The following description will show a second method for making the cast roll. This arrangement produces clean and accurate castings, the machine-finish allowance being 3/8 inch. Fig. 376 illustrates the cheek flask a resting on and keyed to a cast-iron mold plate d. The open ring b on top of the flask is a stripping ring which holds the molding sand in place while the pattern c is being drawn. The pattern in this case has been drawn about 6 inches, the power being supplied by a crane. Fig. 377 is a section view of the arrangement shown in Fig. 376. The mold plate d should either be bolted to a sunken plate to hold it down while the pattern is drawn, or bedded in concrete as was done in the equipment here shown.
The pattern is a hollow casting with four arms cast at each end, and finished all over, and no draft is to be allowed. The pattern construction will be the same as suggested for the first method of making this roll, but without the steel shaft.
The mold-plate pattern is shown in Fig. 378. This illustration is upside down, and as only one casting is required, too much expense should not be put into its construction. The upper surface of the casting is to be finished and the recess for the dowel in the lower end of the pattern may be made by the machinist.
Fig. 379 illustrates the stripping ring b. A pattern for this part is to be furnished allowing finish on the underside and in the diameter of the hole. This ring should pass easily over the roll pattern, and, as soon as the pattern has been drawn, this ring is removed and the cheek is complete.
Fig. 377. Section of Cheek Mold on Mold Piste and Stripping Ring in Place.
Fig. 379. Stripping Ring.