The Jute Industry: From Seed to Finished Cloth Part 3

1. The breaker card.

2. The finisher card.

The functions of the two machines are almost identical; indeed, one might say that the work of carding should be looked upon as one continuous operation.

The main difference between the two types of machines is in the method of feeding, and the degree of fineness or setting of the small tools or pins which perform the work. In both cases the action on the stricks of jute is equivalent to a combined combing and splitting movement, and the pins in the various rollers move relatively to each other so that while the pins of a slowly-moving roller allow the strick or stricks (because there are several side by side) to pa.s.s slowly and gradually from end to end, the pins of another but quickly-moving roller perform the splitting and the combing of the fibre. The pins of the slowly-moving roller hold, so to speak, the strick, while the pins of the quickly-moving roller comb out the fibres and split adhering parts asunder so as to make a comparatively fine division.

The conditioned stricks from the softening machine are first arranged in some suitable receptacle and within easy reach of the operative at the back or feed side of the breaker card. A receptacle, very similar to that used at the breaker card, appears near the far end of the softening machine in Fig. 13.

A modern breaker card is ill.u.s.trated in Fig. 14. The feed or back of the card is on the extreme right, the delivery or front of the card on the extreme left, while the gear side of the card is facing the observer. The protecting cages were removed so that the wheels would be seen as clearly as possible.

Some of the stricks of fibre are seen distinctly on the feed side of the figure; they are accommodated, as mentioned, in a channel-shaped stand on the far side of the inclined feed sheet, or feed cloth, which leads up to and conveys the stricks into the grip of the feeding apparatus. This particular type is termed a "sh.e.l.l" feed because the upper contour of the guiding feed bracket is shaped somewhat like a sh.e.l.l. There is a gradually decreasing and suitably-sized gap between the upper part of the sh.e.l.l and the pins of the feed roller.

The root ends of the pins in this roller lead, and the stricks of fibre are gripped between the pins and the sh.e.l.l, and simultaneously carried into the machine where they come into contact with the points of the pins in the rapidly-revolving large roller, termed a cylinder. The above-mentioned combing and splitting action takes place at this point as well as for a distance of, say, 24 inches to 30 inches below. The fibres which are separated at this stage are carried a little further round until they come into contact with the points of the pins in the above-mentioned slowly-moving roller, termed a "worker," and while the fibres are moving slowly forward under the restraining influence of the worker, they are further combed and split. A portion of the fibres is carried round by the pins of the worker from which such fibres are removed by the quicker moving pins of the second roller of the pair, termed a "stripper," and in turn these fibres are removed from the pins of the stripper by the much quicker moving pins of the cylinder.

[Ill.u.s.tration: FIG. 14 MODERN BREAKER CARD]

The above operations conducted by the first pair of rollers (worker and stripper) in conjunction with the cylinder, are repeated by a second and similar pair of rollers (worker and stripper), and ultimately the thin sheet of combed and split fibres comes into contact with the pins of the doffer from which it is removed by the drawing and pressing rollers. The sheet of fibres finally emerges from these rollers into the broad and upper part of the conductor. This conductor, made mostly of tin and V-shaped, is shown clearly on the left of the machine in Fig. 14. Immediately the thin film or sheet of fibres enters the conductor, it is caused as a body gradually to contract in width and, of course, to increase in thickness, and is simultaneously guided and delivered to the delivery rollers, and from these to the sliver can, distinctly seen immediately below the delivery rollers. The sliver is seen emerging from the above rollers and entering the sliver can.

The fibres in this machine are thus combed, split and drawn forward relatively to each other, in addition to being arranged more or less parallel to each other. The technical term "draft" is used to indicate the operation of causing the fibres to slip on each other, and in future we shall speak about this attenuation or drawing out of the fibres by this special term "draft."

It will be evident that, since the sliver is delivered into the can at the rate of about 50 yards per minute, this constant flow will soon provide a sufficient length of sliver to fill a sliver can, although the latter may hold approximately 20 lbs. The machine must, of course, deliver its quota to enable succeeding machines to be kept in practically constant work. As a matter of fact, the machines are arranged in what are termed "systems," so that this desirable condition of a constant and sufficient feed to all may be satisfactorily fulfilled.

