Abstract:
A device is used to set a contact pressure between a displaceable roller and another roller or for moving the displaceable roller with respect to the other roller. At least one actuator is subjectible to the action of a pressure medium and presses the displaceable roller toward the other roller with an adjustable force. The pressure of the pressure medium can be adjusted by a valve. A switchover device is provided for use in connecting the valve to different actuators, as desired.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This U.S. patent application is the U.S. national phase, under 35 U.S.C. 371, of PCT/DE2003/002946, filed Sep. 5, 2003; published as WO 2004/028810A1 on Apr. 8, 2004, and claiming priority to DE 102 44 046.8, filed Sep. 21, 2002, the disclosures of which are expressly incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is directed to devices and to methods for setting the contact pressure of a displaceably seated roller. The contact pressure, or a spacing distance between the displaceable roller and a second roller is variable by the use of the actuator that can be charged with a pressure medium.  
       BACKGROUND OF THE INVENTION  
       [0003]     A plurality of rollers are contained in generally conventional printing presses, such as web-fed rotary printing presses, for example. Inking rollers, in particular, are provided in such presses, which inking rollers are used for transferring ink from an ink reservoir to the plate cylinder. It is possible to meter the ink that is transferred to the plate cylinder by the inking rollers, so that the ink is being transferred as a uniform film of a defined thickness. Because of this, it is possible to compensate for interferences, such as for example, fluctuations in speed and rotary vibrations.  
         [0004]     Dampening rollers can also be provided. These dampening rollers transfer a dampening agent, for example water, to the printing group.  
         [0005]     Pairs of rollers are often formed by rollers which are in engagement with each other. At least one of the rollers in the pair has a cylinder surface made of an elastic material, so that this cylinder surface can be deformed at least slightly, depending on the contact pressure exerted on it by the roller opposite it. As a result, a contact area, which extends in a straight line between the rollers, and which is called a contact strip, appears because of the elastic deformation of the roller surface. The circumferential width of the contact strip can be varied by adjusting the contact pressure between the rollers. The width of this contact strip has a considerable effect on the print result. If, for example, the contact strip in an inking unit is too narrow, not enough ink is being transferred. In cases in which the contact strips are too wide, the elastic roller can be damaged by the kneading effect occurring because of this excessively wide contact strip.  
         [0006]     To be able to always correctly adjust the strip width, in particular as a function of the press operating conditions, for example the temperature of the printing presses or their degree of wear, it is necessary to seat one of the rollers displaceably. This displaceably seated roller can be pushed, by an actuator, with an adjustable force, in a direction toward the opposite roller. Once the correct contact pressure between the two rollers has been found, a fixation device for use in fixing the first roller in place, with respect to the second roller, is operated to maintain the contact pressure permanently.  
         [0007]     A device for setting a contact pressure between two rollers is known from DE 197 19 305 A1. By use of the seating arrangement described in that document, the displaceably seated roller is pressed against the opposite roller by a spring, which spring is supported on the frame of the printing press. Because of this spring-biased roller displacement, a defined contact pressure between the two rollers always occurs as a function of the respectively selected characteristic curve of the spring. A clamping mechanism, with a clamping lever and with a clamping plate, and useable for fixing the roller in the pressed-on place, is described, by the use of which clamping mechanism the roller shaft can be fixed in place on the frame of the printing by a frictional connection.  
         [0008]     A device for the semi-automatic adjustment of rollers is known from DE 199 19 733 A1. An adjustably seated roller is maintained in a roller holder, which, in turn, is seated in a frame holder that is fixedly arranged on the frame. In this case, the roller holder and the frame holder can be displaced, in relation to each other, and are connected with each other by a spring-elastic assembly. The spring-elastic assembly here has a defined prestress, so that the roller, which is displaceably seated on the roller holder, can be pressed against the opposite roller with a defined contact pressure. Arresting bolts are provided for use in fixing the roller holder in place on the frame holder, and by whose advancement, the roller holder can be clamped, in a frictionally connected manner, on the frame holder.  
         [0009]     DE 38 08 142 A1 describes a device for seating two cylinders. In this case, a contact pressure between two rollers, which two rollers can be placed against and away from each other, can be changed by altering the pressure of a pressure medium. A switching device is also provided, by use of which, the pressure medium can be selectively conducted to different actuators.  
         [0010]     DE-OS 16 11 303 discloses a device for bringing a printing cylinder of a rotogravure press into and out of contact. A pressure reduction valve is provided.  
         [0011]     Inking rollers are known from U.S. Pat. No. 2,774,301 and GB 1 213 935. These rollers can be brought into contact by the use of actuators which are operated by a pressure medium. Here, a valve for setting the level of the pressure and at least one shut-off valve are provided.  
