Abstract:
Multicolor prints should be economically producible in a printing machine suited for automation. For this purpose a printing machine is configured which operates according to the collect-run principle. The multicolor prints are collected on a rubber cylinder (21 on a printing cylinder (5). The printing machine is capable of processing two printing colors (inks) in one printing unit. For the execution of the collecting printing the sheets are fed in a cycle offset to the rotation of the collecting cylinder. There are yielded very compact and simply structured printing machine configurations.
Abstract:
Multicolor prints should be economically producible in a printing machine suited for automation. For this purpose a printing machine is configured which operates according to the collecting (collect-run) principle. The multicolor prints are collected either on a rubber cylinder (21) or on a printing cylinder (5). The printing machine is capable of processing two printing colors in a printing unit (11, 12). For the execution of the collecting printing, the sheets are fed in a cycle offset to the rotation of the collecting cylinder. For the printing of both sides double-sized sheet-conducting drums (6, 13, 14) are provided, or cylinders with a turning device or alternately set-on printing units.
Abstract:
A method and device for washing the printing cylinder of a printing machine, especially an offset rotary printing machine, in which a washing device with a washing roller with a covering capable of absorbing liquid is premoistened prior to performing the first washing operation after a long standstill period of the printing machine. As a result, the efficacy of the first washing operation after an interruption to operation of the printing machine is improved, the wear on the covering of the washing roller is reduced, and damage to the printing cylinder from a dry covering of the washing roller is avoided.
Abstract:
An apparatus for clamping a flexible printing plate onto a plate cylinder including an adjustable front clamping strip for releasably engaging a leading end of the printing plate and a plurality of axially spaced pins which engage respective axially spaced holes in the rear of the printing plate. The printing plate is held on the circumference of the printing cylinder with relative little force so that any inaccuracies can be easily corrected through adjustment of the front clamping strip.
Abstract:
The accurately positioned tensioning of a printing plate on the printing cylinder of a printing mechanism. The circumference of the printing cylinder has a groove extending in the axial direction of the cylinder which accommodates a tensioning and fastening mechanism for the printing plate. The mechanism includes a front tensioning bar for the start of printing of the printing plate and a rear tensioning bar for the end of printing of the printing plate, the rear tensioning bar being disposed ahead of the front tensioning bar in the direction of rotation of the printing cylinder. Releasable fastening of the ends of the printing plate to the two tensioning bars, displacement of the rear tensioning bar in the circumferential direction of the printing cylinder over a longer tensioning path for the purpose of tensioning the printing plate over the circumference of the cylinder, and displacement of the front tensioning bar in the circumferential direction of the printing cylinder over a smaller adjustment path for adjusting the image to be printed are provided for. Adjustment of the printing plate is further facilitated by a stop fixed to the cylinder as the zero position disposed at the side of the front tensioning bar and oriented toward the rear tensioning bar. A spring urges the front tensioning bar against the stop.
Abstract:
A suction roll sheet transfer device disposed between a sheet feed table and the front lays of a sheet fed rotary printing press including a first set of suction rolls adapted for oscillating movement between a position substantially in the plane of said feed table for engaging successive sheets under suction pressure and transferring the sheet in register toward the front lays of the press and a raised position for engaging a preceeding sheet and separating it from the following sheet disposed therebelow, even when the sheets are in strongly adhering relation to each other during high speed printing operations. Suction pressure is communicated to the suction rolls in predetermined timed intervals, commencing upon retraction of the suction rolls substantially to the plane of the feed table. In a second embodiment, non-displaceable suction rolls are disposed immediately below the plane of the feeder plate upstream of the oscillating suction rolls for engaging successive sheets, under the influence of suction pressure, and guiding the sheets onto the oscillating suction rolls. In that embodiment, deionizers with air nozzles are disposed between the oscillating suction rolls and the non-displaceable suction rolls for directing a timed, pressurized air flow against successive sheets to facilitate separation of the partially overlapping sheets.
Abstract:
A densitometric sensing device in which a density measuring head, which is part of the device, traverses an ink test strip printed on a page which is fed to or placed on the device. The problem of misalignment between the thus-placed ink test strip and the scanning direction of the density measuring head is avoided by providing a plurality of density measuring receivers in the measuring head, mounted transverse to the direction of travel so that the ink test strip is always under some of the receivers. The measured density values of all of the receivers are passed to a comparison circuit which cooperates with a logic circuit to determine from the values of the signals themselves which should be used to produce a composite density value, which is then used as the density for the zone being scanned.
Abstract:
A series-produced sheet-fed offset rotary press having drum transfer systems in which sheet conveyance is carried out entirely through mechanical gripper transfers from a first impression cylinder to a transfer cylinder, then successively to a double-size transfer drum, then to a turning cylinder and then to a second impression cylinder and which are selectively engageable for multi-color printing on one side or alternately for perfecting printing and wherein, to change over sheet movement between these two operational modes the double-size transfer drum is selectively movable into one of two positions and is variable in its direction of rotation, the double-size transfer drum being engageable, in the first position and first direction of rotation and with the transfer cylinder disengaged, with two double-size impression cylinders for one-sided multi-color printing; while, in a second position and in the second direction of rotation, for perfecting, the double-size transfer drum can be lowered into engagement with the turning cylinder and the previously disengaged transfer cylinder can be lowered into engagement with the first double-size impression cylinder and with the double-size transfer drum; and wherein the distance between the impression cylinders is less than the diameter of the double-size transfer drum.
Abstract:
An apparatus and method for automatically checking and correcting register adjustment of a multi-color sheet-fed printing press wherein register marks are read by an ink densitometer on a remote control desk. The densitometer head is mounted on an X,Y positioning mechanism under the control of a register control computer so that the densitometer head scans cross-shaped register marks to determine both axial and peripheral register error. Preferably both right-hand and left-hand marks are used in order to pecisely determine skew or diagonal error, and the densitometer head rapidly traverses from one mark to the other mark. Preferably each register mark is made up of offset component marks of the primary colors and the positions of the marks are matched with their respective colors by the time sequence of scan path points of intersection. One color is chosen as a reference from which desired positions are calculated for the other component marks. The deviations are displayed to the operator and used as control values.
Abstract:
An inking or damping unit is provided for rotary printing machines in which a metering roller and transfer roller are in contra-rotating contact under pressure and a liquid feed with a self-regulating level is disposed above and between the rollers. Zonal liquid transfer is made by way of intermediate zone rollers arranged closely together side by side on a carrier tube and eccentrically movable thereon such that the intermediate rollers accurately transfer the liquid from the transfer roller to a following machine roller.