Device for feeding sheets

Abstract

A device is provided for feeding sheets of a sheet stack pressing against front edge stops to a printing cylinder using transport suction devices, which engage a particular uppermost sheet in the area of the sheet rear edge and bring it in a conveyance direction, sheet transport means and sheet acceleration means downstream therefrom being provided between the front edge stops and the printing cylinder. The object of the invention is to provide a device for feeding sheets which occupies little installation space, maybe implemented using simple means, and does not disadvantageously influence the productivity of the machine which processes sheets. The object is achieved according to the invention in that the sheet acceleration means ( 43 ) are directly downstream from the front edge stops ( 7 ).

1 . A device for feeding sheets ( 2 ) of a sheet stack ( 3 ) pressing against front edge stops ( 7 ) to a printing cylinder ( 49 ) having transport suction devices ( 13 ,  14 ), which engage a particular uppermost sheet ( 2 ) in the area of the sheet rear edge ( 2 . 2 ) and bring it in a conveyance direction ( 18 ), sheet acceleration means ( 43 ) being provided between the front edge stops ( 7 ) and the printing cylinder ( 49 ), characterized in that the sheets ( 2 ) may be fed to the sheet acceleration means ( 43 ) by the transport suction devices ( 13 ,  14 ). 
     
     
         2 . The device according to  claim 1 , characterized in that a pre-gripper ( 44 ) or a pre-gripper drum are provided as the sheet acceleration means ( 43 ). 
     
     
         3 . The device according to  claim 2 , characterized in that laying marks ( 48 ) are associated with the pre-gripper ( 44 ) or the pre-gripper drum. 
     
     
         4 . The device according to  claim 1 , characterized in that a sheet routing device ( 40 ), which guides free sheet front edges ( 2 . 1 ) during the transport of the sheets ( 2 ), is provided at least between the front edge stops ( 7 ) and the sheet acceleration means ( 43 ). 
     
     
         5 . The device according to  claim 4 , characterized in that the sheet routing device ( 40 ) comprises upper sheet routing means ( 41 ) and lower sheet routing means ( 42 ). 
     
     
         6 . The device according to  claim 5 , characterized in that the upper sheet routing means ( 41 ) are implemented opposite to a conveyance direction ( 18 ) of the sheets ( 2 ), extending beyond the front edge stops ( 7 ). 
     
     
         7 . The device according to  claim 5 , characterized in that the lower sheet routing means ( 42 ) are operationally linked to a sheet flap ( 8 ), which forms an extension of the stop faces ( 7 . 1 ). 
     
     
         8 . The device according to  claim 1 , characterized in that first transport suction devices ( 13 ) and second transport suction devices ( 14 ) are provided and drives controllable independently from one another are associated therewith. 
     
     
         9 . The device according to  claim 8 , characterized in that the transport suction devices ( 13 ,  14 ) guide the sheets ( 2 ) during transport in the conveyance direction ( 18 ) in a sheet conveyance plane ( 30 ) and describe a path located above the sheet conveyance plane ( 30 ) during the movement opposite to the conveyance direction ( 18 ).