The press roll of a paper machine

The press roll of a paper machine is the main component of the press section. The following is a detailed introduction to the press rolls of a paper machine:

I. Types

There are many types of press rolls for paper machines, mainly including the following:

Plain roll press

Both ordinary presses and straight-through presses use plain roll presses. In the structure of a plain roll press, the upper roll is a stone roll and the lower roll is a rubber roll, and both rolls have smooth and even roll surfaces. The stone roll is a common type of plain press roll, usually made of a material that readily releases from the paper, such as granite. At present, most artificial stone made from a mixture of rubber and quartz sand is used instead of natural granite as the upper press stone roll. The lower roll of a plain roll press is a rubber-covered cast iron roll. Rubber covering not only provides corrosion resistance for the press roll, but more importantly provides good elasticity.

Fabric-lined press

This includes two methods, namely fabric-lined press and sleeve-net press. In fabric-lined pressing, a plastic net with relatively large mesh is additionally lined inside the press felt, thereby reducing the fluid pressure in the nip and facilitating dewatering. In sleeve-net pressing, a net sleeve is fitted over the lower plain rubber roll or suction roll, and the two ends of the plastic net sleeve are fixed with segmented pressure rings or full-circle pressure rings.

Suction press

It is mostly used in medium- and high-speed paper machines. The upper press roll of a suction press is a stone roll, and the lower press roll is a suction press roll. The structure of the suction press roll is basically the same as that of the suction couch roll. The roll shell is cast from bronze or stainless steel, and the thickness of the roll shell is determined by the required stiffness and strength.

Grooved press

The grooved press roll is an improved press roll developed in the late 1950s. The structural form of the grooved press is also that the upper roll is a stone roll and the lower roll is a rubber roll. The open area ratio of the grooves is an important parameter affecting dewatering, and an open area ratio of 16% is generally considered better.

Blind-drilled press

The blind-drilled press roll is another improved press roll developed in the 1970s on the basis of the grooved press roll. The blind-drilled press roll is also covered with rubber or polyurethane on an iron roll core, and blind holes are drilled on the rubber-covered surface. The open area ratio of the blind-drilled press roll is about 25%–30%, and the hole volume is about 5 times larger than that of the grooved press roll, so it can hold more press water.