The driving or pulley side of the breaker card is very similar to that shown in Fig. 15 which, however, actually represents the pulley side of one type of finisher card as made by Messrs. Douglas Fraser & Sons, Ltd., Arbroath. All finisher cards are fed by slivers which have been made as explained in connection with the breaker card, but there are two distinct methods of feeding the slivers, or rather of arranging the slivers at the feed side. In both cases, however, the full width of the card is fed by slivers laid side by side, with, however, a thin guide plate between each pair, and one at each extreme end.

One very common method of feeding is to place 10 or 12 full sliver cans--which have been prepared at the breaker card--on the floor and to the right of the machine ill.u.s.trated in Fig. 15. The sliver from each can is then placed into the corresponding sliver guide, and thus the full width of the machine is occupied. The slivers are guided by the sliver guides on to an endless cloth or "feed sheet"

which, in turn, conveys them continuously between the feed rollers.

The feed apparatus in such machines is invariably of the roller type, and sometimes it involves what is known as a "porcupine" roller. It will be understood that the feeding of level slivers is a different problem from that which necessitates the feeding of comparatively uneven stricks.

[Ill.u.s.tration: By permission of Messrs. Douglas Fraser & Sons, Ltd.

FIG. 15 FINISHER CARD WITH DRAWING-HEAD]

The slivers travel horizontally with the feed-sheet and enter the machine at a height of about 4 feet from the floor. They thus form, as it were, a sheet of fibrous material at the entrance, and this sheet of fibres comes in contact with the pins of the various pairs of rollers, the cylinder, and the doffer, in much the same way as already described in connection with the breaker card. There are, however, more pairs of rollers in the finisher card than there are in the breaker card, for while the latter is provided with two pairs of rollers, the former may be arranged with 3, 4, 5 or even 6 pairs of rollers (6 workers and 6 strippers). The number of pairs of rollers depends upon the degree of work required, and upon the opinions of the various managers.

There are two distinct types of finisher cards, viz--

1. Half-circular finisher cards.

2. Full-circular finisher cards.

The machine ill.u.s.trated in Fig. 15 is of the latter type, and such machines are so-called because the various pairs of rollers are so disposed around the cylinder that they occupy almost a complete circle, and the fibre under treatment must move from pair to pair to undergo the combing and splitting action before coming into contact with the doffer. There are five pairs of rollers in the machine in Fig. 15, and all the rollers are securely boxed in, and the wheels fenced. The arrangement of the wheels on the gear side is very similar to that shown in connection with the breaker card in Fig. 14, and therefore requires no further mention. Outside the boxing comes the covers, shown clearly at the back of the machine in Fig. 15, and adapted to be easily and quickly opened when it is desired to examine the rollers and other parts.

The slivers, after having pa.s.sed amongst the pins of the various rollers, and been subjected to the required degree of draft, are ultimately doffed as a thin film of fibres from the pins of the cylinder and pa.s.s between the drawing rollers to the conductor. The conductor of a finisher card is made in two widths, so that half the width of the film enters one section and the other half enters the other section. These two parallel sheets, split from one common sheet, traverse the two conductors and are ultimately delivered as two slivers about 6 inches above the point or plane in which the 10 or 12 slivers entered, and on to what is termed a "sliver plate." The two slivers are then guided by horns projecting from the upper surface of the sliver plate, made to travel at right angles to the direction of delivery from the mouths of the conductors, and then united to pa.s.s as a single sliver between a pair of delivery rollers on the left of the feed and delivery side and finally into a sliver can.

In special types of finis.h.i.+ng cards, an extra piece of mechanism--termed a draw-head--is employed. The machine ill.u.s.trated in Fig. 15 is provided with this extra mechanism which is supported by the small supplementary frame on the extreme right. This special mechanism is termed a "Patent Push Bar Drawing Head," and the function which it performs will be described shortly; in the meantime it is sufficient to say that it is used only when the slivers from the finisher card require extra or special treatment. A very desirable condition in connection with the combination of a finisher card and a draw-head is that the two distinct parts should work in unison. In the machine under consideration, the feed and delivery rollers of the card stop simultaneously with the stoppage of the draw-head mechanism.

