Printing unit and register mechanism for mounting a printing sleeve

An offset printing unit including an automatic register system, comprising:

• a housing including a first and a second housing section,
• a central impression cylinder including a first journal and a second journal, the first journal rotatably supported in the first housing section and the second journal rotatably supported in the second housing section, a web at least partially wound around the central impression cylinder;
• at least two blanket cylinders in rolling engagement with the central impression cylinder, each blanket cylinder having a first end and a second end, each blanket cylinder including a third journal at the first end, the third journal of each blanket cylinder being rotatably supported in the first housing section, the second end of each blanket cylinder being unsupported when the printing unit is not in operation;
• and
• at least two print cylinders, each print cylinder disposed in rolling engagement with a respective one of the at least two blanket cylinders, each print cylinder having a sleeve-shaped print form mounted thereon, a first target located on an outer surface of each print form, a second target located on an outer surface of each print cylinder, a plurality of apertures located on the outer surface of each print cylinder;
• a sleeve expansion mechanism coupled to each print cylinder, the sleeve expansion mechanism transmitting compressed air through the plurality of apertures to radially expand each print form;
• at least two motors each having a wheel mounted thereon, each wheel contacting a respective print form when the print form is in its expanded state;
• a first sensor mounted adjacent to each print cylinder for detecting the first target;
• a second sensor mounted adjacent to each print cylinder for detecting the second target;
• a control unit having inputs connected to the first sensors and the second sensors, and having outputs connected to the motors, the control unit controlling the circumferential position of the print forms relative to the print cylinders as a function of the signals received from the first and second sensors.

A printing unit including an automatic register system, comprising:

• a print cylinder having at least two sleeve-shaped print forms mounted thereon, a first target located on an outer surface of each print form, a second target located on an outer surface of a print cylinder, a plurality of apertures located on the outer surface of the print cylinder;
• a sleeve expansion mechanism coupled to the print cylinder, the sleeve expansion mechanism transmitting compressed air through the plurality of apertures to radially expand the print forms;
• at least two wheels, each wheel contacting a corresponding print form when the corresponding print form is in its expanded state, the at least two wheels driven by at least one motor;
• at least two first sensors mounted adjacent to the print cylinder for detecting corresponding first targets;
• a second sensor mounted adjacent to the print cylinder for detecting the second target;
• a control unit having a first input connected to the first sensors, a second input connected to the second sensor, and an output connected to the at least one motor, the control unit controlling the circumferential position of the print forms relative to the print cylinder as a function of the signals received from the first and second sensors.