MXPA96004760A - Process and apparatus for knitting by fabric points with non elastic wire and nude elastomeric wire, and woven fabric constructions per point for suete - Google Patents

Abstract

The present invention relates to a knitted fabric, for sweaters, containing hard braided yarn together with bare elastomeric yarn. The elastomeric yarn has substantially uniform stretching along each row in the fabric. The fabric is made by a process in which the bare elastomeric yarn is fed under substantially uniform tension to a knitting machine, in which yarn disbalance fluctuates as the fabric is woven. The knitted fabrics, for sweaters, are useful in the manufacture of garments such as sweaters, vests, dresses, pants, skirts, shirts and hats.

Description

PROCESS AND APPARATUS FOR KNITTING BY FABRIC POINTS WITH NON-ELASTIC WIRE AND NUDE ELASTOMERIC WIRE, AND WOVEN FABRIC CONSTRUCTIONS BY SWEATER POINTS BACKGROUND OF THE INVENTION This invention relates to the fabric knitted by stitches from non-elastic threads and elastic threads. More particularly, this relates to the knitted fabric for sweaters made of hard yarn braided with bare elastomeric yarn. Knit-woven fabrics, constructed by braiding hard yarns, such as nylon, wool, cotton and polyester, with processed elastomeric yarns, such as yarn with filament web and short fiber wrap, elastomeric, covered elastomeric yarn, or yarn Teslanized elastomeric, are well known. Such fabrics are typically prepared either by knitting two yarns together, or by braiding the elastomeric yarn and the knitted structure formed by the hard yarn. Processed elastomeric yarns are less than desirable for use in sweaters and other REP: 23338 knitted outerwear, as these are expensive to prepare and involve difficulties in subsequent garment manufacture, such as color disparities by the threads that cross the fabric, irregular stitching, and excessive weight. Knitted fabrics, constructed by braiding hard yarn with bare elastomeric yarn, such as spandex, are known, and overcome some of the above problems. However, such knit fabric constructions by methods known from the prior art result in knitted fabrics that show a number of undesirable conditions, such as broken spandex filaments, barred, uneven lengths of selvedges, and clogging of fabrics. the stitches. This, in turn, results in lower quality of the fabric woven by points and waste. In addition, any variation in the speed of the elastomeric fiber fed will induce the variation in tension and stretch of the spandex or elastomeric yarn, resulting in changes in the dimension of the finished garment. In European Publication No. 0119536 owned by Bayer AG of Germany, a method is described for jointly weaving spandex or elastomeric yarn with hard yarn in which the feeding of the elastomeric yarn is controlled by means of a tension device based on friction, which operates to frictionally constrain the elastomeric wire fed. The method described in this publication is disadvantageous because the tension of the fed yarn is extremely difficult to control in a uniform manner - the yarn is intermittently grasped and released as it is being fed for knitting by stitches. This leads to uneven and uneven fabric laps and width formation, in the final product that is produced by this method. Accordingly, it may be desirable to provide a system method that overcomes the disadvantages found in the prior art.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a knitted fabric for sweaters, comprising at least one hard yarn and at least one bare elastomeric yarn, the yarns being braided together into a knitted fabric for sweater, wherein the elastomeric yarn has substantially uniform stretch along each row on the fabric.

In addition, the present invention provides a method for constructing a knitted fabric for sweaters, comprising: distributing at least one bare elastomeric yarn and at least one hard yarn at a common site for knitting; knitting together the two threads in a braided formation, in order to produce a knitted fabric for sweater; the selection of a desired level of tension for the elastomeric yarn, as the yarn is distributed for weaving by points; and the maintenance of said desired level of tension, substantially constant during weaving by points, such that the tension of the elastomeric yarn during weaving by points in the state of rest varies no more than 17% of the tension of said yarn in the state in total rest, average. In addition, the present invention provides a system for building knitted fabrics for sweaters by braiding together at least one hard yarn and at least one bare elastomeric yarn, comprising: a means for knitting together at least one elastomeric yarn and stitching together. at least one hard thread in a braided formation, in order to produce a knitted fabric for sweaters; means for distributing the elastomeric yarn to the knitting means; means for distributing said hard yarn to the dot weaving means; means for selecting a desired level of tension for the elastomeric yarn, as the yarn is distributed towards the knitting means; and Q a means for maintaining the desired level of tension, substantially constant during weaving by points, such that the tension of the elastomeric yarn in doubt weaving by points in the state of rest varies by not more than 17% of the tension in state of rest total, average, of said thread.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of 2Q a system useful in the practice of the invention, including a spandex feeder or elastomeric fiber, in operation with a knitting machine.

Figure 2 is a perspective view of the feeder of the elastomeric fiber described in Figure 1.

Figure 3 is an enlarged perspective view of one embodiment of a support assembly for winding wires, for practicing the invention.

Figure A is an enlarged side view of the support for winding elastomeric yarns described in Figure 3.

Figure 5 is a perspective view illustrating a second embodiment of a wire carrying assembly for practicing the invention.

Figure 6 is a cross sectional view of the lower arm and the tip of the bobbin holder, of the bobbin holder mounting assembly described in Figure 5.

Figure 7 is a front view of the tip and the guide wheels of the thread-winding support described in Figure 6.

Figure 8 is a cross sectional view showing in more detail a first embodiment of the guide wheel assembly at the tip of the bobbin holder of Figures 5-7.

