The drawing and doubling

are the next operation. The ends, as they come from the cards, are exceedingly tender and loose, but the filaments of the cotton are not as yet laid so parallel with each other as they need to be for machine spinning. Before any degree of torsion therefore be communicated, a previous proce is required to give the filaments a level arrangement in the ribands. The drawing out and doubling accomplish this purpose, and in a manner equally simple and certain. The means employed are drawing-rollers, whose construction must here be fully explained, as it is employed in all the following machines; one example of their use occurred, indeed, in treating of the cards. IMG:4147767755307473660_illo0351b.png:Drawing out mechanism Let a and b , fig. 328. , represent the section of two rollers lying over each other, which touch with a regulated pre ure, and turn in contact upon their axes, in the direction shown by the arrows. These rollers will lay hold of the fleecy riband presented to them at a , draw it through between them, and deliver it quite unchanged. The length of the piece pa ed through in a given time will be equal to the space which a point upon the circumference of the roller would have per cured in the same time; that is, equal to the periphery of one of the rollers multiplied by the number of its entire revolutions. The same thing holds with regard to the transmi ion of the riband through between a second pair of rollers, c , d , and a third, e , f . Thus the said riband i ues from the third pair exactly the same as it entered at a , provided the surface speed of all the rollers be the same. But if the surface speed of c and d be greater than that of a and b , then the first-named pair will deliver a greater length of riband than the last receives and transmits to it. The consequence can be nothing else in these circumstances than a regulated drawing or elongation of the riband in the interval betwixt a , b , and c , d , and a condensation of the filaments as they glide over each other, to a ume a straight parallel direction. In like manner the drawing may be repeated by giving the rollers, e , f , a greater surface speed than that of the rollers, c and d . This increase of velocity may be produced, either by enlarging the diameter, or by increasing the number of turns in the same time, or finally by both methods conjoined. In general the drawing-machine is so adjusted, that the chief elongation takes place between the second and third pairs of rollers, while that between the first and second is but slight and preparatory. It is obvious, besides, that the speed of the middle pair of rollers can have no influence upon the amount of the extension, provided the speed of the first and third pair remains unchanged. The rollers, a , b , and c , d , maintain towards each other continually the same position, but they may be removed with their frame-work, more or le , from the third pair, e , f , according as the length of the cotton staple may require. The distance of the middle point from b and d , or its line of contact with the upper roller, is, once for all, so calculated, that it shall exceed the length of the cotton filaments, and thereby that these filaments are never in danger of being torn asunder by the second pair pulling them while the first holds them fast. Between d and f , where the greatest extension takes place, the distance must be as small as it can be without risk of tearing them in that way; for thus will the uniformity of the drawing be promoted. If the distance between d and f be very great, a riband pa ing through will become thinner, or perhaps break in the middle; whence we see that the drawing is more equable, the shorter is the portion submitted to extension at a time, and the nearer the rollers are to each other, supposing them always distant enough not to tear the staple. The under rollers b d f are made of iron, and, to enable them to lay firmer hold of the filaments, their surfaces are fluted with triangular channels parallel to their axes. The upper rollers, a c e , are also made of iron, but they are smooth, and covered with a double coating, which gives them a certain degree of softne and elasticity. A coat of flannel is first applied by sewing or gluing the ends, and then a coat of leather in the same way. The junction edges of the leather are cut slanting, so that when joined by the glue (made of isingla di olved in ale) the surface of the roller may be smoothly cylindrical. The top rollers are sometimes called the pre ers , because they pre by means of weights upon the under ones. These weights are suspended to the slight rods k k′ ; of which the former operates on the roller e alone, the latter on the two rollers a and e together. For this purpose the former is hung to a C shaped curve i , whose upper hook embraces the roller e ; the latter to a bra saddle h , which rests upon a and c . A bar of hard wood, g , whose under surface is covered with flannel, rests, with merely its own weight, upon the top rollers, and strips off all the loose hanging filaments. Similar bars with the same view are made to bear up under the fluted rollers b d f , and pre against them by a weight acting through a cord pa ing over a pulley. Instead of the upper dust-covers, light wooden rollers covered with flannel are occasionally applied. Were the drawing of a riband continued till all its fibres acquired the desired degree of parallelism, it would be apt, from exce ive attenuation, to tear acro , and thereby to defeat the purpose of the spinner. This dilemma is got rid of in a very simple way, namely, by laying several ribands together at every repetition of the proce , and incorporating them by the pre ure of the rollers. This practice is called doubling . It is an exact imitation of what takes place when we draw a tuft of cotton wool between our fingers and thumb in order to ascertain the length of the staple, and replace the drawn filaments over each other, and thus draw them forth again and again, till they are all parallel and of nearly equal length. The doubling has another advantage, that of causing the inequalities of thickne in the ribands to disappear, by applying their thicker to their thinner portions, and thereby producing uniformity of substance. IMG:4147767755307473660_illo0352.png:Drawing frame The drawing frame, as shown in section in figs. 328. 