Press roll
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Press roll

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Generates high pressure to squeeze water out of wet paper web and compact pulp fibers.

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The press roll is a core component of the press section in a paper machine, and its working principle centers on mechanical compression dewatering and fiber compaction, serving as a critical transition between the forming and drying sections.
The specific working process is as follows:

  1. Material Infeed

    After forming in the forming section, the wet paper web (with a dryness of approximately 18%–25%) is transported to the press section by the press felt. It then enters the nip zone formed by the press roll and its mating component (such as a bottom press roll, press shoe, or couch roll).

  2. Pressure Application & Dewatering

    Driven by the machine’s transmission system, the press roll rotates synchronously with the mating component, generating high linear pressure (typically 0.3–1.5 MPa) in the nip zone. This pressure squeezes the wet paper web, forcing the free water and part of the capillary water in the pulp fiber structure out of the paper web.

    • For press rolls with blind-hole or grooved surfaces, the squeezed water is quickly collected in the holes or grooves, then discharged through dedicated water collection channels to prevent reabsorption into the paper web.
    • For rubber-covered or polyurethane-covered press rolls, the elastic surface ensures uniform pressure distribution across the paper web’s width, avoiding localized over-pressing or under-pressing.

  3. Fiber Compaction & Web Transfer

    While dewatering, the pressure compacts the loose pulp fibers, enhancing the inter-fiber bonding force. This not only improves the wet strength of the paper web to prevent breakage during subsequent transportation but also lays the foundation for the physical strength (tensile strength, tear resistance) of the finished paper.

    After passing through the nip zone, the dryness of the wet paper web is increased to 30%–40%, and it is then transferred by the press felt to the drying section for further water removal.

  4. Key Operational Requirement

    The rotational speed of the press roll must be strictly synchronized with other rolls in the press section. Any speed mismatch will cause tension fluctuations in the wet paper web, leading to web breakage or surface defects.

  1. admin –

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  2. admin –

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