Patent attributes
A flaw detection apparatus and flaw detection method for automatically detecting the occurrence of a flaw in a mother tube manufactured by rolling a hollow shell using a mandrel mill are provided. A flaw detection apparatus (100) according to the present invention includes a wall thickness gauge (1) which is installed on the exit side of a mandrel mill (M) and which measures the tube wall thickness in each of the reducing directions of a hollow shell (P) in the #1-#5 stands of the mandrel mill, rolling load measuring devices (2) which measure the rolling load in the #1-#5 stands, and a decision unit (3) which determines whether there are flaws in the mother tube based on the measured value of the tube wall thickness in each of the reducing directions of the hollow shell (P) and the measured value of the rolling load in each stand. The decision unit (3) determines that a flaw has occurred in the mother tube when the measured value of the tube wall thickness in any of the reducing direction in the #1-#5 stands locally varies by at least a predetermined amount and the measured value of the rolling load in any of the #1-#5 stands locally varies by at least a predetermined amount.
