 
T The last process of manufacturing, and the one in which all the preceding ones culminate, is weaving. This has for its object the combination of the warp and weft yarns, interlacing one with the other in such manner as to produce a firm texture, fitted for the varying uses to which cotton cloth is adapted—for warmth, for ornament, for trade purposes—for sale. The power looms of the present day, as employed in the cotton industry, vary very little in construction in the most widely separated districts, unless for very different classes of work, then what modifications are required consist of extra mechanism added to our common type—the plain loom. The Plain Loom.The machine required for the weaving of plain cloth, or cloth in which each end of weft and twist is interwoven alternately and on the face of which no figure is shown, is simple. The warp yarn is contained on a beam, the weft is placed in a shuttle, and the loom consists of the necessary framework and mechanism for holding the warp in the required position, passing the weft between alternate warp threads. A general view of the loom is shown in Fig. 21, whilst a detailed representation is given in Fig. 22. FIG. 21.—PLAIN LOOM. (Front View.) FIG. 22.—PLAIN LOOM. (Back View.) In the process of weaving it is necessary to hold the warp somewhat tightly, each portion at the same tension, and to obtain this condition the cloth is pulled forward by the taking-up roller as it is woven; but the warp is held back by the friction of weighted chains or ropes on the collars of the beam. The warp passes upwards from the beam, over the back rest, and thence to the back of the healds; between the back rest and healds are the lease rods—a large one with a smaller rod nearer the healds. By means of these rods the warp is separated into equal portions, two ends passing alternately over or under the thick rod; those passing over the thick one also run under the thin rod. The rule commonly observed for four healds is to have the ends passing the first and the third heald SUNDRY FITTINGS FOR LOOM.—FIG. 21.
PLATE V.—PARTS OF PLAIN LOOM. To face p. 56. Shedding.Shedding is very important, and more so in figured cloth than in plain; for it is by the shedding in its varied character that fancy cloth is principally produced. For plain cloth, a two-leaved or two-plated tappet is fixed on the tappet shaft, acting on a bowl fixed to the end of a lever, as shown in sketches of looms. There is one lever or treadle to each plate, and the heald worked by it is attached at the centre by wire, and a small corded cross-piece of wood, called a lamb. From the sketch it will be seen that, as the tappets revolve, the healds are alternately lifted and depressed, opening the shed in the warp. The shed for one pick will have the front heald at the top, and the back one at the bottom; whilst for the next pick their positions are reversed. The tappets are of rather peculiar form, a common shape for plain being shown at Fig. 28. Working on the centre S the eccentricity obtained is employed in depressing the healds, but by an intermittent movement. The shed must be opened quickly to economise time, but must be left open sufficiently long to enable the shuttle being picked through. A reference to the shape of the plate in Fig. 28 will show this. From N to H is the portion for depressing the heald, from G to H being an arc of a circle and the part by which the heald is held stationary, while G M corresponds inversely with F N, and allows the heald to rise. It is necessary for the eccentricity to be equal at each shed, a point which may be tested by noticing if the sway of the beam is the same at each shedding. To get this, the treadles must be level when the healds are, and the centre of the bowl directly under the centre of the shaft. The bowl should be in contact with the tappet during the whole revolution, and thus give an easy tread—jerky motion in either treading or picking being very detrimental to good weaving. A good shed should be almost as large as the shuttle at the point where it passes through, quite clear from obstructions of any kind, and the lower half of it not too low, or, A point regarding which weaving technologists often enter into profuse arguments and diagrammatic illustration, may here be summed up in a few words. The line of warp when the healds are level should be below a line drawn from the temple to the back rest, and the lower the healds are in this respect the better is the cover on the cloth, although attention must be given to the remarks in a previous paragraph regarding bottoming. Whether the lowness of the warp line is produced by depressing the healds or raising the back rest is immaterial. When plain cloth is woven in a twill loom, the tappets act above the centre of the treadle, and of course are of smaller size, the healds being connected to the end of the lever opposite to the fulcrum. The calculation of the size of the shed