PURPOSE: To obtain an operating screw rod for an automobile jack for firmly connecting both an engaging piece and the screw rod.
CONSTITUTION: A method of manufacturing comprises a part molding process 1 for molding a screw lever having an external thread part from a suitable location over to a tip and an engaging piece having an engaging groove or engaging hole respectively into a separate unit, part holding process 6 for holding the engaging piece to the first electrode unit on the other hand to the second electrode unit so as to protrude a rear end part of the screw rod by a required amount and a resistance welding process 14, next after an electrode unit moving process 12 for moving at least the first or second electrode unit by drive force of a driving means, for swelling a protruding end part in a flange shape so that the engaging piece bites in the protruding end part of the screw rod by flowing a current in these engaging piece and screw rod while an external wall surface of the engaging piece is brought into pressure contact with a protruding end face of the screw rod.
ITAKURA FUMIO
OKADA MASARU
