Transfer Drum for Conveying a Sheet in a Machine of the Graphic Arts Industry

Abstract

A transfer drum for conveying a sheet in a machine of the graphic arts industry. The transfer drum is developed for controlling grippers without much effort and without much wear to the components of the gearing mechanism. The transfer drum includes grippers that are suited for holding an edge of the sheet and are arranged on a gripper shaft. Levers are fixed to the ends of the shafts. A cam mechanism for opening and closing the grippers has control cams that are connected to the frame and have contact surfaces, and cam followers fixed to the levers and in contact with the contact surfaces. Opposing torques act on the ends of the gripper shaft.

1 . A transfer drum for conveying a sheet in a machine of the graphic arts industry, comprising:
 a drum body rotatably mounted in a frame for rotation about a drum axis;   a gripper shaft disposed parallel to said drum axis, said gripper shaft having ends;   grippers mounted on said gripper shaft and configured for holding an edge of the sheet;   levers affixed to said ends of said gripper shaft;   a cam mechanism for opening and closing said grippers, said cam mechanism including control cams connected to the frame and having contact surfaces, and cam followers affixed to said levers and in contact with said contact surfaces; and   wherein said ends of said gripper shaft are subjected to mutually opposing torques.   
   
   
       2 . The transfer drum according to  claim 1 , wherein said control cams ( 14 ,  15 ,  22 ,  23 ) follow identical cam race designs. 
   
   
       3 . The transfer drum according to  claim 1 , wherein said gripper shaft is a torsion spring. 
   
   
       4 . The transfer drum according to  claim 1 , wherein said control cams include an inner control cam and an outer control cam. 
   
   
       5 . The transfer drum according to  claim 1 , wherein said gripper shaft is formed with two hollow sections disposed coaxially relative to one another and a torsion bar spring disposed inside said two hollow sections and connecting said shaft ends. 
   
   
       6 . The transfer drum according to  claim 1 , wherein said cam followers are cam rollers. 
   
   
       7 . The transfer drum according to  claim 1 , wherein said levers are bendable levers.