To previously prevent work failure by comparing a position detected by a position detecting means on an after completing the setting of a tail stock with a stored position, and detecting abnormality when the compared result is not coincident.
When a motor current becomes a designated value, in other words, when pressing force of a tail stock 13 becomes designated pressing force, a low speed advance of the tail stock 13 is stopped, the setting of the tail stock 13 is completed, an output signal of a u-axis rotary encoder 29 at this time is stored as a setting completing position, and an output value of an ammeter 31 at this time is stored as a setting completing electric current value. A tail stock position is monitored by a signal outputted by the u-axis rotary encoder 29, the tail stock position by the signal outputted by the u-axis rotary encoder 29 is compared with a stored setting completing position, and when the compared result is not coincident, abnormality is detected.
MIZOZONO MASAAKI
ITO MASARU
AWAI MASAHIRO
MARUYAMA ATSUSHI
ICHINOMIYA HISANORI
KAWASAKI HEAVY IND LTD