This invention relates to a method and a device for producing knotted yarn from spin-textured filament yarn in a continuous yarn channel of an interlacing nozzle with a main bore directed centrally at the yarn channel axis for the primary air and at least one auxiliary bore at a distance from the main bore for secondary air.
Knotted yarn is produced for various fields of use by an air interlacing process: very large titers such as those used for BCF yarns, fine yarns for textile titers or for smooth yarns. The individual filaments of a smooth or textured filament yarn are tied together by means of interlaced spots. The goal of this treatment is to achieve better processability, e.g., in bobbin draw-off, weaving or knitting without expensive twisting operations or smoothing processes. The compactness of the thread of the tangled yarns is created by means of interlacing nozzles. One particular advantage of these nozzles is that they are functional even at the full production speed of spinning, drawing and stretch-texturing processes. They may therefore be used in-line in these processes as the least expensive elements. The core part of an interlacing nozzle is the yarn channel with a transverse bore for the supply of compressed air.
On the basis of model concepts so far, the filament structure of the running thread is opened in the manner of a bubble by the air stream through the transverse bore. Due to the substream eddies, the filaments at the right and left of the transverse bore within the yarn channel are set in rotation in opposite directions. This results in interlaced filaments, referred to as interlaced spots and/or knots, upstream and downstream from the air bore. When the interlaced spot leaves the air stream, the relative movement of the individual filaments is stopped due to the interlacing. Then unbraided filaments are continuously entering the nozzle due to further conveyance of the thread. Then the process begins from the beginning. Therefore, the formation of knots is a discontinuous process.
The object of interlacing is to achieve compactness of the thread, i.e., better cohesion of the individual filaments. The interlacing quality is evaluated on the basis of the three criteria: interlacing density, interlacing uniformity and interlacing stability. The most commonly used method of evaluating the quality of interlacing is to measure the average number of interlaced spots per meter. However, this method says little about the individual distances between the interlaced spots. The standard deviation of the interlacing density on the basis of several measurements also does not provide any relevant information regarding the interlacing uniformity. However, if the open lengths are measured, one need only determine the minimum value (Ölmin.) and the maximum value (Ölmax.). The test results Ölmin. of 0.6 cm to 1.3 cm means that all the distances between the interlaced spots are within 0.6 cm to 1.3 cm. This is a very precise statement of quality and it is not even necessary to state the number of interlaced spots per meter.
The third important quality criterion is the interlacing stability. Interlacing must withstand the thread tension forces that occur during processing with regard to the compactness of the thread, i.e., the interlaced spots must not become uninterlaced during processing. However, so-called hard interlaced spots are more visible in the textile structure than soft interlaced spots. Therefore, the interlacing stability is preferably adapted to the given use, i.e., the material is selected to be only as hard as is necessary. A good statement regarding the use-specific interlacing stability is obtained with a load series in which the interlacing density at a corresponding yarn load is measured and compared with the basic load results.
Over the course of development work it has been found that with the help of the interlacing technique it is possible to combine a much larger spectrum of different yarns. First, existing twisted “multicomponent classics” can be substituted while on the other hand completely novel yarn combinations tailored to meet certain needs can be produced. Almost all types of filament yarn can be interlaced together with other filament yarns, polyarnide, polyester, polypropylene, viscose, acetate, etc. if at least one component meets certain prerequisites with regard to the fineness ratio and bending strength.
Three basic types of air interlacing nozzles are distinguished: the closed nozzle, the open nozzle with a threading slot and a mixed type of the two, the open/closed nozzle. In the case of the closed nozzle, the yarn must be drawn into the nozzle by means of intake air with appropriate threading aids for threading it through. The open nozzle has a threading slot that is open continuously so that even the running yarn can be threaded in by hand. The open/closed nozzle has mechanical movable means. The nozzle is usually designed in two parts, with one part having the compressed air supply being fixedly mounted on the machine. The second part is the movable part and is either brought into the open position for the threading or into the closed position for the normal production operation. The open nozzles like the open/closed nozzles are usually designed in two parts and preferably have a planar baffle surface in addition to the threading slot in the part opposite the air supply. The baffle surface plays an important role in the interlacing function. The closed nozzle has become less important in comparison with the two other basic types.
