a spring element  36 , for example a bar spring element  36 , is mounted in such a way that the bar spring element  36  is differently pre-stressed along the engagement directions  37  and  38 . It is possible, by a suitable selection of the difference between the pre-stresses along the engagement directions  37  and  38 , to compensate for the force of the roller weight  32  acting on the counter-pressure roller  31 , so that as a result the engagement forces  33 , or  34 , agree, as desired, in their amounts. By an appropriate selection of the pre-stress, it is, of course, also possible to set a different ratio of the various forces acting between the rollers  28 ,  29 ,  31 .  
         [0033]    The shaft  07  and the roller body  02  may be connected with each other, for example, so they cannot rotate in respect to each other. In another embodiment, the roller body  02  may rotate in relation to the shaft  07 .  
         [0034]    The spring element  08  typically has a flat characteristic spring curve.  
         [0035]    The force generated by the spring element, for example an engagement force against a counter-pressure roller and/or counter-pressure cylinder, is almost independent of bending. For example, the force change is less than 50% in the area of the bending which occurs.  
         [0036]    While preferred embodiments of a roller, 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 various changes in, for example, the overall size of the roller, the specific material utilized for the roller body and for the oscillation dampening material, 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.