| 摘要 |
Apparatus for opening up folded sheets has a rotary withdrawing conveyor which extracts successive folded sheets from a stack and places successive withdrawn sheets into a path between two rotary spreading elements in such a way that the front edges of the sheet in the path are adjacent to the respective spreading elements and the back of the sheet is located at a level above the front edges. The spreading elements are driven in opposite directions and carry jaws which engage the respective front edges of a sheet therebetween in first angular positions of the spreading elements, whereupon the jaws move the sheet downwardly to move its front edges apart and to separate it from the withdrawing conveyor, and ultimately release the sheet in second angular positions of the spreading elements so that the sheet can descend onto a removing conveyor. The spreading elements are rotated by a crank drive which causes each spreading element to be accelerated during one half and to be decelerated during the other half of each of its revolutions. The spreading elements are in the process of being accelerated when they assume their first angular positions, and the spreading elements are in the process of being decelerated, or their peripheral speeds are relatively low, when they assume their second angular positions.
|
