Methods and apparatuses for making lithographic plates

Abstract

The present invention provides methods and apparatuses for forming a mounting flange on a printing plate comprising first and second portions having an arcuate portion therebetween and defining a mounting flange angle. A bending device comprising a forming surface having a radius that is less than a desired radius for the arcuate portion can be used to form the arcuate portion in accordance with the present invention. This can be done by forming the arcuate portion to have a plurality of spaced apart bends that cooperatively define the arcuate portion.

1 . A method of forming a mounting flange on a printing plate, the mounting flange comprising first and second portions having an arcuate portion therebetween and defining a mounting flange angle, the method comprising the steps of: 
 defining a desired radius for the arcuate portion of the mounting flange of the printing plate;    providing a bending device comprising a forming surface having a radius selected to be less than the desired radius for the arcuate portion of the mounting flange; and    forming a plurality of spaced bends in the printing plate with the bending device, each of the spaced bends defined by the radius of the forming surface of the bending device wherein the plurality of spaced bends cooperatively define the desired bend radius for the arcuate portion of the mounting flange.    
     
     
         2 . The method of  claim 1 , wherein the desired radius for the arcuate portion of the mounting flange is selected based on a minimum bend radius for the material type and thickness of the printing plate.  
     
     
         3 . The method of  claim 1 , wherein the step of forming a plurality of spaced bends comprises positioning the forming surface of the bending device relative to a predetermined location of the printing plate and forming a first bend in the printing plate at the predetermined location.  
     
     
         4 . The method of  claim 3 , comprising spacing the forming surface of the bending device from the first bend and forming a second bend in the printing plate.  
     
     
         5 . The method of  claim 4 , comprising forming at least one additional bend in the printing plate by spacing the forming surface of the bending device from a previously formed bend and forming the at least one additional bend.  
     
     
         6 . The method of  claim 1 , comprising forming an image on the printing plate before forming the plurality of spaced bends in the printing plate.  
     
     
         7 . A method of forming a mounting flange on a printing plate, the mounting flange comprising first and second portions having an arcuate portion therebetween and defining a mounting flange angle, the method comprising the steps of: 
 defining a desired radius for the arcuate portion of the mounting flange of the printing plate;    providing a bending device comprising a forming surface having a radius selected to be less than the desired radius for the arcuate portion of the mounting flange; and    forming the arcuate portion of the mounting flange by: 
 positioning the forming surface of the bending device in a predetermined position relative to the printing plate;  
 forming a first bend at a predetermined location in the printing plate wherein the first bend is defined by the radius of the forming surface of the bending device; and  
 spacing the forming surface of the bending device relative to the first bend and forming at least one additional bend spaced from the first bend wherein the first bend and the at least one additional bend spaced from the first bend cooperatively define the desired bend radius for the arcuate portion of the mounting flange.  
   
     
     
         8 . The method of  claim 7 , wherein the step of spacing the forming surface of the bending device relative to the first bend comprises retracting the forming surface of the bending device relative to the first bend while the printing plate is stationary.  
     
     
         9 . The method of  claim 7 , wherein the step of spacing the forming surface of the bending device relative to the first bend comprises advancing the first bend of the printing plate relative to the forming surface of the bending device while the forming surface of the bending device is stationary.  
     
     
         10 . The method of  claim 7 , wherein the step of spacing the forming surface of the bending device relative to the first bend comprises moving both the forming surface of the bending device and the printing plate relative to each other.  
     
     
         11 . An apparatus for forming a mounting flange on a printing plate, the mounting flange comprising first and second portions having an arcuate portion therebetween and defining a mounting flange angle, the apparatus comprising: 
 a bending device, the bending device comprising: 
 a supporting bed;  
 an anvil comprising a forming surface having a predetermined radius and a mandrel positioned relative to the forming surface of the anvil, the mandrel capable of being controllably rotated about the forming surface of the anvil to bend a printing plate when positioned on the supporting surface; and  
 means for selectively varying the relative position of the forming surface of the anvil of the bending device and a predetermined portion of a printing plate when positioned on the support surface; and  
 a control system comprising programming instructions that can direct the bending device to form a plurality of spaced bends in a printing plate, each of the spaced bends defined by the radius of the anvil of the forming surface of the bending device wherein the plurality of spaced bends cooperatively define a desired radius for the arcuate portion of the mounting flange and wherein the desired radius of the arcuate portion is larger than the radius of the forming surface of the anvil of the bending device.  
   
     
     
         12 . The apparatus of  claim 11 , wherein the means for selectively varying the relative position of the forming surface of the anvil of the bending device and a predetermined portion of a printing plate comprises a motor that can move the anvil under the control of the control system.  
     
     
         13 . The apparatus of  claim 11 , wherein the means for selectively varying the relative position of the forming surface of the anvil of the bending device and a predetermined portion of a printing plate comprises a conveyor that can move the printing under the control of the control system.  
     
     
         14 . The apparatus of  claim 11 , wherein the programming instructions of the control system include an algorithm that can design the arcuate portion of the mounting flange as based on information comprising the radius of the forming surface of the anvil and a desired mounting flange angle.  
     
     
         15 . A printing plate that can be mounted on a plate cylinder of a printing press, the printing plate comprising a mounting flange comprising first and second portions having an arcuate portion therebetween and defining a mounting flange angle, the arcuate portion having a radius and comprising a plurality of spaced bends that cooperatively form the radius of the arcuate portion, each individual bend of the plurality of bends having a radius less than the radius of the arcuate portion.  
     
     
         16 . The printing plate of  claim 15 , wherein the arcuate portion of the mounting flange has a radius equal to or greater than a minimum bend radius for the material type and thickness of the printing plate.  
     
     
         17 . The printing plate of  claim 15 , wherein each of the spaced bends of the plurality of spaced bends are equally spaced from each other.  
     
     
         18 . The printing plate of  claim 15 , wherein the arcuate portion comprises a plurality of spaced bends and spaced linear portions alternating with respect to each other.  
     
     
         19 . The printing plate of  claim 15 , comprising at least one additional mounting flange.  
     
     
         20 . The printing plate of  claim 15  in combination with a printing press.