METHOD FOR MANUFACTURING A INNER DRUM UNDER DRIVE CLUTCH AND COLD FORGING DEVICE FOR MANUFACTURING THE INNER DRUM UNDER DRIVE CLUTCH

摘要

The present invention relates to a novel method to manufacture an inner drum under drive clutch and a cold forging device to manufacture the same using a seamless pipe instead of a round bar in order to achieve preciseness of shaping while reducing process costs and manufacturing costs. The method to manufacture the inner drum under drive clutch comprises: a step of preparing a pipe of a hollow seamless shape; a first forming step to cold forge the prepared pipe in order to extend a length and reduce an outer diameter for a body part forming portion; a second forming step to grow to simultaneously increase a thickness and the outer diameter by upsetting a flange part forming portion on the pipe formed in the first forming step; a third forming step to perpendicularly bend the flange part from a center of the material by cold forging the pipe formed in the second forming step; and a machining step to process the pipe formed in the third forming step in order to form an outer and an inner surface of a body portion and the flange part within a tolerance range.