EP3425094A1

EP3425094A1 - Weft yarn operating device without false selvedge in a gripper weaving loom

Info

Publication number: EP3425094A1
Application number: EP18180039.2A
Authority: EP
Inventors: Massimo Arrigoni; Simone MINETTO; Andrea Panzetti; Dario Pezzoni
Original assignee: Itema SpA
Current assignee: Itema SpA
Priority date: 2017-06-30
Filing date: 2018-06-27
Publication date: 2019-01-09
Anticipated expiration: 2038-06-27
Also published as: CN109208158B; JP7017991B2; JP2019039122A; IT201700073787A1; EP3425094B1; CN109208158A

Abstract

Weft yarn operating device, in a gripper loom, of the type comprising: respective clamping grippers (P) for each one of the waiting weft yarns (T), said clamping grippers (P) being mounted on a same and single support (S) which is arranged at the edge of the fabric being woven; a first motor means (Ms) which moves said support (S) in order to bring the clamping gripper (P) of a weft yarn to be inserted into the shed near a work station (L); a second motor means (Mp) which opens said clamping gripper (P) in opposition to retaining means which maintain the clamping gripper (P) in a closed position; and weft yarn directing means (6, 7) which, during the beating step, convey the weft yarn into said open clamping gripper (P). Support (S) is pivoted about a rotation axis (C) and said gripping grippers (P) are mounted on said support (S) along a circumference arc whose centre lies on said rotation axis (C). Yarn guide means are provided which are integral with said support (S) for passing all said weft yarns clamped by said gripping grippers (P) in a convergence area arranged in close proximity to said rotation axis (C) of support (S).

Description

The present invention refers to a weft yarn operating device in a gripper loom, without formation of a false selvedge on the feeding side of the weaving loom. The weft yarn operating device according to the present invention can also be used in a projectile weaving loom, wherein the projectiles are provided with a weft yarn grip-and-release function on the running projectile, for example as disclosed in European patent application No. 18176734.4 to the same Applicant.

FIELD OF THE INVENTION

As it is known to those skilled in the art, the term false selvedge is meant to indicate a group of additional warp yarns placed at both sides of the warp yarns intended for the formation of the fabric and at some distance therefrom, said warp yarns being interwoven with the weft yarns often by a simple cloth weave, said cloth weave thus differing from the weave with which the fabric is produced.
One object of the false selvedge is to form an area of perfectly stretched weft yarns between the regular warp yarns and those of the false selvedge, on which area a special cutting device can act that separates the false selvedge from the fabric once the fabric is regularly woven, and then at a distance of a few centimeters from the beating line, so that the resulting edge of the fabric, and in particular the weft tail fringe bounding the same, is perfectly regular. Also, another object of the false selvedge is to operate the weft yarn tying function, during the insertion step, thanks to a shed closing mode independent and preferably anticipated in respect to the regular warp yarn closing mode, to fasten the two ends of the weft yarns while they are perfectly stretched and thereby avoid any weft defects in the fabric. Yet another object of the false selvedge is to be the connection point for the waiting weft yarns, as better illustrated below. Finally, a further object of the false selvedge is to be able to use therein warp yarns having physical characteristics differing from those of the warp yarns of the fabric, i.e., that are more suitable for achieving a strong and stable tying of the weft yarns and a stable fastening for the waiting weft yarns.
By "weaving loom feeding side", it is meant the side from which weft insertion occurs, which almost always corresponds to the left side of the weaving loom relative to the position usually taken by the weaver.