One of the chief aims in spinning is that of producing a uniform thread; uniform not only in section, but in all other respects. A so-called level thread refers, in general, to a uniform diameter, but there are other equally, if not more, important phases connected with the full sense of the word uniform.

It has already been stated that in the batching department various qualities of jute are mixed as judiciously as possible in order to obtain a satisfactory mixture. Fibres of different grades and marks vary in strength, colour, cleanness, diameter, length and suppleness; it is of the utmost importance that these fibres of diverse qualities should be distributed as early as possible in the process so as to facilitate the subsequent operations.

[Ill.u.s.tration: _By permission of Messrs. James F. Low & Co., Ltd. _ FIG. 16 WASTE TEAZER]

However skilfully the work of mixing the stricks is performed in the batching department, the degree of uniformity leaves something to be desired; further improvement is still desirable and indeed necessary.

It need hardly be said, however, that the extent of the improvement, and the general final result, are influenced greatly by the care which is exercised in the preliminary processes.

The very fact of uniting 10 or 12 slivers at the feed of the finisher card mixes 10 or 12 distinct lengths into another new length, and, in addition, separates in some measure the fibres of each individual sliver. It must not be taken for granted that the new length of sliver is identical with each of the individual lengths and ten or twelve times as bulky. A process of drafting takes place in the finisher card, so that the fibres which compose the combined 10 or 12 slivers shall be drawn out to a draft of 8 to 16 or even more; this means that for every yard of the group of slivers which pa.s.ses into the machine there is drawn out a length of 8 to 16 yards or whatever the draft happens to be. The resulting sliver will therefore be approximately two-thirds the bulk of each of the original individual slivers. The actual ratio between them will obviously depend upon the actual draft which is imparted to the material by the relative velocities of the feed and delivery rollers.

It is only natural to expect that a certain amount of the fibrous material will escape from the rollers; this forms what is known as card waste. And in all subsequent machines there is produced, in spite of all care, a percentage of the amount fed into the machine which is not delivered as perfect material. All this waste from various sources, e.g. thread waste, rove waste, card waste, ropes, dust-shaker waste, etc., is ultimately utilized to produce sliver for heavy sacking weft.

The dust-shaker, as its name implies, separates the dust from the valuable fibrous material, and finally all the waste products are pa.s.sed through a waste teazer such as that made by Messrs. J. F. Low & Co., Ltd., Monifieth, and ill.u.s.trated in Fig. 16. The resulting ma.s.s is then re-carded, perhaps along with other more valuable material, and made into a sliver which is used, as stated above, in the production of a cheap and comparatively thick weft such as that used for sacking.

CHAPTER VIII. DRAWING AND DRAWING FRAMES

The operations of combing and splitting as performed in both the breaker and finisher card are obviously due to the circular movement of the pins since all these (with the single exception of those in the draw-head mechanism of certain finisher cards) are carried on the peripheries of rotating rollers. In the draw-head mechanism, the pins move, while in contact with the fibres, in a rectilinear or straight path. In the machines which fall to be discussed in this chapter, viz., the "drawing frames," the action of the pins on the slivers from the finisher card is also in a straight path; as a matter of fact, the draw-head of a finisher card is really a small drawing frame, as its name implies. Moreover, each row or rather double row, of pins is carried separately by what is termed a "faller." The faller as a whole consists of three parts:

1. A long iron or steel rod with provision for being moved in a closed circuit.

2. Pour or six bra.s.s plates, termed "gills" or "stocks," fixed to the rod.

3. A series of short pins (one row sometimes about 1/8 in. shorter than the second row), termed gill or hackle pins, and set perpendicularly in the above gills.

The numbers of fallers used is determined partly by the particular method of operating the fallers, but mostly by the length of the fibre. The gill pins in the fallers are used to restrain the movements of the fibres between two important pairs of rollers.

There are actually about four sets of rollers from front to back of a drawing frame; one set of three rollers const.i.tute the "retaining"

rollers; then comes the drawing roller and its large pressing roller; immediately after this pair is the "slicking" rollers, and the last pair is the delivery rollers. The delivery rollers of one type of drawing frame, called the "push-bar" drawing frame, and made by Messsrs. Douglas Fraser & Sons, Ltd., Arbroath, are seen distinctly in Fig. 17, and the can or cans into which the slivers are ultimately delivered are placed immediately below one or more sections of these rollers and in the foreground of the ill.u.s.tration.

