US2369893A - Cotton carding mechanism - Google Patents

Description

Feb. 20, 1945. v c, GWALTNEY 2,369,893

' COTTON CARDING MECHANISM Filed Aug. 21, 1942 Patented Feb 20,1945

tol'sa'coeLowe'll fIShops, Boston,

j ration of Maine Mass, a corpo- Apiilication Augustt21,'1942,-Serial Nat-55,555

' i (or. 19-98) v v :2 Claims. -"One of the objects of a cotton carding operatiort is toseparate the ionger cotton staple from the war short 'fibers and foreign 'm'aterials still retained' by it. A veryconsiderablepart OithiS function is performed at the I lower "side of the card :cylinder "Where it passes -over' the II card screen i or 'grid. I Usually this screen consists of a combination of barsand solid met'al fas'te'ned to suitabl'e'supports in such a manner I that -the' spacing of-successive portions-of the screen-"from the peripheralsurface-0f thecylincler or, -'more accurately; from the face of the card "clothing,

can-"be adjusted with a high degree of 1 accuracyand 'precision. Just what occurs-at thisscreen is I not altogether clear, notwithstanding the -fact that these machineshave been I in common use for many years. This-iseVidencedby theob servation that the amount-of waste separated from the-good fiberand*collected daily under a l-ineof- "cards operating on the;- same stock and presumably setto givejas uniform results as possible -wfll :vary to such a degree that it is not I reasonable" tobelieve that the difference; inadjac'e'nt'machines is'due solelyto variations in'the sto'okflthas' been believed that variations in air pressures at different points between";v the cylinder and the screen, or peculiarities -of air currents-in" thisregiom areresponsible for much of thewariationin results. But whatever maybe the cause. the fact of very substantial non-uni formity' in results produced-by difierent cards is I wellzknown. I

The materials causing the most trouble' are the short z'fuzzy fibersadhering to the cotton seed, part :of which is removed during the ginning operation sand :therefore goes along with the longerfflber. '.This;:;material; :whenseparated, is kHOWIIKiaS'"l1int8IS,5flIIdf itiis extremely troublesome: 1117 various preparatory-l. operations prior to :becauseithe: fiberstareasowshort that they cannot ;bezzcontrolled.;.asccan the rlonger fibers,

I they. tend ;tof-;-bunch,i toczad'here'. to" the .good'. fiber,

and. theyeare important factors. in contributing to the. irregularity; or moneuniformity 'of spun'yarn. fiA further dimculty experienced in using some "The mature of :the- "invention will be readily understood from the following description when read in connection withtthe accompanying .jdrawinggand .thernovelrfeatures will be particularlypointed out in the appended "claims.

In the drawing, I Figure 1i isva -vertical, sectional view ofa card cylinder and adjacent parts vat right angles to 'thetraxis' of:the cylinder and shows it equipped with :a :screen :plate made in accordance with this. invention; I I :EigxZ is .a plan-view of. aportion ofthescreen plateshowminFigplyand Fig. I 3 "is a :plan viewon a smallisectionrof the'screempIate. I

.In the. construction :shown .in' the drawing a cardcylin'der. of awcommon commercial .form .is

7 indicated at 2,; associated in the usual waywith a licker-in3 and'a :dofier 4. jMounted-below thecylinder, :and inathe usual cooperative-relationship thereto, is a-screen consisting of =a perforatedysmooth surfaced, metalplate. Preferably the'perforations are in the. formzof slots B exten'ding rat right angles to the direction o'f the :movement of 'IfibBI'TfiiClOSS them; and spaced apart gbyl'relatively small and substantially uni form dimensions, the :entire screening isurface of the'platetbeing made in'rthiss-way. Assshown I in Figs- 2' and '3, :theseislotsrare arranged incircumferenti'al rowsazand adjacent rows are" spaced slightly apart, thus leaving-circumferential"strips of'unbrokenrmetal extending'the' entire length I of the screen. If desiredghowever, the slots-may oftheteommercialxtypes ofwscreens and one which lends weight to the ivariation in air pressure theory aboveireferredito, is that much good fiber hasa-been. found. in theseimachines :to :blow out under :the licker+in, .thus making it necessary tossetl. thezmote knife; notiatv its. poihthofig'reatest I efliciency as re. n=cleaning zelement but,v instead,- in such a position as to preventuthezgoodstockffrom blowing-out.

Hheu .presentiinvention. is :especially concerned with-theftoregoinQfactors; and it aims to improve cardswith aaviewzto maintainingmorernniform and better: control-10ftthezconditions; ati' the lower side of the card cylinder,'l.;andrto=producing a more effective separation of linters and other shortffibersfirom Ith K longer fibers. I

be;staggered:orzecheloned' so that one slot overlapszone :orfmoreadjacent slots .circumferentially. As. shown,.the.individual.slots? in each row "are offset or staggered with reference to those in ca nextacljacentrow.

