EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

The target of this work has been to in detail measure the conditions inside the roll gap during hot and cold rolling. For this purpose rolling was done using an instrumented work roll. The purpose was to measure contact length, contact force distribution, friction coefficient and heat transfer coefficient. The work roll used three contact sensors, two for measuring the contact loads and one for the measurement of the heat transfer inside the roll gap during rolling. One of the sensors is the “Rollsurf” sensor designed to minimise the penetration of material during rolling. The signals were transferred wirelessly. The measured contact length became larger than the contact length calculated using the most commonly used theoretical estimations. A better agreement is obtained if the elastic springback of the strip is regarded. The contact force distribution varies for different types of passes early, mid and late passes. For early passes the peak pressure is close to the entry side and for late passes the pressure peak is close to the exit side. This tendency is considerably weakened if the work roll is idle. A friction coefficient is calculated using the ratio of the measured tangential and the normal force. The result indicates that the friction coefficient strongly varies through the roll gap having high values at entry and exit and low values in between. The measurement of contact temperatures and calculation of HTC reveals that the heat transfer is strongly affected by the pass conditions. The measurements have provided information that will help to better understand the complex relationships inside the roll gap. This knowledge can be used for improving basic rolling models for friction and wear as well as models for heat transfer in the roll gap.