       SUMMARY OF THE INVENTION  
       [0012]     The object of the present invention is directed to providing devices and methods for setting a contact pressure of an adjustably seated roller.  
         [0013]     In accordance with the present invention, this object is attained by the provision of a device for setting the contact pressure between a displaceably seated first roller and a second roller. At least one actuator, which is chargeable with a pressure medium, is utilized. Two valves can be used to form two different contact pressures. The operation of the actuator can take place in a timed manner. If the second roller has a break in its surface, the contact between the rollers takes place at a defined angular position of the second roller. The movement of the one roller takes place at a low number of roller revolutions or speed. Selectively actuatable fixation devices can be used to hold selected rollers in position.  
         [0014]     The actuator, which is useable for setting the contact pressure of the devices, is embodied in the manner of a pressure body, which pressure body can be charged with a pressure medium, such as a precompressed gas, and in particular compressed air. Valves are provided for use in adjusting the pressure of the pressure medium in order to be able to set the contact pressure. Since a multitude of adjustable rollers is provided in a typical dampening unit or inking unit, normally a number of valves corresponding to the number of actuators would be required, which larger number of valves means a large outlay in technical apparatus. This large outlay is avoided by providing a switching device, by the use of which switching device, the control valves can be selectively connected with different actuators. This means that the adjustable rollers cannot all be adjusted at the same time. Instead, only those actuators, which are connected with the control valves via the switching device, can be operated. Depending on the configuration of the inking unit or the dampening unit, a few valves are sufficient for use in adjusting the entire inking or dampening unit, by the use of which few valves, the contact pressure of the different adjustable rollers can be set.  
         [0015]     In accordance with a preferred embodiment of the present invention, only two valves are provided, by the use of which two valves the pressure exerted on two actuators, at an adjustable roller, can be set simultaneously. The process for setting the different adjustable rollers is performed in such a way that one adjustable roller is adjusted by operating the two valves and, following the adjustment of that one roller, the setting of that roller is fixed by operating a suitable fixation device. Following this fixation, the adjustment of the next adjustable roller can follow.  
         [0016]     In accordance with the method of the present invention, an angular position of the second roller, against which the first roller can be pressed with an adjustable contact pressure, is determined. By controlling this angular position of the second roller, it is possible that the pressing, or the placement of the adjustable roller is then performed only in defined positions of the second roller.  
         [0017]     This type of control of the pressure is important particularly in connection with forme cylinders on whose circumference fastening assemblies, for use in fastening the printing plates on the forme cylinder, are provided. If the adjustment or the bringing into contact of the adjustable rollers is performed at an angular position in which the adjustable roller comes to rest on the fastening device of the forme cylinder, the adjusted values are distorted because of the changed diameter of the forme cylinder in the area of the fastening device. This distortion can be avoided by controlling the angular position of the second roller.  
         [0018]     In accordance with a further preferred embodiment of the present invention, the setting of the contact pressure and/or the placement of the first roller against the second roller takes place during simultaneous rotation of both of the rollers. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows.  
         [0020]     Shown are in:  
         [0021]      FIG. 1 , a schematically represented device, in longitudinal section, and in accordance with the present invention, for setting a contact pressure between two rollers, in  
         [0022]      FIG. 2 , a schematic cross-sectional view of the device, in accordance with the schematic representation in  FIG. 1 , in a base position, in  
         [0023]      FIG. 3 , a view similar to  FIG. 2  and with the device, in accordance with the schematic representation in  FIG. 1 , in a deflected position, in  
         [0024]      FIG. 4 , the device in accordance with  FIG. 1  in a perspective front view, in  
         [0025]      FIG. 5 , a cross-sectional view of a second preferred embodiment of an actuator for a device in accordance with the present invention, in  
         [0026]      FIG. 6 , an inking unit with several adjustable rollers adapted for placement against a forme cylinder, and in  
         [0027]      FIG. 7 , a switching device for the selective switching of two valves between different actuators. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]     Referring initially primarily to  FIG. 1 , there may be seen a device generally at  20 , for setting the contact pressure between a first roller  21  and a second roller  22  in accordance with the present invention. The first roller  21  can be releasably fastened, by the end of its shaft  23 , or its journal, at a quick-release locking device  24  provided on the device  20 . Such quick-release locking devices are generally known from the prior art and typically have a semi-circular bearing shell, into which semi-circular shell the ends of the shaft  23  can be placed. By fastening an upper bearing shell, which is not specifically represented in  FIG. 1 , the shaft  23  can be fixed in place in the quick-release locking device  24 .  
