EP0321885A1 - Pneumatic nozzle for false twisting - Google Patents

Abstract

In order to improve the efficiency of an air layer which is generated by an air blowing nozzle (5) and circulates in a cylindrical cavity (4) and which is intended to cause the twisting of the yarn introduced through the entry channel (2), on the entry channel (2) there is a tubular extension (3) which forms a guide for the airstream blown in by the blowing nozzle (5). <??>As a result of this guide, the circulating air layer can form before it seizes the abovementioned yarn. <??>It has been shown by means of this measure that the twisting of the seized yarn per unit length of the yarn is increased, and this has led to an increased strength of the yarn, with a low air consumption being obtained at the same time. <IMAGE>

Description

The invention relates to a method according to the preamble of the first method claim and an air nozzle according to the preamble of the nozzle claim. Such a nozzle is from the German design No. 2722319, from European patent application no. 0131170, and also known from German Patent No. 3526514. From these documents it can be seen that such nozzles are used as so-called false twist nozzles in combination with a drafting system, in such a way that the drafting system delivers a sliver that divides the sliver into core fibers and edge fibers. The core fibers are twisted by the twist nozzle or, in the latter prior art, by the second twist nozzle, viewed in the running direction of the yarn, to an incorrectly twisted yarn core, which extends essentially from the twist-generating part of this nozzle up to the exit rollers of the drafting system. The edge fibers are by means of the air inflow channel or in the latter prior art first air nozzle, seen in the direction of the yarn, against the wrongly twisted core and wound around it. These twisted fibers are referred to as wrapping fibers, which wind around the yarn core (with essentially parallel fibers) which has been turned up again after the swirl part of the nozzle and thereby give the yarn the required strength.

It is therefore understandable that the supply of the fibers to the wrongly twisted yarn core and the subsequent winding takes place in such a way that these wrapping fibers are sufficiently saturated and after the yarn core has been turned back into the neutral position (in which the fibers lie essentially in the longitudinal direction in the yarn) lie on the yarn core with sufficient wrap so that the yarn is given the necessary strength.

From the prior art mentioned it can be seen that in the swirl generating part of the nozzle open air injection nozzles, which are directed such that the yarn core coming from the drafting device is given a rotation by this yarn core by the rotating air flow and the resulting centrifugal force against the inner wall of the is brought twist-generating part, so that a crank effect arises on the yarn core, which gives the yarn core the wrong twist, or in the event that two twist nozzles in series, ie one behind the other in the yarn running direction (see DE-PS 3237990) that the first nozzle places the edge fibers on the aforementioned incorrectly rotated yarn core.

Recognizing that this air flow alone leads to the aforementioned crank formation and thus twist of the yarn kernes, special attention was paid in the course of the investigations of this air flow in order to optimize the energy required from the air flow in terms of rotation and economy. The economy should be limited to the comparison between energy consumption and spinning speed.

Furthermore, it is known to the person skilled in the art dealing with these spinning processes that the aforementioned air flow must not only give the yarn a twist, but also a feed in the yarn running direction in order to generate a yarn tension component in the wrongly twisted yarn core.

In addition, it is from European patent application No. 0131170 known (shown in FIGS. 4 to 5a) that the air sucked into the air inflow channel is sucked out in front of the throttle point. It is therefore necessary that the air flow in the swirl-generating part, in addition to the two aforementioned features of this flow, must also create a suction effect in order to suck enough air from the air flow flowing into the supply duct through the inlet duct to the fiber ends lying against the wrongly twisted yarn core not to let it migrate into the suction provided in the inlet duct.

It is therefore an object of the invention to design the air flow in such a way that it is optimally designed with regard to economy and rotation. According to the invention, this object is achieved by the features listed in the characteristics of the first method and first nozzle claim.

Preferred embodiments are defined in the further claims.

The invention is explained for example with the aid of accompanying drawings.

