US2613521A - Apparatus for handling tricot fabrics - Google Patents

Description

Oct. 14, 1952 L 1... WALMSLEY APPARATUS FOR HANDLING TRICOT FABRICS Filed July 8, 1948 INVENTOR. LESLIE L. WALMSLEX BY Patented Oct. 14, 1952 APPARATUS FOR HANDLING TRICOT FABRICS Leslie L. Walmsley, Ridley Park, Pa., assignor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Application July 8, 1948, Serial No. 37,638

3 Claims. 1

This invention relates to improved means for handling tricot or warp knit fabrics.

This application is a continuation-in-part of my application Serial No. 763,513 filed July 25, 1947.

Such fabrics are produced on conventional tricot warp-knitting machinesby linking or looping the yarns together upon the needles through guides arranged on guide bars, which guide bars traverse the desired. distance from right to left. The fabric leaves the machine in the form of a flat sheet. However, the flat condition of the fabric leaving the knittin machine is temporary, only, and the edges of the fabric undergo spontaneous curling or rolling as soon as the fabric leaves the knitting machine. This edge-rolling of the fabric is in no way related to or caused by strains introduced into the fibers or yarns per se during their production, but is directly due to strains developed in the fabric by the looping or linking of the yarns,. and the tendency of the looped yarns to assume a balanced condition in the fabric in opposition to the strains. If the tricot fabric comprises yarns of a thermoplastic material such as cellulose acetate, the fabric also tends to develop wrinkles or crows feet during subsequent wet treatment, which are set in the fabric and cannot-be removed by pressing or ironing. This spontaneous curling of the selvages of tricot knit fabrics, and in the ease of thermoplastic fabrics the development of Wrinkles or crows feet during subsequent treatment, greatly complicate further handling and finishing of the fabric, especially dyeing, and many proposals have been advanced looking to the elimination of these difficulties.

For example, in the case of fabrics knitted on tricot machines from yarns formed of thermoplastic fibers, it has been proposed to bring the yarns at the edges of the fabric to the plastic or adhesive condition by heat, and to cause cementation of the yarns by pressure. It has also been proposed to soften the yarns at all portions of the fabric, and then to stretch the fabric and subject it to pressure, to both restrain the tendency of the edges to curl, and to inhibit the development of crows feet in the fabric. For fabrics knitted from non-thermoplastic yarns, it has been proposed to apply an extraneous adhesive along the selvages-of the fabric, priorto processing and finishing it or to incorporate yarns of a thermoplastic material with the fabric during the knitting, at the edges thereof, and thereafter activate the thermoplastic yarns to a softened, tacky, or adhesive condition in which, under pressure, they adhere together to form a stiffened, flat edge on the fabric. Other methods of handling the tricot knit fabrics have involved passin the fabric through an uncurling zone prior to introducing it into each of the machines in which the several steps of the processing and finishing procedures are to be conducted.

Obviously, all of these methods have distinct disadvantages. The provision of stiffened or hardened edges on the fabric is objectionable since generally the stiff edges must be cut away priorto use of the material, and prior to scaming thereof necessitating an additional operation and a waste of material. Stretching or pressing of the fabric is also objectionable, because such treatments result in distortion of the stitches and the acquisition of a sleazy appearance by the fabric. The method involvin passing the fabric through a zone in which the edges are temporarily uncurled, prior to introducing the fabric to each of the processing machines, is also objectionable. While the fabric may be held in the flat condition during the passage thereof through, say, a napping machine, it again tends to undergo edge-curlin as soon as it leaves the machine. Moreover, temporary uncurling of the edges is of no use in connection with dyeing.

Actually, in present large scale commercial production, the practice is to sew the edges of the tricot knit fabric together prior to processing it. The fabric is thus processed in the tubular condition. This need for stitching the edges of the fabric together prior to its processing and later removing the stitches, involves a large expenditure of labor and time when a large quantity of fabric is being handled and increases the cost of tricot knitting.

