PURPOSE: To manufacture a blank pipe having little fluctuation of wall thickness through the later rolling work following to the beginning stage, by determining the pattern of wall thickness fluctuation from the result of the rolling work for several blank pipes at the beginning of the rolling work carried out by the Mannesmann plug mill, and by correcting the roll gap depending on this pattern.
CONSTITUTION: In the case of continuously rolling many blank pipes by the Mannesmann plug mill, the distribution of the wall thickness of several blank pipes 1 obtained at the beginning stage of the rolling work is operated by the arithmetic control 8 according to the signal sent from the wall thickness measuring device 7 arranged on the downstream side, etc., of the rolling roll 2. According to the result of this operation, the pattern of the wall thickness fluctuation is determined and is stored in the memory. In the following rolling work, the roll gap is controllingly corrected according to said pattern of the wall thickness fluctuation at the same time as the blank material for the pipe is bitten by the roll 2. By this rolling method, the blank pipe having uniform wall thickness is manufactured.
HORI MITSUAKI
WADANO KATSUMI
TANAKA MEGUMI