• Fig 1: Eine erfindungsgemässe Dralldüse, halbsche­matisch und im Schnitt entsprechend den Li­nien I-I (Fig. 2) dargestellt,
• Fig 2: einen Grundriss von Fig. 1, im Schnitt ent­sprechend den Linien II-II (Fig. 1) darge­stellt,
• die Fig. 3, 5, 7, 9, 12 und 14: je eine Variante der erfindungsgemässen Dralldüse von Fig. 1, je im Schnitt entspre­chend den in den Fig. 4, 6, 8, 10, 13 und 15 erwähnten Schnittlinien dargestellt,
• Fig 11: Seitenansicht der Dralldüse von Fig. 9, im Schnitt entsprechend den Schnittlinien XI-XI (Fig. 10) dargestellt,
• Fig 16: Falschdralldüse, unter Verwendung einer er­findungsgemässen Dralldüse, halbschematisch und im Schnitt entsprechend den Linien XVI-­XVI (Fig. 17) dargestellt,
• Fig 18: Falschdralldüse mit zwei erfindungsgemässen Dralldüsen, im Längsschnitt dargestellt.

It shows:

• 1: A swirl nozzle according to the invention, shown semi-schematically and in section along lines II (Fig. 2),
• 2: a floor plan of FIG. 1, shown in section along lines II-II (FIG. 1),
• 3, 5, 7, 9, 12 and 14: each a variant of the swirl nozzle according to the invention from FIG. 1, each shown in section according to the cutting lines mentioned in FIGS. 4, 6, 8, 10, 13 and 15,
• 11: side view of the swirl nozzle of FIG. 9, shown in section along the section lines XI-XI (FIG. 10),
• 16: false twist nozzle, using a swirl nozzle according to the invention, shown semi-schematically and in section along lines XVI-XVI (FIG. 17),
• Fig. 18: False swirl nozzle with two swirl nozzles according to the invention, shown in longitudinal section.

1 shows a swirl nozzle 1 with an inlet channel 2, which forms the inside diameter of a tube, the extension 3 of which protrudes with a length 1 into a cylindrical cavity 4 provided in the swirl nozzle 1. Furthermore, an air injection nozzle 5 merges with the outlet mouth 6 into the cylindrical cavity 4 such that, seen with a view of FIG. 1, the outlet mouth 7 of the inlet channel 2 is lower than the outlet mouth 6 of the air injection nozzle 5. This creates between the cylindrical inner wall 8 of the cavity 4 and the substantially cylindrical outer wall 9 of the tubular extension 3 an annular air duct for the air flow blown through the nozzle 5.

The air injection nozzle 5, seen with a view of FIG. 1, is arranged on the one hand at an angle such that the axis of symmetry 10 of the injection nozzle 5 has an imaginary plane 11 which intersects the axis of symmetry 10 and, with a view of FIG. 1, perpendicular to the cutting surface and is to the longitudinal axis of this figure, forms an angle α and on the other hand, as shown in Fig. 2, opens tangentially into the cavity 4. As a result of this position of the injection nozzle 5, the air stream that is blown in creates an air layer that runs around the cylindrical inner wall 8 and shifts in the direction of arrow A.

The flow direction A creates a negative pressure in the inlet channel 2, according to the jet pump principle, which sucks air through the inlet channel 2 in the direction of the arrow A.

By means of this air sucked in through the inlet duct 2, fibers are sucked through the inlet duct 2, as is known from the prior art mentioned, and are captured by the surrounding air layer the. If, as mentioned in the prior art mentioned, the swirl nozzle is used as a so-called false twist nozzle, a centrifugal force arises in the detected yarn core, which deflects the yarn core in the form of a crank. A yarn core deflected in this way rotates in the manner of a rotating crank, as can best be seen from layout no.

In the aforementioned prior art, the tube extension 3 protruding with the length 1 is missing, and the injection nozzles are mounted in such a way that the crank-like rotating yarn core interferes with the structure of the surrounding air layer, since the outlet opening is periodically covered by the rotating yarn crank, since the inflowing air is not forced to form a circumferential layer of air before it catches the yarn core.

This disadvantage has the effect that, with the same amount of air and the same blowing speed, the twist in the yarn core is smaller and the suction effect is less than with the use of the tubular extension 3 according to the invention Case the speed of the blown air corresponds to the speed of sound.

If this air speed is further disturbed by types of execution according to the prior art or. reduced, so there are losses in relation to the efficiency of the injected energy.

As is known from the prior art, the the rotating yarn core is wound by winding fibers which, even after the wrongly twisted yarn core has been untwisted, ensure that the core fibers lying essentially in the axial direction of the yarn are held together in order to thereby produce a usable yarn.

