Method to form a tucked-in selvedge in shuttleless, particularly air looms, and device to carry out said method

Abstract: Method and device to form a tucked-in selvedge in shuttleless looms, particularly air looms. Said selvedge is formed by sucking the cut weft tails into a suction and blowing nozzle (5, 9) and inserting them again into the newly opened shed by reversing the air stream inside said nozzle. The nozzle (5, 9) is positioned adjacent to the weft yarn (2) to be sucked, before this latter is cut and while the reed (4) is beating up the weft, and it remains in that position while the cutter (6, 10) is moved forward to the cutting point and the reed (4) is leaving the beating up position. In air looms, on the side of weft insertion, a fixed or movable screen (7, 8) - which may be rigidly connected to the nozzle (5) - deviates the air jet blown from the main yarn launching nozzles (1), which could disturb the weft tail sucking action into the nozzle (5). A V-shaped notching (7a, 8a) allows to house the weft yarn (2) into the screen (7, 8).

Description: The present invention concerns a method to form a tucked-in selvedge in shuttleless looms and, particularly, a method forming the tucked-in selvedge by exclusively pneumatic means allowing to fold back the weft tails into the shed. The present invention also concerns a device to form a tucked-in selvedge in shuttleless looms, particularly suited to allow carrying out said method. As known, in modern shuttleless looms the traditional selvedge is no longer formed seen that the weft yarn is not continuous but is cut after each weft insertion. The fabric thus ends laterally with a fringe of free wefts, sometimes only partially interwoven with a certain number of additional warp yarns, slightly set apart from the main warp yarns of the fabric so as to form what is technically defined as "split selvedge". This type of lateral finish of the fabric is acceptable in some cases, but it cannot generally be accepted for good quality fabrics which require the free ends of the weft yarns - normally called tails - to be more firmly fastened. This is obtained for example by inserting again the weft tails into the shed soon after the weft has been beaten up, and thus forming the so-called "tucked-in selvedge", which eliminates the need to fasten the selvedge of the fabric with the more complicated slotted leno heald weave, obtained by twisting the lateral warp yarns. To form the tucked-in selvedge, the tail of an inserted and beaten up weft must be at once folded back into the shed, as soon as the latter has opened again, so as to be newly beaten up therein and be fastened together with the following weft. In prior art, there are known to be several methods to form a tucked-in selvedge, both by mechanical and by pneumatic means, but - so far - none of them has proved fully satisfactory to obtain a perfect tucked-in selvedge - that is, of even width, strong enough not to fray, and showing no weaving defects - and to simultaneously allow working at a high speed. All the known devices are also quite complicated and not fully reliable. In particular, the known methods to form the tucked-in selvedge normally operate with fixed devices, positioned to the side of the beating up line, whereby, in order to operate on the weft delivery side, they require cutting of the reed, which means that the width of the reed has to be reduced to the actual width of the cloth being woven, when said width is below the maximum width of the loom. Reed cutting obviously involves the need for a long operation to readapt the reed, whenever starting to weave a new article. This is evidently quite disadvantageous from the economical point of view, both for the lack of productivity due to stopping of the loom, and because it requires the constant presence of skilled labour - difficult to find and to train, as well as involving high costs - but, above all, due to the high cost of the reed which, once it has been cut, can no longer be used to weave cloths of further width. An example of device to form a tucked-in selvedge according to the prior art is disclosed in FR-2141808. The present invention therefore proposes a method, as well as a device to carry out said method, allowing to form a high-quality tucked-in selvedge, while operating at high speed and merely with the use of pneumatic devices. Another object of the present invention is to supply a method and a device allowing to form the tucked-in selvedge, both on the weft feeding and on the weft delivery side, without having to in the least modify any of the loom components, and particularly the reed. A further object of the present invention is to supply a method and a device as specified heretofore, allowing to form a high-quality tucked-in selvedge both on air looms and on gripper looms. According to the present invention, said objects are reached with a method of the above described type, which comprises, in succession, the following steps to be carried out after closing of the shed and before a new weft insertion takes place: a) Approaching air suction means to the uncut weft yarn, while the reed is in a beating up position; b) Approaching cutting means to the weft yarn, as the reed is leaving the beating up position, while keeping the suction means adjacent to said weft yarn; c) Cutting the weft yarn with said cutting means, thus allowing the weft tail to be sucked into said air suction means; d) Moving the suction means to a zone facing the open shed, where the free