EP0136243A1 - Weft measuring device for looms - Google Patents

Abstract

Weft measurer for a particularly shuttleless weaving loom of the type comprising a pair of propellant rollers (20, 23), the envelopes of which touch each other so as to form a nip between which the weft thread is introduced intermittently by means of guide elements (24) actuated according to the weft insertion program, characterized in that at least one of the rollers (20) has a structure such that the end of the line pinch to which the wire is carried at the start of the measurement moves cyclically.

Description

The present invention relates to an improvement. provided to weft measuring devices used in non-shuttle weaving looms, i.e. to delivery-measuring devices supplying the weft yarn with a storage chamber (reserve) used to temporarily accumulate a determined length of weft yarns before its insertion into the crowd.

Non-shuttle weaving looms, particularly looms whose weft is thrown through the crowd by a medium under pressure (air jet, water jet), or by the energy communicated to the mass of the thread itself. even are all equipped with a measurer which makes it possible to determine as exactly as possible the length of the picks in order in particular to be able to reduce the losses which result from the wire leaving the crowd on the sides of the fabric formed. Furthermore, such meters must be able to be used for wires which may have different characteristics, which is the case in particular in multi-line trades in which the measurement of the wire is intermittent.

The meters offered to date can be divided into two main classes, namely, those with drum where the length is determined by a number of turns and those with unwinding where the wire is pinched between two rotating rollers. The first, more mechanically complicated, are fairly precise while the second, if they are of a simpler design, lack precision and are difficult to use on multi-line looms for which threads of different nature must be thrown at a rhythm already determined.

This drawback is perfectly explained by the mode of operation and the structure of such meters. Indeed, in these meters, the length of the wire is determined either by an intermittent spacing of the rollers, or by temporary introduction of the wire between these rollers which are then kept in permanent contact. The precision of the measurement by successive spacings of the rollers is independent of the size of the wire which is often variable, of the coefficient of friction of the wire on the rollers which can vary according to the orientation of the fibers. In addition, especially when working at high speeds, there may be a rebound of the movable roller on the drive roller and therefore an error in the measurement of the length of the wires.

In the measuring devices for which the rollers are kept in permanent contact, the lack of precision is due to several harmful factors occurring mainly at the time of the entry of the wire between the rollers. To facilitate this entry of the wire, it has been proposed to provide a slight peripheral chamfer as shown in US-A-3 833 028. However, in this case, the effect is similar to that of bringing the two surfaces together in the case of a roller system with temporary spacings and therefore has the same drawbacks as those mentioned above, in particular when it comes to working alternately on the same loom of wires of different nature and which can therefore have a variable size. Another problem which arises with such a type of measurer is that of the disturbing effect produced by the air current resulting from the rotation of the rollers on the introduction of the wire between said rollers. In fact, the surface of the rollers' envelopes causes a thin layer of air, or boundary layer, at its peripheral speed, air which cannot therefore pass the nip and escapes laterally tending to repel the wire at the moment. of its introduction between the rollers.

Finally, the adjustment of this type of meter according to the width of the fabric to be produced (operation of delaizage) is difficult to achieve.

It has also been proposed (FR-A-1 492 449), in a field other than weaving, namely that of spinning, a yarn supply device comprising two rotary rollers, one motor, the other presser. In this device, the pressure roller has a notch on one of its edges in order to allow the wire to be transported from the repair plane (knotting) to the plane in which said wire is taken between the rollers.

However, such a solution cannot be transposed to the gauges used on the weaving looms because it does not allow to have a synchronism with the weaving cycle.

The invention aims to overcome these drawbacks and relates to a meter of the type according to which the rollers are in permanent contact (that is to say do not rise to stop its flow), and which not only allows an exact measurement of the pick to insert but can also be used on multi-color looms, which was not possible with this type of device and which, moreover, has a very easy adjustment, especially when you want to change the length of the measured wire, for example in the case of deliasing.

In the present description, the expression "permanent contact" should not be taken in its strict sense but also designates the case where a slight clearance exists between the rollers, clearance which, however, must be less than the diameter of the wire to be measured. Of course, in the case where a game exists between the two rollers, these elements are driven positively.

