Winding a Uniform Tissue and Towel Roll



A roll of paper is mathematically modelled as an ArchimedianSpiral: the growth of the roll per revolution is a constantamount equal to the wound caliper of the sheet. Any variation inthis growth rate will result in:

  • uneven wind,
  • rings of hard and soft wind,
  • wrinkles in the wind, or
  • sheet breakouts during winding.

The targets of any tissue converting operation are

  • uniformity of wind for appearance,
  • maximizing roll size while maintaining firmness, and
  • attaining high productivity.

Winding of tissue and towel rolls on a PCMC or a Perini winder is primarily a kinematic phenomenon. To create a true Spiral, the length of paper wound per unit time must equal to the length of paper passing a reference point in the machine, less the change in the path length as a result of the roll moving in space.


PM Winding 1


PCMC CENTER WINDERS

WEBCON services the following meter-winding drives:

  • Mechanical cone-pulley drives of the older 150 Series

  • Electronic drives (all generations) of the newer 200/250 Series

  • Drives designed in-house

    • A thorough mathematical analysis to design the meter windingprofile takes into consideration the following:

    • roll diameter growth,
    • turret indexing motion (velocity and displacement),
    • turret swing motion (in case of 150 Series winders),
    • epicyclic motion of mandrel pulleys on serpentine belt,
    • drive regulation.

    WEBCON's method of computing meter-winding profile:

    • Procure roll specifications:

      • core outside diameter,
      • finished roll diameter,
      • sheet count, and
      • sheet length.

    • Procure/measure the geometry of the winding area of the winder including bedroll and the turret.
    • Trace existing mechanical cam, or copy the PLC table.
    • Compute 360 points on the winding curve as a ratio of the serpentine belt velocity to paper velocity.
    • Make dynamic corrections at the two ends of the winding curve based on sheet properties and past experience.
    • Convert the belt velocity to one of the following:

      • Cone pulley drive: design the cam profile, andcreate N-C code for milling. Machining support also available.
      • Electronic drive: create the profile table to suit the PLC program.
      • Any homemade drive: the computer program can be tailored to suit.

    • Provide set points for the winder with either drive.
    • Start-up support is available.

    Measure of success:

    Uniformity of wind from the core to the outside, as evidenced by the lack of hard and soft bands and wrinkles.

    • Fewer perforation breakouts.
    • Firmer rolls improve wrapper operation.
    • Usually an increase of winder speed.
    • Reduced waste.

    Case Histories:

    The meter winding cams generated by WEBCON have performed better than what they replaced, especially for high bulk-to-basis weight sheets and embossed products.

    The hydrostatic drive has been a highly operator friendly drive which requires little maintenance and upkeep.

    Sensitivity:

    Since our cams or cam tables are kinematically exact, they perform better with hard (slip-free) drives. Better results are attained if the winder front end is mechanically overhauled. Any slip in the serpentine belts or softness of the electronic drive is undesirable.


  • PERINI and OTHER SURFACE WINDERS

    • Our computer analysis covers the entire range of surface winding geometries: Perini, PCMC, Consani, etc. The clock in all these winders is the infeed roller, or the bedroll. The mathematical analysis takes into account the following:

    • roll growth rate,
    • contact point shift on the infeed roll and the other winding roller.

    The output of the computer program is:

    • the swing angle of the third (rider) roller,
    • the varying speed of the other winding roll, and
    • the varying speed of the rider roller.

    This output can be converted into:

    • a mechanical cam for rider roller (Diatrol for Perini),
    • electronic cam to turn the torque tube for rider, and
    • winding speed profiles for the winding rollers.

    Improved Diatrol Design:

    The Diatrol design of Model 800 type Perini winders suffers from a coupling effect of its two controls. Any adjustment of roll size must be followed by readjusting the rider position at the start of the wind. Usually 2 or 3 iterations are necessary to retune the winder to a new roll size.

    WEBCON offers a design modification of the Diatrol Linkage. This design fairly uncouples the above two adjustments; i.e., trimming of the diameter does not require a follow up adjustment.

    Copyright 2000 Webcon, Inc.