Rotational Measurement
Measurement of rotational speed determines the rate of cylinder rotation in paper converting and finishing machinery. When a web of paper moves through a slitter rewinder, the angular velocity of the winding roll must adjust continuously as the roll diameter increases. This dynamic adjustment maintains a constant linear web speed, which prevents tension variations that could lead to web breaks or telescoping roll defects.
Web Tension
Feedback loops run on automated controls to regulate the motor output. If the angular velocity of the unwind roll does not decrease in proportion to the depletion of the roll, the web tension drops, causing the paperboard to sag and wander off course. Proper torque control depends on precise measurement of this rotational speed to manage the high inertia of heavy paperboard reels during deceleration.
Slitting Precision
Precise synchronization of the knives ensures a clean cut without releasing paperboard dust that might interfere with printing plates. At high operating speeds, the angular velocity of the slitting blades must exceed the web speed by a specific ratio, often referred to as the overspeed, to create a neat shear. When the blades run too slowly, they tear the sheet edges, causing lint accumulation that degrades subsequent offset lithography runs.
This edge damage can also cause moisture absorption during storage, leading to localized swelling and feeding jams on the cartoning line. High-speed cameras and rotary encoders monitor these blade spindles to maintain consistency across the entire width of the machine.
