EP0208274B2 - Method and device for spinning yarn according to the open-end-friction spinning technique - Google Patents

Description

The invention relates to a method and a device for spinning a yarn or the like, according to the open-end friction spinning principle, as in the preamble of the first method or. of the first device claim is defined.

From previous publications on the open-end friction spinning process, it is known to dissolve a sliver into individual fibers by means of an opening roller known from the rotor-open-end spinning method, in that these fibers are combed out from the needles or teeth of the opening roller at a high peripheral speed and a conveying air flow handed over to a friction device for transport.

This creates a tangle of undrawn fibers in the conveying air flow, which, if delivered to the friction spin material in this state, provide poor conditions for a yarn of usable quality.

A proposal to deliver these fibers in a stretched state is known from German Offenlegungsschrift No. 3 324 001. Obstacles, e.g. in the form of needles inclined in the conveying direction, provided in the conveying channel, on which the fibers remain temporarily stuck or at least braked and thereby to be stretched by the air stream in order to be released in this stretched state for yarn formation.

The disadvantage of such obstacles is primarily the risk that at least temporarily larger fiber accumulations form at the obstacles, which can be conveyed as a whole and delivered to the end of the yarn, which leads to unusable nits in the yarn. The other danger is the possibility of at least partial blockage of the delivery channel.

Another proposal to deliver the fibers in a stretched and as parallel as possible position in the gusset gap of two friction spinning drums is known from German Offenlegungsschrift No. 3 318 924. In it, a slot-shaped fiber conveying channel has a bulge in the region of the mouth on the wall opposite the gusset gap, in order to give a possibility of being delivered in a stretched form after the front end thereof has been gripped in the gusset gap by the yarn end and pulled off in the opposite direction in a so-called spin-stretch movement, lay parallel to the end of the thread in a whip-like manner, in order then to be twisted into a thread. The fiber feed channel lies essentially in a plane that is laid through the gusset gap and perpendicular to the axes of the rollers. In addition, the fiber conveying channel is at an acute angle and is inclined at an angle of approximately 30 ° against the direction in which the yarn is drawn off.

The disadvantage of this device is that the fibers, after they have been gripped in the stretched position with their front end by the yarn end, are deflected at a pull-off speed of the yarn that is relatively low in relation to the fiber conveying speed in the channel, so that the subsequent part of a fiber is only partially is deflected like a whip, while the remaining part of this fiber is compressed in the gusset gap.

Another prior art is shown and described in the applicant's EP-A-0 175 862 [prior art under Art. 54 (3) EPC], in which
Fibers detached from a fiber structure and
by means of a pneumatic fiber conveying air flow guided in a conveying duct, free-flowing in a flight direction inclined at a predetermined acute angle to the mouth of the conveying duct and then transferred to a moving, perforated surface of the friction air spinning means for receiving the conveying air flow that is under vacuum,
from which the fibers are formed into a yarn in a so-called yarn formation point,
the yarn ultimately being drawn off in a predetermined direction (a; b),
whereby the conveying air flow is additionally accelerated in a predetermined area ending with the mouth by tapering this area, and in which the fibers are delivered neither in a perpendicular nor parallel to the yarn end, but in an intermediate position, in order to then at the yarn formation point in the End of twine turned in and pulled off as twine.

The disadvantage, however, is that with the device shown, the fibers assume the aforementioned expected position with an irregularity that is too great.

The invention is therefore based on the object of delivering the fibers to the friction spinning agent in a substantially stretched position without the risk of clogging and compression.

According to the invention, the object is achieved by the features contained in the first method claim and in the first device claim.

Further advantageous process steps respectively. Embodiments are listed in the further claims.

The invention is explained in more detail below with the aid of drawings which only show execution routes.

