Abstract:
A printing unit is comprised of at least two side frame parts whose distance, relative to each other, can be modified in a horizontal direction. Each printing unit receives at least one printing group or parts of a printing group. At least one of the side frame parts can be moved between a closed functional position, in which the side frames are moved together and are fixed relative to one another, and an open position, in which they are spaced from each other. In order to fix or to secure the side frame parts relative to one another, at lease one closure device is provided. The at least one closure device is comprised of a cylinder that can be used to pretension the side frame parts into the closed functional position. The cylinder carries a piston rod that is adapted to carry out a stroke movement. The closure device is configured as a swivel tensioning element. The piston rod is arranged such that it carries out a pivoting movement about a longitudinal axis of the piston rod, in addition to the stroke movement. The piston rod may also be pivoted about a longitudinal arm of the piston rod, in addition to the stroke movement.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national phase, under 35 U.S.C. 371, of PCT/EP 2008/059061, filed Jul. 11, 2008, published as WO 2009/049935 A1 on Apr. 23, 2009, and claiming priority to DE 10 2007 000 860.2, filed Oct. 12, 2007, the disclosures of which are expressly incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention is directed to a printing unit comprising at least two side frame parts whose distance relative to one another can be modified in a horizontal direction. Each of the side frame parts accommodates at least one printing couple or parts of a printing couple. At least one of the side frame parts can be moved between a closed functional position and the open position. At least one closure device is provided and pretension the side frame parts in the closed functional position. 
     BACKGROUND OF THE INVENTION 
     A printing unit, which is embodied as a printing tower with four blanket-to-blanket printing units or arch-type printing units arranged one above the other, is known from WO 2005/037553 A1. This printing unit comprises two frame parts that are movable relative to one another, each with two side frame plates arranged opposite one another. Three centering or locking devices, which may be embodied as hooks, are assigned to each side frame plate 
     further printing unit, which is embodied as a printing tower with four blanket-to-blanket printing units or arch-type printing units arranged one above the other, is known from WO 2005/037552 A1. A frame part that is movable relative to a stationary frame part is mounted on rollers. The rollers can be moved into a retracted position. This will allow the weight of the movable frame part to be supported against a stationary base. 
     A further printing unit, which is also embodied as a printing tower with four blanket-to-blanket printing units or with four arch-type printing units arranged one above the other, is known from EP 07 49 369 B1. This printing unit is provided with a stationary frame part and with a movable frame part, which is mounted on rollers. Two frame parts can be locked in the operating position. 
     A further printing unit, that may also be embodied as a printing tower, with four blanket-to-blanket printing units arranged one above the other, is known from EP 17 67 359 A2. The frame parts, that are movable relative to one another, are provided. The printing couple cylinders of the blanket-to-blanket printing units are mounted in hydraulically actuable linear bearings so as to be displaceable radially. 
     DE 601 18 828 T2 discloses a printing unit which is comprised of at least two side frame parts, whose distance relative to one another can be modified in a horizontal direction. Each side frame part accommodates a printing couple or parts of a printing couple. At least one of the side frames is movable between a closed functional position, in which the side frame parts are moved together and fixed relative to one another, and an open position, in which they are spaced from one another. At least one closure device is provided, which closure device comprises a cylinder for pretensioning the side frame parts in the closed, functional position. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a printing unit comprising at least two side frame parts whose distance relative to one another can be modified in a horizontal direction. 
     The object is attained in accordance with the present invention by the provision of at least two frame parts whose distance relative to each other can be modified in a horizontal direction. At least one of these side frame parts can be moved, with respect to the other side frame part, between a closed, functional position and the open position. A closure device is used to fix the side parts to each other in the closed, functional position. The closure device includes a cylinder and piston, with an associated piston rod. The piston rod is positioned to be able to execute a pivoting movement around a longitudinal axis of the piston rod in addition to its stroke movement. 
     The one cylinder for use in pretensioning the side frame parts in the closed, functional position, in particular, is a closure device comprising a tension cylinder, which can be embodied, in particular, as a hydraulic swivel tensioning element. Multiple closure devices are preferably provided, thereby ensuring proper positioning of the stops of the side frame parts and a uniform fixing of the side frame parts. In this manner, the complicated adjustments, which were previously required to stress all the hooks uniformly, can be dispensed with. 
     The cylinder/piston assembly, which is provided in accordance with the preferred embodiment of the present invention and which, in particular, is centered or, for example, is positioned at the load center or near the load center, and in the underframe of the printing unit. This assembly thereby supports a precise positioning of the movable side frame part during operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention are shown in the set of drawings and will be specified in greater detail in what follows. 
