| 摘要 |
WEB PRINTING PRESS The invention relates to a continuous offset lithographic web printing press capable of printing a series of relatively short runs without interruption and with minimum waste of web material. The press is characterized by a plurality of individual printing units with a motor for each unit and through which units a web runs continuously. During a given run, a portion of the printing units is in a printing mode, and another portion of the printing units is in a nonprinting or thrown-off mode during which time the web moves through the unit or units thrown-off while those units are made ready for a succeeding run. Each motor of each unit is capable of driving a plurality of printing units as well as auxiliary equipment such as a web infeed and folder. A clutch is interposed between each unit and a common drive line for all the units and for the infeed and folder. When the clutch for a given unit is energized, the motor for that unit then applies driving torque to the main drive shaft for driving the auxiliary equipment. Each printing unit also includes apparatus for throwing the printing cylinder or cylinders from the web and upon throw off for changing the attitude of the web between a printing attitude, and a nonprinting or free running attitude in which contact of the web with the printing cylinders is prevented. A control system is provided and enables shut-down of and throw-off of the printing unit or units engaged in the first run at the end of a preset count and start-up of the unit or units engaged in the next run. On start up of a unit, the control system brings the printing blanket cylinder or cylinders up to speed, causes throw on of the dampener and inker, and then at the appropriate time causes blanket cylinders to be thrown-on. The control system includes mode select circuits so that any one or all of the printing units may be used for printing a given job. |