The object of this invention is to provide a means for handling tricot fabrics having curled or rolled edges whereby the disadvantages enumerated above are entirely avoided and the fabric is permanently stabilized in fiat, smooth condition. 'Another object is to provide means for treating a tricot knit fabric having curled edges in such manner that, after the treatment, any tendency of the fabric to undergo spontaneous edge-rolling is permanently eliminated. A specific object is to uncurl the edges of a tricot fabric and eliminate the tendency of the fabric to undergo edge-rolling, prior to dyeing thefabric, thus making it possible to dye the fabric in the flat condition in which it is produced initially. Another specific object is to 'uncurl the edges of a tricot fabric and eliminate further Curling-thereof by subjecting the fabric having the curled edges to a single uncurling operation. A further object is to uncurl the edges of a tricot fabric comprising yarns of a thermoplastic material, and to simultaneously render the uncurled condition permanent and inhibit the development of wrinkles or crows feet in the fabric. Another object is to provide means whereby spontaneous rolling of the edges of a tricot fabric is permanently eliminated without distortion of the stitches of the fabric.

These and other objects are accomplished by the provision of apparatus comprising, in combination, means for uncurling the edgesof a tricot fabric which has undergone spontaneous edgecurling after leaving the knitting machine, and means for treating the uncurled fabric, in a substantially tensionless condition, and in the absence of pressure, to effect complete relaxation of the strains developed in the fabric during looping of the yarns, thereby permanently relieving the tension in the fabric which is responsible for the spontaneous edge-rolling, permanently eliminating the tendency of the edges to curl or roll spontaneously, and rendering the flat, smoothcondition of the fabric resulting from. the uncurling and relaxing treatments substantially permanent. Fabrics treated in accordance with. the invention remain in the smooth, flat condition until they are permanently shaped to tubular. or threedimensional form. The fabric may be dyed, and/or otherwise processed as desired in the flat condition, without exhibiting any tendency to edge-rolling, and, in the case of fabrics knitted from yarns of thermoplastic materials, any tendency to wrinkling or the development of. crows feet during processing. Because the strains set up, in the fabric by looping of theyarns are permanently relaxed, it is only necessary to treat the fabric having the curled edges once to insure that, after the treatment, the fabric will thereafter remain in the fiat condition until it is shaped. No extraneous adhesive or other coating is applied to the edges of the fabric. When the fabric com prises yarns of a thermoplastic material, dry heat may be employed to effect the relaxation. However, in the preferred embodiment of the invention, the fabric, whether comprising thermoplastic or non-thermoplastic yarns, is treated with a heated liquid which has a slight swelling action only on the yarns, the temperature of the liquid being moderate as compared to the temperature at which, if the yarns of the fabric are thermoplastic, they undergo any appreciable softening. The particular liquid employed,,and the temperature thereof, will depend upon the nature of the yarns constituting the fabric.

In specific embodiments, the apparatus comprises a vessel containing a heated liquid which has a swelling action on the yarns but does not appreciably soften the yarns, means for advancing the tricot fabric having curled edges in a predetermined path in the absence of stretching tension and pressure, to and through the heated liquid, means in the path of the fabric and, immediately adjacent the point of introduction of the fabric into the heated liquid, for uncurling the edges of the fabric, and means for maintaining the fabric in the flattened, uncurled condition as it passes through the heated liquid, whereby the strains in the fabric resulting from looping'of' the yarns during the knitting operation are completely relaxed.

Water at a temperature of about 100 C. is preferred when the tricot fabric is knitted from cellulose acetate yarns which are not plasticized. If

the cellulose acetate yarns are plasticized, i. e., if they contain an extraneous plasticizing agent for lowering the softening point of the cellulose acetate, the temperature of the water or other liquid is adjusted so that it is substantially below the softening point for plasticized yarns.

Preferred forms of apparatus in accordance with the invention are illustrated in the accompanying drawing, in which Fig. 1 is a side elevation of one embodiment;

Fig. 2 is a view taken on line II-II of Fig. 1;

Fig. 3 is a side elevation of another embodiment;

Fig, 4- is a view. taken on line IV-IV of Fig. 3; and.

Fig. 5 is. a side elevation of a further embodiment.

