| 摘要 |
A sheet of paper is folded by forming a portion of the sheet into S-shape with a folding loop of U-shape and a blind loop of opposite curvature, and pressing the opposite sides of the folding loop together in the direction from the open end towards the closed end of the loop, to produce a fold, while the shape of the blind loop is maintained without the sheet becoming folded in the region of this loop. Apparatus for performing the method is arranged to produce oppositely directed folds alternately along the length of the sheet. The opposite sides of the folding loop are pressed together by a folding roller which may cooperate with a table to both form the "S" loop and produce the fold, or a second roller which serves to clamp the sheet. In the latter arrangement a sheet deflector forms the folding loop between the two rollers when they are spaced apart, and in the former arrangement the folding roller is movable against the table, first in one direction to form the S loop and then in the opposite direction to press the folding loop against the table.
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