A plate -made in this may from cold rolle steel, or any other suitablemetal of adequate;

gage to be= stable, may be supported. in any common or suitable-mannergso that its clearance with the peripheral surface of the'cylinder can be accurately adjusted. Usually this clearance is made. relatively large; saythree-esixteenths. of an inch, at'the frontend 'ofithescreennear the: dofien an'd it .decreasesgra'dually to arelatively small .value, say in the neighborhood of twenty five'or thirty thousandths of an inch near the lickerein. Inother words,.no change inthe usual mounting or adjustment of thescreen'is requiredcbythis invention. I I

It-"has been found in using a screen of this character" that it produces exceptionally favorable results, particularly 1 in that there" is a better separationof *the linters and-other short fibers from the good' fiber, the waste'taken out by adlarger scale of a as to the excessive discharge of air under the licker-in above mentioned. The reason for this improved result apparently is that because the screen is perforated substantially throughout its area, there is no opportunity for any substantial pressure to build up at localized areas between the screen and the cylinder. In other words, the pressure conditions maintained between these parts appear to be substantially uniform. In any event, whatever the reason may be, the difficulty formerly experienced with excessive draft near the forward end of the screen and the resultant loss of good fiber at this point is no longer troublesome.

I have also discovered that if one or both surfaces of this plate are coated with a paint or varnish having good electrical insulating properties, a further and very noticeable improvement in results is realized.

The exact reasons for this improvement are very difiicult to ascertain with certainty. The best explanation that I am able to give at this time for this result is that a card naturally tends to create static electricity. Its very organization contributes to this end and it is well known that unless measures are taken to control such generation of static it can be an exceedinglytroublesome factor. It will be observed that the plate 5 when coated, as above described, acts as an electrical condenser. A static charge is created in this plate during the normal operation of the machine, and such charge naturally causes, I believe, the short fibers to stand out tangentially at the surface of the cylinder. There is, also, a very considerable centrifugal force tending to throw them oif the cylinder altogether. As the short fibers stand on end and are swept over the Most of the fibers which it is desired to eliminate are less than three-eighths of an inch in length and these are effectually discharged if the slots are made about three-sixteenths of an inch in Width.

A typical length of slot is three-quarters of an inch, but the latter dimension is far less important from the standpoint of the carding action than is the width of the slot. Length is determined primarily by considerations of mechanical strength and stability. The surfaces of the plate and the edges of the slots should, however, be smooth and free from surface defects likely to catch and hold the fibers.

Preferably the perforated screen 5 is extended under the licker-in up to a point closely adjacent to the mote knives, as indicated in Fig. 1, so that theentire screen structure really is a combination cylinder screen and licker-in screen.

This invention has proved in practical operation to produce a substantially better separation of the very short fiber, from the longer staple suitable for spinning than has been obtainable heretofore, so far as I have been able to learn, with cards equipped with the customary forms of screens. The perforated construction of the screen plate 5 is alone an important factor in so controlling the air currents as to reduce very greatly the tendency to discharge good stock slots they are, I believe, thrown through these slots. The action apparently is that as the ends of these fibers, which are lightly anchored in the card clothing, are bent backwardly by their contact with the solid surface of the plate, they tend to be snapped out when they reach one of the slots, so that these ends strike the forward edge of the slot as they are leaving it, and this abrupt contact, which is in the nature of a blow commensurate with the mass of the fiber and its speed of travel, tends to discharge the short fibers through the slots, particularly as this action is repeated many times on an individual fiber during its movement across a long series of these slots. The longer fibers, however, being more firmly embedded in or attached to the card clothing, are not thrown out. In any event, the fact that the separation of these short fibers is improved very materially by the coating of the screen plate with an insulating varnish, has been definitely established.

The dimensions of the slots, particularly their width, appears to be important. I have had the best results with slots between an eighth and a quarter of an inch in width. The spacing'of the slots is not so important but they should not be so close together as to unduly weaken the plate mechanically. I have had the best results by spacing them apart by a distance only slightly greater than the width of the slots themselves. And this width should be selected primarily with reference to the length of the fiber which is to be separated. That is, the width exercises a control over the length of fiber that will be thrown off. Fiber shorter and even slightly longer than the width of the slots will usually be thrown through them but if a fiber bridges the slot by too great a distance, it will not be thrown off.

in the region under the licker-in. However, without the condenser effect produced by coating this plate with an insulating material, the discharged fibers cling to the plate to such a degree as to plug the holes after a relatively short period of operation. This invention utilizes the condenser effect above described in eliminating practically all of this difficulty, as has been amply demonstrated in the practical use of these coated screens in the cards in regular use in a relatively large number of textile mills.

While I have herein shown and described the embodiment of my invention at present preferred, it will be evident that the invention may be embodied in somewhat different forms without departing from the spirit or scope thereof.

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

1. In a cotton carding machine, the combination with a card cylinder, of a metallic screen plate positioned close to the peripheral surface of the cylinder at the lower side thereof, the surface of said plate adjacent to said cylinder being flat and smooth but curved to conform substantially'to the curvature of the cylinder, said plate being perforated substantially throughout its screening area with apertures of such dimensions in the direction of movement of the fibers across the plate as to permit the linters to pass sidewise through said apertures but to prevent the escape of fibers of materially greater length, said plate having a smooth coating of electrical insulating material on both sides thereof, whereby EUGENE C. GWAL'IN EY.

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