EP0990723A1 - Weft insertion device - Google Patents

Abstract

The weft insertion mechanism to carry the weft through the shed, in a gripper loom, reduces the gripping force at the insertion lance (1) as it nears the zone (16) where the weft is to be transferred to the pick-up lance (20). The gripping force at the pick-up lance (20) is increased as it nears the weft transfer zone (16). A magnet unit (17) is on the beating face at the weft transfer level (16), to give a magnetic field which acts on a swing unit (9) at the insertion lance (1) and a swing unit (29) at the pick-up lance (20). The swing units (9,29) at the lances (1,20) are of a ferromagnetic material, placed at their pincer grip sections. The insertion lance can be fitted with a magnet, with an opposing polarity to the fixed magnet (17), and the pick-up lance has a magnet of identical polarity to give the required effects on the lance pincer swing units. The lances can also have a second magnet to exert a pull on the first magnet.

Description

Technical area

The invention relates to the field of weaving looms, and more particularly to weaving looms whose insertion of the weft thread is ensured by pliers. It aims more precisely an improvement of the clamps in the mechanism of the exchange of the wire.

Previous techniques

In known manner, in a pliers loom, the device for the insertion of the thread weft consists essentially of two clamps, respectively of supply and exit, moving in alternating movements from both sides of the fabric penetrating substantially the same distance into the crowd to an exchange zone.

The clamps run through the crowd by sliding on a solid breakdown of the leaf, the feed clamp exerting a clamping force on the weft thread which can cause it to the exchange zone, and the output clamp exerting a clamping force on the wire weft to bring it back to the opposite edge of the fabric.

As is known, the looms and pliers are divided into two families differentiating by the operation at the time of the exchange of the wire.

Thus, in the so-called "positive" clamps, as described in the documents EP-A-0 690 160, GB-A-2 059 455 or DE-U-298 08 997, the inlet and outlet clamps are equipped with mechanisms acting when the clamps reach the exchange zone some thread. The mechanism on the feed clamp opens as soon as the mechanism of the output clamp pinched the weft thread when closing. In this way, the weft thread is always held during its transfer from one clamp to another. The order of these different mechanisms are carried out mechanically, by means of cams, or else electromechanically, through the use of electromagnets. We understand that the need to control the complex movements of the mechanisms present on the so-called clamps "positive" slows the maximum weaving rates.

We also know the family of trades known as "negative" pliers, mechanically simpler, in which the gripper exerts a force of pinching on the weft thread to drive it to the exchange area, while the clamp output is configured so that it pulls the wire out of the supply clamp and exerts a clamping force on the weft thread to drive it to the opposite edge of the fabric.

More precisely, this frame is generally held by the ends of the clamp supply system forming a lever and spring system.

The weft is brought to the center of the fabric to be transferred to the output clamp. The outlet clamp has a hook shape, and tears off the frame of the clamp in its return movement. This weft is held in the hook of the clamp exit by a lever system and spring corners. Compared to the system said to "positive clamps", the negative clamp device has the advantage of having more regular movements without the need for accompanying the clamps in the center of the machine to carry out the "positive" transfer of the frame.

On the other hand, with "negative" clamps, the transfer from one clamp to the other is done by tearing of the weft wire from the feed clamp by the outlet clamp, which prevents the use of this technique for irregular threads such as fancy threads, because stresses exerted on the wire.

The problem which the invention proposes to solve is that of combining both the speed of execution and simplicity of movement of the "negative" pliers, with the great versatility and adaptability to a wide variety of "positive" clamp wires.

Statement of the invention

The invention therefore relates to a device for the insertion of the weft thread, usable on the looms with pliers, the pliers respectively of infeed and out moving in alternating movements from both sides of the fabric as it enters substantially the same distance in the crowd to an exchange area, said clamps traversing the crowd by sliding on a solid failure of the leaf, the clamp being able to exert a pinching force on the weft thread to drive it up to the exchange zone, the outlet clamp being able to exert a clamping force on the weft thread to tear it off with the feed clamp, at the level of the exchange zone.

• des moyens pour diminuer la force de pinçage de la pince d'amenée, lorsque ladite pince d'amenée arrive à proximité de la zone d'échange ;
• des moyens pour augmenter la force de pinçage de la pince de sortie, lorsque ladite pince de sortie arrive à proximité de la zone d'échange.