Figure 9 is a cross sectional view showing in more detail a second embodiment of the guide wheel assembly at the tip of the bobbin holder of Figures 5-7.

Figure 10 is a front view of another embodiment of a tip of the thread-wrapping support, for practicing the invention. 1 Figure 11 is a side view of the tip of the bobbin holder of Figure 10.

Figure 12 is a cross sectional view of the tip of the bobbin holder of Figure 11, taken along line 12-12. This view shows the tip of the bobbin holder and the thread guide located inside the tip.

Figure 13 is a cross sectional view of the wire guide of Figure 12.

Figure 14 is a perspective view of the tension device for the hard yarns in the knitting machine described in Figure 1.

Figure 15 is a graph of the stretching of the elastomeric spandex fiber versus the position along a row in a knitted fabric made according to this invention, as compared to a fabric made according to the prior art.

Figure 16 is a plan view of the side-of the technical back of a piece of fabric made according to the invention.

DETAILED DESCRIPTION OF THE INVENTION Generally speaking, the present invention provides a knitted fabric, for sweaters, that has substantially uniform stretch despite intermittent or fluctuating demand for the yarn during the weaving process. The invention also provides a method and apparatus for making such a knitted fabric for sweaters, by feeding bare elastomeric yarn to a knitting machine substantially under uniform tension. For purposes of this invention, "knitted fabric for sweaters" is a fabric that is knitted by stitching on a circular strip knitting machine or a flat strip knitting machine. These strip weaving machines insert a strand or separation yarn between the woven strips and / or knit a finished edge, for example a wrist band or a cuff, at the beginning of the sweater strip. The finished edge generally has a different stitch construction than the rest of the strip. In such strip weaving machines, the demand for the yarn, including the bare elastomeric yarn, is intermittent or fluctuating, regardless of whether the machine is automatically controlled (eg, mechanically or electrically controlled) or manually controlled. The intermittent demand results from the periodic inversion of the support for winding yarn in the fabric by flat points and from the crossing from one strip to the other in circular weave. The fluctuation demand results from the changes in the construction of the stitch, which can be between rows, as in the change between the body of the strip and the finished edge, or within a row, as in the construction of alternating rib / smooth point or "jersey. sweaters, can be used in various garments including, but not limited to, sweaters, vests, dresses, pants, shirts, skirts and caps The precise and uniform control of stretching (lengthening) of elastomeric yarn when weaving a woven fabric by stitches for sweater, it is critical to overcome the problems noted above in the present.This is particularly important when the yarn stretch is modest, for example, less than 4.5 elastice (elongation of 350%) average, throughout a This is because the elastomeric yarn that has low stretch will show noticeable dimensional differences or inconsistencies if the yarn tension varies as it is fed to the yarn. the knitting machine. When the yarn tension is kept substantially constant during weaving, the yarn feeding speed adjusts to the momentary demand for the elastomeric yarn by the knitting machine, and can be achieved by stretching substantially uniformly along the elastomeric yarn. Substantially constant tension levels can be achieved during weaving by periodically checking the yarn tension and adjusting the feed speed accordingly, and by eliminating or reducing the friction sources applied to the elastomeric yarn, according to this one. it is fed to the knitting machine. The bare spandex is the elastomeric yarn to be used in the method and product of the invention. Naked spandex is known to have a high coefficient of friction, and is defined as a filamentous fiber manufactured in which the substance forming the fiber is a long chain synthetic polymer composed of at least 85% by weight of a segmented polyurethane. It will be apparent, however, that the product-and the process of the present invention can incorporate and use any elastomeric fiber, such as rubber or polyetherester fiber, which has suitable properties for knitted fabrics for sweaters and knitting such fabrics. The bare elastomeric yarn has an average stretch along a row of knitted fabric preferably 4.5x in elasticity (elongation of 350%), more preferably l.lx to 4.5x in elasticity (10% at 350% elongation) and more preferably from 1.2x to 2.5x of elasticity (20% to 150% elongation). The stretching of the bare elastomeric yarn is substantially uniform along each row in the knitted fabric for sweaters. That is, said stretching varies by less than about 10% from one side of the fabric to the other, along the row. Furthermore, it is desirable for the stretching of the bare elastomeric yarn, that it be substantially uniform in the successive rows in the fabric. In other words, it is desirable for the stretch of each row to vary by 8% or less of the stretching of each other row in the fabric. More preferably, the variation in said stretching is less than 5.5% along each row and in the successive rows. The bare elastomeric yarn having a denier between 10 and 150 is advantageous for this invention. The bare elastomeric yarn having a denier between about 10 and 70 is more advantageous. The control of the tension level of the elastomeric yarn, such that the yarn feed speed is adjusted to the demand for said yarn in the knitting machine, is achieved by the use of a process and a feeding apparatus that supplies the yarn of uniformly, while compensating intermittent demand or fluctuations in demand. The tension level of the elastomeric thread can be controlled in the fabric in points by flat and circular strips, in part, by incorporating in the yarn distribution apparatus, a means for detecting momentary variations in demand for the elastomeric yarn, and a means responsive to the sensor means, to control any variation in the tension level of the yarn. Elastomeric yarn as the level of tension tries to vary in response to variations in yarn demand. Any mechanism capable of detecting variations in elastomeric thread tension can be used as the sensor means. Such mechanisms include optical, electronic, variable electrical resistance, mechanical devices and voltage indicating devices (for example a piezoelectric pressure (voltage) sensor). A moving mechanical control arm or a voltage measuring device is preferred. The sensor means may provide a signal to the drive mechanism of the yarn feeder, indicating whether the feed speed of the elastomer yarn needs to be adjusted. Alternatively, the sensor means can provide a signal to a device in the wire path, which can pick up the wire to increase the voltage level. The reduction of friction along the feed path of the yarn of the knitting machine further improves the uniformity of the elastomer yarn feed. Such friction can be reduced by replacing as many stationary guides as possible, with stationary guides having low friction surfaces, such as ceramic, sapphire or ruby guides whose surfaces have been polished, or with rotating guide members, preferably wheel guides that rotate inside the jewel bearings (for example, sapphire). In addition, the removal of obstacles, including fixed guides, in the elastomeric wire path, can help reduce the need for such guide members. The process and apparatus of this invention maintains the