weft tail is inserted again; and e) Reversing the air stream inside said suction means, so as to launch the weft tail into the shed. In air looms, on the side of weft insertion, the method comprises fixed cutting means, while step b) is replaced by the following step: b') Screening the air jet blown from the launching nozzles. Said method is preferably carried out with a device comprising air suction means and yarn cutting means, independently apt to perform cyclic movements between: a first position in which said air suction means are adjacent to the weft yarn and to the reed, and said yarn cutting means are in a rest position not interfering with the reed when this latter is beating up the weft yarn; a second position in which said cutting means are moved close to the weft yarn so as to cut the same, and said suction means remain in their previous position so as to suck in the free weft tail as the reed is leaving the beating up position; and a third position in which said suction means are at the side of the open shed so as to insert said weft tail, which is launched therein by reversing the air stream inside said suction means, while the reed is far from the beating up position. In air looms, on the side of weft insertion, said device comprises: fixed yarn cutting means; air suction means apt to perform a cyclic movement between a first position adjacent to the weft yarn as the same is being cut, so as to suck in the free weft tail, and a second position at the side of the open shed, so as to insert said weft tail which is launched therein by reversing the air stream inside said suction means, while the reed is far from the beating up position; and a screen interposed between said air suction means and the yarn launching nozzles, as the weft yarn is being cut, comprising means to house the weft yarn therein. The method according to the present invention will now be described in detail, with reference to some preferred embodiments of the device allowing to carry out the same, given by way of example and not limiting the invention itself. Said embodiments are illustrated on the accompanying drawings, in which: Figs. 1A and 1B are diagrammatic perspective views of the weft insertion side of an air loom, equipped with a first embodiment of the device to form the tucked-in selvedge according to the present invention, showing - respectively - the weft yarn launching and the yarn cutting steps. Figs. 2A and 2B are lateral views, on an enlarged scale, showing two different embodiments of one portion of the device illustrated in fig. 1; Fig. 3 is a diagrammatic perspective view of the weft insertion side of an air loom, equipped with a second embodiment of the device according to the present invention; Fig. 4 is a perspective view, on an enlarged scale, turned over by 180°, of the nozzle and screen illustrated in fig. 3; Figs. 5A, 5B and 5C are lateral views, on an enlarged scale, of the same device illustrated in fig. 3, showing - respectively - the weft yarn launching step, the reed beating up step, and the yarn cutting step; Fig. 6 is a diagrammatic perspective view of the weft delivery side of a shuttleless loom, equipped with the device to form the tucked-in selvedge according to the present invention; Fig. 7 is a plan view of the same side of the loom shown in fig. 6, illustrating the different steps to carry out the method according to the present invention; Fig. 8 is a lateral view of the same device shown in fig. 7, mounted on an air loom; Fig. 9 is a diagrammatic lateral view, on the weft delivery side of the loom, of a first embodiment of the device to form the tucked-in selvedge, adopting mechanical means; Figs. 10A and 10B are, respectively, a diagrammatic elevation view and a plan view, on the weft insertion side of the loom, of a second embodiment of the device to form the tucked-in selvedge, adopting pneumatic means; and Figs. 11A and 11B are, respectively, a diagrammatic elevation view and a plan view, on the weft delivery side of the loom, of the same embodiment of the device to form the tucked-in selvedge illustrated in fig. 10. In air looms - which form a large branch in the field of shuttleless looms, and for which the present invention was primarily conceived - different and non-symmetrical weaving situations arise on the two sides of the loom, respectively the weft insertion side and the weft delivery side (hereinafter simply called loom inlet and loom outlet), as opposed to what happens in the other large branch of shuttleless looms, namely gripper looms. For this reason, the method according to the present invention - in the case of air looms - comprises two different procedures and is carried out by different devices on either side of the loom. The following description will thus illustrate separately the method and the device of the invention in relation to these two different procedures, starting from loom inlet. It is understood that the embodiment subsequently described with reference to loom outlet, is also applicable - this time in a perfectly symmetrical way on both sides of the loom - in the case of gripper looms. As known, in air looms, weft insertion takes place by launching the weft yarn, by means of a main nozzle, into the shed formed by the opened-up warp yarns; the weft is fed through said nozzle from weft yarn feeding devices positioned upstream thereof. In case of weaving with more wefts, the main nozzle is formed by a set of pipes and takes up the configuration of a gun 1, as shown in fig. 1. While