Quills for Shuttles
The making of proper quills for use in the shuttle is of no small importance, for on this the evenness and uniformity of the selvage very much depends. When flanged wood quills are used, the guides should be carefully adjusted so that the filling is uniformly spread over the entire length of the quill, allowing for perfect freedom at each end without dragging. Quills should not be overloaded. In drum pressure quilling, the automatic stop should be so arranged that the quill will be filled even with the outer edge of the flanges and no more.
Should there be any tendency to hardness in the material used for filling, it may be found advisable to run the thread over a plush pad on which has been applied a light application of cocoanut oil, but great care should be exercised not to overdo this as there is nothing so hurtful to rubber goods as oil.
The quills should only be of sufficient length to allow for uniform delivery from the shuttle without dragging at the ends. To assist in this elongated shuttle eyes are preferable to round ones, so as to shorten the angle at which the filling leaves the quill when running from the extreme end. Thumb bits should be so adjusted that the delivery is uniform from start to finish. The quill flanges should not lie flat against the sides of the quill opening, but should be pointed at the ends so as to reduce the friction. Quill wires should be of hard tempered steel and be perfectly straight at all times. When it becomes necessary to run narrow goods in wide spaces, recoil springs should be provided to gather up the loose filling.
Care Required in Finishing
The finishing of elastic fabrics is a process which demands great care, and has to be taken into calculation from the beginning of the web construction. Calculations must always be made as to what effect heat, moisture and sizing will have upon the covered up elastic threads, confined as they are in a multiple of small cavities and under high tension. As soon as the softening influence of heat and steam operate upon the covering of cotton yarn which confines these threads, the rubber strands begin to assert themselves and contraction at once takes place. To what extent this can go must be predetermined in fixing values, and a certain degree of uniformity of contraction arranged for.
Webs which are perfectly flat and straight when taken from the looms are liable to be transformed into unshapely products and completely ruined by unsuitable finishing. For instance, take a web with a twill center and a plain border which is apparently flat and satisfactory at the loom. The effect of heat and steam upon such a web will be to contract the soft woven center more than the harder woven plain border, which will cause the web to be long-sided and curl. Such a condition must be anticipated in the construction of the web and provision made to offset its occurrence. Sometimes it must be met by a change in the size of some of the yarns used, or number of threads employed at given points, or perhaps added gut threads must be introduced to stop contraction in certain places. It must always be remembered that we are dealing with a very much alive element when we are finishing rubber goods, and that unexpected results may at any time arise.
Finishing Machines
Finishing machines vary both in design and capacity, but the general principle is the same in all. A series of drying cans are arranged for the application of the sizing mixture. Some machines are laid out horizontally and some are upright. In the longitudinal layout the machines are more easily accessible in their different parts and under better control, while the upright machines are more compact and occupy less floor space. Fig. 3 shows a horizontal machine of the latest type. It has a drying capacity of eleven cylinders, 24 inches wide, 36 inches in diameter, allowing for a web contact of about 100 feet. These cylinders are arranged in two decks so as to economize in floor space.