GB538512A - Improvements in or relating to molds for casting purposes - Google Patents

Abstract

538,512. Foundry moulds. STEVENS, A. H. (Aluminum Co. of America). Dec. 7, 1939, No. 31724. [Class 83 (i)] A permanent mould for casting aluminium or other pistons or other cap-shaped article having thin and thick portions comprises two parts recessed on their meeting faces to form one or more cavities with axes horizontal and a sprue extending across the axis or axes and communicating with the base or thick forming parts only of the cavities. The mould has a table 16 carrying a frame 18, bolted at 50 and resting on feet 51 to allow expansion due to heating. Two slides 20, 21 move on horizontal guides 53, 55, Fig. 5, and 57, Fig. 4, of the frame, these guides also being arranged to allow expansion. Each slide has a cavity in which is arranged two dies 28, 29 recessed on their meeting faces to form the exterior of two pistons with their axes horizontal and in the parting plane. In the slides are also formed a sinuous sprue 36, a riser 35 and gates 37, 33. The frame 18 also carries a block 38 with holes 39, 40, to guide the cores, and countersinks 41, forming part of the casting cavities, whereby the castings are supported after the withdrawal of the cores and dies as shown in Fig. 4. The cores each comprise a wedge 42, operated by a rack 47 and a pinion 141, and segments 43, moved laterally by toggles, and shafts 45, 46. The slides 20, 21 are operated by toggles and shafts 25, 27. The shaft 70, Fig. 2, on which the pinion of the upper rack 47 is mounted, is driven through a lost motion device 71 by the lower shaft 67, which has a pinion engaged by rack teeth 59 on the piston rod of the actuating cylinder 58. Teeth 83 on this rod act, through a gear 81, to reciprocate a cam plate 92, Fig. 8, having formations 86, 87, 94, 194 to act on crank arms of the shafts 25, 27, 45, 46 in succession when stripping the casting. By reason of the device 71 the wedges 42 are also withdrawn successively. The bearings of the shafts 25, 27, 45 and 46 may be elongated in a direction at right angles to the mould axes to allow expansion. In a modification the shafts 67, 70, Fig. 13, are integral, all the shafts 25, 27, 45, 46, and 70 are rotated by handles H instead of by power, the wrist pin cores 32 are withdrawn slightly, before the dies 28, 29 begin to move, a wedge clamp 137 is mounted on the part 20, and the sprue is sinuous in the parting plane and forms two traps A, B, Fig. 14, for light inclusions. The mould may be heated before casting operations are commenced and may be cooled internally or externally between each operation to optimum temperature. Specification 538,867 is referred to.