from given dimensions of the tappets and treadles forms a good example in leverage. Suppose the stroke of the tappet, or the distance through which it moves the treadle bowl (represented in Fig. 28), between the outer and inner circles is 3-1/2 inches. The treadle is 30 inches long, the treadle bowl being 25 inches from the treadle pin, and the healds connected 15 inches from the pin or fulcrum at N. Then the movement of the heald from its highest to its lowest level is equal to the distance moved through by the point N—i.e., 2·1 inches—for if the bowl moves 3-1/2 inches, the point N moves (3-1/2 × 15) / 25 = 2·1 inches. This gives the size of the shed at the healds. Suppose the heald in question is 7 inches from the fell of the cloth, the shuttle passing through the shed 2 inches nearer to the cloth, then the size of the shed at the heald multiplied by 5 and divided by 7 gives its size at the point where the shuttle passes through, or (2·1 × 5) ÷ 7 = 1·5 inches. There is a slightly different shedding arrangement adopted in some looms, frequently so in Yorkshire, but rarely in Lancashire. This is the Bradford gear shown in Fig. 23. The tappets are placed outside of the loom, and the treadles are connected to the healds through FIG. 23.—BRADFORD LOOM. Picking.Among cotton looms the over-pick or Blackburn pick is commonest. Attached to the tappet shaft are picking plates, one at each side of the loom. As the picking arrangement at one side is similar to that at the other, a single description applies to both. The picking plate ends in a point and acts on an upright picking shaft through a stud affixed to the latter. The point is removable and is lengthened in broader looms about 1/8 inch for every 10 inches wider reed space. At the top of the picking shaft is a picking stick, an arm of some It will be easily seen how the revolution of the picking plate actuates quickly the picking shaft, and consequently the end of the stick, with an increased speed. The blow is transmitted to the picker and the shuttle driven across the slay into a similar box at the other side. When a new shed has been formed by the healds it is driven back again. A smooth pick is most desirable, and for this reason the stud on the picking shaft must be set so as to receive a smooth side blow from the plate, neither a downward nor an upward one. This is a point in the tackling of looms which receives the attention of every good overlooker. The shuttle used in the ordinary classes of cotton goods is of box or some other heavy wood pointed and tipped at each end with iron. The usual length is about 13 inches and depth 1-3/8 inch. Care must be taken that it is smooth at all parts where it comes in contact with the twist, free from knots or other flaws, which, should they give, would make havoc among the threads. The weft is in cop form, and fits on a peg inside the shuttle, the loose end from the cop nose being drawn Beating Up.The shot or pick of weft often being put through the shed, is at a distance of five inches from the woven cloth, and requires pushing up into close contact with it. The motion of the slay performs this operation. As explained on page 60, the slay is a beam of wood carrying a reed, and having a reciprocating motion to and from the fell of the cloth, imparted to it by the cranks on the shaft (Figs. 22 and 43.) The beam is supported on two vertical rods, called slay swords, attached near the bottom of the loom to a vibrating or “rocking” shaft. The slay is away from the cloth or front centre a sufficient time to give opportunity for the propulsion of the shuttle through the shed. Were the crank-shaft at the same level as the slay-sword pin, the dwell at each end of the stroke would be exactly equal—a dwell of some duration, however slight, it is obvious, there must be. However, the centre of the crank-shaft is at a lower level than that of the connection of the crank-arm with the slay-sword ears, and thus the slay dwells longer at the healds than at the cloth. As the slay makes some 200 strokes per minute, the variations of speed at the back and front centres are scarcely observable, but by means of exact measurements a certain amount of dwell may be traced at the back centre. By describing a circle to represent the movement of the crank, and at a distance from it drawing to scale an FIG. 24. The shuttle race is made of hard wood laid on the beam, and in addition to the depression at the centre is also rather wider at the middle of the race—at that point bulging out slightly against the reed, which is kept in contact with it by the slay cap at the top and the reed case at the bottom. Care must be taken to keep the ends of the reed from projecting in front of backboard, or the shuttle will be thrown out. Loose and Fast Reeds.To obtain a firm blow at the cloth the reed is made to strike it at right angles, for if the angle were more obtuse or acute a loss of force would be entailed by a consequent