Abstract: An apparatus for working both ends of a workpiece at a time. The workpiece, typically in the form of a bar or a tube, is successively shaped by pre-shaping die means, shaping die means and finish-shaping die means, each of which comprises a pair of dies for simultaneously working both ends of the workpiece to a predetermined configuration. The dies in each pair are movable toward and away from the both ends of the workpiece, respectively, in accordance with the operation of a pair of hydraulic devices. A pair of knockout rods respectively slidably received in cylinders of the hydraulic devices cooperate to support the workpiece while the latter is progressively shaped. One of the knockout rods is fixed to one of the dies while the other knockout rod is held afloat relative to the other die by a hydraulic device, so that the workpiece is allowed to stretch to a full available length only at one end thereof on the afloat knockout rod side.

Abstract: An electrical upsetting method for upsetting a cylindrical metal material, which is durable against wear and tear due to high temperature as well as vigorous friction under heavy pressure during the upsetting work, wherein a space gap is provided between the outer peripheral surface of the workpiece and the inner peripheral surface of the shaping die to prevent the die from direct heat from the workpiece generated by electric conduction across the electrodes, or wherein a space gap is provided between the outer peripheral surface of the anvil electrode and the inner peripheral surface of the shaping die, and an inert gas is filled in the space gap to protect the die from oxidation due to its exposure to the external atmosphere, or air, as well as to maintain the die in a cooled condition by the inert gas.