FINISHING/CONVERTING

Stone-Consolidated's switch to SC-A production at Fort Frances, Ont., is aided by a new reel that controls core losses and reel-induced defects

Winder-based Reel Design Facilitates Grade Changes

By GERALD J. KRAMER,

When Stone-Consolidated changed the grades produced on its No. 6 paper machine at its Ft. Frances, Ontario, mill, the company anticipated difficulties with dry-end adjustments. The new grade-a supercalendered-A (SC-A) equivalent-is more dense, smooth, and highly finished than the book- and machine-finish grades for which the machine was initially equipped. The mill was concerned that the existing equipment would not accommodate a desirable wound-roll structure with the texture of the new grade.

To help alleviate problems, the mill scheduled a rebuild to supplement the grade change, including a new stock approach system, winder, soft calender, and the first commercial installation of a new reel design. In contrast to offline calendered grades where the reel builds a bulky base sheet, the TNT reel from Beloit winds the finished product implementing the principles of good winding-torque, nip, and tension.

The new reel soon resolved the mill's concerns that the new sheet's low porosity and coefficient of friction would cause air bursts and crepe wrinkles in the paper rolls. With its ability to wind jumbo paper rolls on a paper machine producing a demanding grade, the new reel concept has exceeded mill expectations.

NEW REEL DESIGN. Designed to build jumbo parent rolls 92 in. (2.33 m) in diameter, Stone-Consolidated's new reel is 178 in. (4.5 m) wide. In addition, the reel's design borrows methods from winder design, also taking advantage of the three major tools of winding-torque, nip, and tension. It does not use primary or secondary arms, and it eliminates all transfers of torque, nip, and tension control. The following are four significant innovations that make this reel different from conventional ones:

• Constant spool elevation
  
• Load-controlled moving drum
  
• Continuous centerwind
  
• Position-controlled spools.
  

From the time the spool enters the reel until it is stopped at the braking station, the new reel design keeps the spool built by the paper roll on a level rail. There are no changes of spool elevation as experienced on conventional reels with primary arms and automatic spool loaders. Drum and spool support throughout the roll-building process minimizes wound-in roll defects. Also, spool deflection is overcome by using large diameter spools. In addition, load cells mounted under the reel drum monitor the nip load applied to the paper, providing accurate measurement and closed-loop feedback.

Experience has shown that torque is the most effective roll structure tool for the production of a wide variety of grades. The new reel applies continuous and uninterrupted torque to the winding paper roll from the first wrap to the last. It has two centerwind drives-the drive on the front winds the first spool and the drive on the back winds the second spool. Since the drives alternate on spools, there are no transfers of drive control.

A tension roll ahead of the drum, which has proven effective, controls tension. In addition to providing closed-loop control, it offers a way to monitor the sheet tension. Since paper is an elastic material, the more it is pulled at high tensions, the less flexible it is for converting and finishing operations and the more likely sheet breaks are to occur. Thus, building a paper roll at the lowest tensions possible while maintaining good runnability for the converter is important.

Operators have complete control of torque, nip, and tension, and are able to set point curves and monitor the actual winding process through direct feedback. The new reel may be operated in draw, tension, or motor current modes of operation. Completely automated, turn-ups may be programmed for roll diameter or total reel length.

STONE-CONSOLIDATED'S REEL. Because it offered solutions to the problems inherent with conventional reel technology, the simplicity of the Beloit reel design interested the Stone-Consolidated's project team. The decision was made to install this reel on the No. 6 paper machine to operate with the soft calenders, giving the paper machine the ability to produce the new SC-A equivalent grade online. The quality of the jumbo rolls, also a major factor of the rebuild, would be reflected in the successful runnability of the sheet in converting and finishing operations.

The No. 6 paper machine is an older, existing machine in a vintage machine room. At first, there was concern about the reel fitting in the space allotted, including overhead clearance of the machine room crane. However, the design of the new reel permitted changes to be made to its original configuration, and the installation of the unit in the compact physical constraints of the machine room was successful. These design changes improved the operation of the reel and provided access to maintain it.

The new reel was completely erected at Beloit's factory, along with all of the drive components, controls, and hydraulic systems. The reel was test run for several weeks using jumbo rolls supplied by the mill. These trials gave Beloit's engineering team an opportunity to prove the unit's operation in the new configuration that was designed to fit in the mill's machine room. Setup and operation of the new reel at the factory also gave mill operations and maintenance personnel the chance to become familiar with the unit and to receive hands-on training.

REEL PERFORMANCE. To justify the installation of a new reel, Stone-Consolidated had specified that total waste due to core losses, slabbing at turn-up, and any reel-induced defects should be 0.5% or less. Since the new reel does not use primary or secondary arms, the typical problem of primary-to-secondary-arm transfers of torque and nip were solved by the reel's design.

Performance of the reel since startup has been excellent. Presently, the waste rate is 0.45%, with less than 0.25 in. (6 mm) at the core. Crepe wrinkles above the core and air bursts-two major concerns with the new dense, non-porous SC-A grade on the No. 6 paper machine-have not been experienced.

In addition, both winder and press room feedback give no indications that any reel-induced defects are occurring. This includes shipping rolls of 50 in. (1.27 m) in diameter. Also, the air-assisted goose neck turn-up works well, and successful turn-up rates of 99% have been achieved.

GERALD J. KRAMER is product line manager for reels at Beloit Corp., Beloit, Wis.