Calender residual barring correction during roll grinding, PaperCon 2010 Conference
Please Note: This document will be available in PDF format in the "My Electronic Documents" link on the home page once your order has been completed. Please make sure you have the latest version of Acrobat Reader. Click on the Acrobat Reader icon to check for the latest version, it’s FREE. To print a hardcopy of a PDF file correctly you must have a postscript printer. If you are not sure if your printer is a postscript printer please refer to your owner’s manual.
Barring phenomena on calender stacks cause machine direction thickness and gloss variations that affect paper quality and pressroom runnability. Calender rolls marked by excessive barring can be reground at the mill. However, many mills are not equipped to accurately measure the amplitude of residual barring corrugations after regrinding, and therefore cannot effectively remove them. A tool was developed to measure residual barring corrugations on calender roll surfaces. A very accurate linear displacement measurement sensor is the key feature of the design. The tool can be used to measure rolls on a calender stack during a machine shut-down or can be used to monitor rolls on the grinder. The tool has been used in different mills to measure and follow-up the roll surface barring amplitude during regrinding. Results show that for some mills, the standard regrinding techniques were inadequate, since the final amplitude of residual corrugations was still high after regrinding. A modified regrinding procedure was proposed and applied with success in every case. The modified regrinding techniques, in parallel with the measurements, helped the mills to reduce the level of residual barring.