US3314123A - Method of knitting fabrics without permanent deformation - Google Patents

Description

April 18, 1967 G. GROEBLI 3,314,123

METHOD OF KNITTING FABRICS WITHOUT PERMANENT DEFORMATION Filed Dec. 9, 1963 2 Sheets-Sheet 1.

G. GROEBLI 3,314,123 METHOD OF KNITTING FABRICS WITHOUT PERMANENT DEF'ORMATION April 18, 1967 2 Sheet$-Sheet 2 Filed D60. 9, 1963 United States Patent 3,314,123 METHOD OF KNITTING FABRICS WITHOUT PERMANENT DEFORMATION Gustave Groebli, Saint-Quentin, France, assiguor to Societe Anonyme le Textile Delcer, Saint-Quentin, France, a French society Filed Dec. 9, 1963, Ser. No. 329,939 Claims priority, application France, Dec. 8, 1962, 918,016; Nov. 29, 1963, 955,437 2 Claims. (Cl. 28-72) The present invention rel-ates to knitted fabrics having improved properties as regard permanent deformations (here called pouchin-g). Knitted fabrics in accordance with the invention have inextensibility aspects and characteristics similar to those of fabrics made on weaving looms, but keep the advantages and qualities of knitted fabrics; such knitted fabrics may be supple, if required, and are lower in cost than woven fabrics.

The principle, when using a warp knit and Raschel loom, consisting of inserting unknitted straight filling threads between the columns of the stitches, is known. The fabrics thus produced, regarding aspect, looked like woven fabrics, but no real use of such fabrics has been made, except for their use as curtain or drape fabrics. Curtain fabrics, which merely hang and are decorative, do not require any characteristics needed for fabrics employed for tailor-made clothes and the like.

In fact, the essential characteristic of a fabric for clothes, for seat covers and the like, is the lack of permanent deformation commonly called pouching. Pouching is a characteristic of hitherto known knitted fabrics.

The inventor has found that, to suppress all permanent deformation or poaching, it was necessary that:

(l) The fabric should be completely inextensible or, at least, that all permanent or elastic lengthening be suppressed, at least in the warpwise direction of the fabric.

(2) There should be no possible slipping of the threads working as weft threads with regard to unknitted straight threads working as warp threads. (In order to overcome such tendency, it is enough to draw up the cloth warpwise in pinching only the columns of stitches.)

The present invention relates to a knitting method that takes the above into consideration, and that allows the production of a knitted fabric without permanent deformation.

This process in which unknitted filling threads are inserted between the columns of stitches, is characterized by the use, for the columns of stitches, of a chain-stitch thread having the property of being more highly retracted than the filling threads; this chain-stitch thread is able to be fixed or set, after retractation, by thermo-setting, for instance.

It is necessary in accordance with the invention that the initial length of the chain-stitch thread used during the knitting be nearly equal to the theoretical length in order to obtain inextensible columns of stitches after the retractation treatment of the fabric.

For all purposes, the stitch cycle is repeated to form the binding combination, the chain-stitch thread having a minimum length warpwise or longitudinally of the fabrics. The process according to the invention can be used for many binding combinations types, mainly for those in which a chain-stitch thread operates between several columns of stitches; in this case the chain stitch thread works as a weft thread. The chain stitches do not have any deformation capacity by lengthening after the retractation treatment, since the curve of the stitches is completely resorbed by such treatment. The columns of stitches have changed, after retractation, in a complex comparable to a three ends twist that, gathered to the Weft threads and to the filling threads, creates a fabric which presents practically woven fabrics characteristics.

The invention will be more readily understood and several other characteristics as well as advantages will appear after consideration of methods decribed in the attached figures.

FIGURE 1 is a knitted fabric according to the invention process before retractation treatment.

FIGURE 2 is a view of the fabric shown on FIGURE 1 after retractation treatment.

FIGURE 3 is a View of other fabric made according to the invention.

In FIGURE 1 there is shown a fabric which includes on one side a row of chain-stitch threads 1 making columns of stitches or wales andweft threads 2 and 3 which are operative on the right and left of the chain-stitch threads 1 and link therewith to form stitches in a marquisette pattern. On the other side the fabric is provided with filling or reinforcingyarns 4 inserted without knitting in a parallel direction between the columns of stitches. To simplify the figure there is shown only one filling 3 thread between two columns of stitches, but it will be obviousthat, as a rule, such a filling thread is put between two columns of consecutive stitches. As well, in each column of stitches there are weft threads such as those designed by 2 and 3 linked with each Wale, but here again there is only one thread for each of the two groups located the first one before and the other one behind the filling threads.

In order that this cloth does not pouch it is necessary:

On one side that the traction efforts be supported bythreads 4 which are inextensible (except. for natural elasticity of the threads) as they are straight and without undulations.

