PURPOSE: To maintain easily a plug bar holding device and to reduce initial investment by unifying a connecting device, a plug-bar-position adjusting device, and a piercing-reaction-receiving hydraulic cylinder to the rear end part of a plug bar, in a seamless steel pipe piercing installation.
CONSTITUTION: A steel material 8 to be rolled is formed into a hollow pipe stock 11 for a seamless pipe by piercing the material 8 with the aids of rolls 10 for forming the outer diam. of pipe and a plug bar 1. A connecting fixture 20 of plug bar, a device 21 for adjusting a plug position, and a hydraulic cylinder 22 for receiving a reaction at the time of piercing, in this device, are unified to the rear end part of the plug bar 1 for piercing, and are arranged on rails 33 of a main beam 5 to make them possible to reciprocate by a draw back cylinder 34. When the material 8 is pierced to form it into a hollow pipe stock 11 shape by a material push-in device 9, the rolls 10, and the plug bar 1; the plug bar 1, the device 21, and the cylinder 22 can be retreated in one body, and plug bar 1 is easily held by a simple installation.
ONOHARA HARUO
TATEYAMA SHIGEHARU
TAKAHASHI KATSUSHI
OOMORI MASAKATSU
AZEZAKI MASAYUKI
HITACHI LTD