The device is characterized in that it also includes:

• means for decreasing the clamping force of the supply clamp, when said supply clamp arrives near the exchange zone;
• means for increasing the clamping force of the outlet clamp, when said outlet clamp arrives near the exchange zone.

In other words, the invention consists in facilitating the transfer of the weft yarn from a clamp to the other by releasing the holding force of the wire in the feed clamp when this reaches the exchange zone, and concomitantly to accentuate the grip of the wire by the exit place when the latter tears off the weft thread at the supply place.

In this way, the movement of the clamps remains relatively rapid as with so-called "negative" pliers. We assist the clamping members of the pliers to allow the passage of irregular threads like fancy threads.

Obviously, in a minimal version, we can provide that only the clamp supply is equipped with means according to the invention, or conversely, only the clamp output provides assistance when pulling the wire.

• un élément aimanté disposé sur le battant, au niveau de la zone d'échange ;
• un élément de la pince d'amenée, apte à se déplacer sous l'effet du champ magnétique engendré par ledit élément aimanté disposé sur le battant ;
• un élément de la pince de sortie, apte à se déplacer sous l'effet du champ magnétique engendré par ledit élément disposé sur le battant.

In practice, the means for reducing the clamping force consist of:

• a magnetic element disposed on the leaf, at the level of the exchange zone;
• an element of the supply clamp, able to move under the effect of the magnetic field generated by said magnetic element disposed on the leaf;
• an element of the output clamp, able to move under the effect of the magnetic field generated by said element disposed on the leaf.

In other words, the decrease and / or increase in the clamping force is controlled by the passage of the clamps over the exchange zone, without any contact mechanical, but magnetically. This avoids any problem of wear by the contact of control parts.

It also avoids the introduction of mechanical parts through the web of son chain.

In practice, the magnetic element placed on the leaf can act either on pieces in ferromagnetic material, either on parts themselves magnetized.

Thus, in a first embodiment, the element of the supply clamp capable of move is a piece of ferro-magnetic material located on the area of the clamp of supply opposite the leaf, to form one of the pinching members proper, and mounted on said zone by means of a compression spring.

In other words, the active part of the clamp forming the nip area properly said, comprises two bodies facing each other. The one of these organs located the most near the leaf is spring loaded so as to be pressed against the opposite member when the gripper travels its main path.

On the other hand, as soon as the clamp reaches the right of the magnet located on the leaf, this organ is drawn towards the leaf and compresses the spring, thereby reducing the force of pinching the wire.

The reverse arrangement can be adopted on the output clamp in which the element able to move is located on the area of the clamp opposite the leaf and mounted on said area via a spring.

In another embodiment, the element of the supply clamp capable of moving is a magnetized part, located on the area of the clamp opposite the leaf, to form a pinching members proper, said magnetic part being arranged in such a way so that the faces of the magnetic element integral with the leaf and said part coming to look at each other have opposite magnetic polarities.

In this way, when the supply clamp comes in line with the integral magnetic element of the leaf, the magnetic element of the clamp is pulled downwards, thus relieving the frame.

Conversely, with regard to the output clamp, the element capable of moving can be a magnetized part located on the zone of the exit clamp opposite the leaf, to form a pinching members proper, said magnetic part being arranged in such a way so that the faces of the magnetic element integral with the leaf and said part coming to look at each other have identical polarities.

In an alternative embodiment, the supply clamp comprises a second part magnetized forming with the first magnetized part the pinching zone proper, and whose magnetic polarity is oriented so as to attract said first part.

In this way, the clamping force is ensured, outside the exchange zone, by the attraction between the two magnetized pieces of the clamp.

The same arrangement can be adapted on the output clamp.

Brief description of the figures

La figure 1 est une vue de côté d'une pince d'amenée réalisée selon un premier mode de réalisation.

La figure 2 est une vue de côté de la pince de sortie réalisée sur le même principe que celui de la figure 1.

La figure 3 est une vue de côté d'une pince d'amenée fonctionnant selon un second mode de réalisation.

La figure 4 est une vue de côté d'une pince de sortie fonctionnant sur le même mode de réalisation.

