Apparatus for stacking flat articles on-edge

An apparatus for stacking flat articles on-edge, the apparatus comprising:

• a stack holding unit configured to hold a stack of the articles on-edge, said stack holding unit having an article entry opening for receiving the articles, said article entry opening having a height that is smaller than a height of the articles to be stacked during operation;
• a helical drive assembly having spaced-apart helical screws disposed separately from said stack holding unit and configured to receive the articles therebetween in an on-edge orientation and to eject the articles towards said stack holding unit;
• a conveyor configured to support lower edges of the articles during transport to said stack holding unit;
• said helical screws and said conveyor being configured to cooperate to reposition each article from a first angular position with respect to a transport path to a different second angular position with respect to the transport path;
• and
• said helical drive assembly being configured to eject each article at a higher speed than an instantaneous conveying speed of said conveyor.