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(11) | EP 0 129 812 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Device guiding and braking the weft yarn at the inlet of the shed in shuttleless looms Vorrichtung zum Führen und Bremsen des Schussfadens beim Eintritt des Faches in eine schützenlose Webmaschine Dispositif pour guider et freiner le fil de trame à l'entrée de la foule dans un métier à tisser sans navette |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] This invention concerns a guiding and braking device to improve weft yarn insertion at the inlet of the shed in gripper looms.
[0002] It is known that in shuttleless looms - of the type wherein the weft is fed through the shed by a pair of grippers, the carrying and the drawing gripper, exchanging said weft at the centre of the shed - the operation involving the gripping of the weft by the carrying gripper at the inlet of the shed, and its simultaneous cutting in respect of the already formed fabric, forms the start of the working cycle and is an essential premise for correctly carrying said cycle.
[0003] The proper issue of this initial operation requires to adopt grippers and cutting devices which are apt to guarantee a perfect working with the different types of weft being inserted into a same fabric or into different types of fabric, and even with yarns having an irregular count.
[0004] Usually, a setting of the cutting times and of the gripper retaining means, which may be acceptable for a certain type of yarn, is not suitable for other types of yarns, while the use of yarns having an irregular count prevents proper working when said irregularity is present in the gripping and cutting phase and area.
[0005] Attempts have been made to make the gripping independent from the cutting times, by inserting in looms clamping pincers. In this case, however, the weft insertion on the gripper gives rise to serious problems: in fact the weft yarn, subjected to stretching, may easily break; this may lead to missing of the weft, or else - if the weft portion which has remained on the carrying gripper is not removed by its clamping means - it may cause a running defect in the subsequent working cycle.
[0006] There are already known to be in technique - for example from the DE-A-2534494 - auxiliary devices for selvedge forming apparatuses, which comprise an elastic element pressing on the counterblade of the loom cutting devices, in order to guide and clamp the weft yarn between the fabric being formed and the gripper.
[0007] Nevertheless such devices are not suited, nor have they ever been used or designed to solve the above problem.
[0008] This problem is now solved by the present invention, which concerns a device to improve the insertion of the weft yarn in the carrying gripper of gripper looms equipped with a weft cutting device having a movable blade and a fixed counterblade aligned generally in the weft path direction, said device providing to guide and brake the weft yarn at the inlet of the shed, between the already formed fabric and the carrying gripper, at the moment in which said gripper engages said weft yarn and carries it therewith, characterized in that it comprises an elastic element applied to the weft cutting device of the loom and having a length which presses on a first portion of the counterblade of said cutting device, the weft yarn being pulled between said length of the elastic element and the counterblade by the weft carrying gripper as it enters the shed, and in that the counterblade has a second portion extending beyond the first portion in the direction of insertion of the weft, which second portion is not pressed by the elastic element.
[0009] The invention will now be described in further detail, with reference to the accompanying drawing, which illustrates two preferred embodiments thereof and in which:
Fig. 1 is a perspective view of part of the loom cutting device, to which is applied a first embodiment of the guiding and braking device according to the invention; and
Fig. 2 shows, on a reduced scale, a second embodiment of the guiding and braking device according to the invention, applied to a cutting device as that of figure 1.
[0010] As shown in figure 1 of the drawing, the weft yarn t just tied to the fabric T being formed on the loom, passes through a known-type cutting device C which has to perform the cutting thereof, before being engaged by the carrying gripper P (drawn in dashed lines in its position preceding insertion in the shed). According to the invention. an elastic element 2 - formed, in this embodiment, as a metal strap - is applied to said cutting device C, of which only the counterblade 1 is shown. said metal strap 2 comprising a first substantially vertical length 3, for connection to the cutting device C and adjustment in respect thereof. and a second V-shaped length 4 following downward the first length 3.
[0011] The metal strap 2 is fixed to the cutting device C by being inserted into an appropriate seat and locked therein by a pair of pressure screws 5 with horizontal axis, after having adjusted its position in height by way of the upper screw 6 with vertical axis which retains, between its head and a nut 7, the upper square-bent end 8 of said metal strap 2.