Referring to Figs. 1 and 2 there is shown a vessel 2 containing water maintained at a temperature of. C. Supported in the vessel, below the level of. the water are a pair of endless bands 3 and 4 which. travel around the pairs of pulleys 5.- and 6, driven by any suitable means (not shown) in the direction of the arrows, and so. that. the adjacent surfaces of the bands travel in the s amedirection. The bands are supported in spaced apart relation, the distance between the. adjacent surfaces thereof being sufficient to permit passage of the fabric 1' therebetween and insufficient to permit curling of the selvages thereof. The exact distance between the adjacent. surfaces of the endless bands will depend upon the'thickness of the 'fabric being. handled, the. critical feature beingthat the bands prevent curling of the edges of the fabric without exerting pressure thereon. The uncurling means shown is a wire 8. bent to. trapezoid shape, and provided with stiffening members 9 and Illv which are fixed .to bracket H bolted on the upper edge of vessel 2.. The trapezoid is fixed in an inclined. position, with respect to the edge of the vessel and the'space between the endless bands 3. and 4, and members 9 and. ID are bent so that they follow the curve of they rollers and extend a, short distance into thev space between the bands. In operation, the tricot fabric having curled edges, as shown at l2, for example such a. fabric comprising cellulose acetate yarns in unplasticized condition, is passed over guide roll [3. downwardly into Vessel 2, and over the trapezoid 8.. As the fabric. advances over the trapezoid. to the space between the bands 3 and 4, edge M of the trapezoid 8 slips under the curled edge of the fabric and initiates the uncurling. As the fabric proceeds over the trapezoid, the outwardly and downwardly inclined sides of thelatter serve to effect further uncurling of the curled edges, with flattening of the fabric. The flat fabric leaves the trapezoid 8 and passes directly into the space between the bands 3. and 4' between which it is maintained in the flat condition' Under the action of the hot water, the 'strains'introduced into the fabric during' the knitting'are relieved, and the fabric as a'whole is stabilized in flat, smooth condition. The stabilized flat, smooth fabric is withdrawn from the vessel over the guide roll l5 by the withdrawing rolls l6 and IT.

The hot 'watereffccts a. slight swelling of the yarns withresulting contraction of the fabric. The rates at-which the fabric is introduced into the hot water and withdrawn therefrom are correlated to permitcontraction of the fabric due to slight swelling of the yarns without subjecting it to stretching or tautening tension. The fabric cpl-352i is maintained in essentially 'tensionless condition during the heat treatment. The time of exposure of the uncurled flat fabric to the heated liquid is usually short, ofthe order of a few minutes.

After its withdrawal from the heated liquid, the fabric may be cooled, if desired, to facilitate handling thereof. Such cooling may be effected by passing the fabric through a vessel containing cold water, or by subjecting it to astream of cold air as it passes over the guide roll l5.

In the embodiment shown in Figs. 3 and 4, the tricot fabric |8, such as a cellulose acetate fabric knitted from yarns of unplasticized cellulose acetate, passes over the roller I9 downwardly over the inclined guiding surface 20 and is fed between two stationary guide plates 2| and22 submerged in the hot water contained in vessel 23 and disposed, one above the other, in spaced relation, to provide a passageway for .the fabric therebetween, and is withdrawn from the liquid over the roller 24 by the withdrawing rollers 25 and 26. As shown, the guiding surface 20 is a plate-like member and both it and the guide plates 2| and 22 may be made of any suitable material, preferably a highly polished metal, such as stainless steel. Member 20 is fixed in inclined relation to the guide plates 2| and 22 and the roller l3, and extends directly to the mouth of the space between those plates so that the fabric passes directly from the member 20 into the space between the plates. The uncurling means is supported above member 20, immediately adjacent the mouth of the space between the plates 2| and 22, and as shown, is constituted by two jets 21 and 28 adapted to project fiuid under pressure outwardly against the curled edges of the fabric, the fluid being preferably a liquid which is the same as the heated liquid in vessel 23. The fabric passing over rollers l9 may be treated with liquid, for instance by means of the spray head 29, to facilitate sliding of the fabric over the inclined surface 20. The opposite ends of plate 2| are curved or flared upwardly, and the opposite ends of plate 22 are curved or flared downwardly to facilitate feeding of the fabric between the plates and withdrawal of the fabric from theliquid.

