Such castings as short lengths of pipe, and elbow and T-pipe fittings of reasonable diameter lend themselves readily to this method of molding. It would not be economy to equip for this method if a very few castings are required, or where the requirements would suggest the costly equipment for casting pipes on end. Like other methods of molding, it has its scope, and the pattern maker should not attempt to design an equipment for this work without first consulting with the master molder.
The casting considered will be a short length of cast-iron pipe, 72 inches long, 6 inches inside diameter, and flanged at one end. The construction of the pattern will not be considered, as it is a parted pattern with a detachable flange similar to that considered before. In fact there is no difference in the pattern used with a dry-sand or with a green-sand core.
Fig. 363 illustrates the iron core box, the halves being hinged together as shown at a. The arbor, Fig. 371, is placed in the drag half, the ends extending through the notched ends of the core box. Green sand is rammed in drag and cope and struck off level with the top of each half. The core box is closed by lifting on all four handles like closing a book, print upward, then rolling over into position shown in Fig. 364. The upper half of the core box can now be returned to its first position, leaving the cope half of the core resting on the drag itself. The complete core can then be drawn from the core box - lifting it by the arbor extensions - and placed directly in the mold. The flask end3 should be notched to receive the arbor extensions, as illustrated in Fig. 365.
Several methods of constructing the master pattern for the core box may be utilized. As only two castings are required - one for each half of the core box - the quickest method of constructing the pattern should be used, provided the results are accurate. A nailed and glued pattern using a green-sand core for molding the inside would produce the smoothest casting, Fig. 366. The pattern, however, would be very fragile, and a form should be made to fit the inside to hold it in shape while ramming the drag mold.
Fig. 368. Wooden Form.
The construction considered will be to furnish the molder with separate flanges and lagging, and assemble the parts on a wooden form, Fig. 367, or a dry-sand core can often be used in place of the wooden form.
The form, Fig. 368, is constructed of thin strips of wood nailed to several semicircular heads shown at A; the length to be the inside length of the core box. The strips of lagging should be about 3/8 inch thick; the edges need not be fitted together, but the diameter must be of the dimension required. The pieces h should be made 1/8 inch over the half circle; that is, the center of the circle is 1/8 inch in from the edge, as shown at i in Fig. 369. This 1/8 inch is for a metal finish allowance on the face of each half, as the core box must close accurately its entire length. Part b is the end flange, and c is a lug, shown in Figs. 367 and 369. The space between b and c is wide enough to allow the part d to turn easily. This form of hinge, having a double shear to the steel pin a, is very strong and much better than if only one lug were used on each half of the core box. The part e is the transverse flange, while f and d form the end of the cope half. Lagging is to be provided which should be about 1/4 inch thick and 1/2 inch wide. This is shown in Fig. 367 at k, and the part g, Figs. 365 and 367, is nailed to one of these strips of lagging, as shown in Fig. 369.
Fig. 369. Ends, Flanges, and Hinge Lugs.
Fig. 367 illustrates the several parts of the pattern assembled on what is called a false cope. This cope flask is rammed and struck off level with the joint; the form j is placed in position; the flanges l and the lagging k are laid upon this form. The ends b and the lugs c are located, and that part m of the hinge lugs is bedded into the false cope, Fig. 367. The drag mold can now be rammed and turned over, the false cope removed and the form j removed. The cope mold is now made and the pattern can be drawn.
Fig. 370. Core Box for Cast-iron Handle.
If it should be desired to mold the inside of the core-box casting with a dry-sand core, the form j may be omitted and the pattern parts assembled directly on this core.
Handles should be cast on each half of the box, as illustrated in Figs. 364 and 365. These handles are molded in a dry-sand core and rammed in the mold, as shown at n in Fig. 367. The core box for this handle is illustrated in Fig. 370. The length of the handle should be about 4 1/2 inches, the diameter about 1 3/9 inches, and the diameter of the hole 7/8 inch. Allow about 1 inch of core sand on each side of the handle pattern and a draft of fully 1/2 inch on each side. The height or depth will be 5 1/2 inches for a handle of these dimensions, making the top end of the core print flush with the top of the core box. A cylindrical stock core 7/8 inch in diameter is pasted into this core, so as to cast a hollow handle. Arbor. The skeleton frame used for reinforcing the drag half of the core is an iron casting. This is illustrated in Fig. 371. The pattern consists of a rectangular arbor r and of several patterns for the flanges s. These flanges should be notched to fit over the arbor, but need not be attached in any other way, the molder placing them in the position required; bis judgment of the spacing would naturally be better than the pattern maker's. The end flanges should be placed at the extreme end of the core. The outside diameter o would be about 3/4 inch less than the outside diameter of the core, and the thickness about 1/4 inch. The outside circular edges should be chamfered to a thin edge, so as to prevent soft ramming under the flanges. The width q should be 1/4 inch less than the half circle, as it is required to have the sand rammed over the top of the arbor. The arbor extensions at each end, however, shall be constructed to the center, so that the cope flask will rest upon these ends, preventing the arbor and core from lifting when the mold is poured.