Cotton Weaving and Designing / 6th Edition

by John T. Taylor

SECTIONAL WARPING.

Sectional warping is a system chiefly employed in the production of coloured striped warps, from yarn previously dyed and sized in the hank, and subsequently wound upon warpers’ bobbins by a drum-winding machine. It is also sometimes employed in the production of grey warps for ball sizing. As its name implies, the operation consists of preparing a warp in sections, termed “cheeses,” each of which is a complete unit, and virtually a transverse section, of the full warp. When the required number of sections for a warp have been made, they are compressed between flanges side by side upon a mandril of a running-off machine, and their yarn run from them simultaneously on to a weaver’s beam. Sometimes a sectional warper works in conjunction with an automatic stop-motion similar to that of a beam warping machine, in which case bobbins are contained in a V-shaped creel. They also sometimes work without a stop-motion. In that case bobbins are contained in a curved creel similar to that employed in conjunction with a warping mill, whereby the threads are better under the observation of the operative warper, and broken threads may be more readily detected. One of the most important considerations in sectional warping is the production of sections of uniform diameter and length of yarn; otherwise, warp-ends would be of varying degrees of tension; also, waste of material would result from irregular lengths of yarn on the sections.

FIG. 17.

The principal parts of a well-known type of sectional warping machine are shown in Figs. [17], [18], and [19]. Warp-ends, A, are withdrawn from a curved creel, and passed separately through needle eyes of a leasing heck, B, thence through a V-reed, D, over a tin measuring roller, F, and on to a section block, O, which is compressed between two flanges, N, O, upon a shaft, Q, by which it is turned. Flange N is removable to permit of a full section being replaced by an empty one. Another flange, 24, is keyed upon the section shaft, Q, and driven by means of friction bowls, 20, 20’, placed one on each side, and turned by driving shafts 16, 16′, each of which contains a wide loose pulley, 17, 17′, a narrow fast pulley, 18, 18′, and a toothed wheel, 15, 15′, which are in gear. Thus, if driving strap 19 is placed in a central position (as indicated) it runs on both loose pulleys, without effect; but if placed upon the fast pulley 18, it will turn the section forward, and wind yarn on the front, as shown, and if placed on fast pulley 18′, it will turn a section backward, and wind yarn at the back. This arrangement enables sections to be made with one-half of a full repeat of a warp pattern, either alone or in addition to several repeats (provided the pattern is a symmetrical one), so that when all sections are placed in their proper position for running their yarn on to a weaver’s beam, two halves of a pattern will join together without a break. A uniform rate of winding yarn is maintained by causing friction driving bowls, 20, 20′, to automatically recede from the section shaft at a pace exactly corresponding to that at which a section increases in diameter, thereby gradually retarding the velocity of the section shaft.

FIG. 18.

FIG. 19.

A presser roller, 12, carried at the end of a lever, 9, 11, fulcrumed on shaft 10, bears against yarn during winding, to wind it more compactly, and also to ensure uniformity of diameter of sections composing the same warp. During the winding of the first or “trial” section, the presser, which is suitably weighted, is free to recede at such pace as corresponds with the increasing diameter of that section; but for subsequent sections, the presser is under mechanical control, and may only recede at a prescribed pace, which should, however, exactly coincide with its recession during the formation of the first section. The movement of the presser is governed by means of a toothed quadrant or sector, 1, communicating with presser lever, 9, by a connecting rod, 6. The position of rod 6, in relation to the fulcrum 2 of the sector and the fulcrum 10 of the presser lever, determines the velocity at which the presser recedes. A cam, P, on the end of section shaft Q, imparts an intermittent rotary motion to a short vertical shaft, Y, by means of lever S, U, and pawl W. Surmounting shaft Y is a worm, Z, gearing with the teeth of sector 1 which slowly rises as a section revolves, thereby causing the presser to recede, at a prescribed pace. The number of revolutions of the section shaft is indicated upon a dial; also, the length of yarn wound is indicated upon a dial, by fingers operated by a train of wheels driven from worm G, on the end of tin measuring roller shaft F. The two indicators, therefore, serve as a check upon each other.

FIG. 20.

FIG. 21.

Section blocks are made in different widths from 3½ inches upwards. Some are constructed so as to permit of expansion and contraction, as shown in [Fig. 20]. Pressers are also constructed on a similar principle, as shown in [Fig. 21].