Sheet stacking apparatus

摘要

A downstacker for paperboard sheets includes a sheet speed reducing shingler positioned in the stacking station and forming a shingling nip with the top sheet of the continuously descending stack. The shingling nip is positioned to engage and nip the next following sheet simultaneously with engagement of the stacking station backstop by the preceding sheet, thereby obviating sheet marking by an overrunning nip roll. A false backstop is periodically interposed to define a stack separation level and create an offset in the stack which engages the end of a separating fork as the continuously forming stack descends to facilitate insertion of the fork supporting into the stack. The fork provides interim support for the upper stack portion which continues to form while the lower stack portion is rapidly discharged.