PURPOSE: To detect generation of the anomalous thickness deviation in the hollow shell, by measuring the surface temperatures along circumference of the hollow shell at multiple points, by operating the maximum temperature deviation from these measured values, and by comparing this maximum temperature deviation with previously set allowable value of the temperature deviation.
CONSTITUTION: The heated round billet B is fed in the longitudinal direction by the piercer and a hollow shell HS under the condition of being pierced along the axial line is obtained; on the run-out side of the piercer, the surface temperatures of this hollow shell HS along its circumference are measured at multiple points by the temperature sensor TS. The measured values are sent to the data processor D, which then operates the maximum temperature deviation along the circumference of the hollow shell HS. At the same time, this maximum temperature deviation is compared with the previously set allowable limit; if the maximum temperature deviation exceeds the allowable limit, the generation of an anomalous thickness deviation is judged.
NISHIKAWA KOUICHIROU
ARIMATSU KANJI
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