EP0219437B2 - Shedding mechanism for looms with a tiltable retaining hook - Google Patents

Description

It is known that in the devices for forming the crowd of a loom, it is possible to use for the lifting of each arch a system composed of two movable hooks each subject to the end of a funicular element, which cooperates with a lifting beam associated with said arch. The two movable hooks are alternately raised and lowered by knives provided in the crowd-forming device, while elastic blades with curved ends associated with an electromagnet are placed in the upper part of each system to possibly retain the hook corresponding in high position.

One end of the blades in question must be embedded in a block, while its other curved end cooperates with the corresponding hook. The blades are provided in spring steel so as to be elastic. It is easy to understand that such an arrangement is not reliable, because the leaf springs are subjected to continuous bending forces at a very high rate when it comes to controlling warp threads in a weaving loom. great speed. There are therefore frequently ruptures of these blades which result in the immobilization of the material causing an increase in production costs, without counting the actual repair costs.

In addition, because the magnetic circuit includes each elastic strip, it can be seen that its reduced section limits the value of the flux passing through it all the more, so that the power of each electromagnet is reduced.

Finally, the blades are made of spring steel, therefore carbon steel, so that they have a remanence which can harm the proper functioning of the selection.

It is also known that in the above device, the movable hooks include a pusher suitable for applying the retaining blade against its electromagnet at the end of its travel.

Finally, we know from document DE-A-2 204 815 a crowd formation device comprising two hook traction members animated back and forth connected together by a funicular element passing over a pulley and susceptible to cooperate with two tilting hooks loaded by a tension spring so that they are each distant from a corresponding electromagnet capable of keeping them in a release position if they are excited.

It is easy to understand that such a device is bulky because of its structure comprising a large number of electromagnets and the architecture of the tilting hooks. Such a device cannot therefore be suitable for producing a compact weave mechanism intended to control a very large number of heddles

The improvements which are the subject of the present invention aim to remedy the aforementioned drawbacks of the fixed hooks of the crowd formation devices in question, and it aims at the production of a rigid retaining hook of economical manufacture, the operation of which is reliable and which ensures an unreduced passage of the magnetic flux.

To this end, the crowd-forming device according to the invention comprises a plurality of systems which each include two movable hooks connected by a funicular element as well as two fixed hooks each produced in the form of an element rocking around a horizontal axis, associated with a compression spring and actuated by an electromagnet which keeps it in the retracted position relative to the corresponding movable hook, said systems being arranged between two vertical separating partitions assembled together, and constituting in pairs a support for the electromagnet, the curved head or beak with oblique end edge of each hook being located in its rest position above the chin of the corresponding movable hook, each fixed hook being provided with an upwardly facing tail, arranged in a vis- opposite the core of the electromagnet and subjected to the reaction of the compression spring, so that its head overlaps rbée is in the rest position above the chin of the corresponding movable hook, the retaining electromagnet of said fixed hook acting on its tail to keep it in the tilted position with its head curved or beak located in the erased position towards the outside relative to the chin of said corresponding movable hook when the latter swings the fixed hook to apply its tail against said electromagnet, each movable hook being provided with an elastic tongue oriented in the direction of movement of said hook and of which the external face is offset towards the outside with respect to the external face of the chin so that this face cooperates with the end wall of the curved head or beak of the corresponding hook, the edge of the tongue of each of its movable hooks being inclined in the same direction as the edge of the beak of the corresponding fixed tilting hook.

• La fig. 1 est une coupe transversale d'un dispositif de formation de la foule comportant application des perfectionnements suivant l'invention.
• Les fig. 2 à 7 illustrent en vue de détail à plus grande échelle le fonctionnement du crochet de retenue du dispositif suivant l'invention.

The appended drawing, given by way of example, will allow a better understanding of the invention, the characteristics which it presents and the advantages which it is capable of providing:

• Fig. 1 is a cross section of a crowd formation device comprising application of the improvements according to the invention.
• Figs. 2 to 7 illustrate in detail on a larger scale the operation of the retaining hook of the device according to the invention.

As described in patent application FR-A-25 86 432 filed on August 23, 1985 of the present owner, a device for training the crowd of a mete weaving tier comprises a plurality of systems 1 for lifting the warp threads, each of them being arranged between two dividing partitions 2. Each system comprises two mobile hooks referenced 3, associated with each of the ends of a funicular element 4 passing around a pulley 5 of a spreader 6 whose other pulley 7 is surrounded by the yoke 8 which is anchored by one of its ends to a fixed point 9. Each of the hooks 3 is alternately moved back and forth by means of knives 10, 11 moving back and forth. Thus, each hook is alternately brought to the level of the head 1 a of the system 1 where it can be gripped by a retaining hook 12 established in accordance with the invention.

It is observed that each system 1 is retained with respect to two transverse bars 13 and 14 against which shoulders 1b and 1c of the system bear, while a notch 1 d at the bottom of the system rests against a cross member 15 or vice versa.

As more particularly illustrated in detail in FIG. 2 to 7, each retaining hook 12 is mounted tilting about an axis 16 oriented perpendicular to the path of the movable hooks 3, that is to say that it is in fact in a horizontal position in the nonlimiting example illustrated, and it is retained by the two separating partitions 2 of each system 1. The hook 12 therefore has a central boss provided with a bore that the axis 16 passes through. It is furthermore provided with a tail 12a oriented upwards, and with a head 12b turned downwards and provided with an inverted end or spout 12c. A compression spring 17 is placed between the tail 12a and a fixed abutment of the head 1 a so that the inverted end or spout 12c of the hook is, in the free position, facing the chin 3a of the hook fixed 3 correspondent. We observe the presence of an electromagnet 18 placed in the head 1a and whose core 18a is opposite the end of the tail 12a of the hook 12. The terminal edge 12d of the head 12b of the hook is oblique in the same direction as the corresponding edge 3b of the chin 3a of the hook 3.

