(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.

(47) In Fig. 10 is illustrated, also in longitudinal elevation, a machine made by Messrs. Dobson and Barlow. The cotton is fed by a lattice L, as in the preceding example, the course of which is clearly shown. In this case the machine is fitted with pedal levers V, these being employed to regulate the feed. This motion and its method of action will be described at length in the next chapter. It suffices to say that the cotton on issuing from the feed roller is struck by teeth or projections on the surface of the cylinder O which revolves from left to right. Surrounding the latter is a semi-circular grid K with conical teeth, which encircles the cylinder for more than half its circumference, through which the dirt is thrown, the cotton being cleaned by these means. It will be noticed that in this machine the area of the circular grid K is large, and that the material at once passes upon it after it is struck by the cylinder. As soon as the cotton leaves the surface of K it is carried forward over the grid U, placed in a position well calculated to allow of the easy movement of the material, and by means of which the removal of the dirt and sand is more easily effected. The grid U is also made of considerable area, so as to afford a large cleaning surface, which is a desideratum in this class of machine. After leaving U the cotton is collected on the cages D, and subsequently passed through the scutching machine, which in this case is combined with the opener. As this machine is used as a separate one, it will be better to leave its description until it is dealt with by itself. It is only necessary to say that it will be shown by numerous examples that the whole of the cleaning machines are often combined in various ways, which are arranged to suit the special circumstances of any case. These are so different that the combinations are widely diverse.

(48) The Porcupine opener is so named from the employment of a cylinder or beater consisting of a number of teeth spikes or blades. Two forms of the beater, as made by Messrs. Lord Brothers, are shown respectively in Figs. 11 and 12. The form shown in Fig. 11 is intended for use in cleaning long-stapled cotton, and consists of a number of discs secured to a central shaft. To these steel blades are bolted, which are so shaped that they can be reversed when worn. The beater illustrated in Fig. 12 is formed of a number of cast-iron discs, each of which is hollowed on one side, and has a projecting flange or boss on the other. These are turned to fit one another, and are bolted together by long screws. They are further bound by a nut fitting on a screwed part at one end of the shaft, by which they are pressed against a collar at the other end. The teeth are V shaped and are chilled, being readily sharpened after wear. In the event of the teeth of one of the discs being broken, it is only necessary to remove it by breaking it up. An additional disc can then be put on the end of the shaft, and the whole screwed up again as at first. In this way the whole of the advantages of a solid roller are secured, with much greater facilities for repair.

(49) However the cylinder is constructed it is sustained by bearings secured to the framing of the machine. Beneath it a grating or grid is fixed, similar in construction to those previously described. The bars are in all cases shaped so as to present a sharp angle to the cotton as it is thrown forward by the cylinder. A dirt chamber is, as usual, formed below the grid. The cotton is fed by a lattice and feed rollers. The latter are formed in the ordinary way, with a number of circumferential V grooves, crossed by a series of similar longitudinal grooves, so as to form a large number of teeth, which securely hold the material as it is fed. As the cylinder revolves 1,000 times per minute, the teeth strike the cotton and disentangle the fibres, throwing them with considerable force against the grid.

(50) Although the Porcupine opener can be used separately and the cotton discharged into the room, it is more usually employed in connection with some other type of opener, or with a scutching machine. Formerly it was a common practice to use this machine separately, in which case it was fitted with two cylinders one behind the other. Now it is mostly employed as a feeder to another machine, and the combination gives very effective cleaning.

(51) Such an arrangement is shown in Fig. 13, which is a special one of Messrs. Platt Bros. and Co. The lattice feed F is placed alongside the mixing bins, and is provided with a large collecting roller, behind which are a series of pedals, described in the next chapter, and two pairs of breaker cylinders. By these the cotton is fed regularly and broken up into small pieces, or partially opened before being passed forward to the opener cylinder. The Porcupine feed rollers G deliver the cotton, in the case illustrated, into the air tubes D, and thence over a patent dust trunk K, where much of the dirt is deposited, and which is afterwards described.

