EP0291484B1 - Method for continuous thread feeding from bobbins and device for carrying out this method - Google Patents

Description

The present invention relates to a method of continuous feeding of yarn from bobbins, more particularly allowing the continuous feeding of weft yarns going to weaving machines.

The invention also relates to a device implementing the method provided by the invention.

To feed the weft threads of a weaving machine continuously from the supply reels, an immediate change to a new reel must be ensured when the active reel is exhausted. For this, the coils are conventionally connected to one another by tying the end of the wire of a coil to the beginning of the wire of the coil which follows it. This traditional method has certain drawbacks, however.

A first disadvantage consists in the diffficulties which the passage from one reel to the other can cause. In addition, it often happens that the last part of the wire present on a spool is of poor quality because it was damaged during the starting of the winding.

Similarly, reeling anomalies can occur for the last part of the thread of a spool because the last turns present on the spool, instead of taking place regularly, slide on the spool and become tangled.

Another disadvantage of the traditional knotting of successive spools lies in the fact that for each new spool to be placed on the machine, it is necessary to detect not only the beginning of the new thread, but also the end of the previous thread, which can cause importance. wasted time.

From the document DE 886.115 there is known a method of continuous wire supply with several coils, which consists in detecting the moment when the wire of the supply coil is almost completely unwound and in connecting the wire coming from a new supply coil with the wire unwound by the first supply coil.

From document DE 2,700,974 it is also known that the wire of a first coil and the wire of a second coil can be presented close to each other, in order to effect a change of coil.

However, none of these documents offers a continuous method of feeding yarn into weaving machines which has the characteristic that the change of spool can be carried out without interrupting the weaving.

In order to achieve this objective, the invention relates to a method of continuous feeding of yarn from feed spools in a weaving machine in which the feeding of the yarn is carried out by the intermediary of a supplier, this supplier constituting a thread reserve allowing the unwinding of the thread from the supplier in an intermittent movement; said method being essentially composed of a wire feed from a first coil, the presence of a second supply spool, the start of the wire of which is brought close to the wire spooled by the first supply spool, detecting when the wire of the first supply spool is almost entirely spooled without being completely , the stopping of the supply and the connection of the start of the wire coming from the second supply coil with the wire unwound by the first supply coil, and the resumption of the supply of wire from the second coil, characterized in that the supply of wire from said first coil is stopped following two conditions, firstly, the detection of said moment, and secondly, the fact that the supplier is located in a state allowing an interruption of the feeding of the thread from the active coil for a brief instant, without interrupting the weaving; and in that the residual wire of the first supply reel is cut in order to allow the removal of this residual wire.

In order to meet the second condition, according to a first possibility, the supplier is only stopped when the reserve of yarn on the supplier reaches an optimal level according to the weaving process.

According to a second possibility, in order to meet the second condition as quickly as possible, the detection of the quasi-exhaustion of the wire reserve on the first supply reel is followed by the constitution of an additional wire reserve on the supplier by rotating it, for a given time, at maximum speed.

It is clear that according to the method which we have just outlined, the last meters of wire present on each reel are rejected during the passage to the next reel, so that the defective ends of wire mentioned above are not brought in the weaving machine. It is also clear that all the drawbacks listed above and related to the traditional knotting method are eliminated by the method presented.

According to the method according to the invention, the device for monitoring the active supply coil, rather than detecting the exact moment at which the first supply coil is fully unwound, captures the moment when it is almost completely wound up, without the 'be completely, that is to say the moment when there are still a few meters of wire on the spool. In the case of weaving machines, this has the particular advantage that the time of stopping the supply of yarn to allow connection with the next supply spool can be chosen optimally according to the weaving cycle. . Likewise, this early detection makes it possible to take all the measures to stop for a brief instant the feeding of the thread from the active reel, without however interrupting the insertion of the weft nor, consequently, the weaving. For example, one could choose to interrupt the supply of yarn to a supplier of a weaving machine by stopping the yarn guide arm when the supplier's drum carries a maximum quantity of yarn; in this situation, it is both possible to tie a new feed reel and take, on the drum, the number of pick lengths necessary for weft insertions during the passage from one reel to another. A variant of this method could consist in increasing the supplier's rotation speed for a short period, so as to provide an additional thread reserve on the drum. If such a reserve is established, the supplier may be immobilized for a fairly long period while providing the desired number of picks; in this case, there is ample time to tie a new supply reel. The device implementing the method provided by the invention mainly consists of elements intended to present the beginning of the thread of the new supply reel facing the thread being unwound, detection elements intended to follow the unwinding active supply coils and connection elements intended to connect the two wires when passing from one coil to the next coil. The construction of such devices is explained in detail in the following paragraphs.