tension level of the elastomeric yarn, substantially constant, such that the tension of the elastomeric yarn during weaving in a state of rest varies by about 17% or less, preferably 10% or less, more preferably 6. % or less, of the tension in total, average, state of the thread. Such tension control of the elastomeric yarn produces knitted fabric for sweaters, in which the elastomeric yarn has substantially uniform stretch along it, such that the cloth has substantially uniform stretch, recovery and weight per unit area. For a more complete understanding of the invention, reference is made to the following description of the preferred embodiments, and of the accompanying drawings describing such embodiments. The embodiment chosen for purposes of illustration, as shown in Figures 1-14, is a dot weaving system, which includes a supply unit 9 for spandex or other elastomeric yarn, as described in the US Patent. No. 4,752,044, which is incorporated by reference herein, and a flat-bed knitting machine, generally indicated at 10, for knitting with a hard yarn. As shown in Figure 1, the spandex supply unit 9 includes a spandex feeding device, generally indicated at 14, which is mounted on a platform 16. The spandex yarn 18 is fed from a bundle 19 of yarn spandex to the feed device 14, which is designed to provide the yarn 18 to the knitting machine 10 at a substantially uniform tension and draw. As best seen in Figure 2, the spandex yarn 18 is led through a thread guide eye 30, in order to guide the spandex through a stop-movement arm (not shown), which detects the breaking of the spandex. thread, and then on a storage spool 32. The feeding device 14 also includes a yarn tension sensor 34 and a guide roller 36, on which the yarn 18 travels from the storage reel 32, carrying one or more turns of the spandex thread 18, as it is fed to the knitting machine 10. The detection is achieved by a control arm 38 on which the roller 36 is mounted. The control arm 38 can have its position relative variant depending on the demand for spandex 18 by the knitting machine. The control arm 38 is coupled to an internal motor (not shown) which operates and drives the storage reel 32. The desired level of thread tension is selected by adjusting the tension adjuster 53 of the wire, the device 14 The tension level can be programmed to change during weaving, if desired, or to remain constant. When the demand for spandex increases, the control arm 38 moves in a clockwise manner. This increases the speed of the internal motor, which in turn increases the rotational speed of the storage reel 32, and therefore increases the feed speed of the yarn. If the spandex demand decreases, or stops completely, the process is reversed, and the control arm 38 moves counterclockwise until the spool 32 moves slowly or becomes stationary. The knitting machine 10 (by way of example, Model SBO 202 sold by Shima Seiki of Wakayama, Japan) includes two needle beds, as is standard in the technique of flat bed knitting machines, and a lock 12 which travels forward and backward in order to weave horizontal rows of stitches. The lock 12 drives a series of supports for winding yarns, generally indicated at 11 (see Figure 3), to provide yarns to the knitting needles of the machine 10, the knitting machine 10 also includes a support plate 13 on the which are the wire cones 15 for supplying hard yarns. In particular, the yarn cone 15 carries a hard yarn such as nylon, rayon, wool or cotton. The wire carried by the cone 15 is unwound and travels through a standard tension device 17, as shown, which keeps the wire under tension, and also acts as a stop or stop movement, which is activated if the thread breaks. The hard yarn is then brought to a lateral tension device, generally indicated at 20, and shown in the enlarged view of Figure 14. The lateral tension device 20, as is known in the art, includes a plurality of units. of tension devices that are formed in rows to carry a plurality of hard yarns through them. A multiple number of hard wires 15 can travel through a corresponding thread guide eyelet 22 of its tension device unit 21, from which the wire is guided towards a corresponding thread guide eyelet 24 of device 20. Hard wire it travels through the tension device 20 to keep the hard thread under tension and to place the thread appropriately as it is supplied to the support 11 of the thread winder, as will be described below. The elastomeric thread or spandex passes from the feeding device 14 (see Figures 1 and 2) directly onto a corresponding wheel 29, and through a window 50 formed in the cover 27. The wheel 29 is horizontally and vertically aligned with the spool 32 of the feeding device 14 (Figure 2) and the wheel 40 mounted on the assembly 11 of the support for winding wire (Figure 3). This substantially reduces the amount of frictional stretching on the spandex yarn 18, as the yarn 18 is carried along it. Returning now to the support assembly for winding yarn, generally indicated at 11 and shown enlarged in Figure 3, a support for winding yarn HA is used to carry the hard yarns 15, while a second support for winding yarn, 11B, is used to carry the spandex thread 18. The support assembly 11 for winding yarn is attached to one or more support blocks 41 for winding yarn, which travels on the rails 61. The spandex thread 18 enters at an angle to the needle of the knitting machine, in comparison to the hard yarn 55, as shown in Figure 3, and is as it is best known in the art. technique in weaving by braiding. Consequently, the spandex is placed on the back or behind the hard yarn, when it is being knitted, so that the spandex is hidden from view when a finished garment is prepared. A second hard yarn can be integrally woven with the first yarn and the spandex either through the use of a third support for winding yarn, separated, or by feeding the two yarns simultaneously through a simple wire spooling support. One of the important features of the system of this invention is the use of a series of low friction surfaces or wheels in various positions of the system to carry the spandex. These are used in order to minimize as much as possible the amount of friction as the spandex thread moves through the system. One reason for the spandex yarn to be worn with a minimum amount of friction is so that the spandex yarn can be woven, if desired, under low tension with the resulting low draw. If the spandex were woven under high tension, a resulting sweater-like garment could have too much elasticity, in other words, the resultant garment acts as a belt and could constrict the wearer's body. This could also make the garment heavier than desired. There is yet another reason why it is important to ensure that the spandex is transported as friction free as possible. If substantial friction existed, then the spandex could be woven in an uneven and discontinuous manner, especially when knitting at low tension points, due to the intermittent stretching of the spandex at each friction point. As a result, the final fabric product could contain stitch distortion, as well as horizontal lines, known as barred. An additional reason to eliminate friction is to prevent, as much as possible, the breaking of the spandex yarn in the finished garment. Excess friction along the spandex yarn can overstress the yarn to a level where breakage in the finished garment can take place. In the specific embodiment described in Figures 2, 3, 4 and 14, there is a series of wheels that can be rotated in numbers 29, 36, 40, 42 and 44. The improvements and alternatives to this modality are shown in Figures 5-13. . In Figure 5, the support assembly for winding