On the other side that the column ofstitches 1 that maintain the waft-like threads 2 and 3 in their loops must not be allowed to be stretched beyond the elastic limit of the chain-stitch yarn, for if any such stretch were to occur, theyarns 2, 3 would slide, with no chance of being returned to their correct position, upon theyarns 4.

. But the technician knows that this last condition cannot be realized on a knitting machine as it is nearly impossible to realize a chain-stitch having. no mechanical lengthening due to:

(a) Necessity of using a chain stitch thread length much longer than corresponding length of this chain stitch itself (regarding the undulations).

(b) The round shape of a stitch.

(c) Flexibility (or live handle) of any textile thread.

According to the invention to satisfy this condition, there is used for the columns stitches, athread 1 having a higher shrinkage than that of thefilling yarns 4 and being, besides, able to be fixed up in its shrunk position. We can use a thermo-set thread like a polyamide or polyester. It is also necessary that the delivered length ofthread 1 be in a judicious ratio with corresponding length ofthread 4. during knitting to make the repeat of the binding combination must be such that after retractation the retracted length A A' (FIGURE v2) ofthread 1 of the same repeat corresponding to this of an inextensible stitch, that is to say, showing no empty space allowing elongation.

After knitting, the fabric is put through a shrinkage treatment at the setting temperature of molecules ofthread 1, this treatment being made with the fabric maintained under a desired tension in order that final length of this cloth be equal to the delivered length of thefilling yarns 4, but under consideration of the retractation of these filling threads. This latter retractation is very limited, only a few percent.

If for instnace 53 meters of filling yarn layers to knit 50 meters of cloth, the maintained tension during the In fact, length AA ofthread 1 used treatment will be such that the final length of the piece of cloth will be 53 meters. However, if the filling yarns presented a 2% shrinkage, the tension during treatment would be such as the final length of the piece of cloth is 52 meters.

In FIGURE 2 we see that after shrinkage the stitches of the various diflferent columns or wales are completely lengthened, each column being comparable to a three ply yarn. Unlike FIGURE 1, in FIGURE 2 we have been able to showseveral filling yarns 4, each of them being arranged between two columns or wales of stitches.

The length AA ofthread 1 that is required in the column or wale of stitches, must agree nearly precisely with length BB ofstraight thread 4. Accordingly, after many experiments applicant has devised a formula for determining the choice of yarns to be used in dependence upon the knitting possibilities of a particular kind of loom. In these experiments, some of the factors varied were the characteristics of the yarns used and the number of stitches per centimeter of fabric length.

This formula that can be applied in the case of a chainstitch thread is used for only one column of stitches, gives the ratio X of the supply of chain-stitch thread 1 used in the column of stitches to the supply of thefilling yarn 4;

in which:

D=density of chain-stitch thread that works in the column of stitches,

N =metric number of this same thread when knitting,

R=shrinkage of the chain-stitch thread relative to the filling yarns, that is to say the complement to unity of the difference between the shrinkage of the chain-stitch thread and of the filling yarn,

M=number of stitches required per unit length of shrunk fabric.

Of course, the technician is obliged to make a judicious choice of yarns with special characteristics to obtain a ratio X intermediary between the two limits corresponding to a reasonable running of the knitting machine at his disposal. In certain cases We also can look for threads corresponding to a predetermined ratio X.

The above-mentoned formula has a precision corresponding to that of its elements and in particular the (relative shrinkage) which may vary with the yarns used.

So, for instance, variations of R of more or less than 10% from a lot of threads to another one, can be absorbed in most of the cases by the elastic-lengthening of these threads.

If R were taken as constant, a departure of 110% from the value of X found by calculation would be allowable without departing from the scope of the invention, for the yarns always have some elasticity which can be relied on to absorb slight differences due to an approximate calculation of chain-stitch yarn delivery.

We have, moreover, studied the case where chain-stitch yarns are operative between several columns of stitches. We have presented in FIGURE 3 a binding combination in which the chain-stitch thread is operative between two columns or wales of stitches M and M separated by a wale of the stitches M this chain-stitch yarn 5 acting then as a weft thread. (We must note therefore, that we can provide other weft threads without knitting such as threads 3). It is then necessary to add to ratio X above-mentioned a correction term X corresponding to a supplementary weft running ofthread 5 and given by the following approximate formula:

in which letters R, M have the s me meanings as a and n=number of columns of stitches separating the two wales between which the chain-stitch thread is operative,

J gauge of used knitting machine in needle number per an English inch.

Therefore, it is possible to generalize the application of the process according to the invention to all binding combinations that can be used to obtain such cloths.

After thermo-setting the fabric stays as it is. Any stretch left is only due to the natural elasticity of the components, which balance the relative inexact factor R.

