Abstract:
A printing unit of a printing press is comprised of at least two frame parts, the position of at least one of which, relative to the other, can be changed. Cooperating ones of these frame parts are placed against each other along a common joining surface, in a first operational position. These frame parts are separated from each other in a second operational position. An interstice, that is partly defined by these frame parts, is formed between the separated frame parts in the printing unit. At least one of the cooperating frame parts is supported so that it is movable along an adjustment path. At least one sensor is provided and is usable to monitor the interstice. The sensor has orientation characteristics or a sensory range along the joining surface. An aperture width of a first angular aperture of the orientation characteristics or of the sensory range is smaller than a respective aperture width of a second or third angular aperture of the orientation characteristic or sensory range. The aperture width of the first angular aperture of the orientation characteristic or the sensory range is oriented parallel to the adjustment path of the movable frame path. The aperture width of the second angular aperture of the orientation characteristic or the sensory range is oriented in an axial direction of at least one printing group cylinder which is mounted on the movable frame panel. An aperture width of the third angular aperture of the orientation characteristic or the sensory range is oriented in the direction of a height of the movable frame panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national phase, under 35 U.S.C. 371, of PCT/EP2009/060651, filed Aug. 18, 2009, published as WO 2010/026041 A1 on Mar. 11, 2010, and claiming priority to DE 10 2008 041 847.1, filed Sep. 5, 2008, the disclosures of which are expressly incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a printing unit of a printing press comprising at least two frame parts, the position of which relative to one another can be changed. Interacting frame parts are placed against each other along a shared joining surface in a first operating position and are moved away from each other in a second operating position. Between the frame parts, that are moved away from each other in the printing unit, an intermediate space is formed. This intermediate space is delimited, in part, by the frame parts. At least one of the frame parts is movable along an adjustment path. 
     BACKGROUND OF THE INVENTION 
     WO 95/24314 A1 and WO 2005/037 553 A1 each describe a printing unit of a printing press comprising at least two frame parts, the position of which relative to one another can be changed, wherein interacting frame parts are placed against one another in a first operating position, and are moved away from one another in a second operating position, wherein between frame parts that have been moved away from one another, an intermediate space, delimited in part by said frame parts, is formed in the printing unit, wherein at least one printing couple cylinder is mounted in each of the respectively interacting frame parts. 
     EP 1 790 474 A1 describes a printing press comprising a printing unit with one stationary frame part and at least one frame part that is movable along a linear adjustment path, wherein the stationary frame part has at least one printing couple, wherein at least one inking unit is arranged in the movable frame part, wherein in a first operating position interacting frame parts are placed against one another and in a second operating position said parts are moved away from one another, wherein between frame parts that have been moved away from one another, an intermediate space, delimited in part by said frame parts, is formed, wherein a safety apparatus is provided, which uses a detection device disposed on the movable frame part to detect the presence of an obstacle in the adjustment path of said movable frame part. 
     EP 0 444 227 A1 describes a printing press comprising a printing unit having at least two frame parts, the position of which relative to one another can be changed, wherein printing couple cylinders are arranged in a stationary frame part, and at least one inking unit is arranged in the at least one movable frame part, wherein in a first operating position, interacting frame parts are placed against one another and in a second operating position said frame parts are moved away from one another, wherein between frame parts that have been moved away from one another, an intermediate space, delimited in part by said frame parts, is formed in the printing unit, wherein mat switches are provided, which prevent the printing couple cylinders from rotating, for example, when a person steps on one of said mat switches while the frame parts are in the operating position in which they are moved away from one another. 
     DE 102 24 031 B3 describes a device for monitoring a scanning zone of a working apparatus, said device comprising at least one redundant camera system consisting of two cameras and a beam splitter positioned upstream thereof, via which images of the scanning zone can be displayed on both cameras for detecting objects that may pose a safety risk within at least one safety zone, and comprising two computer units, wherein each computer unit is connected to one of the cameras for evaluating the image data acquired there, and wherein the two computer units are coupled to one another for the purpose of mutual verification, and comprising at least one switch output actuated by the computer units, via which output the working apparatus is placed in operation only if no object that may pose a safety risk is found within the safety zone. 
     DE 10 2004 037 888 A1 describes a printing unit of a web-fed rotary printing press, which comprises two frame sections, mounted so as to be movable in relation to one another, each having at least one printing couple with at least two interacting printing couple cylinders, wherein the printing couple cylinders are mounted with each cylinder end disposed in a bearing unit having at least one actuator, wherein each printing couple cylinder can be radially displaced in its respective bearing unit by means of the actuator, wherein the actuator is embodied as an adjustment means which is actuable via a pressurized medium, such as oil. 
