It will be seen that the so-called “even-speed” smooth rolls run at approximately the same rate.
It is advised that in all cases the gear wheels should be cut helically. Those who have experience of the noise of some batteries after they are slightly worn will appreciate such a remark.
Grooving of Rolls.—Concerning the choice of grooving, there is divergence of opinion, some managers preferring one type, which others reject in favour of another type. Provided any particular type can be shown to be as effective as required, no necessity for laying down hard-and-fast rules seems to exist.
The following particulars serve to describe a battery well known to the writers, and accustomed to produce the finest quality of thin pale crepe and lower grades:
| Machine. | Grooving. | No. of Times Rubber passes through. | |||
| 1. | Macerator | Deep horizontal grooves; square-cut, 5⁄16 inch × 5⁄16 inch × 5⁄8 inch spaces | 3 | ||
| 2. | Intermediate | Horizontal grooves; 3⁄16 inch × 3⁄16 inch × 3⁄8 inch spaces | 2 | ||
| 3. | „ | Fine spiral grooves; 1⁄8 inch × 1⁄8 inch ×1⁄4 inch spaces | 2 | ||
| 4. | Geared smooth | Nil | 1 | ||
| 5. | “Even” smooth | „ | 1 | ||
| 6. | „ | „ | „ | 1 | |
| Total | 10 | times | |||
The actual rate of output of this installation is the capacity of the last smooth machine. This is about 180 lbs. per hour, while the output of the macerator is approximately double this amount. Thus the macerator only works for about half the time. This applies also to the two intermediate machines. After a study of the preliminary remarks, it would not be difficult to suggest methods for improving the condition of affairs. It would appear that, in order to obtain a uniform rate of working in such a battery, the relative peripheral speeds of the several machines should be—(1), (2), and (3) 100; (4) 150; (5) and (6) 200. The remarks on the practical limits of speed should be borne in mind. In this case the smooth rolls travelled at 23 revolutions per minute.
As already stated, it is not intended to lay down definitely that, e.g., horizontal grooving alone should be cut on macerating rolls. Some estates employ with satisfaction a deep square-cut spiral 1⁄4 inch by 1⁄4 inch by 1⁄4 inch or 1⁄2 inch spacing; others use a large diamond pattern. Similarly various types of grooving are cut in the intermediate rolls.
A Battery of Machines.