JP2007522355A - Certain bonding materials in air jet spinning. - Google Patents

Abstract

  The present invention relates to a method for starting a draft mechanism (1) for drawing a fiber bundle (2). For this purpose, the draft mechanism (1) comprises at least one front roller pair (3) and a rear roller pair (4) having a nip line (5), in which case the draft mechanism (1) A fiber bundle end (6) is provided for starting. According to the present invention, at the start of the draft mechanism (1), the approach process from the acceleration is completed in the course of the rotational speed of the front roller pair (3) and the course of the rotational speed of the rear roller pair (4), For the first time, the fiber bundle end (6) enters the nip line (5) of the rear roller pair (4).

Description

  The invention relates to a method for starting a drafting mechanism of the type described in the superordinate concept of claims 1 and 3, a control device for a drafting mechanism of a textile machine of the type described in the superordinate concept of claim 11, And a textile machine with a control device of the type defined in claim 12.

BACKGROUND OF THE INVENTION Methods for starting a draft mechanism are known in the fiber art. Such methods are described in European Patent No. 1219737, European Patent No. 807700 and European Patent No. 1375709. As can be seen from the above specification, the present invention is particularly suitable for starting a draft mechanism belonging to an air jet spinning machine. In an air jet spinning machine, fiber bundles are spun by one or more air streams to form yarns.

  However, there are drawbacks with the known methods of starting the draft mechanism. This is especially true for draft mechanisms belonging to air jet spinning machines, or draft mechanisms that guide drawn fibers into a spinning unit that operates according to the air jet spinning method. Due to the disadvantages of the known methods of starting the drafting mechanism, the quality of the joint is not always satisfactory. A joint is understood as a “Nahtstelle” inside the yarn, where the yarn is joined again or connected, for example after production interruption. Generally, a joint is formed by spinning another fiber at or around an existing yarn end. The joint forms the actual overlap area between the yarn end and additionally the new fibers spun on it. In many cases, the joints form thick spots that are not actually desired. Ideally, the joint or joint should not be different from the rest of the yarn, especially with respect to strength and fiber mass. In order to obtain an ideal state, various ideas are disclosed in the above-mentioned literature. For example, the fiber ends to be joined are tapered and / or the drafting mechanism conveys fewer fibers in the overlap region than in the subsequent steady state operation. Despite this, the known apparatus still presents other problems that are overcome by the present invention.

  It was recognized that when the draft mechanism was started, and in turn, when the associated roller pair started or accelerated, a vibration process of the number of rotations to the joining speed occurred. When the rotation speed is first reached by the vibration process (vertical vibration) caused by accelerating the roller pair from the stop state to an appropriate bonding speed or rotation speed (see FIG. 2 and the description of the embodiment described later). This results in a non-constant rotational speed of the roller pair, which in turn results in a non-constant rotational speed characteristic between the draft mechanism roller pair. In a normal drafting mechanism, the joining process begins while the roller pair is accelerated to the operating speed or immediately after the prescribed joining speed is reached. In other words, the vibration process of the roller pair at the time of acceleration to the joining speed has not been considered at all in forming the joining portion. Thus, conventional joints have occurred with a non-constant rotational speed or a non-constant rotational characteristic of the draft mechanism between both pairs of rollers that exert stretching. Therefore, the vertical vibration of the roller pair causes inaccurate and uneven stretching of the fiber bundle. When the fiber bundles that have been stretched in a dispersed manner are combined with the yarn end portion, a joined portion is formed thereby, but the joined portion also has a mass variation. As a result, in the overlapping region of the joint, in many cases, an unacceptable thick spot is formed following an unacceptable thin spot. In the opposite case, a thin spot occurs in the overlapping region or the joining fails completely.

  The object of the present invention is therefore to improve the method for starting a drafting mechanism for drawing fiber bundles of the type mentioned at the outset so that mass fluctuations in the joint are reduced or minimized. Is to provide something. A still further problem is to provide a method for starting the drafting mechanism such that the fiber bundle is drawn with the correct drawing characteristics from the beginning.

  This problem is solved by the method described in the characterizing part of claims 1 and 3.

  The advantageous operation of the method according to the invention is explained below with reference to FIGS.