[0012] The apex of the V-shaped length 4 of the metal strap 2 elastically bears onto the counterblade 1 of the cutting device C with a pressure depending on the position in height of the length 3 of said metal strap, which pressure can therefore be adjusted by acting on the screw 6.
[0013] As shown in the drawing, the weft yarn t passes through the cutting device C engaging the counterblade 1 externally to the strap 2. It is hence guided and braked by the V-shaped length 4 of said strap 2, which is elastic and resilient.
[0014] In the embodiment of figure 2, the elastic element is in the form of a wire 2A and comprises a first length 9, substantially parallel to the counterblade 1, and a second length 10 formed as a hook, an intermediate part 11 of which engages with the counterblade 1, pressing against the working surface thereof.
[0016] The adopted arrangement causes the weft yarn to remain permanently stretched and to take up the cutting and gripping positions most suited for the operation; it eliminates all motion relative to the cutting device, onto which is fixed the elastic element (2, 2A), so as to require no kinematic motion and to exclude any tension variations deriving from movements in respect of the cutting member; it lets free the small weft yarn tail attached to the fabric; it is self-cleaning because the weft yarn passage removes all impurity; it introduces no inertias on the yarn (as it has no motion of its own and it operates merely in function of elastic deformations, which vary according to the weft yarn count and adapt themselves thereto); and it allows a very wide range of adjustments.
[0017] The elastic elements 2 and 2A are preferably in the form of a metal strap and of a wire, as shown in the drawing. It is however understood that they could also be made in other forms. Also the mounting and adjustment of the elastic elements 2 or 2A, in respect of the cutting device C, could differ from those illustrated, which have been given by mere way of example.
1. Device in a gripper loom to improve the insertion of the weft yarn (t) in the carrying
gripper (P) of gripper looms equipped with a weft cutting device having a movable
blade and a fixed counterblade aligned generally in the weft path direction, said
device providing to guide and brake the weft yarn (t) at the inlet of the shed, between
the already formed fabric (T) and the carrying gripper (P), at the moment in which
said gripper engages said weft yarn and carries it therewith, characterized in that
said device comprises an elastic element (2, 2A) applied to the weft cutting device
of the loom and having a portion (4, 11) which presses on a first portion of the counterblade
(1) of said cutting device, the weft yarn being pulled between said length (4, 11)
of the elastic element (2, 2A) and the counterblade (1) by the weft carrying gripper
(P) as it enters the shed, and in that the counterblade (1) has a second portion extending
beyond the first portion in the direction of insertion of the weft, which second portion
is not pressed by the elastic element (2, 2A).
2. Device as in claim 1), wherein said elastic element (2, 2A) is applied to the cutting
device through a pair of pressure screws (5) with horizontal axis and is adjustable
in height by means of a screw (6) with vertical axis.
3. Device as in claim 1), wherein said elastic element is formed as a metal strap
(2) having a substantially vertical length (3) for connection and adjustment, and
an operative V-shaped length (4) pressing with an intermediate portion thereof on
the counterblade (1).
4. Device as in claim I), wherein said elastic element is formed as a wire (2A) having
a first length (9) substantially parallel to the counterblade (1) and a second length
ending into a hook (10), an intermediate portion of said second length pressing on
the counterblade (1).