launching a weft yarn 2, the respective nozzle is fed with a high-pressure air stream, so as to launch said weft yarn into the launching channel 3, formed by suitable notchings provided in the central part of the single blades forming the reed 4. The weft yarn is then conveyed through the channel 3 by pneumatic devices (which need not be described in detail herein) until it reaches the opposite side of the loom. The same yarn feeding device, positioned upstream of the gun 1, then provides to stop the weft yarn 2 after having fed an amount of yarn sufficient to cross the loom. At this point, the reed 4 starts its beating up movement towards the cloth T being woven, leading the launched weft yarn 2 into engagement therewith. During this movement, the yarn 2 must be kept perfectly tense - whereby it is not cut until reed beating up has taken place - and also perfectly straight, and this is obtained by shifting the gun 1 in alignment with the reed 4, of which it follows the oscillating movement. During insertion of a weft, the other wefts resting in the pipes of the gun 1 have to be kept tense in their feeding position, so as to be positively inserted in the shed at the right moment. For this reason, a constant air stream is also present in their respective nozzles, though its pressure is far lower than that used to launch the weft yarn. In conclusion, therefore, the gun 1 blows out a constant air jet in the direction of the cloth being woven, said air jet being more powerful when launching a weft yarn and less powerful after the same has been launched, during closing and reopening of the shed. As seen in the introductory part of the present description, the tucked-in selvedge is formed on the fabric by folding back the weft tails projecting therefrom, soon after the weft has been beaten up, and by newly inserting said weft tails into the shed which has just opened again. According to the method of the present invention, this is obtained by means of a suction and blowing nozzle 5, the free end of which is perpendicular to the longitudinal axis of the loom, i.e. parallel to the direction of the weft yarn launched into the shed. The nozzle 5 comprises, close to its free end, a longitudinal slit 5a opening towards the weft yarn 2 (fig. 4) and meant to facilitate suction of the weft tail into the nozzle 5 when said weft yarn is cut by the cutter 6. The weft yarn sucked into the nozzle 5 is subsequently launched by said nozzle - which has switched onto the blowing function after having been shifted towards the reed - to allow inserting the weft tail into the newly opened shed. To be sure that the weft tail is positively sucked into the nozzle 5, it is first of all necessary for the weft yarn 2 to be cut only when it has practically reached the slit 5a of the nozzle 5; moreover, the weft yarn should not be tensioned or irregularly deviated as cutting takes place, since this would make it unsteady after cutting, whereby the nozzle 5 would have difficulties in correctly performing its functions and, in any case, the length of the weft tails - and thus the width of the selvedge being formed therewith - would not be constant. In addition to this, at loom inlet, there is the problem caused by the presence of the gun 1 and of the air jet blown therefrom, which notably disturbs the correct working of the nozzle 5, both when sucking the weft tail and when subsequently launching the same into the shed. To overcome these problems, the method according to the present invention proposes to screen said air jet by interposing, between the gun 1 and the nozzle 5, a protection screen apt to prevent the air blown from the gun 1 from interfering with the tails of the weft 2. Said protection screen can be set in a fixed position, in correspondence of the position taken up by the weft 2 at the moment of its cutting, or it can be movable into said position - simultaneously with and in a direction opposite to the weft 2 - from a position where its presence is not likely to disturb the operation of weft insertion. According to the present invention, the screen also comprises means to house the weft yarn therein during reed beat-up, so as to preferably avoid any deviations or tensioning thereof, or anyhow reduce these phenomena to a minimum, reproducing them to the same extent for each weft. Said means - which should of course preserve, or only slightly reduce, the effectiveness of the screen - preferably consist of a V-shaped notching, formed in said screen and opening towards the weft yarn, with axis coinciding with the weft trajectory as reed beat-up takes place. A first embodiment of said screen is illustrated in figs. 1 and 2: it consists of a lamina 7 - with a V-shaped notching 7a on the side facing the weft yarn 2 - positioned between the gun 1 and the nozzle 5, so as to deviate far from this latter most of the air blown out from said gun, when weft yarn cutting takes place. During the weft insertion step (fig. 1A), the gun 1 is not screened by the lamina 7, either because the stroke of the reed 4 is of sufficient amplitude to shift said gun beyond the outer edge of the lamina 7, or because this latter is in turn apt to perform a reciprocating movement in the direction opposite to that of the reed 4, and thus moves away from the yarn cutting area during opening of the shed. As the weft yarn is being cut (fig. 1B), the gun 1 has moved in the direction of arrow F, together with the reed 4 and the weft yarn 2 inserted in the shed, while the lamina 7 has possibly moved