Les figures 5a à 5f sont des vues de côté de la zone d'échange du fil de trame, correspondant à différents stades des mouvements des pinces d'amenée et de sortie au fur et à mesure de la progression du transfert du fil, et selon une première forme de réalisation.

Les figures 6a à 6f correspondent aux figures 5a à 5f pour une seconde manière de réaliser l'invention. A l'intérieur de chaque jeu, les figures sont disposées les unes au-dessous des autres pour faciliter la visualisation de la progression des différentes pinces.

The manner of carrying out the invention and its advantages which result therefrom will emerge clearly from the description of the embodiments which follow, with the support of the appended figures in which:

Figure 1 is a side view of a feed clamp made according to a first embodiment.

FIG. 2 is a side view of the outlet clamp produced on the same principle as that of FIG. 1.

Figure 3 is a side view of a feed clamp operating according to a second embodiment.

Figure 4 is a side view of an output clamp operating on the same embodiment.

FIGS. 5a to 5f are side views of the weft thread exchange zone, corresponding to different stages of the movements of the feed and output grippers as the wire transfer progresses, and according to a first embodiment.

Figures 6a to 6f correspond to Figures 5a to 5f for a second way of carrying out the invention. Inside each set, the figures are arranged one below the other to facilitate the visualization of the progress of the different clamps.

Ways to realize the invention

As already said, the invention consists in equipping the so-called "negative" clamps with mechanisms that both relieve the pinching of the wire on the feed clamp, and to accentuate the pinching by the output clamp, at the time of the transfer by tearing.

The mechanisms work thanks to the action of a permanent magnet located on the beating at the level of the exchange zone, and acting on the mechanisms present at the level clamps, made either by ferromagnetic parts, or by parts themselves magnetized.

First way of carrying out the invention

As seen in Figure 1, the feed clamp (1), and more precisely its end has an opening (2) oriented towards the front, that is to say in the direction of progression of the lance during the introduction of the weft thread.

This opening (2) comprises a pinching zone (3) constituted by two surfaces (4, 5), coming towards each other to form a narrow clearance (6) inside which wedges the weft thread.

According to a first embodiment of the invention, the clamp comprises in its part (8) intended to come into view with the leaf, a movable part (9) mounted slidingly in a housing (10). This part is made of a ferromagnetic material, by example a steel with a high carbon content.

Between the part (9) and the bottom of the housing (6) is interposed a working spring (11) in compression, that is to say pushing at rest the part (9) outside the housing (10), in the direction of the face (4) forming the opposite face of the nip (3).

The outlet clamp (20) illustrated in FIG. 2 has an opening (22) directed towards the rear of the lance, so as to form a hook to tear off the wire weft (15) to the gripper.

This opening (22) has a nip (23) formed by two surfaces (24, 25) forming a game (26) of small dimension, able to wedge the weft thread (15).

According to the invention, the part (28) of the hook-shaped pliers, and remote of the leaf, comprises a housing (30) inside which is mounted to slide freely a piece (29) of ferromagnetic material.

The bottom of the housing (30) comprises a spring (31) working in compression, that is to say grouping the part (29) towards the outside of the housing (30).

The operation of the invention is illustrated in Figures 5a to 5f. So in the figure 5a, the feed clamp (1) and the outlet clamp (20) both move in direction of the exchange zone (16).

This exchange zone (16) has a magnet at the flap, not shown. permanent (17) whose magnetization is oriented towards the path of the clamps (1, 20).

Thus, before arriving at the exchange zone (16), the movable element (9) of the clamp feed (1) is pushed towards the nip (3) to trap the wire (15) against the opposite surface (4), the spring (11) therefore effectively clamps the wire (15). On the output clamp (20), the moving part (29) is pushed back towards the nip (23) by the spring (31).

Thereafter, the output clamp (20) as illustrated in FIG. 5b, progresses and exceeds the exchange zone (16), the state of the supply clamp (1) not being modified.

As seen next in Figure 5c, the supply and output clamps (1, 20) are cross, downstream of the exchange zone (16).

As seen in Figure 5d, when the feed clamp has passed the end before the exit clamp (20), the exit clamp initiates the recoil movement. The two clamps are at this point in relation to the permanent magnet (17) carried by the beating. The action of this magnet (17) modifies the configuration of the supply clamp (1) and the output clamp (20).