     DE 200 11 699 U1 describes a printing press with an impression cylinder and at least one printing couple assigned to said cylinder, which printing couple comprises at least two bearings with socket-type supports for the interchangeable installation of tubular printing equipment parts, and an inking unit, wherein the bearing and the inking unit are supported so as to be displaceable with respect to their distance from the impression cylinder along at least one guide rail, and wherein the socket-type supports of the bearing can optionally be loaded with a selection of equipment parts on the basis of the printing technique and/or printing format, wherein the bearing and the inking unit are displaceable between an operational position, a switching position and an off-line position, wherein the bearing and the inking unit are displaceable on the guide rails, embodied as toothed racks, by means of an allocated servo motor, for displacement to the respective operational position, switching position and off-line position. 
     U.S. Pat. No. 5,025,726 A describes a printing unit of a rotary printing press having two frame sections, one of which is movable in relation to the other, wherein a locking system is provided. 
     FR 2 648 506 A1 describes a variable-width safety barrier for blocking off a hazardous area. 
     The documentation of the SICK AG company in D-79183 Waldkirch, Germany, describes safety laser scanners, product number 8010739, and the use thereof, wherein the publication date of said documentation is listed as 1 Apr. 2006. 
     SUMMARY OF THE INVENTION 
     The problem addressed by the invention is that of devising a printing unit for a printing press, comprising at least two frame parts, the position of which relative to one another can be changed, wherein a hazard posed by at least one moved frame part of said printing unit to a press operator working in the hazardous area of said printing unit is prevented. 
     The problem is solved according to the invention by a printing unit having at least one sensor that is usable for monitoring the intermediate space between the frame parts. This sensor has a directional characteristic effective along the joining surface or has a sensing zone effective along the joining surface. A field width of a first angular field of the directional characteristic or of the sensing zone, and which width is oriented parallel to the adjustment path of a movable frame part, is smaller than a respective field width of a second or third angular field of the directional characteristic or sensing zone. The field width of the second angular field of the directional characteristic or the sensing zone is oriented in the axial direction of at least one printed couple cylinder that is mounted in the movable frame part. The field width of the third angular field of the directional characteristic or the sensing zone is oriented in the direction of a height of the movable frame part. 
     The benefits to be achieved by the invention consist particularly in that the printing unit offers a high level of operational safety. In particular, the printing unit has a safety device which helps to prevent a hazard posed by at least one moved frame part of said printing unit to a press operator working in a hazardous area of said printing unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiment examples of the invention are illustrated in the drawings and are described in greater detail in what follows. 
       The drawings show: 
         FIG. 1  a printing unit comprising two frame parts, the position of which relative to one another can be changed, in a first operating position; 
         FIG. 2  the printing unit of  FIG. 1 , with its frame parts in a second operating position; 
         FIG. 3  a block diagram; 
         FIG. 4  variants for monitoring the intermediate space formed between frame parts of the printing unit, and variants of an access control device; 
         FIG. 5  another variant of the access control device. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1 and 2  each illustrate, by way of example, a printing unit  01 , embodied as a tower, particularly as an eight-couple tower, enclosed inside a frame  12  embodied, for example, as a structural framework, for a rotary printing press, which is preferably usable for color newspaper printing, wherein the printing unit  01  is highly compact in configuration, i.e., particularly having a low structural height. Two eight-couple towers of this type may also be placed one on top of the other to form a printing unit  01  embodied as a 16-couple tower. A preferably web-type print substrate  02 , for example, a paper web  02 , to be imprinted in the printing unit  01  is preferably guided substantially vertically through the printing unit  01 . Preferably a plurality of printing couples  03  are arranged preferably on each side of the paper web  02 , wherein each of said printing couples  03  has at least one printing couple cylinder  04 , particularly transfer cylinder  04 , and preferably one forme cylinder  06 , which interacts with the transfer cylinder  04 . Each printing couple  03  is also equipped with a preferably keyless inking unit  07  having multiple rollers, for example, an anilox inking unit  07  having a screen roller, wherein the rollers of the inking unit  07  draw ink from an ink reservoir  09  and form it into a thin ink film, evening out the thickness of said ink film, and transport said film to the respective forme cylinder  06  for the purpose of applying it to at least one printing forme arranged on the forme cylinder  06 . The respective forme cylinder  06  of each of the printing couples  03  has an axial length of between 1,000 mm and 4,000 mm, for example, preferably between 1,200 mm and 2,600 mm, particularly between 1,600 mm and 2,100 mm, and preferably holds a plurality of printing formes, for example, four or six, side by side in its axial direction, wherein the respective subject of each printing forme is assigned to a specific page of the printed product to be produced by the rotary printing press, for example, a newspaper. The axial length of the transfer cylinder  04  is adapted to the respective forme cylinder  06  that interacts with it. The transfer cylinder  04  and the respective forme cylinder  06  can have the same circumference ( FIGS. 1 and 2 ), or the circumferential length of the forme cylinder  06  is about one-half the size of the assigned transfer cylinder  04 . The rotary printing press illustrated by way of example in  FIGS. 1 and 2  prints, for example, in an offset printing process, preferably in a dry offset printing process, i.e., in an offset printing process that does not use a dampening agent, therefore the printing couples  03  depicted in  FIGS. 1 and 2  do not have dampening units. 
