US2398756A - Textile drawing frame - Google Patents

Description

Patented Apr. 16, 1946 scarse` `l 'rarer-11,12"piuminoFrattini"j,` f

Roderc `D. Tarr, Biddeford, Maine,l assignor to Saco-Lowell Shops, Boston, Mass., a. corporation I of Maine y `Appucatium May 25, 1941i,serial-15m.` 483,331 l [j ly connus. (cris-130)? ffl'his'invention relates to drawing frames `of the `type commonly used in the manufacture of` cotton Iyarnl "inf doubling "and drawing strands of f roving or. sliver.l AForexample, `it is a`common practice to double founsix` or'eight strands of card sliver lor roving and to draft them in a drawing frame to produce a single roving which will be*v more uniform in compositionthan were'any of the constituent strands from which it was made. Often this doubling and drawing operation is repeated l one or more times before the resulting roving is taken to th'e next step inthe customary process `of manufacturing -cotton yarn.

A These drawing frames'comprise a series of pairs of intermeshing uted rolls; positioned one in advance of another, through which the web com- `posed of the rovings is "fed, each successive pair vof rollsbeing driven at a slightly higher peripheral speed than the preceding pair so as to produce the desired draft. The web issuing from be-V tween the delivery rolls is gathered and led into a coiler.

In order for such a machine to function properly, the iiuted rolls must be manufactured with a high degree of accuracy. This necessarily increases materially the expense of manufacture of the machine. That such accuracy is necessary will be evident from the consideration that th'e effect of inaccuracy is cumulative as the machine operates. That is, if, due to such inaccuracies, one pair of rolls feeds at, say, one thousandth of an inch slower per revolution at one end than at the other, then at the end of one thousand revolutions the error will amount to a length of one inch. While as slight an error as this `will be lost in the draft, a somewhat larger error Vmay well result, in the course of a few hours run,

in producing a sag in the web between two successive pairs of rolls, thus nullifying the drafting operation at this point. In any event, such errors tend to defeat the object of the doubling and drawing process, which ls to produce a strand having greater uniformity than do the original strands.

The present invention deals especially with these considerations, and it aims to devise a drawing frame in which'the desired degree of accuracy canbe obtained more economically and with more certainty.

The nature of the invention will be readily understood from the following description when read in connection withthe accompanying drawing, and th'e novel features will be particularly pointed out in the appended claims. n

In the drawing,

Figure 1 is a vertical,4 sectional viewof a' head vof a drawing framewith `some partsshown in elevation; and

` FigureZ is annlalfgd sectional view of cooperating portionsofone pairof therolls illustratedin'Fig. 1. `Referring rstto Fig.` 1, the constructionthere shown` comprises four pairs of metallic intermeshingrolls including bottom rolls 2, `3, 4 and 5 and top rolls cooperating with the respective bottom'rolls and indicated at 6, 1, Band 9. The bottom rolls are positively driven byhgearing but the top rolls are driven simply through "their relationship to the `botto`m"rlls` and through the interveningflber 'or gristfy Weight hooks |0, Il,

l2 and I3b`ear` on the gudgeons ofthe respective top rolls andj are of suchmass as to makeeach.`

pair of rolls grip the web of lbersWith-sumcient pressure for operatingpurposes. Each successive pair of rolls,\proceeding` from right to' left, is driven at a suiciently higher speed than the preceding pair to produce thedesired draft. The arrangement shown also includesV the usual hinged top cover I8 equipped with a clearer cloth i9.

So far as the general organization of the construction Just described is concerned, itmay be exactly like those in common use, and it may be equipped with the usual guides, stop devices, and

oth'eraccessories ordinarily used in drawing` frames. A customary arrangement is to draw the strands of roving or sliver from supply cans set up at the right-hand side of the machine, to feed them together in the form ofa web W through the rolls, and then to guide the reduced web issuing from the front'or delivery rolls 2 and 6 into the trumpet of a coller which deposits the drawn strand in a roving canr In some cases, also. one or more of the top rolls 6 and 1 are replaced with smooth surfaced cushioned covered rolls, and in some machines, also, the number of rolls is increased. Such changes or modifications are im-` material from the standpoint of the present invention. f

According to this invention one or more of these pairs of rolls are fluted in the manner indicated od, to produce ribs a of `the form there shown,

and these ribs arev separated by intervening round-bottomed grooves b. After the iluting operations have been oompletedthe rollis ground very accurately to a given outside diameter, the

tolerance from oneend to another of the roll being preferably within two-thousandths of an inch. 'I'his grinding operation produces small attened tips c on the rounded ends of the ribs a.

The top roll 9 is also milled, as shown in Fig. 2, to produce round-ended ribs d which are shorter in radial dimensions than the ribs a of the bottom roll, and these ribs d are separated by roundbottomed grooves e like the grooves b. The utes in both rolls have the same pitch. In making the top roll, however, no eifort is made to obtain extraordinary accuracy in either its inside or outside diameter, but the depth of ilute is maintained with a high degree of accuracy. In other words, the depth of flute is constant from one end to the other, and this result may be readily produced by making the same milling cutter which shapes a rib also form the bottom`A of the adjoining groove simultaneously. Also, the radius of curvature of the grooves is somewhat, say four or ve-thousandths, larger in the top roll than in the bottom roll. The construction shown in Fig. 2 is drawn substantially to scale and is enlarged on a twenty to one ratio.

The important feature vof this arrangement is that the bottom roll hasa constant outside diam eter from end to end of the fiber working area thereof, while the top roll has a constant depth of ute throughout its ber working area irrespective of minor manufacturing errors in diameter. Consequently, and because the lower roll is positively driven, and also because a substantial clearance of something in thev order of ten to fourteen-thousandths of an inch is provided between the ilutes of the top roll and the Walls of the grooves of the .bottom roll, the latter roll controls the rate of feed of the brous web irrespective of the diameter of the top roll. With this construction, therefore, the rolls 9 and 5 will produce a 4uniform delivery or rate of feed of `sliver across their entire ber. engaging surfaces. And this result is produced bythe presence of cooperating features of accuracy in the two rolls which are easily produced by relatively inexpensive manufacturing operations.

All, or any desired number, of the pairs of rolls in a drawing frame may be made in this manner. Accordingly. the invention makes it possible to obtain, in a more advantageous manner, those results which have only been obtained heretofore in a drawing frame by the use of manufacturing processes considerably more expensive than those required in making the rolls above described.

Having thus described my invention, what I desire to claim as new is:

1. In a textile drawing frame, comprising a series of pairs of drafting rolls, mounted one behind another, to operate successively on a web composed of parallel 'rovings, certain at least of said pairs of rolls consisting of driven lower metallic luted rolls and upper metallic fluted rolls, each meshing with and resting upon its respective cooperating lower roll and being driven thereby, a construction in which the outside diameter of one at least of said lower rolls is maintained with a high degree of accuracy throughout its fiber working area notwithstanding normal manufacturing variations in the depths of its flutes, and

its cooperating top roll has a constant depth of ute throughout vits ber Working area regardless of minor variations in its diameter, the two rolls having the same vpitch of fiuting and being supported in a meshing relationship but the ribs of the Vtop roll being of smaller radial height than -those of the bottom roll and having an abnormal- 1y large clearance with the walls of the grooves of the lower roll even when the ribs of the lower roll substantially contact with the bottoms of the grooves in the top roll.

2. In a drawing frame according to preceding claim l, a construction in which said ribs of the lower roll have rounded ends with narrow flattened tops. t

RODERIC D. TARR.

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