         [0029]     The contact pressure setting device  20  is substantially put together from a frame holder  26  and a roller holder  27 , which frame and roller holders  26  and  27 , respectively can be displaced, in relation to each other, in an actuating plane that is extending perpendicularly, with respect to the drawing plane. The frame holder  26  is comprised of a base plate  28 , which can be pivotably fastened, for example by the use of a pivot arm, on the frame of a printing press, and a sleeve body  29 . On its side facing the roller  21 , the sleeve body  29  has a recess  31 , which is sized to be engaged by a cylinder-shaped section  32  of the roller holder  27 . The interior diameter of the sleeve body recess  31 , or the exterior diameter of the cylinder-shaped section  32  have been selected such that, in the base position depicted in  FIG. 1 , a circular-cylindrical, annular gap  33  of a gap width of from approximately 1 mm to 10 mm, and in particular a gap width of approximately 2 mm, results. The maximum actuation range, for displacing the roller holder  27  relative to the frame holder  26 , is defined by the size of the gap  33 .  
         [0030]     In order to be able to accomplish the actuation movement which is required for adjusting the first roller  21 , or in order to obtain the desired contact pressure between the first roller  21  and the second roller  22 , a total of four actuators  34 , of which only two are shown in section in  FIG. 1 , and which are embodied in the form of pressure hoses  34 , are arranged in the gap  33 . These four actuators  34  are evenly distributed over the circumference of the annular gap  33 . By the use of feed lines  48  which are not represented in  FIG. 1 , but which are shown in  FIG. 4 , pressure chambers  36 , which are constituted by the walls of the actuators  34 , can be charged with a fluid medium under pressure. Depending on the respective relative pressure conditions in the four pressure chambers  36  of the four actuators  34 , a resulting force acts on the roller holder  27 . The roller  21  can thus be pressed, with the desired contact pressure, against the roller  22  by an appropriate control of the pressure in the actuators  34 . Since the air cushion, which is under pressure in the pressure chambers  36  of the four actuators  34 , is compressible, it is possible, by use of the resulting spring effect, to intercept mechanical interferences.  
         [0031]     To fix the roller holder  27  in place, relative to the frame holder  26 , plate elements  37  are fastened on the roller holder  27 . These roller holder plate elements  37  are arranged to mesh with cooperating plate elements  38  fastened on the sleeve body  29 , thus forming a multi-disk packet. For clamping the multi-disk packet formed from the plate elements  37  and  28  in a frictionally connected manner, a T-shaped plunger  39  is provided. Plunger  39  includes a circular plunger head  40  which is provided with a plunger head circular flange  41  that is engageable against an outermost plate element  37  or  38  of the multi-disk packet. A pressure plate  42  is fastened on the end of the plunger  39  opposite the circular flange  41 , and on which pressure plate  42  the spring force of a spring element  43 , which is embodied in the manner of a plate spring package  43 , acts. The spring element  43  is mounted, prestressed, between the pressure plate  42  and the sleeve body  29 . The multi-disk packet constituted by the plate elements  37  and  38  is thereby clamped, by the spring force, which is transmitted from the plunger  39  to the plate elements  37  and  38 .  
         [0032]     To displace the roller holder  27  relative to the frame holder  26 , in particular when adjusting the contact pressure between the rollers  21  and  22 , the fixation device, which is constituted by the plate elements  37  and  38 , or by the plunger  39  and the pressure plate  42 , must be released. For this purpose, a pressure connector  44  is provided in the base plate  28 . A pressure chamber  46 , formed between the pressure plate  42  and the base plate  28 , can be charged with a pressure medium, such as, for example, compressed air which is introduced into the pressure chamber  46  through the pressure connector  44 . As soon as the air pressure in the pressure chamber  46 , and acting on the pressure plate  42 , exceeds the spring force of the spring element  43 , the plunger head circular flange  41  of the plunger  39  is lifted off the outermost plate element  37  or  38 . These plate elements  37  and  38  are no longer clamped in a frictionally connected manner and can be displaced in relation to each other.  
         [0033]     Adjustment of the contact pressure between the rollers  21  and  22  takes place, for example, in the following manner. First, the pressure chamber  46  is charged with sufficient pressure, through the pressure connector, so that the plate elements  37  and  38  are no longer clamped in a frictionally connected manner. Subsequently, the actuators  34  are each charged with just enough pressure that the desired contact pressure between the rollers  21  and  22 , or between the roller  21  and further rollers, which are not specifically represented in  FIG. 1 , is formed. This results in a contact strip of the desired width being formed between the cooperating rollers. As soon as the desired setting, with the desired contact pressure between the rollers  21  and  22  has been found, the pressure in the pressure chamber  46  is released. The plunger  39  then clamps the plate elements  37  and  38  together as soon as the roller holder  27  has been fixed in the desired position relative to the frame holder  28 . Lastly, the pressure in the actuators  34  is released.  