in the opposite direction G. The strokes of the different members and the depth of the V notching 7a of the lamina 7 are adjusted so that, while being cut, the weft yarn 2 finds itself at the vertex of the V notching 7a, so that the air jet blown from the gun 1 is mostly deviated beyond said lamina 7. The depth of the V notching 7a can be adjusted so that, at the end of reed beat-up, the vertex of said notching is perfectly aligned with the gun 1 (whereby the weft yarn 2 is straight and not tensioned) - as shown in fig. 2B - or it can be adjusted so that the gun 1 is totally screened by the solid part of the lamina 7 (whereby the weft yarn 2 is slightly deviated and tensioned) - as shown in fig. 2A. Reference 1l indicates the position of the gun 1, in respect of the lamina 7, when the weft yarn is launched into the shed, while reference 1t indicates the position taken up by the gun 1, in respect of the lamina 7, when yarn cutting takes place. The drawings clearly show how, in this last position, the air jet blown from the gun 1 is totally screened by the lamina 7 in the embodiment of fig. 2A, and almost totally screened in the embodiment of fig. 2B. The first arrangement (fig. 2A) should be adopted with particularly light and delicate yarns - which cannot even tolerate the slight puff of residual air likely to pass through the slit 7a - even if said yarns have to be slightly tensioned. While the second arrangement (fig. 2B) can advantageously be adopted with stronger weft yarns, for which the already considerable screening action - provided by the lamina 7 in correspondence of the vertex of its slit 7a - is more than enough. The tensioning imparted on the weft yarn 2, in the arrangement of fig. 2A, is in any case not only very slight but also perfectly uniform for each weft yarn, both in its direction and in its value, considering that the position of the weft yarn is univocally determined by the vertex of the notching 7a. Said tensioning thus has no negative effects on the selvedge being formed, but only slightly increases its width (the weft tails being cut when the yarn is in a deviated position are in fact slightly longer than those cut on the yarn in a straight position). Thus, for each single yarn being treated, one can reckon each time an optimal position for the notching 7a - between the two extreme positions shown in figs. 2A and 2B - so as to determine a satisfactory compromise between: protection from the air jet blown from the gun 1, and deviation imparted on the weft yarn 2. In any case, thanks to the particular configuration of the nozzle 5 and to the type of movement which it is apt to perform - described hereinafter - the weft yarn 2 is positively sucked into said nozzle, even when it is in a slightly deviated position determined by the lamina 7. The nozzle 5 is apt to perform a rectilinear reciprocating movement in a direction parallel to the longitudinal axis of the loom, and its position is adjusted so that, when the fixed cutter 6 cuts off the weft, the nozzle 5 - and particularly its slit 5a - is already very close to the weft yarn 2, so that this latter is perfectly stable and is at once sucked into said nozzle during the suction step, as soon as cutting has been performed. As the shed opens again, the nozzle 5 is shifted in the direction G, until it takes up a suitable position facing the open shed, into which it provides to reinsert the weft tail thanks to reversal of the air stream blowing inside the same. Figs. 3, 4 and 5 illustrate a second embodiment of the device to carry out the method of the present invention, always on the inlet side of an air loom. In this case, the screen still consists of a lamina 8 comprising a V-shaped notching 8a, but said lamina is rigidly fixed to the nozzle 5, so that the vertex of the V ends in correspondence of the slit 5a of the nozzle 5. The working of this second embodiment of the device is illustrated in fig. 5, which shows the different reciprocal positions of the reed 4, of the weft yarn 2 and of the lamina 8, when launching the weft (A), when reed beat-up takes place (B), and when yarn cutting is performed (C). For clearness sake, fig. 5 does not illustrate the position taken up by the gun 1, which obviously coincides (of course in these lateral views) with the position of the weft yarn 2. It will be noted that, also in this case, the position of the yarn 2 - when cutting takes place - is quite adjacent to the slit 5a, and that the yarn 2 is never deviated from its rectilinear path. The screens formed by the laminae 7 and 8 can be used both singly and jointly, according to the type of yarn and to the working conditions, in order to obtain the strongest screening effect against the air jet blown from the gun 1. The method and device of the present invention shall now be described with reference to a tucked-in selvedge formed at the outlet of an air loom or of a gripper loom. In the case of a gripper loom, the arrangement illustrated hereinafter can be symmetrically adopted also at loom inlet. At loom outlet - as already explained in the introductory part - there is the problem of the troublesome presence of the reed each time one does not weave at full width of the loom. In such cases, in fact, the devices to cut and fold back the weft tail have to be positioned inside the loom, in correspondence of the right edge of the cloth, and they obviously interfere with the reed while this latter is performing its beating up movement. In prior art, this problem has been solved by