Optimisation of the roll geometry for production conditions

In the coating and calendering processes in the paper industry the rolls are in direct contact with the paper and give it the final surface structure and finish. The knowledge about the relation of the roll geometry to the paper quality and to the runnability can be used to improve the operation of the rolls and the machine. Similar methods can be applied to steel mill rolls even though the rolling process and the rolls are different. The importance of the roll geometry for the quality of the end-product was seen in the end-product analysis results. The geometry components of the individual rolls in coating and in calendering sections were identifiable in the paper analyses. Similar results were observed in the rolling process in the steel mills. The major difference between the rolls in the paper and steel industry was that the measured paper quality variations in the paper industry correlated with the static and dynamic geometry errors of the rolls, but in the steel industry the observed variations correlated with the positions of the key grooves in the bearing arrangement of the backup rolls. A cost effective solution to the geometry related problems would be to find a way to reduce the observed geometry errors in the current rolls or to reduce their effects on the end-product. This was the main target of this research. Methods to achieve this were developed. After the introduction of a roll geometry measurement device, a compensation machining technology was developed and the static geometry of the filled calender rolls was improved. The development of the dynamic roll geometry measuring device for the geometry errors of the fast rotating rolls led to the the compensation method of the dynamic geometry errors of the backing rolls. After the development of an in-situ run-out measurement device for fast rotating rolls similar attempts were made to reduce the thermal run-out of thermo rolls of calenders. The drawbacks in the experiments demonstrated the need to deepen the understanding about the roll behaviour. An ultrasonic measuring device was used as a roll shell measuring device. With the measured information detailed roll models could be created, which the secondary target of this research. In the steel industry the developed measuring and machining methods were used to compensate the spring of the bearing arrangement caused by the key groove. This reduced the variations of rolling force and of steel strip thickness. With all the presented results it can be concluded that both targets of the research could be reached: effects of the geometry errors were reduced and detailed roll models were created. This enables an optimisation of the roll geometry in the production conditions.