EP1564317A1 - Method for obtaining a pieced yarn lenght having constant mass in a vortex Spinning procedure - Google Patents

Abstract

In a start-up process for a textile drafting machine the fiber ends are fed to a front pair of drums (3) and then to a rear pair of drums (5). The fiber ends are first inserted in the rear drum nip zone when both sets of drums are in a steady state and no longer accelerating. Process to start up textile drafting station for air vortex spinning assembly. Prior to insertion of the feed, the fibers are heald at readiness at a distance of 3-4 mm from the nip.

Description

The present invention relates to a method for starting up a drafting system according to the preamble of the independent claim 1 and 3, as well as a Control for drafting systems of a textile machine according to the preamble of the claim 11, and a textile machine with a said controller according to claim 12th

State of the art

Methods for the commissioning of drafting systems are known in the textile industry. The Documents EP 121 97 37, EP 807 700, and EP 137 57 09 describe such methods. However, the present invention is particularly suitable, as from the mentioned It can be seen, for the commissioning of drafting, which to Air spinning machines include. In air-jet spinning a fiber structure by means of spun one or more air streams into a yarn.

However, the known methods for commissioning a drafting system have Disadvantages. This is especially true for drafting, which to air spinning machines belong to drafting equipment, the warped fiber structure to a spinning unit forward, which work after an air spinning process. A disadvantage of the known Method of commissioning a drafting system is that the piecing quality is not always satisfactory. The piecing means an "interface" within a yarn, on which the yarn, for example, after a production interruption "scheduled" or "appended" again. Usually, a piecing produced by further fibers on or around an existing yarn end be spun. The piecing represents an actual overlap area between a yarn end and in addition to it spun new fibers. often he thus represents a thick spot, which is actually undesirable. Ideally should a piecing or piecing point not differ from the rest of the yarn, this applies in particular with regard to strength and fiber mass. In an effort to To achieve this ideal state, different in the above-mentioned writings Possibilities revealed. For example, the fiber end to which is to be recognized, tapered and / or the drafting provides in the overlap area less fibers than in the subsequent stationary operating state. Regardless, there is still another in the known devices Problem which the present invention intends to solve.

It has been found that when commissioning a drafting and thus during commissioning or when accelerating the associated roller pairs Transient response of the speed curve to the corresponding attachment speeds takes place. This transient process (overshoots and undershoots), which by raising the pairs of rollers from standstill to the corresponding Ansetzgeschwindigkeit or -drehzahl is caused (see Fig. 2 and later description), causes a non-constant at the first reaching the Ansetzdrehzahl Speed curve of the roller pairs and thus a non-constant speed ratio between the roller pairs of a drafting system. Usually starts the piecing process in a drafting system during the acceleration of the roller pairs to an operating speed or immediately after reaching a fixed Ramming. In other words, when making a piecing the transient process of the pairs of rollers during their acceleration on the Ansetzgeschwindigkeit never considered. This created so far a piecing at non-constant speeds or a non-constant speed ratio between the two pairs of rollers of a drafting system, which cause the delay. Due to the over- and undershoot of the pairs of rollers namely creates a inaccurate or varying distortion in the fiber structure. Is this varying warped Fiber composite merged with a yarn end, creating a piecing arises, so this piecing on mass fluctuations. As a consequence, that in the overlap region of the piecing usually an inadmissible thick spot arises, often followed by an impermissible thin spot. In the opposite case arises a thin spot in the overlap area or the attachment fails completely.

The present invention is therefore based on the object, a method for commissioning a drafting system for warping a fiber strand to provide, with which mass fluctuations in piecing be avoided or minimized. When Task can also be viewed, a method of commissioning a Draw frame to create, in which a fiber structure from the beginning with the correct distortion ratio should be distorted.

This task or tasks are characterized by the features in the independent Claims 1 and 3 solved.

The advantageous effect of the method according to the invention will now be described below explained with reference to Figures 1 and 2.