downward or upward stroke imparted to the cloth, the line of action not being in the same plane as the line of reaction. With regard to the firmness of the beating up, we have to consider the merits of fast and loose reed looms. In weaving, an accident which not infrequently occurs is the stoppage of the shuttle when it has only traversed a portion of the distance across the warp. A case of this shuttle trapping causes the breakage of more or fewer ends, and consequently arrangements are made for preventing much damage, either by arresting the motion of the loom suddenly, in case of a fast reed, or by having a reed hanging loosely behind the shuttle so as to give way in case of a “mash.” The latter arrangement is preferable, as there is not the sudden concussion given to the loom, which causes the vibration and straining of every part, so objectionable in the fast reed loom; the loose reed can, however, only be used for light and medium cloths, as the reed is too lightly fixed to give a strong beat-up. In the case of the loose reed, the slay cap holds the upper part of the reed in a slot, the bottom part being pressed against the shuttle race by a strip of wood (completing the reed case) attached to the stop rod. When at the fell of the cloth, the stop rod is held firmly by a spring, and a fairly strong blow can be given to the FIG. 25. Fast Reed Loom.—Here the loom is stopped suddenly in case of the shuttle being stopped in the shed. From Fig. 25 the arrangement will be understood. A swell attached to the shuttle box is placed so as to project into it when the box is empty, and through an L-lever A drops a catch so as to strike the frog B and arrest the motion of the slay. The frog moves a short distance and puts the loom brake in action before checking the motion Take-up Motion.FIG. 26. Among cotton looms the positive take-up motion is generally used. The cloth as woven is, by this arrangement, drawn on the cloth roller a certain distance at every pick, the amount of take-up being regulated by wheels. Fig. 26 shows a sketch of the arrangement. The construction is similar for almost all looms, but there are The method of obtaining the dividend for any ordinary gear is— (Rack wheel × Carrier wheel × Beam wheel)/(Pinion wheel × number of 1/4 inches in circumference of taking-up roller) afterwards adding 1-1/2 per cent. for shrinkage of the cloth after being released from the tension of the loom. Thus, Dickinson’s gear is— (50 × 75 × 100) / (12 × 60) = 520. The principal gears in use in Lancashire are:—
Pickles’ gear also has a swing pinion 24, and 2 change wheels; to find the change wheel required, multiply the change wheel on the rack stud by the picks per quarter inch, and divide by 9—
By using this motion, which is shown on Fig. 23, both heavy and light pick cloth can be woven without a great variation in the wheels. To weave heavy pick cloth with, say, the first-named motion, the rack wheel might be increased to 60 from 50, and the dividend would then be 634. In some looms a letting-off motion works in conjunction with the take-up, to release the yarn on the beam at a fixed rate. The Weft Stop Motion.A reference to the invention of this very ingenious and useful apparatus is made in Chapter I. Its object is to stop the loom on the breakage of the weft, or when the cop is finished. Unsightly gaws or goals in the fabric are thus prevented, and the weaver enabled to attend to more looms. A lever is fixed to the breast beam (Fig. 27), hinged at one end, and arranged so as to rest against the starting handle E. The lever carries a bent fork C, which FIG. 27. When there is weft in the loom the fork is prevented by the thread from passing through the grid, and its back part is thus lifted clear of the hammer. Should the weft be broken, the loom is stopped thus: The sector raises the greyhound tail at the moment that the slay is at the fore centre, and there being no weft to raise the fork, it is caught by the hammer, and the lever to which the fork is attached pulled forward, when, as previously referred to, the spring handle is released and the loom stops. Manifestly the motion must be set so as to act when the shuttle is at the fork side of the loom. The Brake.A good brake contributes greatly to the manufacture of even cloth; should the stopping arrangements be ineffective, thin places and cracks will be inconveniently numerous. Usually the brake is a simple lever acting on a brake pulley at one end, whilst at the other it is regulated by an inclined bracket connected with the starting handle. When the handle is pushed forward, the brake lever is lifted; when the knocking-off takes place the end of the brake lever drops and the leathers come in contact with the pulley, stopping the loom. Additional brake power may be made by altering the leathers or weighting the brake lever. Temple Rollers.The cloth as it is woven tends to contract in width in consequence of the tension at