  FIG. 1 shows a typical draft mechanism 1 in which the method according to the invention is recognized. The draft mechanism 1 includes a front (upstream) roller pair 3 and a rear (downstream) roller pair 4 having a nip line 5. The draft mechanism 1 may further include another roller pair 7. The draft mechanism 1 is useful for drawing (drafting) the fiber bundle 2. Therefore, the roller pairs 3 and 4 rotate at different speeds or peripheral speeds. Accordingly, the front roller pair 3 and the rear roller pair 4 form a so-called main stretching area 8 of the draft mechanism 1. Stretching can also be performed between the roller pair 7 and the roller pair 3 (so-called preliminary stretching). In general, the draft mechanism includes an apron 20 in the front roller pair 3 as shown in FIG. 1, and the apron 20 serves to guide the fiber bundle 2 to be drawn. The apron 20 is not critical to the present invention and need not be provided. In steady operation, the fiber bundle 2 runs through roller pairs 7 (if provided) and in particular through roller pairs 3 and 4. In this case, the fiber bundle 2 is drawn and separated from the draft mechanism 1 at the nip line 5 of the rear roller pair 4 or at the downstream side of the nip line 5. The drawn fiber bundle is then often processed in the same manner (for example in a spinning unit, see FIG. 4 for this). If for some reason production is interrupted or it is generally necessary to run the drafting mechanism 1 again, the fiber bundle 2 must be reintroduced into the drafting mechanism 1 or at least correctly positioned. Therefore, the position of the fiber bundle end portion 6 plays a particularly important role. It is not important here for the present invention whether the draft mechanism 1 comprises an additional roller pair 7 or a further roller pair. When the production is interrupted, the roller pairs of the draft mechanism 1 are sequentially stopped, so that the fiber bundle 2 is cut at the nip line 5. For this reason, the front roller pair 3 is stopped earlier than the rear roller pair 4. As a result, the fiber bundle end 6 is positioned immediately before the nip line 5. In this connection, reference is made, for example, to EP 1375709 cited above.

  When the draft mechanism 1 is operated again, in principle, the rear roller pair 4 first starts rotating before the front roller pair 3 is operated again. Therefore, the time interval between the start of the rear roller pair 4 and the start of the front roller pair 3 is sufficient, and the rotation speed of the roller pair 4 elapses before the front roller pair 3 is operated. This completes the vibration process from acceleration. Since the fiber bundle end 6 exists immediately before the nip line 5 of the rear roller pair 4, the fiber bundle 2 is stretched immediately after the front roller pair 3 is started. Since the front roller pair 3 needs to be further accelerated to the joining speed or the operating speed after starting, vibration to the desired joining rotational speed occurs again here. As a result, in the region of the fiber bundle 2 that immediately follows the fiber bundle end portion 6, a variable stretching is performed, and therefore there is an undesirable mass variation in this region. If the “starting end region” of the fiber bundle 2 is used to form the joint, it will be understood that the joint will have an undesirable mass variation.

The occurrence of such mass fluctuation can be seen well from FIG. FIG 2, particularly shown and rotational speed course U ₃ speed course of the rear roller pair ₄ U 4 _(t) and ahead of the roller pair 3 _(t). The rear roller pair 4 is started at time t = 0. In this regard, the roller pair 4 described above is accelerated during the time interval t _{h, 4} until the roller pair 4 reaches the joining rotational speed U _{A, 4} (eg ˜5 mm / msec). The acceleration of the roller is extremely large. This is because the thread end 10 must be selected longer than the allowable range otherwise. Therefore, acceleration (Hochfahren) takes place within a few milliseconds. For physical reasons, it is impossible for the roller pair to suddenly interrupt acceleration when the desired number of revolutions is reached in the case of a constant but very high acceleration, so that vibrations _occur during a specific time interval t _EV4 . A process occurs. The same applies to the front roller pair 3 (oscillating process during time interval t _EV3 ). How long the vibration process lasts and how large the vertical vibration is depends on the physical characteristics of the driven roller pair and on the driving device, adjusting device and control device. By using an appropriate adjustment device and drive, the time interval t _EV can be minimized. However, this cannot be completely avoided due to the high acceleration of the roller pair.