1. Vorrichtung in einer Greiferwebmaschine zum Verbessern des Einführens des Schußfadens
(t) in den Tragegreifer (P) von Greiferwebmaschinen, die mit einer Fadenschneideinrichtung
mit einer beweglichen Schneide und einer festen Gegenschneide versehen sind, die im
wesentlichen mit der Fadenwegrichtung fluchtet, wobei die Vorrichtung den Schußfaden
an dem Einlaß des Faches, zwischen dem bereits hergestellten Gewebe (T) und dem Tragegreifer
(P) in dem Moment führt und bremst, in welchem der Greifer den Schußfaden ergreift
und mitnimmt, dadurch gekennzeichnet, daß die Vorrichtung ein elastisches Element
(2, 2A) umfaßt, das an der Fadenschneideinrichtung der Webmaschine angebracht ist
und einen Abschnitt (4, 11) aufweist, der auf einen ersten Abschnitt der Gegenschneide
(1) der Schneideinrichtungdrückt, wobei der Schußfaden zwischen die genannte Länge
(4, 11) des elastischen Elementes (2, 2A) und sie Schneide (1) von dem Fadentragegreifer
(P) gezogen wird, wenn er in das Fach kommt, und daß die Gegenschneide (1) einen zweiten
Abschnitt aufweist, der sich über den ersten Abschnitt in der Richtung des Einführens
des Fadens erstreckt, wobei der zweite Abschnitt nicht von dem elastischen Element
(2, 2A) gedrückt wird.
2. Vorrichtung nach Anspruch 1, wobei das elastische Element (2, 2A) mittels eines
Paares Druckschrauben (5) mit horizontaler Achse an der Schneideinrichtung angebracht
ist und in der Höhe mittels einer Schraube (6) mit vertikaler Achse einstellbar ist.
3. Vorrichtung nach Anspruch 1, wobei das elastische Element als Metallstreifen (2)
mit einem im wesentlichen vertikalen Abschnitt (3) ausgebildet ist zur Verbindung
und zum Einstellen und mit einem wirkenden V-förmigen Abschnitt (4), der mit seinem
Mittelabschnitt auf die Gegenschneide (1) drückt.
4. Vorrichtung nach Anspruch 1, wobei das elastische Element als Draht (2A) ausgeführt
ist, mit einem ersten Abschnitt (9), der im wesentlichen parallel zu der Gegenschneide
(1) liegt, und einem zweiten Abschnitt, der in einen Haken (10) endet, wobei ein Mittelabschnitt
des zweiten Abschnitts auf die Gegenschneide (1) drückt.
1. Dispositif dans un métier à pinces pour améliorer l'insertion du fil de trame (t)
dans la pince de transport (P) des métiers à pinces dotés d'un dispositif de coupe
de trame comportant une lame mobile et une contre-lame fixe alignée généralement dans
le sens du trajet de la trame, ledit dispositif servant à guider et freiner le fil
de trame (t) à l'entrée de la foule, entre le tissu déjà formé (T) et la pince de
transport (P), au moment où ladite pince engage ledit fil de trame et le transporte
avec elle, caractérisé en ce que ledit dispositif comprend un élément élastique (2,
2A) appliqué sur le dispositif de coupe de trame du métier et comportant une longueur
(4, II) qui appuie sur une première portion de la contre- lame (1) dudit dispositif
de coupe, le fil étant tiré entre ladite longueur (4, II) de l'élément élastique (2,
2A) et la contrelame (1) par la pince de transport de trame (P) alors qu'elle entre
dans la foule, et en ce que la contre-lame (1) comprend une seconde portion s'étendant
au-delà de la première portion dans le sens d'insertion de la trame, laquelle seconde
portion n'est pas appuyée par l'élément élastique (2, 2A).
2. Dispositif selon la revendication 1, dans lequel l'élément élastique (2, 2A) est
appliqué sur le dispositif de coupe par l'intermédiaire d'une paire de vis de pression
(5) à axe horizontal et est réglable en hauteur au moyen d'une vis (6) à axe vertical.
3. Dispositif selon la revendication 1, dans lequel l'élément élastique est formé
comme une patte métallique (2) comportant une longueur substantiellement verticale
(3) le raccordement et le réglage, et une longueur en V opérante (4) appuyant avec
sa portion intermédiaire sur la contre-lame (1).
4. Dispositif selon la revendication 1, dans lequel l'élément élastique est formé
comme un fil métallique (2A) comportant une première longueur (9) substantiellement
parallèle à la contre- lame (1) et une seconde longueur se finissant en un crochet
(10), une portion intermédiaire de ladite seconde longueur appuyant sur la contre-
lame (1).