       In the drawings: 
         FIG. 1  is a schematic side elevation view of a printing unit with one stationary side frame part and one moveable side frame part whose spacing from the stationary side frame part is variable; 
         FIG. 2  is a perspective view of the frame of the printing unit of  FIG. 1 , wherein the side frame that faces the viewer is not shown; 
         FIG. 3  is a side view of the frame of  FIG. 2 , and which also shows the horizontal separation of the frame; 
         FIG. 4  is a perspective representation of a closure device for locking the side frame parts of the printing unit of  FIG. 1  to  FIG. 3 , and a stop for securing the side frame parts in their functional position in accordance with the present invention; 
         FIG. 5  is a further perspective representation of the closure device of  FIG. 4 , and a device for centering the two side frame parts in the functional position; 
         FIG. 6  is a side elevation view of the closure device of  FIG. 4  or  FIG. 5  with side frame parts in the functional position; 
         FIG. 7  is a perspective view of the base of the frame of the printing unit of  FIG. 1  through  FIG. 3 , along with various components printing unit arranged on the base; 
         FIG. 8  is an enlarged representation according to  FIG. 7 , which, in particular, also shows the cylinder/piston assembly for moving the displaceable side frame part; 
         FIG. 9  is a detailed view of the base of  FIG. 7  taken from a different direction and showing, in particular, a partial view of the guidance track of the movable side frame part by the use of running blocks; 
         FIG. 10  is a side elevation view of the configuration of  FIG. 9   
         FIG. 11  is a perspective view of a running block from the bottom, with a guidance track according to  FIG. 9  or  FIG. 10 ; 
         FIG. 12  is a perspective view of a running block support with a guidance track according to  FIG. 9  or  FIG. 10 ; 
         FIG. 13  is a cross-sectional view of the running block support of  FIG. 12 ; 
         FIG. 14  is an additional view of the running block support of  FIG. 13 ; 
         FIG. 15  is a perspective partial view of an alternative embodiment of a guidance track for the movable side frame part by the use of sliding block assemblies; 
         FIG. 16  is a side view of the representation of  FIG. 15 ; 
         FIG. 17  is a plan view of the representation similar to  FIG. 15 , but without sliding block supports; 
         FIG. 18  is a perspective view of a sliding block of a sliding block assembly of  FIG. 15 ; 
         FIG. 19  is a top plan view of the sliding block of  FIG. 18 ; 
         FIG. 20  is a cross-sectional view of the sliding block of  FIG. 19 ; 
         FIG. 21  is an additional side view of the sliding block of  FIG. 19 ; and 
         FIG. 22  is a perspective view of the sliding block of  FIG. 19 , as viewed from the bottom. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a highly simplified, schematic side elevation view of a printing unit  01  or printing press  01 , and in particular, depicts a web-fed rotary printing press  01  in the form of a printing tower  01 , which preferably is a printing press  01  that prints in multiple different colors. Printing unit  01  is comprised, for example, of four printing couples  04 , namely blanket-to-blanket printing units  03 , which are arranged vertically, one above the other, in a frame  02 . A print substrate  05 , such as, for example, a web of material  05 , and especially a paper web  05 , passes through the blanket-to-blanket printing units  03  in succession in a vertical direction. Each of these blanket-to-blanket printing units  03  is comprised of two printing couples  04 . 
     In the printing unit  01  shown in  FIG. 1 , in each blanket-to-blanket printing unit  03 , one printing couple  04  and comprising a first cylinder  06  or printing couple cylinder  06 , and in particular, a transfer cylinder  06  or a blanket cylinder  06 , which transfers printing ink and is which loaded with at least one blanket, and a second cylinder  07  or printing couple cylinder  07 , and in particular, a forme cylinder  07  or a plate cylinder  07 , which rolls against the blanket cylinder  06  and which holds one or more printing plates, are positioned on each of the two sides of the paper web  05  for accomplishing straight and verso printing. The two blanket cylinders  06  and the two plate cylinders  07  of two opposite printing couples  04  of a blanket-to-blanket printing unit  03  are arranged such that their rotational axes lie within a plane which is inclined by preferably 75° to 88° in relation to the paper web  05 . 
     An inking unit  08 , such as, for example, a roller inking unit  08  or an anilox inking unit  08 , is assigned to each printing couple  04  which is comprised of at least a blanket cylinder  06  and a plate cylinder  07 . Also assigned to each printing couple  04  is a dampening unit  09 , such as, for example, a spray dampening unit  09 . If printing will be performed in “dry offset” or “waterless offset printing,” in a manner which is not specified in greater detail, no dampening agent, and thus no dampening unit  09 , is provided. In this situation, the inking unit  08  can be embodied, for example, as an ink pump unit  08 . 
