EP0119122B1 - Device for presenting the weft to the insertion needle of a loom, and loom provided therewith - Google Patents

Description

The invention relates to weaving machines and, in particular, a device for presenting a weft in front of a weft pass needle, a device which is located between a weft pass eyelet and the edge of the fabric.

The insertion of the weft into the crowd of certain weaving machines is carried out using two weft pass needles including an input needle and an output needle animated back and forth. reverse.

The input needle must grip the stored weft thread coming from a reserve located outside the machine. To pick up the weft by the weft pass, it is necessary to present it at a well-determined location corresponding to the pinch point of the weft pass.

Various methods are known for the presentation of a weft in front of a weft pass needle. In general, the weft is stretched between two gripping points, on the one hand closest to the width and on the other hand in a tensioner, the weft coming from a reel located outside the tensioner and the machine .

The first installation of the weft in the clamp is done manually before starting the machine. A clamp and wire cutter member oscillating on a horizontal axis carrying a clamp and a knife perpendicularly on this axis, is combined so as to pinch the weft firstly, to cut it once pinched. This organ is controlled at each cycle by the leaf.

Keeping the frame in place once cut is ensured by two cooperating parts of the device.

The frame is thus ready to be inserted. The advance movement transmitted to the weft pass needle allows the latter, by means of its clamp, to take the weft on the way to insert it into the crowd and to transfer it to the opposite needle, the weft-passing needle returning to the starting point cleared of the weft.

After the weft-passing needle comes out of the width, the pliers and thread cutters open like scissors. This organ is controlled by the wing. Meanwhile, the weft has slipped into a beak of the pliers and wire cutters, the assembly is closed, the weft is folded down, pinched and cut. The cycle can start again.

The known weft presentation assembly which has just been described has certain drawbacks, especially for the fast looms.

The clip and wire cutter member is mounted on the leaf and follows its movement; a fixed ramp fixed to the machine frame controls the opening and closing of the pliers and the wire cutter. This maneuver is carried out near the neutral point before, after the exit and before the entry of the weft-passing needle into the width.

The inertia transmitted by speed to the pliers and wire cutters tends to bounce this member. despite a brake provided on the control axis of the pliers and the knife. Excessive braking leads to rapid wear of the control elements.

Another risk exists: for reasons of convenience, the operator can actuate the pliers and wire cutters manually; a forgetting to close on his part leads to significant material damage.

To avoid the drawbacks of the frame presentation assemblies, of the type described above, whose members are carried and controlled by the leaf, we have proposed devices entirely carried by the fixed frame of the loom and whose movable members are positively actuated by cams rotating in synchronism with the main loom of the loom.

This is how, in French patent 1 394 396, a device for presenting a weft in front of a weaving loom needle is described which comprises a folding mechanism 24 and a presentation mechanism 20 in front of the needle 10 of the portion of the weft included between a thread guide and the edge of the fabric, and which also comprises a mechanism 130 for cutting the end of the weft located near the edge of the fabric, each of said mechanisms being carried by a fixed part of the frame of the loom to be woven and being actuated individually by a cam 34, 36 rotating in synchronism with the main shaft of the loom.

The present invention relates to a presentation device of this known type, the definition of which is given in the preamble to claim 1 attached.

It appeared that such a known device, if it was suitable for the looms used until a few years ago and having rates of 200 to 250 strokes / minute, could no longer keep up with the rate of modern fast looms which reaches 450 to 500 shots / mirrute. Indeed, at such rates, the weft thread did not penetrate sufficiently between the branches of the head of the weft pass needle to be gripped securely by the needle, which gave rise to weft defects.

On the other hand, some of the moving parts, in particular the folding mechanism, required a large stroke incompatible with the high rates.

The present invention aims to remedy these drawbacks.

