JPS57134230A - Helical gear forming device - Google Patents

Abstract

PURPOSE:To lengthen the life of a punch and enable maintaining of dimensional accuracy of a helical gear by providing a unified punch in the upper and lower parts instead of split inner and outer punches and moving up and down and rotating a core. CONSTITUTION:A cylindrical material 11 is placed on a rotating lower punch 12 that has a helical groove on the outer periphery and a key way on the inner periphery, and inserted between a fixed die 14 having a helical groove on the inner periphery and a rotating core 15 provided with a key way on the outer periphery with descent of a supporting stand 13 of the punch 12. When the bottom of the supporting stand 13 is brought into contact with a base plate 16, rotation of the punch 12 that came down while rotating along the helical groove of the die 14 is checked. Next, an upper punch 17 having a helical grooves on the outer periphery goes down while rotating, and the material 11 is compressed and formed in a space enclosed by the die 14, core 15 and punches 12, 17. On arriving at the bottom dead point, the punch 17 makes reversed rotation and ascends and the supporting stand 13 ascends successively. At this time, a helical formed body 18, the core 15 and punch 12 go up while rotating in a body, and taking-out of the formed body 18 is made possible.