EP0651078B1 - Process for centrifugal spinning - Google Patents

Description

The present invention relates to a spinning method centrifugal designed to continuously produce a length of wire indefinite, according to which one alternately feeds two pots centrifugal spinning through two supply lines respective, both born at the exit of a train stretcher, periodically separating the wire at the junction of the two conduits, communicating a pretortion to the bundle of fibers leaving the stretching train by an air jet helical and directing this end into the other said conduits, the wire is pinched along its path between said junction and the spinning pot in which it is brought, to stop the rise of the twist along the wire, beyond the pinch zone to periodically separate the wire.

We already know such a centrifugal spinning process described in EP-A1-515,762. In this document, the end back of wire, severed at junction, wound against the inner face of a spinning pot, is directed on a winding coil by an air jet.

In the application EP-A-0 556 528 which constitutes the closest prior art, the air jet is replaced by a pusher which applies the wire against a spool of storage at the precise moment when the wire is cut at the junction of the two conduits. It appears that the synchronization of these two mechanical functions is difficult to guarantee and that lags can occur over time. Therefore, it there is a risk that the pusher may come up against the surface of the storage reel after the cut end has passed some thread. In this case, this end goes into the jar spinning and the spinning process is interrupted. Another disadvantage of this solution lies in the use of a knife to cut the thread, as far as it is periodically necessary to sharpen the blade. Indeed, if the knife no longer cuts well, the wire is not cut cleanly and little by little fibers can accumulate and prevent the device to operate following a jam caused by this accumulation.

The object of the present invention is to remedy the disadvantages mentioned above.

To this end, the subject of this invention is, first of all a centrifugal spinning process for producing a wire in device according to claim 1, as well as a device for centrifugal spinning intended to produce a continuous wire according to claim 2.

The advantages of the invention are obvious. There is no more synchronization to be ensured between the cutting member and the pusher responsible for retaining the wire by applying it against the storage reel. Since it's the pinch of the wire which creates the conditions for a separation of the wire following the loss of cohesion between the fibers due to stopping the rise in torsion from the point of pinching of the wire, the risk of leaving the end of the wire leaving in the pot no longer exists, since the very condition of the separation of the wire is the prior pinching thereof. Consequently, this separation no longer requires a cutting member and pneumatic action is sufficient to separate the wire at the junction. As soon as the end thus released from the wire coming out of the stretching train enters the conduit leading to the other pot, it enters a helical air flow who communicates to him a pretortion intended to give him back a cohesion capable of reaching the other spinning pot. It's that same helical air flow which creates the vacuum sucking the wire in the conduit leading to the other spinning pot. The risk of jamming of the cutting member, due to wear of the blade, are removed. So we can see that the reliability of the spinning process is found considerably improved by the present invention and that this improvement further results from a simplification of the spinning device going in the direction of reducing the cost of this device, as well as a reduction in the cost of its maintenance. This invention therefore constitutes an important element, intended to make Advance centrifugal spinning whose advantages potential are considerable, since it makes it possible to produce at higher speed than the ring cursor system a wire of equivalent or even higher quality.

The attached drawing illustrates, schematically and by way of example of an embodiment of a spinning device for the implementation of the process which is the subject of the present invention.

Figures 1 to 4 are four sectional elevation views of the spinning device illustrating four phases characteristics of the spinning process.

The figures in the drawing show in detail the elements which relate directly to the present invention. For those whom it concerns the operation, the driving of the coils storage, the passage of the wire from the storage coils to that of winding, as well as the connection of the different lengths of wire stored on the storage spools during their winding on the winding coil, these elements have not been represented or described here and we can refer for more details on this subject in patent application EP-A-0 556 528. This document shows in particular the manipulation of lengths of wire to obtain a continuous wire wound without interrupt on the same winding coil which is called to reach a standard size.