For the feed clamp (1), the permanent magnet (17) acts on the part (9) by attracting it towards the bottom of the housing (10), thereby relieving the pinching force exerted on the weft thread (15). The compression spring (11) can therefore be seen a little more compressed.

For the exit clamp (20), the permanent magnet (17) carried by the leaf attracts the moving part (29) which moves downwards towards the leaf to decrease the opening of the nip, and therefore increase the nip force wire (15) exerted by the output clamp (20).

Thus, the passage or transfer of the wire from the feed clamp to the outlet clamp is highly secure, which makes it possible to use fancy weft threads relatively irregular.

Subsequently, as seen in FIG. 5e, the feed clamp starts its backward movement to withdraw from the exchange zone (16). As long as the output clamp (20) is facing the magnet (17), the weft thread (15) is strongly pinched to ensure good lifting.

Then the movement ends while the clamps are no longer under the effect of the permanent magnet (17), as illustrated in FIG. 5f, the movable part (9) of the clamp supply (1) returning to its rest position, in contact with the surface (4) forming the face opposite the pinch area (3). As for the output clamp (20), the part mobile (29) is no longer subjected to the action of the magnet (17) and retracts slightly in its housing (30).

Second way of carrying out the invention

According to a variant illustrated in Figure 3, the feed clamp (41), which has also a forward-facing opening (42) is provided at the level of the pinching (43) of two permanent magnets (47) and (49). The element (49) located on the part (48) of the clamp coming in front of the leaf is mounted free sliding in a housing (50).

The feed clamp (41) also includes another magnetic (47) and fixed element. located in the part of the clamp opposite the leaf.

The polarities of the elements (47) and (49) are oriented in such a way that these the latter attract each other, to ensure an effective pinching of the weft thread when it found in the pinch area (43). Thus, the mutual attraction of the two magnets (47) and (49) plays the role of the compression spring (11) of the variant illustrated in FIG. 1.

The outlet clamp (60) illustrated in FIG. 4 also includes elements magnetized referenced (69) and (67). The magnetic element (69) is mounted to slide freely in a housing (70) formed on the part of the outlet clamp (60) which comes opposite of the clapper. The element (67) is fixedly mounted inside the part forming the hook (68) of the output clamp (60). The magnetic polarities of the magnetized elements (69), (67) are chosen and arranged in such a way that these two elements (67) and (69) attract each other, for pinch the weft thread (15).

The operation of the device according to this alternative embodiment is illustrated in Figures 6a to 6f. Thus, before arriving in the exchange zone (16), the magnetic element mobile (49) of the supply clamp (41) is attracted by the opposite element (47) ensuring thereby pinching the weft thread (15) inside the pinch area (43). On the output clamp (60), the magnetic elements (67, 69) also attract each other.

In the example illustrated, the element (49) of the supply clamp (41) has a pole North towards the pinch zone, the opposite element (47) directing its South pole towards the pinch area (43). Element (49) therefore has the South pole directed towards the beating. The permanent magnet (17) present on the leaf presents its North pole towards outlet and supply clamps.

On the output clamp, the polarities are distributed inversely, i.e. that the element (69) has its North pole directed towards the leaf, while its South pole is oriented towards the pinch zone opposite the North pole of the element (67).

In FIG. 6b, in the same manner as already described in FIG. 5b, the outlet clamp, during its movement, exceeds the exchange zone (16). When, as illustrated in Figure 6c, the feed clamp (41) continues its movement towards the area exchange (16), the weft thread passes over the part (68) forming a hook.

As illustrated in Figure 6d, the exit clamp then begins its movement set back, the two inlet and outlet clamps therefore being in the exchange zone, subjected to the effects of the permanent magnet (17).

More specifically, the permanent magnet (17) acts on the supply clamp (41) by attracting downwards, at the bottom of the housing (50) the moving magnetic part (49), the polarities in look of the magnets (47, 49) being opposite. It follows that the pinching force of the wire weft is slightly loosened at the feed gripper. On the output clamp (60), the element (69) is repelled by the permanent magnet (17), the polarities opposite these two elements being identical. It follows that the element (69) is pushed back towards from outside the housing (70), and compresses the wire (15) against the element (67) mounted on the hook (68).

