US 5,295,678 A · Control drive for a stack lift drive in sheet processing machines, more particularly sheet printing machines

Abstract

A system and method for controlling the lifting of a stack of sheets to be printed in order to keep the currently uppermost sheet of the stack within a certain predetermined height range for reliable removal to a feed table. A motor is operated in either a discontinuous mode or in a continuous mode to lift the sheets, the mode of operation being chosen in dependence on the speed of the press and the thickness of the sheets when compared against an established curve. A sensor is utilized to determine the vertical position of the uppermost sheet in the stack. In the continuous mode the motor speed is adjusted in accordance with the height of the uppermost sheet in the stack, while in the discontinuous mode, the motor is energized and de-energized such that the height of the currently uppermost sheet in the stack is maintained within a predetermined height range.

Claims11

Dependent claims

A system for controlling a drive means to drive a motor to lift a stack of at least one sheet of a predetermined thickness for feeding to a sheet processing machine, the system comprising:

stack height sensor means for determining the vertical position of the sheet and providing a signal representative thereof;
means for obtaining a value representative of the processing speed S.sub.1 of the machine;
means for obtaining a value representative of the thickness T.sub.1 of the sheet;
memory means for storing the values representative of the speed of the processing machine S.sub.1 and the sheet thickness T.sub.1 ;
and
control means in communication with the memory means and responsive to the signal from the stack height sensor means for operating the drive means to drive the motor until the sheet is raised to a predetermined vertical position, the control means operating the motor in either the continuous mode or the discontinuous mode in dependence only on the values of the sheet processing speed S.sub.1 and the thickness T.sub.1 of the sheet.

3 more elements

Dependencies are inferred from the claim text.

Control drive for a stack lift drive in sheet processing machines, more particularly sheet printing machines

Life of this patent

Control drive for a stack lift drive in sheet processing machines, more particularly sheet printing machines

Life of this patent

Abstract

Claims11