         [0034]     The operative principle of the device  20  during the required actuating movement is represented, in a schematic manner, in  FIGS. 2 and 3 .  FIG. 2  shows the frame holder  26  with the recess  31  and the section  32  of the roller holder  27  engaging it. By the selection of the appropriate dimensions, a gap  33  is formed between the frame holder  26  and the section  32  of the roller holder  27 , in which gap  33  the actuators  34 , only represented by force arrows in  FIGS. 2 and 3 , are arranged. The possible actuating movements between the frame holder  26  and the roller holder  27  are defined by an actuating plane which, in the representation shown in  FIGS. 2 and 3 , extends in the drawing plane. The actuating range of the actuating movements is limited by the width of the gap  33 .  
         [0035]     As represented, by way of example in  FIG. 3 , the roller holder  27 , and therefore, as a consequence, the roller  21  fastened to it, can be laterally displaced in relation to the frame holder  26 , which lateral displacement is accomplished by an appropriate triggering of the actuators and the resultant force effect on the roller holder section  32 . As soon as the desired position of the roller holder  27 , in relation to the frame holder  26 , has been found, the fixation device constituted by the plate elements  37  and  38 , or by the plunger  39  and the pressure plate  42 , can be actuated, so that the position is permanently fixed and the actuators  34  need no longer be driven.  
         [0036]     In  FIG. 4 , the contact pressure setting device  20 , with the base plate  28 , is represented in a perspective front view. The sleeve body  29  is fastened by the use of four fastening screws  47  on the base plate  28 , schematically represented in  FIG. 1 . Four actuators  34 , which can be charged with compressed air via feed lines  48  and which are all embodied in the form of pressure hoses  34 , are arranged between the sleeve body  29  of the frame holder  26  and the roller holder  27 , on whose forward oriented side, the half-shell-shaped quick-release locking device  24  can be partially seen, as shown in  FIG. 1 . The recognizable plate elements  37  and  38  can be relaxed by operation of the pressure plate  42 .  
         [0037]     The extraordinarily compact construction of the device  20  can be appreciated which device  20 , because of its entirely rotationally symmetrical design, except for the base plate  28 , has a smaller diameter than the roller  21  itself, as may be seen in  FIG. 1 .  
         [0038]      FIG. 5  shows, in cross-section, a second preferred embodiment of an actuator  50  for a device  20  in accordance with the present invention. The basic structure of the device  20 , with a frame holder  26 , a roller holder  27  and a fixation device for fixing the roller holder  27  in place relative to the roller holder  26  corresponds to the construction described in  FIG. 1  and therefore need not be further explained in connection with this second preferred embodiment. A cylinder-shaped diaphragm  51 , whose proximal and distal edges are connected with the interior diameter of the sleeve body  29 , which is not specifically represented in  FIG. 5 , is arranged in the gap  33  to constitute the actuator  50 . Moreover, the diaphragm  51  is connected, in four axially extending strip-shaped areas  52 , with the interior diameter of the sleeve body  29 , such as, for example by being glued in, so that, as a result, four pressure chambers  53  are formed by the sleeve body  29  and the diaphragm  51 , which four pressure chambers  53  are evenly distributed over the circumference of the gap  33 . The pressure chambers  53  can each be charged with compressed air via pressure inlet openings  54  so that, as a function of the respective pressure in the four pressure chamber  53 , a resultant force acts on the section  32  of the roller holder  27 .  
         [0039]     An inking unit  56  is represented in  FIG. 6 , by the use of which, printing ink can be transferred from a roller  57  to a roller  22   a  embodied in the manner of a forme cylinder  22   a . Five adjustable rollers  21   a ,  21   b ,  21   c ,  21   d ,  21   e  are provided in the inking unit  58  for transferring the printing ink from roller  57  to forme cylinder  22   a . The ends of the adjustable rollers  21   a  to  21   e  are each seated in contact pressure setting devices  20 , which is indicated in  FIG. 6  by the corresponding actuators  34 .  
         [0040]     Also, four or five rollers  21   a ,  21   b ,  21   c ,  21   d ,  21   e , for example a dampening application roller and three or four ink application rollers, can be placed against the forme cylinder  22   a.    