BACKGROUND ART

In gripper looms, the false selvedge is typically used, on the feeding side of the weaving loom, to maintain the physical connection between the weft yarns waiting to be weaved and their respective feeding devices, and to allow the carrying gripper to grip them. Upon insertion in the shed, the weft yarns in fact are not cut but remain connected to the fabric on one side - running parallel to the edge of the fabric and being held close to the same by a special guide hook - and to the weft feeding device on the other side, by means of the levers of the weft selector device. Weft cutting then occurs upon selecting a new weft yarn, and precisely after the weft yarn - which is being held stretched between the weft selector device and the edge of the fabric - has been gripped by the carrying gripper and before the same be brought by the carrying gripper inside the shed.
This widespread weaving method naturally entails a considerable waste of material, with respect both to the warp yarns making up the false selvedge, and the portion of weft yarn being woven into the false selvedge, and finally the portion of weft yarn running adjacent to the fabric until the next insertion, which last, depending on the fabric design and therefore on the recurrence frequency of that weft yarn, may be more or less long.
The aim of weaving without using the false selvedge system has already been addressed several times in the prior art; however, when weaving with more than two different wefts, no satisfactory solution, from a textile as well as a mechanical perspective, has been found. In principle, in fact, it is necessary to retain all the waiting weft yarns by means of respective clamping grippers, and then operate on the weft in such a way that, during the weft beating operation on the fabric, the weft yarn that has been picked up from one of said clamping grippers is returned and fastened therein before being cut. Only in this way, in fact, is it possible to eliminate the false selvedge and still obtain a regular cut of weft yarns that allows for the manufacturing of a fabric having a fringe of weft tails with consistent height. In the prior art, pneumatic solutions have also been suggested wherein the inserted weft is tensioned and hold in place, until the next insertion is carried out, by means of pneumatic suction devices. However, these solutions are not even mentioned here, since they lie outside the objectives of the present invention, which is in fact exclusively directed to mechanical solutions.
From a mechanical point of view, the need to arrange the aforementioned clamping grippers of the single weft yarns as close as possible to the edge of the fabric, except for the space required for inserting the weft cutting device, obviously conflicts with the need for a plurality of grippers - in a number equal to the number of different wefts making up the fabric weft pattern - to satisfy this condition in succession, following the weft pattern provided each time for the specific fabric being weaved. There will be briefly illustrated below some of the solutions suggested to date, in which a compromise was sought between these two requirements without however being able to reach a simple, reliable technical solution that would be welcomed by the market, as an alternative to the traditional weaving system with use of the false selvedge.
EP 240075 to PICANOL, published in 1987 , discloses a solution whereby the various weft yarn clamping grippers are parallelly arranged, at increasing distances from the edge of the fabric being woven. Said clamping grippers are movable between: a rest position; a weft presentation position, in coordination with the weft selector; and an alignment position with the fabric line where reinsertion of the beating weft in the respective clamping gripper occurs, by means of a corresponding hook integral with the reed. Said hooks are thus also arranged parallel to each other, at increasing distances from the edge of the fabric being woven and are also of increasing lengths to adapt to the different clamping positions of the individual clamping grippers. This is therefore a mechanically complex solution since each clamping gripper must necessarily have a dedicated control, and one that, in addition, only fully solves the problem for the clamping gripper that is closest to the edge of the fabric, given that, for the next clamping grippers, there still occurs a weft waste of increasing length. Moreover, from a textile point of view, the different weft-to-weft gripping geometry caused by the difference in length of the series of hooks arranged side-by-side, could cause problems with the proper gripping of the weft by the carrying gripper.
US 5492153 to SULZER, published in 1995 , discloses an improved solution to the same problem, whereby the clamping grippers are arranged in a single block and are superimposed on each other in a vertical plane adjacent to the edge of the fabric being woven. A first motor control moves the clamping gripper of the weft of interest toward the fabric line; a second motor control, on the other hand, opens said clamping gripper after the weft of interest has been inserted in the shed, to enable reinsertion thereof into the clamping gripper by means of the beating reed. Reinsertion operation is facilitated by a guide plate provided with a central guide slot, inside which the newly beaten weft yarn is drawn by the movement of the reed. The mechanical structure of this solution is clearly simpler than that of the previous Picanol patent; in addition, this solution allows the weft waste problem to be completely overcome since all the active clamping grippers are brought in the same position, next to the edge of the fabric. From a textile point of view, however, this solution has a significant drawback in that it does not allow a constant tension of the waiting weft yarns to be maintained, since the length of their path varies according to the successive movements of the clamping gripper block. There is therefore a frequent possibility of loosening the waiting weft yarns, which may cause both a failure by the carrying gripper to grip the weft yarns and a mutual entanglement of the weft yarns, which actually lie very close to each other. Moreover, since in this solution the weft clamping grippers are arranged in series and are maintained in the closed position by a single common spring, an independent adjustment of the clamping force cannot be achieved for every single clamping gripper, as is often desirable in the presence of different types of wefts.

