Measurement of metal–roll interface during metal rolling using normal and oblique ultrasonic reflection

It is important to monitor the roll bite interface during metal rolling to maintain the product size and homogeneity so as to minimize the material wastage. However, the harsh nature of cold rolling makes installation of sensors in metal roll for industrial applications difficult. The present study used a novel ultrasonic measurement technique whereby an ultrasonic signal went through an external sensor layout arrangement to study the metal-roll interface. The reflection coefficient obtained from the roll-strip interface at 0° to the roll surface (normal ultrasonic measurement technique) and 19° (oblique ultrasonic measurement technique) were modelled and experimentally investigated on an instrumented pilot metal rolling mill. Variances of 6.4% and 8.8% were obtained in the reflection coefficient of the techniques from experimental and modelling approaches, respectively. This showed that both techniques could be used to study the effect of the angle of incidence wave on the reflection coefficient.