FR2783842A1 - DEVICE FOR INSERTING THE WEFT YARN - Google Patents

Abstract

1 / Device for inserting the weft thread, usable on pincer looms, the feed (1, 41) and exit (20, 60) clamps respectively moving in reciprocating movements from both sides fabric by penetrating substantially the same distance into the shed as far as an exchange zone (16), said clamps running through the shed by sliding on a purlin integral with the leaf, the feed clamp (1, 41) being suitable in exerting a clamping force on the weft thread (15) to drive it to the exchange zone (16), the output clamp (20, 60) being able to exert a clamping force on the thread weft (15) to tear it off from the feed clamp (1, 41), at the exchange zone (16), characterized in that it also comprises: - means for reducing the force of clamping of the feed clamp (1, 41), when said feed clamp (1, 41) comes close to the exchange zone (16); - means for increasing the clamping force of the clamp sor tie (20, 60), when said output clamp (20, 60) arrives near the exchange zone (16).

Description

DEVICE FOR INSERTING THE WEFT YARN

  Technical Field The invention relates to the field of weaving looms, and more particularly weaving looms, the insertion of the weft thread of which is ensured by pliers. More specifically, it aims to improve the clamps in the mechanism of

wire exchange.

  PRIOR ART In a known manner, in a pliers weaving machine, the device for the insertion of the weft thread essentially consists of two pliers, respectively of supply and output, moving in alternating movements from the two sides of the fabric by penetrating substantially the same distance into the crowd to an exchange zone. 15 The clamps run through the crowd by sliding on a failure integral with the leaf, the feeding clamp exerting a clamping force on the weft thread able to carry it to the exchange zone, and the output clamp exerting a clamping force on the weft thread to bring it back to the opposite edge of the fabric.

  As is known, the weaving and pliers looms are divided into two families which differ in terms of operation when the thread is exchanged.

  Thus, in the so-called "positive" pliers, the supply and output pliers are equipped with mechanisms acting when the pliers reach the wire exchange zone. The mechanism on the feed gripper opens as soon as the mechanism of the output gripper has pinched the weft thread by closing. In this way, the weft thread is always held when it is transferred from one clamp to another. The control of these various mechanisms is carried out mechanically, by means of cams, or else electromechanically, thanks to the use of electromagnets. We understand that the need to control the complex movements of

  mechanisms present on the so-called "positive" pliers slow the maximum weaving rates.

  We also know the family of trades known as "negative" pliers, mechanically simpler, in which the supply clamp exerts a force

  pinch on the weft thread to drive it to the exchange zone, while the output clamp is configured so that it pulls the thread from the feed clamp 5 and exerts a clamping force on the weft thread to drag it to the opposite edge of the fabric.

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

  The weft is brought to the center of the fabric to be transferred to the output clamp. The output clamp has a hook shape, and tears off the frame of the feed clamp in its return movement. This frame is held in the hook of the output clamp by a lever system and spring corners. Compared with the so-called "positive clamp" system, the negative clamp device has the advantage of having more regular movements without requiring

  accompanying the pliers in the center of the machine to carry out the "positive" transfer of the weft.

  On the other hand, with "negative" grippers, the transfer from one gripper to the other is done by tearing off the weft thread from the supply gripper by the output gripper, which

  prohibits the use of this technique for irregular threads such as fancy threads.

  The problem which the invention proposes to solve is that of combining both the speed of execution and the simplicity of movement of the "negative" pliers,

  with great versatility and the ability to adapt to a wide variety of "positive" clamp wires.

  SUMMARY OF THE INVENTION The invention therefore relates to a device for the insertion of the weft thread, usable on pliers weaving looms, the pliers respectively of supply and output moving by reciprocating movements from the two sides of the fabric by penetrating substantially the same distance into the crowd to an exchange zone, said clamps traversing the crowd by sliding on a fault integral with the leaf, the feeding clamp being able to exert a gripping force on 3 the weft thread to lead it to the exchange zone, the output clamp being

  able to exert a gripping force on the weft thread to tear it off with the feed clamp, at the level of the exchange zone.