• Fig. 1 einen Längsschnitt durch eine erfindungsgemässe Vorrichtung, schematisch und teilweise im Schnitt dargestellt,
• Fig. 2 eine Draufsicht eines Teils der Vorrichtung von Fig. 1, entsprechend den Schnittlinien I-I,
• Fig. 3 eine Variante der Vorrichtung von Fig. 1,
• Fig. 4 eine Draufsicht der Vorrichtung von Fig. 3,
• Fig. 5 ein Detail der erfindungsgemässen Vorrichtung, im Schnitt gemäss den Linien II (Fig. 2), jedoch vergrössert dargestellt,
• Fig 6 eine Ansicht einer weiteren erfindungsgemässen Vorrichtung, halbschematisch dargestellt,
• Fig. 7 einen Teil der Vorrichtung von Fig. 6, mit Blickrichtung in Pfeilrichtung III (Fig. 6),
• Fig. 8 eine Draufsicht eines Teils der Vorrichtung von Fig. 6,
• Fig. 9 und 10 je einen Ausschnitt aus der Vorrichtung von Fig. 1 resp. 3 und Fig. 8, vergrössert und halbschematisch dargestellt.

Show it:

• 1 shows a longitudinal section through a device according to the invention, shown schematically and partly in section,
• 2 is a plan view of part of the device of FIG. 1, according to the section lines II,
• 3 shows a variant of the device of FIG. 1,
• 4 is a top view of the device of FIG. 3;
• 5 shows a detail of the device according to the invention, shown in section along lines II (FIG. 2), but enlarged,
• 6 shows a view of a further device according to the invention, shown semi-schematically,
• 7 shows part of the device of FIG. 6, looking in the direction of arrow III (FIG. 6),
• 8 is a top view of part of the device of FIG. 6;
• 9 and 10 each show a section of the device of Fig. 1 and. 3 and Fig. 8, shown enlarged and semi-schematic.

Fig. 1 shows a hint of an opening roller 1 known from the rotor open-end spinning process, which is mounted in a manner known per se in a housing 2 (only partially shown) and can be driven. The opening roller 1 is provided in a manner known per se (and therefore not described further) for opening a fiber sliver (not shown) into individual fibers 3, with needles 4 or teeth (not shown).

The housing 2 is connected to a fiber conveying channel 5 which opens close to the cylindrical surface of a perforated (see FIG. 5) friction spinning drum 6.

This friction spinning drum 6 has a suction channel 7 inside (FIG. 5), which delimits a suction zone R on the circumference of the friction spinning drum 6 through its walls 8 and 9. The walls 8 and 9 extend so close to the cylindrical inner wall 10 of the friction spinning drum 6 that, without touching the inner wall 10, an inflow of false air between the walls 8 and 9 and the inner wall 10 is practically prevented.

This air, which is sucked in by the suction channel 7 and also flows through the fiber conveying channel 5, causes the fibers 3 detached from the needles 4 and exposed in the conveying channel 5 within the aforementioned suction zone R at a surface area delimited by the outlet mouth 11 - also called the mouth 11 - of the conveying channel 5 Q of the rotating friction spinning drum 6, as described later, is held and ultimately turned into a yarn 12 at a yarn formation point 13.

This yarn formation point 13 is located in the region of an imaginary continuation of the wall 9 of the suction channel 7 through the cylindrical wall of the friction spinning drum 6, i.e. in the boundary area given by the wall 9 within the suction zone R.

The friction spinning drum 6 rotates in a direction indicated by the arrow U and thereby transports the fibers released in the surface area Q to the friction spinning drum 6 to the yarn formation point 13.

The finished yarn 12 is drawn off in a draw-off direction A by a pair of draw-off rollers 14.

The length (not shown) of the suction zone R, viewed in the direction of the yarn formation point 13, corresponds at least to the length L (FIG. 2) of the mouth 11. The length L and the clear width D.3 (FIGS. 2, 4 and 5) of the mouth 11 result in the mouth cross-section, whereby basically the mouth cross-section is to be understood as the outlet cross-section of the fiber conveying channel.

Fig. 1 further shows the fiber feed channel 5 with an inclination marked with an acute angle α. The angle of inclination α is formed by an imaginary extension of the mouth 11 and a lower wall 16 (as viewed in the direction seen in FIG. 1) of the channel 5. In addition, the mouth 11 is provided substantially parallel and at a predetermined distance a from the yarn formation point 13.

Provided that the opposite upper channel wall 17 is substantially parallel to the lower channel wall 16, the air flow in the channel also has an at least similar inclination to the mouth cross section.