The spinning device which is the subject of the invention comprises a stretching train of which only the output, in the form of two rollers 1, 2 is shown. A conduit 3 is arranged for collect the drawn bundle of fibers 4 leaving the drawing train. This conduit 3 is divided into two branches 5 and 6 whose outlets are aligned on two 5 'conduits, respectively 6 ', which lead respectively into two centrifugal spinning pots 7 and 8. Mechanisms for spread the wire along the inner walls of the pots are not not shown, but can be like those shown and described in EP-A1-515,762.

Two storage coils 9 and 10 are arranged in the space separating the conduits 5 and 6 from the conduits 5 'and 6'. With respect to each of these storage coils 9 and 10, of the other side of the path of the wire passing from the outlet of the conduits 5, 6 at the entrance to conduits 5 ', 6', there is a pusher 11, 12 secured to a piston 13, respectively 14, mounted in a pneumatic cylinder 15, respectively 16, at against the pressure of a return spring 17, respectively 18. A winding coil 19 is intended for collect the wire from the storage coils 9 and 10, by example, as described in the aforementioned EP 925000015.0, this part of winding the wire not being necessary for the understanding of the present invention.

A series of nozzles 20 is distributed angularly around of conduit 3. These nozzles are selectively connected by through a timer 21 to an air source under pressure S. These nozzles 20 are arranged so as to create, in the duct 3, a helical air flow under pressure directed downstream. Two other series of nozzles 22 and 23 are arranged downstream in each of branches 5 and 6. They are selectively connected to the air source under pressure S by timer 21 and a switching valve 24. These nozzles 22 and 23 are also oriented to form a helical air flow in branches 5 and 6.

Two additional nozzles 25 and 26 can be directed in the axis of the wire at the birth of each branch 5 and 6 and located in the plane common to these two branches. These nozzles 25 and 26 are selectively connected to the source of pressurized air S by the timer 21 and the valve switching 24.

The pressurized air source S is still connected selectively, via timer 21 and the switching valve 24, with two pneumatic cylinders 15, 16, as well as two ejectors 27 and 28, located along the ducts 5 'and 6', respectively, to create a vacuum at the entrance to these conduits.

As can be seen, the switching valve 24 switches the pressure source S on two circuits separate, A and B, circuit A supplying the series of nozzles 22, the nozzle 26, the pneumatic cylinder 16 and the ejector 27, circuit B supplying the series of nozzles 23, the nozzle 25, the pneumatic cylinder 15 and ejector 28. The series of nozzles 20 is powered whenever the timer connects the circuits A or B at the source of pressurized air S.

We will now describe the various stages of the spinning process, object of the invention, using the four drawing figures.

Figure 1 illustrates a phase of the spinning cycle at during which the wire of the centrifugal spinning pot 7 is transferred to the storage reel 9, while the wire is in spinning course in the other pot 8. Simultaneously, the wire previously wound on the storage reel 10 is transferred to the winding coil 19.

After a determined time, corresponding to a certain degree of filling of the spinning pot 8, the timer switches the switching valve 24 on circuit A above, which is drawn in a strong line in FIG. 2, which illustrates the effect produced by this pressurization of the circuit A. When circuit A is pressurized, the pusher 12 clamps the wire against the storage reel 10. This pinching the wire isolates the part of the wire located between the pinch point and the exit of the stretching train 1, 2 of the source of torsion communicated to the wire by the pot of spinning 8. Simultaneously, the nozzles 20 communicate a twist to that portion of the wire. As at the same time the nozzles 22 exert a vacuum at the inlet of conduit 5 and that the nozzle 26 can project a jet of pressurized air against the wire, this one, presenting practically no more cohesion, is breaks in the place where it is stressed by the depression due to the nozzles 22 and by the jet from the nozzle 26. The coil of storage 10 rotated in the direction of the arrow wind both the portion of wire leaving the conduit 6 and the wire from the pot 8. As for the end of the fiber bundle leaving the stretching train 1, 2, it is immediately subjected to a twisting effect by the nozzles 20, so that this beam of fibers regains cohesion. To guarantee regularity of the twist, the distance between the pinch point of the rollers 1, 2 and the nozzles 20 is chosen lower than the average fiber length. Then at the entrance to junction 5, the wire receives a communicated S-twist by the nozzles 22, which gives it a cohesion suitable for reach the spinning pot 7.