     Each printing couple  04  of the printing press  01  has at least one preferably position-controlled drive motor, which will not be specified in greater detail here. The plate cylinder  07  and the blanket cylinder  06  can be connected to one another, particularly in terms of their drive mechanism, by the use of toothed gears. Alternatively, each blanket cylinder  06  and each plate cylinder  07  can be equipped with its own drive motor, which is not specified in greater detail here. With a drive mechanism of this type, a plate change can be performed on one plate cylinder  07  independently of the performance of a plate change on another plate cylinder  07 . 
     The printing couples  04 , or their plate cylinders  07 , can be configured to accommodate multiple printing plates in an axial direction. In particular, 2, 3, 4, 5, 6, 7, or 8 printing plates can be accommodated in the axial direction. The plate cylinders  07  can be configured to accommodate one or, if applicable, to accommodate multiple printing plates in the circumferential direction, and in particular, to accommodate two printing plates in the circumferential direction. 
     In the representation of  FIG. 1 , the blanket cylinders  06  which are positioned on both sides of the paper web  05 , and each in a respective blanket-to-blanket printing unit  03 , are engaged against one another in a so-called blanket-to-blanket configuration. The blanket cylinders  06  which are engaged against one another, function alternatively as impression cylinders. Alternatively, printing couples  04  can be combined in a manner which is not specified in greater detail, to form a satellite printing unit. In each such satellite printing unit, four printing couples  04  are arranged around a shared impression cylinder which is separate from the other cylinders  06 ;  07 . The paper web  05  in each case is guided between at least one transfer cylinder  06 , that is engaged against the impression cylinder and the impression cylinder. 
     As is depicted in  FIG. 1 , the printing tower  01  comprises multiple, and in particular, comprises two separable side frame modules  11 ;  12  or side frame parts  11 ;  12  whose distance in relation to one another can be modified in the horizontal direction. In particular, the printing tower  01  utilizes one side frame part  11  which is stationary in the press or in its location, and one side frame part  12  which is displaceable in relation to the first. The displaceable side frame part  12  is displaceable along a stationary base  13  beneath it. Alternatively, both side frame parts  11 ;  12  can also be displaceably arranged. A printing couple  04  of a blanket-to-blanket printing unit  03 , including the associated components, such as inking unit  08  and, if applicable, dampening unit  09 , and optionally also including automatic or semiautomatic plate changing devices or plate magazines, which are not specifically shown here, are arranged in each side frame part  11 ;  12 . The separability of the frame  02  allows the frame  02  to be opened, which frame opening allows optimum access to corresponding printing couple components for set-up, maintenance and, if necessary, also for repairs. 
     The printing couple cylinders  06 ;  07 , such as, for example, the transfer cylinder  06  or the blanket cylinder  06  and the forme cylinder  07  or the plate cylinder  07 , are each mounted in a bearing unit  14  or in a linear bearing  14 . Preferably, both ends of each printing couple cylinder  06 ;  07  are mounted in a linear bearing  14 . A linear bearing  14  of this type supports a printing couple cylinder  06 ;  07  to allow rotation, while at the same time permitting translational movement. In other words, the linear bearing  14  provides a linear adjustment path for the printing couple cylinder  06 ;  07 , for example, for disengaging the plate cylinder  07  from the blanket cylinder  06  for the purpose of a plate change, for example. The linear bearings  14  are movable by the operation of actuators  16 , typically in the form of hydraulic pistons  16 , which have a shared hydraulic fluid supply that is not illustrated in greater detail here. For a description of the structure and the functioning of the known linear bearings  14 , refer, for example, to the previously cited EP 17 67 359 A2. 
     As is especially apparent in  FIG. 2 , in which depiction, for purposes of clarity, the side frames that face the viewer are not shown, the frame  02  comprises the stationary side frame part  11 , whose side frames that are opposite one another are fixed to the base  13 , and the displaceably mounted side frame part  12 , whose side frames that are opposite one another are displaceably mounted on the base  13 . The two side frames of the displaceable side frame part  12  are rigidly connected to one another via a lower cross rail  19  which is arranged near the base  13  so as to enable shared movement of the two side frames of the displaceable side frame part or module  12 . 
