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Based on: Industry Standards and Best Practices

Languages: English

Sample Transcript

Suction rolls have four major components. One, a roll shell with through drilled holes. Two, one or more suction boxes or vacuum boxes. Three, a head and journal at each end. And four, a roll cover on the shell. Suction roll shells are typically constructed of bronze or stainless steel. Holes are drilled through the shell to supply vacuum to the roll's surface. The hole pattern influences the strength of the shell. The amount of noise generated and the amount of open area available. The suction press roll shell is the primary interface for applying pressure to the sheet in the nip. It is designed to handle high nip loads and withstand repeated cycles of loading and unloading.

Paper Machine Suction Rolls and Roll Covers

Training Time: 23 minutes

Though their design and construction are very similar, suction rolls perform several different functions on paper machines, depending on their position. They can be used to remove water from the sheet, transfer the sheet, improve dewatering in a press nip, dewater a felt, stabilize the sheet, or pull steam into the sheet. Roll cover selection should take into account the functions of the roll and the operating conditions.

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Air loading tubes are used to load seal strips against the roll shell; the seal strips seal in the vacuum in the vacuum box

Spherical roller bearings allow the heads and shell to rotate freely around the stationary vacuum box

Paper machine roll covers are typically constructed of rubber, polyurethane, a composite, or ceramic

Learning Objectives

  • Explain the purpose of suction rolls in the forming and press sections of a paper or board machine
  • Identify and describe the function of key components of a suction roll
  • Explain the importance of proper vacuum box and end deckle positioning in suction rolls
  • List the various types of roll cover materials and their typical applications
  • Explain the benefits of grooved and blind-drilled roll covers
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Paper Machine Suction Rolls and Roll Covers FAQs

Where are suction rolls typically located on a paper or board machine?
Paper and board machines are typically equipped with multiple suction rolls in the forming and press sections.

What are suction press roll shells constructed from?
Suction roll shells are typically constructed of bronze or stainless steel.

What is the flushing shower in a suction roll used for?
The flushing shower is used when the paper machine is down to clean and flush stock build up out of the vacuum box and the holes in the roll shell.

What are the most common roll cover materials?
Rubber and polyurethane are the two most common roll cover materials. Rubber is very versatile, while polyurethane is tough and wear resistant. These materials can be designed for use in many different applications.

Where are ceramic roll covers used?
Ceramic roll covers are extremely wear resistant and have very good release properties. They are often used on center press rolls.

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