Enclosed Die Forging Using Die Set

Enclosed die forging of automobile parts such as cross pins and tripods necessitates two punches moving oppositely with the same velocity. Although multi-axial presses are constructed for this purpose, simple methods on ordinary cold forging presses are requested. To realize an equivalent motion for enclosed die forging on a press with a single driving axis, a die set using a pantograph links is invented. In this die set, the upper punch is driven with the press speed and the lower punch is kept still. The die is mounted on the middle plate fixed to the intermediate hinges of the pantograph, and as a result the relative velocities of the punches satisfy the requested relation. The die is usually divided horizontally for extracting the formed product from the die cavity. It is shown that vertical division of the die can eliminate the parting lines on the extruded rods with good circularity.