     In the preferred embodiment, at least one, and particularly each, of the printing couples  03  of the printing unit  01  has a printing forme magazine  08 , wherein each respective printing forme magazine  08  is assigned to the forme cylinder  06  of the respective printing couple  03 . Each printing forme magazine  08  has at least one storage position for storing at least one printing forme, wherein each storage position is preferably embodied in a chute or as a chute, wherein said chute preferably has a transport device, for example, remotely actuable, for supplying at least one new printing forme to the forme cylinder  06 . Each printing forme magazine  08  preferably also has a chute with an also preferably remotely actuable transport device for removing at least one used printing forme from the forme cylinder  06 . 
     The printing formes are each fastened to the respective forme cylinder  06  by means of a retaining device, for example, a clamping device, preferably remotely actuable, arranged in the respective forme cylinder  06 . The retaining device is embodied as pneumatically actuable, for example, and is arranged in a groove  11  in the respective forme cylinder  06 , wherein said groove  11  extends in the axial direction of the relevant forme cylinder  06 . 
     The frame  12  of the printing unit  01  consists, for example, of one lower and one upper support, each arranged horizontally, and, for example, two side frames, preferably arranged vertically between these two supports, wherein supports and side frames together form a frame, for example, which holds the printing unit  01 , preferably encompassing it. The lower support can be embodied to act as the preferably substantially rectangular base plate of the printing unit  01 , whereas the upper support forms a cover plate for the printing unit  01 , for example. The printing unit  01  encompassed by said frame  12  has at least two frame parts  13 ;  14 , the position of which relative to one another can be changed, wherein one of said frame parts  13  is preferably embodied as stationary in the shared frame  12  (in  FIGS. 1 and 2 , the left frame part  13 , for example), whereas at least one other frame part  14  that interacts with the stationary frame part  13  (in  FIGS. 1 and 2 , the right frame part  14 , for example) is arranged in the shared frame  12  so as to be movable, particularly positionable, bidirectionally, for example, parallel to the lower and upper supports, along a preferably linear adjustment path S between two end points that delimit the adjustment path. Because at least one of the interacting frame parts  13 ;  14 , which have a substantially rectangular base surface, is movable, the frame parts  13 ;  14  have two different operating positions, wherein in a first operating position the frame parts  13 ;  14  are placed against one another along a shared joining surface  16  which extends across the height H and width B of the printing unit  01  ( FIGS. 1 ,  2  and  4 ), and in a second operating position, the frame parts are moved away from one another ( FIG. 2 ). The second operating position of the movable frame part  14  is indicated by dashed lines in  FIG. 2 . The shared joining surface  16  between the interacting frame parts  13 ;  14  is illustrated in  FIG. 1  by way of example as two cut-outs. In a first operating position, the frame parts  13 ;  14 , the position of which relative to one another can be changed, are placed directly against one another, with no intermediate space  17 , wherein in this first operating position, the at least one movable frame part  14  can be locked in position, at least at the relevant end point of the adjustment path S, preferably via remote actuation, to prevent it from moving unintentionally. The joining surface  16  between frame parts  13 ;  14  placed against one another, formed in the first operating position, coincides, for example, with a transport plane of the paper web  02 , which is preferably guided vertically through the printing unit  01 . In the second operating position, the interacting frame parts  13 ;  14 , the position of which relative to one another can be changed, are moved away from one another such that their respective sides that face the paper web  02  being guided through the printing unit  01  are opposite one another in parallel. During the changeover from the first operating position to the second operating position, the width of the preferably rectangular-shaped intermediate space  17  present between the interacting frame parts  13 ;  14  can be changed between a minimal value, preferably zero, and a maximum value of 1 m to 2 m, for example. 
     At least one printing couple cylinder  04 , particularly embodied as transfer cylinder  04 , is mounted in each of the interacting frame parts  13 ;  14 , wherein when the interacting frame parts  13 ;  14  are in the first operating position, the at least one printing couple cylinder  04 , mounted in the frame part  13  which is stationarily positioned in the frame  12 , for example, can be placed against the at least one printing couple cylinder  04  mounted in the other frame part  14  which is movably positioned in the frame  12 , for example, thereby forming a shared print position that imprints the paper web  02  particularly on both sides. In the second operating position, in which the two frame parts  13 ;  14 , the position of which relative to one another can be changed, are moved away from one another, an intermediate space  17 , delimited in part by the frame parts  13 ;  14 , is formed between these two frame parts  13 ;  14  in the printing unit  01 , particularly within the structural frame thereof, wherein said intermediate space  17  is then freely accessible and passable to press operators of the printing unit  01 , at least when the frame part  14  which is movably arranged in the frame  12  has reached the end point at which it is the maximum distance from the joining surface  16  formed with the stationary frame part  13  ( FIG. 2 ). The at least one movable frame part  14  can also be locked in place in its second operating position, particularly at the relevant end point of the adjustment path S, to prevent it from moving unintentionally. In the preferred embodiment, a plurality of printing couples  03 , particularly four, are arranged in each of the interacting frame parts  13 ;  14 . Each of the interacting frame parts  13 ;  14 , particularly movable frame part  14 , has a mass of 30 tons or more, for example. 