In general, the invention relates to a weft meter for weaving loom (more particularly for shuttleless weaving looms whose weft is launched through the crowd by a medium under pressure or by the energy communicated to the mass of wire by a launching mechanism), type meter comprising a pair of propeller rollers driven continuously in rotation and whose envelopes form a pinch line between which the weft thread is introduced intermittently by means of guide elements actuated by function of the weft insertion program, characterized in that at least one of the rollers has a structure such that the end of the pinch line towards which the wire is carried at the start of the measurement moves cyclically and in synchronization with the business cycle.

The length of the nip varies cyclically and is obtained in various ways, for example by providing at least one notch or cell on at least one of the sides of one of the rollers.

According to one embodiment of the invention, thanks to such a device, it is possible to introduce the weft thread between the measuring rollers very precisely and to use one and the same measurer for son of different nature. Indeed, during the time after which the nip is shortened, the wire, under the action of the guide means, will be advanced without obstacle on the other roller then, when this nip is lengthened, it will be taken under the latter.

In the following description, for the sake of simplification, the roller, the structure of which is such that it makes it possible to vary the length of the pinch line in synchronism with the cycle of the trade and thus allowing the measurement, will be designated by l expression "pebble notched".

When the variation of the length of the nip is done quickly, that is to say, for example when the roller has a large number of successive notches (see at the limit an infinity of notches) on one of its sides, it is possible to operate it without having to worry about synchronizing it with the business cycle, synchronism then being achieved automatically.

On the other hand, when the variation of the nip is done for a fairly long period, for example on a half-rotation of the roller in the case where the notches are in the form of two symmetrical cut sides, it is necessary to synchronize said roller with the loom cycle, this being obtained mechanically by making the notches on the drive roller, so that the variation in the length of the pinch line occurs in a well determined position in synchronism with the loom cycle.

The end of the nip can be moved either at the same speed in one direction and in the other, or more quickly in one direction than in the other. This speed variation can be obtained by giving the notch (or cell) an asymmetrical shape. According to a preferred embodiment, the movement is done slowly inward (decrease in the nip) and quickly outward (increase in the nip). Thus, the setting in motion of the wire can be done with very high precision.

Furthermore, the guide element making it possible to introduce the wire between the rollers can also have a faster movement in one direction than in the other. This movement will be combined with the movement of the end of the pinch line.

Finally, it is possible to vary, within a certain limit, the length of the measured wire. This is obtained by angularly shifting the notched roller with respect to the movement of the guide element.

• - les figures 1 et la sont des vues schématiques montrant les forces actives qui s'exercent pendant la pénétration du fil entre les galets d'un mesureur réalisé conformément à l'art antérieur ;
• - la figure 2 est une vue en perspective, d'un dispositif mesureur réalisé conformément à l'invention et dans lequel l'un des galets présente une multiplicité d'alvéoles de forme symétrique permettant de faire varier périodiquement la longueur de la ligne de pincement entre les galets ;
• - la figure 3 illustre une variante selon l'invention comportant deux alvéoles symétriques, sous forme de pans coupés ;
• - la figure 4 est un diagramme temps/chemin du mouvement de l'extrémité des lignes de pincement et du mouvement de l'élément de guidage du fil ;
• - les figures 5 et 6 illustrent la mise en oeuvre d'un dispositif mesureur conforme à l'invention, plus particulièrement du type illustré par la figure 3, sur un métier à tisser ainsi que des moyens permettant de modifier la longueur du fil en décalant angulairement le galet à alvéole, la figure 5 étant une vue en plan et la figure 6 une vue de côté.

The invention and the advantages which it brings will be however, better understood thanks to the exemplary embodiments given below by way of non-limiting example and which are illustrated by the appended diagrams in which:

• - Figures 1 and la are schematic views showing the active forces which are exerted during the penetration of the wire between the rollers of a measurer produced in accordance with the prior art;
• - Figure 2 is a perspective view of a measuring device produced in accordance with the invention and in which one of the rollers has a multiplicity of cells of symmetrical shape allowing the length of the nip to be varied periodically between the rollers;
• - Figure 3 illustrates a variant according to the invention comprising two symmetrical cells, in the form of cut sides;
• - Figure 4 is a time / path diagram of the movement of the end of the pinch lines and of the movement of the wire guide element;
• - Figures 5 and 6 illustrate the implementation of a measuring device according to the invention, more particularly of the type illustrated in Figure 3, on a loom as well as means for changing the length of the thread by shifting angularly the honeycomb roller, FIG. 5 being a plan view and FIG. 6 a side view.

