Abstract: A method and apparatus for changing a printing plate on a plate cylinder in a sheet-fed offset printing machine is provided. The printing plate is first fed to the plate cylinder with its print-end edge leading the print-start edge. The print-end edge of the printing plate is then fixed in a first fixing device on the plate cylinder assigned to the print-end edge of the printing plate. The plate cylinder is then rotated in a direction opposite to the direction of rotation used during a printing operation to draw the printing plate around the outer circumference of the plate cylinder. The print-start edge of the printing plate is then fixed to a second fixing device on the plate cylinder that is assigned to the print-start edge of the printing plate and tensioned on the plate cylinder.

Abstract: A printing plate for an offset printing machine which comprises an electrically non-conductive material adapted for mounting on a plate cylinder of the printing machine and which has cuts in at least one area thereof adapted to cooperate with register pins arranged on the plate cylinder. An electrically conductive layer is arranged on the printing plate in the area of the cuts for making electrical contact with the register pins to facilitate proper mounting of the plate on the cylinder.

Abstract: A method for automatically feeding a printing plate in proper registry to a plate cylinder in a printing machine is disclosed. Pursuant to the disclosed method, a printing plate is advanced by a plate conveyor towards a clamping rail on the plate cylinder. After the leading edge is inserted into the clamping rail, the in-register condition of the leading edge of the printing plate is independently sensed at two sensing sites. If the leading edge of the printing plate is in register at only one site, the printing plate is released from the plate conveyor for a period of time to permit the printing plate to align itself. The printing plate is then held again by the plate conveyor and the advancement of the plate is resumed. This process is repeated until the independent sensors both indicate that registry has been achieved.

Abstract: A suspension system which is used to mount a plate nipping element on the frame of a printing machine is provided. The suspension system includes a setting arrangement adapted to move the nipping element between a position where it is engaged against the circumferential surface of a plate cylinder and a position where the nipping element is disengaged from the plate cylinder after first executing an idle stroke. The suspension system also includes a spring means adapted to support the weight of the nipping element on the frame of the printing machine when the nipping element is disengaged from the plate cylinder. In addition, the setting arrangement and the spring are adapted to allow the disengaged nipping roller to pivot away from the plate cylinder further biasing the spring when an object contacts the nipping element.

Abstract: A magazine for the automated changing of printing plates of a sheet-fed offset printing machine. The magazine includes a guiding apparatus which can be put into place on the plate cylinder for purposes of conveying used printing plates out of the plate cylinder and for feeding new printing plates to the cylinder. The guiding apparatus may be formed by a sheet-metal profile. Provision is made of further guiding surfaces and a holder so that the used printing plate may be locked by the holder. An operator then only need pull the plate a short distance out of the gripping region of a leading edge clamping rail. Stops are provided for a printing plate so that the new printing plate can be deposited on the stops. By virtue of putting the guiding apparatus into place, the new printing plate is shifted toward the plate cylinder and can be fed into the front clamping rail by the operator.

Abstract: A method and an apparatus for controlling an automated printing plate change process in a sheet-fed offset printing machine, in which a used printing plate is removed from the gripping portion of a clamping rail allocated to the leading edge of the plate cylinder and thereupon a new printing plate is guided into the opened gripping portion. Position sensors are used to determine, first, whether the front end of the used printing plate, and subsequently, whether the front end of the new printing plate, is in register in the leading edge clamping rail. Such information is used to control the plate change process. During the plate change process, the sensors are interrogated to determine whether the used plate has been removed from the plate cylinder, and whether the new printing plate is properly loaded.

Abstract: A device for introducing printing plates more simply into the opened gripping region of a tension rail assigned to the print start of a plate cylinder. The device includes an introduction rail extending over the format width of the plate cylinder and adapted to be moved against the outer circumference of the plate cylinder into a specific angular position in the region of the print start. When the introduction rail is so positioned, the front edge of the printing plate may be introduced directly into the gripping region of the print-start tension rail via an introduction face formed on the introduction rail. The outer circumference of the plate cylinder coacts with the introduction face of the introduction rail to define a funnel-shaped region for receiving the front edge of the printing plate just prior to the latter being inserted into the tension rail.

Abstract: A safety device has pivotally mounted rails for guarding impression cylinder nips in a sheet-fed rotary printing press. The guard rails are pivoted from a guard or safety position during maintenance to a second position away from the impression cylinder during printing to insure that the printed sheets are not smeared by the edges of the guard rails. The guard rails, however, also sense operator contact during maintenance to cause the inching drive of the press to shut off immediately. A hinged access cover or door on the press shields the impression cylinder and cooperating cylinder during printing, and is opened to perform maintenance. Opening of the access cover operates an electrical switch for shutting off the main drive of the press, and the access cover is mechanically connected to the guard rails by a resilient linkage which in turn causes pivoting of the guard rails toward their safety positions.