yarn is generally indicated at 111, and includes an upper arm 113, a lower arm 115 pi easily connected to the arm 113 by a spigot assembly 117, and a tip 123 of the support for wind the thread. As illustrated in Figure 5, the elastomeric yarn 121 goes over a first wheel assembly 119, where it changes direction by an angle of 90 °. The guide wheel assembly 119 is mounted on the upper arm 113 of the mounting 111 of the support for winding the yarn. The elastomeric yarn 121 continues towards a second second guide wheel assembly, mounted within the tip 123 of the support for winding the yarn, and described later. There, the elastomeric yarn changes direction again at an angle of 90 °, either to the left or to the right, depending on the directional traverse of the mounting of the bobbin holder of the system. Focusing more closely on the lower arm 115 and the tip 123 of the support for winding the yarn, Figures 6 and 7 show the yarn 121 falling between a pair of rotatable wheels 121, each of which is fixed to a corresponding axis 127. As shown in Figure 8, each wheel assembly of the support tip for winding the yarn includes the steel shaft 127, a wheel 125 mounted, fixed, preferably made of Delrin MR acetal resin (DuPont Company, Wirmington, Delaware, E.U.A.), which rotates with the shaft, and a pair of jewel bearings 129 in which the pointed shaft ends up being nested. In the embodiment of Figure 8, a flat spring 131 separates each jewel bearing from the steel housing 133 of the wheel assembly. As a result, the bearings 129 press up against the ends of the steel shaft 127 embedded in the wheel 125. The wire 121 of course, travels on the wheel 125, as shown. A second embodiment of each of the wheel assemblies 124 is illustrated in Figure 9. Instead of using flat springs to push the bearings against the pointed ends of the shaft, the wheel assembly 124 includes a cylindrical propeller spring 135 provided on it to push the elements 127a and 127b of the shaft, in opposite directions against the jewel bearings 129. Significantly, the guide wheel assembly 119, generally illustrated in Figure 5, is preferably constructed in accordance with either the embodiment shown. in Figure 8 or with the embodiment shown in Figure 9. Instead of guide wheels or pulleys, polished, stationary ceramic or jewel surfaces may be used to guide and / or change the direction and / or angles of the naked elastomeric yarn. One modality of a stationary gem guide is described in Figures 10-13. The tip 223 of the support for winding the yarn is hollowed out as shown in Figures 10-13. The jewel ring 219, preferably a sapphire, is placed inside the tip 223 of the support for winding the yarn as shown in Figures 12 and 13. To further reduce the contact points, and thus the friction, as length of the elastomeric yarn, the jewel spring 219 may be countersunk as shown in the cross-sectional view of Figure 13. As can be seen, the aforementioned stationary guides and the wheels carry the spandex yarn along them. . More specifically, whenever the spandex yarn changes direction, including as it is being fed to the knitting needles, it is necessary to have a low friction stationary surface or rotatable wheel applied thereto to eliminate the friction applied along the spandex yarn. , as much as possible. In addition, using two supports to wind the yarn (one for the hard yarn and one for the spandex), as shown in Figure 3, a significant friction point is eliminated. Ordinarily, a simple, standard braiding carrier or bracket is used, which carries the hard and spandex yarn. This type of support will produce substantial friction between the yarns, as the yarns are being fed through the support assembly for winding the yarn, and to the needles of the knitting machine. The use of an individual support for the spandex yarn, as shown in Figure 3, on the other hand, completely eliminates friction between the yarns. In addition, the bracket for winding the spandex yarn is fitted with a separate wheel 40, to further minimize friction, as much as possible. As shown in Figure 4, the bobbin for winding the yarn for the spandex yarn 18 also has rollers 42 and 44 mounted at its end. The spandex yarn is carried from the roller 40 and then threaded between the rollers 42 and 44, in order to minimize any change in tension when the support 11 changes speed while traveling from a feed direction forward, towards a stop (from left to right), and then again changes speed when traveling in a reverse feed direction, in an inverse path (from right to left). To illustrate the present invention, the knitted fabrics for sweaters, coarse cut, modified rib construction / plain knit or jersey were Lycra MR Type 146-C spandex fabrics (DuPont Company, Wilmington, Delaware, E.U.A.) and four ends of 300 denier continuous filament rayon. Figure 15 is a graph of spandex stretch versus position along a row in these sweater fabrics 92, versus a cloth fabric according to the prior art 90. Apart from the low friction modifications described herein , the settings of the weaving machine were identical. The graph clearly illustrates the reduction and substantial uniformity of the stretching of a knitted product according to the invention, as compared to a knitted fabric according to the prior art. In an alternative embodiment, a second platform 16, the spandex feeding device 14, and the spandex yarn package can be placed on the other side of the knitting machine 10, in order to feed a second spandex yarn to the machine, alternating rows with the spandex supplied from the first platform. This requires the use of an additional thread-wrapping support block (not shown) for the second spandex thread 18. In operation, the support block for winding thread, for the first spandex thread, is carried in a first direction as length of the machine, in order to weave a first row. Subsequently, the support block for winding yarn for the second spandex yarn, is carried in the opposite direction in order to weave a second row. A first block for yarn support is then carried in a reverse direction, and the same for the second support block for winding the yarn. The supply of the spandex for the weaving is thus alternated row by row. As a result of such alternating side feeding, any residual non-uniformity in the stretching of the elastomeric yarn along each row is balanced by an opposite non-uniformity in the next row. In this way, differences in edge length of less than about 7% are achieved, and uneven edge lengths are substantially avoided. In the test, when a simple spandex thread and a hard thread (rayon / spandex) were fed to the weaving machine, adjusted with the low friction guides, the selvedge of the fabric opposite the side from which the spandex was fed, , was on average 20% longer than the side closest to the spandex supply. The coefficient of variation (the measure of the amount of irregularity) of the edge length was on average 10.0%. When the spandex was instead fed in alternate rows from both sides of the machine, it was found that the selvedge of the fabric opposite the side from which the spandex was fed was ± 2% longer / shorter than the side closest to the spandex supply. The coefficient of variation of the length of the fabric from side to side, was 2%. This shows that the alternating elastomer yarn supplied row by row is even more advantageous than just using the basic system. The jersey knit fabrics, of rough cut in j-ersey knit construction, were also made of Lycra MR Type 146-C spandex and two 16/2 carded cotton ends. The number of spandex breaks per sample and the complete appearance of the fabrics (based on a rating of 1 (poor) to 5 was determined.