which it is wrought lengthway, and to counteract this, temple rollers are used. For commoner heavy fabrics the roller and trough is used, and consists of a fluted roller cut in the manner of a screw at either end, one end with left-hand thread and the opposite end a right-hand. Thus a spiral row of points is left at each end of the roller, and it is fixed in the loom, so that as the roller revolves the points distend the cloth. The roller is fixed in a trough for convenience in attaching to framework. Lighter fabrics are woven with Timing.All the contrivances just described are required to work harmoniously in order to produce the desired results, each coming into action at the proper time. In plain cloth weaving, when the crank is at the fore centre, the reed touches the cloth at right angles, and the healds are slightly open, forming a new shed. As the slay moves backwards just in front of the bottom centre, the picking band is tight and just commencing to move the shuttle. At this point the healds are full open and remain so until the crank has passed the back centre, when, as the shuttle has arrived in the opposite box, the shed begins to close. Before the slay has reached the front again, indeed when just past the top centre, the healds are level; an advantage is thus gained in having the rods crossed on the weft at the time it is beaten up, holding it firmly. The sector lifts the greyhound tail for the weft stop motion at the moment that the reed touches the cloth, when the fork would be lifted if there were weft in the loom. This only happens, of course, every alternate pick, when the shuttle is at the fork side of the slay. Generally the monkey tail on the slay sword moves the take-up pawl as the slay moves back, just dropping the holding catch as the crank reaches the back centre. The reed is held tightly in a loose reed loom when the slay approaches the front. Of course, the timing of the motion varies under different circumstances; if cloth is being woven as wide as the loom will possibly admit of, or if the shuttle boxes be short, then picking necessarily The Position and Fixing of the Looms.In a weaving shed the looms are driven from shafting running parallel to the looms when looked at lengthway. Drums on the line shafts drive the loom pulleys by means of straps. Of these pulleys there are two, generally about 9 inches diameter for a 40-inch loom. One pulley is loose on the shaft, the other keyed to it—the former to carry the strap when the loom is stopped. The looms are in groups of four, with an occasional row of couples for two or three loom weavers. The four arrangement is adopted for convenience to the weaver, as the looms having the starting ends contiguous, he has little walking for the purpose of setting on the machines. Thus, two “hands” of loom are required, those with the starting handle at the right-hand side being named right-hand looms, and vice versÂ. There is little difference in construction—the crank-shaft is longer in one than the other for the purpose of having two straps on one driving drum. Many parts, such as crank-shafts, slays, shuttles, forks, brackets, etc., are required to be of two “hands,” each for its own hand of loom. In view of a case of having to remove looms or fix new ones, a few remarks on the general arrangements for fixing them may not be unacceptable. The line shaft runs over the space between the warp beams of the looms. A line must be marked on the floor with chisel or other convenient instrument parallel to this shaft and exactly below it. By dropping a plumbline from various parts of the shaft, the starting points can be obtained for stretching a line to mark from. The same arrangement is adopted at every third shaft, as the intermediate ones may be measured. From these lines the distance at which the The ends of the loom must be set parallel also, so that on looking down the shop a straight row of machinery will be observed. A line for setting the outside loom feet may be measured from the pillars, after getting the first pair of looms in suitable position. To test the accuracy of these measurements, the breast beam of each loom, as fixed, must be examined in a line with the breast beam of the previously deposited one. After the correct position is obtained, each loom must be levelled up by thin sheets of wood packing placed under the feet as required. Holes are then drilled in the floor, wood pegs inserted, and long iron nails driven home. A good passage round each group of four looms cannot be too greatly valued, and likewise a broad alley here and there running the whole length of the shed. Loom Tackling.A loom requires a considerable amount of repairs and renewals, the performance of which is delegated to an overlooker (sometimes called a tackler or tuner) placed over each hundred looms. If on fancy goods, fewer looms are under the control of one man; if plain narrow goods are woven, more. His work is to keep the