The Jute Industry: From Seed to Finished Cloth Part 6

The completed chain from the warping mill or the linking machine is now taken to the beaming frame, and after the threads, or rather the small groups of threads, in the pin lease have been disposed in a kind of coa.r.s.e comb or reed, termed an veneer or radial, and arranged to occupy the desired width in the veneer, they are attached in some suitable way to the weaver's beam. The chain is held taut, and weights applied to the presser on the beam while the latter is rotated. In this way a solid compact beam of yarn is obtained. The end of the warp--that one that goes on to the beam last--contains the weaver's lease, and when the completed beam is removed from the beaming or winding-on frame, this single-thread lease enables the next operative to select the threads individually and to draw the threads, usually single, but sometimes in pairs, in which case the lease would be in pairs, through the eyes of the camas or HEALDS, or to select them for the purpose of tying them to the ends of the warp in the loom, that is to the "thrum" of a cloth which has been completed.

Instead of first making a warp or chain on the warping mill, or on the linking machine, and then beaming such warp on to the weaver's beam or loom beam as already described, two otherwise distinct processes of warping and beaming may be conducted simultaneously.

Thus, the total number of threads required for the manufacture of any particular kind of cloth--unless the number of threads happens to be very high--may be wound on to the loom beam direct from the spools.

Say, for example, a warp was required to be 600 yards long, and that there should be 500 threads in all. Five hundred spools of warp yarn would be placed in the two wings of a V-shaped bank, and the threads from these spools taken in regular order, and threaded through the splits or openings of a reed which is placed in a suitable position in regard to the winding-on mechanism. Some of the machines which perform the winding-on of the yarn are comparatively simple, while others are more or less complicated. In some the loom beam rotates at a fixed number of revolutions per minute, while in others the beam rotates at a gradually decreasing number of revolutions per minute. One of the latter types made by MESSRS Urquhart, Lindsay & Co., Ltd., Dundee, is ill.u.s.trated in Fig. 29, and the mechanism displayed is identical with that employed for No. 4 method of preparing warps.

The V-shaped bank with its complement of spools (500 in our example) would occupy a position immediately to the left of Fig. 29. The threads would pa.s.s through a reed and then in a straight wide sheet between the pair of rollers, these parts being contained in the supplementary frame on the left. A similar frame appears on the extreme right of the figure, and this would be used in conjunction with another V-shaped bank, not shown, but which would occupy a position further to the right, i.e. if one bank was not large enough to hold the required number of spools. The part on the extreme right can be ignored at present.

The threads are arranged in exactly the same way as indicated in Fig.

28 from the bank to the reed in front of the rollers in Fig. 29, and on emerging from the pair of rollers are taken across the stretch between the supplementary frame and the main central frame, and attached to the weavers beam just below the pressing rollers. It may be advisable to have another reed just before the beam, so that the width occupied by the threads in the beam may be exactly the same as the width between the two f.l.a.n.g.es of the loom beam.

[Ill.u.s.tration: FIG. 29 WINDING-ON OR DRY BEAMING MACHINE _By permission of Messrs. Urquhart, Lindsay & Co. Ltd_.]

The speed of the threads is determined by the surface speed of the two rollers in the supplementary frame, the bottom roller being positively driven from the central part through the long horizontal shaft and a train of wheels caged in as shown. The loom beam, which is seen clearly immediately below the pressing rollers, is driven by friction because the surface speed of the yarn must be constant; hence, as the diameter over the yarn on the beam increases, the revolutions per minute of the beam must decrease, and a varying amount of slip takes place between the friction-discs and their flannels.

As the loom beam rotates, the threads are arranged in layers between the f.l.a.n.g.es of the loom beam. Thus, the 500 threads would be arranged side by side, perhaps for a width of 45 to 46 in., and bridging the gap between the f.l.a.n.g.es of the beam; the latter is thus, to all intents and purposes, a very large bobbin upon which 500 threads are wound at the same time, instead of one thread as in the ordinary but smaller bobbin or reel. It will be understood that in the latter case the same thread moves from side to side in order to bridge the gap, whereas in the former case each thread maintains a fixed position in the width.

The last and most important method of making a warp, No. 4 method, for the weaver is that where, in addition to the simultaneous processes of warping and beaming as exemplified in the last example, all the threads are coated with some suitable kind of starch or size immediately they reach the two rollers shown in the supplementary frame in Fig. 29. The moistened threads must, however, be dried before they reach the loom beam. When a warp is starched, dried and beamed simultaneously, it is said to be "dressed."

In the modern dressing machine, such as that ill.u.s.trated in Fig. 30, there are six steam-heated cylinders to dry the starched yarns before the latter reach the loom beams. Both banks, or rather part of both, can be seen in this view, from which some idea will be formed of the great length occupied. Several of the threads from the spools in the left bank are seen converging towards the back reed, then they pa.s.s between the two rollers--the bottom one of which is partially immersed in the starch trough--and forward to the second reed. After the sheet of threads leaves the second reed, it pa.s.ses partially round a small guide roller, then almost wholly round each of three cylinders arranged o, and finally on to the loom beam.