     As is shown in  FIG. 3 , at least one of the side frame parts or modules  11 ;  12 , and preferably all or both such side frame parts or modules  11 ;  12 , are each configured as being separable vertically, specifically, and especially along an essentially horizontal plane. In principle, and in particular, based upon the overall height of the respective printing tower, separation of each side frame into multiple parts is possible. In the case of the present configuration, a separation of each side frame into two pieces  11   a ;  11   b  and  12   a ;  12   b , respectively, or into two side frame halves  11   a ;  11   b  and  12   a ;  12   b , respectively, is provided. Such a separability would ordinarily be sufficient to ensure the intended problem-free, simple, and cost-saving transportability of the side frame halves  11   a ;  11   b ;  12   a ;  12   b . Especially after accomplishment of their transport, the side frame halves  11   a ;  11   b  and  12   a ;  12   b , respectively, can be securely fastened to one another, such as, for example, by being screwed to one another using threaded bolts, thereby forming the side frame parts or modules  11  and  12 , respectively. 
     As is shown in  FIG. 3 , the side frame parts or modules  11 ;  12  are separated at least essentially at the center, thus resulting in at least essentially equal side frame halves  11   a ;  11   b ;  12   a ;  12   b  of at least essentially equal dimensions. This separation and sizing is advantageous, particularly in terms of structure and handling. 
     The individual side frame halves or pieces  11   a ;  11   b ;  12   a ;  12   b  are each configured at least essentially as box-shaped, each with its open side pointing toward the outside of the printing press  01 , for example. The side frame halves  11   a ;  11   b ;  12   a ;  12   b  further have various openings  21  for use in accommodating bearing devices for the printing couple cylinders  06 ;  07  and also for accommodating peripheral apparatus of the individual printing couples  04 , such as, for example, inking unit  08  and/or inking unit rollers, dampening unit  09  and/or dampening unit rollers and the like. They are configured such that, based upon the needs of the customer, they can be used for different formats, such as, for example, using forme cylinder  07  and transfer cylinder  06  of different diameters. 
     To accomplish the horizontal movement or displacement of the side frame part or module  12 , for facilitating its variable spacing, a preferably hydraulic cylinder/piston assembly  22  is provided. Assembly  22  including a cylinder  23 , one end of which is attached to the base  13 , and a piston rod  24 , one end of which is attached to the movable side frame part  12 . This hydraulic cylinder/piston assembly  22  is also depicted in  FIG. 2 ,  FIG. 3 ,  FIG. 7 ,  FIG. 8  and  FIG. 15  through  FIG. 17 . The cylinder/piston assembly  22 , as shown most clearly in  FIG. 2 , is preferably positioned on the bottom side of the movable side frame part  12 . Specifically, the cylinder/piston assembly  22  is positioned so as to be at least essentially, and preferably precisely, centered with respect to, or, for example, at the center of the load which is supported between the oppositely arranged side frame parts  11 ;  12 . The piston rod  24  is connected to a vertically extending bolt  26 , as may be seen in  FIG. 7 , which vertically extending bolt  26  is, in turn, connected to the cross rail  19  of the side frame part  12 , which cross rail  19  is not shown in  FIG. 7 . 
     The cylinder  23  of the cylinder/piston assembly  22  is mounted at a first end, which is opposite to the end of the piston rod that is connected to the bolt  26 , and namely at its right end in the illustration of  FIG. 8 , for example, on the base  13  by the utilization of a bearing device  27 , and specifically by the utilization of a swivel bearing  27  with a vertically oriented swivel axis. The piston rod  24  is mounted at a second end, namely at the left end in the illustration of  FIG. 8 , on the movable side frame part  12  by the use of another bearing device  28 , namely a swivel bearing  28 , which is also configured with a vertically oriented swiveling axis. In the embodiment under discussion here, the piston rod  24  is connected, on its end remote from the cylinder  23 , on the cross rail  19 , and in particular, is connected on the bolt  26  which is fastened to the cross rail  19  of the moveable frame part or module  12 . 
     As is depicted schematically in  FIG. 2 , for the operation of the cylinder/piston assembly  22 , and for the operation of at least one additional hydraulic element, and in particular, a hydraulic unit of the printing unit  01 , a shared hydraulic fluid supply  29  is provided. This shared hydraulic fluid supply  29  can also supply fluid to the actuators  16  or to the hydraulic pistons  16  of the bearing units  14  or to linear bearings  14 . As depicted in  FIG. 1 , and/or the hydraulically actuable closure devices  31  and/or swivel tensioning elements  31 , which are depicted in  FIG. 2 , and which will be described in what follows. Such closure devices  31  are usable for securing the side frame parts or modules  11 ;  12  in the closed, functional position. Finally, the shared hydraulic fluid supply  29  can also supply fluid to at least one additional pressure generating device of the printing unit  01 , which is not specified in greater detail. 
