Patent ID: 6776096
Filing Date: 2004-08-17
Classification: B41F,B41P

Abstract:
A method of attaching a flexible printing plate on a plate cylinder comprising:providing a flexible printing plate having a concavo-convex structure on a rear surface thereof and three or more notches at a plate front edge thereof; providing an apparatus for attaching a flexible printing plate comprising: a plate front end positioning mechanism comprising: a plate front end clamping mechanism having upper teeth and lower teeth for fixing a plate front end of said printing plate to said plate cylinder; and at least three registration pins respectively provided in said plate front end clamping mechanism in such a manner that they are respectively opposed to said notches of said printing plate; a printing plate pressing mechanism for pressing said printing plate toward said plate cylinder; a plate rear end fixing mechanism for fixing a plate rear end of said printing plate to said plate cylinder; and a packing sheet having a concavo-convex structure at least on one surface thereof and being wound and fixed around said plate cylinder in such a manner that the surface having the concavo-convex structure is faced toward said printing plate; positioning and fixing said plate front end to said plate cylinder by inserting said plate front end of said printing plate between said upper and lower teeth of said plate front end clamping mechanism to contact an inner peripheral surface of said notches of said plate front end with said at least three registration pins; winding said printing plate on said plate cylinder by rotating said plate cylinder with said plate rear end kept free, while said printing plate pressing mechanism presses said printing plate toward the entire outer peripheral surface of said plate cylinder including a ridge portion thereof using a pressure member; and pressing and fixing said plate rear end of said printing plate using said plate rear end fixing mechanism after the completion of said winding; whereby elongation of said flexible printing plate in its maximum printing length in the rotational direction of said plate cylinder during said printing plate attaching operation is controlled to be not more than 100 &mgr;m; wherein a concavo-convex structure of the rear surface of said printing plate has Ra value of less than 1.5 &mgr;m (Ra: centerline average roughness).