To obtain a piercing device in which the tip of a plug is prevented from eroding by using an analysis model in a piercing method of a seamless metallic tube.
In a piercing device, the temp., which is measured with a temp. measuring device 7, at the tip of the plug 3 just after appearing from the rear end part of a material 6 to be rolled is inputted to a calculating means 8. With the calculating means 8, in the case the measured temp. is less than a predetermined plug fusing temp., the signal for using the plug for the next rolling is sent to a plug cooling device 10 and piercer controller 9 without changing a plug cooling condition and piercer piercing condition or by shortening only the plug cooling condition. And, in the case the measured temp. is not less than the predetermined plug fusing temp., the temp. of the tip of plug is calculated under a condition properly changing the plug cooling condition and piercer piercing condition in a prescribed range and signals of the plug cooling condition and piercer piercing condition for making the calculated temp. less than the predetermined plug fusing temp. are sent to the plug cooling device 10 and piercer controller 9.
YAMAKAWA TOMIO
URAYAMA TAKESHI
WADA NOBUHIKO
WANAKI JIYUICHI
OKUYAMA KO
KITANI SHIGERU
