EP0539808B1 - Apparatus for stuffer crimping synthetic filament yarns - Google Patents

Description

The invention relates to an apparatus for upsetting synthetic filament threads according to the preamble of patent claim 1.
This device is known from EP-189099-B.

In the known texturing nozzle, the flow channel downstream of a nozzle needle, in which the filament threads are guided together with the outflowing pressure medium, is formed with a cylindrical, in particular circular-cylindrical cross section and with a constant diameter over its length.
The known texturing nozzle has proven itself particularly in machines for carrying out a continuous spin-stretch texturing method and is used for the crimping of synthetic filament threads made of polyester, in particular polyethylene terephthalate, PA6, PA6.6 or PP at stretching speeds behind the spinning stage from 1800 to 3000 m / min applied industrially with great success. At this speed, however, a limit to the production speed is reached because the thread tension on the bundle of filaments conveyed by the nozzle decreases and any thread entanglement leads to a winder formation on the draw godets and to uncertainties in the production process.

The object of the invention is therefore the device for Compression crimp according to the preamble of claim 1 structurally to improve in such a way that the specified technical upper limit for a safe exercise of compression crimping is shifted further upwards according to the known, continuous spin-stretch texturing method and that at a further increased thread speed there is still sufficient tensile force is exerted by the nozzle on the running thread. It should be taken into account that the high quality already achieved with regard to thread crimping, consistency and dissolvability of the thread plug is maintained and the pressure medium consumption and pressure is as low and economical as possible.

The solution to the problem results from the characterizing part of patent claim 1 in connection with its preamble. As a result of the specified measure, the speed of sound is reached in the flow channel common to the filament bundle and the escaping pressure medium in the drag flow, which is at least maintained in the widening part of the flow channel or increases further. As a result, an increased thread tensile force is exerted on the filament threads, which allows thread speeds of 4000 m / min behind the stretching godets with a high degree of operational reliability, and this without increasing the working pressure of the pressure medium and the associated risk of blowing out the thread plug from the stuffer box connected to the flow channel.

From DE-27 53 705 and DE-17 85 158 a compression ruffling device with a blowing nozzle is already known, in which the pressure medium flowing out reaches the speed of sound and supersonic speed in an expanding channel. In this device, the flow channel is at the point where the flow of the pressure medium meets the supplied filament threads, in cross section, however, suddenly enlarged and then remains unchanged in cross section up to the stuffer box. Apart from the fact that the nozzle is operated at much higher pressures up to 40 bar - in the examples 14 to 15 bar - the supersonic flow breaks down due to the very large expansion of the flow channel and the compression shock occurring there, and the drag effect on the filament threads is strong back. Due to the high working pressure of the pressure medium, there is also the risk of the thread plug blowing out of the stuffer box and crater formation when the thread plug is formed, which in turn is associated with poor dissolvability.

Experiments with the texturing nozzle mentioned at the outset had shown that in channels with a constant cross section and small diameter, a supersonic flow can only be maintained over a very short distance. In contrast, it was found that a small widening angle adapted to the friction conditions in the flow channel allows a supersonic flow over a longer distance.

Although it is possible to end the flow channel by a sudden cross-sectional expansion in the stuffer box, it is preferred according to claim 2 to make the transition from the flow channel into the preferably cylindrical or slightly conically expanding stuffer box in a short, separate section, the one has greatly enlarged cone angle. This results in a gradual flow widening in this area up to the cross section of the stuffer box, in which a radial force component acts on the filament threads. This also results in a more even thread placement across the entire stuffer box cross-section. A crater formation in the freshly formed thread plug is successfully counteracted.

It is pointed out that the last-described section of the nozzle upstream of the stuffer box in terms of length and shape of the widening clearly differs from the flow channel in which the pressure medium and the filament threads meet and in which the large forces of the flow are transmitted to the filament threads by frictional forces is to be distinguished.

