Paper Machine Couch Roll
Paper machine couch roll is for dehydrating the paper sheet to increase moisture uniformity of the sheet, there are different types couch roll of paper machine for different needs.
Paper Machine Couch Roll Types
Upper Couch Roll: The lightweight roll with large diameter, which located above the vacuum couch, operates at low pressure to smoothen the paper sheet and further enhance the dewatering effect before leaving the felt. The upper couch roller is coated the material with a very soft (160 to 250 P&J hardness) and high release paper that can resists steam and chemical attacking.
Mesh Couch Roll: The cylinder couch roll operate relative to the sheet forming cylinder mould, form a nip to dewater the sheet passing through the cylinder mould and deliver the sheet to the felt bottom, and the sheet is delivered to press section by felt. The coating material for mesh couch roll is usually a soft rubber or polyurethane material (200 to 250 P&J) with anti-aging and heat-resistant properties. Coatings applied to cylinder mnould paper machines also is required excellent chemical resistance.
Cylinder Mould Vacuum Press Roller: In cylinder mould paper machine, the cylinder mould vacuum press roll operate relative to the vacuum cylinder mould, forming a nip in front of the press section for dewatering. These rollers are coated high wear-resistant rubber or polyurethane material (hardness 70 to 125 P&J) with 25 to 30 mm thick and drilled on the coating surface for optimal venting and dewatering.
Dehydration Couch Roll: In cylinder mould paper machine, the dewatered couch roll operates relative to the dewatering cylinder mould, which located behind the last forming cylinder, creat a low pressure nip for dewatering before the sheet is delivered to the vacuum cylinder or first press. Cladding materials is highly abrasion resistant rubber or polyurethane with medium softness (90 to 150 P&J), good toughness, chemical resistance and relatively long service life cycle.
