Web printing presses use flexible, rubberlike printing mats wrapped completely around 4-ft-long rollers.
Web printing presses use a clamp running the entire length of a roller to secure print media. But when the roller spins at 300 rpm or faster and the clamp is too heavy, it creates centrifugal forces that strain the journal bearings, causing the roller to wobble and degrade print quality. Engineers at Agfa Corporation(www.agfa.com) redesigned the clamp (US patent 6,705,226) using inflatable bladders manufactured by Pawling Corporation's Engineered Products Division (www.pawling.com) to save time, money, and with no mechanical or electrical linkages, to reduce maintenance as well.
The new system uses a bladder nestled under a spring-steel clamp. Both run the width of the roller. When the bladder is depressurized, the spring exerts uniform clamping forces along the entire roller. Air sent through a rotary pressure collar on the roller shaft inflates the bladder to 40 psi and it lifts to release the clamp. Pawling's fabric reinforced EPDM bladder is rated at 100,000 cycles, or about 50 years of service, much longer than the presses rated life. The bladder is only secured at the ends. Friction with the clamp keeps it in place along the length of the roller.