The flow channel advantageously has a length of more than 30 and preferably more than 40 times the channel cross section at its narrowest point. As a result, the forces are transmitted to the filament threads over a long length at which the supersonic speed is present in the pressure medium flowing out. Through impulse transmission from the drag flow enveloping them, the filament threads achieve a very high conveying speed, for example when they are drawn off freely from a supply spool, or when the filament speed is limited by the delivery speed of the stretching godets, the nozzle achieves a high thread tension by this measure.

The advantage of a very small opening angle of the flow channel according to claim 4 is that with a very narrow flow channel cross section and the wall friction that is necessarily to be taken into account, the supersonic speed is maintained even with a large overall length of the flow channel without flow breaks. This means that it is possible to advantageously avoid the occurrence of a surge in the flow. The impulse and energy transfer to the filament threads takes place with a particularly high efficiency.

The measure according to claim 5 offers the advantage that after When the speed of sound is reached in the narrowest point of the flow channel, the outflowing pressure medium in the flow channel is initially accelerated. This acceleration preferably takes place up to an optimum that is at a Mach number of Ma = 1.4. The following stage of the flow channel is designed so that the flow rate is kept substantially constant.
As a result, the desired supersonic speed is achieved over a short distance, which is maintained in the subsequent, weakly divergent line, without one or more compression shocks occurring.

Claim 6 specifies a preferred embodiment of the flow channel.

Claim 7 specifies a further dimensioning rule, the result of which is a limited consumption of the pressure medium, which is particularly economical for the achievable thread speed.

The thread inlet channel of the high-speed nozzle is particularly advantageously formed in a nozzle needle according to claim 8. This has the advantage of a better and easier adjustment of the blowing channel to adjust the thread tension.

The advantage of the constructive design of the nozzle downstream of the flow channel according to claim 9 is that the nozzle is simple to set up and maintain, in particular it can be cleaned of thread remnants. Another advantage lies in the annular slot flow formed between the truncated cone of the nozzle needle and the nozzle body, which has a radial component and which the filament threads after the thread inlet channel and the Blow duct tightly encloses on all sides.

A nozzle according to claim 10 in conjunction with claim 1 or 9 is formed in that the nozzle needle containing the thread inlet channel is sealingly inserted into the nozzle body by means of a sealing thread and possibly with the interposition of spacers (for example DE-U 80 22 113, DE-U 77 23 587). In this arrangement, the cross section of the ring slot for the emerging pressure medium can be adjusted by changing the axial setting of the nozzle needle and nozzle body. Furthermore, by varying the opening angle on the nozzle body and / or the cone of the nozzle needle according to claims 11 to 13 in conjunction with the axial adjustability of the nozzle needle according to claim 10 can be achieved that the narrowest point of the flow channel is axially displaced and the pressure conditions at the beginning of Flow channel can be adjusted so that the blowing nozzle sucks the filament threads at the inlet of the thread inlet channel, or that the blowing nozzle blows out small amounts of the pressure medium through the thread inlet channel. In a specific embodiment of the nozzle, it is advantageously designed such that it can be switched over by the axial adjustment of the nozzle needle from the suction mode when the filament threads are put into an operating state with the nozzle easily blowing out pressure medium at the thread inlet channel.

Finally, it is the advantage of the measure according to claim 14 that the filament threads can simply be inserted into the blow nozzle, which is particularly necessary when starting up the texturing device and after a thread break on the stretching godets, after changing the spinneret, etc. and greatly reducing the handling times.

The invention is explained in more detail below with reference to a drawing which represents an embodiment of the invention.

Fig. 1

eine Blasdüse mit angeschlossener Stauchkammer im Längsschnitt;

Fig. 2

eine in Längsrichtung geteilte Stauchkammerkräuselvorrichtung gemäß der Erfindung in abgeänderter Ausführung;

Fig. 3

einen Querschnitt der Düse nach Fig. 2 im Bereich der Druckmittelzufuhr;

Fig. 4

den Strömungskanal mit Filament- und Druckmittelzufuhr in vergrößerter, schematischer Darstellung;

Fig. 5

verschiedene Ausbildungen des Strömungskanals im Bereich;

und

Fig. 6

des stromabwärtigen Endes der Düsennadel.