     On one operating side  21  of at least one of the frame parts  13 ;  14 , a height-adjustable operator&#39;s platform  22  is arranged, for example, to facilitate access by press operators working on the printing unit  01  to the upper printing couples  03  of the printing unit  01 . The operating side  21  of the respective frame part  13 ;  14  is located on the side thereof that faces away from the transport plane of the paper web  02  being guided through the printing unit  01 . Additionally or alternatively, a height-adjustable operator&#39;s platform  22  that can also be lowered into the base plate is also arranged, for example, in the intermediate space  17  which is delimited in part by the interacting frame parts  13 ;  14 . 
     To allow the movable frame part  14  to be moved, said part is mounted, for example, in a linear bearing and/or is guided in such a bearing as it is being moved. For implementing the movement of the frame parts  13 ;  14 , the position of which relative to one another can be changed, at least one drive unit  23  is provided, which is assigned to at least one of the interacting frame parts  13 ;  14  to change it from one operating position to the other operating position. As was described above, at least one printing couple cylinder  04  is mounted in each of the interacting frame parts  13 ;  14 , wherein at least a second drive unit  24  is provided for implementing a radial movement of the respective printing couple cylinder  04 , wherein the radial movement of the respective printing couple cylinder  04  particularly has an orthogonal component relative to the joining surface  16  of the frame parts  13 ;  14 . The printing couple cylinders  04  arranged in the same frame part  13 ;  14  can be moved radially by the respective second drive unit  24 , all together, or each selected individually. 
     Each of the drive units  23 ;  24  has, for example, at least one operating cylinder that can be acted on by a pressurized medium, wherein to reduce energy costs, both drive units  23 ;  24  and preferably also a locking system  26  for latching or locking the relevant movable frame parts  13 ;  14  in place in their respective operating positions, i.e., particularly at the respective end points of the relevant adjustment path S, are preferably supplied with power, for example pressurized hydraulic fluid, from a shared energy storage device  27 , particularly from the same hydraulic unit  27 , so that only a single conduit system  19  is required for supplying power to the two drive units  23 ;  24 , and if applicable to the locking system  26 , in the printing unit  01  ( FIG. 3 ). The hydraulic unit  27  has, for example, a compressor or a pump. The supply of power to at least one of the two drive units  23 ;  24  and to the locking system  26  can preferably be remotely actuated, for example, from a preferably electronic control unit  28 , particularly from a control center  28  belonging to the printing unit  01 , wherein the two drive units  23 ;  24  and the locking system  26  can each be actuated individually and independently of one another. The hydraulic unit  27  pressurizes the operating cylinder of the drive units  23 ;  24  with a pressure of, for example, 100 bar to 500 bar. The functional units connected to the same hydraulic unit  27  as the two drive units  23 ;  24  and the locking system  26  are switched to pressureless or pressurized, for example, by means of the same controllable control element  34 , for example, valve  34 , which is particularly controlled by the control unit  28 , wherein said valve  34  is assigned directly to the output of the hydraulic unit  27  and is arranged upstream of a branch of the conduit system  19  that distributes the pressure to connected functional units, so that the respective functional position of the control element  34  affects all elements supplied with pressure from the hydraulic unit  27  ( FIG. 3 ). 
     Because the intermediate space  17  that is formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed, in the second operating position thereof allows access, preferably even full-body access, to press operators working with the printing unit  01 , in order to protect a press operator who might enter the intermediate space  17  or might reach into the intermediate space  17  with one of his body parts, a safety device  18  is provided in or on the printing unit  01  ( FIG. 3 ), to prevent bodily injury, particularly crushing injuries, that could occur when the movable frame part  14  is placed in motion by the first drive unit  23 , which is activated by the control unit  28 , for example, particularly automatically, i.e., in a program-controlled system. The safety device  18  has, for example, at least one additional control element  29 , for example, valve  29 , also arranged in the system for supplying power for actuating the first drive unit  23 , and controlled separately by the control unit  28 , for example, with said valve having a functional position that can be selected by the control unit  28 , in which position, for example, in the event of a malfunction occurring in the conduit system  19  for supplying power, for example, in the case of a circuit malfunction, relative movement between the frame parts  13 ;  14  is prevented, i.e., the movable frame part  14  is prevented from moving, for example, toward the stationary frame part  13 , which could endanger a press operator working in the intermediate space  17  between the frame parts  13 ;  14 , the position of which relative to one another can be changed. The selected functional position of this control element  29 , which is particularly controlled by the control unit  28  separately and independently from the control of the first drive unit  23 , affects only the operability of the first drive unit  23 . In order for the first drive unit  23  to be operable, the supply of pressurized medium to it must be enabled by the control element  29 , which is preferably controlled directly by the control unit  28 . If this supply of pressurized medium is prevented or withdrawn by the control element  29 , the first drive unit  23  is not operable, irrespective of the commands from its selection. 
