US2588624A

US2588624A - Method of finishing knitted fabric

Info

Publication number: US2588624A
Application number: US115007A
Authority: US
Inventors: Evans Richard
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-09-10
Filing date: 1949-09-10
Publication date: 1952-03-11
Anticipated expiration: 1969-03-11

Description

March 1952 R. EVANS, 2ND

METHOD OF FINISHING KNITTED FABRIC Filed Sept. 10, 1949 A rrazzvsys Patented Mar. 11, 1952 UNITED STATES TENT OFFICE METHOD OF FINISHING KNITTED FABRIC Richard Evans, 2nd, Johnstown, N. Y.

Application September 10, 1949, Serial No. 115,007

8 Claims.

My invention relates to the finishing of knitted textile fabrics and particularly to the finishing of tricots.

Tricot fabrics, for example, are knitted flat and, in the knitting operation, the threads or yarns which are looped together are under substantial tension. As the fabric passes beyond the zone of the looping operation the width thereof becomes very materially reduced, due to the fact that there is no longer anything to hold the fabric to its original, knitted width, and the internal stresses which have developed in the fabric relieve themselves by effecting a substantial narrowing of the width thereof. Fabrics of this type when stressed transversely in tension become shorter as measured longitudinally, and,

when subjected to tension in a longitudinal direction become narrower as measured transversely thereof. Moreover, while courses of the fabric, as knitted, run in a direction at right angles to the longitudinally-extending edges thereof, these courses, after the fabric leaves the machine, cease to be straight and parallel to each other and extend in irregular lines transversely of the fabric. Furthermore, the edges of the fabric are not straight and the width is not uniform.

' elevation view, partially in section, of a calendering device;

Fig. 4 is a plan view of Fig. 3;

Fig. 5 is a diagrammatic, plan view of a fragmentary portion of a knitted fabric after it leaves the knitting machine;

Fig. 6 is a view of the fabric shown in Fig.5 after it has been folded along the longitudinal centerthereof and the edges stitched together to form a tubular structure; and

Fig. '7 is a section of Fig. 6 in the plane 1-1.

Referring to the dra ings:

As the fabric I leaves the knitting machine,

' or at any other time before washing, scouring or In finishing a knitted fabric for the trade, it is quite necessary so to treat it that the edges are straight, and the courses therein are straight and parallel and run transversely of the fabric in a direction normal to the edges thereof. Perfectly straight courses are particularly necessary where the fabric is knitted in straight, colored strips running transversely thereof.

A knitted fabric may be washed or otherwise treated so that it shrinks either in length, or width, or both, but such shrinkage is not permanent, and the fabric can be pulled back to its original size by applying tension thereto in the proper directions. In other words, the fabric, or the shrinkage thereof, is dimensionally restorable. Where the fabric is set to size, or has a permanent shrinkage imparted thereto, it is not restorable to its original size, and, although it can be stretched under tension, it will return to its set. or perm ently shrunken size as soon as the tension is relieved.

The principal object of my invention is to provide a method of treating a knitted fabric in such a way that the width and length thereof under normal, unstressed conditions become substantially constant or fixed, although the fabric may be readily stretched under tension either longitudinally or transversely. Another object is to provide a method of procedureby means of which the fabric may be quickly and economically treated to effect a setting and finishing thereof in a substantially continuous operation. A further object is to provide a method of treating knitted fabrics whereby they are endowed with high resistance to shrinkage when subjected to wet processing or Washing,

dyeing, marks, such as shown at 2, 3, 4 and 5, are applied to the opposite ends of spaced courses such as shown at 6, I, 8 and 9, respectively. 4 The fabric is then folded transversely to bring the opposite lateral edges thereof together with the opposite ends of the courses coincident with each other, as shown in Fig. 6, and the edges are then secured together by stitching III to form a tubular structure, such as shown at H in Fig. '7. These steps may be performed by hand, by machine, or by apparatus such as disclosed in U. S. Letters Patent No. 2,321,010 granted to S. Cohn on June 8, 1943..

