Title of Invention	A METHOD AND A TWISTING NOZZLE FOR PRODUCING KNOTTED YARN OR TWISTED YARN FROM DTY-YARN AND/OR FLAT YARNS WITH HIGH REGULARITY OF KNOTS
Abstract	The new invention pertains to a twisting nozzle and a method for producing fine, knotted yarn with a high regularity of the knots, with the help of air nozzles with a yarn treatment channel. The blast air is blown in, transverse to the air treatment channel. The blast air thereby forms a double twist in yarn run direction as well as against the yarn run direction, for generating the knots. For this, it is suggested that the blast air in the inlet region into the yam treatment channel gets converted in a short air twist chamber in yarn channel longitudinal direction into two strong, steady twist flows undisturbed by filament bundles. In spite of the tiny nature of the air twist chamber, which projects max. 0.5 mm or 5% to 22% of the yarn channel width (B) beyond the yarn channel longitudinal wall, the regularity of the knots can be highly improved. It is further possible, depending on the pressure of the blast air, to generate hard or soft knots that get released again.

Title of Invention

A METHOD AND A TWISTING NOZZLE FOR PRODUCING KNOTTED YARN OR TWISTED YARN FROM DTY-YARN AND/OR FLAT YARNS WITH HIGH REGULARITY OF KNOTS

Abstract

The new invention pertains to a twisting nozzle and a method for producing fine, knotted yarn with a high regularity of the knots, with the help of air nozzles with a yarn treatment channel. The blast air is blown in, transverse to the air treatment channel. The blast air thereby forms a double twist in yarn run direction as well as against the yarn run direction, for generating the knots. For this, it is suggested that the blast air in the inlet region into the yam treatment channel gets converted in a short air twist chamber in yarn channel longitudinal direction into two strong, steady twist flows undisturbed by filament bundles. In spite of the tiny nature of the air twist chamber, which projects max. 0.5 mm or 5% to 22% of the yarn channel width (B) beyond the yarn channel longitudinal wall, the regularity of the knots can be highly improved. It is further possible, depending on the pressure of the blast air, to generate hard or soft knots that get released again.

Full Text	Method and Twisting Nozzle for Producing Knotted Yarn The invention pertains to a method for producing knotted yarn or draw twist yarn and/or flat yarns with a high degree of regularity of the knots by means of air jets, with a yarn treatment channel as well as blast air that is blown in transverse to the yarn treatment channel, whereby the blast air forms a double twist for producing the knots in the yarn transporting direction as well as against the yarn transporting direction. The invention further pertains to a twisting nozzle for production of knotted yarn with a high degree of regularity of the knots, with a continuous yarn treatment channel, as well as a blast air feed channel, whereby the blast air feed channel is aligned to the longitudinal central axis of the yarn treatment channel. In the recent past, increasingly finer filaments were produced. These are referred to as microfilaments, if the denier per filament (dpf) lies between 0.5 and approx. 1.2. The yarns thus produced are called microfilament yarns. One refers to them as super microfilament yarns if the dps is below, these include also super microfilaments, unless otherwise mentioned. Already yarns with a dps above 1.2 require careful processing, so that neither the individual filaments nor the entire yarn break. This applies to a greater extent in the case of microfilament yarns. In case of microfilament yarns, the bundle of all filaments has an important significance. Care should be taken that individual filaments do not stray away and hence pose the danger of breaking. DTY-yarns mean drawn-twist-yarn. There is a relatively large use of twisted yarns with so-called air twist in the market. The market indicates two tendencies. In many cases of application, well-structured, strong and stable knots in all degrees of filament fineness are in demand. The air nozzle has to be designed for that with respect to all parameters. The situation is different in case of fine microfilament yarns. With these yarns, fine fabrics are produced that should have a soft and silk-like feel. Here one can see that the formation of very stable and almost unreleasable knots could be disadvantageous, in that the knots leave the mark in an undesirable manner, as a kind of screen, especially on a very fine, single coloured fabrics. Even though knots are desirable within the yarn processing, they should completely disappear later while processing the fine yarns into fabrics or other substances. The so- called knotted yarn is produced by twisting in the twisting nozzle. The knots ensure the local binding of all filaments and short knot sequences over the entire yarn run. The objective of twisting is to achieve a high number of knots per meter with uniform distance between the knots. A yarn treatment channel, with a blast air feed transverse to the yarn channel, provides the device-specific conditions. The blast air flows away on both sides of the yarn channel and on account of the almost centric blowing in the yarn run direction and against the yarn run direction, forms so-called double twists. By taking the yarn through the corresponding twist zone one obtains the kind of alternative air movement that is ultimately co-responsible for a repetitive formation of knots with short interruptions between the knots. The skill lies in finding an optimum solution for the respective application case between the three yarn quality criteria, Knot stability; Number of knots per meter; Regularity of knot formation, with specific designing of all dimensions of the yarn channel of a twisting nozzle, as well as the type of air feeding, air pressure, overfeed and the yarn run velocity. In coarser filaments having dpf 1.2 - 4, a number of up to 110 knots is desirable and in microfilament yarns up to 200 per meter of yarn. The air pressure for microfilaments is approx. 0.5 to 1.5 bar. The overfeed is 3% - 6%. In the state-of-the-art technology, for fine filaments, 140 points or knots per meter of yarn length are generated. The highest possible uniformity/regularity of the knots sequence is thereby desirable. It should be prevented, that knot-free yarn stretches occur, in which one or more knots are successively missing. The extent of stability tells us, under which tensile forces the knots again get released. In the simplest method for testing this, the yarn is held between two hands and stretched slowly or in a jerky manner. The document DE 197 00 817 shows a special form of twisting nozzle for carpet yarn, i.e. for very coarse BCF-yarn. It was based on a method for continuous production of weave-texturized filament yarn in a continuous yarn channel or twisting channel of a twisting nozzle. The filament yarn is twisted by a blast airflow directed in a transverse direction into the nozzle that is flowing forwards and backwards out of the yarn channel and the discharge air of the reversed twist is released in counter-direction to the blast air feed from the yarn feeding region. As solution it is suggested that two twists with different strengths get generated in the twisting channel, whereby the forward twist is designed to be more strongly effective than the reverse twist. The document DE 37 11 759 is based on finer to average yarns and tries to improve the process-ability of the yarn in subsequent processing stages, e.g. in looms, drafting machines and tufting machines. The inventor started off with a twisting device for twisting multi-filament yarns, which have at least one yarn channel, whereby yarn guides are arranged at distances from the inlet and outlet of the yarn channel, and the filaments of one multi-filament yarn can be twisted in the yarn channel by means of compressed air which can be blown in through a blast nozzle. While running into and running out of the yarn channel, the yarn experiences a change in direction of less than 90°, and the blowing angle of the blast nozzle is lesser than 90°. As a new solution, it is suggested that the yarn guides be arranged in such a way, that the yarn is placed through them in such a way on the yarn channel, with the compressed air feed switched off, that it stretches in the yarn channel parallel to its longitudinal direction, and thereby acts at the exit of the at least one blast nozzle. The distance of the yarn guides from their adjacent yarn channel openings is maximum 30 mm. The length of the yarn channel for un-crimped multi- filament yarns is max. 40 mm and for crimped multifilament yam max. 30 mm. The document DE 37 11 759 is useful at least to the extent, that the knowledge of the positive effect of a short yarn channel is useful for producing knotted yarn in a wider specialized world. Concretely, a yarn channel length for texturized or crimped yarns is suggested as 10-28 mm. Especially, the range of 10 mm of yarn channel length is considered as short. Latest experience shows that the actually widespread application of air nozzles for producing knotted yarn is not satisfactory for very fine yarns, particularly in microfilaments. With respect to fine yarns, particularly in microfilament yarns, in any case there is a requirement of maximum regularity of the knot sequence; however, in certain cases of application, only weak, temporarily constant and reversible, i.e. knots that get released again during yarn processing, are required. The knots should not be noticeable in the finished fabrics. It has been attempted several times to operate nozzles of the state-of-the-art technology with lower pressure of the feed air. It is known that with lower air pressure one gets weaker knots, however with the disadvantage of an often not acceptable non-uniformity in the strength or stability of the knots, as well as the distances between the knots. Recently there is very strong tendency in the market to use so-called microfilament yarns. The question of uniformity of the knots, as well as at least an adequate stability of the knots for further processing thereby acquires central importance in many cases of application. In most cases it is required that the number of knots does not fall significantly short of the figure of 140 knots/m that can be achieved at the moment; it is furthermore required that the required pressure for blast air should be reduced, keeping in view the energy consumption. It is now the task of this invention to find a method as well as a twisting nozzle, with the help of which even at high yarn run velocity, the above mentioned quality criteria can be achieved in the production of fine yarns and particularly microfilament yarns, with the following four objectives: - Pressure reduction of the blast air; - Number of knots per meter > 140/m fordpf - Adjustable knot stability; - High uniformity of the knots sequence. The method as per invention has the feature, that the