     To fix the side frame parts or modules  11 ;  12  in their respective functional positions, such as, for example, in the position in which the printing unit  01  is in its production function, at least one such closure device  31  is provided. Preferably, at least one such closure device  31  is provided for each side of the frame  02 , and specifically for each side frame part or module  11 ,  12 . It is particularly preferable for at least two such closure devices  31  to be provided on each side, and especially for three such closure devices  31  to be provided on each side of each side frame part or module, as shown in  FIG. 2 . In a different printing format, it may be desirable to provide four such closure devices  31  per side. In this case, at least one closure device  31  is assigned to each side frame half  11   a ;  11   b ;  12   a ;  12   b . In the illustrated preferred embodiment, which is shown in  FIG. 2 , the configuration is such that two closure devices  31  are assigned to each of the lower side frame halves  11   b ;  12   b  on either side of the printing unit  01 , and one closure device  31  is assigned to each of the upper side frame halves  11   a ;  12   a . In the case of multiple closure devices  31 , these are preferably arranged vertically, one above the other. 
     The structure of a preferred embodiment of a closure device  31 , in accordance with the present invention, is illustrated, in particular, in  FIG. 4  through  FIG. 6 . The closure device  31  preferably comprises a hydraulically actuable cylinder  32  which pretensions the assigned side frame parts or modules  11 ;  12  in the closed functional position, any in particular, comprises a tension cylinder  32  which pulls the side frame parts or modules  11 ;  12  into their functional position. Preferably, the closure device  31  comprises at least one swivelable chucking arm  33 , which is capable of swiveling from a closed position to a released position, and which can be positioned at the unattached or free end of the piston rod  34  which slides into and out of the cylinder  32  of the closure device  31 . 
     In particular, the swivelable chucking arm  33  can be rigidly connected to the free end of the piston rod  34  of the tension cylinder  32 . The piston of the tension cylinder  32 , and its piston, can be embodied as being rotatable about its longitudinal axis. The tension cylinder  32  is then expediently constructed in a known manner such that a part of the stroke of the piston in the tension cylinder  32  is used as a rotation stroke for rotating the piston and thus for swiveling the chucking arm  33 . The closure device  31  is thus preferably embodied as a swivel tensioning element  31 . 
     The closure device  31  further comprises a mounting flange  36 , which is equipped with through holes or bores  37  with which the closure device  31  can be fastened to a side frame part or module  11 ;  12  or to a side frame half  11   a ;  11   b ;  12   a ;  12   b  by the use of suitable fasteners, such as screws  38 . Preferably, the closure devices  31  or swivel tensioning elements  31  are mounted on the stationary side frame part  11 , i.e., on the assigned side frame halves  11   a ;  11   b , as seen, for example, in  FIG. 6 . On the side frame parts  12  that are opposite in the functional position, i.e., on the assigned side frame halves  12   a ;  12   b , suitable openings  35  or holes  35  can then be formed. The swivel tensioning element  31  with its piston rod  34 , also especially along with its chucking arm  33 , can extend through an associated opening  35  in the as yet unfixed functional position. When the tension cylinder  32  is actuated, the chucking arm  33  is first swiveled until it engages behind the corresponding side frame part  11  or  12  or the corresponding side frame half  11   a ;  11   b ;  12   a ;  12   b . As piston movement continues, the chucking arm  33 , which has been swiveled into its tightened position, is increasingly pulled toward the cylinder  32 , thereby pulling the movable side frame half  12   a ;  12   b  increasingly toward the stationary side frame half  11   a ;  11   b  and into its closed position or its functional position. Additionally, the large cylinder/piston assembly  22 , which is located in the underframe, supports the precise positioning of the movable side frame part  12  during operation. 
     The openings  35  preferably each have a continuous, preferably endless, boundary. The openings  35  are preferably located in a wall that extends parallel to the rotational axes of the printing couple cylinders  06 ;  07 . In particular, these openings  35  are located in the edge of the box-shaped side frame parts  11 ;  12  or side frame halves  11   a ;  11   b ;  12   a ;  12   b ), and preferably are located in the wall that faces the opposite side frame. 
     Ports  39 ;  41  for the supply and the removal of working medium, in particular, the hydraulic oil, which is supplied and removed to the hydraulic cylinder  32  via lines  42 ;  43 , are also provided on the mounting flange  36  of the swivel tensioning element  31 . The working fluid supply and discharge lines  42 ;  43 , as described above, are connected to a shared hydraulic fluid supply  29 , which also supplies fluid to the cylinder/piston assembly  22 . All of the closure devices  31  can preferably be actuated together. 