  The device is characterized in that it also comprises: - means for reducing the clamping force of the supply clamp, when said supply clamp arrives near the exchange zone; - Means for increasing the clamping force of the output clamp, when

  said outlet clamp arrives near the exchange zone.

  In other words, the invention consists in facilitating the transfer of the weft thread from one clamp to the other by releasing the holding force of the thread in the feed clamp.

  when the latter reaches the exchange zone, and concomitantly to accentuate the grip of the wire by the outlet place at the moment when the latter tears off the weft thread in the place of supply.

  In this way, the movement of the clamps remains relatively rapid as with so-called "negative" clamps. The gripping members of the clamps are assisted to allow the passage of irregular wires like fancy wires. 20 Obviously, in a minimal version, it can be provided that only the feeding clamp is equipped with the means in accordance with the invention, or that conversely,

  only the output clamp provides assistance during the pulling of the wire.

  In practice, the means for reducing the clamping force consist of: - a magnetic element placed 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 field

  magnetic generated by said element disposed on the leaf.

  In other words, the decrease and / or increase of the clamping force is controlled by the passage of the clamps over the exchange zone, without

  no mechanical contact, but magnetically. This avoids any wear problem by contacting control parts.

  The introduction of mechanical parts through the web of warp threads is also avoided.

  In practice, the magnetic element placed on the leaf can act either on parts made of ferromagnetic material, or on parts themselves magnetized. Thus, in a first embodiment, the element of the feeding clamp capable of moving is a piece of ferro-magnetic material located on the area

  of the feed clamp opposite the leaf, to form one of the clamping members proper, and mounted on said zone by means of a compression spring.

  In other words, the active part of the clamp forming the nipping zone proper, comprises two members facing each other. One of these

  organs located closest to the leaf is mounted on a spring so as to be pressed against the opposite organ when the clamp travels its main path.

  On the other hand, as soon as the clamp reaches the right of the magnet located on the leaf, this member is attracted in the direction of the leaf and compresses the spring, thus reducing

the pinching force of the wire.

  The reverse arrangement can be adopted on the outlet clamp in which the element capable of moving is located on the area of the clamp opposite the leaf and mounted on said area by means of a spring. 25 In another form embodiment, the element of the supply clamp capable of moving is a magnetic piece, located on the area of the clamp opposite the leaf, to form one of the clamping members proper, said magnetic piece being arranged in such a way that the faces of the magnetic element integral with the leaf

  and of said piece coming towards each other have opposite magnetic polarities.

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

so the weft thread.

  Conversely, with regard to the output clamp, the element capable of moving can be a magnetized part located on the zone of the output clamp opposite the leaf, to form one of the pinching members proper, said magnetized part being arranged so that the faces of the magnetic element integral with the leaf and said part coming opposite one another have identical polarities. In an alternative embodiment, the supply clamp comprises a second magnetized part 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 parts of the clamp.

  The same arrangement can be adapted on the output clamp.

Brief description of the figures

  The manner of carrying out the invention and its advantages which flow therefrom

  Will emerge clearly from the description of the embodiments which follow, in support of the appended figures in which:

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

  Figure 2 is a side view of the output clamp made on the same

principle as that of figure 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 game, the figures are 6 arranged one below the other to facilitate the visualization of the

  progression of the different clamps.

  Ways of realizing the invention As already said, the invention consists in equipping the so-called "negative" pliers with mechanisms making it possible both to relieve the pinching of the wire on the pliers

  and 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 leaf at the level of the exchange zone, and acting on the mechanisms present

  at the level of the clamps, produced either by ferromagnetic parts, or by parts themselves magnetized.

