Patent ID: 8857236

Claim:
A forging device equipped with a die having a shaping hole having upper and lower open ends and a helical blade portion formed on an inner peripheral surface of the shaping hole, a punch arranged on an upper side of the shaping hole coaxially with the shaping hole, whereby a forging material is driven into the shaping hole from above by the punch to form a forged article having a helical groove corresponding the blade portion on an outer peripheral surface thereof, the forging device comprising: a back pressure generation mechanism arranged on a lower side of the shaping hole non-rotatably about an axis, and a back pressure transmission mechanism arranged to transmit a back pressure by the back pressure generation mechanism to a metallic material as the forging material to be driven into the shaping hole, wherein the back pressure transmission mechanism includes a rotation-side transmission member arranged rotatably about the axis, and a non-rotation-side transmission member arranged on a lower side of the rotation-side transmission member non-rotatably about the axis, a lower end of the rotation-side transmission member is arranged so as to come into contact with an upper end of the non-rotation-side transmission member rotatably about the axis, the rotation-side transmission member includes a back pressure plate for restraining a lower end of the metallic material at the time of shaping, an engaging dented portion is formed on an outer peripheral portion of the back pressure plate corresponding to the blade portion, the back pressure plate is arranged in the shaping hole in a state in which the engaging dented portion is engaged with the blade portion slidably in an up-and-down direction, and when the forging material is driven into the shaping hole and the back pressure plate is pressed downward by the metallic material, the engaging dented portion of the back pressure plate is guided by the blade portion and thereby the back pressure plate descends while rotating about the axis, and a back pressure by the back pressure generation mechanism is applied to the metallic material via the back pressure transmission mechanism.