The fabric in tubular form is then ready for the usual washing, dyeing, scouring, etc., but, in any event, it is thoroughly wetted before further treatment" and the excess moisture is removed by centrifuging or other water extracting methods. While still in the moist condition, the

- fabric is first subjected to a treatment designed to straighten the courses, and the lateral edges thereof and, at the' same time, to relieve all internal stresses existing. therein. These steps might be manually performed but in commercial production it is far more practical to do it mechanically by means of the app ratus described next below in connection with Figs. 1 and 2 of the drawing.

The moist, tubular, fabric structure H may be placed in a basket [2 so that it may be progressively withdrawn therefrom. The end of the tube is slipped over the U-shaped wire l3 and the lateral edges thereof are passed through the edge-driving mechan sm represented generally at I 3. This mechanism comprises two grooved,

rubber, driving pulleys l5, both of which are driven at the same speed by shafts, one of which is shown at It in Fig. 1 and by other mechanism (not shown). Running in the groove of each of the pulleys I5 is a pair of driven rolls H and I8 which are held in spaced relation and within said grooves by means of the bar l9. Edge-driving mechanisms of this general character are well known in the art and usually include a speed regulating device by means of which the rate at which the pulleys l5 turn may be varied. The opposite edges of the fabric are carried between the rolls and the pulleys, and beyond the edgedriving mechanism, theedges of the fabric are supported and h'eldin spaced'relation by means of the small disk-likerollers 20 which are supported on rods 2| extending from theedge-driving'mechanism.

As the fabric is drawnover thewire 13, the

contact of the wire with the edges of the fabric tends to retard the forwardmovement'of said edges with the result that, in the zones where the fabric first encounters the wire, the central portions of the courses advance-faster than the..-

edge portions sothat said courses are curved as shown at 22 in Fig. 2;

Thefunction of the edge-driving mechanism (4 is to overcome this drag so that the courses are gradually straightened as they approach said mechanism and are straight or substantially straight after they pass it, as shown at 23.. After the edges and courses have been straightened and'all of the internal stresses in the fabric' have been 'relievedithe fabric" is in a completely re-m by placing the fabric in fully relaxed condition.

betweentwo layers of other fabric and holding every portion thereof in fixed relation to every other portion 'by'the application of pressure uniformly distributed thereover while effecting a flow of hot air therethrough. Commercially, this step.

is best performed-in a continuous way by mech-' anism-such as shown in Fig; 1, in which 24 is the casing or housing of a drier and 25 is a rotatable,'driven'cylinder having aperatures 26 in the surface'thereof. Hot air supplied to the interior' of the casingis drawn through these apertures, as shown by the arrows 21, into the inter'ior" of the cylinder 25, and is drawn out through the hollow shaft 28 having perforations or' apertures 29 therein. with the surface of the cylinder 25 is a porous cloth belt 30 which maybe formed of cider press cloth andwhich runs upwardly as it leaves the-drying chamber, passes over the rolls 3:, 32, 33, 34 and 35,"and back to the drying chamber. Also running around the-drying cylinder outside of the belt '50 is a second' porous cloth belt 36 whichruns over the rollers'3'l and. 38 at the entranceto'thedrying chamber and'over the rollers 39; 49, 4| chamber.

The-disk guides 20 are positioned closely adjacent the pinch '43 of the belts '30 and 3B, and the fabric, in the fully relaxed condition as described above, passes into thi pinch and aroundi the cylinder between said belts to emerge on top of the belt 30 by means of which it is conveyed either directly to a calendering device in a continuous operation or redeposited in a backet 44.

From the foregoing it will be apparent that,

the fabric which passes initially between the belts in a fully relaxed condition is maintaine i that Running in contact and '42 at the corners of 'the.