SUMMARY OF THE INVENTION

Within this prior art framework, the problem addressed by the present invention is therefore to provide, in a gripper loom, an operating device for the waiting weft yarns allowing for the same results to be achieved in terms of mechanical simplicity, as well as precision and consistency of the weft tail cutting length, as those provided by the solution illustrated in the above-mentioned Sulzer patent, without experiencing the drawback of a change in length of the waiting weft yarn path as the clamping grippers switch position, which may consequently cause the loosening of the weft yarns and result in defects in the fabric.
As part of the solution to this problem, a first object of the present invention is therefore to propose a weft yarn operating device allowing for different clamping grippers to be alternated before a same work station, next to the fabric being woven, and in alignment with the fabric line, without this leading to any substantial variation in the path length of the weft yarn length between said clamping grippers and the relative weft feeding device.
Another object of the present invention is to provide a weft yarn operating device in which any possible interference between the waiting weft yarns is also actively avoided.
This problem is solved, and these objects are achieved, by means of a weft yarn operating device having the features as defined in claim 1. Other preferred features of such a device are defined in the secondary claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the weft yarn operating device according to the present invention will nevertheless be more apparent from the following detailed description of a preferred embodiment thereof, which is provided merely by way of a non-limiting example and is illustrated in the attached drawings, in which:

