The lever is thrown to its extreme outward position. The pin of the shaft is now out of engagement with the driving pulley and the shaft is brought back so that its forward end is within the collar of the pulley and the slot on the shaft is in a position permitting the paper to be easily inserted. The position of this slot is defined by the pin on the shaft, following the guide on the rear bearing, so that it is always in the same position. The first operation is to move the lever forward and to thread the paper into the slot, as shown in figure 6.
Fig. 6. - Case-rolling machine; feeding paper in slot.
The forward movement of the shaft continues until the paper is inserted in the slot of the shaft with the pasting notch protruding beyond the edge of the paper, and the forward end of the shaft resting on the forward bearing. In this position the pin on the shaft is engaged by the lug on the pulley and rolling commences.
Fig. 7. - Case-rolling machine; paper rolled on mandrel.
Fig. 8. - Case-rolling machine showing final operation.
Figure 7 shows the machine in the position for rolling the case, and the counterweight on the lever is shown at dead center. When all the paper is wound upon the shaft the operator, with one hand encircling the revolving case, binds the outer laminations by a slight pressure, at the same time evening up the edges and smoothing down the outer feathered edge.
This operation is shown in figure 8. The completely rolled case is removed from the machine by the simple operation of throwing the lever to its rear position, the shaft receding from the case and forcing the feathered edge of the paper, held in the slot, to follow the pasting notch and to be pasted against the inner walls of the case. This latter operation is shown in figure 9.
Fig. 9. - Case-rolling machine; removing case from machine.
It is essential that a good paste be used. The following formula is one which manufacturers favor: A good grade of Hecker's rye flour, 124 pounds, and granulated alum, 5 pounds.
The alum is first dissolved in twenty gallons of cold water, then the flour is added and thoroughly mixed, more water being added so as to bring the slurry to the proper consistency, the total amount of water being approximately 120 gallons. This should make a thick paste. The mixing of the flour, alum, and water is accomplished in a machine shown in figure 10.
Fig. 10. - Paste-mixing machine.
This machine has the capacity of one charge and is provided with blades which revolve and act as cutters and agitators. The machine is essentially a bread-mixer. Live steam is introduced into the slurry and the latter is cooked for about 10 minutes. The manufacturers claim that the use of alum is essential, as it acts as a preservative to the paste.
The bottom heading consists of a high-grade molding clay which is pressed into the bottom of the case by a hydraulic press. The charge of clay varies from 1 1/4 to 2 1/2 ounces, depending on the quality, and is pressed to a thickness of 3/4 of an inch. A tapered orifice is cored in the center of the clay heading by means of a spindle.
Fig. 11. - Placing cases on spindles.
Fig. 11 shows the operation of placing the cases on the spindles which are attached to a metal table resting on the circular platform of the hydraulic press. Six cases are loaded at the same time in this manner. A guide block is now placed in position on top of the cases, holding them firmly. This guide block is shown in figure 12, as is also the method of introducing the clay into the case.
A rack holding three small measuring cups, having an inside diameter of 1 1/8 inches and a depth of 1 1/4 inches, is used for measuring and introducing two separate charges of clay.
Figure 13 shows the rammers set in position for pressing. On the top of the machine, as shown in the figure, are extra rammers, which are in reality hollow steel tubes with the inside diameter large enough to pass freely down the spindle. A brass bushing approximately 1 inch long is inserted in the bottom of each rammer to prevent the striking of a spark by a steel-to-steel contact should the rammer strike against the spindle.
Fig. 12. - Introducing clay into cases.
Fig. 13. - Plungers.