In order to prevent mass fluctuation due to the above-described action from occurring in the start end region of the fiber bundle drawn at the start of the draft mechanism, according to the present invention, both ends of the fiber bundle (in short, the tip portion of the fiber bundle) The first roller pair is supplied to the nip line of the second roller pair only after completing the appropriate vibration process from the acceleration. This time point is shown as t _EVE in FIG. At this point, both roller pairs reach a certain number of joint rotations (as shown) or at least finish the vibration process. According to the present invention, the drawing of the fiber bundle at the time t _EVE at the earliest resumption, also in other words, both at time t _EVE earlier, fiber bundle end portion enters the nip line of the second pair of rollers, thus It may be stretched. Since the start of the drafting mechanism involves a joining process with the yarn end as well as a harmonized drawing, the starting point of the joining process t _K must not be before the time t _EVE . Time t _EVE is therefore the earliest time to start the joining process. Once the joining process has taken place, the joining process lasts a few milliseconds (see time interval t _AE , eg ˜8 msec) and is terminated at time t _E. Following the joining process at time t _E , the draft mechanism can again be in steady operation. Advantageously, the joining process takes place at a constant joining speed U _{A, 4} or joining speed U _{A, 3} , in which case both pairs of rollers are synchronously and slowly after joining. Without any upward vibration, it is possible to accelerate to the operating rotational speed UB _{, 3} and the operating rotational speed UB _{, 4} . Therefore, it is conceivable that the joining is performed at substantially the operating speed, so that the joining speed U _{A, 3} and the joining speed U _{A, 4} already constitute the operating speed for the steady operation of the draft mechanism. The synchronous acceleration of the roller to an operating rotational speed different from the joining rotational speed is indicated by a chain line in FIG.

  With regard to the method according to the invention, there are various advantageous embodiments found in the dependent claims.

  The present invention will be described below with respect to the idea or mode of operation of the present invention based on another drawing. Note that the present invention or the idea of the present invention is not limited to the illustrated embodiment.

  FIG. 3 shows a draft mechanism in which the joining process is performed. Here, the method according to the invention is used to start the drafting mechanism. In order to perform the joining process, the existing yarn end 10 is first pulled through the spinning unit 12 in the direction opposite to the actual spinning direction. The spinning unit 12 is arranged downstream of the draft mechanism. The yarn end 10 is likewise guided through the nip line 5 of the rear roller pair 4, cut to a defined length, and properly positioned for starting. When starting the draft mechanism, the rear roller pair 4 is first rotated as shown in FIG. Next, the front roller pair 3 is operated. It is also conceivable to operate both roller pairs simultaneously (corresponding to an embodiment possible with the method according to the invention). Prior to starting the drafting mechanism, the fiber bundle end 6 is arranged at a specified interval with respect to the nip line 5 of the rear roller pair 4 as shown in the figure. This interval is such that when at least the fiber bundle end portion 6 reaches the nip line 5, both the roller pairs 3 and 4 end the vibration process from the acceleration after the number of rotations. As described above, when joining is performed, a part of the yarn end portion 10 and a part of the front region of the illustrated fiber bundle 2 overlap each other. This overlapping region is spun by the subsequent spinning unit 12 to form an actual joint.

  FIG. 4 shows the draft mechanism operated by the method of the present invention and the subsequent spinning unit 12. In the drawing, the draft mechanism 1 and the spinning unit 12 are shown in a steady operation state. Individual structural members corresponding to the structural members shown in FIGS. 1 to 3 are denoted by the same reference numerals. The rollers 16 of the rear roller pair 4 convey the pre-stretched fiber bundle 11 to the spinning unit 12. The spinning unit 12 can advantageously spin the fiber bundle 11 according to various spinning methods. The drawing shows a spinning unit 12 operating according to an air jet spinning method (so-called vortex-air jet spinning method). For this purpose, the spinning unit 12 includes a vortex chamber 14 and a spindle 15 provided in the vortex chamber 14. Strictly speaking, the spindle 15 is a spinning nozzle that does not rotate advantageously. In the vortex chamber 14, an air vortex is formed by a nozzle, and the air vortex brings about spinning of the fibers of the pre-spun fiber bundle 11 in the opening of the spindle 15. The yarn 13 thus produced is appropriately stretched and wound on a winding device (not shown). As can be seen from the drawing, the draft mechanism 1 is additionally provided with a roller pair 7, which together with the roller pair 3 forms a pre-stretching zone 9. To reiterate, the method of starting the drafting mechanism according to the invention is not limited to a specific spinning method, such as the air jet spinning method shown here, but limited to the use of another roller pair 7. It is not what is done.