     For use in laterally guiding and/or centering the side frame parts  11 ;  12  into their functional position, at least one centering device  44  is provided. This centering device  44 , which is shown in  FIG. 5 , aligns the adjoining side frame parts  11 ;  12  in relation to one another. In the embodiment depicted in  FIG. 5 , the centering device  44  is embodied as a V-block device  44 , which comprises a receiving piece  46  with a V-shaped receiving opening  47 . This receiving piece  46  is preferably secured on one side frame part  11 ;  12 , such as for example, on the stationary side frame part  11 . An insertion piece  48 , with a V-shaped insertion nose  49 , is preferably secured on the other side frame part  11 ;  12 , such as, for example, on the displaceable side frame part  12 . The V-shapes of the receiving piece  46  and of the insertion piece  48  correspond with, and are complementary to one another. 
     As is shown schematically in  FIG. 2 , the centering device  44  is provided on only one side of the printing unit  01 . It is arranged on the upper end sections of the side frame parts  11 ;  12  that face one another. It may be situated above the uppermost closure device  31  or may be situated below the lowermost closure device  31 . 
     In addition, for use in defining the functional position of the two side frame parts  11 ;  12 , at least one stop device  51 , which defines such a functional position, is provided, as may be seen, for example, in  FIG. 4  or in  FIG. 10 . Preferably, multiple stop devices  51  are provided. In particular, stop devices  51  are provided on both sides of the printing unit  01 , such as, for example, on the side frame parts  11 ;  12  of both sides of the printing unit  01 . In particular, multiple stop devices  51  can be provided on each side of the printing unit  01 . For example, two such stop devices  51  can be located on each printing unit side, or three or four stop devices  51  can be located on each side, based upon the format to be printed. Each closure device  31  can preferably be assigned a stop device  51 , with each such closure device  31  preferably being assigned to its stop device  51  such that the respective stop device  51  is positioned directly adjoining the respectively assigned closure device  31 . 
     Each stop device  51  can, as is shown most clearly in  FIG. 4 , comprise two disk-shaped stop elements  52 ;  53 , for example, having surfaces that face one another and that define the stop surfaces. One stop surface is fastened to the side frame part  11  and the other stop surface is fastened to the side frame part  12 , for example by the use of suitable fasteners, such as screws which are not specifically shown. Each stop device  51  can be embodied as being adaptable or adjustable, with respect to its precise stop position. This can be accomplished, for example, in a manner which is not specified in greater detail, by inserting different numbers of spacers and/or spacers of different thicknesses at the points of attachment of each stop position  52 ;  53  to its side frame part or module  11 ;  12 . 
     To accomplish a displaceable mounting of the at least one displaceable side frame part or module  12  of the frame  02  of the printing unit  01  or of the printing tower  01 , on each side of the printing unit  01 , at least one running block assembly  54  is provided, as may be seen, for example, in  FIG. 7  through  FIG. 14 . In the embodiment shown, for example in  FIG. 3 , three running block assemblies  54  are provided on each side of the printing unit  01 . Each running block assembly  54  can be fastened with screws  56 , for example, as depicted in  FIG. 9 , on the respective underside of the two opposite side frame parts or the respectively lower side frame half  12   b  of the displaceable side frame part  12 . Opposite each of the running block assemblies  54 , on the two lateral supports  57  of the base  13 , guide rails  58  are mounted. The running block assemblies  54  run on these guide rails  58 , which, at the same time, serve to laterally guide or to adjust the movable side frame part  12  as will be described further below. 
     Each running block assembly  54  is comprised of an overall, approximately rectangular running block support  59 , as may be seen, in particular, in  FIG. 12  through  FIG. 14 . Each such running block support  59  can be fastened to the underside of the respective side frame part  12  via through holes or bores  60 , and which running block supports  59  accommodates a running block  61 , as is shown most clearly in  FIG. 11 . The running block  61  comprises a running block housing  62 , on the sides of which are formed two fixed projections  63 . These projections are formed with through holes  64  for use in fastening on the running block support  59  on the underside of the side frame part  12 . 
     In the housing  62  of the running block  61 , a plurality of rollers  66  are arranged in parallel. These rollers  66  are mounted to rotate around at least one closed track, arranged in a vertical plane which extends in the direction of movement of the displaceable side frame part  12 , as the running block  61  moves. As is clear in the depiction shown in  FIG. 11 , multiple parallel tracks for multiple groups of rotating rollers  66  can be provided in each running block  61 . Particularly as shown in  FIG. 11 , two parallel tracks, for two groups  67 ;  68  of rotating rollers  66 , are arranged side by side. The closed track can be defined, for example, in a manner which is not specified in greater detail here, by two guide grooves located in the running block housing  62  opposite one another, in which two guide grooves, axle journals of the rollers  66  are guided. 