Fig. 1 is a diagram showing the operating principle of the weft yarn operating device of the invention;
Fig. 2 is a front perspective view of the weft yarn operating device of the invention;
Fig. 3 is a bottom and rear perspective view of the device of Fig. 3;
Fig. 4 is a detailed view of an enlarged detail of Fig. 2 showing the movements of the mobile elements of the device, from which the lower guide plates of the weft yarns have been removed for better clarity;
Fig. 5 is a further enlarged rear view of a comb-like yarn guide for separating and guiding the weft yarns;
Fig. 6 is a plan view of a weft leveling plate used in combination with the weft yarn operating device of the invention;
Fig. 7 is a view of the device of Fig. 2 equipped with a scissor-cutting device;
Fig. 8 is a view of the device of Fig. 2 equipped with a rotating blade-cutting device; and
Fig. 9 is an overall plan view showing the mutual arrangement of the functional elements of the weaving loom cooperating with the weft yarn operating device of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the present invention, to solve the above-mentioned problem in a compact and highly effective manner, it was envisaged to house the various weft clamping grippers required for the independent control of the weft yarns on the outer circumference of a weft switch plate S having the general shape of a circular sector rotating about its rotation axis C, as shown schematically in Fig. 1. In this drawing, by way of example, four weft yarns 1-4 are shown starting from pre-feeders F, each passing through a respective lever of a weft selector A and finally reaching single clamping grippers P that are arranged, as above stated, along an external circumference of the weft switch plate S. The number of wefts that can be managed by the device of the invention is only limited by the size of the switch plate S on which clamping grippers P are mounted in a number equal to the different wefts to be processed. Therefore, although, for ease of representation, the invention is shown in the drawings with respect to the number of four wefts, it should be understood that the number of wefts processed by the device may be any number equal to or greater than two, with the upper limit of processed wefts being determined exclusively by the mechanical bulk and by the need to maintain an adequate separation between the wefts, as will be better illustrated below.
By rotating weft switch plate S about its rotation axis C, each clamping gripper can be positioned near work station L, next to the edge of the fabric, in a retracted position (with respect to the forward direction of reed R) relative to beating line B, where the weft yarns are beaten by reed R against the fabric being woven (Fig. 9). Virtually in the same position, and in any case before reed R reaches the beating line B, the weft cutting is also performed. It should be noted that each weft yarn T is associated with one, and only one, clamping gripper P; that work station L, where the weft gripping and cutting operations take place, is one and the same for all clamping grippers; and that weft switch plate S is rotated to position at side work station L the clamping gripper P associated with the weft yarn being selected for insertion by weft selector A. It is therefore apparent from the foregoing that the control of weft switch plate S is logically connected to the control of weft selector A.
According to a basic feature of the present invention, in order to prevent the tension of the weft yarns from changing during rotation of weft switch plate S, it was envisaged that, at least in theory, all weft yarns should pass near rotation axis C of the switch plate S; in practice, the condition that the weft yarn tension should remain constant is satisfied even when the weft yarns are passed in a convergence zone in close correspondence to rotation axis C. Thanks to this arrangement, in fact, the alternate rotation undergone by weft switch plate S in order to successively bring the clamping grippers of the various weft yarns before work station L, according to the preset weft design, does not involve any substantial elongation or shortening of the weft yarns, thereby achieving an object of the invention.
Importantly, in the illustrated embodiment the waiting weft yarns clamped by the clamping grippers P are well spaced and mutually independent, and therefore do not interfere with the positioning of the selected weft (weft 2 in Fig. 1) or with the passage of carrying gripper G. In the convergence zone around rotation axis C, where the weft yarns run in close proximity, each individual weft path is precisely defined by means of a specific weft guide device that will be described below.
The drawings of Figs. 2 to 8 show a preferred embodiment of the mechatronic device implementing the solution principles described above. This device consists of three main functional groups, namely a weft switching unit, shown in Figs. 2 to 5, a weft cutting assembly that operates before the reed beating, shown in Figs. 7 and 8, and finally a separate element for positioning and holding the weft yarn during the insertion step, shown in Fig. 6.
The weft switching unit comprises a weft switch plate S, having the circular sector shape shown above, hinged on a shaft 1, which rotates relative to axis C and is driven to rotate by a main motor Ms through an articulated quadrilateral 2. As already mentioned, the rotation of the main motor Ms, which is preferably a position-controlled electric motor, is controlled by the central control unit of the weaving loom so as to bring into work station L the clamping gripper P associated with the weft yarn being activated from time to time by the weaving loom selector A. Clamping grippers P are positioned on weft switch plate S along a peripheral circumference arc thereof, whose center lies precisely on rotation axis C.
Along said circumferential arc of weft switch plate S, the clamping grippers are mounted side by side in a vertical position, projecting downwards. Opening controls 3 of said clamping grippers P, acting in contrast to retaining means (for example, spring means or magnetic means) which usually keep clamping grippers P pushed in their closed position, are arranged in the upper part of weft selector S. Opening controls 3 are actuated by a single actuator Mp, preferably a force- or position-controlled linear motor, or even by a simple electromagnet which is provided in a fixed position relative to the weft switch plate S. This fixed position is selected so as the actuator Mp is apt to operate the opening control 3 of a clamping gripper P when, following rotation of weft selector S, this last has been moved into work station L.
In addition to having a more accurate control on the operating times of clamping grippers P, by using a controlled linear motor for actuator Mp it is also possible to use more elaborate ways of operating said clamping grippers P, for example by varying the clamping gripper operation mode according to the features of the specific weft yarn clamped therein. This is a significant improvement over the previous Sulzer solution described above, in which the only actuator could act exclusively in an undifferentiated manner on the individual clamping grippers.
When operating the device, it is therefore possible to identify the following operating steps of the weft switching unit, which steps are represented by corresponding arrows in Fig. 4:

A - the main motor Ms rotates, at the right timing, weft switch plate S for moving the clamping gripper P holding the weft yarn actually being inserted in the correct working position (i.e., at the work station L);
B - when the weft yarn to be inserted is gripped by the carrying gripper G, the actuator Mp activates the opening control 3, thereby opening the clamping gripper P previously positioned into work station L; the carrying gripper G can then draw out the weft from the clamping gripper P without tearing it. Clamping gripper P remains in this open position, i.e. with actuator Mp being activated, for the entire period during which the weft yarn T is being inserted into the shed, until the moment in which the weft yarn T, moved forward by the reed, has been returned inside the clamping gripper P thanks to the geometric relative arrangement of the clamping gripper P in work station L and of the reed. Alternatively, the action of actuator Mp may be modulated to achieve a reduced clamping force of clamping gripper P compared to the one provided by the retaining spring means, thus allowing the weft yarn T to be released as a result of the draught provided by carrying gripper G, only when the weft yarn T reaches a preset tension, while the complete opening of the clamping gripper P is performed while said weft yarn T is being inserted into the shed, timely before the weft is returned into the clamping gripper P by the action of reed R;
C - the movable part of actuator Mp is drawn back and the spring means of the clamping gripper P bring the movable part of said clamping gripper back into its closed position, thus clamping the weft yarn T therein.

The working cycle of the switching unit is then restarted, and the weft switch plate S is either rotated to position the next desired weft yarn, and relative clamping gripper P, into work station L, or remains in its current position if a new insertion of the last inserted weft is expected.
As already stated above, according to a fundamental feature of the invention it is necessary that all weft yarns should pass in a convergence zone as close as possible to rotation axis C of the switch plate S, so that the lengths of the weft yarn paths do not change when switch plate S is rotated in the manner indicated above, thereby maintaining the waiting weft yarns at a constant tension. As far as regards the actual embodiment of this device, it is obviously not possible to pass all the waiting weft yarns into a single passage point, as it would be geometrically desirable, without incurring problems of relative rubbing and unwanted entanglements between the weft yarns in the weft selection and insertion steps.
According to the present invention, this problem is solved in a particularly effective manner by using a comb-like yarn guide 4 for separating the wefts, which is integral with shaft 1 of weft switch plate S and projects downwards from it, as clearly shown in Fig. 4. The comb-like yarn guide 4 consists of a plurality of parallel bars 5 having a cylindric cross-section, sufficient in number to define as many gaps as the processed weft yarns, with the purpose of maintaining the weft yarns well separated from one another and therefore avoiding any entanglement or relative rubbing therebetween, while leaving a full freedom of linear movement to the same weft yarns. Bars 5 are arranged in a circular cylindrical configuration having an axis that coincides with rotation axis C of the weft switch plate S and a radius small enough to render negligible any variation in the path length of the waiting weft yarns during rotation of weft switch plate S, and therefore of comb-like yarn guide 4, so as to control any possible corresponding loosening of the weft yarns within an acceptable range.
As shown in the enlarged detailed view of Fig. 5, the comb-like yarn guide 4 then operates in cooperation with a pair of plates 6 and 7 (removed, for greater clarity, in Fig. 4). Plates 6 and 7 are separated from each other by a weft yarn transit channel, and perform different functions, and specifically:

allow only the selected weft yarn to enter the transit channel, for its successive insertion into the shed;
prevent non-selected weft yarns from entering the transit channel during the rotation of switch plate S and the movement of the levers of weft selector A;
direct the weft yarn to enter into comb-like yarn guide 4 by means of a ramp 7s which is formed in the region of plate 7 adjacent to the transit channel, during the reed beating step.