Show it:

Fig. 1

a blow nozzle with attached stuffer box in longitudinal section;

Fig. 2

a longitudinally divided stuffer box crimping device according to the invention in a modified version;

Fig. 3

a cross section of the nozzle of Figure 2 in the region of the pressure medium supply.

Fig. 4

the flow channel with filament and pressure medium supply in an enlarged, schematic representation;

Fig. 5

different designs of the flow channel in the area;

and

Fig. 6

the downstream end of the nozzle needle.

In Fig. 1, a compression crimping device is shown in longitudinal section, which essentially corresponds to the device known from EP-189099-B (Fig. 17 and Fig. 19). It consists of the nozzle body 1 with an insert body 3 containing the flow channel 2, as well as the inlet-side nozzle needle 4 and the stuffer box 5 flanged on the outlet side of the nozzle body 1 and take-off roller 6 for the thread plug 7 formed in the stuffer box 5 (FIG. 2). The nozzle needle 4 contains the central thread inlet channel 8 and the pressure medium supply. It is screwed into the insert body 3 in an axially adjustable manner with a fine thread 9 and is sealed by cover 10 against pressure medium losses. The pressure medium supply, for example heated compressed air, water vapor, preferably superheated water vapor at a pressure of about 7 to 12 bar, takes place through distribution channel 11 in the nozzle body 1. The distribution channel 11 with the blowing channels 15 is via axial channels 12, annular groove 13 in the cover 10 and radial bores 14 connected, which open at the downstream end of the nozzle needle 4 in the common flow channel 2 for the pressure medium and the filament threads.

The flow channel 2 consists of a first section 2.1, with the length L 1 which tapers in the flow direction up to a narrowest cross section 2.2 and then widens conically in a second section 2.3 with a length L 2, with a very small opening angle alpha (Fig. 4), which is preferably less than 2.0 °. The stuffer box 5 is flanged to the nozzle body 1 with a flange 35 and screws 16. On the inlet side, it initially has a section with a conical channel widening 17 from the cross section of the flow channel 2 into the circular cylindrical or slightly conical cross section of the stuffer box 5. The cone angle beta of the channel widening 17 is preferably approximately 10 °. An area follows in the direction of flow, which is permeable in the radial direction so that the pressure medium can be separated from the filament threads in the stuffer box 5. This area consists of closely arranged ribs 18 which are formed by the incisions 19 in the stuffer box wall 20 and which are so closely adjacent that parts of the thread plug 7 formed do not get caught on the ribs 18. The outlet-side end of the stuffer box 5 is circular-cylindrical or slightly conical to form a thread plug 7 with a circular cross section. Arranged opposite the outlet is a semicircular profiled, continuously adjustable take-off roller 6 which interacts with a second roller, not shown. Over the entire length of the device, it has a threading slot 21 which can be opened and closed during operation by means (not shown here) for inserting the filament threads so that individual filaments are not blown out of the slot 21. For further details, reference is made to the already mentioned EP-189099-B.

Fig. 2 shows a modified upsetting chamber in the open state. There are components with the same function as in Fig. 1 provided with the same reference numerals. The longitudinally divided nozzle needle 4 is fastened here to the nozzle body 1 by screws 36. The pressure medium supplied through radial channel 22 on the nozzle body 1 in the direction of arrow 23 flows through a conical annular slot channel 24 into the flow channel 2 and there meets the filament threads fed through the thread inlet channel 8, which are compressed in the stuffer box 5 to the thread plug 7 and transported away by the take-off roller 6 and roller 6.1 become.

The crimping device shown is divided into two halves 1.1 and 1.2 for cleaning or threading the filament threads in the longitudinal direction and one half 1.2 is moved to close in the direction of arrow 25, centering cams 26 on one nozzle half 1.2 in associated center holes 27 of the other nozzle half 1.1 intervene and operate locking means, not shown. By acting on a pressure chamber 28 with pressure medium in direction 30, the two nozzle halves 1.1, 1.2 are pressed together, sealed in the longitudinal direction and a radial outflow of the working medium is prevented.

