Patent ID: 7562578

Claim:
A method for determining surface defects such as cracks, spalling, on work rolls ( 2 a ) of a rolling mill ( 1 ) that are supported with backup rolls ( 2 b ) in housing posts ( 3 ), by the use of ultrasonic waves ( 4 ), wherein the roll ( 2 ) in which defects are to be detected is tested in its installed position, the method comprising the steps of firmly pressing an ultrasonic transducer ( 5 ) and an ultrasonic receiver ( 6 ) against the surface ( 2 e ) of the roll for the duration of the test, and introducing ultrasonic transverse waves ( 4 a ) with a frequency of about 0.5 to 2 MHz at one end ( 2 c ) of the roll and receiving the ultrasonic waves at the other end ( 2 d ) of the roll, where the ultrasonic waves ( 4 ) are conveyed via a piezoelectric element ( 33 a ) through a core part ( 27 ) of transparent plastic and an adjacent silicone filling ( 32 ) to a roller-shaped contact body ( 17 ) made of steel, which is pressed against the roll surface ( 2 e ) at one end of the roll barrel.