blast air in the entry region into the yarn treatment channel is transferred in an air twisting chamber into two strong, steads air twist flows almost undisturbed by filament bundles. The twisting nozzle as per the invention has a distinctive feature, that in the mouth region of the blast air feed channel in the yarn treatment channel, a blast air channel elongation is formed for creating an air twisting chamber for two opposite steady air twist flows, whereby the blast air channel elongation protrudes by lesser than 22% of the yarn channel width, however more than 5%. With reference to the new invention, two twisting nozzles are known in the state-of-the- art technology: - Firstly, these are twisting nozzles with continuous yarn channels, as described in the introductory part of DE 37 11 759. The typical characteristic thereby is a uniform continuous yarn channel. - Secondly, these are twisting nozzles with a yarn-twisting chamber in the region of the blast air feed into the yarn channel. This is based on the model, that the open individual filaments of the yarn at the same time require an additional chamber to swing out to the side and thus generate improved knot stability. It is interesting that in the first case one achieves a higher number of knots. The disadvantage however is, that the stability of the knots and the uniformity of the knots sequence get noticeably worse even on slight reduction of the pressure of the blast air. In the second case, although the stability of the knots is adequate, the number of knots is not sufficient for several applications. The new invention have moved away from the so-called "vortex chamber". By vortex chamber one means a relatively large elongation of the yarn channel before and after the region of the air blow-in point. The objective was to give the yarn or individual filaments the possibility of swinging to and fro within the vortex chamber. The new invention, on the other hand, looks for an improvement on the air side. An air twist chamber or micro- twist chamber for the air is suggested. It is true that the stability of the knots could be increased with the vortex chamber. However, this was at the expense of the number of knots. Lesser number of knots per meter of yarn is generated. The individual knots are however longer. Astonishingly, in laboratory experiments with the new solution as per the invention, one could achieve a stability of the knots that was not achieved so far, with regular knots, almost without any loss with respect to the number of knots. The micro- twist of the air alone is possible, as the local airflow lies in the sonic and supersonic range and the phenomenon of supersonic flow is used, in that two strong, locally restricted steady air twist flows are forced. The inventor has further identified, that the methods used so far were based on an inadequate model of formation of the knots. The opposite twists in each flow-off direction are stable as long as there is no yarn in the yarn channel. The presence of yarn causes a to and fro swinging of the twists. Investigations by the applicant have shown, that the to and fro swinging of both the opposite twists within a short time is the key to the formation of knots. A combination of both big twists, as well as an indeterminable number of tiny twists causes to and fro pull and knotting of the individual filaments. The fact thereby is the complete instability of the counter-running twists, when yarn is transported through the yarn channel. As against that, one restricted oneself to double twist formation according to the model of the state-of-the-art technology. The contradiction involved was overlooked. It has now been determined by the inventor that the situation for treatment of fine yarn can be significantly improved, if instead of a continuous, uniform yarn feed channel or a yarn twist chamber, an air twist chamber is attached in the inlet region of the blast air in the yarn treatment channel, so that the air flow at the concerned point gets transferred into two strong, undisturbed twist flows. The air twist chamber represent a miniature blast air channel elongation and forms a transition between a completely stable twist flow in the region of air blow-in and the subsequent similarly completely unstable twist zone up to the exit out of the yarn channel. This gives a sharper twist force in yarn run direction, as well as against the yarn run direction. The airflows take place at sonic and supersonic velocities, so that the corresponding phenomenon can additionally be utilized. The invention permits a large number of advantageous extensions. The basis model is, that a short region of a twist flow is generated in the air twist chamber, which is subsequently followed in the yarn run direction as well as against the yarn run direction by an alternating twist zone. The following table gives an overview about the different yarn types with the corresponding filament fineness: Continuous filament yarns: sub-division of generally used yarn and filament fineness Deniers per filament (dpf) Yam type DTY-yarns Flat yarn BCF-yarns (False twist) (Bulk continuous filament) Yarn fineness soft medium hard soft medium hard soft medium hard Titre (denier) Filament fineness (for figures please see the original) Super micro Micro Soft Medium Hard Interlace stability: S=Soft M=Medium HD=Hard A series of extensive experiments with the solution as per the invention have shown, that for the blast air, compressed air of more than 0.5 bar is used, however lesser than 3 bar, and a knotted yarn with high stability of the yarn can be produced. Yarns lesser than 2 to 5 dpf, mainly lesser than 1 dpf, were treated. The yarn channel cross-section is preferably designed in semicircular or U-shape, whereby the yarn channel width (B) is greater than the yarn channel depth (T). The air twist chamber represents a cup-like air channel extension in the yarn channel. The air twist chamber is designed at least approx. symmetrical and projects on both sides lesser than 0.5 mm beyond the sidewalls of the yarn channel. A very important point of the new solution is. that the air twist chamber is designed in miniaturized form in such a way, that the yarn bundle cannot completely penetrate into the side extension of the air twist chamber. The air twist chamber projects only by a fraction of a millimetre beyond the air channel wall. Hence, for a 1.6 mm wide yarn channel the maximum width of the yarn chamber is suggested as 2.2 mm. It was initially totally surprising for all concerned, that with the help of such a tiny measure, correspondingly great effects could be achieved. The explanation lies in the specific design of the supersonic airflow. The new invention could be investigated with a series of experiments with DTY-yarns (draw twist yarns). The results were good for soft, medium and hard yarns. The most astonishing results were for soft yarns, particularly microfilament yarns. Initial experiments with flat yarns were positive, even though the results were significantly low with respect to DTY-yarns. At least on the basis of theoretical ideas, the new invention can also be applied for BCF-yarns, whereby in the case of BCF-yarns, on account of the much greater yarn channel widths of up to 8 mm, the air twist chamber should project by max. 22% and min. 5% of the yarn channel width. The new invention also allows a large number of design extensions of the yarn-twisting nozzle. Thus it is suggested that the yarn treatment cross-section be designed as semicircular or in U-shape and with a flat baffle cover. All experiments have clearly shown that the actual critical dimensions of the air twist chamber are the sideways projection and the longitudinal measurements. The air twist chamber is designed as a miniaturized cup with respect to the yarn treatment channel cross-section, similar in shape sideways, whereby the air twist chamber projects on both sides of the yarn treatment channel by lesser than 0.5 mm. A projection dimension of lesser than 0.5 mm could be confirmed with yarns up to 500 deniers, i.e. with yarn channel widths up to 3 mm. Comparative experiments: Impact of the twist chamber length Channel width B Twist chamber depth Twist chamber length Experiment result (mm) (%of B) (mm) state-of-the-art technology (for figures please see the original) good* according to invention state-of-the-art technology good, reference as per the invention good* bad* bad* bad* * = loss in knots, stability and uniformity = slight loss in knots, slight gain in stability * = optimum result with solution as per the invention For greater yarn channel widths above 3 mm, a projection dimension of lesser than 22% and greater than 5% of the yarn channel width is prescribed. The projection dimension should ideally lie between 10% and 20% of the yarn channel width. The air twist chamber further has an approx. circular-symmetrical contour and forms an extension of the centre axis of the blast air feed channel. For intensifying the sideways air twist formation, the width of the yarn channel cross-section should ideally be greater than the yarn channel depth in the direction of the blast air feed. The treatment channel could thereby be designed as wide channel with a width of preferably 0.6 to 3 mm, preferably with a ratio of yarn channel width (B) to yarn channel depth (T) of 1.2 to 2.5. According to experiments, the length of the air twist chamber should ideally be lesser than 1.3 times the yarn channel width. The length of the air twist chamber should preferably be approx. 0.7 to 1.6 times with respect to the yarn channel width, most specifically 0.8 to 1.2 times. which is significantly below L/B-ratio of approx. 