Fig. 3 shows the cross section of the compression chamber in the area of the pressure medium supply 22 and the annular chamber 29, which opens into the annular slot channel 24 on the outer circumference of the nozzle needle 4.

4, the flow channel 2 in the insert body 3 of the nozzle body 1 of the stuffer box crimping device is shown enlarged. In a first section 2.1, it tapers in the form of a nozzle, to a point 2.2 at which the channel has its narrowest cross section and the flow reaches the speed of sound. The nozzle needle 4 projects axially into the first section 2.1 inside. It is axially adjustable in the direction of arrow 34. The filament threads are fed through the central channel 8 and the pressure medium is supplied through the conically tapering annular slot 24 formed between the nozzle needle 4 and insert body 3. Downstream of the narrowest point 2.2 there is an increase in the flow cross section of the flow channel 2 in section 2.3. This can take place either continuously at a cone angle alpha of less than 5 °, preferably less than 3 ° and in particular between 1 ° and 2 °. However, it can also take place in at least two stages, namely in a first stage with a larger and a second stage with a cross-sectional expansion that is smaller than the first. The size of the widening angle alpha is fundamentally also dependent on the quality of the mechanical processing of the channel wall and is produced with the poorer processing quality of the flow channel 2 with the larger cone angles alpha.
The length L₂ of the flow channel section 2.3 is dimensioned depending on the diameter of the flow channel 2 at the point of the narrowest cross section 2.2. With a diameter of less than 3 mm at the narrowest cross-section 2.2, a length L₂ between 30 and 40 times this diameter with a pre-pressure of the blowing medium of approx. 6 bar gives the best results in terms of thread speed and texturing. With a higher pre-pressure of the blowing medium, even greater lengths L₂ are advantageous in order to achieve even higher thread tensile forces.

In the case of a flow channel 2, which is continuously expanded in two stages downstream of the narrowest point 2.2 (not shown), the length of the section with the smaller opening angle is preferably more than 8 times as long as the length of the first section with the larger opening angle.

The last section of the flow channel is the channel widening 17 with a significantly larger cone angle beta, beta being approximately 5 to 15 °. This section is flowed through by subsonic flow after the occurrence of small compression surges.

Since the filament threads in this area of the channel widening have almost reached the stuffer box 5, the drop in speed does not play an important role at this point. The length L _{D of} this section results from the diameter of the flow channel 2.3, at its end, the cone angle beta and the intended diameter of the stuffer box 5.

FIGS. 5 and 6 show the flow channel 2 in the region of the mouth of the axially adjustable nozzle needle 4. 5, the conical annular slot channel 24 is formed in the nozzle body 1 with a cone angle rho. It merges at point 31 into the section 2.1 of the flow channel 2 which tapers in the shape of a nozzle and which has the narrowest flow cross section at point 2.2. The nozzle needle 4 is formed with a cone angle gamma which differs from the cone angle rho in the nozzle body 1 and is smaller than this. As a result, the nozzle needle 4 can be displaced axially into the flow channel by the length s beyond the point 31. A narrowest cross section of the annular slot channel 24 can thus be placed in front of the downstream end of the nozzle needle 4 at the point 31. This influences whether and in what quantities pressure medium emerges upstream through the thread inlet channel 8 of the nozzle needle 4.

In FIG. 6 the nozzle needle 4 is designed in a modification of the situation in FIG. 5 in such a way that the surface is formed from two conical surfaces, the upstream one of which has an opening angle gamma and the downstream one of which Has opening angle epsilon. By forming the surface of the nozzle needle 4 from two conical surfaces meeting at the circumference 32 with a different cone angle, the annular slot channel 24 and the pressure conditions in the annular slot channel 24 and in the thread inlet channel 8 can also be influenced such that the blowing nozzle does not blow backwards.

