| 摘要 |
<p>570,166. Working aluminium &c. alloy scrap. GROOM, E. J. Nov. 29, 1940, No. 17073. [Class 83 (iv)] [Also in Group II] Aluminium- or magnesium-base alloy scrap is recovered by freeing from cutting oil, free iron &c., comminuting and subjecting to pressure in a die, hot or cold. This avoid's the formation of undesirable combinations of alloying materials. Aluminium scrap may be comminuted so that 80 per cent will pass a 200-240 I.M.M. sieve and pressed, hot, e.g. at 350-450‹ C., or cold, in a die at 5-80 tons per sq. in. Magnesium scrap may be comminuted to pass a 200 I.M.M. sieve and subjected to a pressure of 10-30 tons at 250-300‹ C. The scrap is preferably comminuted in a ball mill to produce angular grains. If the powder is made by stamping it is then treated by two air-screw streams in a chamber to convert the lamellar grains to a spherical form. The powder may be adjusted to desired analysis by adding selected powdered scrap and may be heated by heating the die, by passing an electric current through the mass, or by induction. The die.may have the shape of the article required or a pressed block may be machined, finished pressed, or extruded. In this case the first pressing is at a low pressure, e.g. 5-6 tons per sq. in.</p> |
