(410) Having covered the rollers they are subjected to a rolling pressure, so as to render them perfectly cylindrical. The machine shown in Fig. [220] is a special one of Messrs. Dronsfield Brothers, and consists of a steam chest to which steam is admitted. The upper side of the chest is planed so as to be quite true, and upon it the rollers are placed. Above the steam chest a table or plate A is imposed, having a reciprocal motion to and fro over the steam chest, derived from the cranks N. Four rollers are fed at one time, and after being subjected to the action of the pressure plate during four of its double movements, are delivered at the other end of the machine. Owing to the heat of the surface on which they are rolled, and the peculiar movement given to them, the rollers emerge in a truly cylindrical form. Ten rollers can be thus rolled per minute, and no difficulty is experienced in attending to the machine. It is, of course, essential that there should be no unevenness of the rollers, and the treatment accorded them by the series of machines described ensures this being avoided.
Fig. 220.
(411) It is sometimes the practice to grind the leather covered rollers so as to remove any flats formed during working. Messrs. John Hetherington and Sons make a machine for this purpose. By it the rollers, while held in suitable bearings, are subjected to the action of a revolving grinding disc, covered with glass paper, which traverses the whole surface of the roller and grinds it up perfectly true. The rollers so produced are quite cylindrical, and a large number of the machines are in use.
(412) The bobbins which are used in the various machines employed are made of specially selected timber, which is kept in stock until it is thoroughly well seasoned. The bobbins are carefully turned, and are smoothly finished on their surface, so that the cotton does not adhere to them when it is wound upon them. Their shape and general construction is well shown in Fig. [221]. In this A B and C represent various types of roving bobbins, spools, or “tubes,” these being drawn from samples supplied by Messrs. Wilson Brothers, Limited. The tubes are shown of three designs. The one shown at A is single ended—that is, can only be used one end up. In the foot of the tube—which is enlarged—four notches are cut which engage with the projections on the top of the driving bevel pinion described in Chapter [X]., by means of which it is positively driven. A similar construction is shown in C, but this is a shorter tube, suitable for a roving frame, where the lift is less than that of the slubbing frame. B is double ended, and can be used either end up, as desired. It will be noticed that all these tubes are shelled out internally, so as to be very light, and they are so constructed at the top that they fit easily upon the spindle or collar. In this way, while they are steadily held, they can slide without undue friction, which is a somewhat important point. The bosses of the tubes, as shown, are hooped with metal rings or shields. The object of this is to protect them from damage when, after doffing, they are placed upon the spindles, this operation being often very roughly carried out. The tubes are, as stated in Chapters [X]. and [XI]., placed in the creels of the roving frames, mule and ring frames, on “skewers,” the construction of which is shown at D and E. These are made of ash usually, and are finely pointed, so as to revolve easily and freely.
Fig. 222.
Fig. 221.
(413) Bobbins for ring frames are made as shown in F, G and H (Fig. [222]). The forms illustrated in F and G are intended for use with Rabbeth spindles, and that marked G is hooped at its lower end for the reasons indicated in the previous paragraph. The bobbin or spool H is used for spinning weft on ring frames, and is much smaller than the type employed for twist yarn. It is a common practice to fit shields to all kinds of bobbins, several makers doing so in one form or another. A special form of ring bobbin is made by Messrs. Wilson Brothers, of Barnsley, in which the grip at the foot is entirely done away with. The bobbin is a double flanged one, something like the type shown by the letter I, but has a projecting lower boss or nipple which loosely fits the spindle cup. This is the invention of Mr. W. R. Sidebottom, of Stockport, and at the time of writing it is undergoing an extensive trial. So far as this has gone the results are favourable, and no loss of twist has been detected although the grip contact does not exist. The bobbin shown by the letter I (Fig. [223]), is the form employed for doubling purposes on ring frames, and is driven by the slot shown in the detached plan view. The bobbin L is the form used on throstle spinning frames, as adapted for long collars, somewhat resembling in principle the Mason collar described in Chapter [X].