• Les figures 1 à 4 représentent un dispositif conforme à l'invention en vue d'illustrer pas à pas la méthode prévue par l'invention;
• la figure 5 représente un agrandissement de l'élément portant le repère F5 sur la figure 2;
• les figures 6 à 8 représentent graphiquement, en fonction de la réserve de fil présente sur une bobine d'alimentation, la vitesse de rotation d'un fournisseur et la réserve de fil présente sur le fournisseur, dans le cas où l'on a constitué une réserve supplémentaire de fil sur le fournisseur, comme décrit précédemment;
• les figures 9 à 11 représentent un second dispositif conforme à l'invention.

In order to better highlight the characteristics of the invention, the description of some installations using the method provided by the invention will be found below, by way of examples without limitation, with reference to the accompanying drawings, or:

• Figures 1 to 4 show a device according to the invention in order to illustrate step by step the method provided by the invention;
• Figure 5 shows an enlargement of the element marked F5 in Figure 2;
• Figures 6 to 8 show graphically, as a function of the wire reserve present on a supply reel, the speed of rotation of a supplier and the wire reserve present on the supplier, in the case where one has constituted an additional supply of thread on the supplier, as described above;
• Figures 9 to 11 show a second device according to the invention.

According to FIGS. 1 to 4, the supply of thread 1 to a device such as a supplier 2 of a weaving machine can be carried out by the unwinding of the thread from a first supply reel 3, this thread passing through example with a guide eyelet 4.

To carry out the continuous supply of wire provided for by the invention, the installation as shown in FIG. 1 further comprises a second supply coil 5, a device 6 intended to present the start 7 of the wire 8 of the second supply coil 5 near the wire 9 of the first supply coil 3, a connection device 10 intended to connect the wires 8 and 9, as well as sensors 11 and 12 intended to monitor the reserves of wire on the coils 3 and 5, these sensors being connected, for example, to a control unit 13 responsible for controlling the connection device 10. The device 6 intended to present the start of wire 7 near the wire 9 unwound by the coil active consists, in the first embodiment shown, of two guide eyelets 14 and 15 placed side by side and through which pass, respectively, the wires 8 and 9; as well as a wire clamp 16 retaining the start 7 of the wire coming from the second supply reel 5. The connection device 10 can be either a knotter or a splicer. The splicing is a particularly suitable method because of its speed, because it does not cause any local weakening of the wire and because it guarantees the continuity of the wire; in other words, a spliced wire can be woven without compromising either the operation of certain sensitive organs downstream, or the final appearance of the woven product.

The successive phases of the operation of the installation are shown diagrammatically in FIGS. 2 to 4. At the stage illustrated in FIG. 2, the sensor 11 finds that the reserve of wire on the supply coil 3 is practically exhausted, but is not absolutely. The control unit 13 then deactivates the supplier so as to end the feeding of the wire 1, and activates the connection device 10. The start 7 of the wire unwound by the second supply coil 5 is connected to the wire 9 of the first spool 3. The residual thread 17 remaining on the supply spool 3 is cut by the thread cutter 18.

these operations create the situation represented in FIG. 3, in which the wire can again be delivered to the supplier 2 by the supply device 1. The first supply coil 3, that is to say the bobbin 19 and the residual wire 17 are then removed from the spool holder.

In a following phase, a new supply coil 20 is mounted in place of the coil 3 almost entirely unwound; the wire of this new coil is then positioned in the wire clamp and becomes the start of wire 7. The sequence of operations just described can then be repeated, with a passage from coil 5 to coil 20 , similar to the previous passage between the coils 3 and 5.

The mode of detection of quasi-exhaustion of the coil 3 by means of the sensor 11 is illustrated in FIG. 5. The optical sensor 11, placed next to the supply coil 3, sends a signal 21 which is reflected by the coil 19 and which is detected by the sensor 11. It is clear that the coil 19 will only reflect the signal when the number of turns present is reduced and the surface of the coil 19 becomes visible. To ensure the reflection of the optical signal 21, the coil 19 can be covered with a highly reflective coating affecting, for example, the shape of a spiral ribbon 22.