FIG. 1 shows a typical drafting arrangement 1, on which the invention Procedure can be applied. The drafting system 1 has for this purpose a front pair of rollers 3 and a rear, a nip 5 exhibiting pair of rollers 4. The Drawframe 1 may have another pair of rollers 7. The drafting 1 is used for Warping of the fiber structure 2. For this purpose, the roller pairs 3 and 4 rotate with different Speeds or peripheral speeds. The front pair of rollers 3 and the rear roller pair 4 thus form the so-called main drafting zone 8 of the drafting 1. Between the pairs of rollers 7 and 3 can also be a delay take place (so-called pre-delay). As a rule, a drafting system, as in 1, at the front roller pair 3 straps 20, which of the Guiding the distorted fiber structure 2 serve. The presence of the However, apron 20 is not essential to the invention or is not absolutely necessary. in the Stationary operation, fiber structure 2 passes through roller pair 7 (if present) and especially the roller pairs 3 and 4. Here, the fiber structure 2 is warped and leaves the drafting system 1 at or after the nip line 5 of the rear roller pair 4. The warped fiber structure is usually processed immediately afterwards (e.g., on a spinning unit, see the following Figure 4). Find out now any reasons a production interruption instead or must the drafting 1 Generally be put back into operation, so the fiber strand 2 again be inserted into the drafting 1 or at least correctly positioned. The position the fiber end-dressing 6 therefore plays a particularly important role. For the Invention, it is immaterial whether the drafting system 1 while the additional pair of rollers 7 or even another pair of rollers. Usually it is like that a production interruption, the pairs of rollers of the drafting 1 in an order be turned off that the fiber structure 2 demolished at the nip line 5 becomes. For this purpose, the front roller pair 3 is parked in front of the rear roller pair 4. As a result, the fiber composite end 6 is located immediately in front of the nip line 5. See, for example, the aforementioned EP 137 57 09.

If the drafting system 1 is now put back into operation, usually begins first to rotate the rear roller pair 4, before the front roller pair 3 in turn resumes operation. It may well be that the period between the Commissioning of the rear roller pair 4 and the front roller pair. 3 is large enough, so in the speed curve of the roller pair 4 of the transient process from the acceleration is completed before the front roller pair 3 in motion is set. Since the sliver end 6 but immediately before the nip line 5 of the rear roller pair 4 is found a delay of the fiber structure. 2 immediately after commissioning of the front roller pair 3 instead. Because the front Roller pair 3 after its start up still on the Ansetzgeschwindigkeit or Must accelerate operating speed, also finds a settling on here the desired Ansetzdrehzahl instead. This will be the immediate end of the sliver 6, the following area of the fiber structure 2 warped and thus points unwanted mass fluctuations. Will this "starting area" of the fiber structure 2 used to produce a piecing, so naturally also this piecing unwanted mass fluctuations.

That these mass fluctuations arise can also be very well seen in the figure 2. The figure shows, inter alia, the speed curve U ₄ (t) of the rear roller pair 4 and the speed curve U ₃ (t) of the front roller pair 3. At a time t = 0, the rear roller pair 4 is put into operation. For this purpose, said roller pair 4 accelerates during a period t _{h, 4} until the roller pair 4 has reached the attachment speed U _{A, 4} (eg ~ 5 mm / msec). The acceleration of the rollers is very high because the yarn end 10 otherwise has to be chosen unbearably long. Booting therefore occurs for a few milliseconds. For physical reasons, it is not possible for the roller pairs to abruptly abort the acceleration at the constant, but very high accelerations when the desired speed is reached, so that a transient occurs during a certain period t _{EV, 4} . The same applies mutatis mutandis to the front pair of rollers 3 (transient action during the period t _{EV, 3} ). How long this transient process lasts and how great the overshoot or undershoot depends on the physical properties of the driven roller pairs, as well as their drive, control, and control. By using suitable controls and drives, the period t _EV can be reduced to a minimum. Due to the high accelerations of the roller pairs but not completely prevent.