4 l condition throughout its passage around the drying cylinder because of the pressure which the belt 36 exerts thereon and which, in cooperation with the belt 30,'holds every portion of the fabric in positively fixed relation to every other portion thereof. The hot air passing through the belts dries the fabric.

While a calendering treatment is not necessary with some fabrics, nevertheless, it is desirable in most instances, after the fabric has been dried in the fully relaxed condition, to subject it to such av treatment. In Figs. 3 and 4, I have illustrated a standard calender which is provided with a U-shaped wire t3, edge-driving mechanism l4. and guiding disks. 20, in all respects similar to the like numbered parts in Figs. 1 and 2. The fabric is drawn over the wire l3, passes through the edge-driving mechanism 14, through the heated calender rolls 45 and 46, and is wound on a roll 41.. As-the fabric is being drawn over the wire .13, steam 8 passes therethrough from the apertures 39 in the steam pipes 50 .and 5|. After calendering,the stitched edges of the fabric .are- .separatedby cutting or removing the stitches.

It is very important that the fabric, after it leaves the edge-driving mechanism on its way to the drier, be maintained in a fully relaxed condition, not only-just before it passes into the drier but, aspointed out above, throughout its passage through the drier. Bearing in mind that a knitted fabricbecomes shorter longitudinally when it is stretched orpulled transversely, and that such a shortenin takes place as the fabric passes the edge-driving mechanism, it is quite essential that 'the-edge-driving mechanism be adjusted to pass the fabric at a somewhat higher rate of speed than its rate of travel around the drying cylinder, in order to compensate for this shortening. 'Inother-words, the peripheral speed of the driving pulleys IS in the edge-driving mecha nisrn', where they contact the fabric, must be adjusted so that it is somewhat greater than the peripheral speed'of the fabric as it passes around the drying cylinder.

By treating fabric in the manner described above it is set to a definite width and length which it will automatically assume when in fully relaxed, unstressed-condition. It can, of course, be stretched in a direction either longitudinally or transversely thereof by the application of tension but, whenthe tension is relieved, the fabric will automatically return to its set dimensions.

Whysuch'results are obtained when the fabric driedbetween two layers of another fabric rather than by merely holding it, or attempting to hold it, in fully relaxed condition on the cylindrical s'urfaceof a drier by means of a single overlying belt or layer of fabric is not entirely clear. It might be dueto the fact that the driving stress from the cylinder to a single overlying belt 'must' be transmitted through the knitted fabric and therefore creates distorting strains in the'fabric.

Onthe other hand, by placing the knitted fabric between. two belts the strains which the overlying belt tends to create in the fabric, as the assembly l is flexed around the drying cylinder, may be neutralized by the strains which the underlying belt tends to create therein. In other wordsfthe fabric lies against the concave side of the'outer belt which tends-to compress the fabric longitudinally, and against the convex side of the inner belt which tends'to stretch the fabric 10ngitudinally, as the movement of the belts, with the fabric therebetween, changes from a straight line movement to a curvilinear movement where the belts become tangent to the drying cylinder.

In any event, my results can only be obtained by holding the fabric throughout in a wholly relaxed condition during the drying thereof.

While my process is not limited in its application to knitted fabrics formed of synthetic yarns, such as viscose, acetate, rayon, and the like, it is particularly effective in the finishing of tricots formed of such materials for which, heretofore, so far as I am aware, there has been no entirely satisfactory method.

Where the fabric is knitted in tubular form instead of fiat, the steps of folding the fabric and stitching the edges together to form a tubular, fabric structure are, of course, not necessary.

What I claim is:

1. Those steps in the method of setting a knitted fabric to a substantially fixed size which said fabric will assume when in a normal unstressed condition and which comprise, bringing said fabric while moist into a fully relaxed condition substantially free of stress, and thereafter subjecting said fabric in said fully relaxed condition to a drying treatment while holding substantially every portion thereof in fixed relation to every other portion thereof.