Such a yarn is, as can be seen from the prior art mentioned, drawn off by a pair of draw-off rollers and fed to a winding device. By pulling off the yarn by means of said pulling roller pair on the one hand and by the aforementioned rotation of the wrongly twisted yarn on the other hand, in the area after the cylindrical cavity 4, i. after the swirl-producing part of the swirl nozzle, a so-called helix formation in the yarn, which continuously decreases towards the pair of draw-off rollers.

In order to give guidance to such a helix, at least initially, as seen in the direction of arrow A, an expanding cone 12 is provided after the cylindrical cavity 4 and has a predetermined length (not shown).

The following FIGS. 3 to and 15 show variants of the swirl nozzle according to the invention, which is why the same or essentially the same elements are provided with the same reference numerals or with a decimal place. The dimensions of such elements shown can differ from FIG. To FIG.

In the aforementioned sense, FIGS. 3 and 4 show an air nozzle 1 according to FIG. 1, but with an inlet duct 20 which is not essentially as in FIG. 1 a cylindrical, but has a shape at least similar to a Venturi tube.

The advantage of this "venturi shape" lies in the smaller resistance for the amount of air to be sucked through and also offers the possibility of choosing the narrowest duct cross-section with constant air resistance, in order to create a balloon above the swirl nozzle as required, as seen in FIG. 3 , to prevent. Furthermore, the pipe extension has a mouth edge that is relatively narrow and thus leads to improved airflow and avoids turbulence.

Furthermore, it is shown with the length 1.1 that the tube extension 3.1, which projects into the cylindrical cavity 4, projects further into the cavity with a length 1.1 than with the length 1.

FIG. 5 shows a further variant in which a narrowing cone 30, viewed in direction A, is connected to the cylindrical cavity 4.1, by means of which the circumferential air layer blown in through the injection nozzle 5 and formed in the cavity 4.1 is narrowed, as a result of which the speed of rotation thereof circulating air layer is increased, with the advantage that the fibers captured by the air layer circulate at a correspondingly higher speed.

Another advantage of this embodiment is that the narrowing of the air layer means that the fibers sucked in through the inlet channel 2 come into contact with the surrounding air layer more quickly.

An expanding cone 12.1 is connected to the cone 30 and has the same function as the cone 12 of FIGS. 1 and 3.

FIG. 7 shows a variant of FIG. 5, in that a constriction 40 is provided instead of the cone 30, which together with the cone 12.1 connected thereto has a shape similar to the Venturi nozzle principle.

The advantage of the shape should be that of the Venturi nozzle, namely to improve the flow resistance of the air flow in the direction of arrow A and to provide a smoother transition from the narrowing cone 40 to the expanding cone 12.1.

FIG. 9 shows a further variant of the swirl nozzle of FIG. 1, in that the tubular extension 3 has an annular extension 50 (not shown in section in FIG. 11), which is provided with at least one helical groove 51.

The annular extension 50 forms a compressed air space 52 with a height B in the cylindrical cavity 4. The two, for example, provided grooves 51 (only one visible in FIG. 11) connect this compressed air space 52 with the part following the annular extension 50, in direction A. seen, the cylindrical cavity 4th

The compressed air space 52 can be supplied with compressed air by means of a connecting bore 53.

During operation, this compressed air flows through the helical grooves 51 into the lower part of the cylindrical cavity 4 and forms a circumferential layer of air through the helical shape of the grooves 51, which also moves in the conveying direction A.

It goes without saying that one or a plurality of helical grooves can be provided as required.

It should also be pointed out that the bore 53 does not necessarily have to open tangentially into the compressed air space 52, as is shown in FIGS. 1 to 8, since the rotation of the air layer is caused by the grooves 51.

The compressed air space 52 can also be enlarged as desired in order to reduce the air speed therein and to improve the air distribution in the case of a plurality of grooves 51.

FIG. 12 shows a variant of the swirl nozzle of FIG. 9, in that a conically shaped, annular extension 60 is provided instead of the cylindrical, annular extension 50.

In this extension 60, one or more helical grooves 61 are also provided, which have the same function as the grooves 51 in FIGS. 9 to 11.

The extension 60 fits into a narrowing cone 62, which is followed by an expanding cone 63.