  FIG. 5 shows a control device 19 according to the present invention. The control device 19 operates the draft mechanism 1 on the basis of the method according to the invention. For this purpose, the rear roller pair 4 is provided with its own drive device 18, and similarly the front drive device 3 is provided with its own drive device 17. As shown in the drawing, the draft mechanism 1 further includes another roller pair 7, and the roller pair 7 forms a preliminary spinning area together with the roller pair 3. Can also be driven (or provided with an additional unique drive). The control device 19 according to the invention controls the drive devices 17 and 18 when starting the draft mechanism according to the method according to the invention. The control device 19 can be connected to other suitable monitoring and control devices of the textile machine (the textile machine as a whole is not shown).

  It is also included in the present invention that the fiber bundle end 6 is moved backward from the nip line 5 of the rear roller pair 4 before starting the draft mechanism depending on how the draft mechanism has been stopped in advance. And This can also be done automatically using the control device 19 and the drive device 17, for example. This is especially true when the fiber bundle end 6 is not manually separated from the nip line 5 of the rear roller pair 4 at a set distance. This is particularly desirable in fully automatic joining methods and equipment, where the drafting mechanism 1 is pre-stopped so that the fiber bundle 2 is separated at the nip line 5 of the rear roller pair 4. In short, in this case, a clearly defined fiber bundle end 6 is produced before the draft mechanism can be operated again, and the fiber bundle end 6 need only be positioned appropriately.

  The present invention is not limited to the described embodiments and ideas. Rather, such a method is regarded by those skilled in the art as changing the idea according to the invention in the most advantageous manner possible. Accordingly, other advantageous specifications and combinations can be easily derived from the described embodiments, which likewise constitute the idea of the invention and are protected by the present description. Several disclosed features are set forth in a combined form in the specification and are also combined in the claims. Thus, individual features in the specification may be claimed individually or in other combinations within the spirit of the invention. Thereby, the applicant reserves another combination using the idea of the present invention.

FIG. 2 is a schematic diagram showing a typical draft mechanism. It is a diagram which shows mass fluctuation | variation. It is the schematic which shows a draft mechanism. It is the schematic which shows a draft mechanism. It is the schematic which shows a draft mechanism.

Explanation of symbols

1 Draft mechanism,
2 fiber bundles,
3 Front roller pair,
4 Back roller pair,
5 Nipline,
6 Fiber bundle end,
7 Roller pair,
8 Main stretch area,
9 Pre-drawing zone,
10 Yarn end,
11 drawn fiber bundles,
12 spinning units,
13 Yarn,
14 vortex chamber,
15 spindle,
16 Rollers in the rear roller pair,
17 Drive device for pre-stretching zone,
18 Driving device for rear roller pair,
19 control device,
20 apron,
The number of rotations of the roller pair 4 at the back of U _{4 (t)} ,
The number of revolutions of the roller pair 3 in front of U _{3 (t)}
U _{A, 4} Joining rotational speed for the rear roller pair 4,
U _{A, 3} Joining rotational speed for the roller pair 4 in front,
t _{s, 3} time point for starting roller pair ₃ ahead,
time interval (acceleration) until the roller pair _{3 in} front of t _{h, 3} reaches the joining rotational speed UA, 3,
t _{h, 4} Time interval (acceleration) until the rear roller pair 4 reaches the joining rotational speed UA, 4,
time interval until the pair of rollers ₃ ahead of t _{E, V3} finishes the vibration process from acceleration,
time interval until the pair of rollers ₄ behind t _{E, V4} finishes the vibration process from acceleration,
t _K Joining process start time,
at the end of the t _E joining process,
t _AE joining process time interval,
t _{EVE When} both roller pairs finish the vibration process,
U _{B, 4} The operating rotational speed of the roller pair 4 at the rear,
Operation speed of roller pair 3 in front of UB _{, 3}

Claims (13)