Thus, the wire is more strongly pinched by the output clamp (60) at the time of uprooting.

Thereafter, as illustrated in FIG. 6f, the two clamps leave the exchange zone, and the element (49) of the supply clamp (41) returns to its position, in contact with the element (47) which attracts him.

For the output clamp (60), the additional gripping force caused by the repulsion of the magnetic element (69) by the magnet (17) disappears. The pinch force of the weft thread (15) is ensured by the single attraction of the magnetic elements (67) and (69).

Of course, the invention covers the variants in which the two modes of embodiment of Figures 1 and 4 are mixed, in which one of the clamps has a mobile ferromagnetic element, while the other has a magnetic element.

The invention also covers the variants in which only one of the pliers is equipped, in accordance with the invention, although the tearing-off occurs in this case of less secure way.

The invention also covers the variants in which the permanent element located on the leaf consists of one or more electromagnets controlled so suitable for presenting desired polarities.

It appears from the above that the weft insertion device conforms to the invention has the advantage of being usable for fancy weft threads, relatively irregular, while retaining the rates of negative clamps, and without require additional complex mechanical parts which are sources of friction and of wear.

Claims (8)

Device for the insertion of the weft thread, usable on the looms with pliers, the pliers respectively of supply (1, 41) and output (20, 60) moving by reciprocating movements from the two sides of the fabric by penetrating substantially the same distance into the crowd to an exchange zone (16), said clamps traversing the crowd by sliding on a failure integral with the leaf, the supply clamp (1, 41) being able to exert a gripping force on the weft thread (15) to drive it to the exchange zone (16), the outlet clamp (20, 60) being able to exert a gripping force on the weft thread (15) to tear it off with the feed clamp (1, 41), at the level of the exchange zone (16),
characterized in that it also includes: means for decreasing the clamping force of the supply clamp (1, 41), when said supply clamp (1, 41) arrives near the exchange zone (16); means for increasing the clamping force of the outlet clamp (20, 60), when said outlet clamp (20, 60) comes close to the exchange zone (16). Device according to claim 1, characterized in that the means for decreasing the clamping force of the supply clamp (1, 41) and for increasing the clamping force of the outlet clamp (20, 60) consist of: a magnetic element (17) disposed on the leaf, at the level of the exchange zone (16); an element (9, 49) of the supply clamp (1, 41), able to move under the effect of the magnetic field generated by said magnetic element (17) disposed on the leaf; an element (29, 69) of the output clamp (20, 60), able to move under the effect of the magnetic field generated by said magnetic element (17) disposed on the leaf. Device according to claim 2, characterized in that the element (9) of the feed clamp (1) capable of moving is a piece of ferromagnetic material located on the area (8) of the feed clamp ( 1) opposite the leaf, to form one of the pinching members proper, and mounted on said zone (8) by means of a compression spring (11). Device according to claim 2, characterized in that the element (29) of the clamp (20) capable of moving is a piece of ferromagnetic material located on the zone (28) of the clamp opposite the leaf, for forming the pinching members proper, and mounted on said zone by means of a compression spring (31). Device according to claim 2, characterized in that the element of the supply clamp (20) able to move is a magnetic part (49) located on the zone (48) of the clamp opposite the leaf, to form one of the pinching members proper, said magnetic piece (49) being arranged so that the faces of the magnetic element (17) integral with the leaf and said piece (49) coming towards each other have opposite magnetic polarities. Device according to claim 2, characterized in that the element of the exit clamp (60) able to move is a magnetic piece (69), located on the area of the exit clamp opposite the leaf, to form one of the nipping members proper, said magnetic piece (69) being arranged so that the faces of the magnetic element (17) integral with the leaf and said piece (69) coming towards each other have identical polarities. Device according to claim 5, characterized in that the supply clamp (41) comprises a second magnetized part (47) forming with the first magnetized part (49) the nip area proper, and whose magnetic polarity is oriented so as to attract said first part (49). Device according to claim 6, characterized in that the element of the output clamp (60) comprises a second magnetized part (67) forming with the first magnetized part (69) the nip zone proper, and whose magnetic polarity is oriented so as to attract said first part (69).

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