EP0238420B1 - Apparatus for detecting individual threads in a web of parallel threads - Google Patents

Abstract

This invention relates to a device for detecting the presence of an individual yarn in an advancing lap of parallel yarns, constituted by: detector disposed on one side and in the vicinity of this advancing lap, adapted to detect the presence of a yarn moved away from the lap by a blower means disposed on the other side of said lap; an arrangement, controlled by the detector, for stopping the advancing lap or for triggering off an alarm system, wherein: it is composed, in known manner, of a plurality of parallel comb teeth, between which the advancing yarns pass; and the blower is placed at the base of said teeth and directs the flow of air towards the tip of these teeth. The invention is more particularly applicable to warp knitting machines.

Description

The invention relates to a new type of detector for the presence of an individual thread in a sheet of parallel threads and more particularly in a warp knitting machine; it also relates to trades comprising such detectors.

• - d'une part, détecter la présence ou l'absence de chaque fil élémentaire ;
• - d'autre part, corrélativement, arrêter immédiatement la machine ou donner une alerte.

In a sheet of parallel threads in movement, it is essential that we can accurately:

• - on the one hand, detect the presence or absence of each elementary wire;
• - on the other hand, correlatively, immediately stop the machine or give an alert.

• - tout d'abord, de ne pas érailler le fil qui défile, ni de modifier sa tension ;
• - ensuite, d'avoir une inertie la plus faible possible, de manière à pouvoir actionner rapidement les organes d'arrêt de la machine, du moins avant que le défaut détecté n'arrive aux organes de travail (aiguilles, lisses, etc.) ;
• - enfin, d'être peu encombrant, sensible à des faibles tensions, c'est-à-dire à des tensions de l'ordre du gramme, qui néanmoins, peuvent fluctuer autour de cette valeur.

Thus, a wire detector, sometimes also incorrectly called "wire breaker", is asked:

• - first of all, not to scratch the thread that runs, or to modify its tension;
• - then, to have the lowest possible inertia, so that the stop devices of the machine can be actuated quickly, at least before the detected fault reaches the working members (needles, heddles, etc.) ;
• - Finally, to be compact, sensitive to low voltages, that is to say voltages of the order of a gram, which nevertheless can fluctuate around this value.

To date, two methods have essentially been proposed for detecting the presence of a wire in a traveling web.

It was first proposed to carry out the detection on each individual wire. This solution is sought on a technical level, because it should give precise results. However, despite all the efforts and the large number of solutions proposed to date, none has yet really imposed itself, which clearly shows the difficulty of the problem to be solved.

It has also been proposed to carry out this detection no longer on the individual yarns themselves, but on the sheet itself. Thus, it has been suggested to have a light beam such as an optical ray in the vicinity of the moving web, which, when crossed by the slack or broken thread, triggers the stop system of the knitting machine. However, this solution requires the use of an additional blower, disposed on the back of the traveling web, with respect to the light beam, so as to keep the broken or relaxed wires well away from the traveling web and thus cause them to pass through. the light beam. This solution, which is moreover exploited, has proved in practice to be of questionable reliability, to have a non-negligible operating cost and above all requires applying an appreciable blowing force in order to properly move the relaxed thread. Also, frequently, multiple incidents cannot be detected by this type of detector (see German patent DE-A-2 034 815).

As already said, to date, despite a multitude of solutions proposed, none of these solutions has been found satisfactory for the detection of the presence of a wire in a sheet of parallel son running, especially with a low voltage.

The invention overcomes these drawbacks. It targets a detector device of the last type in question, which is effective, compact, sensitive, does not scratch the wire, does not modify its tension, has low inertia, or is operational in most positions, which the we did not know how to obtain industrially until then, and finally be economical to build, assemble, operate and finally does not complicate the journey of the wire.

• - des moyens pour faire défiler la nappe de fils parallèles ;
• - un moyen disposé d'un côté et au voisinage de cette nappe en défilement, apte à détecter la présence d'un fil écarté de la nappe par un moyen de soufflage disposé de l'autre côté de ladite nappe ; - un moyen, actionné par le moyen de détection, pour arrêter les moyens de défilement ou déclencher un système d'alarme,

se caractérise :

• - en ce qu'il se compose, de manière connue, d'une pluralité de dents de peigne parallèles, entre lesquelles passent les fils en défilement ;
• - et en ce que le moyen de soufflage est placé à la base desdites dents et dirige le flux d'air vers la pointe de ces dents.

This device for detecting the presence of an individual wire in a sheet of parallel wires, of the type constituted by:

• - Means for scrolling the sheet of parallel son;
• - A means arranged on one side and in the vicinity of this traveling web, capable of detecting the presence of a wire spaced from the web by a blowing means disposed on the other side of said web; a means, actuated by the detection means, for stopping the scrolling means or triggering an alarm system,

characterized :

• - in that it consists, in a known manner, of a plurality of parallel comb teeth, between which the threads pass in passing;
• - And in that the blowing means is placed at the base of said teeth and directs the air flow towards the tip of these teeth.

In other words, the invention consists in using comb teeth which, in known manner, serve to regularly space each wire, but also, and this is new, serve to channel the flow of air blown to the base of the teeth and thus to move the relaxed or broken wire towards the detection means and this, with sufficient force, although generated by a low air flow. Thus, not only is the compressed air intended for moving the wire substantially saved, but also the probability of detection is considerably increased.