For purely technical reasons, the tube extension 3 is provided, for example, in an end plate 64 which is tightly connected to the nozzle body 65.

in operation, the compressed air space 52 is supplied with compressed air by means of the bore 53, which passes through the helical grooves 61 into the narrowing cone 62 and forms a circumferential air layer therein, the speed of which increases with increasing constriction. To improve the air flow, the widening 60, seen in the direction of conveyance A, can be connected to a narrowing cone 66, the narrowing angle α of which can be determined empirically. A narrow mouth edge can also be achieved here.

14 and 15 show a variant of the swirl nozzle of FIGS. 5 and 6, in that the tubular extension 3 additionally has a conical extension 70 which extends to the narrowest diameter of the cone 30. The extension 70 also has a narrow mouth edge. This creates an annular space with a conical cross-section. The widening cone 12.1 follows the cone 30

The ratio length to diameter of the conical extension 70 or. of the cone 30 can be empirically optimized with regard to the desired acceleration of the air flow.

Above the cone 30, as seen in FIG. 14, an air injection nozzle 5.1 opens tangentially into the cylindrical cavity 4.1, the angle α (see FIG. 1) being essentially 0 degrees (not particularly marked in FIG. 14).

With this arrangement of the two coaxial cones, the compressed air blown in through the air injection nozzle 5.1 is first circulated and secondly accelerated by the narrowing conical ring cross-section 71 in the direction of travel A, so that in the room immediately after the cone 30 or. the cone 70 a umlau air layer is created, which also moves in the conveying direction A.

16 and 17 show a possible application of the air nozzle shown in FIGS. 1 and 2, it being mentioned that all swirl nozzles shown in FIGS. 1 to 15 could be used in this example.

The example shown with FIGS. 16 and 17 corresponds to a modification according to the invention of the false twist nozzle shown in German Design No. 2722319 (St. d. T. mentioned at the beginning). Instead of this nozzle, the swirl nozzles shown in European patent application No. 0131170 (mentioned at the beginning of St. T.) could also be used.

16 shows a hint of an output roller pair 80 of a drafting system (not shown further) and a false twist nozzle body 81.

The false twist nozzle body 81, viewed in the direction of conveyance A, comprises a feed channel 82, the inlet channel 2 with the tubular extension 3 and the cylindrical cavity 4, the air injection nozzle 5 and an expanding cone 12 connected to the cavity 4.

The air layer circulating in the cavity 4 sets the yarn core 83 in rotation, as already described in the prior art mentioned, so that a false twist which extends against the pair of output rollers 80 occurs therein.

In the widening cone 12, the yarn experiences a helix formation and then the swirl of the yarn core 83. The yarn is then drawn off by a pair of draw-off rollers (not shown) and fed to a winding device (not shown).

FIG. 18 shows a further possible application of the swirl nozzles shown with FIGS. 1 to 15. The example shows a false twist nozzle modified according to the invention from German laid-open specification DE 3526514 (St. d. T. mentioned at the beginning). This example shows a pair of output rollers 90 of a drafting system (not shown) and a false swirl nozzle body 91 with a first swirl nozzle area 92 and a second swirl nozzle area 93.

The swirl nozzle of the region 93 serves to produce an incorrectly twisted core of yarn which extends in a manner known per se against the pair of output rollers 90, and the swirl nozzle of the region 92 serves in a manner known per se to wind the edge fibers around the incorrectly twisted yarn core.

It should also be mentioned in connection with this example that, even if the air nozzle of FIGS. 1 and 2 are used in this variant, for example, all further variants, be it in the first or second nozzle region, can be used.

For the sake of simplicity, the further details of this variant should not be mentioned further, but reference should be made to the prior art mentioned.

Finally, it should be mentioned that within the variants shown in FIGS. 1 to 15, variations among one another can be selected, for example that the inlet channel 20 is also used in the other examples 7, or that the venturi shape shown in FIG. 7 can also be combined with the variants shown in FIGS. 12 and 14.

Likewise, the examples shown are not limited to a single injection nozzle 5, but it goes without saying that a plurality of injection nozzles 5 which are uniform or distributed unevenly on the circumference can be used.