Furthermore, FIG. 1 shows that the fiber conveyor channel in the mouth region has a strongly tapered part with the height M, which, as shown in FIGS. 2 and 5, tapers from the channel width D. 2 to the channel width D.3. The preceding part of the fiber conveyor channel 5 is also, but significantly less, tapered, which is shown with the channel width D.1 to width D.2 in FIG. 2.

In operation, the fibers detached from the needles 4 of the opening roller 1 from the sliver (not shown) are detected by the air flow Z, which will pass the needles later substantially and tangentially to the opening roller 1, and conveyed further as free-flying fibers 3 in the fiber feed channel 5. The air flow in the fiber feed channel is denoted by S.

This air flow S is accelerated in the tapered mouth region with the height M, corresponding to the change in cross-section, given by the change in the inside width of the fiber conveying channel 5 from D.2 to D.3, and is then taken up by the suction channel 7 through the perforated friction spinning drum 6.

In this acceleration zone, the air flow S is deflected towards the surface of the perforated friction spinning drum 6, as is indicated by the bow S.1 of the arrow S, so that the front part, viewed in the direction of flow, of a fiber 3 delivered in the direction of flow therein Acceleration zone also deflected according to the air flow S, then captured by the friction spinning drum, which is shown with the fiber layer 3.1, and is pulled off in the circumferential direction of the friction spinning drum 6. The rear part of this fiber is conveyed further in the air flow in the direction of arrow N (FIG. 1), in order to ultimately be released to the surface of the friction spinning drum 6 in a fiber layer marked 3.2. The size of the angle γ (FIG. 1) defining this latter fiber layer depends on the one hand on the ratio of the flow velocity of the air in front of the mouth region with the height M to the peripheral speed of the friction spinning drum 6, but on the other hand also on the height M itself, on the acceleration of the Air in the aforementioned mouth area, and from the angle of inclination α of the fiber feed channel. For example, the angle γ is smaller, as the angle α becomes smaller, provided that the stated ratio between air speed and peripheral speed of the friction spinning drum 6 is sufficiently large, the height M is adapted to the inclination of the fiber feed channel and the acceleration in the mentioned mouth area is sufficiently large to allow this to deflect said front end of the respective fiber sufficiently quickly against the friction spinning drum surface. Basically, when the angle α becomes smaller, the ratio between the air speed and the peripheral speed of the friction spinning drum has to be greater and the acceleration in the mouth region mentioned has to be increased as a result of the smaller selected height M.

It has been shown that the speed of the conveying air in the mouth is at least 50% higher than the speed at the beginning of the range mentioned, i.e. must be D.2 in order to achieve a sufficiently effective deflection of a front fiber end.

Furthermore, the tapered area in front of the mouth should not be higher than that the front end of a fiber covered by this area is a maximum of a third of the length of a medium fiber to be processed. The height M This taper should therefore be chosen between 5 and 15 millimeters.

Furthermore, it was found that the speed of the conveying air in the mouth 11 is not more than five times the speed in the channel width D.2, i.e. should be at the beginning of this area. Advantageously, the speed of the conveying air in the mouth 11 is between twice and four times the speed in the channel width D.2.

On the other hand, it is necessary that the speed of the air flow above the said tapered area is greater than the speed of movement of the friction spinning means in order to avoid that fibers essentially in the direction of movement of the friction spinning means, i.e. with a friction spinning drum in the circumferential direction and with a friction spinning disc in the direction of rotation.

It has also been shown that the speed of the conveying air flow above the tapered area with decreasing angle of inclination α of the fiber conveying channel 5, respectively. 5.1 must be larger in order to bring the fiber into the fiber layer 3.2 with the desired angle γ. For example, at an angle of inclination α of the fiber conveying channel between 30 and 10 degrees, the air speed mentioned should be between 15 m / sec. and 100 m / sec. be.

The angle of inclination γ of the fibers 3 in the fiber layer 3.2 is also reduced if the speed of the air flow mentioned above the tapered area increases while the speed of movement of the friction spinning means remains the same. At a minimum, the air flow mentioned must be twice as high as the speed of movement of the friction spin material.

The angle ε which characterizes the tapering of the area mentioned should be selected between 20 and 50 degrees, preferably between 30 and 40 degrees, in order to obtain the desired fiber deposition effect without excessive flow losses.