A method of starting a draft mechanism (1) for drawing a fiber bundle (2),
The draft mechanism (1) comprises a front roller pair (3) and a rear roller pair (4) having a nip line (5), and the fiber bundle end to start the draft mechanism (1) In the method of providing (6),
Before starting the drafting mechanism (1), the fiber bundle end (6) is positioned at a set distance relative to the nip line (5) of the rear roller pair (4), preferably The spacing is up to 6 mm, more preferably the spacing is from 0.1 mm to 5 m, particularly preferably the spacing is 3 mm or 4 mm, and the positioning of the spacing is preferably performed by cutting the fiber bundle end (6) A method for starting a draft mechanism, characterized by: A method of starting a draft mechanism (1) for drawing a fiber bundle (2),
The draft mechanism (1) comprises a front roller pair (3) and a rear roller pair (4) having a nip line (5), and the fiber bundle end to start the draft mechanism (1) In the method of providing (6),
At the start of the draft mechanism (1), the fiber bundle end (6) is not reached until the vibration process from the acceleration is completed in the course of the rotational speed of the front roller pair (3) and the course of the rotational speed of the rear roller pair (4). ) Enters the nip line (5) of the rear roller pair (4),
The front roller pair (3) and the rear roller pair (4) preferably have a constant rotational value when the fiber bundle end (6) enters the nip line (5) of the rear roller pair (4). A method for starting a draft mechanism, comprising:   Before starting the drafting mechanism (1), the fiber bundle end (6) is positioned at a set distance relative to the nip line (5) of the rear roller pair (4), preferably The method according to claim 2, wherein the distance is from 0.1 mm to 5 m, more preferably the distance is 3 mm or 4 mm. A method of starting a draft mechanism (1) for drawing a fiber bundle (2),
The draft mechanism (1) comprises a front roller pair (3) and a rear roller pair (4) having a nip line (5), and the fiber bundle end to start the draft mechanism (1) In the method of providing (6),
Before starting the drafting mechanism (1), the fiber bundle end (6) is positioned at a set distance relative to the nip line (5) of the rear roller pair (4), preferably The spacing is up to 6 mm, more preferably the spacing is from 0.1 mm to 5 m, particularly preferably the spacing is 3 mm or 4 mm, and the positioning of the spacing is preferably performed by cutting the fiber bundle end (6) A method for starting a draft mechanism, characterized by:   The draft mechanism (1) is provided with another at least one roller pair (7), the front roller pair (3) and the rear roller pair (4) are preferably the main extension of the draft mechanism (1). 5. The method as claimed in claim 1, wherein the region (8) is formed.   6. The method as claimed in claim 1, wherein the rear roller pair (4) forms an exit roller pair of the draft mechanism (1).   After or at the start of the drafting mechanism (1), a part of the drawn fiber bundle (2) is superposed on the yarn end (10), and for this purpose the yarn end (10) is also similar. 7. The method as claimed in claim 1, wherein the nip line (5) of the rear roller pair (4) is passed through.   The draft mechanism (1) conveys the drawn fiber bundle (11) directly to the spinning unit (12), and the spinning unit (12) spins the fiber bundle (2, 11) to obtain the yarn ( 13), preferably the drafting mechanism (1) and the spinning unit (12) form a component of the spinning section of the textile machine. The method described.   Using an air jet spinning method, the spinning unit (12) spins the fiber bundles (2, 11) to form the yarn (13), and advantageously the spinning unit (12) comprises a vortex chamber (14). ) And a spindle (15).   When the fiber bundle end (6) enters the nip line (5) of the rear roller pair (4), the roller (16) of the rear roller pair (4) has a speed of at least 300 m / min. Or the fiber bundle (11) has a speed of at least 300 m / min immediately after separating the nip line (5) of the rear roller pair (4). The method according to claim 1.   The fiber bundle end portion enters the nip line (5) of the rear roller pair (4) at a roller rotation value lower than the operation rotation value, and the nip line (5 of the rear roller pair (4) is obtained. 11. The method according to claim 1, further comprising the step of accelerating the rollers (3, 4, 16) synchronously with the operating speed following the entry of the fiber bundle (6) into . In a control device for one or more draft mechanisms (1) of a textile machine,
12. A textile machine singular, characterized in that the control device (19) is adapted to carry out the method according to any one of claims 1 to 11 in order to start one or more draft mechanisms. Or a controller for multiple draft mechanisms.   A textile machine comprising one or more control devices (1) according to claim 12.

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