An apparatus for supplying sheets to a printing machine

Abstract

An apparatus for supplying sheets to a printing machine having a sliding work plane moving in outward and return runs, so as to subject one or more sheets thereon to printing, a station, in which the work plane pauses, being provided with a gripper for transferring the sheets from the apparatus to the work plane, with the work plane paused in the station. The apparatus includes a gantry bearing a loading plane positioned by a side of the pause station and made vertically mobile from a first variable-height operating position, and a second fixed operating position flanking the pause station. A receiving station of a stack of sheets is positioned by a side of the gantry opposite the work plane, the height of the head sheet of the stack defining a first operating position. A gripper, borne by the work plane, with the work plane in the operating position grips the head sheet of the stack and transfer it onto the work plane.

1 . An apparatus for supplying sheets to a printing machine, the machine comprising: a work plane sliding longitudinally, in an outward run and a return run, such as to subject one or more sheets, arranged thereon, to action of the printing means; at least a station in which the work plane pauses, provided with gripping means for transferring the sheets from the apparatus to the work plane with the work plane pausing in the station; the apparatus comprising: a gantry bearing a loading plane positioned by a side of the pause station and made vertically mobile, by motor means, from a first operating position, height-variable, to a second operating position, flanked to the pause station; a receiving station of a stack of sheets, located by a side of the gantry on an opposite side with respect to the work plane, at a height of the head sheet of the stack defining the first variable operating position; sheet gripping and transfer means, borne by the loading plane, destined, with the loading plane in the first operating position, to engage the head sheet of the stack in order to transfer the head sheet onto the loading plane. 
     
     
         2 . The apparatus of  claim 1 , wherein the loading plane is identified in the upper branch of a closed-loop conveyor borne by the gantry, the conveyor being motorisable either in step-fashion or continuously. 
     
     
         3 . The apparatus of  claim 2 , wherein the upper branch is flanked to the pause station of the printing machine. 
     
     
         4 . The apparatus of  claim 1 , wherein the motor means are commanded by detecting means of a height of the stack, and by detecting means of a height of the loading plane acting in combination with the defining means of the first and second operating positions. 
     
     
         5 . The apparatus of  claim 2 , wherein the conveyor is constituted by a series of belts mutually spaced by means of spaces, it comprises further comprising means, arranged in the spaces  60 , for disengaging the sheets from the upper branches of the belts. 
     
     
         6 . The apparatus of  claim 5 , wherein the means comprise: parallel shafts, situated at a same height, of which at least one is situated in a corresponding space, with each shaft affording a longitudinal flattening; activating means for synchronically activating in rotation the shafts such as to define for the shafts a rest position, in which there is no interference with at least an overlying sheet, and a work position for intercepting the sheet with at least the raising thereof such as to facilitate engagement thereof by the gripping means. 
     
     
         7 . The apparatus of  claim 2 , wherein the conveyor is constituted by a series of belts mutually distanced by spaces, further comprising means, arranged transversally to the upper branches of the belts, mobile from a lowered position, in which they do not intercept at least an overlying sheet involving the upper branches, to a raised position, in which they define a stop for the sheet. 
     
     
         8 . The apparatus of  claim 7 , wherein the means are comb-conformed, tines of which insert freely in the spaces. 
     
     
         9 . The apparatus of  claim 7 , further comprising, in the downstream end of the upper branches of the belts, a comb-conformed fixed abutment, tines of which are inserted in the spaces so as to define an abutment for the at least a sheet resting on the upper branches of the belts. 
     
     
         10 . The apparatus of  claim 1 , further comprising conveyor means having a longitudinal development parallel to the longitudinal development of the loading plane, which conveyor means extend from a loading station, upstream of the loading plane, to the receiving station; the conveyor means being conformed and dimensioned such as to support a plurality of stacks of sheets flanked to one another, and being activatable in a first advancing direction so as to transfer each stack of sheets from the loading station to the receiving station. 
     
     
         11 . The apparatus of  claim 10 , further comprising sensor means arranged along the extension of the conveyor means, downstream of the loading station and upstream of the receiving station, for detecting conveying of a stack of sheets to the receiving station and consequently deactivating the movement of the conveyor means. 
     
     
         12 . The apparatus of  claim 10 , wherein the conveyor means comprise a roller conveyor. 
     
     
         13 . The apparatus of  claim 10 , wherein the conveyor means comprise a first roller conveyor and a second roller conveyor arranged aligned and adjacent to one another. 
     
     
         14 . The apparatus of  claim 10 , further comprising a waiting station, arranged downstream of the receiving station; the conveyor means extending from the loading station to a waiting station, in order to convey towards the waiting station, following activation of the conveyor means in the first advancement direction, a stack of sheets which has reached the receiving station and which must remain in a waiting position before the sheets can be engaged by the gripping and transfer means, and transferred to the printing machine; the conveyor means being activatable in a second advancement direction opposite the first advancement direction, in order to newly transfer the stack of sheets from the waiting station to the receiving station.