The distance between the guiding surfaces of plates 2| and 22 is sufiicient to permit the fabric to pass freely between the plates, but insuff cient to allow room for the edges of the fabric to curl upwardly, and the fabric is automatically maintained in the flat condition resulting from uncurling of the edges by the jets of liquid immediately prior to introduction of the fabric into the space between the plates.

It is of the utmost importance that the fabric pass through the liquid without being subjected to stretching or tautening tension. The rate at which the fabric is passed into the liquid bath and the rate at which it is withdrawn therefrom are correlated to insure that the fabric is substantially tensionless in the liquid, so that the strains present in the fabric are relieved. If the fabric were stretched or tautened the strains would not be relieved, and the tendency of the selvages to curl would not be eliminated. In the preferred embodiment, when the tricot fabric is knitted of cellulose acetate yarns, the rate at which the fabric is passed into the liquid and the rate of withdrawal are correlated to give the fabric a five minute immersion in the heated liquid without subjecting it to a stretching tension.

passed under the single guide plate 34 supported in the heated liquid contained in vessel 35, being withdrawn from the liquid over the roller 36 by the withdrawing rolls 31 and 38, the rate of feed of the fabric to the liquid, and the rate of withdrawal being correlated so that the fabric passes through the liquid in a substantially tensionless condition. The fabric traveling through the liquid rides against the guiding surface of plate 34 and is maintained in the flattened condition to which it is brought by the fluid streams projected against the selvages as the fabric leaves the inclined guiding surface 32 and passes immediately into the liquid and under the guide plate 34. In practicing this last-mentioned embodiment 'of the invention, the heated liquid may have a specific gravity greater than water, so that it inhibits any tendency of the fabric to sag in the bath and tends to buoy up the fabric and maintain it in the flat condition against the surface of the guide plate 34. For example, the heated liquid may be an organic solvent or water containingadissolved salt, which may or may not assist in swelling the yarns of the fabric. For example, in the case of regenerated cellulose tricot fabrics, the heated liquid may be water containing sodium hydroxide in a concentration of from 1 to 5%.

The advantages of the invention are multiple. By the use of the apparatus described, tricot fabrics are not only brought to a condition in which spontaneous edge-rolling is permanently eliminated, with permanent stabilization of the fabric as a whole in the fiat, smooth condition, which in turn eliminates any necessity for stitching the edges of the fabric together and treating it in tubular-form, prior to processing and finishing it, but this is achieved under conditions'such that distortion of the stitches of the fabric is entirely avoided, the loops being fixed in the exact pattern imposed thereon by the knitting needles. All tendency to wrinkling of, or the development of crows feet in, thermoplastic fabrics is also eliminated, and such fabrics remain flat and smooth throughout the subsequent stages of the processing and finishing treatments.

Since spontaneous edge-rolling of the tricot knit fabrics is eliminated and stabilization of the fabric as a whole in flat, smooth condition is effected without adversely affecting the yarns, for example, without stiffening or coalescence of the yarns, the fabrics treated in accordance with the invention are useful for all textile purposes. The knit fabrics which are stabilized in the fiat condition have a soft, pleasing hand or feel and are entirely free from the sleaziness which is often an objectionable feature of jersey or jerseytype fabrics.

The saving in time and expense made possible by the practice of the invention is impressive, and tricot knitting on a large commercial scale is rendered both practicable and economical.

since some modifications may be made in carrying out the invention Without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined in the appended claims.

actual,

Iclaim:

1. Apparatus for uncurling the. selvages of a tricotfabric having, curled selvages and for. stabilizing the fabricin flat, uncurled condition which. comprises, in. combination, a vessel for containing a heated liquid, a horizontal roll outside and above the vessel adjacent one end there of, a guiding member extending lengthwise, between the ends of' the vessel and having a width at least as great as the. full width of the fabric supported inthe heated liquid and having a smooth, continuous lower surface defining the upper side of a. path for the fabric through the liquid and preventing curling of the fabric passing through the liquid, means comprising a driven roll adjacent the other end of the vessel for moving the fabric from the first roll downwardly under the guiding member through the heated liquid, a. stationary inclined plate extending downwardly from a position adjacent the firstmentioned end of the vesselto a position in proximity to the adjacent end of the lower surface of the guiding member,- and uncurling means comprisinga pair: of'means disposed adjacent the plate inwardly of its edges and oppositely and laterally outwardly directed with respect to the path of the fabric thereover for spreading the selvages of the fabric out against the plate, said spreading means being supported: between the roll and the guiding member immediately adjacent the entrance to' the path defined by the lower surface-of the guiding member for rolling back the selvages ofthe fabric as it enters said path.

2. Apparatus for uncurling the selvages of a tricot fabric'having curled selvages and for. stabilizing the fabric in fiat uncurledcondition which comprises, in combination, a vessel for containing a heated liquid, a horizontal roll outside and above-the vessel adjacent oneend thereof, a guiding member extending lengthwise between the ends of the-vessel and having a width at least as great as the full width of the fabric supported in the heated liquid and having a smooth, continuous lower surface defining the upper side of a path for the fabric through the liquid and preventing curling of the fabric passing through the liquid, means. comprising a driven roll adjacent the other end of the vessel for moving the fabric from the first roll downwardly under the guiding member through the heated liquid, a stationary inclined plate extending downwardly from a position adjacent the first-mentioned end of the vessel to a position in proximity to the adjacent-end of the lower surface of the guiding member and uncurling means comprising a pair of oppositely and laterally outwardly directed fluid jet means disposed adjacent the plate inwardly of its edges for spreading the selvages of the fabric out against the plate, said jet means being supported between the roll andthe guiding member immediately adjacent the entrance to th path defined by the lower surface of the guiding member for rolling-back the. selvages of the fabric as it enters said path.

3. Apparatus for uncurling the selvages of a tricot fabric having curled selvages and for stabilizing the fabric in fiat, uncurled condition which comprises, in combination, a vessel for containing a heated liquid, a horizontal roll outside and above the vessel adjacent one end thereof, a pairv of guide plates each extending lengthwise between the ends of the vessel and having a width at. least as great as the full width of the fabric supported one above the other in the heated liquid, the upper of said plates having a smooth, continuous lower surface terminating in upwardly curved ends and. defining the upper sidev of. a path for the fabric, the lower of said plates having a smooth upper surface terminating in downwardly curved ends and defining the lower side. of, the path. for the fabric, the path through. the liquid defined by the smooth surfaces of. the plates having a depth greater than the. thicknessof the fabric but less than the depth which would permit curling of the fabric passing between the plates, means comprising a driven roll adjacent the other end of the vessel for moving the fabric from the first roll downwardly under the guiding member, through the heated liquid,. a stationary inclined plate extending downwardly from a position adjacent the first-- mentioned end of the vessel to a position in proximity to the adjacent end of the lower surface of the upper guiding member and uncurling means comprising. a pair of fluid jet means disposed adjacent the inclined plate inwardly of its edges and oppositely andlaterally outwardly directed against. the selvages for spreading the selvages of the fabric out against the inclined plate, said jet. means being supported between the roll and the guiding members immediately adjacent the entrance end of the path defined by the pair of plates for rolling back the selvages of the fabric as it enters said path.

LESLIE L. WALMSLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 430,925 Corron June 24, 1390 1,052,399 Ashworth Feb. 4, 1913 1,220,268 Payet Mar. 27, 1917 1,432,318 Brandwood Oct. 17, 1922 1,912,724 Remington June 6, 1933 1,913,601 Leppin June 13, 1933 2,252,659 Kenyon Aug. 12, 1941 2,267,117 Mann Dec. 23, 1941 2,276,605. Andrews Mar. 17, 1942 2,365,931 Benger' Dec. 26, 1944 2,402,621 Gifford June 25, 1946 2,441,308 Bond May 11, 1948 2,474,717 Belcher June 28, 1949

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