As we have already mentioned in the introduction, the activation of the sensor 11 can be followed either by the constitution of an additional wire reserve on the supplier 2, before the termination of the connection from the start from wire 7 to wire 9. The conditions of this process are represented schematically in the graphs of FIGS. 6 to 8.

During the normal feeding of the wire 1 from a reel, for example the first supply reel 3 in the description above, the quantity of wire A present on this reel decreases regularly, phenomenon shown for reasons of simplicity by the downward curve 23 of FIG. 6. During the normal operation of the supply, the speed of the supplier 2, for example the number of turns made by the wire guide arm 24, can vary between a minimum value N1 and a maximum value N2, condition represented by curve 25 in FIG. 7. Generally, the wire reserve R on the drum will also vary between two values R1 and R2, as represented by curve 27 in FIG. 8; this variation is due on the one hand to the variation in the number of turns made by the wire guide arm 24 and, on the other hand, to the unwinding of the wire 9 according to an intermittent movement at the start of the drum 26.

When unwinding the supply reel 3, the quantity of wire A will reach a predetermined minimum value A1 at a time t1, after which the sensor will send a signal to the control unit 13. From then on, the supplier 2 will switch to its maximum speed N2, to which it will be maintained for a given period X. It is clear that this rise in speed will have the effect of further reducing the quantity of wire A present on the first supply reel 3, at the same time as the reserve of wire R present on the supplier 2 increases. From the moment t2 when the wire reserve on the supplier 2 has reached a predetermined maximum value R3, the supplier will be deactivated and braked until it stops. However, the weaving machine remaining in activity, the maximum yarn reserve R3 will be brought back in a short time to an absolute minimum R0. At this time t3, the supplier will have to be activated again so that the drum 26 can deliver at least one length of pick during the next insertion. The period T corresponding to the total shutdown of the supplier 2, and which is substantially equal to the difference t3 - t2, here represents the connection time from the start 7 of the wire of the second supply coil 5 to the wire 9 of the first supply coil 3 using the connection device 10. It is clear that the size of the wire reserve R3 determines the length of this period T.

FIG. 9 represents a reel holder 28 consisting of a conveyor belt successively presenting the feed reels in front of the feed device and implementing the method provided by the invention. The device 6 mentioned above, and intended to present the start 7 of the wire of the second supply coil 5 near the wire 9 of the first supply coil 3, in this case consists essentially of the wire clamp 16 mentioned above, placed here near the guide eyelet 4, and a movable wire guide 30 which, when the first coil 3 is almost exhausted, can move the wire 9 a certain distance to place it in a substantially parallel position relative to the wire 8 of the second coil 5. This operation is illustrated in FIG. 10. After the paralleling, the connection device 10 is activated to join the wires 8 and 9 either by knotting or by a splice. Driven by the conveyor belt, the new spool is then placed in the position illustrated in FIG. 11. FIG. 11 also represents the way in which the start 7 of the thread coming from the following supply spool 20 can be sought by a wire finder 31. This can consist, for example, of a vacuum cleaner nozzle covering the surface of the supply coil 20 and capable of taking the start of wire 7, which can then, using an eye-catching device not shown in the figure, be brought before the wire clamp 16 to be retained there. The bobbin of the old supply coil, carrying the turns of residual wire 17, is evacuated.

It should also be noted that the spool holder 28 illustrated in FIGS. 9 to 11 requires only a single sensor 11, intended for controlling the quantity of wire present on the supply spools, since the transport belt will always have brought them in the same place when the wire is almost exhausted during unwinding.

