FIG. 21 A LINE OF SPINNING FRAMES
The front part of the builder rail is provided with grooves into one of which the temper-band is placed so that the band itself is in contact with a groove near the base of the bobbin flange. A varying amount of resistance or tension on the bobbin is required in virtue of the varying size of the partially-filled bobbin, and this is obtained by placing the temper-band successively in different groves in the builder so that it will embrace a gradually increasing arc of the spinning bobbin, and thus impart a heavier drag or tension.
The spinning frames in Fig. 20 are arranged with the ends of the frame parallel to the pass, whereas the end frames in Fig. 21 are at right angles to the pass, and hence an excellent view of the chief parts is presented. The full rove bobbins are seen distinctly on the pegs of the creel in the upper part of the figure, and the rove yarns from these bobbins pass downwards, as already described, until they ultimately enter the eyes of the flyer arms to be directed to and wound upon the spinning bobbins. The flyers--at one time termed throstles--are clearly visible a little above the row of temper weights. The chief parts for raising the builder--cam lever, adjustable rod, chain and wheel--are illustrated at the end of the frame nearest the observer.
[CHAPTER XI. TWISTING AND REELING]
In regard to cloth manufacture, most yarns are utilized in the form they leave the spinning frame, that is, as single yarns. On the other hand, for certain branches of the trade, weaving included, it is necessary to take two, three, or more of these single yarns and to combine them by a process technically termed twisting, and sometimes "doubling" when two single yarns only are combined.
Although the commonest method, so far as weaving requirements go, is to twist two single yarns together to make a compound yarn, it is not uncommon to combine a much higher number, indeed, sixteen or more single yarns are often united for special purposes, but, when this number is exceeded, the operation comes under the heading of twines, ropes and the like. The twist or twine thus formed will have the number of yarns regulated by the levelness and strength required for the finished product. The same operation is conducted in the making of strands for cordage, but when a number of these twines are laid-up or twisted together, the name cord or rope is used to distinguish them.[1]
[Footnote 1: See Cordage and Cordage Hemp and Fibres, by T. Woodhouse and P. Kilgour.]
When two or three threads are united by twisting, the operation can be conducted in a twisting frame which differs little from a ordinary spinning frame, and hence need not be described. There may be, however, appliances embodying some system of automatic stop motion to bring the individual spindles to rest if one thread out of any group which are being combined happens to break. When several threads have to be twisted together, special types of twisting frames are employed; these special machines are termed "tube twisters," and the individual threads pass through holes suitably placed in a plate or disc before they reach the tube.
More or less elaborate methods of combining yarns are occasionally adopted, but the reader is advised to consult the above-mentioned work on Cordage and similar literature for detailed information.
When the yarn leaves the spinning frame, or the twisting frame, it is made up according to requirements, and the general operations which follow spinning and twisting are,--reeling, cop-winding, roll or spool winding, mill warping or link warping. The type or class of yarn, the purpose for which the yarn is to be used, or the equipment of the manufacturer, determines which of these methods should be used previous to despatching the yarn.
Reeling. Reeling is a comparatively simple operation, consisting solely of winding the yarns from the spinning or twisting bobbins on to a wide swift or reel of a suitable width and of a fixed diameter, or rather circumference. Indeed, the circumference of the reel was fixed by an Act of Convention of Estates, dating as far back as 1665 and as under:
"That no linen yarn be exported under the pain of confiscation, half to the King and half to the attacher."
"That linen yarn be sold by weight and that no reel be shorter than ten quarters."
The same size of reel has been adopted for all jute yarns. All such yarns which are to be dyed, bleached, or otherwise treated must be reeled in order that the liquor may easily penetrate the threads which are obviously in a loose state. There are systems of dyeing and bleaching yarns in cop, roll or beam form, but these are not employed much in the jute industry. Large quantities of jute yarns intended for export are reeled, partly because bundles form suitable bales for transport, and partly because of the varied operations and sizes of apparatus which obtain in foreign countries.
YARN TABLE FOR JUTE YARNS
90 inches, or 2-1/2 yards = 1 thread, or
the circumference
of the reel
120 threads or 300 yards = 1 cut (or lea)
2 cuts or 600 yards = 1 heer
12 cuts or 3,600 yards = 1 standard hank
48 cuts or 14,400 yards = 1 spyndle
Since jute yarns are comparatively thick, it is only the very finest yarns which contain 12 cuts per hank. The bulk of the yarn is made up into 6-cut hanks. If the yarn should be extra thick, even 6 cuts are too many to be combined, and one finds groups of 4 cuts, 3 cuts, 2 cuts, and even 1 cut. A convenient name for any group less than 12 cuts is a "mill-hank," because the number used is simply one of convenience to enable the mill-hank to be satisfactorily placed on the swift in the winding frame.
The reeling operation is useful in that it enables one to measure the length of the yarn; indeed, the operation of reeling, or forming the yarn into cuts and hanks, has always been used as the method of designating the count, grist or number of the yarn. We have already seen that the count of jute yarn is determined by the weight in lbs. of one spyndle (14,400 yds.).
For 8 lb. per spyndle yarn, and for other yarns of about the same count, it is usual to have provision for 24 spinning bobbins on the reel. As the reel rotates, the yarn from these 24 bobbins is wound round, say,
6 in. apart, and when the reel has made 120 revolutions, or 120 threads at each place from each bobbin, there will be 24 separate cuts of yarn on the reel. When 120 threads have been reeled as mentioned, a bell rings to warn the attendant that the cuts are complete; the reel is then stopped, and a "lease-band" is tied round each group of 120 threads.