(52) The opener, as made by Messrs. Platt Brothers and Co., Limited, is shown in perspective in Fig. 14. The cotton enters the opener chamber by the tube, as described, and is at once acted on by the cylinder, which revolves horizontally. The cylinder is surrounded by grids, against which the cotton is thrown, and through which the dirt is ejected. The forward movement of the cotton is induced by the exhaustion of the air, produced by means of a pair of fans, placed one at each side of the machine and adjoining the exit orifice from the cylinder chamber. Power of lateral adjustment is given to these fans, so that they may be set in towards the centre of the machine to a greater or less extent. In this way the stream of cotton, as it issues from the cylinder, is directed on to the cages as required, and a very even lap or sheet is thus obtained. It is obvious that the guiding power of the air current is the right thing to rely upon, and, by the arrangement described, ample regulation of it is obtained. A lap which is even in thickness is absolutely essential to good work, and the arrangement of fans in the way described ensures this being obtained. The author recently saw the first lap made on a machine of this type in a large Oldham spinning mill, and the regularity of the thickness and evenness of the selvedge was very noticeable. The machine as shown in Fig. 14 is a combined one.

(53) The Crighton Opener is a machine the distinctive feature of which is the employment of a vertical conical beater. A sectional elevation of the machine as made by Messrs. Crighton and Sons is shown in Fig. 15. The beater consists of a number of cast-iron discs D securely keyed upon a vertical shaft, which is sustained at its lower end by a bearing E in the frame F, and at its upper end by the bearing A. On the discs are fastened steel blades, and it will be noticed that their diameter increases from 18in. to 33in. Surrounding the beater is a casing B, in which are a number of longitudinal slots, the inner surface of the grids being in most cases made of the shape shown in section in Fig. 16. A recent improvement by Messrs. Crighton and Sons is shown in Figs. 17, 18, and 19.

(54) The cotton is fed by the tube placed at C, and a fan is fixed just below the entrance of the tube into the beater chamber. The direction in which the cotton enters and the positions of the fans are important points of construction. The feed tube is not fixed in a straight line, but is slightly curved so as to direct the cotton upward as it enters the beater chamber. As it enters it comes in contact with the serrated surface of a truncated conical dish, within which the lowest arm D of the beater revolves. Immediately below this dish a fan disc of the Schiele type is fixed in machines in which a combination of feed table, air trunks, and opener is made. The object of this fan is to exhaust the air in the tubes up to that point, and draw the cotton forward until it reaches the cylinder. There is a decided advantage in this arrangement over one in which the fan is placed beyond the exit orifice at the top of the opener chamber. In the latter case the air is required to draw the cotton through the dust trunks into the opener, upwards past the cylinder, and so on to the cages. In the machine as made by Messrs. Crighton, the fan at the bottom of the dish is sufficient to bring the cotton to that point, and all that is subsequently required of the fans placed beyond the cylinder is to lift the cotton upwards during its progress through the beater chamber. On this account a slower moving current of air can be employed, and the fans connected with the cages can be revolved at a less velocity. The full advantages of this arrangement will be afterwards pointed out, but as the cotton is raised slowly while being beaten, it is thoroughly opened and cleaned.

(55) When the cotton enters the beater chamber it is at once struck by the blades of the beater, which revolve at a speed of about 1,000 turns per minute. The peripheral velocity of the blades is thus at the bottom 4,712 feet per minute, and at the top 8,639 feet. The blow thus given disentangles the cotton and flings it against the inner surface of the grid, thus momentarily arresting its motion. As the beater revolves, the cotton continues to find its way upwards, and in its course is repeatedly struck by the blades, which, as has been seen, have a continually increasing peripheral velocity as they near the top. In this way, as the cotton nears the exit orifice, which is placed at the upper part of the machine frame, on the opposite side to the tube C, it is thoroughly beaten into a fleecy condition, with its fibres well disentangled.