The formula may lead to the fabric as knitted having relativelycorrugated yarns 4, but these disappear after shrinkage, since shrinkage converts thewales 1 into complexs which are of similar appearance to twisted yarns without mechanical elongation and which subsequently behave like theyarn 4; indeed, the latter can be a twisted yarn and is therefore straight.

I claim:

1. A method of producing knitted fabrics having a repetitive pattern and having the appearance and properties of woven fabrics, comprising feeding a first yarn which can be shrunk and which can be set after being shrunk and forming rows of stitches therefrom, assembling said rows of stitches by means of two yarns which act as weft yarns and join at least two rows of stitches, feeding straight yarn, which shrinks less than the first yarn and inserting such straight yarn in unknitted condition between the rows of stitches, controlling the rate of feeding of the first yarn relative to the rate of feeding of the straight yarn so that the first yarn has a length which markedly exceeds the length of the straight yarn and which is substantially equal to the theoretical length of the first yarn which is required to obtain an inextensible row of stitches after the shrinkage treatment, subjecting said fabric to a shrinkage treatment, and during the shrinkage treatment maintaining the length of the fabric substantially equal to the length of the straight filling yarn after allowing for any shrinkage of the filling yarn.

2. A method of producing knitted fabrics having a repetitive pattern and having the appearance and properties of woven fabrics, comprising feeding a first yarn which can be shrunk and which can be set after being shrunk and forming rows of stitches therefrom, assembling said rows of stitches by means of two yarns which act as weft yarns and join at least two rows of stitches, feeding straight yarn, which shrinks less than the first yarn and inserting such straight yarn in unknitted condition between the rows of stitches, controlling the rate of feeding of the first yarn relative to the rate of feeding of the straight yarn so that the first yarn has a length which markedly exceeds the length of the straight yarn and which is substantially equal to the theoretical length of the first yarn which is required to obtain an inextensible row of stitches after the shrinkage treatment, and subjecting said fabric to a shrinkage treatment, and during the shrinkage treatment maintaining the length of the fabric substantially equal to the length of the straight filling yarn after allowing for any shrinkage of the filling yarn, the ratio X of the delivery of the yarn used to form a single row of stitches to the delivery of the filling yarns being given by the formula:

N metric number of this same yarn when knitting,

R shrinkage of the chain-stitch yarn relative to the filling yarns, that is to say, the complement to unity of difference between the shrinkage of the stitch forming yarn and of the filling yarn, and

M=number of stitches required per unit of shrunk fabric length.

References Cited by the ExaminerUNITED STATES PATENTS 5 FOREIGN PATENTS 455,574 3/1949 Canada. 1,242,314 8/1960 France.

565,580 11/1944 Great Britain.

MERVIN STEIN, Primary Examiner. ROBERT R. MACKEY, Examiner.

R. FELDBAUM, Assistant Examiner.

Claims (1)

1. A METHOD OF PRODUCING KNITTED FABRICS HAVING A REPETITIVE PATTERN AND HAVING THE APPEARANCE AND PROPERTIES OF WOVEN FABRICS, COMPRISING FEEDING A FIRST YARN WHICH CAN BE SHRUNK AND WHICH CAN BE SET AFTER BEING SHRUNK AND FORMING ROWS OF STITCHES THEREFROM, ASSEMBLING SAID ROWS OF STITCHES BY MEANS OF TWO YARNS WHICH ACT AS WEFT YARNS AND JOIN AT LEAST TWO ROWS OF STITCHES, FEEDING STRAIGHT YARN, WHICH SHRINKS LESS THAN THE FIRST YARN AND INSERTING SUCH STRAIGHT YARN IN UNKNITTED CONDITION BETWEEN THE ROWS OF STITCHES, CONTROLLING THE RATE OF FEEDING OF THE FIRST YARN RELATIVE TO THE RATE OF FEEDING OF THE STRAIGHT YARN SO THAT THE FIRST YARN HAS A LENGTH WHICH MARKEDLY EXCEEDS THE LENGTH OF THE STRAIGHT YARN AND WHICH IS SUBSTANTIALLY EQUAL TO THE THEORETICAL LENGTH OF THE FIRST YARN WHICH IS REQUIRED TO OBTAIN AN INEXTENSIBLE ROW OF STITCHES AFTER THE SHRINKAGE TREATMENT, SUBJECTING SAID FABRIC TO A SHRINKAGE TREATMENT, AND DURING THE SHRINKAGE TREATMENT MAINTAINING THE LENGTH OF THE FABRIC SUBSTANTIALLY EQUAL TO THE LENGTH OF THE STRAIGHT FILLING YARN AFTER ALLOWING FOR ANY SHRINKAGE OF THE FILLING YARN.

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