Furthermore, as shown in FIG. 9, the arrangement of the holes 52 resulting in the perforation of the surface of the friction spinning means - in this case, the friction spinning drum 6 - should be selected such that those connecting lines 50 or. 51 of the hole centers, which assume a position inclined at angles β.1 and β.2 to the yarn formation point 13, form an acute angle. The larger angle β.2 should not be greater than 80 and the small angle β.1 should not be less than 5 °. The small angle β.1 between 10 and 30 ° should preferably be chosen, since most fibers attach to these fiber orientation angles γ. Furthermore, the connecting lines 50, respectively. 51 compared to the delivery channel 5 respectively. 5.1 provided opposite to the yarn formation point 13 inclined.

Indeed, it has been found that the fibers tend to lie on the perforated friction spinning means along the rows of holes. This effect can be explained by the fact that the intensity of the air flow of each individual hole 52 is such that the air is able to force a fiber either on one or on the adjacent row of holes, so that fibers hardly touch the row of holes Friction spin agents come to rest. However, in order to actually get the fibers onto the friction spinning agent with the aforementioned methods in the fiber layer 3.2, the rows of holes in a layer corresponding to this fiber layer 3.2 have been chosen. In order to avoid that fibers are delivered to the yarn formation point 13 parallel to or even at a right angle thereto, the rows of holes are correspondingly arranged such that the straight lines (50, 51) connecting the hole centers are neither parallel to the yarn formation point 13 nor at a right angle are provided.

The friction spinning device of FIGS. 3 and 4 differs from that of FIGS. 1 and 2 essentially by the position of the opening roller 1 relative to the position of the mouth 11, and by the essentially parallel course of the channel widths D.1 and D.2 Channel walls 18 and 19 of the fiber feed channel 5.1. Accordingly, the elements having the same functions as those of the device of Figs. 1 and 2 are given the same reference numerals.

The fiber conveying channel 5.1 of the device in FIGS. 3 and 4 has in principle the same function as the fiber conveying channel 5 of the device in FIGS. 1 and 2, but with 5.1 since the walls 18 and 19 run essentially parallel.

In the device of FIGS. 1 and 2, the channel width D.1 corresponds to the width (not shown) of the opening roller 1, while the channel width D.1 of the fiber conveying channel 5.1 of the device of FIGS. 3 and 4 is selected independently of the width of the opening roller 1 can be, since in this variant the width mentioned gives the width T of the conveyor channel 5.1.

6-8 show the application of the invention in a friction spinning device as is known from the English patent specification No. 1 231 198 ago. 1 and 2 there is a friction spinning disc 30 and instead of a friction spinning drum 15, which rotates in a manner known per se as a counter-drum to the perforated drum 6 in the same direction of rotation, a conical counter-roller 31. The disc 30 is in perforated in a manner analogous to the drum 6 (only indicated in FIGS. 7 and 8) and rotates in the direction F by means of an associated shaft 33 in order to deliver the fibers 3 of the yarn formation point 13 (FIG. 8) delivered in the fiber conveying channel 5 or 5.1, in which they are twisted into yarn 12. The distance a.1 between the mouth 11 and the yarn formation point 13 corresponds to the mean distance.

The conical roller 31 rotates in the direction G. A suction channel 32, the suction opening of which is shown in broken lines in FIG. 8, has the same function as the previously mentioned suction channel 7.

The remaining elements with the same functions as those of the previous figures are provided with the same reference numerals. It is indicated in FIGS. 6 and 7 that the fiber feed channel can be provided either in the manner shown in FIGS. 1 and 2 or in the manner shown in FIGS. 3 and 4.

In a manner analogous to that described for FIG. 9 here, too, the holes 52 resulting in the perforation are arranged such that at least two of the straight lines connecting the rows of holes form an acute angle with the yarn formation point 13. These lines are marked with the reference numerals 53 and 54 and the associated angles with δ.1 resp. marked δ.2. It goes without saying that since it is a friction spinning disc and not a friction spinning drum, the hole arrangement must be provided in segments, as shown in FIG. 10.

In addition, with regard to the formation of the yarn in the yarn formation point 13 by means of the fibers in the fiber layer 3.2, reference is made to EP-A-0 175 862 (prior art according to Art. 54 (3) EPC).