2. Those steps in the method of setting a knitted fabric to a substantially fixed size which said fabric will assume when in a normal unstressed condition and which comprise, bringing said fabric while moist into a fully relaxed condition substantially free of stress, and thereafter subjecting said fabric in said fully relaxed condition to a drying treatment by creating a flow of air at elevated temperature therethrough while holding substantially every portion thereof in fixed relation to every other portion.

3. Those steps in the method of setting a knitted fabric to a substantially fixed size which said fabric will assume when in normal unstressed condition and which comprise, bringing said fabric while moist into a fully relaxed condition substantially free of stress, placing said fabric in said fully relaxed condition between layers of another fabric and holding it between said layers in said condition by the application of pressure while subjecting it to a drying treatment.

4. Those steps in the method of setting a knitted fabric to a substantially fixed size which said fabric will assume when in normal unstressed condition and which comprise, bringing said fabric while moist into a fully relaxed condition substantially free of stress, placing said fabric in fully relaxed condition between layers of another fabric and holding it between said layers in said condition by the application'of pressure while subjecting it to a drying treatment by creating a flow of air at elevated temperature therethrough.

5. The method of setting a flat knitted fabric to a substantially fixed size which said fabric will assume when in a normal unstressed condition and which comprises folding said fabric transversely to bring the opposite, longitudinally-extending edges thereof together; stitching said edges together with the opposite ends of the courses substantially coincident at the stitching to form a tubular, fabric structure; subjecting said structure while moist to a relaxing treatment to bring said courses into substantially parallel disposed relation to each other and to free said fabric of internal stresses tending to distort it; placing said fabric when in fully relaxed, stressfree condition between two layers of another fabric and maintaining it in said condition while subjecting it to a drying treatment.

6. The method of setting a fiat knitted fabric to a substantially fixed size which said fabric will assume when in a normal unstressed condition and which comprises folding said fabric transversely to bring the opposite, longitudinally-extending edges thereof together; stitching said edges together with the opposite ends of the courses substantially coincident at the stitching to form a tubular, fabric structure; subjecting said structure while moist to a relaxing treatment to bring said courses into substantially parallel disposed relation to each other and to free said fabric of internal stresses tending to distort it; placing said fabric when in fully relaxed, stress-free condition between two layers of another fabric and maintaining it in said condition by the application of pressure while creating a flow of air at elevated temperature therethrough to effect a drying thereof.

7. The method of setting a fiat knitted fabric to a substantially fixed size which said fabric will assume when in a normal unstressed condition and which comprises, forming said fabric into a tubular structure by folding it transversely and securing the folded edges thereof together, continuously progressing said structure in a direction longitudinally thereof, subjecting said structure to a spreading treatment to straighten the opposite edges thereof and bring them into parallel disposed relation and also to straighten the courses thereof and bring them into parallel disposed relation to each other, relieving said structure of all internal stresses tending to distort it, placing it in the unstressed condition between two layers of another fabric and applying pressure to said layers to hold said structure therebetween in the unstressed condition, and drying said structure while between said layers by creating a flow of heated air therethrough.

8. The method of setting a fiat knitted fabric to a substantially fixed size which said fabric will assume when in a normal unstressed condition and which comprises, forming said fabric into a tubular structure by folding it transversely and securing the folded edges thereof together, continuously progressing said structure in a direction longitudinally thereof, subjecting said structure to a spreading treatment to straighten the opposite edges thereof and bring them intoparallel disposed relation and also to straighten the courses thereof and bring them into parallel dis-' posed relation to each other, relieving said structure of all internal stresses tending to distort it, placing it in the unstressed condition between two layers of another fabric and applying pressure to said layers to hold said structure therebetween in the unstressed condition, drying ,fsaid structure while between said layers by creating a flow of heated air therethrough, and thereafter subjecting said structure to a calendering treatment.

RICHARD EVANS, 2m).

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

UNITED STATES PATENTS Redman Apr. 20, 1948