The process speed, especially in the production spin-stretch-textured carpet yarns, has increased in recent years from approximately 2000 m/min to 3500 m/min. For spin-stretch machines, a speed range of 4000 to 6000 m/min or more is the goal. Since interlacing occurs in-line after texturing but before spooling, the goal of working optimally without a loss of quality with a yarn transport rate of 3000 to 6000 m/min, for example, also applies to the interlacing nozzles. The interlacing nozzles used for textured yarns usually have a blasting air channel which is at a slight inclination in relation to the conveyance direction of the yarn. The inclination from the vertical is usually 10° to 15° and yields a slight conveyance effect for the yarn passing through it, but that is lower than the sum of the resistance forces counteracting the yarn in the nozzle. At higher inclination values of the blasting nozzle, i.e., when there is a greater conveyance effect, however, the interlacing efficacy declines accordingly and the loopiness of the yarn increases. Another consequence of the interlacing at high speeds is the need to increase the air pressure. This results in a higher density of the air in the yarn channel. At high process speeds, one would like to achieve an interlacing density and interlacing quality that are as similar as possible to those obtained at low process speeds in order to ensure further processing of the yarn uniformly. Experiments have shown that the thread tension at the nozzle outlet achieves an ever greater percentage increase value in comparison with the input thread tension with an increase in the yarn speed and with a higher air pressure of the blasting nozzle at the same time. At 4000 m/min, an output thread tension with a value of 120 to 160 is obtained when the initial thread tension has a value of 100. However, a 20 to 60% increase is very harmful for the yarn.
European Patent 0 326 552 describes an open/closed nozzle having a slightly inclined angle for the injection of air. An important aspect is the expansion of cross section from the air injection site in both directions to the inlet and outlet of the yarn channel. European Patent 0 465 407 proposes an approximately constant cross section while German Patent 197 00 817 proposes an expanding cross section.
An interesting nozzle design is proposed with German Patent 41 13 927 which relates to a closed nozzle having a planar baffle surface on the side opposite the air injection. Secondary air is also injected tangentially into the yarn channel in addition to the air injection as primary air. German Patent 41 13 927 classifies an air stream as “direct,” i.e., striking the thread at a right angle, “indirect,” i.e., striking the thread obliquely at a certain angle or “pulsating,” i.e., the air is supplied in surges. The air stream is always at the center of the yarn channel. The interlacing fluid, mainly air, is often directed at a very specific angle onto the thread, thus achieving a certain conveyance effect. Especially in processing BCF yarns which are used in carpeting and have a dtex of up to 6000, clean interlacing is often impossible because the air supply is not sufficient. Very high operating pressures and large quantities of air accordingly are hardly able to remedy this situation. German Patent 41 13 927 is based on the object of developing an interlacing nozzle that will achieve a high degree of cleaner interlacing and will also reduce air consumption. An interlacing nozzle has been proposed, mainly for processing BCF yarn, with an interlacing air channel running toward the yarn at a certain angle, with two other support channels having a reduced diameter in comparison with the main channel and being arranged in such a way that the air jets passing by the yarn on the right and left envelop the yarn. Depending on the thread travel in relation to the direction of travel of the yarn, the support channels are situated above or below the main channel. It is interesting that all experiments by the present applicant with the embodiment in accordance with German Patent 41 13 927 have not yielded any advantages with regard to an improvement in knot formation.
The object of this invention is to provide a novel method and a novel device with which a high knot quality can be achieved specifically by having an influence on possible basic parameters of interlacing even at higher yarn conveyance speeds.
The inventive method is characterized in that the primary air is supplied into the yarn channel at a right angle or at only a low rate of conveyance and the secondary air is supplied through the at least one auxiliary bore in support of the eddy current and with a conveyance effect.
The inventive device is characterized in that the main bore is arranged perpendicular to the yarn channel axis or at a slight angular deviation for or against a slight conveyance effect onto the yarn and the auxiliary bore(s) is/are inclined to the axis of the yarn channel and is/are arranged to be directed in various ways that are different from the primary air.
