Fig. 2.—Individual Rubber Warp Let-Off Motion
When we remember that the front reed will pass by the rubber threads possibly six or seven hundred times from their entrance into the shed to their reaching the leaving line, it is not to be wondered at that chafing is liable to take place. With all this liability of spoiling goods it becomes readily apparent that any device employed to regulate such an important feature as the tension of the rubber warps must be very sensitive and dependable.
On looms making wide goods, and where space will allow, regulation is accomplished by a worm and gear movement as shown in Fig. 2. The iron rubber beam is threaded on to a square shaft A, at one end of which a gear wheel B is fastened. In this gear is meshed the worm C, which is operated by a heavy linen cord D passed twice around a pulley E. The cord derives its movement from a rocking shaft F, on which there is fastened a screw extension G, by which adjustment can be made so as to deliver very accurately any amount from the rubber beam.
With this kind of movement, and in order to feed the thread uniformly into the web, it becomes necessary to use mechanically made warps where the same uniformity has been maintained in putting the warps on the beams. The warps so made must come from the thread manufacturer in individual warps, which are done up in chain form, each warp containing the requisite number of threads.
Making Rubber Warps
The machine used for making the warps, shown at Fig. 3, is mounted on an iron frame A, which carries the power driven warp beam B. Behind this is an open top expansion reed C, the dents of which are regulated to open, coarse or fine by an internal spring which is regulated by a hand wheel. This reed also has a screw sidewise adjustment for centering. Behind the reed C are fixed two pairs of nip rolls, D and E, and an open roller F, which is followed by a belt-driven beater roll G, used to beat the threads out straight as they leave the chain.
The rubber warp is first laid on a cloth on the floor, under the beater roll. The end is then passed over the beater roll G, over the open roll F, through the two pairs of nip rolls D and E, over the expansion reed C, and then looped to a leader on the rubber beam, where the knot is put in a counter-sink on the beam barrel, so as not to interfere with the lay of the warp. The section of the warp between the two pairs of nip rolls is brought down in loop form, shown at H, and the nip rolls are then closed while the warp is in this position. The two sets of nip rolls are speeded alike and the rubber is always kept slack between the gripping points, so that all threads passing through the last set of nip rolls, D, are perfectly gauged in length and tension when passing through the reed C and on to the beam B. The threads of rubber are under considerable tension, inasmuch as the beam B is driven faster than the nip rolls D and E.
Friction Let-Off
Where there is limited loom space, and where a small number of threads are employed, as in the narrower garter fabrics, it is not as practical to have the warps made mechanically, and for this reason they are not likely to be put on the beams with as much uniformity of tension. In such cases it becomes necessary to have some automatic device that will correct any irregularities and maintain a uniform delivery throughout. The device for doing this is shown at Fig. 4.
The warp carrier A is fastened to the back rail, which carries the warp, over which is passed the friction cloth G which is hung from a rod D. The friction cloth is fastened at the bottom to the graduated warp lever E, which is bolted to the bottom rail H, as shown. The rubber threads constituting the warp pass in a direct line to the harness C, and then to the breast beam B. The lever E, and the weights F, allow for proper adjustment of the friction cloth so as to keep the lever level as the warp beam empties.