cutting the reed, that is, by reducing every time the width of the reed to that required for weaving each specific article. This leads however to the already described inconveniences. According to the method of the present invention, the folding back of the weft tail is obtained - in a way similar to that previously described in relation to loom inlet - by means of a suction and blowing nozzle 9 (figs. 6 and 7), which is caused to advance towards the reed with an independent motion in respect of the cutter 10, up to moving quite close to the weft 2 and to the reed 4, keeping said weft steady thanks to the sucking action through a slit 9a, similar to the slit 5a of the previously described nozzle 5. During said motion, the cutter 10 is at rest, out of reach of the reed 4, as clearly shown in fig. 8. The reed illustrated in this figure is of the type used on air looms, but the method of the present invention can obviously be equally applied in the case of plain reeds used on gripper looms. When the reed 4 has ended its beating up movement and starts its backward stroke, the cutter 10 is shifted in the direction of the weft 2 in order to cut the same, while said weft is kept perfectly steady by the nozzle 9. After cutting, the weft tail is at once sucked into the nozzle 9, which then moves to position 9' to reinsert the weft tail, while the cutter 10 moves back to its rest position. Having separated the movement of the nozzle 9 from that of the cutter 10 allows to obtain a cutting of the weft 2 in position 11, and thus its removal from the split selvedge C, with the weft yarn in perfectly straight conditions, without any uncontrolled non-axial stresses apt to cause the unsteadiness of the weft after it has been cut. If, on the contrary, the nozzle 9 and the cutter 10 were to be reciprocally constrained in the position of maximum approach of the cutter allowed by the presence of the reed and shown in fig. 8, on approaching the unit to allow cutting the weft once the reed had moved away, the weft yarn would be deviated by the nozzle 9 into the position 2'', allowing the cutting to be performed only in 11'', instead of 11, with consequent unsteadiness of the weft upon cutting thereof and great difficulty in leading said weft to be sucked in the nozzle 9. In any case, since the deviation imparted by the nozzle 9 would be quite casual and irregular, the length of the weft tails and thus the width of the selvedge formed therewith would be quite uneven. In the device to form the tucked-in selvedge according to the present invention, the reciprocating movements of the cutting means and of the nozzles to form said selvedge can be performed - in known manner - by means of mechanical devices connected to the general motion of the loom. In this case, also the movements of the nozzle 9 and of the cutter 10 positioned at loom outlet - which are regulated, as previously seen, by different laws - can of course be controlled by suitable kinematic mechanisms. A satisfactory solution of this type, which allows to regulate both the amplitude and the phase of said two movements in a reciprocally independent way, is that illustrated by way of example in fig. 9. In the case of air looms however - which already include a system apt to guarantee a considerable supply of compressed air - it is preferable to adopt solutions making use of totally pneumatic means, in order to obtain the wanted movements of the single members of the device to form the tucked-in selvedge according to the present invention. A particularly satisfactory and compact embodiment of said device is illustrated by way of example in figs. 10 and 11. The different embodiments of the device, illustrated in figs. 9, 10 and 11, shall now be described in detail. A first embodiment is shown in fig. 9. The loom is diagrammatically represented therein by the reed 4 and by the open shed of the warp yarns W. Both the nozzle 9 and the cutter 10 are mounted at the ends of respective movable sliders 12 and 13, caused to move by fully similar kinematic mechanisms briefly described hereinafter. The shafts 14 and 15 are directly controlled by the general motion of the loom and transmit said motion to the cams 16 and 17 by way of flanges 18 and 19 fixed thereto by screws 20 and 21 housed into slots 22 and 23. By shifting the locking position of the screws 20 and 21, one obviously modifies the phase of the movement of the two kinematic mechanisms in respect of the motion of the loom. The cams 16 and 17 cause the oscillation, through a suitable cam-follower, of levers 24 and 25 which are in turn apt, through link rods 26 and 27, to cause the rectilinear reciprocating movement of the sliders 12 and 13. The amplitude of said movement can be independently regulated by shifting the pivoting point between the levers 24, 25 and the link rods 26, 27, along slots 28 and 29 formed in said levers. The cutting action of the cutter 10 - when this latter has reached the cutting position 11 - is instead determined by a fixed profile 30. Reference 9' indicates, also in this figure, the end-of-stroke position of the nozzle 9, namely the position in which the weft tail is inserted again into the open shed. A second embodiment is shown in figs. 10 and 11. Fig. 10 illustrates the device to form the tucked-in selvedge at loom inlet, comprising the motor means apt to determine the wanted movements of its movable parts. Said motor means preferably consist of pneumatic or electromagnetic linear actuators. The first ones are actually preferred