Chapter X: Spinning

The final machine used in the conversion of rove to the size of yarn required is termed the spinning frame. The actual process of spinning is performed in this machine, and, although the whole routine of the conversion of fibre into yarn often goes under the name of spinning, it is obvious that a considerable number of processes are involved, and an immense amount of work has to be done before the actual process of spinning is attempted. The nomenclature is due to custom dating back to prehistoric times when the conversion of fibre to yarn was conducted by much simpler apparatus than it is at present; the established name to denote this conversion of fibre to yarn now refers only to one of a large number of important processes, each one of which is as important and necessary as the actual operation of spinning.

A photographical reproduction of a large spinning flat in one of the Indian jute mills appears in Fig. 20, showing particularly the wide "pass" between two long rows of spinning frames, and the method adopted of driving all the frames from a long line shaft. Spinning frames are usually double-sided, and each side may contain any practicable number of spindles; 64 to 80 spindles per side are common numbers.

The rove bobbins, several of which are clearly seen in Fig. 20, are brought from the roving frame and placed on the iron pegs of a creel (often called a hake) near the top of the spinning frame-actually above all moving parts of the machine. Each rove bobbin is free to rotate on its own peg as the rove from it is drawn downwards by the retaining rollers. The final drafting of the material takes place in this frame, and a considerable amount of twist is imparted to the drawn out material; the latter, now in the desired form and size of yarn, is wound simultaneously on to a suitable size and form of spinning bobbin.

When the rove emerges from the retaining rollers it is passed over a "breast-plate," and then is entered into the wide part of the conductor; it then leaves by the narrow part of the conductor by means of which part the rove is guided to the nip of the drawing rollers, The rove is, of course, drafted or drawn out between the retaining and drawing rollers according to the draft required, and the fibrous material, now in thread size is placed in a slot of the "thread-plate," then round the top of the flyer, round one of the arms of the flyer, through the eye or palm at the end of the flyer arm and on to the spinning bobbin. The latter is raised and lowered as in the roving frame by a builder motion, so that the yarn may be distributed over the full range between the ends or flanges.

Each spindle is driven separately by means of a tape or band which passes partially round the driving cylinder and the driven whorl of the spindle, and a constant relation obtains between the delivery of the yarn and the speed of the spindle during the operation of spinning any fixed count or type of yarn. In this connection, the parts resemble those in the roving frame, but from this point the functions of the two frames differ. The yarn has certainly to be wound upon the bobbin and at the same rate as it is delivered from the drawing or delivery rollers, but in the spinning frame the bobbin, which rotates on the spindle, is not driven positively, as in the roving frame, by wheel gearing; each spinning bobbin is actually driven by the yarn being pulled round by the arm of the flyer and just sufficient resistance is offered by the pressure or tension of the "temper band" and weight. The temper band is simply a piece of leather or hemp twine to which is attached a weight, and the other end of the leather or twine is attached to the builder rail.

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.