The air flow Z mentioned earlier is guided in an air inlet duct 100 that runs tangentially to the opening roller 1. As shown in FIG. 1, this air inlet duct 100 opens straight into the fiber feed duct 5. However, it is also possible to provide this air inlet duct in a shape angled to the fiber feed duct 5; it is essential that this duct is designed such that the air flow Z in able to take over the fibers from the opening roller 1 and transfer them to the fiber feed channel.

The provision of the aforementioned air inlet duct 100 is not restricted to use in a device according to FIG. 1, but is possible in an analogous manner in all of the fiber conveying ducts shown.

The advantage of such an air inlet duct 100 and thus of an air flow Z is the possibility in a simple manner to obtain the amount of air necessary for the conveying speed of the fibers in the fiber conveying duct, and also that the air passing by the opening roller 1 can thus be provided at a speed. which is at least equal to or greater than the peripheral speed of the outermost diameter of the opening roller, so that the air flow Z exerts a stretching effect on the fibers to be taken over by the opening roller. As a result, there is the possibility that the fibers supplied to the acceleration zone in the mouth area have already undergone stretching, so that essentially stretched fibers can be added to the fiber layer 3.2.

Depending on the selected channel shape, e.g. one, as shown in Fig. 2, continuously tapered channel shape, the air flow S can experience a further acceleration between the opening roller and the acceleration area in the mouth, so that the fibers guided in the fiber feed channel at their front end, as seen in the conveying direction, also have a higher acceleration Experience the speed of the ambient air as its rear part, which also contributes to further stretching or at least to prevent curling of the fibers.

Furthermore, by simply selecting the amount of air (m³ / min), the air speed in the fiber feed channel can be selected in such a way that a desired dilution of the fiber flow in the fiber feed channel can be achieved, which is useful for the previously mentioned “rollover” of the fiber, since this Rollover effect becomes more effective with a decreasing number of fibers in the cross section of the fiber stream.

The amount of air is changed by changing the cross section of the air inlet channel 100 and / or by changing the negative pressure in the fiber feed channel 5. 5.1 changed.

Claims (10)

1. A method of spinning a yarn or the like in accordance with the open end friction spinning principle wherein

- fibres (3) are separated out of a fibre sliver (not shown) and

- are transported in free flight by means of a pneumatic fibre conveying airstream (S) guided in a conveying channel (5; 5.1) in a flight direction (N) inclined at a predetermined acute angle (α) to the mouth (11) of the conveying channel (5; 5.1), and are subsequently transferred to a moved apertured surface, through which the conveying airstream can pass, of a friction spinning device (6; 30) which is subjected to a depression to pick up the conveying airstream,

- by which the fibres are formed into a yarn in a so-called yarn formation position (13),

- with the yarn (12) finally being withdrawn in a predetermined direction (a),

   wherein the conveying airstream is additionally accelerated in a predetermined region which terminates at the mouth (11) and has a predetermined height (M), through tapering of this region, wherein the height (M) of this tapering region is selected between 5 mm and 15 mm but such that a maximum of a third of the length of an average fibre to be processed is acted on in the named region, and wherein
the conveying airstream is accelerated in the named region and deflected towards the mouth (11) in such a way that a front end part of a free flying fibre (3), as seen in the flight direction of the fibres, which is acted on in this region is deflected from the previously named flight direction (N) directed at a substantially acute angle (α) to the mouth into a position (3.1) which is more pronouncedly directed towards the mouth than the following remaining part of this fibre and is transmitted in this position through the mouth (11) onto the surface of the friction spinning device.

2. A method in accordance with claim 1, characterised in that the speed of the conveying airstream above the named region is larger than the speed of the surface of the friction spinning device so that the rear end part of the named fibre is transported further in this airstream in the direction (N) of the airstream (S) so that the fibre finally lies in a position (3.2) on the friction spinning means in which it is opposite inclined to the yarn formation position (13) in comparison to the conveying channel (5; 5.1) and includes an acute angle with the yarn formation position; and/or in
that as angle of inclination (α) of the flight direction becomes smaller, the height of the named region is smaller, and/or
in that the speed of the conveying air in the mouth (11) is at least 50% higher than the speed at the start (D.2) of the named region.