Claims (19)

1. Method for generating a circumferential air layer in a swirl-generating part of an air nozzle, by means of which fibers are brought into a rotational movement,
characterized,
that this air layer is formed before it catches the fibers. 2. The method according to claim 1,
characterized,
that the fibers form a yarn that is preferably rotated. 3. The method according to claim 1,
characterized,
that the fibers form a yarn core of a so-called false twist yarn. 4. The method according to claim 1,
characterized,
that the fibers are the wrapping fibers of a wrongly twisted core of a so-called false twist yarn. 5. The method according to claim 1,
characterized,
that the air layer conveys to the fibers, in addition to the twist-imparting component, a component in the conveying direction, which preferably runs in the yarn running direction. 6. The method according to claim 1,
characterized,
that the air layer is directed by guide elements, and that the air layer is preferably for suction gene transport air, is used on the principle of the jet pump, by means of which the fibers are transported into the swirl generating part so that they can be detected by the air layer. 7. swirl nozzle with a central inlet channel, an adjoining swirl-generating part of round cross-section, and with at least one air blowing means provided in this part for blowing in an air stream to form a circumferential air layer in this part and for sucking fibers into this part,
characterized,
that an air duct is provided in the swirl-generating part in such a way that the air flow forms into a circumferential air layer before it detects the sucked-in fibers. 8. swirl nozzle according to claim 7,
characterized,
that the air injection means is at least one air injection nozzle which opens tangentially into the swirl-generating part and that the air duct is such a pipe protruding into said part that the air flow is guided between the inner wall of said part and the outer wall, the pipe preferably at least extends so far into the entrance area that the tube, seen in the direction of a longitudinal section of the tube, covers the mouth of the air injection nozzle. 9. swirl nozzle according to claim 8,
characterized,
that the outer wall of the tube and the inner wall of the swirl-generating part are cylindrical. 10. swirl nozzle according to claim 9,
characterized,
that the air injection nozzle is provided in such a way that the blown-in air flow essentially flows along the inner wall of the input area and that the distance between the inner wall of the input area and the outer wall of the tube is selected such that the air flow is seen in the circumferential direction at least after flowing into the input area undergoes no expansion. 11. swirl nozzle according to claim 9,
characterized,
that the swirl generating part has a conical widening after the cylindrical inner wall. 12. swirl nozzle according to claim 9,
characterized,
that the swirl-generating part has a constriction after the cylindrical inner wall, an expansion preferably adjoining the constriction and the constriction in particular having a cone with a rectilinear surface line, the constriction and expansion advantageously being able to be designed at least similar to the venturi tube principle. 13. swirl nozzle according to claim 7,
characterized,
that the inlet channel is essentially cylindrical or has the shape of a Venturi tube. 14. swirl nozzle according to claim 7,
characterized,
that the swirl generating part comprises a cylindrical inner wall, that the air injection means a in this inner wall projecting and guided by the inner wall is a cylindrical ring body, the inner wall of which is a continuation of the inlet channel and that the ring body, as said air duct, comprises at least one helical groove through which said air flow is blown into the swirl-generating part. 15. swirl nozzle according to claim 7,
characterized,
that the swirl-generating part comprises a conical inner wall, that the air blowing means is a conical ring body lying against this inner wall, the inner wall of which is a continuation of the inlet channel, and that the ring body, as the air duct, comprises at least one helical groove through which the air flow into the swirl-generating part is blown. 16. swirl nozzle according to claim 14 and 15,
characterized,
that above the ring body, as viewed in the direction of the figures, an air space is provided in which an overpressure is generated to generate the air flow mentioned. 17. swirl nozzle according to claim 15,
characterized,
that a diffuser-shaped channel is connected to the conical inner wall. 18. swirl nozzle according to claim 7,
characterized,
that the swirl-generating part comprises an annular cavity surrounding the inlet channel in the form of a funnel, the annular outlet mouth of which is essentially at the same height Direction seen on the figure, as the outlet mouth of the inlet channel, and that a diffuser-shaped channel is then connected to the outlet mouth of the funnel. 19. Use of the swirl nozzles according to claims 7 to 17, in a so-called false twist nozzle, for producing a so-called false twist yarn, with either two twist nozzles in series, i.e. one behind the other, as seen in the yarn running direction, are provided, the swirl nozzles being the same or different depending on the purpose, but are provided according to one of the preceding claims.

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