(Excellent). The spandex was fed from one side.

The results are presented in Table 1 below.

TABLE 1 SYSTEM OF FOOD BASE WEIGHT ROTURAS OF THE RATING FROM DEL SPANDEX g / m 'SPANDEX APPEARANCE Without feeder 712.02 26 1 Feeder with 678. 11 15 2 high friction Feeder with 508.60 low friction Where no feeder was used, the spandex was driven from a package on the platform plate, just as with the hard thread. Where a feeder was used, the tension adjustment on the feeder was kept constant. As can be seen, when operating the feeder under low tension, the resulting fabric has a low fabric weight per unit area, and fewer thread breaks. To further illustrate the present invention, the simple knit sweater primordia of knitted fabric for sweaters were woven in a Shima flatbed weaving machine Model SES 122FF (Shima Seiki) so that the technical face was upward. Except where the observation is made, the speed of the machine was 0.75 meters / second, and the feeding of the thread on each needle was 9.91 mm. Simple system knitting was used (one row at a time). The two thread carriers, one for the spandex and one for the hard thread, were used when the spandex was fed from one side of the machine. (Four wire supports were used when the spandex was alternately fed from both sides of the weaving machine). The spandex was a 40-denier single-end Lycra MR (44 dtex) Type 146C, and the hard yarn was four 300 denier rayon ends (330 dtex) (Viseóse # 5330, Fabelta Industries, Ghent, Belgium), which had been reel dyed in black coils. During the single-side feed, the spandex was fed from the right side of the machine through the feeder, and the rayon was fed from the left side of the machine through a voltage gate. The spandex was wrapped around the spool of thread on the spandex feeder approximately three or four times. After dot weaving, the fabrics were washed with detergent at 21 ° C (70 ° F) for 16 minutes and dried at 57 ° C (135 ° F) for 40 minutes. The sweater primordia were analyzed in various ways to give the results summarized in Table 2. The spandex content was calculated as the proportion of spandex denier (in the stretched on the fabric) to the total denier of the yarn in the fabric. The weight of the fabric was calculated from a punch of 7.6 cm (3 inches) in diameter. To evaluate row-to-row stretching uniformity, full-row stretching was calculated by removing the rayon and spandex from that row and taking the ratio of rayon length to that of relaxed spandex. This was done in the upper (T), central (C), and lower (S) of the sweater primordium. To evaluate the uniformity of spandex stretching along a row, a width of 10 cm of fabric placed 5 cm (2 inches) from the bottom (waist band) of the sweater blanket was fastened, cut from the sweater blanket , the rayon and the spandex of a row were removed, and the drawing was calculated as described above; it was removed, and the stretch was calculated as described above; this was done to the left (L), to the center (C), and to the right (R) of the sweater blanket, approximately 5 cm above the bottom of the sweater blanket. To determine the uniformity of the full dimensions of the sweater primordia, the lengths of the selvedges were measured. The sweater primordia were also visually inspected on a black background, the sample numbers being hidden. These were rated for column uniformity, stitch definition, and stitch uniformity on a scale of 1 (poor) to 5 (excellent). The results are reported in Table 2. After each number, and + indicate that the averages of three independent grades were less than or greater than the number reported. During the weaving by points, measurements were made of the stress experienced by the spandex as it left the feeder by passing the spandex through a tensiometer (part No. 006.100.061, Memminger-Iro GmbH, Dornstetter, Germany) and sending the output signal of the tensiometer to a 100 MHz Autoranging device, Tekscope (Tektronix, Wilsonville, 0K) for observation. The tensiometer was the same head normally supplied by Memminger-Iro GmbH with the spandex feeder Model EPS 70. The copies of the strokes were printed from the Tekscope with a Thermal Printer DUP 411 Type II (Seiko Instruments, Chiba, Japan). The maximum tension in grams (g) and grams per denier (gpd), the tension in the State of Rest in grams (g) and the Maximum minus the tension in the State of Rest in grams and in gpd were measured. Here, "Maximum" is the maximum stress applied to the expandex as the support accelerates away from the feeder. "Repose state" is the approximately constant tension achieved after the support increases speed and moves away from the feeder. "Maximum Less State of Rest" is the difference between the "Maximum" and "Rest State" voltages and is a measure of the uniformity of the tension applied to the spandex in the selvage closest to the feeder, in comparison to the rest of the cloth. The greater the difference between the "Maximum" and "Standstill" voltages, the higher the voltage peak as the thread support accelerates.

