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Winding a Uniform Roll on a Two-Drum Rewinder


PURPOSE

Compute the roll un-weighting curve for a 2-Drum Rewinder to rewind tissue parent rolls to produce rewound rolls with a uniform bulk, and with minimal loss of bulk.

AREA OF APPLICATION

  • For reels equipped with PLC based nip control, compute and apply improved loading curves.
  • For older rewinders, design and implement PLC based nip control.

METHOD OF SOLUTION

  • Analyze the current state by computing the nip pli against the winding drums and relating it to the current bulk profile.
  • Create a new nip pli curve using the above information, and past experience.
  • Convert this new pli curve to psi curve for the secondary arm loading cylinders, along with appropriate back pressure.
  • Display, if desired, the apparent bulk on the screen in real time.
COMPUTER PROGRAM

"UNWAYT" Computer Program computes the desired unwighting and the psi curves, given the rewinder geometry and loading system.

INPUT REQUIREMENT

  1. Scale drawing of the rewinder.
  2. Currently used nip control method, and loading curve.
  3. Corresponding bulk profile in the wound reel.
  4. Converting data: product variability from top to bottom, slab wastage.

MEASURE OF SUCCESS

  1. The bulk profile in the rewound rolls would be fairly flat except near the core and the outside.
  2. The bulk in the new rolls would be higher than previously rewound rolls..
  3. Slab waste would be reduced, and there would be an increased utilization of the paper.
  4. The converting machinery should pick up speed, and run steadily.

CASE HISTORIES

In light-dry-crepe (LDC) process, the target roll diameter in a Perini winders in the converting department was achieved without the need for extra sheets.

In re-crepe process, the diameter/density consistency in the small roll winding operation significantly improved the wrapping operation.

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