Claims (14)

1. Apparatus for stuffer crimping synthetic filament yarns having a nozzle which can be charged with a heated gaseous or vaporized pressure medium and a stuffing box (5) adjoining said nozzle, in which apparatus the filament yarns are supplied through a yarn inlet duct (8) and the pressure medium is supplied through at least one blast duct (15, 24), preferably an annular slot (24) formed on the generated surface of a straight circular cone, and are conveyed through a flow duct (2) in which the filament yarns are guided together with the pressure medium into a stuffing box (5) of which the cross-section is greatly widened relative to the flow duct (2) and in which the pressure medium is discharged through radial discharge openings (19) and the filament yarns are compressed to form a yarn plug (7) which can move along the stuffing box (5), characterized in that the cross-section of the flow duct (2) - viewed in the direction of flow - decreases to a very narrow cross-section (2.2) in which the speed of sound is reached in the pressure medium and from there to the stuffing box (5) increases continuously, substantially with a constant aperture angle (α) or discontinuously in at least two stages.
2. Apparatus according to Claim 1, characterized in that the flow duct (2) is connected by a portion comprising a duct widening (17) and having a cone angle (β) of less than 20° to the stuffing box (5) which is preferably cylindrical or widens slightly conically.
3. Apparatus according to Claim 1 or 2, characterized in that the length of the flow duct (2) is more than 30 times, preferably more than 40 times, the diameter at the narrowest duct cross-section (2.2).
4. Apparatus according to Claims 1 to 3, characterized in that the aperture angle (α) of the flow duct (2.3) downstream of the narrowest duct cross-section (2.2) is less than 3°, in particular between 1° and 2°.
5. Apparatus according to at least one of Claims 1 to 4, characterized in that the flow duct (2.3) downstream of the narrowest cross-section (2.2) is widened more greatly in a first stage and is widened in a second stage less than in the first stage in such a way that the flow speed in the first stage is preferably accelerated to 1.4 Mach and is kept substantially constant in the second stage.
6. Apparatus according to Claim 5, characterized in that the second stage is at least five times and preferably more than eight times as long as the first stage.
7. Apparatus according to any one of Claims 1 to 6, characterized in that the diameter of the flow duct (2) is less than 3 mm at its narrowest point (2.2).
8. Apparatus according to any one of Claims 1 to 7, characterized in that the yarn inlet duct (8) in the upstream end of the nozzle body (1) is formed in a nozzle needle (4); and in that the blast duct (15, 24) surrounds the nozzle needle (4) in an annular manner and opens at the downstream end of the nozzle needle (4) coaxially to the yarn inlet duct (8).
9. Apparatus according to any one of Claims 1 to 8, characterized in that the nozzle needle (4) at the downstream end of the yarn inlet duct (8) is in the form of a straight truncated cone - with an imaginary tip pointing in the direction of flow - which can be inserted sealingly into a recess in the nozzle body (1) leaving an annular slot (24) for the outflowing pressure medium.
10. Apparatus according to Claim 9, characterized in that the nozzle needle (4) in the nozzle body (1) can be adjusted axially in order to alter the annular slot (24).
11. Apparatus according to Claims 9 and 10, characterized in that the aperture angle (ρ) of the conical recess of the nozzle body (1) is larger than the aperture angle (γ) of the nozzle needle (4).
12. Apparatus according to Claims 9 to 11, characterized in that the generated surface of the truncated cone of the nozzle needle (4) consists of two conical surfaces with cone angles (γ, ε) which differ from each other, the larger cone angle (ε) following the smaller cone angle (γ) viewed in the direction of flow.
13. Apparatus according to Claim 9, characterized in that the flow duct (2.1) tapering to its narrowest cross-section (2.2) directly adjoins the recess, of the nozzle body (1), which differs with respect to its conicity; and in that the nozzle needle (4) is inserted axially into the recess in the nozzle body (1) in such a way that its downstream end extends axially into the flow duct (2) and in the upstream region of the annular slot (24) a very narrow flow cross-section is formed between the nozzle needle (4) and the nozzle body (1).
14. Apparatus according to any one of Claims 1 to 13, characterized in that the nozzle body (1), nozzle needle (4), flow duct (2) and stuffing box (5) are divided in the longitudinal direction and can be opened and closed for inserting the yarn.

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