EXPERIMENTAL AND THEORETICAL OBSERVATIONS OF THE DYNAMICS OF PAPER INA PRINTING PRESS FOLDER

The jaw folder is widely used in the printing and paper converting ind ustry, having the purpose of placing a fold in a sheer or sheets of pa per in a direction perpendicular to their direction of motion. The dyn amics of the sheer are complex, involving the rapid reversal of motion of half of the sheet, and are not presently well understood. Through analysis of high-speed cine films of a typical jaw folder, the authors have quantified the positions and accelerations of the sheet during t he folding process. These have been verified by software simulation. T he surrounding air is shown To be of great significance to the effecti ve sheet mass and the damping of its motion. Accelerations in the plan e of the sheer are also demonstrated to be important contributors to i ts stiffness. Methods are suggested by which the design of the folder might be improved.