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Rewinder 15 aug 2018

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Properties of a good rewinder

Publicado en: Tecnología
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Rewinder 15 aug 2018

  1. 1. Pele Oy Rewinder Requirements August 2018
  2. 2. Pele Oy Winder and rewinder ◼ First winding happens on paper machine reel. ◼ Second winding is on the main winder for smaller rolls. ◼ Some part of the production is normally handled on the rewinder. ◼ Reasons for rewinding can be: • Rewinding defect rolls • Making splices and removing faults • Slitting narrower rolls • Changing roll diameter or core dimensions ◼ If you need a good rewinder of trim width 2500 mm please contact me: ◼ 2 Paper machine Winder Rewinder
  3. 3. Pele Oy Roll quality and rewinder ◼ Drum diameters of a two-drum winder have big effect on roll quality and winder capacity. Rewinder drums should have same diameter as the main winder. 3 Good rewinder – large diameter drums (850 mm) Common rewinder – small diameter drums (500 mm)
  4. 4. Pele Oy Effect of speed changes ◼ On a rewinder there are more accelerations and decelerations than on the main winder. These have effect on the roll structure. In practice deceleration always hardens the roll and acceleration loosens. ◼ During deceleration roll weight will be more on the front drum and the nip there can be too hard causing roll defects. 4 Picture: David Roisum
  5. 5. Pele Oy Effect of splicing on roll structure ◼ Rolls having winder splices are never as good as normal rolls. ◼ If the splice is made because of web break in the previous winding, the winder must be decelerated before the splice, which increases web tension. ◼ During the splicing the web can be loose, which decreases roll hardness. ◼ After the splice winder is accelerated, which reduces roll hardness. ◼ On top of this loose part nip effect is higher and roll hardness is increased again. ◼ When drum diameter is higher, nip effect is smaller. This is one reason that rewinder drum diameter should be high. Roll hardness Roll diameter Splice 5 Picture: Pekka Komulainen
  6. 6. Pele Oy Requirements of good rewinder ◼ Good rewinder should have the following similar properties as main winder to make same roll quality with high capacity: • Large diameter drums for good roll quality and smooth high capacity winding • Electric unwind for fast acceleration and deceleration • Automatic trim change in case of several roll widths • Accurate double spreader for efficient separation of narrow rolls ◼ If you need a good rewinder of trim width 2500 mm please contact me: 6