1.75 as in the state-of-the-art technology. According to yet another design extension idea, the blast air feed channel is designed in round or oval shape or oval with triangular character or Y-shaped, whereby the side measurement of the blast air feed channel is maximum equal to or lesser than the corresponding yarn channel width. The yarn channel width (B) is designed greater than the air feed channel width d, preferably in a ratio of B/d of 1.1 to 3. According to yet another advantageous solution, it is suggested that the yarn channel be formed with the help of a flat shift-able buffer plate and a nozzle plate with the blast air feed. In this case, the yarn channel is preferably designed with a nozzle plate as well as a baffle plate that can be slid to it (as a so-called SlideJet), with an open position of the yarn channel for threading the yarn and a closed position of the yarn channel for producing knotted yarn. The nozzle plate is designed as a plate-like ceramic disc in such a way, that the ceramic disc along with a sliding part can be mounted in or dismantled from the twist nozzle, and/or that the ceramic disc can be mounted in or dismantled from the sliding part as change plate. The invention is now described in further details on the basis of a few design examples. The following are shown: Figs. 1 a-1 f The design of the yarn treatment channel as in the state-of-the-art technology, with the new findings of the counter-running twists on both flow-offsides; Figs.2a-2d The solution as per the invention with a twist air chamber; Figs.3a-3c Various cross-section shapes of the blast air feed channel; Fig.4a The result of a calculation model for the strong, steady twist flows in the region of the air twist chamber; Fig.4b The unsteady twists which are steady in the calculation model without the presence of the yarn; Fig.4c A schematic model for a steady twist flow in the region of the air twist chamber, as well as the unsteady twist of both flow-off directions of the treatment air; Figs.5a to 5e Various details of a nozzle plate with air twist chamber attached to it; Figs.6a to 6d A complete twisting nozzle of the type SlideJet in open and closed position, as well as with dismantled nozzle plate (figs. 6c or 6d); Figs.7a to 7f The most important subsequent steps for dismantling the slide plate or the nozzle plate; Figs.8a to 8d The mounting or dismantling of a nozzle plate in a sliding part of the twisting nozzle; Fig.9a Schematically an untreated flat yarn; Fig.9b A knotted yarn with soft knots; Fig.9c A knotted yarn with hard knots (dark lines); Fig.9d A knotted yarn as in the state-of-the-art technology very irregular formation of knots; Figs. 10a to 10c show, contrary to Fig. 9c to 9d, irregularity in the knots sequence, partly with varying distances, partly with missing knots; Fig. 11 shows a comparison of hard, almost un-releasable knots that have been generated with compressed air of 1.5 to 3 bar. On the right side of the Figure there are soft knots that are generated with compressed air of 0.5 to 1.5 bar and that mostly get released again in the course of yarn processing; Figs. 12a and 12b show a special shape of the blast air feed channel with a Y-shaped cross- section; Fig. 12c shows a further example for the extension of an air twist chamber 1 T as per the invention; Figs. 13a to 13d show a solution of the applicant as in the state-of-the-art technology with oversized yarn twisting channel; Fig. 14a shows a solution as per the invention; and Figs. 14b and 14c show solutions of the state-of-the-art technology as comparison to Fig. 14a; Figs. 15a to 15c show a comparison of the results with the solutions as per the state-of- the-art technology (figs. 15a and 15b), as well as a new solution (fig. 15c); Figs. 16a and 16b show important quality differences from comparative laboratory investigations with solutions as per the state-of-the-art technology, as well as with the new invention; Fig. 17 gives the experiment results comparing cases with and without air twist chamber with flat yarn "fully drawn" for different air pressures of the feed air. Figures la to 1f show the classical model for producing a knotted yarn 2" with the help of a twisting nozzle 1. Here, knots K are formed from an untwisted smooth yarn 2 in a yarn treatment channel 3 under the effect of blast air BL with individual filaments; these knots are formed according to the classical understanding from a double twist formation of the blast air, in yarn run direction 7 as well as against the yarn run direction within the yarn treatment channel 3. The blast air BL enters through a blast air channel 4 in the direction of the arrow 5 and generates the typical double twists 6, as one can see in figures 1 b and 1d. The knotted yarn 2' leaves the twisting nozzle 1 as indicated by the arrow 8. According to figures la and 1b the yarn treatment channel 3 has a round cross-section. The same holds good for the blast air channel 4. The solution as shown in figures 1c and 1d similarly conforms to the known state-of-the-art technology and represents an improved solution, to the extent that the yam channel 3 is formed by a semicircular shape in a nozzle plate 9 and a flat cover plate 10. By means of this specific shaping, one obtains significantly more pronounced double twists 6 as expressed in fig. Id. More extensive investigations in recent times have shown that the knowledge of formation of knots was rather incomplete. In fact, the formation of knots does not simply occur out of both these stable double twists 6. A basic pre-requisite for the formation of knots is the following fact: a) It is true that a double twist is generated with the blast air jet BL in the yarn treatment channel (figs. I band Id). b) The double twist is however completely disturbed as shown in figs. 1 c and If, if a filament yarn 2 enters into the yarn treatment channel 3. On entry of the yarn, the stable double twist is destroyed within milliseconds. A one-sided twist 6* gets formed in one half of the yarn treatment channel, whereas the twist 6 collapses. As a result, all filaments in the yarn treatment channel 3 swing to the right side. The gathering of all filaments on the right side however immediately destroys the double twist, so that a corresponding large twist 6* sets in on the left side (fig. 1b) almost without any time lag. This swinging movement in the presence of blast air and the filament yarn is a totally unsteady, permanent condition and ultimately the reason for formation of knots. Figures 2a to 2d show a solution as per the invention. Contrary to figures 1c to 1f, the yarn treatment channel 3 additionally has an air twist chamber 11 that represents an immediate extension of the blast air feed channel 4 into the yarn treatment channel 3. The yarn treatment channel 3 is extended in a cup at the point of the blast air feed channel 4, as one can see from the corresponding cup 12 in fig. 2d. Thus there is an additional twist flow in a section II, II of fig. 4, corresponding to both arrows 13, 13' in fig. 2a. The cup-shaped extension allows a locally steady twist flow without any negative influence of the unsteady twist movement in the subsequent part of the yarn treatment channel 3. The locally steady twist-flow immediately moves over into the unsteady twist flow as shown in both figures 2c and 2d. Fig. 2b shows a nozzle plate 9 designed as per the invention. Here, for the same features, the same reference signs have been used in figures 1 and 2. One can clearly identify the miniature design of the air twist chamber that is designed only sufficiently large, so that the filament bundle cannot move in it. Figures 3a to 3c show three different cross-sectional shapes for the blast air feed channel; fig. 3a with circular shape 4', fig. 3b with a semi-oval shape 4", as well as fig. 3c with an oval shape 4"'. Figures 4a and 4b respectively show the result of a CFD-flow calculation. In fig. 4a one can clearly identify the blast air feed BL from bottom to top. The upper level is denoted by E and depicts the target surface of the blast airflow BL on the baffle plate 10. The air twist chamber 11 is obtained from both the small cup-like recesses 12. One can clearly identify in fig. 4a both the twist flows 14, which in the range of lesser than 1 to 2 mm in longitudinal direction yield very stable flow patterns. In fig. 4a one can identify, on the basis of the same calculation model (without the presence of yarns), the steady twist flow 14 in the centre and both the double twists 6 at the top of the picture. Fig. 4c is a drawing that schematically depicts both the flow patterns. Figures 5a to 5e show the solution of Figures 2 to 4 as per the invention, attached in a concrete nozzle plate 9 for a SlightJet-nozzle. Figures 6a and 6b show an entire twisting nozzle I that is designed as SlightJet. Fig. 6b shows the open position or threading position and fig. 6a shows the closed operating position. A nozzle plate 9 is mounted in the twisting nozzle 1, whereby a sliding part 23 can slide to and fro on the lower shank of a yoke 25. A sliding lever 26 that converts the rotary movement into linear movement through corresponding mechanics effects the sliding movement. The rotary movement of the sliding lever 26 is thereby converted into pure sliding movement as indicated by the arrow 27. Very important for the twist is a baffle plate 10 that gets continuously pressed on to the upper plane surface of the nozzle plate 9 under spring pressure. The flat, plane surface with high surface quality allows the movement with simultaneous sealing function, for which a baffle plate 10 made of ceramic and a ceramic nozzle plate 9 are particularly suitable. The yarn channel 3 and an air feed channel are attached in the nozzle plate 9. For operating position, the air feed channel can be connected to a compressed air source 22. In the operating position, the yarn channel 3 is determined by the part visible in fig. 6a and the lower plane surface of the baffle plate 10. Fig. 6c shows a nozzle plate 9. Fig. 6d shows an entire sliding part 23 with inserted nozzle plate 9. Fig. 6d is also supposed to depict that the fastening of the nozzle plate 9 in the sliding part 23 leaves several solution possibilities open. The nozzle plate 9 can be cast-in directly into the sliding part 23 by an injection moulding process, so that the ceramic disc and the sliding part 23 form an inseparable component. It is also possible to affix/paste the ceramic disc into the sliding part. Fig. 7a shows the closed operating positions. The sliding lever 26 is situated in the countersunk position of the yarn channel 3 for through-run of the yarn for air treatment, for which compressed air can be fed through a connection or a compressed air hole/channel. By turning the sliding lever 26 upwards, the sliding part 23 gets pushed forward (fig. 7c) and at the same time the air feed is shut off, which is effected by shifting both the compressed air feed holes by the dimension G. By pressing a loose lever as shown by arrow K, the compressed spring force over the baffle plate 10 is lifted and the catch of a sliding axis is released into a catch groove, so that the sliding part 23 can be freely pushed forward (fig. 7b). The sliding part 23 can now be removed from the device (fig. 7f) and the ceramic disc can be removed in the direction of the sliding part 23. Reinstallation takes place in opposite directions to what is shown in figures 7a to 7f. Figures 8a to 8c depict an absolutely favourable connection. Fig. 8a shows the first step for installing the nozzle plate 9. The nozzle plate 9 is placed on the sliding part 23 transverse to the sliding direction, as shown by the arrow 41. A negative part and a positive part 42, 43 help in placing the nozzle plate 9 manually in a specialized manner, as shown in perspective depiction in fig. 8b. In fig. 8d the nozzle plate 9 is completely settled in sliding part 23, whereby already the rotation movement of the nozzle plate 9 can be identified by the arrow. The nozzle plate 9 has a cam on both sides and the sliding part 23 has a round sliding guide conforming to it. The nozzle plate 9 has circular segments on both sides with respect to a fulcrum; the circular segments fit into a corresponding circular guide of the sliding part 23 with little tolerance. After completion of the rotation movement as shown in fig. 8d, there is a stop point that catches from below by slight