Polymer covered cylindrical rolls are typically used in different paper machine sections like in calenders and in coating units. The main reason for the use of soft-coated rolls is that by using the soft rolls the contact area becomes larger. Strongly loaded line contact causes deformations and heat generation in the polymer cover. In paper production process impurities, like paper pieces, may catch on the surface of the roll. Impurities cause locally larger deformation in the cover. The local deformation produces a higher local temperature area, which can cause cracks in the cover, to loosen the cover from the base and to fracture the cover locally. If a local failure happens the fragments of the cover can damage also the other rolls. In this paper an operation monitoring system for on-line monitoring of roll cover is presented. The system is installed in a laboratory pilot roll installation, where the rolling contact consists of a hard and a soft roll. The measurement system consists of on-line measurement of acoustic emission (AE) of the roll. Additionally the temperature distribution of the roll, the ploymer cover and the position angle of the roll are measured. The measurement signal is transferred from the rotating roll via wireless local area network (WLAN) to the measurement computer. The measurement control computer is connected to the LAN of the laboratory and the measurements can be followed and analyzed with different computers and also via Internet. The paper describes the principles of acoustic emission signal processing and analysis and the construction of the wireless Ethernet-based operation monitoring system.

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