Claims (12)

1. Method of continuous feeding of thread from the feed coils in a weaving machine in which the entry of the thread is effected by means of supply mechanism, said supply mechanism consisting of a reserve stock of thread allowing the unwinding of the thread departing from the supply mechanism by an intermittent movement, said method essentially consisting of feeding a thread leaving a first coil (3); the presence of a second feed coil (5) whose beginning of the thread (7) is brought into the proximity of the thread (9) unwound from the first feed coil (3); the detection of the moment in which the first feed coil (3) is nearly completely unwound without being completely so, stopping the supply and connecting the beginning (7) of the thread coming off the second feed coil (5) to the thread unwound from the first feed coil (3); and resuming the feeding of thread from the second coil, characterized in that the feeding of the thread off said first coil (3) is carried out upon stopping on two conditions, firstly, the detection of said moment and secondly the fact that the supply mechanism is able to allow the introduction of the thread leaving the active feed coil to be interrupted for a short while; apart from that without interrupting the weaving; and in that the remaining thread (17) of the first feed coil (3) is cut in order to allow removal of that remaining thread (17).

2. Method according to claim 1, characterised in that the detection of the approaching exhaustion of the reserve thread on the first feed coil (3) is followed by the forming of an additional reserve of thread (R3) on the supply mechanism (2) by making this one rotate, in a given time (X), at maximum speed (N2), after which the supply mechanism will be stopped and the beginning (7) of the thread leaving the second coil (5) will be connected again with the thread wound off of the first feed coil (3).

3. Method according to claim 1, characterised in that following the detection of approaching exhaustion of the reserve thread on the first feed coil (3), the supply mechanism (2) is not stopped before the reserve of thread (R) on the supply mechanism (2) reaches an optimal level, knotting the beginning of thread (7) coming off the second feed coil (5) and thread (9) unwound from the first feed coil (3) only takes place afterwards.

4. Method according to one of the aforementioned claims, characterised in that detection of approaching exhaustion of the first feed coil (3) is effected by an optical device and based on the reflection of a signal on the core (19) of the first feed coil (3) when it is nearly completely unwound without being completely so.

5. Method according to one of the aforementioned claims, characterised in that the beginning of the thread (7) coming off the feed coil (5) is reconnected by a splice in the thread (9) unwound from the first feed coil (3).

6. Method according to one of the aforementioned claims 1 to 4, characterised in that the beginning (7) of the thread coming off the second feed coil (5) is reconnected by knotting to thread (9) unwound from the first feed coil (3).

7. Device suitable to apply the process according to one of the claims 1 to 6, especially in a weaving machine in which the introduction of the thread is effected by means of a supply mechanism, said device consisting of the elements (6) intended to introduce to each other, the beginning (7) of the thread leaving the second feed coil (5) and the thread (9) unwound from the first feed coil (3); of sensors (11,12) intended to identify the moment in which the active feed coil is almost unwound without being completely so; and of elements (10) intended to reconnect said two threads (7,9) characterised in that this device contains a control unit (13) connected to said sensors (11,12) and said elements (10) intended to reconnect the threads (7,9) preventing the control of said elements (10) according to the two conditions mentioned.

8. Device according to claim 7, characterised in that the elements (6) intended to bring together the beginning (7) of the thread coming off the second feed coil (5) and the thread (9) unwound from the first feed coil (3), essentially consist of two guiding eyelets (14,15) placed side by side, respectively guiding, the beginning of thread (7) and the thread (9), as well as a thread pincer (16) holding the beginning of thread (7).

9. Device according to claim 7, characterised in that the elements (6) intended to bring together, the beginning (7) of the thread coming off the second feed coil (5) and the thread (9) unwound from the first feed coil (3), essentially consist of an eyelets (4) guiding the thread (9) of the first feed coil (3), a thread pincer (16) holding the beginning (7) of the thread unwound from the second feed coil (5) and bringing this beginning (7) into the neighbourhood of thread (9) unwound from the first feed coil (3), as well as a movable thread guide (30) able to work on thread (9) unwound from the first feed coil (3) in order to carry it against or practically against the beginning (7) of the thread unwound from the second feed coil (5).

10. Device according to one of the claims 7 to 9, characterised in that it as well contains a thread seeker (31) allowing attaching the beginning (7) of the thread of each newly presented coil (20) and taking this beginning of the thread to the thread pincer (16).

11. Device according to one of the claims 7 to 10, characterised in that the aforementioned sensor (11) or sensors (11,12) are optical receivers watching the core (19) of the active feed coil (3) and working on the basis of the reflection of an optical signal (21) on that core.

12. Device according to claim 11, characterised in that the surfaces of the cores (19) of the utilized feed coils (3, 5, 20) is equipped with a highly reflective ribbon (22).

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