So that no mass fluctuations occur during the commissioning of a drafting system by the mentioned effects in the initial region of the warped fiber structure, according to the invention, the fiber composite end (ie the foremost tip of the fiber structure) is then fed to the nip line of the second pair of rolls if both pairs of rolls undergo their corresponding transient processes from the acceleration have finished. This point in time is designated in FIG. 2 by t _EVE : at this time both roller pairs have reached a constant attachment speed (as shown in the figure) or they have at least ended the transient process. According to the invention will now be at the earliest at the time t _EVE with the distortion of the fiber sliver re-started or in other words, at the earliest at the time t _EVE can the fiber strand end into the nip of the second rear roller pair enter and be moved with it. If the start-up of the drafting system, in addition to this coordinated delay, also includes a piecing operation with a yarn end, the time for the start of the piecing process t _{K must} not be prior to the time t _EVE . The time t _EVE is thus the earliest time to start the piecing process. If a piecing process is performed, it takes a few milliseconds (see period t _AE , eg -8 msec) and is completed at a time t _E. With the completion of the piecing process at time t _E , the drafting is again stationary operated. Preferably, the piecing takes place at a constant Ansetzdrehzahl U _{A, 4} or U _{A, 3} , wherein after completion of both pairs of rolls synchronously and slowly, ie without overshoot, can ramp up to their respective operating speed U _{B, 3} and U _{B, 4} . But it is quite conceivable that the quasi-quotaing takes place at operating speed, so that the Ansetzdrehzahlen U _{A, 3} and U _{A, 4} already represent the operating figures for the stationary operation of the drafting system. The synchronous raising of the rollers to a different starting speed of the Ansetzdrehzahl operating speed is shown in dashed lines in Figure 2.

There are various advantageous embodiments for the method according to the invention and embodiments which can be found in the dependent claims are.

In the following, the invention and the inventive concept or their mode of action explained with reference to other figures. It should be pointed out be that the invention or the inventive concept is not on the in the figures and examples shown.

FIG. 3 shows a drafting system on which a piecing process is to be carried out. while doing the commissioning process according to the invention application place. To carry out the piecing process, an existing yarn end is first 10 pulled against the actual spinning direction by the spinning unit 12, which is arranged after the drafting system. The yarn end 10 is also through the Clamping line 5 of the rear roller pair 4 out and - to a certain length cut to length - positioned accordingly for commissioning. When commissioning the Drawframe begins as shown in Figure 2, first the rear roller pair 4th to rotate. Only then is the front pair of rollers 3 put into operation. It is also possible that both pairs of rollers are put into operation simultaneously (corresponds to a possible variant of the inventive method). Before commissioning However, the drafting is the sliver end 6 as shown in FIG brought a certain distance to the nip line 5 of the rear roller pair 4. This distance is at least so great that when the sliver end 6 the Clamping line 5 reached, both pairs of rollers 3 and 4 in the speed curve the transient process have finished from the acceleration. Will be described as above set, so overlap a part of the yarn end 10 and the front Area of the illustrated fiber structure 2. This overlap area is spun in the subsequent spinning unit 12 to the actual piecing.