owing to their numerous positive characteristics: they can in fact work up to very high frequencies and can thus be used also on high-speed looms; they require only very little maintenance; they use up as power source the compressed air already existing in the loom, the consumption of which is thus optimized; they allow, by regulating the value of the counterpressure in their cylinder (to simplify things, the circuit feeding compressed air of counterpressure has not been illustrated in the drawings), to modify the piston motion law to the desired extent; and, finally, they involve limited costs. The suction and blowing nozzle 5 is moved forward and backward - in the manner described heretofore - by a linear actuator 31, while a second linear actuator 32 controls the cutting movement of the fixed cutter 6. The working stroke of said actuators can be varied within certain limits by changing the dimensions of the respective cylinder; apart from this, the movement determined by their piston rod can be suitably increased or reduced through known type linkages, eventually adjustable. The opening and closing of the pneumatic circuits of actuators 31 and 32 is controlled by respective solenoid valves 33 and 34, electrically connected to the central processing unit controlling the loom. In this way, the working of actuators 31 and 32 can be programmed at will by simply introducing suitable software into said processing unit. Similar solenoid valves 35 and 36 control the sucking and blowing functions of the nozzle 5. The solenoid valve 35 directly controls the feeding of compressed air into the nozzle 5, through a connection block 37, in order to produce the blowing jet. The solenoid valve 36 feeds instead compressed air into a Venturi tube 36, to which are connected - in correspondence of the lowest pressure zone - the nozzle 5 through a pipe 39, as well as said connection block 37, in order to produce the suction jet. By alternatively operating the solenoid valves 35 and 36, which are also controlled by the central processing unit of the loom, one therefore obtains the desired alternate suction and blowing jet into the nozzle 5, which allows to carry out the method of the present invention. The above arrangement, wherein the air suction jet is obtained by using the low pressure of a Venturi tube, provides undoubted advantages in respect of the traditional solution of a mechanical vacuum pump. In fact, the absence of any moving parts totally eliminates the problems tied to oil entrainment (arising in the lubricated pumps), or those determined by seizure of the movable parts (arising instead frequently in the dry vacuum pumps). The arrangement of the device to form the tucked-in selvedge at loom outlet, shown in fig. 11, is specularly identical to that described heretofore. The reciprocating movement of the suction and blowing nozzle 9 is controlled by a linear actuator 41, while the cutting movement of the cutter 10 is controlled by a linear actuator 42, said actuators being operated by respective solenoid valves 43 and 44. Also the suction and blowing jet of the nozzle 9 is determined by the alternate operation of the solenoid valves 45 and 46, the first of which is directly connected to a block 47 to which is pneumatically connected the nozzle 9, while the second one is connected to a Venturi tube 48, the throttled part of which is pneumatically connected to said block 47 by way of a pipe 49. Nevertheless, as previously described, in correspondence of loom outlet the cutting means 10 have to move independently from the nozzle 9, whereby the body of the actuator 42 is not connected directly to the loom structure but to a slide 50 movable on a horizontal plane between a working position and a rest position. The movement of the slide 50 is determined by a further linear actuator 51, controlled by a solenoid valve 52. The slide 50, the actuator 51 and the solenoid valve 52 are drawn in dashes, to indicate that their presence is indispensable only when the loom is working with different cloth widths, so as to avoid having to cut the reed. In the other cases - i.e. when working always with the same cloth width, or when already disposing of reeds for the different widths of the cloth being woven - the elements 50, 51 and 52 can be eliminated, so that the device to form the tucked-in selvedge according to the present invention is perfectly symmetrical on both sides of the loom. As clearly results from the previous description, the method of the present invention has fully reached the intended purpose. It can in fact be carried out by means of very simple and economic devices, it requires no modifications of the loom or of the reed when having to vary the width of the cloth being woven, and it allows to obtain a tucked-in selvedge which is perfectly uniform and has no loose unfolded weft tails. This result can moreover be obtained also on high-speed looms, thanks to the fact that the devices required to carry out the method according to the invention are all of very modest dimensions and can thus be set in reciprocating motion at high speeds, without creating any problems. The method of the present invention has been described with particular reference to some preferred embodiments of the device allowing to carry out the same, but it is understood that its protection is not limited to said embodiments, but covers any possible modifications thereof, within reach of a technician skilled in the art and falling within the scope of the following claims.