         [0041]     The rollers  21   a ,  21   c ,  21   e  can be placed against the roller  22   a  by the corresponding actuators  34  being charged with pressure. After bringing the rollers  21   a ,  21   c ,  21   e  into contact, the contact pressure between the various rollers  57 ,  21   a  to  21   e ,  22   a  can be adjusted by charging the various actuators  34  at the rollers  21   a  to  21   e  with pressure.  
         [0042]     One or several plate end fastening devices  58  or axially extending cylinder channels or breaks  58  are provided on the roller  22   a , which fastening devices or breaks  58  are, in particular, structured in the form of a gap  58 . The front or the rear edges of a printing plate can be fixed in place in the fastening device  58 , which is thus used for fastening the printing plate on the roller  22   a . The angle of rotation of the roller  22   a  is detected by a sensor, which is not represented, and this position is passed on to a control device. When placing the rollers  21   a ,  21   c ,  21   e  against roller  22   a , or when setting the contact pressure of these rollers  21   a ,  21   c ,  21   e  against roller  22   a , the respective angle of rotation of the roller  22   a  is taken into consideration in order to prevent, in this way, the rollers  21   a ,  21   c ,  21   e  resting against, or contracting the break  58  when being brought into contact, or when adjusting the contact pressure. The adjustment of the rollers  21   a  to  21   e , or their being placed against the roller  22   a , can also take place with the printing group rotating and with the roller  22   a  rotating. The adjustment of the contact pressure and/or the placement of the first rollers  21   a  to  21   e  against the second roller  22   a , takes place at low numbers of rotation, in particular at speeds of from 3,000 to 5,000 revolutions/h.  
         [0043]     A switching device  59 , as represented in  FIG. 7 , is suitable for controlling the totality of  20  actuators at the adjustable roller  21   a  to  21   e  on one side. The switching device  59  is shown schematically in  FIG. 7 , and will be briefly explained in what follows.  
         [0044]     A pressure medium, such as, for example, compressed air, can be taken, at a sufficiently high pressure level, from a pressure reservoir  61 . The pressure medium flows via two valves  62 ,  63 , in particular two pressure control valves  62 ,  63 , into two separate pressure chambers  64 ,  66 . A specific pressure level prevails in each of the separate pressure chamber  64 ,  66  as a function of the respective position of the pressure control valves  62  and  63 . The pressure set in each of the two separate pressure chambers  64  or  66  can be transmitted to the actuators  34  associated with each such pressure chamber  64 ,  66  via pressure lines  67  assigned to each actuator  34 .  
         [0045]     Switching of the switching device  59  takes place in a clocked or timed manner. The length of a time pulse, for adjusting an adjustable roller  21   a  to  21   e  of the inking unit  56  or the dampening unit, is from 0.1 to 2 seconds, and, in particular, is 0.5 seconds.  
         [0046]     Blocking arrangements, which are not specifically represented in  FIG. 7 , and which may be, for example, check valves, are provided in the switching device  59 , so that it is selectively possible to block various ones of the pressure lines  67  connected to the pressure chambers  64  and  66 . If the contact pressure is now to be set at an adjustable roller  21 , all of the pressure lines  67  leading to the actuators  34  for other roller  21 , and not required for the adjustment of the selected roller  21 , are blocked. The result of this is that the air pressure set by means of the pressure control valves  62 ,  63  is only transmitted to those actuators  34  which are involved in the adjustment of the respectively desired roller  21 . Following the adjustment of this roller  21 , the resultant contact pressure is set or held by operating the associated fixation device. The next adjustable roller  21  can be then adjusted by switching the switching device  59  to open the valves associated with that roller  21 .  
         [0047]     The following alternative is possible in place of the switching device  59  with its blocking arrangement.  
         [0048]     The air pressures set by the two pressure control valves  62 ,  63  are simultaneously present at the actuators  34 ,  50  of several adjusting devices. An adjustment of the contact pressure takes place only at adjustment devices whose fixation device is opened.  
         [0049]     The placement of the roller  21 ,  21   a ,  21   b ,  21   c ,  21   d ,  21   e , to be put into contact with the surface area of the second roller  22 ,  22   a  takes place, in relation to the circumferential direction, at a distance of less than 20 mm from the leading end of the break  58 .  
         [0050]     Setting the contact pressure means that the contact pressure, in the state where the roller is placed against, or in contact with, another roller, can be changed prior to it being brought into such contact. In the contacted state, the surface pressure of the roller can be changed, in addition to the roller being moved to the disengaged state.  
         [0051]     While preferred embodiments of devices and methods for setting the contact pressure of a displaceably mounted roller, in accordance with the present invention, have been set for fully and completely hereinabove, it will be apparent to one of skill in the art that various changes in, for example the overall sizes of the rollers, the source of the pressure medium, and the like can 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.