spring pressure and fixes the nozzle plate 9 in the operating position. Fig. 9a shows untwisted yarn 2. This can however be smooth as well as FZ-texturized. The straight lines indicate the individual filaments 45. Fig. 9b shows a softly twisted yarn. The typical feature thereby are the rather shorts knots K, whereby the knots are symbolized by thin straight lines. Fig. 9b shows hard, relatively long knots K between the twisted open positions. The hard knots are denoted by thicker lines. Fig. 9d shows a typical knotted yarn as per the state-of-the-art technology with very irregular knots. Figures 10a to 10c show a few examples with irregular knot formation. Fig. 11 is a comparison for hard and soft knots that can be produced with the help of the new invention. Fig. 11 shows a typical allied area of application of compressed air of 1.5 to 3 bar or 0.5 to 1.5 bar. Depending on the market and mainly the nature of further processing, hard knots or soft knots are required. Figures 12a and 12d show the possibility of application of a Y-shaped blast air channel cross-section with corresponding main air channel H and side air channel N. Fig. 12c shows a further example for the design of an air twist chamber 11' as per the invention. Figures 13a to 13c show a solution as per the state-of-the-art technology, as produced by the applicant for already over 20 years. Here one finds a typically long yarn-twisting chamber with relatively large width and length. This solution was based on the model, that the yarn could swing out in the yarn-twisting chamber to a very large extent. Fig. 14a shows a solution as per the invention and as comparison (figs. 14b, 14c) two solutions as per the state-of-the-art technology. All investigations so far have revealed that there is a critical dimension for the projection of the air twist chamber. This is approx. 0.5 mm. In all chamber designs, where the chamber projects by more than 0.5 mm sideways, one can determine a clear reduction in quality. Experiments so far have shown that the sideways projection of the chamber over the yarn treatment channel 3 should be assessed as critical. It was determined that it is advantageous if the length of the chamber in the yarn channel in the longitudinal direction is lesser than 1.3 times the yarn channel width (B). Figures 15a. 15b and 15c show a comparison of the knots formation: fig. 15a according to a solution as shown in figures 13a to 13c; fig. 15b according to a solution without twisting chamber as shown in figures i and 1a; and fig. 15c a solution as per the invention. In all three solutions, yarns of 80 f 72, 80 f 108, 72 f 72 and 80 f 34 are used. Depending on the method of operation or the pressure of the blast air, one obtains soft or hard knots. Both the figures 16a and 16b show results with comparative experiments - fig. J 6a with coarse yarn and fig. 16b with fine yarn. The left-side figure always shows the number of knots per meter, the central figure shows the dispersion of the knots and the right-side figure shows the stability or the knots-loss under tensile stress. Even nozzles with no chamber or with round chambers were used (with cup-widths K. of 2.2; 2.4; 2.6; 2.8 mm). The chamber was designed in cup shape. One can clearly see that the cup-width K of 2.2 mm as per the invention with a real air twist chamber as per the invention, produces the best result. In all experiments the yarn channel width was 1.6 mm, the yarn channel depth 1.0 mm and the air blow-in hole 1.1 mm. The advantages as per the invention are also visible, if additionally elasthane yarns are also introduced into the nozzle and combined with the filament yarns already mentioned before. Patent claims I. Method for producing knotted yarn or twisted yarn from DTY-yarn and/or flat yarns with a high degree of regularity of knots with the help of air jets, with a yarn treatment channel and blast air that is blown-in transverse to the yarn treatment channel, whereby the blast air forms a double twist in the yarn run direction as well as against the yarn run direction, producing knots, having the distinctive feature that the blast air in the inlet region into the yarn treatment channel gets transferred in an air twist chamber into two strong steady twist flows almost undisturbed by the filament bundle. 2. Method as per claim 1, having the distinctive feature that in the air twist chamber a short region with a steady twist flow is generated, on to which subsequently follows an alternating twist zone, both in the yarn run direction as well as against the yarn run direction. 3. Method as per claim 1 or 2, having the distinctive feature that for the blast air a pressure of 0.5 to 1.5 bar is used, for producing soft knots that can get released again during further processing. 4. Method as per claim 1 or 2, having the distinctive feature that for the blast air, compressed air of above 1.5 bar is used, for producing hard knots that do not get released during further processing. 5. Method as per one of the claims 1 to 4, having the distinctive feature that yarns with lesser than 10 to 15 dpf, preferably finer than 2 dpf, are treated. 6. Method as per one of the claims 1 to 5, having the distinctive feature that the yarn channel cross-section is designed in semicircular shape or U-shape, whereby the yarn channel width (B) is greater than the yarn channel depth (T). 7. Method as per one of the claims 1 to 6, having the distinctive feature that the air twist chamber represents a cup-shaped air channel extension in the yarn channel and the flow flows through the yarn channel in a shape conforming to the cross-section. 8. Method as per one of the claims 1 to 6, having the distinctive feature that the air twist chamber is designed at least approx. symmetrical to the yarn channel centre axis and, for producing DTY-yarn, projects over the side yarn channel walls by 9. Method as per one of the claims 1 to 8, having the distinctive feature that the air twist chamber projects beyond the blast air feed channel in yarn channel longitudinal direction by lesser than 0.5 mm, however max. 22% and min. 5% of the yarn channel width (B). 10. Method as per one of the claims 1 to 8, having the distinctive feature that the air twist chamber is designed in a miniaturized form in such a way, that the filament bundle cannot penetrate into the sideways extension of the air twist chamber. 11. Twisting nozzle for producing knotted yarn with high regularity of the knots, with a continuous yarn treatment channel as well as a blast air feed channel, whereby the blast air feed channel is aligned to the longitudinal centre axis of the air treatment channel, having the distinctive feature that in the mouth region of the blast air feed channel in the yarn treatment channel a blast air channel extension is formed for creating an air twist chamber for two opposite steady twist flows, whereby the blast air channel extension projects by lesser than 22%, however more than 5%, of the yarn channel width. 12. Twisting nozzle as per claim 11, having the distinctive feature that the yarn treatment cross-section is designed as semicircular or U-shaped with a flat baffle cover. 13. Twisting nozzle as per claim 11 or 12, having the distinctive feature that the air twist chamber is designed as a miniaturized cup and is similar in shape sideways with respect to the yarn treatment channel cross-section. 14. Twisting nozzle as per one of the claims 11 to 13, having the distinctive feature that the air twist chamber projects beyond the yarn treatment channel on both sides by lesser than 0.5 mm. 15. Twisting nozzle as per one of the claims 11 to 14, having the distinctive feature that the air twist chamber has a length in yarn channel longitudinal direction that is lesser than 1.3 times the yarn channel width (B). 16. Twisting nozzle as per one of the claims I I to 15, having the distinctive feature that the air twist chamber has a at least approx. circular-symmetrical outer contour and preferably forms an extension of the centre axis of the blast air channel. 17. Twisting nozzle as per one of the claims 11 to 16, having the distinctive feature that for intensifying the sideways air twist formation, the width of the yarn channel cross-section is greater than the yarn channel depth in the direction of the blast air feed. 18. Twisting nozzle as per claim 17, having the distinctive feature that the treatment channel is designed as a wide channel with a width of preferably 0.6 to 3 mm, ideally with a ratio of yarn channel width (B) to yarn channel depth (T) of 1.1 to 2.5. 19. Twisting nozzle as per one of the claims 11 to 18, having the distinctive feature that the blast air feed channel is designed in a round or oval shape or oval with triangular character or Y-shaped, whereby the side measurement of the blast air feed channel is maximum equal to or lesser than the corresponding yarn channel width. 20. Twisting nozzle as per claim 17 or 19, having the distinctive feature that the yarn channel width (B) is greater than the air feed width d, preferably in a ratio B/d of 1.2 to 3. 21. Twisting nozzle as per one of the claims 11 to 20, having the distinctive feature that the yarn channel is formed by a flat slide-able buffer plate and a nozzle plate with the blast air feed. 22. Twisting nozzle as per one of the claims 11 to 21. having the distinctive feature that the yarn channel is designed by means of a nozzle plate and a buffer plate that can be slid to it, as so-called SlightJet, with an open position of the yarn channel for threading the yarn and a closed position of the yarn channel for producing a knotted yarn. 23. Twisting nozzle as per one of the claims 11 to 22, having the distinctive feature that the nozzle plate is designed as a plate-like ceramic disc and the ceramic disc along with the sliding part can be mounted in or dismantled from the twisting nozzle, and/or that the ceramic disc can be mounted in or dismantled from the sliding part as change plate. 24. Application of the twisting nozzle as per one of the claims 11 to 23 for producing knotted yarn from DCF-yarns. The new invention pertains to a twisting nozzle and a method for producing fine, knotted yarn with a high regularity of the knots, with the help of air nozzles with a yarn treatment channel. The blast air is blown in, transverse to the air treatment channel. The blast air thereby forms a double twist in yarn run direction as well as against the yarn run direction, for generating the knots. For this, it is suggested that the blast air in the inlet region into the yam treatment channel gets converted in a short air twist chamber in yarn channel longitudinal direction into two strong, steady twist flows undisturbed by filament bundles. In spite of the tiny nature of the air twist chamber, which projects max. 0.5 mm or 5% to 22% of the yarn channel width (B) beyond the yarn channel longitudinal wall, the regularity of the knots can be highly improved. It is further possible, depending on the pressure of the blast air, to generate hard or soft knots that get released again.