Claims: Method to form a tucked-in selvedge in shuttleless looms comprising means to insert the weft yarn (2) into the shed, a reed (4) to beat up the weft yarn (2) thus inserted, and weft yarn cutting means - of the type wherein the weft yarn (2) is cut at a distance from the first and last warp yarn (W) sufficient to form free weft tails, which are inserted again into the shed to be beaten up therein together with the following weft - wherein the method comprises, in succession, the following steps to be carried out after closing of the shed and before a new weft insertion takes place: a) Approaching air suction means (5, 9) to the uncut weft yarn (2), while the reed (4) is in a beating up position; b) Approaching the cutting means (6, 10) to the weft yarn (2), as the reed (4) is leaving the beating up position, while keeping the suction means (5, 9) adjacent to said weft yarn (2); c) Cutting the weft yarn (2) with said cutting means (6, 10), thus allowing the weft tail to be sucked into said suction means (5, 9); d) Moving the suction means (5, 9) to a zone facing the open shed, where the free weft tail is inserted again; and e) Reversing the air stream inside said suction means (5, 9), so as to launch the weft tail into the shed. Method to form a tucked-in selvedge in air looms comprising one or more yarn launching nozzles (1) to insert the weft yarn (2) into the shed, a reed (4) to beat up the weft yarn (2) thus inserted, and weft yarn cutting means - of the type wherein the weft yarn (2) is cut at a distance from the first and last warp yarn (W) sufficient to form free weft tails, which are inserted again into the shed to be beaten up therein together with the following weft - wherein at the weft insertion side the cutting means are fixed and the method comprises, in succession, the following steps to be carried out after closing of the shed and before a new weft insertion takes place: a) approaching air suction means (5, 9) to the uncut weft yarn (2), while the reed (4) is in a beating up position; b) keeping the suction means (5, 9) adjacent to the weft yarn (2) as the reed (4) is leaving the beating up position, while b1) at the weft insertion side screening the air jet blown from said launching nozzles (1); and b2) at the weft delivery side approaching the cutting means (10) to the weft yarn (2) c) cutting the weft yarn (2) with said cutting means (6, 10), thus allowing the weft tail to be sucked into said suction means (5, 9); d) moving the suction means (5, 9) to a zone facing the open shed, where the free weft tail is inserted again; and e) reversing the air stream inside said suction means (5, 9), so as to launch the weft tail into the shed. Method to form a tucked-in selvedge as in claim 1) or 2), wherein said air suction means consist of a suction and blowing nozzle (5, 9), the free end of which is parallel to the weft yarn (2). Method to form a tucked-in selvedge as in claim 3), wherein said suction and blowing nozzle (5, 9) comprises, close to its free end, a longitudinal slit (5a, 9a) opening towards the weft yarn (2). Method to form a tucked-in selvedge as in claim 2), wherein step b') is carried out using a screen, which consists of a lamina (7, 8) interposed between the yarn launching nozzles (1) and the air suction means (5) and comprising a V-shaped notching (7a, 8a) opening towards the weft yarn (2). Method to form a tucked-in selvedge as in claim 5), wherein the position of said lamina (7, 8) is such that, on cutting of the weft yarn (2), this latter finds itself at the vertex of the V-shaped notching (7a, 8a), and the air jet blown from the launching nozzles (1) is totally or almost totally screened by the solid part of said lamina (7, 8). Method to form a tucked-in selvedge as in claim 5) or 6), wherein said lamina (7) is movable between a rest position, far from the launching nozzles (1), and a working position in which it is interposed between said launching nozzles (1) and said air suction means (5). Method to form a tucked-in selvedge as in claim 5) or 6), wherein said lamina (8) is fixedly connected to the suction and blowing nozzle (5) and is movable therewith. Method to form a tucked-in selvedge as in claim 3), wherein the free end of the suction and blowing nozzle (9) is apt to be housed into the launching channel (3) of the reed (4). Device to form a tucked-in selvedge in shuttleless looms comprising means to insert the weft yarn (2) into the shed, a reed (4) to beat up the weft yarn (2) thus inserted, and weft yarn cutting means - of the type in which the weft yarn (2) is cut at a distance from the first and last warp yarn (W) sufficient to form free weft tails, which are inserted again into the shed to be beaten up therein together with the following weft - wherein it comprises air suction means (5, 9) and yarn cutting means (6, 10), independently apt to perform cyclic movements between: a first position, while the reed (4) is in its beating up position, in which said air suction means (5, 9) are adjacent to the weft yarn (2) and to the reed (4), and said yarn cutting means (6, 10) are in a rest position not interfering with the reed (4); a second position, while the reed (4) is leaving its beating up position, in which said cutting means (6, 10) are moved close to the weft yarn (2) so as to cut the same, and said suction means (5, 9) remain, in their previous position so as to suck in the free weft tail; and a third position, while the reed (4) is far from its beating up position, in which said suction means (5, 9) are at the side of the open shed so as to insert said weft tail, which is launched