Each cylinder is 4 feet diameter, and three of them occupy a position between the left supplementary frame, and the central frame in Fig. 29, while the remaining three cylinders are similarly disposed between the central frame and the supplementary frame of the right in the same ill.u.s.tration.

The number of steam-heated cylinders, and their diameter, depend somewhat upon the type of yarn to be dressed, and upon the speed which it is desired to run the yarn. A common speed for ordinary-sized jute is from 18 to 22 yards per minute.

[Ill.u.s.tration: FIG. 30 A MODERN YARN DRESSING MACHINE WITH SIX STEAM-HEATED CYLINDERS]

A different way of arranging the cylinders is exemplified in Fig. 31.

This view, which ill.u.s.trates a machine made by Messrs. Charles Parker, Sons & Co., Dundee, has been introduced to show that if the warps under preparation contain a comparatively few threads, or if the banks are made larger than usual, two warps may be dressed at the same time. In such a case, three cylinders only would be used for each warp, and the arrangement would be equivalent to two single dressing machines. The two weaver's beams, with their pressing rollers, are shown plainly in the centre of the ill.u.s.tration. Some machines have four cylinders, others have six, while a few have eight.

A very similar machine to that ill.u.s.trated in Fig. 31 is made so that all the six cylinders may be used to dry yarns from two banks, and all the yarns wound on to one weaver's beam, or all the yarns may be wound on to one of the beams in the machine in Fig. 31 if the number of threads is too many for one bank.

[Ill.u.s.tration: FIG. 31 DRESSING MACHINE FOR PREPARING TWO WARPS SIMULTANEOUSLY _By permission of Messrs. Charles Parker, Sons & Co_.]

Suppose it is desired to make a warp of 700 threads instead of 500, as in the above example; then 350 spools would be placed in each of the two banks, the threads disposed as already described to use as much of the heating surface of the cylinder as possible, and one sheet of threads pa.s.sed partially round what is known as a measuring roller. Both sheets of threads unite into one sheet at the centre of the machine in Fig. 31, and pa.s.s in this form on to one of the loom beams.

It has already been stated that the lower roller in the starch box is positively driven by suitable mechanism from the central part of the machine, Fig. 29, while the upper roller, see Fig. 30, is a pressing roller and is covered with cloth, usually of a flannel type.

Between the two rollers the sheet of 350 threads pa.s.ses, becomes impregnated with the starch which is drawn up by the surface of the lower roller, and the superfluous quant.i.ty is squeezed out and returns to the trough, or joins that which is already moving upwards towards the nip of the rollers. The yarn emerges from the rollers and over the cylinders at a constant speed, which may be chosen to suit existing conditions, and it must also be wound on to the loom beam at the same rate. But since the diameter of the beam increases each revolution by approximately twice the diameter of the thread, it is necessary to drive the beam by some kind of differential motion.

The usual way in machines for dressing jute yarns is to drive the beam support and the beam by means of friction plates. A certain amount of slip is always taking place--the drive is designed for this purpose--and the friction plates are adjusted by the yarn dresser during the operation of dressing to enable them to draw forward the beam, and to slip in infinitesimal sections, so that the yarn is drawn forward continuously and at uniform speed.

During the operation, the measuring roller and its subsequent train of wheels and shafts indicates the length of yarn which has pa.s.sed over, also the number of "cuts" or "pieces" of any desired length; in addition, part of the measuring and marking mechanism uses an ink-pad to mark the yarn at the end of each cut, such mark to act as a guide for the weaver, and to indicate the length of warp which has been woven. Thus if the above warp were intended to be five cuts, each 120 yards, or 600 yards in all, the above apparatus would measure and indicate the yards and cuts, and would introduce a mark at intervals of 120 yards on some of the threads. And all this is done without stopping the machine. At the time of marking, or immediately before or after, just as desired, a bell is made to ring automatically so that the attendant is warned when the mark on the warp is about to approach the loom beam. This bell is shown in Fig.

29, near the right-hand curved outer surface of the central frame.

As in hand warping or in linking, a single-thread lease is made at the end of the desired length of warp, or else what is known as a pair of "clasp-rods" is arranged to grip the sheet of warp threads.

After the loom beam, with its length of warp, has been removed from the machine, the threads are either drawn through the eyes or mails of the cambs (termed gears, healds or heddles in other districts) and through the weaving reed, or else they are tied to the ends of the threads of the previous warp which, with the weft, has been woven into cloth. These latter threads are still intact in the cambs and reed in the loom.

CHAPTER XIV. TYING-ON, DRAWING-IN, AND WEAVING

If all the threads of the newly-dressed warp can be tied on to the ends of the warp which has been woven, it is only necessary, when the tying-on process is completed, to rotate the loom beam slowly, and simultaneously to draw forward the threads until all the knots have pa.s.sed through the cambs and the reed, and sufficiently far forward to be clear of the latter when it approaches its full forward, or beating up, position during the operation of weaving.