     The housing  62  of the running block  61  is open on its underside that faces the guide rail  58 . The guide track for the rollers  66  is linear or flat in this area, thereby allowing the rollers  66  to come into contact with the guide rail  58  on their underside, and on their opposite, upper side, to be supported against a corresponding support surface which is formed in the housing  62  and which is not specified in greater detail. When the displaceable side frame part  12  moves, the components of the running block  61  and the guide rail  58  roll against one another in the manner of a roller bearing. 
     At least one stripper device  69  is assigned to each running block assembly  54 , and is arranged upstream of the rollers  66  of the running block  61 . Each such stripper device  69  is usable to scrape any soiling off of the surface of the guide rail  58  as the running block  61  moves, thereby keeping soiling away from the running block  61 . Preferably, two stripper devices  69  are provided on each running block assembly  54 , with one such stripper device  69  being arranged upstream of the running block  61  in each of the two directions of travel of the running block  61 . 
     A stripper device  69  can be arranged on the running block assembly  54 , for example, on each of the front and rear sides of the rectangular running block support  59 , as viewed in the direction of travel of the running block assembly  54 , as seen in  FIG. 14 . In this case, the stripper device  69  can be embodied as a stripper seal  69 , and can consist, for example, of flexibly deformable material with at least one stripper lip  71  which is arranged in the travel plane of the rollers  66 . For a particularly effective seal, in the preferred embodiment, each such stripper device  69  has two stripper lips  71 , such as, for example, two such sealing lips  71 , which are arranged one in front of the other, as viewed in the direction of travel of the running block  61 . 
     In addition to the above-described running block assemblies  54 , guide roller supports  72 ;  73 ;  74  are also fastened on the underside of at least one of the two displaceable side frame parts  12  that are opposite one another, or may be fastened to both displaceable side frame parts  12  that are opposite one another. Such guide roller supports  72 ;  73 ;  74  are preferably situated only on the one side frame part  12  that supports the centering device  44 . These guide roller supports are optionally embodied as being adjustable with respect to their position. Guide rollers  76 ;  77 ;  78 ;  79 , having vertically arranged rotational axes are mounted on these guide roller supports, and are supported on both sides of the guide rail  58  on its narrow side. These guide rollers  76 ;  77 ;  78 ;  79  enable a guiding or an adjustment of the movably mounted side frame part  12 . Guide roller support  72  supports a guide roller  76  arranged on the inside, guide roller support  73  supports a guide roller  77  arranged on the outside, and guide roller support  74  supports both a guide roller  78  arranged on the inside and a guide roller  79  arranged on the outside, all as seen most clearly in  FIG. 9 . 
     An alternative type of mounting, which will now be described, is an alternative to the above-described mounting of the displaceable side frame part  12  using running blocks  61 . A mounting of the displaceable side frame part  12  on sliding blocks  82 , and using this alternative type of mounting, will be described in what follows in reference to  FIG. 15  to  FIG. 22 . 
     To accomplish the displaceable mounting of the at least one displaceable side frame part or module  12  of the frame  02  of the printing unit  01  or of the printing tower  01 , a sliding block assembly  81  may be provided on each side of the printing unit  01 . Each such sliding block assembly  81  comprises at least one sliding block  82  having a sliding surface  88 , which is preferably made of plastic. In the illustrated embodiment shown in  FIG. 15 , on each side of the printing unit  01 , three sliding blocks  82  are provided, for example, which three sliding blocks  82  are held in a shared sliding block support  83 . This shared sliding block support  83  can be fastened on the respective underside of the two side frame parts that are opposite one another, or can be secured on the respective lower side frame half  12   b  of the displaceable side frame part  12 , by the use of screws  84 , for example. The sliding surface  88  can also be screwed on or glued on directly to the displaceable side frame part  12 . Opposite the sliding block assembly  81 , guide rails  58  are fastened on the two lateral supports  57  of the base  13 , along which guide rails  58  the sliding block assemblies  81  run and which guide rails  58  also serve, at the same time, for the lateral guidance and/or for the adjustment of the movable side frame part  12 , as will be described further subsequently. 
     Each sliding block  82  is held in a recess in the sliding block support  83  whisk, as seen in  FIG. 15   a  and  FIG. 16 . Each such recess in the sliding block support  83  is shaped to correspond to the shape of the sliding block  82 , and, as is shown, in particular, in  FIG. 18  through  FIG. 22 , is embodied as being at least approximately plate shaped. Each sliding block  82  has a sliding block base  86  and a sliding layer  87 , which sliding block layer  87  defines the sliding surface  88  and which sliding block layer  87  is fastened on the sliding block base  86 , such as, for example, by being glued, and, in particular, is made of plastic with low frictional properties. The sliding surface  88  of the sliding block  82 , which faces downward in its use position, projects downward beyond the underside of the sliding block support  83  when the sliding block  82  is installed. Only the sliding blocks  82 , and not the sliding block support  81 , come into contact with the surface of the guide rail  58 . 
