Device for stacking sheet-like articles such as letters

Abstract

The invention relates to a device for stacking flat articles, such as postal items. First guide (9), which form part of a stacker head (7) and which bound a stack of articles (2) already stacked in a stacker bed (1) in a plane of stacking (D), carry out an imposed to-and-fro pulse movement between a rest position (A) and an outermost position (C) transversely to a supply line (3) and in line and level with the stack to make stack space for a short time for an article (2.2) to be stacked, which article is entering at that moment via the supply line (3). The pulse movement can be realized by hanging the first guide (9) on the one hand by way of a first set of parallel leaf springs (17, 18) to a frame part (19, 20, 31, 32) in such a way that they can swing, and on the other hand by coupling them to the driving end (28) of drive (25, 26) carried on bearings in the frame part. In the rest position (A) the stack pressure exerted in the plane of stacking (D) on the first guide (9) of the stacker head (7) will (practically) completely be exerted as a sideways pushing force on the frame part. This fact can be utilized with advantage for a very accurate stack-force measurement. For that purpose the frame part is connected, on the one hand, via a second set of parallel leaf springs (33, 34) to the fixed world (35, 36, 4) and, on the other hand, via a coupling bar (37) to a force transducer (38, 39). A very small sideways displacement of the frame part under the sideways pushing force caused by the stack pressure is registered by the force transducer (39) and converted into a signal which can be used for a change of position, if any, of a stack support (8) for regulating the stack pressure.