bars

circular groove

plate

bars

like yarn guide

adjacent bars

plates

As a matter of fact, in this position the interested weft yarn does not find any restraint when abandoning comb-like yarn guide 4 under the action of weft selector A, and so the insertion cycle thereof can be started regularly. When insertion of the weft yarn is positively concluded, due to the geometric shape and arrangement of the plates 6 and 7 and to the fact that, in the meantime, the lever of weft selector A has returned to its rest position, the beating movement of the reed let slide the weft yarn under plate 6 and toward plate 7, until the inclined terminal ramp 7s of plate 7 facilitates the re-entry of the last inserted weft yarn between the corresponding bars 5 of the comb-like yarn guide 4, thus closing the weft yarn insertion cycle. A further rotation of the weft switch plate S, or keeping it still in its last position, then respectively allows to switch to another weft yarn, or to maintain the last one, for subsequent weft yarn insertion. In this way, the second object of the invention is also achieved.
Once the operations on the weft yarn described above have been correctly completed, namely:

presentation to the carrying gripper;
insertion in the shed;
housing in the comb-like yarn guide 4; and
clamping in the respective clamping gripper P;

Fig. 7

Fig. 8

A further element of the weft yarn operating device of the invention, useful for the proper operation of the device when negative-type carrying clamping grippers are being employed in the weaving loom, is the so-called weft leveling plate. This element is physically distinct from the weft yarn operating device of the invention but is closely linked thereto from a functional point of view, as will be better understood from the following description.
By "leveling plate", as this definition is understood in the relevant art, it is meant a mechanical element fixed on the weaving loom, at the shed inlet, which is provided with a weft yarn sliding surface and is adapted to ensure that the weft yarns being selected and lowered by weft selector levers A are kept at an appropriate and constant height, suitable for allowing the correct gripping of said wefts by the carrying gripper G, regardless of which lever of the weft selector has been lowered. As a matter of fact, the wefts thus lying on the weft leveling plate slide thereon during the carrying gripper G initial run, until the tension of the weft yarn becomes such as to allow negative clamping thereof by the carrying gripper G.
In the weaving looms of the known type, which use the false-selvedge system, the correct acute-angle arrangement of the weft yarn in respect of the carrying gripper G, during the clamping operation, is determined by the presence of the traditional cutting device. As a matter of fact, the usual mounting position of this device on the loom, i.e. close to the trajectory of the carrying gripper G, provides a weft yarn supporting point during the initial run of said gripper, allowing the weft yarn to be inserted into the gripper according to the preset and correct angular position.
In the device of the invention, on the other hand, a similar arrangement is no longer possible, since the free end of the weft yarn is already separated from the fabric and clamped in the clamping gripper P at the work station L, and therefore in a position further away from the path of the carrying gripper G. Therefore, to provide the geometric condition of a weft yarn support and rotation point near the trajectory of carrying gripper G during the gripping step, according to the invention, the forward end of the weft leveling plate 9 is provided with a hook 10 having a narrow, elongated V-shape. As carrying gripper G advances, the weft yarn slides on the weft leveling plate until it is hooked into the hook 10, thus achieving a suitable support and rotation point for the correct angular positioning of the weft yarn, and hence an effective gripping of the weft yarn by the negative carrying gripper G.
By modifying the position of the weft leveling plate 9 and/or the shape of hook 10, it is possible to change the weft gripping timing and therefore to adjust weft insertion in the carrying gripper and the length of the free end portion of the gripped weft.
If, on the other hand, the weaving loom is equipped with a positive carrying gripper, obviously it is not necessary to have hook 10 on leveling plate 9, since in that case the gripping timing is determined by the same positive carrying gripper.
It should be apparent from the foregoing description that the weft yarn operating device of the invention has fully achieved the preset objects and solved the underlying problem of the invention by providing a device which do not need a false selvedge and, moreover, is particularly compact and completely free from the drawbacks of the prior art devices of this type. By using this device, it is therefore possible to achieve significant cost savings in textile material, to which of course must be added the savings of eliminating all that is necessary for manufacturing the false selvedge, i.e., the mechanical elements, the selvedge warp, the selvedge warp beam, and the costs associated with preparing the latter.
Finally, it should be noted that, as mentioned above, a further reduction in weft waste on the arrival side of the weaving loom may be achieved when a positive gripping mode is used, which allows to reduce the length of the free terminal portion of the weft yarn gripped in the carrying gripper.
It is understood, however, that the invention should not be construed as limited to the arrangements illustrated above, which only represent exemplary embodiments thereof, but that different variations are possible, all being within the reach of a person skilled in the art, without thereby departing from the scope of the invention, which is only defined by the following claims.