330. , and in a back view in fig. 329. , will require, after the above details, little further explanation. l l are the weights which pre down the top rollers upon the under ones, by means of the rods k k′ and hook i . Each fluted roller is, as shown at f , fig. 329. , provided in the middle of its length with a thinner smooth part called the neck , whereby it is really divided into two fluted portions, represented by e e in the figure. Upon this middle neck in the pre ure rollers, the hook i and the saddle h immediately bear, as shown in the former fig. 328. The card-ends, to the number probably of six, are introduced to the drawing frame either from tin cans, placed at e e , fig. 330. , and at A , fig. 329. , or from lap-bobbins; and, after pa ing through it, the ribands or slivers are received either into similar tin cans, as g , or upon other lap-bobbins upon the other side. These appendages may be readily conceived, and are therefore not exhibited in all the drawings. Three of the slivers being laid together, are again introduced to the one fluted portion a b , fig. 328. , and three other slivers to the other portion. The sloping curved tin or bra plate s , fig. 329. , with its guide pins t , serves to conduct the slivers to the rollers. When the two threefold slivers have pa ed through between the three pairs of rollers, and been thereby properly drawn, they run towards each other in an oblique direction, behind the last roller pair e f , fig. 328. , and unite, on i uing through the conical funnel m , fig. 329. , into a single riband or spongy sliver; which is immediately carried off with equable velocity by two smooth cast-iron rollers, n o , fig. 329. and 330. and either dropped into a can, or wound upon a large bobbin. The surface speed of these rollers is made a trifle greater than that of the delivery drawing rollers, in order to keep the portion of sliver between them always in an extended state. Four fluted drawing portions are usually mounted in one drawing frame, which are set a-going or at rest together. To save all unnece ary carrying of the cans from the back to the front of the frame, the drawing heads are so placed, that the first and third, discharge their slivers at the one side, and the second and fourth at the other. By this arrangement, the cans filled behind one head, are directly pushed aside in front of the next drawing head; by which alternate distribution the work goes on without interruption. The fast pulley u , fig. 330. , by which the whole machine is driven, derives its motion from the main shaft of the mill by means of the band w . The similar pulley x , which sits loose upon the axis, and turns independently of it, is called the loose pulley; both together being technically styled riggers . When the operative desires to stop the machine, he transfers the band from the fast to the loose pulley by means of a lever, bearing a fork at its end, which embraces the band. Upon y , four pulleys such as x are fixed, each of which sets in motion a drawing head, by means of a band like w going round the pulleys x and u . On account of the inverted position of the heads, which requires the motion of u to be inverted, the bands of the first and third heads are open, but those of the second and fourth are cro ed. Every head is provided with a loose pulley v , as well as the fast pulley u , in order to make the one stop or move without affecting the others. The shaft of the pulley u is the prolonged shaft of the backmost fluted roller f . It carries besides a small pulley q , which, by means of the band r , and the pulley p , fig. 329. , sets in motion the undermost condensing roller o . The upper roller n , pre es with its whole weight upon it, and therefore turns by friction. The toothed wheel-work, by which the motions are communicated from the backmost fluted roller to the middle and front ones, are seen in fig. 330. The wheel f , fig. 328. , of 20 teeth, works in a 44-toothed carrier-wheel, on whose axis there are two smaller wheels; 2 with 26 teeth, and 1 with 22 teeth. The wheel d , fig. 330. , of the middle roller, and the wheel b of the front roller, are set in motion by other carrier wheels; the first has 27 teeth, and the last 40. For every revolution of b , the roller d makes nearly 1 3 ⁄ 4 turns, and the roller f , 4 revolutions. The top rollers revolve, as we have stated, simply by the friction of contact with the lower ones. Now suppose the diameter of the rollers b and d to be 1 inch or 12 lines, that of f , 1 1 ⁄ 4 inches or 15 lines, the surface velocities of the three pairs of rollers in the series will be as 1, 1 3 ⁄ 4 , and 5. Every inch of the cotton sliver will be therefore extended between the first and second pair of rollers into 1 3 ⁄ 4 inches, and between the second and third or delivery pair into 5 inches; and after the sliver has pa ed through all the four drawing heads, its length will be increased 625 times = 5 × 5 × 5 × 5. The further the drawing proce is pushed, the more perfectly will its object be accomplished; namely the parallelism of the filaments. The finene of the appearance of the sliver after the last draught depends upon the number of doublings conjointly with the original finene and number of drawings. The degree of extension may be increased or diminished, by changing the wheels in fig. 330. , for others with a different number of teeth. Thus the grist or finene of the sliver may be modified in any desired degree; for, when the subsequent proce es of the mill remain the same, the finer the drawings the finer will be the yarn. For spinning coarse numbers or low counts, for example, six card-ends are usually transmitted