Method of controlling caliper of the fiber web of a parent roll and production line for producing fiber webs
AssigneeValmet Technologies Oy
InventorJaakko Haapanen
Life of this patent
Estimating the term…
Abstract
To minimize the cost of a fiber web due to the web, particularly a board web, being manufactured overly thick to compensate for loss of caliper in the reel-up, the web is made thicker just for the inner layers of what will become a parent roll. The caliper of the web is measured as or after it is unwound. A caliper curve of the parent roll as a function of the diameter of the parent roll is calculated as a function of the diameter of the parent roll and/or the customer roll. The fiber web is adjusted by changing running parameters of the production line: web speed i.e. production speed, headbox-flow, head-box consistency, coating weight of the coating paste or calender nip load.
Claims19
A method in a fiber web production line of minimizing changes in caliper of a fiber web produced on the fiber web production line after the fiber web is wound into a parent roll, the method comprising the steps of:
- forming a fiber web in web production line of a targeted caliper, wherein before a parent roll is started in a reel-up of the fiber web production line, a first length of the fiber web is formed with a caliper greater than the targeted caliper such that as the parent roll is begun, the first length of the fiber web is wound to form a first part of the parent roll with the fiber web of greater caliper;
- while the parent roll is being wound, adjusting the web production line to change the caliper of the fiber web, and thereby winding a second part of the parent roll with the fiber web having a second length with a caliper of the targeted caliper to form the parent roll, wherein the second length is greater than the first length;
- and
- wherein the fiber web of greater caliper is arranged on the interior of the wound parent roll so as to compensate for reduction of web caliper in the parent roll as wound.
A method in a fiber web production line of minimizing changes in caliper of a fiber web produced on the fiber web production line after the fiber web is wound into a parent roll, the method comprising the steps of:
- forming a fiber web in the fiber web production line and reeling the fiber web on to a first parent roll in a reel-up of the fiber web production line, such that a first length of the fiber web is formed with a caliper greater than a target caliper such that as the parent roll is begun, the first length of the fiber web is wound to form an inner part of the parent roll;
- while the parent roll is being wound, adjusting the web production line to decrease the caliper of the fiber web to the target caliper, and winding a second part of the parent roll with the fiber web having a second length with the target caliper to form the parent roll, wherein the second length is greater than the first length and is disposed exterior to the inner part of the parent roll.
Dependencies are inferred from the claim text.