     The safety device  18  preferably also has at least one detection device  31 , particularly a sensor  31 , for example, attached to the movable frame part  14 , which sensor detects and monitors, in a contactless manner, the presence and/or movement of a body that does not belong to the printing unit  01 , i.e., particularly the presence and/or movement of a person, in the intermediate space  17 , preferably embodied as rectangular-shaped and having a variable width, between the frame parts  13 ;  14 , the position of which relative to one another can be changed. The sensor  31  preferably works with electromagnetic waves, for example, with light or microwaves (radar system), or ultrasonic waves, and is embodied, for example, as a video camera suitable for monitoring a room, or as a motion detector, wherein the motion detector is embodied, for example, as a passive infrared detector. The sensor  31 , embodied as a camera or as a motion detector, can be attached, for example, in or on the upper support of the frame  12 , which is embodied as a cover plate. Another variant provides that particularly the sensor  31 , embodied as a camera or as a motion detector, is preferably permanently affixed to the movable frame part  14 , for example, by means of a support arm  36  that is attached to said frame part  14  and supports the sensor  31 , wherein the sensing zone  37  of the sensor  31  is directed into the intermediate space  17  ( FIG. 2 ). The sensor  31  is connected to the control unit  28 , particularly to the control center  28  belonging to the printing unit  01 , at least for purposes of data transfer. As soon as the sensor  31  detects the presence and/or movement of a person in the intermediate space  17 , while the first drive unit  23  that drives the movable frame part  14  is actuated, the movement of the first drive unit  23  is immediately halted via the control element  29  acting on said drive unit  23 , and the direction of movement of the frame part is optionally reversed. When a person is detected in the hazardous area, for example, the movable frame part  14  can be brought to a halt almost instantaneously, within an adjustment path S of fewer than 5 mm, for example, by an actuation of at least one of the control elements  29 ;  34  by switching off the first drive unit  23 , i.e., switching it to pressureless, and/or by activating a brake device actuated by the control unit  28 . 
       FIG. 3  illustrates, by way of example in a block diagram, the interaction of the at least one sensor  31 , the control unit  28 , the control elements  29 ;  34 , the energy storage device  27 , the drive units  23 ;  24  and the locking system  26 , wherein the respective direction of action is indicated in each case by an arrow, wherein particularly the sensor  31  and the control element  29  arranged in the conduit system  19  to the first drive unit  23  are assigned to the safety device  18 . The control unit  28  verifies the functional readiness and/or functionality of the sensor  31 , preferably on a continuous basis. If the sensor  31  is not functionally ready and/or functional, the control unit  28  will prevent a release for initiating a movement of the movable frame part  14 , or the control unit  28  will stop the first drive unit  23  that drives the movable frame part  14  by issuing a corresponding control command, for example, to the valve  34  assigned to the energy storage unit  27  and/or to the energy storage unit  27  itself, wherein the latter variant is indicated in  FIG. 3  by a dashed directional arrow. If the sensor  31  is not functionally ready and/or functional, alternatively or in addition to controlling the first drive unit  23  and/or at least one of the control elements  29 ;  34 , the control unit  28  can then actuate the locking system  26  that locks the movable frame part  14  in place. 
       FIGS. 4 and 5  each show, in a simplified illustration, a plan view of the printing unit  01  depicted in  FIGS. 1 and 2 , with the frame parts  13 ;  14 , the position of which relative to one another can be changed within the frame  12 . 