Claims

Weft yarn operating device, in a gripper loom, of the type comprising: respective clamping grippers (P) for each one of the waiting weft yarns (T), said clamping grippers (P) being mounted on a same and single support (S) which is arranged at the edge of the fabric being woven; a first motor means (Ms) which moves said support (S) in order to bring the clamping gripper (P) of a weft yarn to be inserted into the shed in correspondence of a work station (L); a second motor means (Mp) which opens said clamping gripper (P) in opposition to retaining means which maintain the clamping gripper (P) in a closed position; and weft yarn directing means (6, 7) which, during the beating step, convey the weft yarn into said open clamping gripper (P) characterised in that said support (S) is pivoted about a rotation axis (C) and said clamping grippers (P) are mounted on said support (S) along a circumference arc whose centre lies on said rotation axis (C) and in that yarn-guide means, integral with said support (S), are furthermore provided to cause all said weft yarns (T) clamped by said clamping grippers (P) to pass through a convergence area arranged in close proximity to said rotation axis (C) of the support (S).
Weft yarn operating device as in claim 1, wherein the rotation of the shaft (1) of said support (S) around said rotation axis (C) is driven by said first motor means (Ms) through an articulated quadrilateral leverage (2).
Weft yarn operating device as in claim 1, wherein opening controls (3) for each one of said clamping grippers (P) are provided, said opening controls (3) being operated by said second motor means (Mp), and said second motor means (Mp) being fixedly positioned with respect to the support (S) carrying the clamping grippers (P), so as to be moved on the opening controls (3) of any clamping gripper (P) following the rotation of the support (S) .
Weft yarn operating device as in claim 3, wherein said second motor means (Mp) is a linear actuator or an electromagnet.
Weft yarn operating device as in claim 4, wherein said retaining means are spring means or magnetic means.
Weft yarn operating device as in claim 5, wherein said work station (L) is positioned rearwards (with reference to the forward direction of the reed) of the beating line (B).
Weft yarn operating device as in claim 1, wherein said yarn-guide means consist of a comb-like yarn guide (4) which is integral with the shaft (1) of support (S) and rotates therewith.
Weft yarn operating device as in claim 7, wherein said comb-like yarn guide (4) comprises a plurality of parallel bars (5), which define as many gaps as the number of the processed weft yarns, said bars (5) being arranged in a circular cylindrical configuration whose axis is coincident with the rotation axis (C) of the support (S).
Weft yarn operating device as in claim 8, wherein said weft yarn directing means comprise a pair of adjacent plates (6, 7), positioned at the free end of said comb-like yarn guide (4) and mutually separated by a transit channel of the weft yarns (T) .
Weft yarn operating device as in claim 9, wherein said plates (6, 7) are substantially perpendicular to said bars (5) and the free ends of said bars (5) slide within a circular groove (8) formed partly in the one and partly in the other of said plates (6, 7), said groove (8) having the same radius and the same axis of the cylindrical con-figuration of said bars (5) .
Weft yarn operating device as in claim 9, wherein one of said plates (7) is provided with a ramp (7s) apt to guide the entry of the weft yarns (T), during the beating step, into said comb-like yarn guide (4).
Weft yarn operating device as in any one of the preceding claims, in a weaving loom provided with a negative carrying gripper, furthermore comprising a weft leveling plate (9) which, at its forward end, is provided with a hook (10) having a narrow and elongated V-shape intended to form a support and rotation point for the weft yarn (T) while the carrying gripper (G) advances in its initial run.
Weft yarn operating device as in any one of the preceding claims, furthermore comprising a weft cutting device, arranged between the edge of the fabric being woven and the clamping gripper (P) placed at the work station (L), said cutting device being provided with a scissor (K) or rotating-blade (H) mechanical cutting unit.