through the first drawing head, and converted into one riband. Six such ribands again form one in the second draught; six of these again go together into the third sliver; and this sliver pa es five-fold through the last draught. By this combination 1080 of the original card-ends are united in the finished drawn sliver = 6 × 6 × 6 × 5. The finene of the sliver is, however, in consequence of these doublings not increased but rather diminished. For, by the drawing, the card-end has been made 625 times longer, and so much smaller; by the doubling alone it would have become 1080 times thicker; therefore the original grist is to the present as 1, to the fraction 625 ⁄ 1080 ; that is, supposing 1072 feet of the riband delivered by the card to weigh one pound, 625 feet, the sliver of the last drawing, will also weigh a pound, which corresponds in finene to number 0·24, or nearly 1 ⁄ 4 . The rearmost or last drawing roller has a circumference of nearly 4 inches, and makes about 150 revolutions per minute; hence, each of these drawing heads may turn off 35,000 feet of sliver in 12 hours. Some manufacturers have lately introduced a double roller beam, and a double draught at the same doubling, into their drawing frames. I have seen this contrivance working satisfactorily in mills where low counts were spun, and where the tube roving frame was employed; but I was informed by competent judges, that it was not advisable where a level yarn was required for good printing calicoes. The lo which the cotton suffers in the drawing frame is quite inconsiderable. It consists of those filaments which remain upon the drawing rollers, and collect, in a great measure, upon the flannel facing of the top and bottom cleaner bars. It is thrown among the top cleanings of the carding engine. When from some defect in the rollers, or negligence in piecing the running slivers, remarkably irregular portions occur in the ribands, these must be torn off, and returned to the lap machine to be carded anew. The fifth operation may be called the first spinning proce , as in it, the cotton sliver receives a twist; whether the twist be permanent as in the bobbin and fly frame, or be undone immediately, as in the tube-roving machine. In fact, the elongated slivers of parallel filaments could bear little further extension without breaking asunder, unle the precaution were taken to condense the filaments by a slight convolution, and at the same time to entwine them together. The twisting should positively go no further than to fulfil the purpose of giving cohesion, otherwise it would place an obstacle in the way of the future attenuation into level thread. The combination of drawing and twisting is what mainly characterizes the spinning proce es, and with this fifth operation therefore commences the formation of yarn. As however a sudden extension to the wished-for finene is not practicable, the draught is thrice repeated in machine spinning, and after each draught a new portion of torsion is given to the yarn, till at last it po e es the degree of finene and twist proportioned to its use. The preliminary spinning proce is called roving . At first the torsion is slight in proportion to the extension, since the solidity of the still coarse sliver needs that cohesive aid only in a small degree, and loosene of texture must be maintained to facilitate to the utmost the further elongation. IMG:4147767755307473660_illo0354.png:Roving frame Fig. 331. is a section of the can roving frame, the ingenious invention of Ark wright, which till within these 14 years was the principal machine for communicating the incipient torsion to the spongy cord furnished by the drawing heads. It differs from that frame in nothing but the twisting mechanism; and consists of two pairs of drawing rollers, a and b , between which the sliver is extended in the usual way; c are brushes for cleaning the rollers; and d is the weight which pre es the upper set upon the lower. The wiping covers (not shown here) rest upon a b . The surface speed of the posterior or second pair of rollers is 3, 4, or 5 times greater than that of the front or receiving pair, according to the desired degree of attenuation. Two drawn slivers were generally united into one by this machine, as is shown in the figure, where they are seen coming from the two cans e e , to be brought together by the pre ure rollers, before they reach the drawing rollers a b . The sliver, as it escapes from these rollers, is conducted into the revolving conical lantern g , through the funnel f at its top. This lantern-can receives its motion by means of a cord pa ing over a pulley k , placed a little way above the step on which it turns. The motion is steadied by the collet of the funnel f , being embraced by a bra busk. Such a machine generally contained four drawing heads, each mounted with two lanterns; in whose side there was a door for taking out the conical coil of roving. The motion imparted to the back roller by the band pulley or rigger m , was conveyed to the front one by toothed wheel work. The vertical guide pulley at bottom n , served to lead the driving band descending from the top of the frame round the horizontal whorl or pulley upon the under end of the lantern. The operation of this can-frame was pleasing to behold; as the centrifugal force served both to distribute the soft cord in a regular coil, and also to condense a great deal of it most gently within a moderate space. Whenever the lantern was filled, the tenter carried the roving to a simple machine, where it was wound upon bobbins by hand. Notwithstanding every care in this transfer, the delicate texture was very apt to be seriously injured, so as to cause corresponding injuries in every subsequent operation, and in the finished yarn. Me rs. Cocker and Higgins, of Salford, had the singular merit, as I have said, of superseding that beautiful but defective mechanism, which had held a prominent place in all cotton mills from almost the infancy of the factory system, by the following apparatus.