A solution for jumbo roll bouncing in the secondary arms

A mill reported that their jumbo rolls were bouncing. This started after their reel's flattened secondary arm rollers were replaced with fresh, round rollers.

Analysis

Reel bouncing is a common occurrence on brown grade machines due to caliper variations and/or parent roll variations due to turn-up / broke wrapped within the roll. The excitation starts because there is limited friction between the reel spool bearing housings (round) and the secondary arm loading rollers (round). In many cases the secondary arms are pneumatically loaded. The pneumatic loading system is "squishy" - meaning there is less stiffness to dampen the vibration than there would be with a hydraulic loading system.

Solution

By locking both secondary arm nip rollers in place, thus preventing them from rotating freely, the excitation will be reduced or eliminated completely. Locking in place can be accomplished by welding or bolting a piece of keystock to the secondary arm - then tackwelding the roller to the keystock.

If a bronze material can be substituted in place of the common steel rollers it will be even better.

Bronze roller on reel secondary arm

If you are interested in a Valmet equipment solution to remedy this problem, we supply bronze "rollers" (see photo) with the ability to rotate in 120 degree increments as the rollers wear to ensure uniform contact from the tend side to the drive side.

For more assistance with your reeling problems, contact your Valmet representative.