Full Text

Method and Twisting Nozzle for Producing Knotted Yarn
The invention pertains to a method for producing knotted yarn or draw twist yarn and/or
flat yarns with a high degree of regularity of the knots by means of air jets, with a yarn
treatment channel as well as blast air that is blown in transverse to the yarn treatment
channel, whereby the blast air forms a double twist for producing the knots in the yarn
transporting direction as well as against the yarn transporting direction. The invention
further pertains to a twisting nozzle for production of knotted yarn with a high degree of
regularity of the knots, with a continuous yarn treatment channel, as well as a blast air
feed channel, whereby the blast air feed channel is aligned to the longitudinal central axis
of the yarn treatment channel.
In the recent past, increasingly finer filaments were produced. These are referred to as
microfilaments, if the denier per filament (dpf) lies between 0.5 and approx. 1.2. The
yarns thus produced are called microfilament yarns. One refers to them as super
microfilament yarns if the dps is below, these include also super microfilaments, unless otherwise mentioned. Already
yarns with a dps above 1.2 require careful processing, so that neither the individual
filaments nor the entire yarn break. This applies to a greater extent in the case of
microfilament yarns. In case of microfilament yarns, the bundle of all filaments has an
important significance. Care should be taken that individual filaments do not stray away
and hence pose the danger of breaking. DTY-yarns mean drawn-twist-yarn.
There is a relatively large use of twisted yarns with so-called air twist in the market. The
market indicates two tendencies. In many cases of application, well-structured, strong
and stable knots in all degrees of filament fineness are in demand. The air nozzle has to
be designed for that with respect to all parameters. The situation is different in case of
fine microfilament yarns. With these yarns, fine fabrics are produced that should have a
soft and silk-like feel. Here one can see that the formation of very stable and almost
unreleasable knots could be disadvantageous, in that the knots leave the mark in an
undesirable manner, as a kind of screen, especially on a very fine, single coloured fabrics.
Even though knots are desirable within the yarn processing, they should completely
disappear later while processing the fine yarns into fabrics or other substances. The so-
called knotted yarn is produced by twisting in the twisting nozzle. The knots ensure the
local binding of all filaments and short knot sequences over the entire yarn run. The
objective of twisting is to achieve a high number of knots per meter with uniform
distance between the knots. A yarn treatment channel, with a blast air feed transverse to
the yarn channel, provides the device-specific conditions. The blast air flows away on
both sides of the yarn channel and on account of the almost centric blowing in the yarn
run direction and against the yarn run direction, forms so-called double twists. By taking
the yarn through the corresponding twist zone one obtains the kind of alternative air
movement that is ultimately co-responsible for a repetitive formation of knots with short
interruptions between the knots. The skill lies in finding an optimum solution for the
respective application case between the three yarn quality criteria,
Knot stability;
Number of knots per meter;
Regularity of knot formation,
with specific designing of all dimensions of the yarn channel of a twisting nozzle, as well
as the type of air feeding, air pressure, overfeed and the yarn run velocity. In coarser
filaments having dpf 1.2 - 4, a number of up to 110 knots is desirable and in
microfilament yarns up to 200 per meter of yarn. The air pressure for microfilaments is
approx. 0.5 to 1.5 bar. The overfeed is 3% - 6%. In the state-of-the-art technology, for
fine filaments, 140 points or knots per meter of yarn length are generated. The highest
possible uniformity/regularity of the knots sequence is thereby desirable. It should be
prevented, that knot-free yarn stretches occur, in which one or more knots are
successively missing. The extent of stability tells us, under which tensile forces the knots
again get released. In the simplest method for testing this, the yarn is held between two
hands and stretched slowly or in a jerky manner.
The document DE 197 00 817 shows a special form of twisting nozzle for carpet yarn,
i.e. for very coarse BCF-yarn. It was based on a method for continuous production of
weave-texturized filament yarn in a continuous yarn channel or twisting channel of a
twisting nozzle. The filament yarn is twisted by a blast airflow directed in a transverse
direction into the nozzle that is flowing forwards and backwards out of the yarn channel
and the discharge air of the reversed twist is released in counter-direction to the blast air
feed from the yarn feeding region. As solution it is suggested that two twists with
different strengths get generated in the twisting channel, whereby the forward twist is
designed to be more strongly effective than the reverse twist.
The document DE 37 11 759 is based on finer to average yarns and tries to improve the
process-ability of the yarn in subsequent processing stages, e.g. in looms, drafting
machines and tufting machines. The inventor started off with a twisting device for
twisting multi-filament yarns, which have at least one yarn channel, whereby yarn guides
are arranged at distances from the inlet and outlet of the yarn channel, and the filaments
of one multi-filament yarn can be twisted in the yarn channel by means of compressed air
which can be blown in through a blast nozzle. While running into and running out of the
yarn channel, the yarn experiences a change in direction of less than 90°, and the blowing
angle of the blast nozzle is lesser than 90°. As a new solution, it is suggested that the
yarn guides be arranged in such a way, that the yarn is placed through them in such a way
on the yarn channel, with the compressed air feed switched off, that it stretches in the
yarn channel parallel to its longitudinal direction, and thereby acts at the exit of the at
least one blast nozzle. The distance of the yarn guides from their adjacent yarn channel
openings is maximum 30 mm. The length of the yarn channel for un-crimped multi-
filament yarns is max. 40 mm and for crimped multifilament yam max. 30 mm. The
document DE 37 11 759 is useful at least to the extent, that the knowledge of the positive
effect of a short yarn channel is useful for producing knotted yarn in a wider specialized
world. Concretely, a yarn channel length for texturized or crimped yarns is suggested as
10-28 mm. Especially, the range of 10 mm of yarn channel length is considered as
short.
Latest experience shows that the actually widespread application of air nozzles for
producing knotted yarn is not satisfactory for very fine yarns, particularly in
microfilaments. With respect to fine yarns, particularly in microfilament yarns, in any
case there is a requirement of maximum regularity of the knot sequence; however, in
certain cases of application, only weak, temporarily constant and reversible, i.e. knots
that get released again during yarn processing, are required. The knots should not be
noticeable in the finished fabrics. It has been attempted several times to operate nozzles
of the state-of-the-art technology with lower pressure of the feed air. It is known that
with lower air pressure one gets weaker knots, however with the disadvantage of an often
not acceptable non-uniformity in the strength or stability of the knots, as well as the
distances between the knots.
Recently there is very strong tendency in the market to use so-called microfilament yarns.
The question of uniformity of the knots, as well as at least an adequate stability of the
knots for further processing thereby acquires central importance in many cases of
application. In most cases it is required that the number of knots does not fall
significantly short of the figure of 140 knots/m that can be achieved at the moment; it is
furthermore required that the required pressure for blast air should be reduced, keeping in
view the energy consumption. It is now the task of this invention to find a method as
well as a twisting nozzle, with the help of which even at high yarn run velocity, the above
mentioned quality criteria can be achieved in the production of fine yarns and particularly
microfilament yarns, with the following four objectives:
- Pressure reduction of the blast air;
- Number of knots per meter > 140/m fordpf - Adjustable knot stability;
- High uniformity of the knots sequence.
The method as per invention has the feature, that the blast air in the entry region into the
yarn treatment channel is transferred in an air twisting chamber into two strong, steads
air twist flows almost undisturbed by filament bundles.
The twisting nozzle as per the invention has a distinctive feature, that in the mouth region
of the blast air feed channel in the yarn treatment channel, a blast air channel elongation
is formed for creating an air twisting chamber for two opposite steady air twist flows,
whereby the blast air channel elongation protrudes by lesser than 22% of the yarn channel
width, however more than 5%.
With reference to the new invention, two twisting nozzles are known in the state-of-the-
art technology:
- Firstly, these are twisting nozzles with continuous yarn channels, as described in the
introductory part of DE 37 11 759. The typical characteristic thereby is a uniform
continuous yarn channel.
- Secondly, these are twisting nozzles with a yarn-twisting chamber in the region of the
blast air feed into the yarn channel. This is based on the model, that the open individual
filaments of the yarn at the same time require an additional chamber to swing out to the
side and thus generate improved knot stability.
It is interesting that in the first case one achieves a higher number of knots. The
disadvantage however is, that the stability of the knots and the uniformity of the knots
sequence get noticeably worse even on slight reduction of the pressure of the blast air. In
the second case, although the stability of the knots is adequate, the number of knots is not
sufficient for several applications.
The new invention have moved away from the so-called "vortex chamber". By vortex
chamber one means a relatively large elongation of the yarn channel before and after the
region of the air blow-in point. The objective was to give the yarn or individual filaments
the possibility of swinging to and fro within the vortex chamber. The new invention, on
the other hand, looks for an improvement on the air side. An air twist chamber or micro-
twist chamber for the air is suggested. It is true that the stability of the knots could be
increased with the vortex chamber. However, this was at the expense of the number of
knots. Lesser number of knots per meter of yarn is generated. The individual knots are
however longer. Astonishingly, in laboratory experiments with the new solution as per
the invention, one could achieve a stability of the knots that was not achieved so far, with
regular knots, almost without any loss with respect to the number of knots. The micro-
twist of the air alone is possible, as the local airflow lies in the sonic and supersonic range
and the phenomenon of supersonic flow is used, in that two strong, locally restricted
steady air twist flows are forced.