FIG. 4 shows a drafting arrangement which is provided with the method according to the invention in FIG Operation was taken and their subsequent spinning unit 12. The figure shows the drafting system 1 and the spinning unit 12 in stationary operating condition. The single ones Elements correspond to the preceding figures and are correspondingly provided the same reference numerals. The rollers 16 of the rear roller pair 4 deliver the warped fiber structure 11 of the spinning unit 12. The spinning unit 12 can Spinning the warped fiber structure 11 by various spinning processes. In This figure shows a spinning unit 12, which after an air spinning process works (so-called vortex air spinning process). The spinning unit 12 has to a vortex chamber 14 and a spindle 15 contained therein. In the spindle 15 is actually a preferably non-rotating spinneret. In the vortex chamber 14, an air vortex flow is generated by nozzles, which is a spinning of the fibers of the warped fiber structure 11 at the mouth causes the spindle 15. The yarn 13 produced thereby becomes corresponding withdrawn and wound on a winding device (not shown). How to get the Figure can be seen, the drafting 1 also the pair of rollers 7, which forms a Vorverzugsfeld 9 with the pair of rollers 3. It should be explicit again be pointed out that the inventive method for commissioning of a drafting system is not due to a particular spinning process, as shown here Air spinning method is limited, nor on the presence of the further pair of rollers 7th

FIG. 5 shows a control system 19 according to the invention, which according to the invention Procedure the drafting 1 starts operation. The rear one points to this Roller pair 4 has its own drive 18, as well as the front roller pair 3, which having the drive 17. If the drafting 1 still exists as shown here a further pair of rollers 7, which with the pair of rollers 3 a Vorverzugsfeld forms, so can the pair of rollers 7 driven by the drive 17 of the pair of rollers 3 be (or have its own additional drive). The inventive Control 19 controls the drives 17 and 18 during commissioning the drafting system according to the inventive method. The control 19 can with correspondingly further control and control devices of a textile machine be connected (entire textile machine not shown).

The method according to the invention may also include, depending on how Drawframe was previously parked that before putting the drafting system the sliver end 6 of the nip line 5 of the rear roller pair 4 is moved back becomes. This can also be done automatically, for example with the controller 19 and the drive 17. This is especially true when the sliver end 6 is not by hand at a predetermined distance from the nip line 5 of the rear roller pair 4 is separated. This is especially true for fully automatic piecing and devices desirable in which the drafting first so turned off is that the fiber structure 2 at the nip line 5 of the rear roller pair 4th tears off. This creates a clearly defined sliver end 6, which only still needs to be positioned accordingly before the drafting system returns to service can be taken.

The invention is not limited to the explicitly mentioned possibilities and embodiments limited. These variants are intended rather as a suggestion for the expert, to implement the idea of the invention as low as possible. Of the described Embodiments are therefore easily further advantageous applications and combinations derivable, which also reflect the idea of the invention and by this Registration should be protected. Some of the disclosed features have been in this Description combined and described in the following claims combined claimed. But it is also conceivable, individual features of this description on its own or in another combination in application of the inventive concept to claim. The applicant therefore expressly reserves before, if necessary, to provide other combinations in application of the inventive concept.

Legend

1

drafting system

2

fiber structure

3

front pair of rollers

4

rear roller pair

5

clamping line

6

Sliver end

7

roller pair

8th

Main drafting zone

9

preliminary drafting

10

yarn

11

warped fiber strand

12

spinning unit

13

yarn

14

swirl chamber

15

spindle

16

Rolls of the rear roller pair

17

Drive pre-delay

18

Drive rear roller pair

19

control

20

Strappy

U ₄ (t)

Speed curve behind roller pair 4

U ₃ (t)

Speed curve front pair of rollers 3

U _{A, 4}

Starting speed for the rear roller pair 4th

U _{A, 3}

Starting speed for the front pair of rollers 3

t _{S, 3}

Time for commissioning the front roller pair 3

t _{h, 3}

Period until the front roller pair 3 reaches the attachment speed U _{A, 3} (acceleration)

t _{h, 4}

Period until the rear roller pair 4 reaches the attachment speed U _{A, 4} (acceleration)

t _{EV, 3}

Period until the front roller pair 3 from the transient process has finished the acceleration

t _{EV, 4}

Period until the rear roller pair 4 the Einschwingungsvorgang from the Acceleration has ended

t _K

Time start piecing process

t _E

Timing end piecing process

t _AE

Period startup process

t _EVE

Time at which both roller pairs the transient process have finished

U _{B, 4}

Operating speed of the rear roller pair 4th

U _{B, 3}

Operating speed of the front roller pair 3rd

Claims (12)