If reference is made to the appended figures and more particularly to FIGS. 1 and 1a, when it is desired to measure a determined length of wire (1), subjected to a tension (2) by any suitable means, for example by means of '' a current of air, by means of a measuring device consisting of two rollers (3,4), said wire being introduced by means of a movable guide element (6), it will be stopped at the end of the pinch line (9) and will form a widening angle _{0 \} until the resulting (7) forces (2) balance the penetration resistance (Figure la). This resistance varies with the size of the wire. One of the components of this resistance is formed by a stream of air exiting on both sides of the rollers (3,4) in front of the pinch line (9). The movement of the rollers (3,4) causes a layer of air which, arriving towards the obstacle constituted by the pinch line (9), follows the direction represented by the arrows (5). The wire (1) blocking the lateral gap between the rollers (3,4) is consequently subjected to a thrust which more or less delays the pinching of the wire.

Tests have shown that the angleoc varies. Consequently, at the speeds currently in use, which are commonly of the order of 40 m / sec, a small variation of α corresponds to large differences in measured length, of the order of 5 to 10 cm. In addition, with such a device, it is difficult to introduce wires of different nature, which is the case in multi-color trades.

These drawbacks are overcome thanks to the device according to the invention.

Thus, in the example illustrated in FIG. 2, the measurer also consists of two rotary rollers (10-12) but one of the rollers, (10) in the present case, has on one of its faces a plurality of cells (11), distributed along its periphery. These cells (11) therefore make it possible to modify the length of the pinch line between the roller (10) and the roller (12). Indeed, this pinch line will have a shorter length at the passage of the cell (11), which moves it away from the wire which is then retained by the prominence (14) and allows the air current to disperse without influence the thread. The wire (1) may, under the action of the guide element (13), penetrate between the rollers (11,12), until the arrival of the protrusion (15) which will pinch it, said wire being, during this transverse movement, in contact with the periphery of the roller (12).

Figures 3,4, 5 and 6 illustrate the structure and operation of a measuring device according to the invention which allows, in addition to an exact measurement, to be able to adjust the measured length of the wire.

In this embodiment which, as previously consists of two rotary rollers (20,23), one of the faces of the roller (20) comprises two cut sides (21), essentially formed by two helical surfaces connected by planes ( 22) substantially axial. This roller (20) forms, with the roller (23), a pinch line of variable length represented on the time / path diagram of FIG. 4 by the zig-zag line "A", each zig-zag corresponding to a half -turn of the roller (20). A guide element (24) makes it possible to move the wire (25) tangentially or with a slight interlock on the roller (23) and follows the helical surface (21) without penetrating between these rollers. This movement is represented in FIG. 4 by the curve "B". The measurement begins when the axial plane (22) comes into contact with the roller (23) (at "C") and ends when the guide element (24) takes the wire (25) out of the pinch line (at "D").

By shifting the movement "A" relative to "D" or vice versa (dotted line "B _" ), the measurement time t is therefore changed, the length measured. To have a repetitive measurement, it is necessary to synchronize the speed of rotation of the cell roller (20) of the measurer with that of the trade. To do this, the number of turns of the cell roller per loom must be 1 / N, N being the number of cells arranged in an angularly equal distribution. In the example in Figure 2, the roller (10) should rotate 1/8, ... 5/8 ... 15/8 ... lathes.

Such a device can be adapted, as shown in Figures 5 and 6, in order to voluntarily offset the movements between the roller (20) and the guide element (24) to vary the length of the measured wire, which allows obtain a normal offset without having to change the speed of the meter.

Such an offset can be obtained as illustrated in Figures 5-6.

Referring to these figures, the wire (30) is drawn from a spool (31) and passes through a guide element (32). In its standby position, the wire makes a slight interlock on the roller (33) outside the nip between the rollers (33) and (34). A reserve (49), conventional, formed of a flat tube in which is created a current of air stores the wire delivered by the measurer waiting to be blown into the crowd (not shown) by any suitable means of launching by example a pneumatic nozzle (50). A brake (51) having a variable braking pressure controlled with the rhythm of the loom is interposed between the coil (31) and the guide element (32).

The honeycomb roller (34) is integral with a toothed pinion (35) driven by the planet gears (36,37) rotating around an axis (39) fixed in a support (41) and able to move around the pinions (35) and (38).