If, on the other hand, the threads of the newly-dressed, or newly-beamed, warp had to be drawn-in and reeded, these operations would be performed in the drawing-in and reeding department, and, when completed, the loom beam with its attached warp threads, cambs and reed, would be taken bodily to the loom where the "tenter,"

"tackler" or "tuner" adjusts all the parts preparatory to the actual operation of weaving. The latter work is often termed "gaiting a web."

There is a great similarity in many of the operations of weaving the simpler types of cloth, although there may be a considerable difference in the appearance of the cloths themselves. In nearly all the various branches of the textile industry the bulk of the work in the weaving departments of such branches consists of the manufacture of comparatively simple fabrics. Thus, in the jute industry, there are four distinct types of cloth which predominate over all others; these types are known respectively as hessian, bagging, tarpauling and sacking. In addition to these main types, there are several other simple types the structure of which is identical with one or other of the above four; while finally there are the more elaborate types of cloth which are embodied in the various structures of carpets and the like.

It is obviously impossible to discuss the various makes in a work of this kind; the commoner types are described in _Jute and Linen Weaving Calculations and Structure of Fabrics_; and the more elaborate ones, as well as several types of simple ones, appear in _Textile Design: Pure and Applied_, both by T. Woodhouse and T.

Milne.

Six distinct types of jute fabrics are ill.u.s.trated in Fig. 32. The technical characteristics of each are as follows--

[Ill.u.s.tration: FIG. 32 SIX DISTINCT KINDS OF TYPICAL JUTE FABRICS]

H.--An ordinary "HESSIAN" cloth made from comparatively fine single warp and single weft, and the threads interlaced in the simplest order, termed "plain weave." A wide range of cloths is made from the scrims or net-like fabrics to others more closely woven than that ill.u.s.trated.

B.--A "BAGGING" made from comparatively fine single warp arranged in pairs and then termed "double warp." The weft is thick, and the weave is also plain.

T.--A "TARPAULING" made from yarns similar to those in bagging, although there is a much wider range in the thickness of the weft.

It is a much finer cloth than the typical bagging, but otherwise the structures are identical.

S.--A striped "SACKING" made from comparatively fine warp yarns, usually double as in bagging, but occasionally single, with medium or thick weft interwoven in 3-leaf or 4-leaf twill order. The weaves are shown in Fig. 33.

C.--One type of "CARPET" cloth made exclusively from two-ply or two-fold coloured warp yarns, and thick black single weft yarns. The threads and picks are interwoven in two up, two down twill, directed to right and then to left, and thus forming a herring-bone pattern, or arrow-head pattern.

P.-An uncut pile fabric known as "BRUSSELLETTE." The figuring warp is composed of dyed and printed yarns mixed to form an indefinite pattern, and works in conjunction with a ground warp and weft. The weave is again plain, although the structure of the fabric is quite different from the other plain cloths ill.u.s.trated. The cloth is reversible, the two sides being similar structure but differing slightly in colour ornamentation.

As already indicated, there are several degrees of fineness or coa.r.s.eness in all the groups, particularly in the types marked H, B, T and S. The structure or weave in all varieties of any one group is constant and as stated.

All the weaves are ill.u.s.trated in the usual technical manner in Fig.

33, and the relation between the simplest of these weaves and the yarns of the cloth is ill.u.s.trated in Fig. 34. In Fig. 33, the unit weaves in A, B, C, D, E and F are shown in solid squares, while the repet.i.tions of the units in each case are represented by the dots.

[Ill.u.s.tration: FIG. 33 POINT-PAPER DESIGNS SHOWING WEAVERS FOR VARIOUS CLOTHS]

[Ill.u.s.tration: FIG. 34 DIAGRAMMATIC VIEWS OF THE STRUCTURE OF PLAIN CLOTH]

A is the plain weave, 16 units shown, and used for fabrics H and P, Fig. 32.

B is the double warp plain wave, 8 units shown, and shows the method of interlacing the yarns h patterns B and T, Fig. 32. When the warp is made double as indicated in weave _B_, the effect in the cloth can be produced by using the mechanical arrangements employed for weave _A_. Hence, the cloths _H_, _B_ and _T_ can be woven without any mechanical alteration in the loom.

_C_ is the 3-leaf double warp sacking weave and shows 4 units; since each pair of vertical rows of small squares consists of two identical single rows, they may be represented as at _D_. The actual structure of the cloth _S_ in Fig. 32 is represented on design paper at _C_, Fig. 33.

_D_ is the single warp 3-leaf sacking weave, 4 units shown, but the mechanical parts for weaving both _C_ and _D_ remain constant.

_E_ is the double warp 4-leaf sacking, 2 units shown, while

_F_ is the single warp 4-leaf sacking, 4 units shown.

The patterns or cloths for _E_ and _F_ are not ill.u.s.trated.