Patent GB-767597-A (GB)
Title: Improvements in or relating to shell molding apparatus
IPC: B22C23/00
Filed: 1954-03-02
Abstract: 767,597. Moulding-machines. SHALCO ENGINEERING CORPORATION. March 2, 1954 [March 6, 1953], No. 6071/54. Class 83 (1). Shell-moulding apparatus comprises a pair of spaced dump-boxes having corresponding open ends and each provided with a patternsupport receiving a pattern thereon, means hingedly securing said supports to said dumpboxes for moving the pattern from closed positions, extending across the open-ends, to open positions spaced from the ends, a curing oven positioned between the dump-boxes and movable from a position to heat the pattern on one of the supports when said support is in open position, means swingably supporting the dump-boxes for movement through 180 degrees for depositing moulding-material on said patterns, and means for so rotating the dumpboxes. Dump-boxes A, B, Figs. 1 and 2, are swingably-supported in a frame 9. Arms 11, 12 extend from each box and rotatably receive a shaft 15, to which is non-rotatably secured a pattern-support 16 comprising a frame 22 positioned between legs 17, 18, preferably rigidly, but alternatively on pivots 24, 25, so that it may be vibrated to strip the mould. The pattern-support may be swung on the shaft 15 to close the open end of the dump-box, for example B, by sprockets 35, 37, chain 36 and windlass 40, clamped into position by toggleclamps 42, and the assembly of dump-box and support inverted by continued clockwiserotation of the windlass, Fig. 3. The clamps may be automatically actuated by their engagement with a yoke attached to the frame 9 as the dump-box rotates, Fig. 35 (not shown). The dump-box may then be rotated counterclockwise to return it to upright position, the pattern-support unclamped and swung to openposition, and the shell-mould 49 thereon cured by an electric-oven 50. The oven is movable on wheels 60 between the two pattern-supports, its end-walls being cut away to allow its movement over the moulds. In a modification, Fig. 9, the oven is supported by a parallellinkage for movement between the patternsupports. Each pattern comprises spring- loaded ejection-bolts 62, Figs. 1 and 4, which, for ejection of a cured mould, are forced upwardly by a plate 68 actuated by a piston 69 carried by a wheeled-device 67 movable between the two pattern-supports. Flanges 78, 79 of the device engage clips 76, 77 of the associated pattern-support to resist upward movement thereof during ejection. In a modification. Fig. 6, the oven and the ejectiondevice are connected by a chain 85, so that as the oven moves to cure a shell on one patternsupport, the ejector moves to position itself to eject the previously-cured mould from the other support. In this case the flanged members of the ejection-device which restrain the patternsupport from upward movement are spring- loaded and actuated by movement of the ejector-plate, being normally held out of engagement so that the pattern-support may be swung to closed position on the dump-box when the ejection-device is in position, since the latter cannot be moved therefrom while the oven is in curing position over the other patternsupport. In a preferred process of shellmoulding, a first layer of fine sand-resin mix is formed adjacent the pattern-surface, and then a coarser mix is deposited on the partially-cured layer of the fine-mix. For the carrying out of this process, dump-boxes comprising two compartments, one containing fine-mix and the other a coarse-mix, may be substituted for the dump-boxes A, B. In one embodiment a dump-box C, Figs. 7 and 8, comprises an interior vertical wall 129 dividing the box into two compartments 154, 156, and a shaft 130 adjacent the upper-edge of said wall, rotatably supported in bearings 131, 132 and carrying a closure-plate 133 and a lever 136 having arms 137, 138. An external vertical-shaft 139 carries dogs 145, 146 and a bevel-gear 143 meshing with a bevel-gear 144 on the dump-boxsupporting shaft 114, which is rotatable in a bearing 115 and carries a sprocket 118 and windlass 147 by means of which a patternsupport and the dump-box and pattern-supportassembly may be rotated. The dog 145, during clockwise rotation of the dump-box to the inverted position, engages lever 137 to swing the closure-plate to engage stop 135, the plate being urged into engagement therewith by a spring. 151 when it passes the dead-centre position. Fine-mix from compartment 154 is then allowed to drop on to the pattern. The dump-box is then rotated in the same direction for one revolution to the same inverted position, the dog 146 engaging lever 138 to cause the closure-plate to engage stop 134 and allow coarse-mix from compartment 155 to fall on to the pattern. After formation of the shell, the windlass is turned counterclockwise to restore the box to upright-position and swing the pattern-support to open-position for curing of the shell and ejection of the mould. In a further modification. Fig. 10, the closure-plate 133 is actuated by engagement of a spring- loaded bifurcated member 160 with a stationary stop 163. The arrangement is such that, from the upright position, the box rotates through 180 degrees in one direction to deposit a finemix, 360 degrees in the opposite direction to deposit a coarser-mix, and then 180 degrees in the first direction to restore it to the uprightposition. In another modification, Fig. 21, the closure-plate is a slide-member 167, reciprocable between the end-walls of the dump-box in guides 168. The slide is connected to an operating-rod 172 linked to a spring-loaded member 176 having two arms 177, 178, and actuated by engagement of said arms with a stationary stop 183 on rotation of the box. In a further modification, Figs. 28-33, a generally cylindrical dump-box F is supported on an axially-extending shaft 189 rotatably held in bearings 190, 191. Pivoted on the box end-wall is a spring- loaded dog 198, and a similar dog 200 is pivoted on the stationary dump-box frame 202, both dogs being urged into engagement with a grooved-collar 194 keyed to the shaft 189. A generally H-sectioned mould-material support 205 is rigidly fixed to the shaft 189 in the box, defining compartments 211, 212. In operation, rotation of the box through 90 degrees in opposite directions, Figs. 30-33, from the position shown in Fig. 28, deposits fine-mix on to the pattern and causes the compartments to exchange positions relative to the box, so that by rotating the box through the same steps again, the coarse-mix is deposited and the compartments are restored to their original positions. The frictional-resistance of the charge prevents undesirable swinging of the material-support, but in a modification, Fig. 34, this result is achieved by dispersing the central-member 223 of the material-support 220 angularly, so that the weight of the charge urges the support in a clockwise direction against the resistance of the dog 200. Screens 242, Fig. 21, are preferably incorporated in each dump-box. Reference has been directed by the Comptroller to Specifications 725,470 and 726,739.