The pinion (38), coaxial with the pinion (35) is connected to the shaft (40) of the loom by gear (43) and a pair of bevel gears (44,45). On the shaft (40) of the loom is keyed a cam (46) acting on the roller (47) and the lever (48) of the guide element (32). By moving the handle (52), the movement of the honeycomb roller (34) is offset relative to the movement of the guide element (32) and, therefore, it is possible to vary the length of the measured wire. Such an adjustment can, moreover, be carried out during the even the trade. A blocking of this lever (52) makes it possible to maintain its position, however the correct adjustment of the length of wire obtained.

By way of example, it is thus possible to obtain, with a roller of 180 mm in diameter, rotating six times faster than the loom, a variation in the length of pick measured between 220 cm and 180 cm, which allows, without having to change the speed of the measurer, to have the possibility of obtaining a normal offset.

Of course, the invention is not limited to the exemplary embodiments given above but it covers all the variants produced in the same spirit. Thus, it could be envisaged to apply the invention to meters whose rollers have shapes other than cylindrical, for example to meters comprising conical rollers. In addition, the shape of the notches made on one of the rollers in order to vary the nip length may be adapted according to the working conditions. Thus, for example, if the entry and exit movement of the guide eyelet (6, 24) is rapid, the configuration of the sawtooth notches of FIG. 4 may be replaced by notches of rectangular configuration.

In addition, it is possible to use a single roller for two guide elements by providing notches on each of the sides of the roller, said notches being preferably made on the drive roller to avoid the risks of slipping and inaccuracy of the measured.

In addition, to avoid too sudden starting of the wires, one can provide, on the edge delimiting the growing pinch line, that which takes the wire, a slight bit (27) on the periphery (26) of the roller.

Finally, the surface of at least one of the rollers forming the pinch line will preferably be covered with an adherent or elastic coating.

Claims (14)

1 / Weigher for weaving loom (more particularly for weaving loom without shuttle whose weft is launched through the crowd by a medium under pressure or by the energy communicated to the mass of the thread by a launching mechanism) , type measurer comprising a pair of propellant rollers (3,4) whose envelopes touch one against the other so as to form a nip between which the weft thread is introduced intermittently by means of elements guide (6) actuated according to the weft insertion program, characterized in that at least one of the rollers (4) has a structure such that the end of the nip towards which the wire is carried at the start of the measurement moves cyclically in synchronism with the business cycle. 2 / weft meter according to claim 1, characterized in that the length of the nip varies cyclically over a large part of the circumference of the driven roller and is obtained by providing at least one notch (or cell) (11) on the side of the roller (4) through which the wire is introduced. 3 / weft measurer according to claim 1, characterized in that it comprises at least one notch or cell (11) on each of these two sides thus allowing its use for two guide elements (6). 4 / weft measurer according to one of claims 1 to 3, characterized in that the displacement of the end of the nip is faster in one direction than in the other. 5 / weft measurer according to claim 4, characterized in that the end of the pinch line moves quickly outwards and slowly inwards. 6 / weft measurer according to claim 4, ca _~ acted by the fact that the wire guide element moves more quickly in one direction than in the other. 7 / weft meter according to claim 5, characterized in that the speed of movement of the pinch line and the speed of the guide element are combined. 8 / weft measurer according to one of claims 1 to 7, characterized in that the notched roller has a single cell determining the length of the nip lines and makes a whole number of turns during a business cycle. 9 / weft measurer according to one of claims 1 to 7, characterized in that the roller has N cells arranged in an angularly equal distribution, the roller making a multiple of 1 / N turn during a cycle of the trade, N being an integer. 10 / weft measurer according to one of claims 1 to 9, characterized in that the roller having cells determining the variation in length of the nip lines can be angularly offset with respect to the cycle of the guide element. ll / Weft measurer according to one of claims 1 to 10, characterized in that the notch giving the variation of the length of the nip is produced by a flap (21) formed essentially of a helical surface and by a substantially axial plane (22). 12 / Measurer according to claim 11, characterized in that the edge between the axial plane (22) and the periphery (26) of the roller has a slightly rounded portion followed by a slight bevel (27). 13 / weft measurer according to claim 1, characterized in that the roller is driven by the loom through a system planetary gears (39,40,41,42) making it possible to offset the movement of the roller relative to that of the loom during its movement. 14 / Weft measurer according to one of claims 1 to 13, characterized in that, at least one of the rollers is covered with an elastic coating.

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