Example 1 (Comparative Example) The spandex distribution system in this example included a spandex feeder Model EFS 31 (Memminger-Iro GmbH, Dornstetter, Germany) which had been modified by replacing the ceramic "exit wire guide", fixed at the exit of the feeder, with a rotating guide of approximately 1.27 cm (0.5 in) in outside diameter; the feeder tensiometer was set to 0. (The Spandex Feeder Model EFS 31 is similar to the feeder in Figure 2, with the following important differences.) Instead of guide 18 for spandex thread and guide roller 36, the Model EFS 31 is equipped, respectively, with a post and disc tensiometer and an underwire guide eyelet, and instead of the thread 18 traveling freely from the guide roller 36 towards the support assembly for winding threads, the thread exiting the Model EFS 31 passes through a fixed ceramic "exit thread guide" buttonhole). In the weaving machine, a fixed guide was used at the entrance of the "eye board" (the position of the rotating guide 29 in Figure 14) towards the knitting machine. A second rotary guide of 1.27 cm (0.5 in.) In diameter was placed on the top of the spandex support (the same position as the swivel guide 40 in Figure 3) to guide the spandex around the 90 ° tilt and toward down towards the tip finger of the thread bobbin holder (at the bottom of the thread bobbin holder) and the knitting needles; the fixed, customary steel guides were on the tip finger of the bobbin thread holder. The tension on the pole and disc tensiometer at the entrance to the feeder was adjusted as low as possible. The voltage measurements for this system were: Maximum, g 5.2 8Pd 0.13 State of Rest, g 4.0 +/- 0.8 (+/- 20%) Maximum minus Rest State, g 1.2 gpd 0.030 Examples Ha and Hb The spandex distribution system in these examples included the spandex feeder described in Figure 2, wherein a Model EFS 31 feeder, such as that used in Example I, was modified by eliminating the pole and disc tensiometer, replacing the fixed guide on the yarn control arm with a roller guide having an outer diameter of about 8.4 mm (0.33 inches) and mounted on slipped bearings, and removing the guide, fully fixed, guidewire output eyelet. The tensioner of the feeder was adjusted to 0.5. On the dot weaver machine, a roller or roller guide of approximately 12.7 mm (0.5 in.) In diameter was placed on the eye board, and a Delrin MR acetal resin wheel having a plated bearing was placed on the top part of the spandex thread holder. In addition, the fixed guides on the tip finger of the bobbin thread holder were replaced by two small rollers (1.14 mm (0.45 inches) in outer diameter) over the wound bearings, as described in Figures 4-7, spandex traveled over the rollers when the support was moving away and returning to the spandex feeder. In Example Ha the spandex was fed from the right side of the machine by means of an EFS 31 feeder modified as described above. In Example Hb the spandex was fed in alternating rows via two modified EFS 31 feeders from both sides of the weaving machine. The tension measurements for the weaver of Examples Ha and Hb were: Maximum g 3.4 gpd 0.08 State of Rest, g 2.4 +/- 0.1 (+/- 4%) Maximum minus Rest State, g 1.0 gpd 0.025 Examples Illa and IHb In Examples Illa and IHb, the spandex distribution system included an EPS 70 spandex feeder (Memminger-Iro GMbH) in place of the modified EFS 31 feeder. (Using the EFS 70 feeder, the spandex yarn traveled from one coil up and down through an eyelet thread guide wire, around a storage reel (similar to reel 32 of Figure 2), through a first pair of guide pulleys, through a piezoelectric voltage sensing device, and finally over a resin wheel Delrin ^ 1"acetal bearing jewel bearings, which was placed at the exit of the feeder On the storage reel the threads traveled around the reel a few times, then came out at an angle of approximately 90 ° of the track on which the yarn traveled to the reel.) The tensioner of the feeder was set to 4. The rest of the system was the same in Example Ha. In Example Illa, the point weaver was made at a speed of the machine. 0.75 m / second, and in Example IHb, the speed of the machine was 1.1 m / second The voltage measurements for the feeder of Examples Illa and IHb were: Maximum g 2.5 gpd 0.06 State of Rest, g 2.1 +/- 0.1 (+/- 5%) Maximum minus Es tad o de Re p o so, g 0. 4 g pd 0 010 TABLE 2 Each data is based on three measurements on each of the three samples.

