PRODUCTION OF HOLLOW CASTING HAVING IMPROVED QUALITY

摘要

PURPOSE:To produce homogeneous and minute crystal grains by smashing crystallized crystal, and to obtain a good quality hollow casting having good surface characteristics and dimensional accuracy without shrinkage at end period of the solidification, by inserting and rotating a core in the molten metal during cooling in a mold and drawing out it just before finishing the solidification. CONSTITUTION:The mold 12 in a resistance heating furnace 5 of a vacuum vessel 1, by which a shutter 2 made of Mo, etc., is opened, is ascended into a water cooling outer cylinder 7 in a cooling room 6 by a lifter 11 and also the core 9 is inserted into the molten metal in the mold. The core 9 is at first rotated at low speed by a motor 10 and in succession, rotated at high speed to smash the deposited crystal during cooling and make it to minute. Just before finishing the solidification, the rotation is stopped and the casting is drawn out. The hollow cooling solidified casting is no shrinkage at end period of the solidification by the centrifugal force, and the minute and homogeneous hollow casting, having the good surface characteristics and the dimensional accuracy, is obtd.