The inventor has further identified, that the methods used so far were based on an
inadequate model of formation of the knots. The opposite twists in each flow-off
direction are stable as long as there is no yarn in the yarn channel. The presence of yarn
causes a to and fro swinging of the twists. Investigations by the applicant have shown,
that the to and fro swinging of both the opposite twists within a short time is the key to
the formation of knots. A combination of both big twists, as well as an indeterminable
number of tiny twists causes to and fro pull and knotting of the individual filaments. The
fact thereby is the complete instability of the counter-running twists, when yarn is
transported through the yarn channel. As against that, one restricted oneself to double
twist formation according to the model of the state-of-the-art technology. The
contradiction involved was overlooked. It has now been determined by the inventor that
the situation for treatment of fine yarn can be significantly improved, if instead of a
continuous, uniform yarn feed channel or a yarn twist chamber, an air twist chamber is
attached in the inlet region of the blast air in the yarn treatment channel, so that the air
flow at the concerned point gets transferred into two strong, undisturbed twist flows. The
air twist chamber represent a miniature blast air channel elongation and forms a transition
between a completely stable twist flow in the region of air blow-in and the subsequent
similarly completely unstable twist zone up to the exit out of the yarn channel. This
gives a sharper twist force in yarn run direction, as well as against the yarn run direction.
The airflows take place at sonic and supersonic velocities, so that the corresponding
phenomenon can additionally be utilized.
The invention permits a large number of advantageous extensions. The basis model is,
that a short region of a twist flow is generated in the air twist chamber, which is
subsequently followed in the yarn run direction as well as against the yarn run direction
by an alternating twist zone. The following table gives an overview about the different
yarn types with the corresponding filament fineness:
Continuous filament yarns: sub-division of generally used yarn and filament fineness
Deniers per filament (dpf)
Yam type DTY-yarns Flat yarn BCF-yarns
(False twist) (Bulk continuous filament)
Yarn fineness soft medium hard soft medium hard soft medium hard
Titre (denier)
Filament fineness (for figures please see the original)
Super micro
Micro
Soft
Medium
Hard
Interlace stability: S=Soft M=Medium HD=Hard
A series of extensive experiments with the solution as per the invention have shown, that
for the blast air, compressed air of more than 0.5 bar is used, however lesser than 3 bar,
and a knotted yarn with high stability of the yarn can be produced. Yarns lesser than 2 to
5 dpf, mainly lesser than 1 dpf, were treated. The yarn channel cross-section is
preferably designed in semicircular or U-shape, whereby the yarn channel width (B) is
greater than the yarn channel depth (T). The air twist chamber represents a cup-like air
channel extension in the yarn channel. The air twist chamber is designed at least approx.
symmetrical and projects on both sides lesser than 0.5 mm beyond the sidewalls of the
yarn channel. A very important point of the new solution is. that the air twist chamber is
designed in miniaturized form in such a way, that the yarn bundle cannot completely
penetrate into the side extension of the air twist chamber. The air twist chamber projects
only by a fraction of a millimetre beyond the air channel wall. Hence, for a 1.6 mm wide
yarn channel the maximum width of the yarn chamber is suggested as 2.2 mm. It was
initially totally surprising for all concerned, that with the help of such a tiny measure,
correspondingly great effects could be achieved. The explanation lies in the specific
design of the supersonic airflow.
The new invention could be investigated with a series of experiments with DTY-yarns
(draw twist yarns). The results were good for soft, medium and hard yarns. The most
astonishing results were for soft yarns, particularly microfilament yarns. Initial
experiments with flat yarns were positive, even though the results were significantly low
with respect to DTY-yarns. At least on the basis of theoretical ideas, the new invention
can also be applied for BCF-yarns, whereby in the case of BCF-yarns, on account of the
much greater yarn channel widths of up to 8 mm, the air twist chamber should project by
max. 22% and min. 5% of the yarn channel width.
The new invention also allows a large number of design extensions of the yarn-twisting
nozzle. Thus it is suggested that the yarn treatment cross-section be designed as
semicircular or in U-shape and with a flat baffle cover.
All experiments have clearly shown that the actual critical dimensions of the air twist
chamber are the sideways projection and the longitudinal measurements. The air twist
chamber is designed as a miniaturized cup with respect to the yarn treatment channel
cross-section, similar in shape sideways, whereby the air twist chamber projects on both
sides of the yarn treatment channel by lesser than 0.5 mm. A projection dimension of
lesser than 0.5 mm could be confirmed with yarns up to 500 deniers, i.e. with yarn
channel widths up to 3 mm.
Comparative experiments: Impact of the twist chamber length
Channel width B Twist chamber depth Twist chamber length Experiment result
(mm) (%of B) (mm) state-of-the-art
technology
(for figures please see the original) good*** according
to invention
state-of-the-art
technology
good***, reference
as per the invention
good**
bad*
bad*
bad*
* = loss in knots, stability and uniformity
** = slight loss in knots, slight gain in stability
*** = optimum result with solution as per the invention
For greater yarn channel widths above 3 mm, a projection dimension of lesser than 22%
and greater than 5% of the yarn channel width is prescribed. The projection dimension
should ideally lie between 10% and 20% of the yarn channel width. The air twist
chamber further has an approx. circular-symmetrical contour and forms an extension of
the centre axis of the blast air feed channel. For intensifying the sideways air twist
formation, the width of the yarn channel cross-section should ideally be greater than the
yarn channel depth in the direction of the blast air feed. The treatment channel could
thereby be designed as wide channel with a width of preferably 0.6 to 3 mm, preferably
with a ratio of yarn channel width (B) to yarn channel depth (T) of 1.2 to 2.5. According
to experiments, the length of the air twist chamber should ideally be lesser than 1.3 times
the yarn channel width. The length of the air twist chamber should preferably be approx.
0.7 to 1.6 times with respect to the yarn channel width, most specifically 0.8 to 1.2 times.
which is significantly below L/B-ratio of approx. 1.75 as in the state-of-the-art
technology.
According to yet another design extension idea, the blast air feed channel is designed in
round or oval shape or oval with triangular character or Y-shaped, whereby the side
measurement of the blast air feed channel is maximum equal to or lesser than the
corresponding yarn channel width. The yarn channel width (B) is designed greater than
the air feed channel width d, preferably in a ratio of B/d of 1.1 to 3.
According to yet another advantageous solution, it is suggested that the yarn channel be
formed with the help of a flat shift-able buffer plate and a nozzle plate with the blast air
feed. In this case, the yarn channel is preferably designed with a nozzle plate as well as a
baffle plate that can be slid to it (as a so-called SlideJet), with an open position of the
yarn channel for threading the yarn and a closed position of the yarn channel for
producing knotted yarn. The nozzle plate is designed as a plate-like ceramic disc in such
a way, that the ceramic disc along with a sliding part can be mounted in or dismantled
from the twist nozzle, and/or that the ceramic disc can be mounted in or dismantled from
the sliding part as change plate.
The invention is now described in further details on the basis of a few design examples.
The following are shown:
Figs. 1 a-1 f The design of the yarn treatment channel as in the state-of-the-art
technology, with the new findings of the counter-running twists on both
flow-offsides;
Figs.2a-2d The solution as per the invention with a twist air chamber;
Figs.3a-3c Various cross-section shapes of the blast air feed channel;
Fig.4a The result of a calculation model for the strong, steady twist flows in the
region of the air twist chamber;
Fig.4b The unsteady twists which are steady in the calculation model without the
presence of the yarn;
Fig.4c A schematic model for a steady twist flow in the region of the air twist
chamber, as well as the unsteady twist of both flow-off directions of the
treatment air;
Figs.5a to 5e Various details of a nozzle plate with air twist chamber attached to it;
Figs.6a to 6d A complete twisting nozzle of the type SlideJet in open and closed
position, as well as with dismantled nozzle plate (figs. 6c or 6d);
Figs.7a to 7f The most important subsequent steps for dismantling the slide plate or the
nozzle plate;
Figs.8a to 8d The mounting or dismantling of a nozzle plate in a sliding part of the
twisting nozzle;
Fig.9a Schematically an untreated flat yarn;
Fig.9b A knotted yarn with soft knots;
Fig.9c A knotted yarn with hard knots (dark lines);
Fig.9d A knotted yarn as in the state-of-the-art technology very irregular
formation of knots;
Figs. 10a to 10c show, contrary to Fig. 9c to 9d, irregularity in the knots sequence, partly
with varying distances, partly with missing knots;
Fig. 11 shows a comparison of hard, almost un-releasable knots that have been
generated with compressed air of 1.5 to 3 bar. On the right side of the
Figure there are soft knots that are generated with compressed air of 0.5 to
1.5 bar and that mostly get released again in the course of yarn processing;
Figs. 12a and 12b show a special shape of the blast air feed channel with a Y-shaped
cross- section;
Fig. 12c shows a further example for the extension of an air twist chamber 1 T as
per the invention;
Figs. 13a to 13d show a solution of the applicant as in the state-of-the-art technology with
oversized yarn twisting channel;
Fig. 14a shows a solution as per the invention; and
Figs. 14b and 14c show solutions of the state-of-the-art technology as comparison to Fig.
