FOLDING-MACHINE FOR FOLDING SHEETS

1. A folding machine for the zigzag folding of sheets (10) (prints of drawings or the like), in particular according to a folding programme conforming to standards, with standard folds and if necessary equalizing folds, having a folding mechanism (1) in front of the entry to which conveyor rollers (11, 12) are arranged for guiding in the sheet (10) and in front of them - in the direction feed of the sheet respectively - at least one sensor (24) for detecting its rear edge (26) by touch, having a pulse generator and counter (18, 21) for measuring the length of the sheet, and having a control circuit linking the folding machanism (1), the sensor (24) and the pulse generator/counter (18, 21), which in dependence upon the sheet length measurement determines the positions of the folds in the sheet and causes the folding programme so determined to be executed by the folding mechanism (1), where a predetermined foldings scheme decides the maximum length of the portions of sheet lying between two folds as well as the fixed length of a portion (27) of coversheet adjoining the last fold but a measurement of the length of the sheet (10) decides the length of possibly necessary portions of equalizing fold in front of the portion of coversheet, characterized in that the pulse generator (18) is connected to a measuring roller (15) which in service runs along the sheet (10) without slip, and that in the direction of feed of the sheet the rear edge sensor (24) is arranged a) in front of the measuring roller (15) and b) at a distance from the entry (9) to the folding mechanism (1), which is at least equal to the length of that portion of sheet needed for the portions of fold which inclusive of equalizing folds adjoin a fullwidth portion of fold next the front edge.