Oct 16, 2018
Airides are used in a variety of pulp and paper production machinery applications. One reason for their wide use is the minimal need for maintenance. In general, no maintenance is required on the airide unless the rubber gets hard and brittle or it starts to leak.
However, high temperatures, exposure to process chemicals, heavy loading and damage from contact with moving machinery are causes for eventual maintenance or replacement of airides. Periodically, airides should be inspected and adjusted or replaced as required.
An airide is a rubber/fabric bellows which contains a column of compressed air. The bellows itself is merely the container as the force or support exerted is performed by the air column. Airides are either two ply or four ply and are manufactured by a vulcanization process. The figure shows the two ply construction.
Each ply is fabric reinforced rubber with the cords set at a bias to each other. An inner rubber liner and an outer rubber cover complete the envelope.
The bellows is attached to the mounting plate using bolts through metal bead rings. If the airide has more than one convolute, the convolutes have a steel girdle hoop molded into the bellows, as seen in the figure below.
As a typical example, the first press top roll, second press roll and center roll doctors are airide loaded.
To adjust the airides:
The longest possible flexible life for the airides will be obtained when the parts are used in such a manner that the splice is not overly stressed. The spliced area is marked with a yellow dot in the area that is to be flexed the least. This will occur when the yellow dot falls on the inside of the arc.
To minimize the possibility of air leakage around the beading on the airide, use the following assembly procedure:
Airide maintenance and other paper machine maintenance topics are covered comprehensively in Valmet's Paper Machine Maintenance School. For more information on maintaining your machine line, contact your Valmet representative.