looms supplied with warps, gait them up, repair or tackle the loom when necessary, provide weavers, and, especially in a small place, perform rather multifarious duties. When the weavers’ beam has been placed in the loom, having the healds and reeds attached to the warp, the overlooker draws the gears forward, placing a weight rope or chain round one beam ruffle, and, if a loomed beam, fixes the reed. The healds are slung loosely to the heald roller straps, and then the twist attached to the sand roller. If old healds are used, the lap end of a former cut is placed on the roller, and the warp tightened. If new healds have had the warp drawn in, a lap end is attached to the roller and the twist tied to it, care being taken to draw up any ends which may be ruffled. The temple is fixed so as to It is impossible to enumerate all the little points in the management of looms, which it is the overlooker’s duty to perform; and only long practical experience can teach their proper performance. However, neglecting the derangements, which cause faults in the cloth, and which will be treated of in the next chapter, we will refer to some of the commoner mishaps. The shuttle flying out of the loom is caused generally by some obstruction in the shed, floats, projecting reed, top of shed too low or bottom too high, or by a crooked spindle or bad picker. Cops flying off the shuttle peg may be attributed to too large holes in the cop, or shuttle spring too weak or unpacked. When the loom does not knock off when the weft is done, the fork may be bent and thus lifted by grate, an end of weft may be hanging to the shuttle sufficiently long to catch in the cloth and lift the fork. But for the cause of this, and also of the loom knocking off when weft is not broken, the weft stop-motion must be carefully watched. The picking may sometimes be so strong as to throw the shuttle out of the loom, or so weak as to allow it to be trapped by the closing shed. By judicious setting of plate and bowls, any desired result may be obtained. When by the shuttle binding too tightly in the box, etc., a fracture of the weft is made, it is said to be The Weavers.The average weaver runs four looms, but in many sheds provision is made for three, or even two-loom weavers, whilst qualifying themselves for the higher number. In some North-East Lancashire towns five and six-loom weavers are not infrequent on narrow strong goods. The weaver’s duties require some little skill, and consist of piecing up the broken ends of warp and drawing them through the heald and reeds, filling the shuttles with weft and placing them in the loom as those in working become empty, oiling, doffing “cuts,” putting in the coloured headings—an important part of dhooty weaving—oiling, and performing simple repairs. The wages obtainable on ordinary goods, such as shirtings and printers, should not be less than 11s. per pair, to give satisfactory results, while 12s. 6d. per pair on dhooties and simplest fancy goods is good. The waste in this process is important, four per cent. being allowable on common yarns, say 36’s, this being reduced on finer and consequently better copped yarns (weft). The foregoing remarks apply to the weaving of plain cloths only, and that by the most usual methods. In any process whatever, it may be that some variation will be found to exist, and, before concluding this part of the subject, the modifications of the one standard type of loom may be referred to. In shedding, the tappets may sometimes be placed on a third shaft, driven from the tappet shaft, and termed a twill shaft, because by altering the tappets and the speed the loom may be made available for weaving twills. When the tappets are fixed to the twill shaft they are smaller than those fixed to the tappet shaft. Setting Out Tappet.The setting out of a tappet is an important problem. Two circles must be described round the same centre, the difference in the radii being the stroke of the tappet—thus, FIG. 28. The movement of the rising healds commences, however, before the falling heald has come to a pause; therefore we must trespass into the lower half to an extent equal to E G and H F, thus obtaining by drawing a diameter through G and the centre, also through H and the centre, This is the theoretical construction of a plain tappet, from M to N being the dwell from the heald when up. N to H the depression, and H to G the dwell for the heald when down; and it will be noted, that although G H is apparently larger than N M, the time of dwell is the same in each case, in consequence of the arc N M being so much nearer the centre. In practice, the hollows N and M may be found rather fuller than shown here. This method of construction applies to tappets with an increased number of picks to the round, a point which will be found described in Chapter VI. The speed of tappets is an important subject for calculation in connection with the loom. When the tappets are on the