| 摘要 |
Powdered metal is encased in an elongated flat-ended airtight deformable can by pouring it through a tubular filling stem through which the interior of the can is then evacuated to avoid subsequent oxidation of the contents thereof, and the stem is then sealed to retain the vacuum. The powdered-filled evacuated can is then heated to a high temperature of approximately 2,100 DEG F. for about 1 hour, and while at that temperature is first compressed longitudinally to a high density in an extrusion containing a longitudinal extrusion chamber with a lateral extension thereof which causes it to undergo extrusion laterally into said lateral extension of the extrusion chamber located within the die cavity. This action kneads the densified metal and obtains a so-called "grain flow" which improves the metallurgical properties thereof. Meanwhile, the peripheral portions of the opposite ends of the can move into clearance spaces surrounding the ends of one or both of the punches, thereby preventing crinkling of the can. The walls of this dense metal-filled can are then removed by machining or pickling, along with the deformed peripheral end portions thereof containing less dense metal powder. Thus, there is produced a substantially solid, laterally extended metal billet, the shape of which can be varied in accordance with the variation of the shape of the lateral extension of the extrusion chamber within the die cavity, for example circular (FIGS. 6 and 7), rectangular (FIG. 14), cruciform (FIG. 15) or circular with a central boss or bosses (FIGS. 20 and 21). |
