Cross Machine Caliper Profile Control on High Speed Coated Packaging Lines
Cross-machine caliper control demands real-time induction calender profiling to maintain stiffness and prevent high-speed converting line jams.
Variable Crown Roll
Profile Correction
A specialized calender roll adjusts its internal support forces to maintain a uniform pressure distribution across a moving paper web. By implementing a variable crown roll, the deflection of the roll shell is compensated for by internal hydraulic elements that press against the rotating shell from the inside. This system allows the machine to maintain a flat nip profile even when the total loading force is varied during production.
The use of this roll is standard in modern calender stacks for paperboard machines.
Hydraulic Support
The roll consists of a stationary central shaft and a rotating outer shell that is supported by hydraulic pistons. These pistons are arranged in zones along the length of the shaft, allowing independent pressure control in different areas of the nip. By adjusting the hydraulic pressure in each zone, operators can correct uneven thickness profiles across the web width.
This zone control allows the calender to handle varying board grades and widths without changing rolls. The system operates continuously to compensate for external load variations.
Caliber Control
The ability to adjust the roll profile dynamically reduces thickness variations, which prevents problems during subsequent converting and printing. It also reduces wear on the calender rolls by distributing the load evenly. Precise zone control is the standard method for achieving high quality packaging board.