14a;
Figs. 15a to 15c show a comparison of the results with the solutions as per the state-of-
the-art technology (figs. 15a and 15b), as well as a new solution (fig. 15c);
Figs. 16a and 16b show important quality differences from comparative laboratory
investigations with solutions as per the state-of-the-art technology, as well
as with the new invention;
Fig. 17 gives the experiment results comparing cases with and without air twist
chamber with flat yarn "fully drawn" for different air pressures of the feed
air.
Figures la to 1f show the classical model for producing a knotted yarn 2" with the help of
a twisting nozzle 1. Here, knots K are formed from an untwisted smooth yarn 2 in a yarn
treatment channel 3 under the effect of blast air BL with individual filaments; these knots
are formed according to the classical understanding from a double twist formation of the
blast air, in yarn run direction 7 as well as against the yarn run direction within the yarn
treatment channel 3. The blast air BL enters through a blast air channel 4 in the direction
of the arrow 5 and generates the typical double twists 6, as one can see in figures 1 b and
1d. The knotted yarn 2' leaves the twisting nozzle 1 as indicated by the arrow 8.
According to figures la and 1b the yarn treatment channel 3 has a round cross-section.
The same holds good for the blast air channel 4. The solution as shown in figures 1c and
1d similarly conforms to the known state-of-the-art technology and represents an
improved solution, to the extent that the yam channel 3 is formed by a semicircular shape
in a nozzle plate 9 and a flat cover plate 10. By means of this specific shaping, one
obtains significantly more pronounced double twists 6 as expressed in fig. Id.
More extensive investigations in recent times have shown that the knowledge of
formation of knots was rather incomplete. In fact, the formation of knots does not simply
occur out of both these stable double twists 6. A basic pre-requisite for the formation of
knots is the following fact:
a) It is true that a double twist is generated with the blast air jet BL in the yarn
treatment channel (figs. I band Id).
b) The double twist is however completely disturbed as shown in figs. 1 c and If, if a
filament yarn 2 enters into the yarn treatment channel 3. On entry of the yarn, the
stable double twist is destroyed within milliseconds. A one-sided twist 6* gets
formed in one half of the yarn treatment channel, whereas the twist 6** collapses.
As a result, all filaments in the yarn treatment channel 3 swing to the right side.
The gathering of all filaments on the right side however immediately destroys the
double twist, so that a corresponding large twist 6*** sets in on the left side
(fig. 1b) almost without any time lag. This swinging movement in the presence of
blast air and the filament yarn is a totally unsteady, permanent condition and
ultimately the reason for formation of knots.
Figures 2a to 2d show a solution as per the invention. Contrary to figures 1c to 1f, the
yarn treatment channel 3 additionally has an air twist chamber 11 that represents an
immediate extension of the blast air feed channel 4 into the yarn treatment channel 3.
The yarn treatment channel 3 is extended in a cup at the point of the blast air feed channel
4, as one can see from the corresponding cup 12 in fig. 2d. Thus there is an additional
twist flow in a section II, II of fig. 4, corresponding to both arrows 13, 13' in fig. 2a. The
cup-shaped extension allows a locally steady twist flow without any negative influence of
the unsteady twist movement in the subsequent part of the yarn treatment channel 3. The
locally steady twist-flow immediately moves over into the unsteady twist flow as shown
in both figures 2c and 2d. Fig. 2b shows a nozzle plate 9 designed as per the invention.
Here, for the same features, the same reference signs have been used in figures 1 and 2.
One can clearly identify the miniature design of the air twist chamber that is designed
only sufficiently large, so that the filament bundle cannot move in it.
Figures 3a to 3c show three different cross-sectional shapes for the blast air feed channel;
fig. 3a with circular shape 4', fig. 3b with a semi-oval shape 4", as well as fig. 3c with an
oval shape 4"'.
Figures 4a and 4b respectively show the result of a CFD-flow calculation. In fig. 4a one
can clearly identify the blast air feed BL from bottom to top. The upper level is denoted
by E and depicts the target surface of the blast airflow BL on the baffle plate 10. The air
twist chamber 11 is obtained from both the small cup-like recesses 12. One can clearly
identify in fig. 4a both the twist flows 14, which in the range of lesser than 1 to 2 mm in
longitudinal direction yield very stable flow patterns. In fig. 4a one can identify, on the
basis of the same calculation model (without the presence of yarns), the steady twist flow
14 in the centre and both the double twists 6 at the top of the picture. Fig. 4c is a drawing
that schematically depicts both the flow patterns.
Figures 5a to 5e show the solution of Figures 2 to 4 as per the invention, attached in a
concrete nozzle plate 9 for a SlightJet-nozzle.
Figures 6a and 6b show an entire twisting nozzle I that is designed as SlightJet. Fig. 6b
shows the open position or threading position and fig. 6a shows the closed operating
position. A nozzle plate 9 is mounted in the twisting nozzle 1, whereby a sliding part 23
can slide to and fro on the lower shank of a yoke 25. A sliding lever 26 that converts the
rotary movement into linear movement through corresponding mechanics effects the
sliding movement. The rotary movement of the sliding lever 26 is thereby converted into
pure sliding movement as indicated by the arrow 27. Very important for the twist is a
baffle plate 10 that gets continuously pressed on to the upper plane surface of the nozzle
plate 9 under spring pressure. The flat, plane surface with high surface quality allows the
movement with simultaneous sealing function, for which a baffle plate 10 made of
ceramic and a ceramic nozzle plate 9 are particularly suitable. The yarn channel 3 and an
air feed channel are attached in the nozzle plate 9. For operating position, the air feed
channel can be connected to a compressed air source 22. In the operating position, the
yarn channel 3 is determined by the part visible in fig. 6a and the lower plane surface of
the baffle plate 10. Fig. 6c shows a nozzle plate 9. Fig. 6d shows an entire sliding part
23 with inserted nozzle plate 9. Fig. 6d is also supposed to depict that the fastening of the
nozzle plate 9 in the sliding part 23 leaves several solution possibilities open. The nozzle
plate 9 can be cast-in directly into the sliding part 23 by an injection moulding process, so
that the ceramic disc and the sliding part 23 form an inseparable component. It is also
possible to affix/paste the ceramic disc into the sliding part.
Fig. 7a shows the closed operating positions. The sliding lever 26 is situated in the
countersunk position of the yarn channel 3 for through-run of the yarn for air treatment,
for which compressed air can be fed through a connection or a compressed air
hole/channel. By turning the sliding lever 26 upwards, the sliding part 23 gets pushed
forward (fig. 7c) and at the same time the air feed is shut off, which is effected by shifting
both the compressed air feed holes by the dimension G. By pressing a loose lever as
shown by arrow K, the compressed spring force over the baffle plate 10 is lifted and the
catch of a sliding axis is released into a catch groove, so that the sliding part 23 can be
freely pushed forward (fig. 7b). The sliding part 23 can now be removed from the device
(fig. 7f) and the ceramic disc can be removed in the direction of the sliding part 23.
Reinstallation takes place in opposite directions to what is shown in figures 7a to 7f.
Figures 8a to 8c depict an absolutely favourable connection. Fig. 8a shows the first step
for installing the nozzle plate 9. The nozzle plate 9 is placed on the sliding part 23
transverse to the sliding direction, as shown by the arrow 41. A negative part and a
positive part 42, 43 help in placing the nozzle plate 9 manually in a specialized manner,
as shown in perspective depiction in fig. 8b. In fig. 8d the nozzle plate 9 is completely
settled in sliding part 23, whereby already the rotation movement of the nozzle plate 9
can be identified by the arrow. The nozzle plate 9 has a cam on both sides and the sliding
part 23 has a round sliding guide conforming to it. The nozzle plate 9 has circular
segments on both sides with respect to a fulcrum; the circular segments fit into a
corresponding circular guide of the sliding part 23 with little tolerance. After completion
of the rotation movement as shown in fig. 8d, there is a stop point that catches from
below by slight spring pressure and fixes the nozzle plate 9 in the operating position.
Fig. 9a shows untwisted yarn 2. This can however be smooth as well as FZ-texturized.
The straight lines indicate the individual filaments 45. Fig. 9b shows a softly twisted
yarn. The typical feature thereby are the rather shorts knots K, whereby the knots are
symbolized by thin straight lines. Fig. 9b shows hard, relatively long knots K between
the twisted open positions. The hard knots are denoted by thicker lines. Fig. 9d shows a
typical knotted yarn as per the state-of-the-art technology with very irregular knots.
Figures 10a to 10c show a few examples with irregular knot formation.
Fig. 11 is a comparison for hard and soft knots that can be produced with the help of the
new invention. Fig. 11 shows a typical allied area of application of compressed air of 1.5
to 3 bar or 0.5 to 1.5 bar. Depending on the market and mainly the nature of further
processing, hard knots or soft knots are required.