  First way of carrying out the invention As can be seen in FIG. 1, the feed clamp (1), and more precisely its end has an opening (2) oriented towards the front, that is to say in meaning

  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) to

  inside which the weft thread gets stuck.

  According to a first embodiment of the invention, the clamp comprises in its part (8) intended to come opposite the leaf, a movable part (9) slidably mounted in a housing (10). This piece is made of a material

  ferromagnetic, for example a steel with a high carbon content.

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

pinching (3).

  The output clamp (20) illustrated in Figure 2 has a

  opening (22) directed towards the rear of the lance, so as to form a hook for tearing off the weft thread (15) from the feed clamp.

  This opening (22) comprises a nip (23) formed by two surfaces (24, 25) forming a game (26) of small size, capable of wedging the wire.

weft (15).

  According to the invention, the part (28) of the hook-shaped pliers, and

  remote from the leaf, comprises a housing (30) inside which is freely slidably mounted a piece (29) of ferromagnetic material.

  The bottom of the housing (30) has 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. Thus, in FIG. Sa, the supply clamp (1) and the outlet clamp (20) both move in the direction of the exchange zone (16) .15 This exchange zone (16) has at the wing not shown a permanent magnet (17) whose magnetization is oriented in the direction of the trajectory

clamps (1, 20).

  Thus, before arriving at the exchange zone (16), the movable element (9) of the supply clamp (1) is pushed back towards the pinch zone (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) .25

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

  As seen next in Figure 5c, the supply and output clamps

  (1, 20) intersect, downstream of the exchange zone (16).

  As seen in Figure 5d, when the feed clamp has passed the front end of the outlet clamp (20), the outlet clamp initiates the movement

  step back. The two clamps are at this point facing the permanent magnet35 (17) carried by the leaf. The action of this magnet (17) modifies the configuration of the supply clamp (1) and the outlet 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), and thus relieving the pinching force exerted on the wire weft (15). The compression spring (11) is therefore seen to be a little more compressed. 5 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 reduce the opening of the pinch zone, and therefore increase the pinching force of the wire (15) exerted by the output clamp (20) .10 Thus, the passage or transfer of the wire from the supply clamp to the output clamp is highly secure, which allows the use of fancy weft threads

relatively irregular.

  Subsequently, as seen in Figure Se, the feed clamp begins its recoil movement to withdraw from the exchange zone (16). As long as the clamp

  outlet (20) is facing the magnet (17), the weft thread (15) is strongly pinched to ensure good tearing.

  Then, the movement ends while the clamps are no longer under the effect of the permanent magnet (17), as illustrated in Figure 5f, the movable part (9) of the

  feed clamp (1) returning to its rest position, in contact with the surface (4) forming the opposite face of the clamping area (3). With regard to the output clamp (20), the movable part (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 FIG. 3, the feed clamp (41), which also has an opening (42) oriented towards the front, is equipped, at the level of the nip (43 ) 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 to slide freely

in a housing (50).

  The feed clamp (41) also includes another magnetic element (47) and

  fixed 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 the latter attract each other, to ensure an effective clamping of the weft thread when this one

  this is 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 variant 5 illustrated in FIG. 1.

  The output clamp (60) illustrated in FIG. 4 also includes magnetic elements referenced (69) and (67). The magnetic element (69) is freely slidably mounted in a housing (70) formed on the part of the outlet clamp (60) which comes opposite the leaf. The element (67) is fixedly mounted inside the hook forming part (68) of the outlet 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, to ensure a pinching of the weft thread (15) .15 Operation of the device according to this variant embodiment is illustrated in FIGS. 6a to 6f. Thus, before arriving in the exchange zone (16), the mobile magnetic element (49) of the supply clamp (41) is attracted by the opposite element (47) thereby ensuring the pinching of the weft thread (15) inside the area

  pinch (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 North pole in the direction of the nip, the opposite element (47) directing its South pole towards the nip ( 43). The element (49) therefore has the South pole directed towards the leaf. The permanent magnet (17) on the leaf has

  its North pole towards the exit and supply clamps.

