GB669492A - Apparatus for casting hollow articles and preparation thereof - Google Patents

Abstract

669,492. Molding processes. HERMAN PNEUMATIC MACHINE CO. July 27, 1949 [July 29, 1948], No. 19784/49. Drawings to Specification. Class 83 (i). A mould for a cast iron pipe or other elongated article is made by filling with uncompacted sand, a flask of such a size that when the sand is correctly compacted to form an axial hole this has the diameter required, then centrifuging to densify the sand against the flask, and then compacting further. The filled flask is rotated about its axis to compact the sand sufficiently to allow a mandrel to be introduced axially which may be done after turning the flask from vertical .to horizontal position. The flask is then rotated and the mandrel moved against the sand wall to compact it and produce a hole of the desired diameter. The internal diameter a of flask required to cast a body having external diameter b may be obtained from the equation a<2>= S<1>/S (a<2> - b<2>), where S<1>/S is the ratio of the specific gravity of the compacted to that of the uncompacted sand. If this ratio is taken as 1.4 the equation becomes a=#3.5b<2>. The desired inner diameter of flask may be obtained by using an insert in a larger flask. The flask may be carried by a moulding and centrifugal-casting machine of the kind described in Specification 650,683.