Taking into account the speed of the machine in "work" and the reduced length of the fiber bundle in the conduit (3), these fibers not to be twisted for the purposes to facilitate separation, the delay between the nozzle (20) and the nozzles (22, 23) must be a few fractions of a second, which is not possible with the "sensitivity" of technology the timer; computerized means of control are preferable.

As soon as the spinning is started in the pot 7, the pressure in circuit A is interrupted and we are in the situation illustrated by figure 3.

Once pot 8 is emptied, there is again change of spinning pot as illustrated in figure 4. It it is exactly the opposite operation to that described in relationship with Figure 2, i.e. it is circuit B mentioned above which is under pressure, operations described for Figure 2 occurring exactly the same way but in reverse, that is, the wire passes then from the spinning pot 7 to the spinning pot 8.

This cycle also repeats continuously as long as necessary.

Claims (5)

1. Process for centrifugal spinning designed to continuously produce a yarn having an indefinite length according to which two centrifugal spinning cans (7, 8) are alternatively fed through two respective feeding conduits (5, 5', 6, 6') both starting from the exit of a roller draft device (1, 2), periodically separating the yarn at a junction of the two conduits imparting a pre-twisting to the bundle of fibres which exits through the roller draft device by an helical air jet and directing one yarn end to the other of said conduits, the yarn of each spinning can being transferred on a storage bobbin (9, 10) by an actuated pusher (11, 12) which nips that yarn along its path between said junction and the can and applies it against said storage bobbin at the precise moment when the yarn is separated, characterized in that for periodically separating the yarn while nipping the yarn a suction is simultaneously produced in the other of said conduits (5, 6) creating a helical air flow in the direction of the spinning can (7, 8) which the yarn must be fed into, so that the portion of the yarn located at the junction of the two conduits, isolated from the twisting source due to the nipping of the yarn loses its cohesion and is taken apart from the rest of the yarn under the effect of the suction produced in the other of said conduits, within which the helical air flow causing it to advance in the direction of the other spinning can by submitting it to a pre-twisting, stopping said helical flow once the yarn comes into contact with the internal face of the centrifugal spinning can and the operation is repeated in the opposite direction, an so on as many times as it is wished.
2. Device for centrifugal spinning comprising two centrifugal spinning cans (7, 8) alternatively fed by a roller draft device (1, 2), two conduits (5, 5', 6, 6') ending each to one of the said cans (7, 8) and starting from a junction where the conduits branch from, said junction being located at the exit of a common duct (3) having an inlet adjacent to the exit of the roller draft device (1, 2), means (22, 23) adjacent to said conduits to divide the yarn into two and to lead it within the other of said two conduits, each of said conduits comprising two aligned portions (5, 5', 6, 6') separated by a gap, where at one side of the yarn path a bobbin (9, 10) receives the yarn produced within the spinning can to which said conduit ends and at the other side of said yarn path a pusher (11, 12) is driven by a pneumatic means (15, 16) for nipping the yarn against the surface of said bobbin, characterized in that said means adjacent to said conduits to divide the yarn comprise pneumatic means (22, 23) such as nozzles to produce in a substantial way simultaneously to said pusher (11, 12) driving, an helical air flow in a part of the conduit (5, 6) extending between said junction and said gap leading to the other spinning can.
3. Process according to claim 1, characterized in that, simultaneously to the production of said helical air flow in the other of said conduits, an air jet (25, 26) is directed against the yarn upstream said conduit and in the direction thereof.
4. Process, according to the claim 1, characterized in that, at each of the interventions of one or the other means (22, 23) to produce said helical air flow, a nozzle (20) arranged in the duct (3) at the roller draft device exit is driven and acts with a predetermined delay with respect to the former ones.
5. Process, according to claim 4, characterized in that, at the exit of the roller draft device (1, 2) an helical twist is imparted by means of the nozzle (20) and therefore at the two following nozzles (22, 23) of conduits (5, 6) twisting is carried out in the same direction as the one imposed by the centrifugal spinning can.

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