PROCESS AND APPARATUS FOR 3D CIRCULAR EQUAL CHANNEL ANGULAR PRESSING

摘要

The illustrated embodiment of the invention is a device for nano-structuring of bulk material in the form of circular rod so as to reduce the grain size. The bulk material in the form of circular rod is extruded repeatedly through the 3D ECAP die until the grain size of virgin material (few hundred micrometers) is reduced to few hundred nanometers. The device comprises two vertical halves of the said die having a plurality of inter connected passages through which the said circular rod is directed for the said nano-crystalline formation, two hollow circular rings positioned externally at the top and bottom of the said dies for holding the said two vertical halves of the die in contact during the extrusion process, four removable fasteners connecting the said top and bottom circular rings at pre-determined positions, an output orifice in the stationary constraint die having substantially the same cross section as the cross section of the passageway and an input orifice for feeding a solid circular metal to be pressed into a portion of the passageway so that the circular metal is carried in the groove by frictional drag in the direction towards the said output orifice and is thereby extruded through the output orifice and without any substantial change in cross section. Fig.1