| 摘要 |
1518937 Comminuting at low temperatures impact pulverizers BOC INTERNATIONAL Ltd 18 Sept 1975 [19 Sept 1974] 40819/74 Heading B2A Metal swarf is cooled to -20‹C or below and preferably to between -40‹C and -180‹C, by direct or indirect contact with a cryogenic liquid (preferably liquid nitrogen) and accelerated against a stationary target, whereby the swarf is reduced to powder. The apparatus may be a vaned rotor 8, 10 impelling the swarf against a hard metal target 12, Fig. 1, liquid nitrogen being injected by a nozzle 16. The clearance between vanes and target may be adjusted. In a second embodiment a screw conveyor feeds the swarf into a hopper 20 and thence it falls into a vaned rotor 26, 28 Fig. 2. A third embodiment employs beaters of progressively increasing length Fig. 3, not shown, or beaters in a chamber including a sieve 74 in the outlet Fig. 4. In a further embodiment the swarf is drawn into a venturi tube 82, 84, Fig. 5, in which flows a high velocity stream of liquid and gaseous nitrogen or a secondary fluid cooled by liquid nitrogen and the entrained swarf is comminuted by impact with a target 86. |