EXAMPLE: I Ha Ilb Illa IHb Spandex content,% by weight 1.5% 1.9% 1.9% 1.9% 1.9% Weight of the fabric, g / m2 576.4 406.9 406.9 573.0 406.9 Full-width stretch (measured at the top, at the center, at the bottom) Average 2.0 1.6 1.6 1.6 1.7 Interval in average superior vs. central vs. lower 1.99- 1.61- 1.63- 1.63- 1.65- 2.06 1.62 1.66 1.66 1.67 Maximum Difference Simple Sample 10% 8% 4% 4% 2% Stretched / left / center / right Dif.% Average L / R 12% 5% 0% -1 -1% Edge lengths, difference Left / Right Diff.% Average L / R 10% 10% -1% 2% 2% Range 9-12% 8-12% -2-1% 0-3% 1-3% Average Difference L- *, lcm 4.82 6.86 -0.51 1.02 1.52 Visual Uniformity Rating 1 3- 3- 4 4+ The spandex in the fabric of Examples Ha, Hb, Illa and IHb has a lower and more uniform stretch, either within a row and from row to row, than the fabric of Comparative Example I. In the fabric of the preferred Examples Hb, Illa and IHb, the selvedge lengths are also more uniform. The uniformity of the fabrics of the invention is clearly superior to that of the Comparative Example. Figure 16 is a view of the technical reverse of a piece of cloth made according to the invention. As shown in Figure 16, the hard yarn 55 and the elastomeric yarn 18 are braided together in a putnto construction with the hard yarn that is visible from the technical side, and the spandex that is only visible from the technical back, In this example, the fabric has two portions 67 and 69 defined by rows 68 and 70 respectively, each portion having a different stitch size. As can be appreciated, the sweater knitted fabric shown in Figure 16 has a plurality of needle stitches 71 and placket stitches 73 that are substantially uniform in size and shape in each portion of the fabric. The vertical columns and the horizontal rows are substantially identical also in appearance. The spandex will be stretched substantially uniformly in successive rows and in both portions of the fabric, 68 and 69. As a result, the fabric in both sections will have substantially uniform stretch (through A-A and B-B) and recovery in all sections. addresses . Preferably, the stretching of the spandex will be between 1.1 and 4.5, and more preferably between 1.2 and 2.5. The spandex denier will be between 10 'and 150, more preferably between 10 and 70. The product produced by the method of the invention integrates the bare spandex or some other elastomeric yarn with a hard yarn in a braided knit construction, with In order to produce a fabric knitted by dots, for sweater, uniformly uniform. The fabric will show minimal distortion and increased consistency in size, from piece to piece. According to the prior art, the tension on the spandex yarn increases with the length or the size of the meshes or rovings that are woven. As a result, the stretching of the spandex will also increase. In contrast, in the fabric of the invention, the stretch is maintained at a predetermined and substantially constant level notwithstanding the size of the turn or mesh. This is because the method of the invention makes possible the precise change in the speed of distribution from the spandex to the weaving machine, notwithstanding the speed of the machine or the size or structure of the mesh or spin that is woven. In this way, the spandex is supplied at an elongation or stretching, constant. In addition, because the stretching of the spandex is kept substantially constant, the tactile effect on the fabric is substantially uniform, -the spandex yarn will cause the meshes or turns of fabric to push out uniformly from the plane of the fabric, such that the Hard yarn fibers stretch evenly. Thus, the complete surface of the fabric maintains a uniform and substantially smooth feel. In this way it will be observed that the objectives described above, between those facts apparent from the preceding description and efficiently achieved, and since certain changes can be made in the previous product and in the system without departing from the spirit and scope of the invention , it is intended that all the material contained in the above description and shown in the accompanying drawings, be interpreted as illustrative and not in a limiting sense.

It is also understood that the following claims are intended to cover all the generic and specific features of the invention described herein, and all statements of the scope of the invention as a language subject, may be said to fall within it.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (29)

1. A knitted fabric for sweaters, characterized in that it comprises: at least one hard yarn and at least one elastomeric yarn, the yarns are braided together into a knitted fabric, for sweaters, wherein the elastomeric yarn has substantially uniform stred and along each row on the fabric.