(56) The shape of the grids surrounding the cylinder is an important matter. In the form illustrated in Fig. 16, the projections on the grid are triangular in shape, and have slots between each pair through which the dirt can freely pass. It will be easily seen that the shape of these grids is one which will only exercise a little clinging effect upon the cotton, which, as it is impelled by the stroke of the beating blade, will very readily roll pass the projections. As the rapid rotation of the cylinder tends to slightly compress the air, the latter finds an outlet if possible. This is the object of the slots in the grid casing, and they fulfil it very well. But there is always a liability that along with the air and dirt—which also passes the grids—a little fibre may escape. It is desirable to avoid “fat droppings” as they are called, and the grid shown in Figs. 17 to 19 has been designed for this purpose. Each of the pockets C Fig. 18 shown becomes a resting place for the opened fibre, and as its lower end C² is open, the dirt can fall freely. In order that the air can easily get away, between each pair of pockets a small slot is formed, and in this way there is no downward impulse given to the cotton while held in the pocket. Thus each blow given to the material opens it, drives it into the pockets where it dwells for a short time, and from which after the passage of the beater blade A, it is drawn by the suction of the air. By this system there are given short periods of rest, which very materially facilitate the fall of the dirt.

(57) Instead of feeding the opener manually as shown in Fig. 15, a lattice feed can be adopted. Among the many important points in connection with the Crighton, or, as it is sometimes called, the “exhaust” opener, none is more so than the construction and lubrication of the footstep. This is arranged so that the foot of the beater shaft revolves in a constant bath, either of oil or water, and great care is taken to cover it so as to prevent the entrance of sediment or dust.

(58) In Fig. 20, a longitudinal section of the machine as made by Messrs. Lord Bros., is given, and is accompanied by a plan of the same machine as combined with a porcupine feed. Referring first to the plan, the lattice feed A delivers the cotton to the porcupine roller C, by which it is passed in a partially opened condition to the air trunks D. By these it is conducted to the opening chamber F, being admitted to it by flap valves G. The cotton enters the chamber F by the tube H, terminating in the dish I. The exit orifice is placed at the top of the chamber F, the course of the cotton being shown by the arrows. The cylinder is similar to the Crighton, but the blades E are fixed in malleable iron arms L fastened to the shaft, and can, after wear, be reversed. Below the foot of the shaft, and within the bearing O, is a loose washer P, which can rotate with the pressure of the shaft, this arrangement considerably lessening the wear. At each side of the exit of the delivery tube, fans N are fixed, which, like those in the Platt machine, can be adjusted sideways for the same object. The cotton then passes over grids R on to the cages T, from whence it passes through the scutching beater W to another pair of cages S, as indicated by the arrows, and is finally formed into a lap as shown. The special construction of the beaters enables the cotton to pass freely upwards, and prevents any stringing occurring. The speed of the beater in this machine is 520 revolutions per minute for American cotton, and 720 for Indian. The slower velocities used necessarily imply the use of less power.

(59) There are one or two points to be noticed in concluding the consideration of the Crighton type of machine. The distance from the face of the grids to the ends of the beater blades should be carefully arranged to suit the class of cotton treated, as, if it is too great, the opening is not properly effected, and, if too little, the cotton is liable to be damaged. The rate at which the feed is conducted should always be carefully watched, because, if the material is passed in too quickly, its bulk becomes so great in the lower part that the dirt cannot fall freely, but is received by the entering cotton. Cleaning is not, therefore, so effectually carried out. In addition to this, it is desirable that the cotton should be allowed to assume a perfectly open condition, which it would do with difficulty if the space were overfilled. Cotton has been passed through, for a short time, at the rate of 110,000lbs. per week of 60 hours, but for the reasons stated, 30,000lbs. is ample.

(60) It might be thought that the pitch of the projections on the inner surface of the grid should be as small as possible, but this is a mistake. It is essential that the cotton should strike not merely the top or apex, but one face or side of the projection, if the full cleaning effect is to be obtained. It is obvious that if the pitch is too fine no such face blow would be given, and very inefficient purification would occur. The considerations thus stated are founded on actual experience in working the machines, and should be borne in mind in constructing or controlling an opener of this type.