     In one advantageous embodiment, the at least one sensor  31 , which monitors the intermediate space  17  between the frame parts  13 ;  14 , the position of which relative to one another can be changed, has a directional characteristic  32  along the joining surface  16  of said frame parts, for example, which characteristic extends like a curtain within the intermediate space  17 , preferably a very short distance a, in the range of a few millimeters to at most a few centimeters, for example, particularly in front of the movable frame part  14 , wherein a field width w of a first angular field of the directional characteristic  32  or of the sensing zone  37  of the sensor  31 , said width being directed parallel to the adjustment path S of the movable frame part  14 , is preferably much smaller than a field width u; v, orthogonal thereto, of a second and/or third angular field of said directional characteristic  32  or said sensing zone  37 , wherein the field width u of the second angular field of the directional characteristic  32  is oriented in the axial direction of the at least one printing couple cylinder  04  mounted in the movable frame part  14  ( FIG. 4 ), and the field width v of the third angular field of the directional characteristic  32  or the sensing zone  37  is oriented in the direction of a height H of the movable frame part  14  ( FIG. 2 ). The directional characteristic  32  or the sensing zone  37  are therefore heavily concentrated at least in a direction in space which is opposite at least one of the two other orthogonal directions in space, and therefore the directional characteristic  32  or the sensing zone  37  preferably extends flat along the joining surface  16  of the movable frame part  14 . The field width u of the second angular field of the directional characteristic  32  or the sensing zone  37 , which width is oriented in the axial direction of the at least one printing couple cylinder  04 , and/or the field width v of the third angular field of the directional characteristic  32  or the sensing zone  37 , which width is oriented in the direction of the height H of the movable frame part  14 , can each be widened using an optical system, for example, particularly a system of lenses. The second angular field of the directional characteristic  32  or of the sensing zone  37 , which angle is oriented in the axial direction of the at least one printing couple cylinder  04  mounted in the movable frame part  14 , can be opened up to the height H of said frame part  14 , and the third angular field of the directional characteristic  32  or of the sensing zone  37 , oriented in the direction of the height H of the movable frame part  14 , can be opened over an entire width B of the movable frame part  14 , said width extending in the axial direction of the printing couple cylinder  04  mounted in the movable frame part  14  ( FIG. 4 ). In  FIG. 4 , which provides a plan view of the printing unit  01 , in the interest of clarity, the at least one printing couple cylinder  04  with its rotational axis indicated is shown in only one frame part, namely the stationary frame part  13 , even though at least one printing couple cylinder  04  is also mounted in the movable frame part  14  (see  FIG. 2 ). 
     In another variant, the at least one sensor  31  that monitors the intermediate space  17  is arranged so as to pivot, so that the sensing zone  37  of the sensor  31 , which in this variant is preferably embodied as beam-shaped and therefore narrow, extends along the joining surface  16  formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed, as a result of a preferably periodic pivoting movement of said sensor  31 , wherein in this variant, the sensor  31  is preferably embodied as at least one laser, wherein the laser emits a beam having a narrow diameter of, for example, fewer than 2 mm, and scans a scanning zone defined by the pivoting movement of said sensor  31 . Therefore, irrespective of the practical embodiment of the sensor  31 , the sensing zone  37  of said sensor  31  can execute a pivoting movement, wherein the sensing zone  37  extends along the joining surface  16  formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed. 
     It is also advantageous to provide that the control unit  28  which is connected to the sensor  31  activates and/or evaluates the signals from the at least one sensor  31  that monitors the intermediate space  17 , which is preferably embodied as rectangular in shape and particularly having a variable width, on the basis of the operating positions of the interacting frame parts  13 ;  14 . In this case it is particularly provided that, when the frame parts  13 ;  14 , the position of which relative to one another can be changed, are moving toward one another, the control unit  28  switches the sensor  31  to mute once a predefined distance x between said frame parts  13 ;  14  is reached, i.e., that the control unit  28  does not evaluate the sensor&#39;s signal elicited by the detection of a frame part  13 ;  14  as a malfunction, and therefore also does not halt the movement of the frame parts  13 ;  14 , the position of which relative to one another can be changed. The distance x at which the control unit  28  switches the sensor  31  to mute is selected to be greater than a field width w of the directional characteristic  32  or of the sensing zone  37  of the sensor  31 , wherein said field width w is oriented parallel to the adjustment path S of the frame parts  13 ;  14 , the position of which relative to one another can be changed. Switching the sensor  31  to mute can alternatively or additionally be time-dependent, particularly dependent on a duration of the movement carried out by at least one of the frame parts  13 ;  14 , the position of which relative to one another can be changed. In its active time, during which it is switched on, the sensor  31  monitors the intermediate space  17  preferably continuously, with its directional characteristic  32  or its sensing zone  37 . 
     Because once the sensor  31  has been switched to mute there is a danger that the movement of the frame parts  13 ;  14 , the position of which relative to one another can be changed, toward one another in the intermediate space  17  might cause injury to a press operator, for example, to his limbs if these are reaching into the intermediate space  17 , the safety device  18  is preferably expanded to include additional components, wherein the control device  28  activates these additional components either no earlier than the start of movement of the frame parts  13 ;  14 , the position of which relative to one another can be changed, and/or no later than simultaneously with the switching of the sensor  31  to mute. These additional components connected to the control unit  28  consist preferably of an access control device  33  ( FIG. 3 ), which controls at least one access point, for example, formed on a longitudinal side of the printing unit  01 , to the intermediate space  17  that remains once the sensor  31  has been switched to mute. 