The presentation device according to the invention is characterized: in that it comprises a fixed gripping mechanism of the weft, carried by the frame of the loom, facilitating the gripping of the weft by the needle; and in that the folding mechanism comprises a folding finger which is slidably mounted vertically in a movable guide in rotation carried by the frame of the loom and which is provided with a folding spout and comprises a linkage link interposed between said finger and the cam surface of the cam.

Thanks to the invention, the pinching force of the fixed pinch mechanism helps the weft to penetrate without fail between the twig and the body of the weft feeder, after the weft is presented facing the needle. In addition, the spout carried by the folding mechanism describes, at the folding, a curvilinear movement both down and towards the front of the loom, which provides a safe positioning of the weft thread, even at high speeds of career.

Various other features of the invention appear in the following description and in the appended claims.

• La figure 1 représente une vue schématique de l'ensemble de présentation de trame.
• La figure 2 montre le doigt de rabattage de la trame et sa commande.
• La figure 3 montre le crochet de mise en place de la trame dans la pince et dans l'encoche de la contre-lame du coupe-fil.
• La figure 4 montre l'ensemble coupe-fil et sa commande.

The invention is set out below in more detail, with the aid of drawings representing all of the various organs making up the device for the presentation of the weft in front of a weft pass needle.

• Figure 1 shows a schematic view of the frame presentation assembly.
• Figure 2 shows the weft folding finger and its control.
• Figure 3 shows the weft positioning hook in the clamp and in the notch of the thread cutter counterblade.
• Figure 4 shows the wire cutter assembly and its control.

The presentation device will be described according to the order of entry according to the different organs allowing the setting up of the frame.

As described above, the weft T is kept tensioned between two pinching points by the fabric a) on the one hand and by a tensioner b) on the other hand, the weft coming from the reel O) which is located outside b). Next to the tensioner b) and between the width a), a fixed eyelet d) in the case of monoframe or an eyelet d) mobile in the case of a weft mixer positions the weft always in the same place, as it is classic.

The device according to the invention is located on the edge of the loom, between the fabric a) and the eyelet, fixed or mobile, d.

On the passage of the frame T is a folding finger 1 which is controlled by means of a concave cam 2 and of a lever 3 which is mounted oscillating by its end 3a on a pin 4 (Figures 1 and 2 ).

The lever 3 is provided with a roller 5 which is applied to the cam 2 under the action of a tension spring 6 attached to the lever 3 on one side and to the frame 7 of the loom on the other. The end 3b of the lever 3 carries a hinge 8 on which is mounted the lower part of the finger 1 for folding the weft. The finger 1 itself carries a slide 9 which engages on a rectangular guide 10, movable in rotation, which is held by an axis 11 secured to the frame. The folding finger 1 carries at the upper part a spout 12 located on the path of the frame. During the downward movement of finger 1, the spout 12 describes a slight movement towards the front of the machine (to the left in FIG. 2). The folding finger 1 is in action while the weft-passing needle is at rest outside the width. During insertion, the finger 1 is at rest, its beak 12 is positioned above the weft pass needle 13, in the position which is shown in FIG. 2.

The cam 2 is driven in rotation by a shaft 43 which rotates in synchronism with the main shaft (not shown) of the loom.

All the folding assembly R which has just been described is therefore carried by the frame of the machine, independently of the leaf, and it is actuated positively by the cam 2 and not by the movements of the leaf.

Following the sequence of folding down the weft which has just been described, a second member of the device, called "presentation hook 14 (Figures 1 and 3) comes into action. This hook is disposed below the level of the path of the weft-passing needle 13 and the weft which has been lowered by the folding-down finger 1 is then in front of the hook 14, at the level of the latter.

The curved end 14a of the hook 14 drives the lowered weft by turning around an axis 16. During rotation, the weft is slid into a fixed clamp 27 composed of a lower blade, in an arc, 28 and d 'an upper blade 29.

