Modern Cotton Spinning Machinery, Its Principles and Construction

by Joseph Nasmith

CHAPTER IV.
THE OPENING MACHINE.

(39) Mixing being completed, the cotton is treated by machines specially designed to remove the impurities which are always mixed with it as received from the shipper. These impurities include sand, dirt, broken seed, and leaf. In addition to these there is a certain quantity of “nep” which is caused, as previously described, by the matting together of short, unripe, or immature fibres. To eliminate the whole of these substances, two sets of machines are required; the first being responsible for the removal of the heavier foreign bodies, such as sand and dirt, and the second for that of leaf, nep, and short fibres.

(40) Of the machines in the first division the opening machine, or more briefly the “opener,” is the first. Its raison d’être is found in the matted condition of the cotton as taken from the bale, and the less open it is when taken from the stack, the greater the work of the machine. As the name indicates, the object of the latter is to disentangle the fibres, but it is also designed to remove many of the impurities held by the cotton. This twofold aim is the one with which all the series of cleaning machines are constructed.

(41) The method invariably pursued in opening is to beat the cotton by subjecting it to the blows of arms revolving with considerable velocity. It may aid in the understanding of the process, if a few words are said as to the primitive method of cleaning. Formerly the material was laid upon grids in small quantities, and was submitted to repeated light blows of rods or sticks delivered manually. In this way the mass was gradually beaten into a fleecy condition, and the dirt held by it dropped through the interstices of the grid. In some respects, this treatment has never been equalled, but it is, of necessity, very slow, and could not be commercially employed at the present day. At the same time, it affords a clear indication of the needs of the case, and is a guide to the proper treatment.

(42) In dealing with the fibre by revolving beaters of any kind, two things are essential to success. First, the blow given must be of such a character that the fibres are completely separated, while any rupture or breakage of them is avoided. Second, the surface against which the cotton is flung after being struck by the beater, must be arranged to permit of the free passage of all impurities, while, at the same time, so arresting the movement of the tufts or pieces of cotton as to shake out the extraneous substances.

(43) The direction in which the cotton enters the machine, the diameter, construction, and shape of the beater arm, and the speed of the beater, are three of the essential features of a machine of this kind. The successful removal of the impurities depends on the rate of the feed—that is, the amount of material passed into the machine in a given time—the shape of the projections on the casing surrounding the beater, and the distance of these from each other; in other words, their pitch. It is not a difficult matter to effectually cleanse the cotton, so long as regard is not paid to the loss arising from damaged or broken fibres, or from the amount of fibre driven out with the dirt. It is, however, always to be remembered that it is desirable in any process to utilise every portion of the material which is capable of being worked up, and herein lies the chief difficulty of the subject. In brief, the essential consideration is a commercial one, and that machine is the best, and is used most skilfully, which effectually opens the matted cotton and shakes out the largest body of impurities with the least loss of fibre, either from its being driven out with the dirt or by breakage or rupture. Economy and efficiency are the watchwords of a good spinner, and nowhere is this combination more desirable than in the early stages of the manufacture.

(44) There are three principal forms of machine used for the purpose of opening—the Oldham Willow, the Porcupine, and the Crighton Opener. The former is now employed rarely for cotton, but extensively for the manufacture of yarn from waste. The other two are often employed, but the Crighton type of machine is perhaps more widely used than any other. There is another type of machine, which is also in extensive employment, to which reference should be made, viz., a modified opener, on the Willow model, of which a description will be given.

(45) The Willow is constructed with a revolving cylinder, about forty inches wide and the same diameter, fixed on a shaft borne by suitable pedestals. It is provided with several rows of blunt teeth on its periphery. Above the cylinder a semi-circular casing is fixed, which is provided with similar projections to those of the cylinder. Below the latter a grating, grid, or “undercasing,” formed of a number of parallel bars, is placed. The cotton is flung against these bars, and the loosened dirt falls through the spaces between them, being drawn away by an exhaust fan and delivered outside the room. It is the usual practice to feed the machine by an endless lattice, or apron, of a similar construction to that previously described. When the cotton enters the machine it is struck by the teeth on the cylinder and thrown forcibly against the projections on the casing. The blow thus given, combined with the periodical arrest of its motion, causes the cotton to be thoroughly opened and shaken, the dirt falling downwards and being drawn away by the air current. As has been said, the Willow is falling into disfavour. The cotton is subjected to too severe punishment, and is therefore damaged. In addition to this, it is sometimes carried round several times, and is formed into a sort of rope, which renders its subsequent treatment more difficult. Moreover, the waste is greater than is desirable, and, generally speaking, the use of this machine for cotton is of doubtful utility.

(46) In Fig. [9] a longitudinal section of an opener, which in some respects is a modified type of Willow, is illustrated. This machine is made by Messrs. Taylor, Lang and Co., Limited. It consists of a feed lattice Q, which travels in the direction of the arrow, and delivers the cotton to the pair of feed rollers shown. These are duplicated when no regulating apparatus is used, and are three inches in diameter. The cotton is delivered at any desired speed by the rollers, and as it projects from them is struck by the spikes or teeth on the cylinder O, which revolves in the direction shown by the arrow. Surrounding the cylinder is a case P, the inner surface of which has a number of projecting nogs formed on it, against which the cotton is flung with considerable force. This shakes out the dirt to a great extent, and opens the material. After passing the casing P the cotton is taken over a circular grid surrounding one side of the cylinder, and contained in the body of the machine. This grid is formed of a number of steel bars, between each pair of which an opening is left. Thus as the disentangled cotton passes over it the heavy dirt falls out through the openings into a space left for the purpose. After passing the grid the material leaves the cylinder by the passage shown, immediately on entering which it travels over the top of fixed grids R, through which the sand and similar material can fall. After this the cotton is either delivered into the room or is carried forward to a pair of “cages” S, through which a current of air is drawn. This part of the machine will be described in the next chapter, and it is only necessary to say that the fleece of cotton is formed into a sheet and rolled up as shown at L, into a “lap.” If the cotton is delivered loose it is thrown on to a second lattice, by which the delivery is made. In order to secure a regulation of the air current the louvre openings I are provided. The area of the cleansing surface in this machine is great, and 50,000lbs. of cotton can be cleaned in a week of 60 hours unless a “lap” is formed, when the quantitity is reduced to 28,000lbs.