Device for depositing sheets for a printing machine

Abstract

The invention relates to a device for depositing sheets for a printing machine, preferably for an electrophotographically operating printing machine, said device comprising at least one sheet transport member which can be driven so as to rotate and which is provided for the detection of a lead edge of a sheet and for depositing the sheet after it has covered a rotating path.

1 . A device for depositing sheets for a printing machine, the device comprising:
 at least one sheet transport member which can be driven so as to rotate and which is provided for the detection of a lead edge of a sheet and for depositing the sheet after it has covered a rotating path; and   a blower arrangement, including a radial vent and an air exit channel for the application of air to the sheet to be deposited.   
     
     
         2 . The device according to  claim 1 , wherein a current of air is directed into the curvature of the sheet guided along the path of rotation. 
     
     
         3 . The device according to  claim 2 , wherein the blower arrangement applies an air current to the sheet end that is closer to the trailing edge of the sheet. 
     
     
         4 . The device according to  claim 2 , wherein the blower arrangement includes an air exit channel for generating the air current. 
     
     
         5 . (canceled) 
     
     
         6 . The device according to  claim 2 , further including at least two coaxially rotatable cooperating sheet transport members, the first sheet transport member including a generated surface acting as a support for the sheet to be transported and determining a path of curvature for the sheet, and the second sheet transport member having at least one overlap element adapted to entrain a lead edge of the sheet, so that the lead edge of the sheet can be grasped and taken along. 
     
     
         7 . The device according to  claim 6 , wherein the first sheet transport member has substantially the shape of a disk or wheel. 
     
     
         8 . The device according to  claim 6 , wherein the second sheet transport member includes a two-arm pivot rod comprising, respectively, one overlap element in the region of its radially outward pointing free ends. 
     
     
         9 . The device according to  claim 6 , wherein the overlap element includes a tongue or tab following the path of curvature of the first sheet transport member in an approximately parallel manner. 
     
     
         10 . The device according to  claim 6 , further including two first and at least two second coaxial sheet transport member, the transport members being arranged on a joint axis in a mirror-symmetric manner so that the two second sheet transport members are located between the two first sheet transport members, so that a lead edge of the sheet can be grasped, during its travel parallel to the joint axis of the sheet transport members, by the total of four sheet transport members together. 
     
     
         11 . The device according to  claim 10 , wherein the air is substantially applied approximately in a region of a plane of symmetry of the sheet transport members. 
     
     
         12 . The device according to  claim 10 , wherein the side of the overlap elements of the second sheet transport members facing the sheet are at a radially smaller distance from the joint axis than the overlapped exterior side of the sheet applying its thickness to the radius of the generated surfaces of the first sheet transport members, so that, in its travel, the lead edge of the sheet is forced and bent slightly into the direction of the joint axis in a tension-generating manner in the region of the overlap elements. 
     
     
         13 . The device according to  claim 6 , further including a stack abutment for the lead edges of sheets, the abutment cooperating with the sheet transport members when the sheets are deposited. 
     
     
         14 . The device according to  claim 10 , wherein a plurality of each of the second sheet transport members are provided in such a manner that these multiple second sheet transport members can rotate essentially independently of each other about their joint axis and, in so doing, one of these second sheet transport members is ready to accept or grasp a subsequent sheet if another of these second sheet transport members is still busy with the transport or the depositing of a previous sheet. 
     
     
         15 . The device according to  claim 14 , further including a control element for performing on/off-switching, interruption and/or deflection for controlling the application of air. 
     
     
         16 . The device according to  claim 15 , wherein the control element is clocked. 
     
     
         17 . (canceled) 
     
     
         18 . The device according to  claim 15 , wherein the control element includes a stack height feeler. 
     
     
         19 . The device according to  claim 18 , further including a sensor arrangement for detecting the respectively reached stack height or the reached stack level, the sensor arrangement including the stack height feeler acting, at the same time, as a sheet stack depressor, the stack height feeler being mechanically controlled (guide rocker  12 ) to lift off the stack of sheets in order to clear the stack of sheets to allow depositing of the next sheet on the stack of sheets. 
     
     
         20 . The device according to  claim 19 , wherein the stack height feeler is mechanically coupled with the sheet transport members. 
     
     
         21 . The device according to  claim 20 , further including guide rockers that couple the stack height feeler with the sheet transport members. 
     
     
         22 . The device according to  claim 21 , further including a plurality of stack height feelers arranged across the stack width. 
     
     
         23 . The device according to  claim 22 , wherein three stack height feelers are provided, one of which is arranged in the middle of the stack of sheets and the other two of which are arranged at respective distances from one side and the other side of the centrally arranged stack height feeler. 
     
     
         24 . The device according to  claim 22 , wherein the central stack height feeler is the control element. 
     
     
         25 . The device according to  claim 18 , wherein the dimensions of the stack height feeler are such that it can block or screen an air exit channel. 
     
     
         26 . The device according to  claim 25 , wherein the stack height feeler includes a sheet metal tab. 
     
     
         27 . The device according to  claim 2 , further including at least one guide element blocking a grasped sheet at least in centrifugal direction and being provided between the point where the sheet is grasped and the point where the sheet is released, in order to force the radius of curvature of the sheet to be maintained. 
     
     
         28 . The device according to  claim 1 , further including at least two air outlet nozzles at different heights. 
     
     
         29 . The device according to  claim 28 , wherein the upper air outlet nozzle can be switched off earlier than the lower air outlet nozzle. 
     
     
         30 . The device according to  claim 1 , further including a guide element blocking a grasped sheet at least in centrifugal direction between a grasping location and a depositing location of the sheet in order to force the radius of curvature to be maintained by the sheet. 
     
     
         31 . The device according to  claim 30 , wherein the upper air outlet nozzle is switched off after the trailing edge of the grasped sheet has left the guide element that blocks the sheet in centrifugal direction. 
     
     
         32 . The device according to  claim 1 , further including a cascade of air outlet nozzles. 
     
     
         33 . The device according to  claim 32 , wherein the cascade includes an air line following a curved path with a plurality of air outlet nozzle openings. 
     
     
         34 . The device according to  claim 33 , wherein the air line includes a sheet transport member having the shape of a disk or a wheel or the shape of a disk segment or a wheel segment and at least partially hollow.