Since the weft lowering by the finger 1, it rests on the lower pinching blade 28 and is held in this position during its positioning in the clamp 27 by a trajectory of the hook 14a in an arc below the blade 28, combined with a movement from top to down obtained by the inclination of the control axis 16. At the end of the stroke, the hook 14, 14a is substantially perpendicular to the path of the pass needle -frame 13, as shown in broken lines in FIG. 1.

The hook 14 is also controlled by a convex cam 17. A lever 18 mounted on an axis 19 by its end 18a carries at its other end 18b an axis 20 provided with a roller 21 which rests on the cam 17. Between the ends 18a, 18b of the lever 18 is hooked a spring 22. L the other end of the spring 22 is fixed to the frame 7. Under the traction of the spring 22 and by means of the lever 18, the roller 21 is applied against the cam 17. A connecting rod 23 carrying at each end a ball joint 23a and 23b, is fixed at one end by the ball 23a on the lever 18 between 18a and 18b. The second end 23b is connected to a crank 24, itself fitted on the control shaft 16: an inclined bearing 25, which is integral with the frame 7, maintains the control shaft 16 in position. Said axis 16 is provided at its upper part with a nut 26 which is adjustable in rotation and longitudinally relative to the control axis 16. This nut 26 carries the hook 14 which is also adjustable in rotation.

The precise function of the hook 14 consists in taking the weft stretched on its passage and in guiding it in the clamp 27 composed of the two gripping blades, lower 28 and upper 29, the two blades having the shape of an arc of a circle to allow the hook 14 to bypass them and easily engage the frame. The weft T being held in the facade F of the fabric, the movement of the hook 14 guides it at the same time during its trajectory in a notch 40 belonging to the fixed knife 39 which will be described in the following.

The weft being in place in the clamp 27 and ready to be inserted, the weft needle begins its movement and takes the weft in passing, the clamp 27 by the gripping force helps the weft to penetrate between the twig and the body of the weft feeder, after placing the weft in the weft feeder needle: the weft is immediately cut by the knife, as will be seen below, and inserted into the shed by the needle 13.

The cam 17, which controls the back-and-forth movement of the presentation hook 14, is fixed on a shaft 43 'which rotates in synchronism with the main shaft of the loom.

It is clear from the foregoing that all the members of this second set P of the device, that is to say the set for presenting and gripping the frame, are supported by the frame of the loom and that the movable members are controlled positively (by cam 17), and not by the movements of the leaf.

We will now describe the third assembly C of the device, which is the frame cutting assembly and which is shown in detail in FIG. 4.

This assembly includes a movable knife 37 and a fixed counter blade 39 (Figures 1 and 4). The movable knife 37 is also controlled by a cam 30 like the two previous assemblies. A lever 31 supports at one end a roller 32. Said lever is mounted rotating on an axis 33 carried by the frame 7. Between the ends 31 a, 31 b of the lever 31 is fixed an axis 34 carrying an articulation 35 with two branches. On a branch 35a of said articulation is fixed a spring 36; the other end of the spring is hooked to the frame 7. The second branch 35b maintains the movable knife 37 by means of its rod 38. The fixed counter blade 39, provided with the notch 40 is fixed to the frame 7.

To achieve a good cut of the frame, the movable knife 37 is applied continuously against the fixed blade 39 by its oscillation joint 34 and by the action of the spring 36; the latter, by means of the articulation 35 of the axis 34 and of the lever 31 keeps the roller 32 on the path of the cam 30.

At rest, the movable knife 37 is in the low position (Figure 4). The frame retained in the notch 40 is cut between the upper edge of the notch and the cutting edge 41 of the movable knife 37 during the rise.

The weft being thus presented on the path of the needle 13 and cut is inserted into the crowd by the needle while the three assemblies which have just been described return to their rest positions shown in Figures 2, 3, 4 .

After the insertion needle has returned, the inserted weft is compacted by the comb, the end of the weft protruding from the edge of the fabric engaging and being retained in a fixed hook 42 (FIGS. 1 and. 4), secured to the machine frame, so that it is always kept in the same place after tamping.