Figures 12a and 12d show the possibility of application of a Y-shaped blast air channel
cross-section with corresponding main air channel H and side air channel N. Fig. 12c
shows a further example for the design of an air twist chamber 11' as per the invention.
Figures 13a to 13c show a solution as per the state-of-the-art technology, as produced by
the applicant for already over 20 years. Here one finds a typically long yarn-twisting
chamber with relatively large width and length. This solution was based on the model,
that the yarn could swing out in the yarn-twisting chamber to a very large extent.
Fig. 14a shows a solution as per the invention and as comparison (figs. 14b, 14c) two
solutions as per the state-of-the-art technology. All investigations so far have revealed
that there is a critical dimension for the projection of the air twist chamber. This is
approx. 0.5 mm. In all chamber designs, where the chamber projects by more than
0.5 mm sideways, one can determine a clear reduction in quality. Experiments so far
have shown that the sideways projection of the chamber over the yarn treatment channel
3 should be assessed as critical. It was determined that it is advantageous if the length of
the chamber in the yarn channel in the longitudinal direction is lesser than 1.3 times the
yarn channel width (B).
Figures 15a. 15b and 15c show a comparison of the knots formation: fig. 15a according
to a solution as shown in figures 13a to 13c; fig. 15b according to a solution without
twisting chamber as shown in figures i and 1a; and fig. 15c a solution as per the
invention. In all three solutions, yarns of 80 f 72, 80 f 108, 72 f 72 and 80 f 34 are used.
Depending on the method of operation or the pressure of the blast air, one obtains soft or
hard knots.
Both the figures 16a and 16b show results with comparative experiments - fig. J 6a with
coarse yarn and fig. 16b with fine yarn. The left-side figure always shows the number of
knots per meter, the central figure shows the dispersion of the knots and the right-side
figure shows the stability or the knots-loss under tensile stress. Even nozzles with no
chamber or with round chambers were used (with cup-widths K. of 2.2; 2.4; 2.6; 2.8 mm).
The chamber was designed in cup shape. One can clearly see that the cup-width K of 2.2
mm as per the invention with a real air twist chamber as per the invention, produces the
best result. In all experiments the yarn channel width was 1.6 mm, the yarn channel
depth 1.0 mm and the air blow-in hole 1.1 mm. The advantages as per the invention are
also visible, if additionally elasthane yarns are also introduced into the nozzle and
combined with the filament yarns already mentioned before.
Patent claims
I. Method for producing knotted yarn or twisted yarn from DTY-yarn and/or flat
yarns with a high degree of regularity of knots with the help of air jets, with a
yarn treatment channel and blast air that is blown-in transverse to the yarn
treatment channel, whereby the blast air forms a double twist in the yarn run
direction as well as against the yarn run direction, producing knots,
having the distinctive feature that
the blast air in the inlet region into the yarn treatment channel gets transferred in
an air twist chamber into two strong steady twist flows almost undisturbed by the
filament bundle.
2. Method as per claim 1,
having the distinctive feature that
in the air twist chamber a short region with a steady twist flow is generated, on to
which subsequently follows an alternating twist zone, both in the yarn run
direction as well as against the yarn run direction.
3. Method as per claim 1 or 2,
having the distinctive feature that
for the blast air a pressure of 0.5 to 1.5 bar is used, for producing soft knots that
can get released again during further processing.
4. Method as per claim 1 or 2,
having the distinctive feature that
for the blast air, compressed air of above 1.5 bar is used, for producing hard knots
that do not get released during further processing.
5. Method as per one of the claims 1 to 4,
having the distinctive feature that
yarns with lesser than 10 to 15 dpf, preferably finer than 2 dpf, are treated.
6. Method as per one of the claims 1 to 5,
having the distinctive feature that
the yarn channel cross-section is designed in semicircular shape or U-shape,
whereby the yarn channel width (B) is greater than the yarn channel depth (T).
7. Method as per one of the claims 1 to 6,
having the distinctive feature that
the air twist chamber represents a cup-shaped air channel extension in the yarn
channel and the flow flows through the yarn channel in a shape conforming to the
cross-section.
8. Method as per one of the claims 1 to 6,
having the distinctive feature that
the air twist chamber is designed at least approx. symmetrical to the yarn channel
centre axis and, for producing DTY-yarn, projects over the side yarn channel
walls by 9. Method as per one of the claims 1 to 8,
having the distinctive feature that
the air twist chamber projects beyond the blast air feed channel in yarn channel
longitudinal direction by lesser than 0.5 mm, however max. 22% and min. 5% of
the yarn channel width (B).
10. Method as per one of the claims 1 to 8,
having the distinctive feature that
the air twist chamber is designed in a miniaturized form in such a way, that the
filament bundle cannot penetrate into the sideways extension of the air twist
chamber.
11. Twisting nozzle for producing knotted yarn with high regularity of the knots, with
a continuous yarn treatment channel as well as a blast air feed channel, whereby
the blast air feed channel is aligned to the longitudinal centre axis of the air
treatment channel,
having the distinctive feature that
in the mouth region of the blast air feed channel in the yarn treatment channel a
blast air channel extension is formed for creating an air twist chamber for two
opposite steady twist flows, whereby the blast air channel extension projects by
lesser than 22%, however more than 5%, of the yarn channel width.
12. Twisting nozzle as per claim 11,
having the distinctive feature that
the yarn treatment cross-section is designed as semicircular or U-shaped with a
flat baffle cover.
13. Twisting nozzle as per claim 11 or 12,
having the distinctive feature that
the air twist chamber is designed as a miniaturized cup and is similar in shape
sideways with respect to the yarn treatment channel cross-section.
14. Twisting nozzle as per one of the claims 11 to 13,
having the distinctive feature that
the air twist chamber projects beyond the yarn treatment channel on both sides by
lesser than 0.5 mm.
15. Twisting nozzle as per one of the claims 11 to 14,
having the distinctive feature that
the air twist chamber has a length in yarn channel longitudinal direction that is
lesser than 1.3 times the yarn channel width (B).
16. Twisting nozzle as per one of the claims I I to 15,
having the distinctive feature that
the air twist chamber has a at least approx. circular-symmetrical outer contour and
preferably forms an extension of the centre axis of the blast air channel.
17. Twisting nozzle as per one of the claims 11 to 16,
having the distinctive feature that
for intensifying the sideways air twist formation, the width of the yarn channel
cross-section is greater than the yarn channel depth in the direction of the blast air
feed.
18. Twisting nozzle as per claim 17,
having the distinctive feature that
the treatment channel is designed as a wide channel with a width of preferably 0.6
to 3 mm, ideally with a ratio of yarn channel width (B) to yarn channel depth (T)
of 1.1 to 2.5.
19. Twisting nozzle as per one of the claims 11 to 18,
having the distinctive feature that
the blast air feed channel is designed in a round or oval shape or oval with
triangular character or Y-shaped, whereby the side measurement of the blast air
feed channel is maximum equal to or lesser than the corresponding yarn channel
width.
20. Twisting nozzle as per claim 17 or 19,
having the distinctive feature that
the yarn channel width (B) is greater than the air feed width d, preferably in a
ratio B/d of 1.2 to 3.
21. Twisting nozzle as per one of the claims 11 to 20,
having the distinctive feature that
the yarn channel is formed by a flat slide-able buffer plate and a nozzle plate with
the blast air feed.
22. Twisting nozzle as per one of the claims 11 to 21.
having the distinctive feature that
the yarn channel is designed by means of a nozzle plate and a buffer plate that can
be slid to it, as so-called SlightJet, with an open position of the yarn channel for
threading the yarn and a closed position of the yarn channel for producing a
knotted yarn.
23. Twisting nozzle as per one of the claims 11 to 22,
having the distinctive feature that
the nozzle plate is designed as a plate-like ceramic disc and the ceramic disc along
with the sliding part can be mounted in or dismantled from the twisting nozzle,
and/or that the ceramic disc can be mounted in or dismantled from the sliding part
as change plate.
24. Application of the twisting nozzle as per one of the claims 11 to 23 for producing
knotted yarn from DCF-yarns.

The new invention pertains to a twisting nozzle and a method for producing fine, knotted
yarn with a high regularity of the knots, with the help of air nozzles with a yarn treatment
channel. The blast air is blown in, transverse to the air treatment channel. The blast air
thereby forms a double twist in yarn run direction as well as against the yarn run
direction, for generating the knots. For this, it is suggested that the blast air in the inlet
region into the yam treatment channel gets converted in a short air twist chamber in yarn
channel longitudinal direction into two strong, steady twist flows undisturbed by filament
bundles. In spite of the tiny nature of the air twist chamber, which projects max. 0.5 mm
or 5% to 22% of the yarn channel width (B) beyond the yarn channel longitudinal wall,
the regularity of the knots can be highly improved. It is further possible, depending on
the pressure of the blast air, to generate hard or soft knots that get released again.

A METHOD AND A TWISTING NOZZLE FOR PRODUCING KNOTTED YARN OR TWISTED YARN FROM DTY-YARN AND/OR FLAT YARNS WITH HIGH REGULARITY OF KNOTS

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