ELONGATION DRIVE DEVICE OF STRETCH ROD IN STRETCH BLOW MOLDING MACHINE AND BOTTOM-TYPE LIFTING DRIVE DEVICE

摘要

The elongation drive device of a stretch rod provided in a stretch blow molding machine and a bottom-type lifting drive device are simplified, downsized and rendered durable by using both a magnetic screw shaft and a magnetic nut member that smoothly permit a rotation-linear motion conversion in a non-contact condition. A nut member and a screw shaft provided in a elongation drive device (6) and a lifting drive device (30) are respectively formed of a magnetic nut member (65,116) and a magnetic screw shaft (66, 117) in which N-pole magnetized strips and S-pole magnetized strips are spirally and alternately applied at the same pitch to the inner peripheral surface of a cylindrical body and the outer peripheral surface of a shaft material. The magnetic screw shaft is inserted into the plunger (61, 115) of the cylindrical body internally integrated with the magnetic nut member so as to face the magnetic member with a specified clearance therebetween and with the like poles in the like direction.