Method of and machine for extruding

The method of extruding a billet of high strain rate sensitive alloy which comprises:

• (a) bringing a billet of such metal to its extruding temperature;
• (b) forcing the metal through an extrusion die that is mounted on a platen of an extrusion press of the type wherein pre-tensioned tie rods exert a pressure to hold the platen against being moved as a unit by the metal being extruded;
• (c) characterized by the fact that the pretensioning of the tie rods is in an amount greater than the maximum opposite pressure exerted on the tie rods by the platen as a result of the metal being extruded through the die, and the pre-tensioned rods are held in tension by stop members against which they bear and which stop members maintain their position with negligible variation during the extrusion notwithstanding the said opposite maximum pressure exerted on the rods by the platen during the extrusion, thereby eliminating stretching of the tie rods by the forces exerted thereon by the platen during the extrusion and thus eliminating the effects that such stretching would have on the metal flow through the die, the billet being a casting that has been cooled from the temperature at which the metal was cast to its extrusion temperature in two successive stages namely a rapid chill casting until the billet has solidified in the mold but is still above the temperature for extrusion and the billet being then transferred to a tempering oven which is at a temperature to homogenize the casting and bring it down to and maintain it at its said extruding temperature.