tappet shaft they are always plain, and are driven at half the speed of the crank-shaft, in consequence of the latter shaft only representing one pick, while the tappet shaft, (13 × 25)/65 = 325/65 = 65/13 These, or a multiple of these, are the wheels required, which may be proved:— (65 × 65)/(25 × 13) = 13 picks to a round. Split Cloths and Motions.Split cloths are sometimes woven in the ordinary loom when narrow widths are required and a perfect selvage is not a necessity. Thus, a 40-inch loom may weave a cloth with a few empty dents at the centre, whilst on each side of the space thus caused the warp threads are crossed (on the gauze principle) between each pick to make a firmer selvage than could be got by ordinary lifting. The weft threads are then slit along this space by a sharp knife, giving two cloths, each 20 inches wide. One system of forming the selvage is by having an extra loop attached to the top stave of one heald, and carrying a thread which is drawn through the other heald. By correct drafting this thread can be made to lift at every pick first on one side of its neighbouring warp thread and then on the other. The same object is attained in a split motion, patented by J. & R. Shorrock, and Taylor, of Darwen. By means of eyeletted straps revolving round a tightened warp thread, the doup or crossing threads drawn through the eyelets make a very firm selvage when slit. The picking motions require a few further remarks. For some goods, especially fancies, the under pick is used. In this case the picking stick is rather longer than the slay sword, and is fixed parallel to it, projecting from the rocking shaft through the shuttle box and picker. The loom, Plate VII., possesses the under-pick arrangement. It is driven by means of the picking plate acting downwards on a lever centred at one end, whilst carrying at the other end a strap fixed to the picking stick about four or five inches from the bottom end of it. The scroll or side pick is a favourite one for velvet looms. The picking plates are fixed on the crank-shaft, and consist simply of a disc of metal carrying a lug so as to catch against a latch or lug on a short inclined shaft at the loom side. This shaft at the bottom end actuates by means of a strap and picking stick fixed as in the under-pick loom. Obviously, the picking from each side of the loom must be done alternately, and the plates at the loom side are arranged so as to act only once in two revolutions of the crank-shaft. This motion is obtained by means of a scroll plate on the crank-shaft carrying a groove forming an inner and outer ring in the plate; in this works a slide in the inner ring for one pick, then traversing the outer part of the groove for the second pick. This slide regulates the latch on the short shaft. When in the outer ring the latch is lowered so as to be caught by the lug on the picking plate, but is out of the way when the sliding piece is in the inner ring. Of course, when the slide is in the inner part of the groove at the right-hand side of the loom, the slide of the left-hand picking scroll is in the outer ring, so as to pick alternately. This picking arrangement is very compact. PLATE VI.—SHEDDING MOTIONS. To face p. 79. Speeds.—Average Speed of New Looms.
On goods with ordinary headings, the stoppages for changing shuttles, piecing ends, etc., should not be more than one minute in twelve, or 8 per cent. Reed Space.The reed space of a loom is measured from backboard on the one side to the fork grate on the other. Thus, what is called a 40-inch loom measures 45 inches reed space, and in it it is usual to weave cloth up to 41 inches wide, although it is possible to weave 42-1/4-inch cloth in it. A 26-inch loom has a 30-inch reed space, and will weave to 28 inches. In wider looms the reed space is about six inches above the nominal size of the loom. Top Motions.In Plate VI. are shown a number of top motions to keep the healds tight when worked from below. Each is self-explanatory, and by imagining the effect of changing the heald or healds which are up for others, the value of each arrangement will be seen. For example—take H, a 3-shaft motion, two up. If No. 2 be required up and No. 3 down, the change is made without any movement of the top pulley; if No. 1 be required down and the other two up, it will be drawn down a distance equal to the size of the shed—say 2 inches; whilst the small pulley being connected to a step pulley on the larger one, is only lifted half that distance—say 1 inch. Now, if the small one be raised 1 inch and No. 3 heald be kept still, No. 2 heald will lift 2 inches—the height desired. It will be noted that a top motion is adapted only for one number of healds, and that the same number must be up in successive picks. Should different numbers be up at consecutive picks, a spring top as at S is used. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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