Method for starting a drafting system (1) for warping a fiber structure (2), wherein the drafting system (1) includes a front pair of rollers (3) and a rear, a nip line (5) having pair of rollers (4), and wherein the commissioning of the drafting system (1) a fiber band end (6) is present, characterized in that
at start-up of the drafting system (1) the fiber composite end (6) only in the nip (5) of the rear roller pair (4) occurs when in the speed curve of the front roller pair (3) and the speed curve of the rear roller pair (4) of the transient is terminated from the acceleration, wherein the front and the rear roller pair (3, 4) preferably have constant rotational speed values when entering the fiber dressing end (6) in the nip line (5) of the rear roller pair (4). A method according to claim 1, characterized in that
before commissioning of the drafting system (1), the fiber composite end (6) is brought to the nip line (5) of the rear roller pair (4) at a predetermined distance, preferably this distance is 0.1 mm to 5 mm, preferably 3 mm or 4 mm. Method for starting a drafting system (1) for warping a fiber structure (2), wherein the drafting system (1) includes a front pair of rollers (3) and a rear, a nip line (5) having pair of rollers (4), and wherein the commissioning of the drafting system (1) a fiber band end (6) is present, characterized in that
before starting up the drafting system (1), the fiber composite end (6) is brought to the nip (5) of the rear roller pair (4) at a predetermined distance, preferably this distance is up to 6 mm, preferably this distance is 0.1 mm to 5 mm, more preferably this distance is 3 mm or 4 mm, preferably the distance is achieved by cutting the fiber band end (6). Method for starting up a drafting system (1) according to one of the preceding claims, characterized in that the drafting system (1) has at least one further pair of rollers (7), wherein the front and the rear pair of rollers (3, 4) preferably the main drafting zone (8 ) of the drafting system (1) form. Method for starting up a drafting system (1) according to one of the preceding claims, characterized in that the rear roller pair (4) represents the outlet roller pair of the drafting system (1). Method for starting up a drafting system (1) according to one of the preceding claims, characterized in that after or during start-up of the drafting system (1), a region of the warped fiber structure (2) is overlapped with a yarn end (10), preferably passes through the yarn end ( 10) also the nip line (5) of the rear roller pair (4). Method for starting up a drafting system (1) according to one of the preceding claims, characterized in that the drafting system (1) forwards the warped fiber structure (11) directly to a spinning unit (12) which turns the fiber structure (2, 11) into a yarn (1). 13), preferably the drafting system (1) and the spinning unit (12) are elements of a spinning station of a textile machine. Method for starting up a drafting system (1) according to Claim 7, characterized in that the spinning unit (12) spins the fiber structure (2, 11) into a yarn (13) by means of an air spinning process, preferably the spinning unit (12) has a vortex chamber ( 14) and a spindle (15). Method for starting up a drafting system (1) according to one of the preceding claims, characterized in that, when the fiber dressing end (6) enters the nip line (5) of the rear roller pair (4), the rollers (16) of the rear roller pair (4 ) have a peripheral speed of at least 300 m / min or that the fiber structure (11) immediately after leaving the nip line (5) of the rear roller pair (4) has a speed of at least 300 m / min. Method for starting up a drafting system (1) according to one of the preceding claims, characterized in that the entry of the fiber composite end into the nip line (5) of the rear roller pair (4) takes place at lower roller rotational speed values than the operating rotational speed values and subsequent to the Entry of the fiber composite end (6) in the nip line (5) of the rear roller pair (4), the rollers (3, 4, 16) synchronously ramp up to their operating speed. Control (19) for one or more drafting units (1) of a textile machine, characterized in that the control (19) for putting into operation of the drafting units or performs a method according to one of the preceding claims. Textile machine with one or more controls (19) according to claim 11.

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