A guide rod moves the thread guide laterally and slowly as the reeling operation is proceeding so that each thread or round may be in close proximity to its neighbour without riding on it, and this movement of the thread extends to approximately 6 in., to accommodate the 6 cuts which are to form the mill-hank.
Each time the reel has made 120 revolutions and the bell rings, the reeler ties up the several cuts in the width, so that when the mill-hank is complete, each individual cut will be distinct. In some case, the two threads of the lease-band instead of being tied, are simply crossed and recrossed at each cut, without of course breaking the yarn which is being reeled, although effectively separating the cuts. At the end of the operation (when the quantity of cuts for the mill-hank has been reeled) the ends of the lease-band are tied.
The object of the lease-band is for facilitating the operation of winding, and for enabling the length to be checked with approximate correctness.
When the reel has been filled with, say, twenty-four 6-cut hanks, there will evidently be 3 spyndles of yarn on the reel. The 24 mill-hanks are then slipped off the end of the reel, and the hanks taken to the bundling stool or frame. Here they, along with others of the same count, are made up into bundles which weigh from 54 lb. to 60 lb. according to the count of the yarn. Each bundle contains a number of complete hanks, and it is unusual to split a hank for the purpose of maintaining an absolutely standard weight bundle. Indeed, the bundles contain an even number of hanks, so that while there would be exactly 56 lb. per bundle of 7 lb. yarn, or 8 lb. yarn, there would be 60 lb in a bundle of 7-1/2 lb. yarn, and 54 lb. in a bundle of 9 lb. yarn.
The chief point in reeling is to ensure that the correct number of threads is in each cut, i.e. to obtain a "correct tell"; this ideal condition may be impracticable in actual work, but it is wise to approach it as closely as possible. Careless workers allow the reel to run on after one or more spinning bobbins are empty, and this yields what is known as "short tell." It is not uncommon to introduce a bell wheel with, say, 123 or 124 teeth, instead of the nominal 120 teeth, to compensate for this defect in reeling.
[CHAPTER XII. WINDING: ROLLS AND COPS]
The actual spinning and twisting operations being thus completed, the yarns are ready to be combined either for more elaborate types of twist, or for the processes of cloth manufacture. In its simplest definition, a fabric consists of two series of threads interlaced in such way as to form a more or less solid and compact structure. The two series of threads which are interlaced receive the technical terms of warp and weft--in poetical language, warp and woof. The threads which form the length of the cloth constitute the warp, while the transverse threads are the weft.
The warp threads have ultimately to be wound or "beamed" on to a large roller, termed a weaver's beam, while the weft yarn has to be prepared in suitable shape for the shuttle. These two distinct conditions necessitate two general types of winding:
(a) Spool winding or bobbin winding for the warp yarns.
(b) Cop winding or pirn winding for the weft yarns.
For the jute trade, the bulk of the warp yarn is wound from the spinning bobbin on to large rolls or spools which contain from 7 to 8 lb. of yarn; the weft is wound from the spinning bobbin into cops which weigh approximately 4 to 8 ounces.
Originally all jute yarns for warp were wound on to flanged bobbins very similar to, but larger than, those which are at present used for the linen trade. The advent of the roll-winding machine marked a great advance in the method of winding warp yarns as compared with the bobbin winding method; indeed, in the jute trade, the latter are used only for winding from hank those yarns which have been bleached, dyed or similarly treated. Fig. 22 illustrates one of the modern bobbin winding machines for jute made by Messrs. Charles Parker, Sons & Co., Dundee. The finished product is illustrated by two full bobbins on the stand and close to a single empty bobbin. There are also two full bobbins in the winding position, and several hanks of yarn on the swifts. Each bobbin is driven by means of two discs, and since the drive is by surface contact between the discs and the bobbin, an almost constant speed is imparted to the yarn throughout the process. An automatic stop motion is provided for each bobbin; this apparatus lifts the bobbin clear of the discs when the bobbin is filled as exemplified in the illustration.
The distance between the flanges of the bobbin is, obviously, a fixed one in any one machine, and the diameter over the yarn is limited. On the other hand, rolls may be made of varying widths and any suitable diameter. And while a bobbin holds about 2 lb. of yarn, a common size of roll weighs, as already stated, from 7 to 8 lb. Such a roll measures, about 9 in. long and 8 in. diameter; hence for 8 lb. yarn, the roll capacity is 14,400 yards.
Rolls very much larger than the above are made on special machines adopted to wind about six rolls as shown in Fig. 23. It is built specially for winding heavy or thick yarns into rolls of 15 in. diameter and 14 in. length, and this particular machine is used mostly by rope makers and carpet manufacturers. One roll only is shown in the illustration, and it is winding the material from a 10 in. x 5 in. rove bobbin. The rove is drawn forward by surface or frictional contact between the roll itself and a rapidly rotating drum. The yarn guide is moved rapidly from side to side by means of the grooved cam on the left, the upright lever fulcrumed near the floor, and the horizontal rod which passes in front of the rolls and upon which are fixed the actual yarn guides. This rapid traverse, combined with the rotation of the rolls, enables the yarn to be securely built upon a paper or wooden tube; no flanges are required, and hence the initial cost as well as the upkeep of the foundations for rolls is much below that for bobbins.
