Patent Publication Number: US-6705610-B2

Title: Arrangement for sheet holder systems on storage drums in turning devices of sheet-fed printing machines

Description:
The invention relates to an arrangement of sheet-holding systems at storage drums in turning devices of sheet-fed printing machines. 
     Turning devices, which operate according to the three-drum turning principle, consist of three sheet-guiding cylinders, the diameter of the center one of which is twice as large. 
     Such a turning device enables sheets to be turned according to the rear edge principle of turning sheets and, with that, the sheets to be printed either recto or recto and verso in one pass. 
     The storage drum has two sheet-holding systems for the front region and two sheet-holding systems for the rear region of the sheet, which are diametrically opposite to one another. The sheet-holding systems can be adjusted relative to one another in the circumferential direction, so that sheets of different length can be processed. 
     From the publication DE 39 11 630 C2, an arrangement of sheet-holding systems at a storage drum is known. The sheet-holding system for the front region of the sheet, which is constructed as a clamping gripper, is disposed permanently at the body of the storage drum. The sheet holding system, which is constructed as a suction system, is provided at a supporting element, which is detachably disposed at the body of the storage drum. 
     The supporting element and, with that, the suction device provided at the supporting element, can be adjusted in the circumferential direction by means of an adjusting shaft, which is mounted in the drum leg. A motor for actuating the adjusting shaft is disposed over a gear wheel step at one end of the adjusting shaft (on the outside) and a pinion is disposed at the other. The pinion engages a toothed segment, which is connected with the supporting element. The adjusting shaft is mounted eccentrically in the drum shaft. 
     If it is necessary to adjust the sheet-holding systems relative to one another in the circumferential direction of the storage drum, the adjusting shaft, which acts over the pinion and the toothed segment on the supporting element, is rotated by means of the motor and the gear wheel step. The suction device is shifted with the supporting element relative to the clamping gripper. 
     The large expenditure for parts is a disadvantage of such an adjusting device of the sheet-holding systems. Many gearing elements engage one another with clearance, so that the adjustment of the sheet-holding systems with respect to the dimensions of the sheet, which is to the processed, is inaccurate. The drilling and milling in the drum shaft lead to a weakness in the drum leg. 
     The DE 39 008 18 C1 shows a sheet-guiding drum with an inner shaft and an outer drum with at least one segment, which can be adjusted in the circumferential direction with respect to the inner shaft. The sheet-holding systems are assigned to the inner shaft and the outer drum, which are coupled together by means of a multiple-plate clutch. 
     The clutch is between an end surface of the segments and a journal pin of the shaft. The clutch can be actuated over a tie rod, which can be actuated from the outside, and a clamping lever and, with that, the connection between the shaft and the segment can be undone. After that, both can be adjusted relative to one another with the sheet-holding systems. 
     The large expenditure for parts is a disadvantage of this fixing and loosening device. Access to the clutch within the bearing of the sheet-guiding cylinder for maintenance work in the event of wear and contamination is difficult. In this case also, the drilling and milling leads to a weakness in the leg. 
     It is an object of the invention to provide an arrangement of sheet-holding systems at storage drums, which ensures a stiff construction of the storage drum and a simple adjustment of the sheet-holding systems relative to one another. 
     Pursuant to the invention, this objective is accomplished by the distinguishing features as claimed. 
     Due to the arrangement of a central axis in the basic body of the storage drum, which is connected with the suction system by means of the side disks and over the cam and the cam bolt, the stiffness of the basic body of the storage drum is not reduced, since the elongated holes are disposed on the operator side of the printing machine in the storage drum, while the adjustability of the sheet-holding systems by simple means is ensured. 
     This mounting and arrangement of gripper system and suction system at the storage drum enables the clutch for the systems to be disposed outside of the storage drum. With that, as a result of the good accessibility, the clutch can be manipulated easily. 
    
    
     The invention is described in greater detail in the following by means of an example and associated drawings, in which 
     FIG. 1 shows a turning device of a three-drum turning system in a diagrammatic representation in side view, 
     FIG. 2 shows a storage drum in a detailed representation as a longitudinal section and 
     FIG. 3 shows a side view, 
    
    
     FIG. 1 shows a diagrammatic representation of a turning device  1  of a three-drum turning system in a printing machine and the printing cylinders  2 ,  2 ′ with the rubber cylinder  3 ,  3 ′, which precede and follow the turning device  1 . 
     The turning device  1 , as seen in the running direction of the sheets (marked by an arrow), consists of a transfer drum  4  of single diameter, a storage drum  5  of double diameter and a turning drum  6  of single diameter. The storage drum  5  is equipped with two sheet-holding systems  8 ,  9  for the sheet  7 . 
     The sheet holding systems  8 ,  9  are constructed as a gripper system  8  for the front region and as a suction section system  9  for the rear region. The gripper system  8  and the suction system  9  can be adjusted relative to one another in the circumferential direction, so that sheets  7  of a maximum to a minimum format can be held in the front and rear regions on the storage drum  5 . The printing cylinders  2 ,  2 ′ have a double diameter. They may, of course, also have a single diameter. 
     The gripper systems  8  and the suction systems  9  are diametrically opposite to one another in the storage drum  5 . 
     The detailed construction of the storage drum  5  is shown in FIG.  2 . 
     The basic body  11  of the storage drum  5  with its tubular extension  12  is mounted rotatably in the side wall  10  of the printing machine. At the basic body  11  of the storage term  5 , the gripper system  8  is assigned to the front segments  13  of the sheet. A central axis  14  is rotatably mounted in the tubular extension  12  of the basic body  11  of the storage drum  5 . Within the side disks  17 , a cam  15 , which has a cam bolt  16  at both ends, is firmly connected with the central axis  14 . Instead of the cam bolt  16 , an element with a different cross section can also be connected with the cam  15 . 
     The cam bolt  16  passes through the side disks  17  of the basic body  11  of the storage drum  5 . Curved, elongated holes  18  are provided in the side disk  17  for the passage of the cam bolt  16 . The length of the curved, elongated holes  18  corresponds to the necessary adjusting path (maximum to minimum format) of the storage drum  5 . 
     The suction crosshead  19 , which carries the suction system  9  and extends over the width of the storage drum  5 , is assigned to the cam bolt  16 . The suction crosshead is mounted on the tubular extension  12  of the basic body  11  of the storage drum  5 . The rear sheet segments  20  of the sheets are firmly connected with the suction system  9 . 
     Only one cam  15  is provided in the example. It is, however, possible to dispose a further cam  15  at the central axis  14  in the region of the other side disk  17 . 
     The clamping device at the storage drum  5 , which can be connected with or disconnected from the gripper system  8  and the suction system  9 , is not shown. 
     For recto or recto and verso printing sheets of a different length, the sheet-holding systems  8 ,  9  must be adjusted relative to one another. This is done after loosening the clamping device by rotating the central axis  14  with respect to the basic body  11  of the storage drum  5 . A separate motor can be disposed for this purpose on the central axis  14 . In this case, the gripper system  8  is braked. 
     When the main driving mechanism is used for the adjustment, the central axis  14  is braked, the clamping device, which is not shown, is loosened and the basic body  11  of the storage drum  5 , which is connected with the main driving mechanism, and, with that, the gripper system  8  are adjusted relative to the suction system  9 . 
     After that, the sheet-holding systems  8 ,  9  once again are firmly connected with one another. The invention was described by means of a storage drum  5  in a turning device  1 . It can, however, also be used at sheet-guiding cylinders in recto printing machines for guiding the sheets in the rear region.