3. A method in accordance with claim 1 or claim 2, characterised in that the speed of the conveying air in the mouth (11) is increased at a maximum to five times the speed at the start (D.2) of the named region; in that the speed of the conveying air at the mouth (11) is preferably increased to two to four times the speed at the start (D.2) of the said region; and/or in that the speed of the said airstream is made larger as the angle of inclination (α) of the conveying channel (5; 5.1) becomes smaller, with the speed of the named said airstream expediently being selected to be larger while the speed of movement of the friction spinning means (6; 30) remains the same.

4. Method in accordance with one of the claims 1 to 3, characterised in that the speed of the said airflow is at least twice as large as the speed of movement of the friction spinning device (6; 30) and/or in that the angle of inclination (α) of the conveying channel (5; 5.1) lies between 30 and 10 degrees of angle at a speed of the said airstream between 50 m/sec. and 100 m/sec.; and/or in that the conveying airstream has a speed which is at least the same as or larger than the speed of the fibres themselves for stretching the fibres (3) on picking up the separated out fibres (3).

5. Apparatus for carrying out the method in accordance with one of the preceding claims

- comprising a means for separating out fibres (3) from a fibre sliver, and

- a fibre conveying channel (5; 5.1), the mouth (11) of which is provided substantially parallel to and at a predetermined spacing (a; a.1) from a yarn formation position (13) and from a friction spinning device in order to pneumatically convey these fibres onto the perforated surface of the friction spinning device (6; 30), on which these fibres are then formed at the yarn formation position (13) into a yarn (12) which

- is drawn by a yarn drawing means (14),

wherein the fibre conveying channel (5; 5.1) has a region directly before the outlet mouth (11) with a height (M) measured perpendicular to the mouth (11) within which the fibre conveying channel (5; 5.1) has a more pronounced taper having a predetermined angle (ε), than before this region, wherein the height (M) of the taper lies between 5 and 15 mm and wherein the conveying channel is inclined at a predetermined acute angle (α) to its mouth (11).

6. Apparatus in accordance with claim 5, characterised in that the angle (ε) of the taper is selectable between 20 to 50 degrees of angle; with the height (M) and the angle (ε) of the taper preferably being such that the speed of the conveying air at the mouth (11) is at least 50% higher than before the same region.

7. Apparatus in accordance with claim 5 or claim 6, characterised in that the taper is such that the speed of the conveying air in the mouth (11) is increased to a maximum of five times the speed at the start of the said region; and/or in that the height (M) of the taper is changed in dependence on the angle of inclination (α) of the conveying channel (5; 5.1) and/or in that the angle (ε) of the taper is changed in dependence on the angle of inclination (α) of the conveying channel (5; 5.1), with the height (M) of the taper expediently becoming smaller as the angle of inclination (α) becomes smaller, as a function of the angle of inclination.

8. Apparatus in accordance with one of the claims 5 to 7, characterised in that the angle (ε) of the taper becomes larger as the angle of inclination (α) becomes smaller as a function of the angle of inclination, and/or in that the arrangement of the holes (52) forming the said perforation is such that the straight lines (50, 51; 53, 54) connecting the hole centres, which are oppositely inclined to the yarn formation position (13) in comparison to the conveying channel (5; 5.1), include an acute angle (β.1, β.2; δ.1, δ.2) with the yarn formation position (13), with the straight lines (50, 51; 53, 54) connecting the hole centres expediently including angles of two different sizes (β.1, β.2; δ.1, δ.2) within the range of the acute angle.

9. Apparatus in accordance with claim 8, characterised in that one of the angles (β.2; δ.2) is a maximum of 80°, and/or in that one of the angles (β.1, δ.1) has a minimum of 5°, and/or in that one of the angles (β.1; δ.1) is smaller than 30° but larger than 10°.

10. Apparatus in accordance with one of the claims 5 to 9, characterised in that the means for separating fibres out of the fibre sliver is an opening roll (1); and in that the fibre conveying duct (5; 5.1) has an air inlet duct (100) extending substantially tangential to the opening roller (1) and opening into the fibre conveying duct (5; 5.1), with the air inlet duct (100) preferably opening in a straight line into the fibre conveying duct (5; 5.1).

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