Systems and methods for providing rapid and safe opening of pressure nip rolls

Abstract

An actuator system for maintaining high nip forces at a roller nip is disclosed. The actuator system includes a primary actuator for urging a roller into an engaged position at which the roller contributes to providing the high nip forces at the roller nip, the primary actuator being provided attached to a movable mounting structure, and a secondary actuator for maintaining the mounting structure in a locked position, and for releasing the mounting structure, and therefore the primary actuator, from the locked position in the event of a power loss to the secondary actuator.

What is claimed is: 
     
         1 . An actuator system for maintaining high nip forces at, a roller nip, said actuator system comprising:
 a primary actuator for urging a roller into an engaged position at which the roller contributes to providing the high nip forces at the roller nip, said primary actuator being provided attached to a movable mounting structure; and   a secondary actuator for maintaining the mounting structure in a locked position, and for releasing the mounting structure, and therefore the primary actuator, from the locked position in the event of a power loss to the secondary actuator.   
     
     
         2 . The actuator system as claimed in  claim 1 , wherein the movable mounting structure provides a base for the primary actuator, and wherein the secondary actuator is coupled to the base of the primary actuator. 
     
     
         3 . The actuator system as claimed in  claim 1 , wherein the primary actuator includes a high force mechanical actuator. 
     
     
         4 . The actuator system as claimed in  claim 1 , wherein the secondary actuator includes a pneumatic cylinder. 
     
     
         5 . The actuator system as claimed in  claim 1 , wherein the secondary actuator includes a linkage system that locks when the secondary actuator is in the locked position. 
     
     
         6 . The actuator system as claimed in  claim 1 , wherein the actuator system includes at least one further primary actuator, attached to the movable mounting structure, for urging the roller into the engaged. 
     
     
         7 . The actuator system as claimed in  claim 1 , wherein the actuator system includes at least one further secondary actuator for maintaining the mounting structure in the locked position, and for releasing the mounting structure, and therefore the primary actuator, from the locked position in the event of power loss to the secondary actuator. 
     
     
         8 . An actuator system for maintaining high nip forces at a roller nip, said actuator system comprising:
 a primary actuator system for urging a roller into an engaged position at which the roller contributes to providing the high nip forces at the roller nip, said primary actuator system including at least one primary actuator that is provided attached to a base; and   a secondary actuator system for maintaining the base in a locked position, and for releasing the mounting structure, and therefore the primary actuator system, from the locked position in the event of a power loss to the secondary actuator system.   
     
     
         9 . The actuator system as claimed in  claim 8 , wherein the primary actuator system includes at least two high force mechanical actuators. 
     
     
         10 . The actuator system as claimed in  claim 8 , wherein the secondary actuator system includes at least two pneumatic cylinders. 
     
     
         11 . The actuator system as claimed in  claim 8 , wherein the secondary actuator system includes at least two linkage systems that lock when the secondary actuator system is in the locked position. 
     
     
         12 . The actuator system as claimed in  claim 8 , wherein the primary actuator system includes two primary actuators. 
     
     
         13 . The actuator system as claimed in  claim 8 , wherein the secondary actuator system includes two secondary actuators. 
     
     
         14 . A method of maintaining high nip forces, at a roller nip, said method comprising the steps of:
 urging a roller into an engaged position at which the roller contributes to providing the high nip forces at the roller nip; and   releasing a mounting structure to thereby release the roller from the roller nip in the event of a power loss to the secondary actuator.   
     
     
         15 . The method as claimed in  claim 14 , wherein the method further includes, the step of locking the mounting structure in a locked position. 
     
     
         16 . The method as claimed in  claim 14 , wherein the step of releasing the mounting structure is responsive to power loss to one or more pneumatic cylinders.