     The access control device  33  can have one or more photoelectric beam detectors or one or more infrared beam barriers, for example, wherein the respective beam paths of the photoelectric beam detectors or infrared beam barriers are oriented horizontally or vertically, for example. The access control device  33  can perform a control function, for example, over the entire height H of at least the movable frame part  14 , or over only one or more portions of this height H. 
     The access control device  33  can have a scanner  38 , arranged, for example, near the base plate, for example, at a height h of up to 200 mm, preferably about 100 mm, which therefore acts in the floor area of the intermediate space  17 , wherein the sensing zone  37  of said scanner  38  is oriented substantially parallel to the longitudinal side of the printing unit  01 , wherein at least one length l of said sensing zone  37 , oriented parallel to the longitudinal side of the printing unit  01 , can preferably be adjusted to variable lengths in the control unit  28 , wherein said variable length l is adjustable and adjusted particularly on the basis of the distance x formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed ( FIG. 2 ). The distance x ranges, for example, up to 2,000 mm. The base plate of the intermediate space  17  formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed, can also be covered by a pressure sensor mat (not shown), which sends a signal to the control unit  28  when the pressure sensor mat detects the presence of a person in the intermediate space  17  on the basis of the contact of that person with the base. 
     An additional or alternative embodiment of the access control device  33  can consist, for example, of at least one sensor strip  39 , consisting of multiple sensors  41  arranged in a row, and particularly attached to the upper support of the frame  12 , with each such strip monitoring one of the access points, formed on a longitudinal side of the printing unit  01 , to the intermediate space  17  that is formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed, with said monitoring involving sensing by means of a barrier, for example, a multiple infrared beam barrier, preferably of narrow mesh, and generated, for example, by the sensors  41  in the respective sensor strip  39 . The individual sensors  41  of the respective sensor strip  39  can preferably be activated and/or deactivated on the basis of the distance x that is formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed, such that the control unit  28  will evaluate only the signal of those sensors  41  of the sensor strip  39  which are active at a given point in time for the variable-width access point to the intermediate space  17 . All the sensors  41  of the respective sensor strip  39  are switched off, for example, only when the printing unit  01  is in a printing process. As described above, each of the sensors  41  can be embodied as a camera or as a motion detector or as a laser or as a radar system. 
     As shown in  FIG. 5 , additionally or alternatively to one of the aforementioned variants, the access control device  33  can also have a mechanical safety barrier  42  on at least one of the longitudinal sides of the printing unit  01 , wherein said safety barrier  42  is embodied, for example, in the form of a sliding door, wherein said sliding door, attached to one of the frame parts  13 ;  14 , for example, mounted in a rail, can be displaced lengthwise along the longitudinal side of the printing unit  01 , at least on the basis of the movement of the frame parts  13 ;  14 , the position of which relative to one another can be changed, wherein the direction of movement of the safety barrier is indicated in  FIG. 5  by a double arrow. Thus the safety barrier  42 , in its operating state in which it blocks access to the intermediate space  17 , is embodied as having a variable width between the frame parts  13 ;  14 , the position of which relative to one another can be changed. When access to the intermediate space  17  between the frame parts  13 ;  14 , the position of which relative to one another can be changed, and which have been moved away from one another is to be blocked, the sliding door attached to one of the frame parts  13 ;  14  is connected to the respectively other frame part  13 ;  14 , in that the sliding door is suspended from said part in a lock  43 . The lock  43  has an electrical contact switch, for example, which sends a signal to the control unit  28  reporting the blocking of the relevant access to the intermediate space  17  between the frame parts  13 ;  14 , the position of which relative to one another can be changed, and which have been moved away from one another. Then, a probing device  44 , for example, a sliding element  44 , which can preferably be lowered into and raised out of the base plate of the printing unit  01 , can be erected at least in the floor area of the intermediate space  17  and moved through the intermediate space  17  along the width B of the printing unit  01 , as indicated in  FIG. 5  by a motion arrow, in order to verify that no person or other object, such as a tool or similar object that may have been left behind, is still present in the intermediate space  17  after the safety barrier  42  has been activated. On the side of the sliding element  44  that is directed into the intermediate space  17  at least one contact switch  46  is provided, for example, which is capable of detecting contact with a person or with an object still present in the intermediate space  17 . Alternatively, this verification can also be performed in a contactless manner, for example, using optical means, for example, with the sensor  31  embodied as a camera. Once it has been verified that no persons or objects are present in the intermediate space  17 , a release signal is sent to the control unit  28 , whereupon the control unit  28  actuates the first drive unit  23 , whereby the frame parts  13 ;  14 , the position of which relative to one another can be changed, and which have been moved away from one another, are moved toward one another along their adjustment path S, thereby reducing the width of the intermediate space  17  to its minimal value, preferably to zero. The control element  29  arranged in the conduit system  19  for supplying power to the first drive unit  23  can also be controlled by the control unit  28  on the basis of the signal from the probing device  44  that monitors the intermediate space  17  and/or from the safety barrier  42 . 