The fact that all attempts with auxiliary bores directed at a right angle at the yarn channel have not yielded any improvements at all is of interest. However, a slight inclination, especially in the direction of conveyance but to some extent also opposite the direction of conveyance has yielded surprising improvements. Furthermore, it has been found that the same alignment of the main bores and the auxiliary bores, e.g., in accordance with WO99/19549 has also failed to yield any improvement.
In larger experimental series, the results obtained according to German Patent 41 13 927 as well as the novel invention have been compared. The result was surprising inasmuch as almost no improvement was discernible with embodiments according to the teaching of German Patent 41 13 927 in comparison with the relevant related art. However, experimental results with this novel invention have yielded a number of improvements:
This novel invention allows in particular three positive effects, namely:
The best results were obtained with interlacing nozzles having bent yarn channels.
This novel invention allows a number of particularly advantageous embodiments. Reference is made in this regard to claims 2 through 7 and 9 through 13.
The novel design is explained in greater detail below on the basis of the state of the art with a few exemplary embodiments, which show:
a a view of an interlacing nozzle in the axial direction in the interlacing channel;
b the flow pattern in the area of air injection;
a a longitudinal section through the interlacing channel of a design according to the state of the art;
b a section IVb-IVb from
c a section IVc-IVc from
a and 5b together show the results of a model calculation of the flow in an interlacing nozzle known in the state of the art;
a and 6b show the results of a model calculation of the flow in an inventive interlacing nozzle according to
a a section along line VIIa-VIIa in
b a section along line VIIb-VIIb in
c a view of
d a view of
e a view of
f a view of the air bore from
a a slide jet designed with the yarn channel open/closed;
Reference is now made to
a, 4b and 4c show a proposal for another embodiment of a known two-part interlacing nozzle. Reference is made in this regard to WO99/19549. The open position must be adjusted by moving the upper nozzle body 20, as indicated with arrow 22 and joint 23. In other designs known in the state of the art, the upper nozzle body 20 is rotated or shifted with respect to the lower nozzle body 21 to open the yarn channel 3.
a and 5b show the results of a model calculation of an interlacing nozzle according to the
This novel invention proposes a supply of primary air and secondary air, as explained below on the basis of
When the results in
a through 7e show the nozzle shape with which large series of experiments were conducted, and which was also selected as the basis for the model calculations according to
a shows an embodiment with a yarn channel that can be opened for threading and closed for operation. Reference is made to WO97/11214 with regard to the design embodiment.
According to another advantageous embodiment, it is proposed that the distance A1 between the auxiliary bores and/or between the auxiliary bores and the main bore in the direction of the yarn channel shall amount to at least 1½ times the diameter D of the main bore. The transverse dimension D of the main bore is preferably oval and is smaller than the corresponding width dimension D of the yarn channel so that an edge distance of 0.1 to 0.5 mm remains between the outer edge of the main bore and the yarn channel width, with the auxiliary bore(s) being arranged in the area of the edge distance. The secondary air here acts mainly outside of the main zone of action of the primary air and is thus able to maximize the positive effects described in the introduction, namely
| Number | Date | Country | Kind |
|---|---|---|---|
| 1794/01 | Sep 2001 | CH | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CH02/00540 | 9/27/2002 | WO | 00 | 9/13/2004 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO03/029539 | 4/10/2003 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3474510 | Torsellini | Oct 1969 | A |
| 3571868 | Buzano | Mar 1971 | A |
| RE28254 | Buzano | Nov 1974 | E |
| 4188692 | Pike | Feb 1980 | A |
| 4245378 | Price | Jan 1981 | A |
| 4575999 | Anahara et al. | Mar 1986 | A |
| 6112386 | Weinsdorfer et al. | Sep 2000 | A |
| 6134759 | Saijo et al. | Oct 2000 | A |
| 6311376 | Hinchliffe et al. | Nov 2001 | B1 |
| 6438812 | Jansen | Aug 2002 | B1 |
| 6609278 | Ritter et al. | Aug 2003 | B1 |
| 6834417 | Buchmuller | Dec 2004 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20050011061 A1 | Jan 2005 | US |