It is noted that each movable hook 3 comprises, unlike that illustrated and described in the aforementioned application FR-A-25 86 432 of the present holder, not a rigid plunger, but an elastic tongue 3c oriented in the direction of movement of the hook and whose role will be better described later.

Operation follows from the foregoing explanations.

As illustrated in fig. 2, in the rest position, the hook 12 is in the tilted position as a result of the reaction of the spring 17, so that its edge 12d is opposite that of the bead 3a of the hook 3a of the hook 3. During the elevation of the knife 10 to which the hook 3 is associated by an oblique lateral beak 3d, and towards the end of the movement, the extreme edge 3b of the chin 3a of the hook 3 comes into contact with that 12d of the head 12b of the retaining hook 12 , so that the corresponding slope of these two edges causes this hook to tilt clockwise until the two end walls 12e and 3e of the two bodies in question come against each other, as illustrated in fig. 3. At this moment, it is observed that the tail 12a of the hook 12 considered is not yet in abutment against the core 18a of the electromagnet 18 (see game J _i ). The travel of the movable hook 3 continues, under the effect of the reaction of the spring 17, the spout 12c of the head 12b of the fixed hook 12 engages under the chin 3a of the hook 3, as shown in FIG. 4. Since this position is slightly before the top dead center of each hook 3, when the latter rises a little more, the edge 3f of the tongue 3c causes the hook 12 to tilt due to its slope and of that of the edge 12d of this hook 12. The race continuing, the end wall 12e of the latter comes to cooperate with the external lateral wall 3g of the elastic tongue 3c of the hook 3. This wall is, as illustrated, more on the outside as the end face 3e of the hook 3. Thanks to its elasticity, the tongue 3c therefore maintains the tail 12a of the corresponding hook 12 in energetic support against the core 18a of the electromagnet, so that on the one hand the contact is perfect and that on the other hand the possible wear is compensated. The representation of fig. 5 corresponds to the top dead center of the travel of the hook 3.

If the selection of the crowd formation device requires that the hook 3 does not remain in the high position, the electromagnet is excited, so that the tail 12a of the fixed hook 12 remains stuck against the core 18a of said electro- magnet. When the knife 10 descends (fig. 7), the chin 3a of the hook 3 escapes the beak 12c of the head 12b of the hook 12, as illustrated in fig. 7. It is observed that, in this position, the end wall 12e of the head 12c is located outside the external face 3e of the chin 3a of the hook 3, following a clearance J ₂ .

On the contrary, if the hook 3 must remain in the high position, the electromagnet 18 is not excited, so that during the downward stroke of the knife 10, the end wall 12e of the spout 12c of the head 12b of the hook 12 slides against the side wall 3g, then against the edge 3f of the tongue 3c of the hook 3, so that it comes as illustrated in FIG. 6 engage under the chin 3a of the movable hook 3, under the influence of the reaction of the compression spring 17. The knife 10 continues to descend to its bottom dead center from which it rises to cooperate with the spout lateral 3d of the hook 3. This performs a stroke c (fig. 5) upwards from the position of fig. 4 to bring the beak 12c of the hook 12 against the side wall 3g of the tongue 3c, then during the descent of the knife 10, depending on whether the electromagnet will be excited or not, the hook 3 will descend or remain attached to that 12 .

In a preferred embodiment, the electro- magnet is unique for each system 1, that is to say that, when excited, it can retain either one or the other of the two hooks 12, when their tail 12a is pressed against its core 18a.

Although the above description refers to a vertical orientation of the assembly 1, it is easily understood that it could be arranged in any other direction without departing from the scope of the invention.

Claims (1)

1. Device for forming the shed of a weaving loom of the type comprising a plurality of systems (1), each of which comprises two movable hooks (3) connected by a funicular element (4), as well as two fixed hooks (12), each one being produced in the form of an element tilting about a horizontal pin (16), being associated with a compression spring (17) and being actuated by an electromagnet (18) which holds it in the retracted position with respect to the corresponding movable hook (3), the said systems being arranged between two vertical separating partitions assembled together and each pair constituting a support for the electromagnet (18), the curved head or nose with an oblique terminal edge of each fixed hook (12) being located in its rest position above the toe (3a) of the corresponding movable hook (3), each fixed hook (12) being provided with a shank (12a) pointing upwards, arranged facing the core (18a) of the electromagnet (18) and subjected to the reaction of the compression spring (17), so that its curved head (12c) is in the rest position above the toe (3a) of the corresponding movable hook (3), the electromagnet (18) for retaining the said fixed hook (12) acting on its shank (12a) in order to hold it in the tilted position with its curved head or nose (12c) located in a position which is retracted outwards with respect to the toe (3a) of the said corresponding movable hook (3) when the latter causes the fixed hook (12) to tilt in order to apply its shank (12a) against the said electromagnet (18), each movable hook (3) being provided with an elastic tongue (3c) pointing in the direction of displacement of the said hook (3) and whose outer face (3g) is outwardly offset with respect to the outerface (3e) of the toe (3a) so that this face (3g) interacts with the end wall (12e) of the curved head or a nose (12c) of the corresponding hook (12), the edge (3f) of the tongue (3c) of each of its movable hooks (3) being inclined in the same direction as the edge (12d) of the nose (12c) of the corresponding fixed tilting hook (12).

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