     The access control device  33  can be permanently or only temporarily present at the respective access point to the intermediate space  17 . At least a part of the access control device  33  can have an off-line position and an operational position, wherein in the off-line position, the corresponding part of the access control device  33  is mechanically covered or moved into a protected position, in order to protect it against soiling or damage. The at least one sensor  31  for monitoring the intermediate space  17  and the access control device  33  are activated by the control unit  28 , for example, alternatingly, on the basis of the respective operating position of at least the movable frame part  14 . As was described above, the control unit  28  immediately halts the movement of the movable frame part  14  when the sensor  31  and/or the access control device  33  detect the presence and/or movement of a body not belonging to the printing unit  01 , particularly a press operator, present in a hazardous area of the printing unit  01  which has been created by a movement of the movable frame part  14 . 
     A further improvement of the safety device  18  consists in locating a warning area  47  in front of the intermediate space  17  formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed, which space is monitored by the at least one sensor  31 , wherein the warning area  47 , which extends particularly along the longitudinal side of the printing unit  01 , is scanned either by a sensor  48  provided especially for this purpose ( FIG. 4 ) and/or by the sensor  31  that monitors the intermediate space  17 , wherein in this case the scanning zone  37  of the sensor  31  that monitors the intermediate space  17  overlaps with the intermediate space  17 . On the basis of the presence and/or movement within the warning area  47  of a body not belonging to the printing unit  01  while the frame parts  13 ;  14  are interacting, the control unit  28 , which is connected to at least one of the sensors  31 ;  48 , will activate a switchover from one operating position of the frame parts to the other, or will halt a movement that has already begun, in the event of a potential hazard. Monitoring the warning area  47  allows the control unit  28  to cause the safety device  18  and/or the drive units  23 ;  24  and/or the locking system  26  to react quickly when a person approaches the printing unit  01  or at least one of the moving frame parts  13 ;  14  in a manner that could cause harm to that person. Like the sensor  31  that monitors the intermediate space  17 , the sensor  48  specifically for monitoring the warning area  47  is embodied, for example, as a camera or as a motion detector or as a laser or as a radar system, and works, for example, with electromagnetic waves, for example, light or radar, or ultrasonic waves. The sensor  48  that monitors the warning area  47  can have a directional characteristic  32  or a sensing zone  37  having a substantially oval or elliptical cross-section, with which it monitors the warning area  47  in front of the intermediate space  17  formed between the frame parts  13 ;  14 , the position of which relative to one another can be changed. 
     A further embodiment of the sensor  48  that monitors the warning area  47  can consist of an arrangement of at least one of the sensors  48  that projects into the warning area  47 , wherein preferably a plurality of said sensors  48  are arranged particularly close to one another in a row. The sensor  48  is preferably arranged on the movable frame part  14 , for example, in the area of the cover plate belonging to said frame part  14 , wherein the directional characteristic  32  or the sensing zone  37  of this sensor  48  is oriented particularly vertically downward, such that said sensor  48  will detect a person or an object moving on the side of the movable frame part  14  that faces the intermediate space  17 , through the access point to said intermediate space  17  that extends longitudinally along the printing unit  01 , and into said space ( FIG. 4 ). A mesh width m between the respective directional characteristic  32  or the respective sensing zone  37  of sensors  48  that monitor the same warning area  47  is only a few millimeters, for example, particularly fewer than 20 mm, preferably from 8 mm to 15 mm. The sensor  48  for monitoring a warning area  47  is positioned at a distance y of fewer than 20 mm, for example, preferably from 8 mm to 15 mm, from an edge  49  of the movable frame part  14 , which edge extends vertically, for example, and is formed on the joining surface  16 . The depth t of the warning area  47 , referred to the longitudinal side of the printing unit  01 , and extending in the direction of its width B, is 500 mm to 1,000 mm, for example. 
     The aforementioned embodiments for monitoring the intermediate space  17  and/or the warning area  47  can also be combined with one another. For example, at least on one side of one of the interacting frame parts  13 ;  14 , a barrier  51  (indicated by dashed lines in  FIG. 4 ) can be permanently or temporarily attached, extending widthwise from said frame part, to which barrier, in turn, a mechanical or contactless safety barrier  42 , according to the above-described examples, is arranged, at a lateral distance z from the relevant longitudinal side of the printing unit  01 . The distance z corresponds, for example, to the depth t of the warning area  47 . 
     While a preferred embodiment of a printing unit of a printing press comprising at least two frame parts, the position of which relative to one another can be changed, has been described fully and completely hereinabove, it will be apparent to one of skill in the art that various changes, for example, in the specific structure of the printing unit components, the types of materials being printed on, the drives for the printing unit components, and the like could be made without deviating from the spirit and scope of the present invention which is accordingly to be limited only by the appended claims.