METHOD AND APPARATUS FOR CONTROLLING CONVERTING REWINDER LINES

In a production operation for producing rolls of tissue or towel from a pare nt roll including a converting line provided with a rewinder, an accumulator an d downstream processing equipment, a method of controlling the converting line includes: (a) providing an upper target limit for the inventory level of the accumulator; (b) providing a lower target limit for the inventory level of t he accumulator; (c) determining the slowest maximum speed of the downstream equipment; (d) determining the fastest minimum speed of the downstream equipment; (e) monitoring the average production speed of the rewinder; (f) monitoring the actual inventory level of the accumulator; (g) generating a master speed reference value which: (i) corresponds to said slowest maximum speed of the downstream equipment if the actual inventory level of said accumulator is greater than about the upper target limit for the inventory level of the accumulator; or (ii) corresponds to the fastest minimum speed of the downstream equipment if the actual inventory level of t he accumulator is less than the lower target limit for the inventory level of t he accumulator; or (iii) is based on the actual production speed of the rewinde r if the actual level of inventory in the accumulator is less than about the upper target limit for the inventory level of the accumulator and greater than about the lower target limit for the inventory level of the accumulator; and (h) controlling the producti on speed of the downstream equipment based on the master speed reference value. A contro l system for implementing the method is also described.