The jute industry · Chapter 19FIG. 16 WASTE TEAZER By permission of Messrs. James F. Low & Co., Ltd
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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 passes 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 passed through a waste teazer such as that made by Messrs. J. F. Low & Co., Ltd., Monifieth, and illustrated in Fig. 16. The resulting mass 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.
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 brass 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 constitute 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 illustration. 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.