The large pressing rollers, which are in contact with the drawing roller, occupy the highest position in the machine and near the centre of same. Between these rollers and the retaining rollers are situated the above-mentioned fallers with their complements of gill pins, forming, so to speak, a field of pins.

Each sliver, and there maybe from four to eight or more in a set, is led from its sliver can at the far side of the machine to the sliver guide and between the retaining rollers. Immediately the slivers leave the retaining rollers they are penetrated by the gill pins of a faller which is rising from the lower part of its circuit to the upper and active position. Each short length of slivers is penetrated by the pins of a rising faller, these coming up successively as the preceding one moves along at approximately the same surface speed as that of the retaining rollers. The sheet of pins and their fallers are thus continuously moving towards the drawing rollers and supporting the slivers at the same time. As each faller in succession approaches close to the drawing rollers, it is made to descend so that the pins may leave the fibres, and from this point the faller moves backwards towards the retaining roller until it reaches the other end ready to rise again in contact with the fibres and to repeat the cycle as just described. It will thus be seen that the upper set of fallers occupy the full stretch between the retaining rollers and the drawing rollers, but there is always one faller leaving the upper set at the front and another joining the set at the back.

[Ill.u.s.tration: Fig. 17 Push-bar drawing frame]

The actual distance between the retaining rollers and the drawing rollers is determined by the length of the fibre, and must in all cases be a little greater than the longest fibre. This condition is necessary because the surface speed of the drawing roller is much greater than that of the retaining rollers; indeed, the difference between the surface speeds of the two pairs of rollers is the actual draft.

Between the retaining and drawing rollers the slivers are embedded in the gill pins of the fallers, and these move forward, as mentioned, to support the stretch of slivers and to carry the latter to the nip of the drawing rollers. Immediately the forward ends of the fibres are nipped between the quickly-moving drawing rollers, the fibres affected slide on those which have not yet reached the drawing rollers, and, incidentally, help to parallelize the fibres. It will be clear that if any fibre happened to be in the grip of the two pairs of rollers having different surface speeds, such fibre would be snapped. It is to avoid this rupture of fibres that the distance between the two sets of rollers is greater than the longest fibres under treatment. The technical word for this distance is "reach."

On emerging from the drawing rollers, the combed slivers pa.s.s between slicking rollers, and then approach the sliver plate which bridges the gap between the slicking rollers and the delivery rollers, and by means of which plate two or more individual slivers are diverted at right angles, first to join each other, and then again diverted at right angles to join another sliver which pa.s.ses straight from the drawing rollers and over the sliver plate to the guide of the delivery rollers. It will thus be seen that a number of slivers, each having been drawn out according to the degree of draft, are ultimately joined to pa.s.s through a common sliver guide or conductor to the nip of the delivery rollers, and thence into a sliver can.

The push-bar drawing ill.u.s.trated in Fig. 17, or some other of the same type, is often used as the first drawing frame in a set. With the exception of the driving pulleys, all the gear wheels are at the far end of the frame, and totally enclosed in dust-proof casing. The set-on handles, for moving the belt from the loose pulley to the fast pulley, or _vice versa_, are conveniently situated, as shown, and in a place which is calculated to offer the least obstruction to the operative. The machines are made with what are known as "two heads" or "three heads." It will be seen from the large pressing rollers that there are two pairs; hence the machine is a "two-head" drawing frame.

The slivers from the first drawing frame are now subjected to a further process of doubling and drafting in a very similar machine termed the second drawing frame. The pins in the gills for this frame are rather finer and more closely set than those in the first drawing frame, but otherwise the active parts of the machines, and the operations conducted therein, are practically identical, and therefore need no further description. It should be mentioned, however, that there are different types of drawing frames, and their designation is invariably due to the particular manner in which the fallers are operated while traversing the closed circuit. The names of other drawing frames appear below.

Spiral or screw gill; Open link chain; Rotary; Ring Carrier Circular.

For the preparation of slivers for some cla.s.ses of yarn it is considered desirable to extend the drawing and doubling operation in a third drawing frame; as a rule, however, two frames are considered sufficient for most cla.s.ses of ordinary yarn.