2. The knitted fabric, for sweaters, according to claim 1, characterized in that the elastomeric yarn has substantially uniform streng in the successive rows in the fabric.

3. The knitted fabric, for sweaters, according to claim 2, characterized in that the streis between 1.1 and 4.5.

4. The knitted fabric, for sweaters, according to claim 3, characterized in that stred is between approximately 1.2 and 2.5.

5. The knitted fabric for sweaters, according to claim 1, characterized in that the denier of the elastomeric yarn is between approximately 10 and 150.

6. The knitted fabric, for sweaters, according to claim 5, characterized in that the denier of the elastomeric yarn is between approximately 10 and 70.

7. The knitted fabric, for sweaters, according to claim 1, characterized in that the fabric is a flat knitted fabric.

8. The knitted fabric, for sweaters, according to claim 1, characterized in that the fabric is a circular knitted fabric.

9. The knitted fabric, for sweaters, according to claim 1, characterized in that the bare elastomeric yarn is bare spandex.

10. The knitted fabric for sweaters, according to claim 1, characterized in that the longitudinal difference of the selvedge in the fabric is less than about 7%.

11. A method for constructing a knitted fabric, for sweaters, characterized in that it comprises: the distribution of at least one bare elastomeric yarn and at least one hard yarn in a common position for knitting by stis; knitting together the two threads in a braided formation, in order to produce a knitted fabric, for sweaters; the selection of a desired level of tension for the elastomeric yarn, as the yarn is distributed to the knitting machine by points; and the maintenance of the desired level of tension, substantially constant during weaving by points, such that the tension of the elastomeric yarn during weaving by points in the state of rest varies no more than 17% of the total average tension in the state of rest of said thread.

12. The method according to claim 11, characterized in that during the step of maintaining the tension of the elastomeric yarn during weaving by points in the resting state, it varies by no more than 10% from the average total tension in the resting state. of said thread.

13. The method according to claim 11, characterized in that the maintenance step comprises: detecting the momentary variation in the demand for the elastomeric yarn during the step of weaving by points; and in response to the detection step, the variation in the tension level of said elastomeric yarn is selectively controlled, as said level attempts to vary from the desired level of tension in response to the variations in demand during weaving by points.

14. The method according to claim 11, characterized in that the selection step comprises changing the desired level of tension during the step of weaving by points.

15, The method according to claim 11, characterized in that the step of or weaving by points comprises the weaving by points of the two threads, together in a flat fabric woven by gums.

16. The method according to claim 11, characterized in that the step of weaving by points comprises the weaving of the two threads together into a circular knitted fabric.

17. The method according to claim 11, characterized in that the distribution step comprises feeding the naked elastomeric yarn in said common position in alternating threads, from opposite directions.

18. A system for constructing knitted fabrics, for sweaters, by braiding together at least one hard yarn and at least one bare elastomeric yarn, characterized in that the system comprises: a means for knitting together at least one elastomeric yarn and minus a hard thread in a braided formation, in order to produce a knitted fabric, for sweaters; means for distributing the elastomeric yarn to the knitting means; means for distributing said hard yarn to the knitting means; means for selecting a desired level of tension for the elastomeric yarn, as the yarn is distributed towards the weaving means; and a means for maintaining the desired level of substantially constant tension during weaving by points, such that the tension of the elastomeric yarn during weaving in the idle state, varies by no more than 17% of the average total tension in the idle state of said thread.

19. The system according to claim 18, characterized in that the maintenance means maintains the tension of the elastomeric yarn during weaving by points in the state of rest, at a level that varies by not more than 10% from the average total tension in resting state of said thread.

20. The system according to claim 18, characterized in that the maintenance means comprises: means for detecting momentary variations in demand for the elastomeric yarn by means of said knitting means; and a means responsive to the sensor means for controlling any variation in the tension level of said elastomeric yarn, as the stress level attempts to vary from the desired level of tension in response to variations in yarn demand.

21. The system according to claim 20, characterized in that the sensor means comprises a control arm movable between a first position and a second position, in response to changes in the demand for the elastomeric yarn by said means of knitting by stitches.

22. The system according to claim 20, characterized in that the sensor means comprises a voltage measuring device.

23. The system according to claim 20, characterized in that the maintenance means further comprise wheel means for carrying the elastomeric yarn as the yarn is distributed towards the knitting means by stitches, and being provided at sites where the elastomeric yarn changes substantially in direction .

24. The system according to claim 23, characterized in that the wheel means comprises wheels that travel inside jewel bearings or jewel type.

25. The system according to claim 20, characterized in that the maintenance means further comprises the guiding means for guiding the elastomeric yarn as said yarn is distributed towards the knitting means, the guiding means comprises a low friction surface and it is provided at sites where the elastomeric yarn substantially changes direction.

26. The system according to claim 25, characterized in that the low friction surface comprises a sapphire stone.

27. The system according to claim 18, characterized in that the knitting means comprises a flat bed knitting machine that includes a transport means to selectively transport between one side of the knitting machine and the other side of the knitting machine. Weaving machine by points, in order to weave the fabric.

28. The system according to claim 18, characterized in that the knitting means is a circular knitting machine.

29. The system according to claim 18, characterized in that the means for distributing the elastomeric yarn includes a means for feeding said elastomeric yarn to the knitting means in alternate rows of the yarn supply means placed at either end of the knitter.