摘要 |
A drive for the doctor blade of a gravure type printing press oscillates the doctor blade in a non-repeating motion. A doctor slide is coupled to the doctor blade, and oscillated on the frame by a first piston-cylinder unit. A pneumatic valve slide is driven back and forth on the frame by a second piston cylinder unit, between a first pair of end stops mounted on the doctor slide and between a second pair of end stops mounted on the frame. Upon engagement of the end stops on the doctor slide, the valve slide provides a pressure signal to reverse the direction of motion of the doctor slide. Upon engagement of the end stops on the frame, the valve slide provides a pressure signal to reverse its own direction of motion on the frame. |