公开(公告)号：JPH11190727A

公开(公告)日：1999-07-13

申请号：JP28464398

申请日：1998-10-07

Applicant: BELOIT TECHNOLOGIES INC

Inventor： RICHARD L FARNSAID ,  GORDON R VOLL ,  DENNIS A WHITE

IPC: G01N29/04 ,  D21G9/00 ,  G01N29/11 ,  G01N29/10

Abstract: PROBLEM TO BE SOLVED: To provide a method capable of ultrasonically detecting a position and a depth of a material defect at a cast outer shell of a dryer. SOLUTION: Radially spaced calibration holes 46 are opened in parallel to an outer surface of a cylindrical outer shell 36 of dryer roll. As the shell 36 is rotated, an interval and angles of ultrasonic converters 24 crossing the shell 36 are regulated, and the converters 24 are mounted at a fixture 26 in which coupling media are packed. A time of advancing a signal from the converter 24 and returning the signal to the converter 24 and a depth of returning the signal are calculated by a computer 60. It has been discovered that a clear signal corresponding to the hole 46 at 1 inch at a maximum from the surface is obtained by regulating an ultrasonic wave transmitting angle. This angle is about 23 degrees perpendicularly to the surface of a cast material 20. After its calibration is finished, the converter is crossed at the surface of the cast material. Stored data can be used in the case of maintaining a dryer roll formed of the cast material.