(61) It is considered by some makers to be advisable when using this style of machine to employ one with two beaters revolving in separate chambers, connected to each other by an air pipe. This is more especially the case when Indian or short stapled cotton is used. When the double machine is used, the conducting tube between the two leaves the first chamber at the top, and enters the second at the bottom. The driving of the opening machine is usually obtained from a counter shaft, by which means the speed of the driving pulley becomes a moderate one.

(62) A machine, of which large numbers have been made by Messrs. Lord Brothers and Howard and Bullough, has a conical beater placed in a horizontal position, and the opener proper is usually combined with a scutching and lap machine. As this type of machine is very similar in its general principles to that previously described, and is not now so largely made as formerly, it is not necessary to give a detailed description of its mechanism.

(63) It has been repeatedly stated that the various machines are united by means of tubes, so that the cotton can readily be taken from one machine to another. It does not matter whether the machines are in the same room or not, or what distances separate the rooms in which they are placed. This has been shown in Figs. 6, 7, and 8, referred to in the preceding chapter, and the further arrangement is illustrated in Fig. 13. In this case the cotton, after being delivered into the dust trunk, or tube D, on its way to the opening cylinder, may be carried two or three hundred yards, if desired, before it reaches the latter. There is, of course, a limit to the distance it may be conveyed, but it is a very wide one. There are many conveniences arising from this procedure. It is becoming a very common practice to build the mixing and scutching rooms away from the main body of the mill in order to minimise the risk of fire. But even where this practice does not obtain, the employment of air tubes is a good one, as it enables the material to be transferred from one point to another without handling. In this way the cost of labour is much reduced, and in addition the cotton is less liable to damage.

(64) At one portion K of the conducting tube D an arrangement is fitted by which a partial cleansing of the cotton occurs before it reaches the opener. Below the level of the tube a chamber nearly square in section is formed, as shown in section at the left-hand corner in Fig. 20, forming the tube into a D shape. This chamber is made of a length which is determined by the character of the material used and considerations of its position, etc. At intervals of a few inches plates are arranged so as to divide the chamber into a number of compartments, as shown by the sectional view. Over the top of these plates the material rolls in its forward movement, and a large quantity of dust, sand, and heavy impurities are deposited in the trunk. Doors are fitted to the underside of the chamber, by which the droppings can be removed at intervals as desired. The use of these grids has been attended with unmistakeable benefit, and leads to a much more effective cleaning of the cotton.

(65) By the method just described it is necessary to cleanse the trunks manually at intervals, and if any neglect occurs there is some danger of the dirt being carried forward. To obviate this, Messrs. Platt Bros. and Co. Limited have patented and applied the arrangement shown in Fig. 21. In this case the dust chamber L is sustained in a manner arranged to suit the circumstances of the case. Instead of being fitted with the vertical plates described, an endless band is carried over two drums, one at each end of the chamber. This band K is driven from the pulley shown by means of worm gear, and receives a traverse at its top side in the reverse direction to the air current. On the band are fitted a number of blades or teeth, between which the dust or dirt can fall. The traverse of the lattice carries the dirt forward, and when the teeth are turned downward it falls into the spout or receptacle N, and on to the top of an iron flap P, usually kept in a horizontal position by the balanced lever fitted on the spindle on which the flap oscillates. The collection of a sufficient quantity of dirt destroys the equilibrium and causes the flap to tip, allowing the dirt to fall into a sack suspended below the orifice to receive it. In the event of any dirt falling on to the bottom of the chamber, two or three special blades are arranged to scrape along it and draw the dirt to the other down spout O, where a similar action occurs. This arrangement has two advantages. It constantly presents to the advance of the cotton new and clean receptacles for the dirt, and it automatically removes the latter from the path of the material. These are decided improvements, and the arrangement is a considerable advance on its predecessor.