All the members of the third assembly of the device (weft cutting assembly) are also carried by the frame 7, the movements of the movable knife 37 being positively controlled by the cam 30 which is wedged on a shaft 43 "rotating in synchronism with the main tree of the trade.

For clarity of the drawings and for simplification of the description, it has been assumed that the three cams 2, 17, 30 were independent, but it is quite obvious, since all these cams have their axes of rotation parallel, that, in practice , they are mounted side by side on a single common shaft, which rotates in synchronism with the main shaft of the loom, and which they successively come into action, by their hollows or by their hump, in the order: cam 2- cam 17-cam 30.

Thanks to the fact that all the movable members of the device according to the invention are positively controlled by cam and are carried by the frame of the loom, the operating faults encountered at high speeds are avoided with the known devices which were carried and / or controlled by the wing and which were subjected to harmful inertia forces. It was thus possible to increase the speed of the looms thus equipped.

The preferred embodiment of the invention has been indicated in the foregoing in which the three successive functions: folding down the weft; pinching and presentation; cutting of the frame, are carried out by means of three contiguous sets each having a single function.

According to an alternative embodiment, the first two functions can be carried out by a single assembly, namely that represented in FIG. 3. In this case, the curved part 14a of the hook 14 is extended by an ascending oblique part (substantially parallel to the upper layer S of the warp threads in FIG. 3) extending sufficiently upwards to hang the weft T (FIG. 1) which has not been, in this case, previously folded down. During the pivoting movement of the hook 14, the weft T slides along the oblique extension of the hook, which lowers it until it reaches the curved part 14a of the hook 14 which drives it in the clamp 27.

Since the weft is folded down by the hook 14, it is possible to remove the folding assembly shown in FIG. 2.

However, this variant does not make it possible to reach the highest speeds which are reached only when the weft folding assembly shown in FIG. 2 is present. Indeed, this mechanism, thanks to its individual cam control, can fold the weft much faster than the hook 14, in the variant which has just been described.

Claims (4)

1. A device for presenting the weft to the insertion needle of a loom which comprises a mechanism for casting off and presenting to the needle (13) the portion of the weft (T) between a guiding eyelet (d) and the edge (a) of the fabric, and which also comprises a cutting mechanism (C) of the end of the weft located close to the edge (a) of the fabric, each of said mechanisms being carried by a fixed part (7) of the frame of the loom and being activated separately by a cam (2-17-30) rotating in synchronism with the main shaft of the loom, said device being characterised in that it further comprises a fixed weft gripping mechanism (27) carried by the frame (7) of the loom, permitting gripping of the weft carried by the needle ; and in that the casting off mechanism (R) comprises a casting off finger (1) which is slidably mounted in a generally vertical direction in a rotating movable guide (10) carried by the frame (7) of the loom and which is provided with a casting off hook (12) and comprises a connecting linkage (3, 4, 8, 5) interposed between said finger (1) and the cam surface of the cam (2).

2. A device according to Claim 1, characterised in that the presenting mechanism comprises a presenting hook (14) which is carried by a shaft (16) pivotably mounted in a support (25) integral with the frame (7) of the loom and which is provided with a presenting hook (14a) ; in that the fixed weft gripping mechanism (27), which is carried by the frame (7) of the loom is constituted by two gripping blades, a lower blade (28) and an upper blade 29, in the form of an arc of a circle which extends over the arc of a circle trajectory of the hook 14 ; and in that a connecting linkage (18, 19, 21, 23, 24) is interposed between said shaft (16) and the cam surface of the cam (17).

3. A device as claimed in Claim 2, characterised in that the shaft (16) is inclined obliquely to the vertical.

4. A loom, characterised in that it is provided with a device for presenting the weft (T) to the insertion needle (13) according to any one of Claims 1 to 3, said device being carried by the frame (7) of the loom and being located on the side of the loom, between a weft guiding eyelet (d) and the edge (a) of the fabric.

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