  On the output clamp, the polarities are distributed inversely, i.e.

  say that the element (69) has its North pole directed in the direction of 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, like

  illustrated in FIG. 6c, the feed clamp (41) continues its movement towards the exchange zone (16), the weft thread passes over the part (68) forming a hook.

  As illustrated in FIG. 6d, the outlet clamp subsequently initiates its recoil movement, the two inlet and outlet clamps therefore being found in the exchange zone, subjected to the effects of the permanent magnet (17) .10 More specifically, the permanent magnet (17) acts on the supply clamp (41) by attracting downwards, at the bottom of the housing (50) the magnetized moving part (49), the polarities facing the magnets ( 47, 49) being opposed. It follows that the gripping force of the weft thread is slightly released at the feed clamp. On the outlet clamp (60), the element (69) is pushed back by the permanent magnet (17), the opposite polarities of these two elements being identical. It follows that the element (69) is pushed back towards the outside of 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 outlet clamp (60) at the time of tearing.

  Subsequently, 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, at

  contact of the element (47) which attracts it.

  For the output clamp (60), the additional gripping force caused by the repulsion of the magnetic element (69) by the magnet (17) disappears. The strength of

  pinching of the weft thread (15) is ensured by the sole attraction of the magnetic elements (67) and (69).

  Of course, the invention covers the variants in which the two embodiments of FIGS. 1 and 4 are mixed, in which one of the clamps

  have a movable ferromagnetic element, while the other has a magnetic element.

  It The invention also covers the variants in which only one of the clamps is equipped, in accordance with the invention, although tearing occurs

  in this case less securely.

  The invention also covers the variants in which the permanent element located on the leaf consists of one or more electromagnets

  appropriately controlled to exhibit desired polarities.

  It appears from the above that the weft insertion device according to the invention has the advantage of being usable for fancy weft threads, relatively irregular, while retaining the rates of negative clamps, and

  without requiring additional complex mechanical parts, sources of friction and wear.

Claims (3)

  1 / 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 fault integral with the leaf, the feeding clamp (1, 41) being suitable exerting a gripping force on the weft thread (15) to drive it to the exchange zone (16), the outlet clamp (20,10 60) being able to exert a gripping force on the weft thread (15) to tear it off from the feed clamp (1, 41), at the level of the exchange zone (16), characterized in that it also comprises: - means for reducing the force pinching the feed clamp (1, 41), when said feed clamp (1, 41) comes close to the exchange zone (16);   - Means for increasing the clamping force of the outlet clamp (20, 60), when said outlet clamp (20, 60) arrives near the exchange zone (16). 2 / 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) are constituted by: - 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 beating.   3 / Device according to claim 2, characterized in that the element (9) of the supply clamp (1) able to move is a part made of a ferromagnetic material   located on the zone (8) of the supply 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).   i 1 4 / device according to claim 2, characterized in that the element (29) of the gripper (20) capable of moving is a piece of material   ferromagnetic located on the zone (28) of the clamp opposite the leaf, to form 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, for form one of the pinching members 10 proper, said magnetic part (49) being arranged so that the faces of the magnetic element (17) integral with the leaf and said part (49) coming   look at each other have opposite magnetic polarities.   6 / Device according to claim 2, characterized in that the element of the outlet clamp (60) able to move is a magnetic piece (69), located on the area of the outlet clamp opposite the leaf, to form one of the pinching members proper, said magnetic part (69) being arranged such that the faces of the magnetic element (17) integral with the leaf and said part (69) coming into view with one another have identical polarities. 20 7 / 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 pinching zone proper, and the magnetic polarity of which is oriented so as to attract said first part (49). 25 8 / 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 magnet piece ée (69) the nipping area proper, and whose magnetic polarity is oriented so as to attract said first part (69) .30