therein by reversing the air stream inside said suction means (5, 9). Device to form a tucked-in selvedge in air looms comprising one or more yarn launching nozzles (1) to insert the weft yarn (2) into the shed, a reed (4) to beat up the weft yarn (2) thus inserted, and weft yarn cutting means - of the type in which the weft yarn (2) is cut at a distance from the first and last warp yarn (W) sufficient to form free weft tails, which are inserted again into the shed to be beaten up therein together with the following weft - wherein, at the weft insertion side of the loom, it comprises: fixed yarn cutting means (6); air suction means (5), apt to perform a cyclic movement between a first position in which they are adjacent to the weft yarn (2) after the same has been launched and before it is cut, so as to suck in the free weft tail, and a second position in which they are at the side of the open shed, so as to insert said weft tail which is launched therein by reversing the air stream inside said suction means (5), when the reed (4) is far from the beating up position; and a screen (7, 8) interposed between said air suction means (5) and the yarn launching nozzles (1), as the weft yarn (2) is being cut, comprising means to house the weft yarn (2) therein; and at the weft delivery side, it comprises: air suction means (9) and yarn cutting means (10), independently apt to perform cyclic movements between: a first position, while the reed (4) is in its beating up position, in which said air suction means (9) are adjacent to the weft yarn (2) and to the reed (4), and said yarn cutting means (10) are in a rest position not interfering with the reed (4); a second position, while the reed (4) is leaving its beating up position, in which said cutting means (10) are moved close to the weft yarn (2) so as to cut the same, and said suction means (9) remain, in their previous position so as to suck in the free weft tail; and a third position, while the reed (4) is far from its beating up position, in which said suction means (9) are at the side of the open shed so as to insert said weft tail, which is launched therein by reversing the air stream inside said suction means (9). Device to form a tucked-in selvedge as in claim 10) or 11), wherein said air suction means consist of a suction and blowing nozzle (5, 9), the free end of which is parallel to the weft yarn (2). Device to form a tucked-in selvedge as in claim 12), wherein said suction and blowing nozzle (5) comprises, close to its free end, a longitudinal slit (5a) opening towards the weft yarn (2). Device to form a tucked-in selvedge as in claim 11), wherein said screen consists of a lamina (7, 8) interposed between the yarn launching nozzles (1) and the air suction means (5), and said means to house the weft yarn (2) consist of a V-shaped notching (7a, 8a) formed in said lamina (7, 8) and opening towards the weft yarn (2). Device to form a tucked-in selvedge as in claim 14), wherein the position of said lamina (7, 8) is such that, on cutting of the weft yarn (2), this latter finds itself at the vertex of the V-shaped notching (7a, 8a), and the air jet blown from the launching nozzles (1) is totally or almost totally screened by the solid part of said lamina (7, 8). Device to form a tucked-in selvedge as in claim 14) or 15), wherein said lamina (7) is movable between a rest position, far from the launching nozzles (1), and a working position in which it is interposed between said launching nozzles (1) and said air suction means (5). Device to form a tucked-in selvedge as in claim 14) or 15), wherein said lamina (8) is fixedly connected to the suction and blowing nozzle (5) and is movable therewith. Device to form a tucked-in selvedge as in claim 12), wherein the free end of the suction and blowing nozzle (9) is apt to be housed inside the launching channel (3) of the reed (4). Device to form a tucked-in selvedge as in any one of claims 10) to 18), wherein the cyclic movements of the air suction means (5, 9) and of the yarn cutting means (6, 10) as well as the cutting movement of said cutting means (6, 10) are controlled, through independent kinematic cam and link rod mechanisms (12-13, 16-17, 24-25, 26-27, 30), by the general motion of the loom. Device to form a tucked-in selvedge as in claim 19), wherein the amplitude and phase of said movements can be independently regulated by mechanical adjustment means (20-21, 28-29). Device to form a tucked-in selvedge as in any one of claims 10) to 18), wherein the cyclic movements of the air suction means (5, 9) and of the yarn cutting means (6, 10) as well as the cutting movement of said cutting means (6, 10) are independently controlled by pneumatic or electromagnetic linear actuators (31-32, 41-42, 51) which can be programmed through a processing unit. Device to form a tucked-in selvedge as in claim 21), wherein said linear actuators (31-32, 41-42, 51) are pneumatically operated and the amplitude, phase and motion law of said movements can be independently regulated, respectively, by mechanical adjustment means, by programming into a processing unit, and by adjusting the counterpressure in the cylinder of said actuators. Device to form a tucked-in selvedge as in any one of claims 10) to 22), wherein the suction jet of said suction and blowing nozzle (5, 9) is obtained by using the low pressure supplied by a Venturi tube (38, 48) fed with a high-pressure air jet.

Inventors: VISCARDI ETTORE, VISCARDI, ETTORE
Applicants: SOMET SOC MEC TESSILE, SOMET SOCIETA' MECCANICA TESSILE S.P.A.
Application year: 1992
Main classification: D03D47
IPC codes: D03D47