GB575801A - Improvements in destructible forms particularly for the manufacture of fuel tanks and other articles - Google Patents

Abstract

575,801. Cores for moulding. GRENEKER, L. L. March 14, 1944, No. 4755. Convention date, March 30, 1943. [Class 87 (ii)] A hollow destructible core, which may be used for moulding indiarubber fuel tanks, is made of plaster of Paris or other frangible material reinforced by plasterboard and by a rope which is embedded in the frangible material, the walls of the core being so thin where the rope is embedded that pulling out of said rope breaks the form into pieces which may be withdrawn from the fuel tank through an opening in the latter. Specification 574,211 is referred to. Fig. 9 is a section through a corner of a three-part mould, Fig. 8, in which the core has been cast, the core comprising plaster 36 in which cheesecloth or paper burlap reinforcement 39 is embedded, plasterboard 53, 56 and rope 62. The outside of the core may be covered with paper glued thereto ; or paper or cloth may be laid first in the mould to form the outer surface of the core, in which case the cheesecloth &c. may be omitted. The plasterboard may be in sections small enough to pass through the fuel tank opening after the core has been disrupted, or the sections may be too large to pass through, in which case they are broken into smaller pieces in the tank. To facilitate breaking, the sections may be cut partly through, as along lines 49, 50, 51, Fig. 6, which is a plan view of the lower part of the mould with the core cast therein. To hold the plasterboard 53, 54 firmly in contact with the curved mould walls, sticks 58 may be wedged therebetween until the plaster sets. Additional reinforcement comprising rope, fabric and plaster may be applied to the inside of the core. Fig. 3 is a view of the underside of the lid 14 of the mould. The lid includes a boss which forms an opening in the core. As shown, the rope is disposed in coils and has free ends 62a which are grasped to disrupt the core. The mould base comprises two parts 20, 21, held together by clamps 30, 31, and lugs 24 fit into recesses 25 in the lid. The two core parts are cast in the basÚ and the .lid, and the latter are assembled, whereupon the core parts coalesce.