     A suitable plastic with low frictional properties that may be used as the material for the sliding layer  87  preferably has a friction coefficient of between 0.02 and 0.40, with a surface pressure of between 1.0 and 4.0 N/mm2 and a temperature of 25° C. More specifically, the plastic has a friction coefficient of between 0.04 and 0.30, with a surface pressure of between 0.5 and 4.0 N/mm2 and a temperature of 25° C. In particular, the plastic preferably has a friction coefficient of between 0.06 and 0.12, with a surface pressure of between 0.3 and 4.7 N/mm2 and a temperature of 25° C. It is further preferable for the plastic material to have a tensile strength of between 30 and 100 N/mm2, and in particular, to have a tensile strength between 45 and 75 N/mm2. Finally, a preferable plastic material with low frictional properties has a deterioration factor, at 20° C., of less than 0.2 mm/100 km, preferably has a deterioration factor at 20° C. of less than 0.1 mm/100 km, and in particular, preferably has a deterioration factor at 20° C. of less than 0.05 mm/100 km. 
     A material that is suitable for use as the plastic material for the sliding layer  87  can especially be a structural plastic, which can preferably be embodied as a composite plastic comprising multiple materials. Such a plastic material should preferably be maintenance-free and wear-resistant. Preferably, the plastic comprises one component of thermoplastic polyester, while another component has a rubber-like character with high elasticity. A suitable material is generally known and is commercially available under the name ZEDEX, and in this case especially under the name ZX-100, preferably ZX-100A, or, in particular, Uniform 2000 gray-blue, which material possesses the preferably desirable properties to a high degree. 
     Each of the sliding blocks  82  can have a sliding surface  88  of between 20 and 1,000 cm2, for example, preferably can have a sliding surface  88  between 40 and 400 cm2, and, in particular, can have such a sliding surface  88  of 100 cm2+/−50%. In the sliding surface  88 , depressions  89 , which are usable for holding soiling, can be formed. These depressions  89  act to prevent wear and tear and to limit a decrease in sliding capacity of the sliding surface  88  caused by soiling, to the greatest possible extent. The depressions  89  can especially be embodied as grooves or flutes, and, as shown in  FIGS. 18 ,  19 ,  20  and  22 , can cover the sliding surface  88  generally in the form of a net. In particular, the longitudinal extension of the depressions  89  can run at an angle to a direction of displacement of the movable side frame part  12 , so as to enable an automatic emptying of the depressions  89 , for example. In particular, these depressions  89  form an angle of 45° with the direction of displacement of the movable side frame part  12 . It is particularly preferable for the sliding surface  88  to have a grid of intersecting, groove-shaped depressions  89 , which depressions  89  run at an angle to the direction of displacement of the side frame part  12 , as shown in  FIG. 19 , for example. 
     It is preferable for the depressions  89  of the sliding surface  88  to have a relatively large surface ratio of more than 10% of the sliding surface  88 , preferably to have a ratio of more than 20%, and in particular, to have a surface ratio of between 25% and 35% of the sliding surface  88 . In the case of the preferred embodiment, a surface ratio of 30% +/−3%, for example, of the sliding surface  88  is preferable. 
     To accomplish the lateral guidance or adjustment of the movable side frame part  12 , guide roller supports  92 ;  93 ;  94  as seen in  FIG. 17   a , and which are optionally embodied as being adjustable, with respect to their position, are attached to the underside of one or both of the displaceable side frame parts  12 . These guide roller supports  92 ;  93 ;  94  are preferably attached on only the side frame part  12  that supports the centering device  44 . Guide rollers  96 ;  97 ;  98 ;  99  are mounted on these guide roller supports  92 ;  93 ;  94 , respectively, with their rotational axes being arranged vertically, and being positioned and supported on both sides of the guide rail  58  on their narrow side, thereby enabling a guidance or an adjustment of the movably mounted side frame part  12 . Guide roller support  92  supports a single guide roller  96  arranged on the inside of guide rail  58 . Guide roller support  93  supports a single guide roller  97  arranged on the outside of guide rail  58 . Guide roller support  94  supports both a guide roller  98  arranged on the inside of guide rail  58  and a guide roller  99  arranged on the outside of guide roller  58 . 
     While preferred embodiments of a printing unit comprising at least two side frame parts whose distance relative to each other can be modified in a horizontal direction have been described fully and completely herein above, it will be apparent to one of skill in the art that changes to, for example, the specific structure of the printing groups, the numbers of printing groups in each printing unit, the source of the pressurizing 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.