• - les dents caractéristiques comportent une fenêtre placée dans la zone située vers la pointe de la dent et le moyen de détection est dirigé à travers cette fenêtre ;
• - le moyen de détection est constitué :
• . soit de préférence par un faisceau lumineux, parallèle au plan de la nappe et orthogonal aux fils en déplacement, disposé au voisinage de la pointe des dents et qui de préférence traverse les fenêtres ménagées dans celles-ci,
• . soit par un fil détecteur, disposé de la même manière, mais porté à un potentiel électrique élevé ou parcouru par un courant haute fréquence, de sorte que ce fil, sous l'effet d'un contact avec un fil textile à contrôler, détendu ou cassé, se décharge, pour ainsi commander l'arrêt du métier ou le déclenchement du système d'alarme ;
• - le rayon lumineux traverse des fenêtres ménagées dans les dents, puis est capté par un organe tel qu'une lentille réceptrice photo-sensible, soit directement, soit après réflexion et retraversée desdites fenêtres ; cet organe récepteur est associé au moyen de commande de l'arrêt du métier ou du déclenchement du signal d'alarme ;
• - l'entredent permet juste le passage d'un noeud, afin de réduire au maximum le débit d'air nécessaire et de bien canaliser le flux vers la pointe des dents ;
• - le dispositif détecteur de l'invention forme simultanément peigne diviseur d'un métier à tricoter chaîne.

Advantageously, in practice:

• - The characteristic teeth have a window placed in the area located towards the tip of the tooth and the detection means is directed through this window;
• - the detection means consists of:
• . either preferably by a light beam, parallel to the plane of the sheet and orthogonal to the moving wires, arranged in the vicinity of the tips of the teeth and which preferably passes through the windows formed therein,
• . either by a sensor wire, arranged in the same way, but brought to a high electrical potential or traversed by a high frequency current, so that this wire, under the effect of contact with a textile wire to be checked, relaxed or broken, discharged, thereby controlling the shutdown of the loom or the triggering of the alarm system;
• - The light beam passes through windows made in the teeth, then is picked up by a member such as a photo-sensitive receiving lens, either directly or after reflection and through said windows; this receiving member is associated with the means for controlling the stop of the loom or the triggering of the alarm signal;
• - the entry allows just the passage of a knot, in order to minimize the necessary air flow and to properly channel the flow towards the tips of the teeth;
• - The detector device of the invention simultaneously forms a divider comb of a warp knitting loom.

In a variant, the teeth are full and the incident and reflected beams of the detection member or the detector wire are either on the same side of the tooth, or on either side thereof, but in above the tablecloth plane.

• La figure 1 est une vue perspective sommaire de la partie fonctionnelle, pour l'invention, d'un métier à tricoter chaîne.
• La figure 2 est une vue en coupe du dispositif de détection conforme à l'invention.
• La figure 3 est une vue de dessus montrant la succession des dents parallèles caractéristiques.
• La figure 4 est une représentation sommaire d'une version perfectionnée d'un dispositif détecteur de l'invention.

The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the embodiment which follows, given by way of non-limiting example, in support of the appended figures.

• Figure 1 is a summary perspective view of the functional part, for the invention, of a warp knitting machine.
• Figure 2 is a sectional view of the detection device according to the invention.
• Figure 3 is a top view showing the succession of characteristic parallel teeth.
• Figure 4 is a summary representation of an improved version of a detector device of the invention.

As we know (see Figure 1), a warp knitting machine consists of two or more beams (1) from which run sheets of parallel threads (2) passing respectively in order over two stitches (3) and (4) between which a dividing comb (5) is disposed. The tablecloth then passes over a tension bar (6), then arrives from there to the passettes (7) of the passette bar (8) to be knitted. The whole is integral with the building of the trade.

According to the characteristic of the invention, the dividing comb (5) comprises a plurality of teeth (10) regularly spaced as a function of the gauge of the dimension of a node and parallel to each other. Each individual wire designated by the reference (11) passes between two successive teeth (10,12,13, 14) (see Figure 3). Thus, in a known manner, the teeth position the wires together to prevent them from mixing during movement.

According to the characteristic of the invention, the teeth (10,12,13,14) are fixed by their base (15) in a common block (16) with several teeth, forming a comb holder, for example made of plastic or lead. The teeth (10), made of sheet steel or any other metal resistant to abrasion, comprise in known manner at their points (17) a small orifice (18) through which passes a steel wire intended to facilitate placing the wires (11) between the teeth when threading.

• - d'une part, au voisinage de la pointe (17), une fenêtre (20) ;
• - d'autre part, à la base (15), un ajutage destiné à diriger un flux d'air surpressé vers la pointe (17) de chacune des dents.

According to the invention, each comb tooth (10) has:

• - on the one hand, in the vicinity of the point (17), a window (20);
• - on the other hand, at the base (15), a nozzle intended to direct a flow of pressurized air towards the point (17) of each of the teeth.

To do this, the comb holder (16) is mounted on a tubular support (21) supplied with compressed air, at a pressure for example of the order of one to several decimetres of water column. This support (21) is split over its entire length and this slot constitutes with the teeth (12, 13) of the comb the interdental blow nozzle. Thus, this characteristic opening (22) is as small as possible, and channels all the air flow represented by dotted lines towards the point (17) of the teeth (10) and more precisely towards the window (20). It is this flow which moves the broken or relaxed wire (11), and causes it to excite the detector.

According to a characteristic of the invention, the detection system comprises a box (23) comprising a diode (or a laser) intended to emit through a projection lens (24) a light beam (25) which thus passes through the tunnel formed by the set of windows (20), successive teeth (10-14) parallel. When this light ray (25) has passed through all of the lights (20), it arrives on a mirror (26), for example of the retro-reflector type, to reflect and cross again these same windows (20) to come onto a another lens (27) associated with a receiver. The system includes a signal amplifier (28) which is itself associated with the control (29) for stopping the loom or the alarm system.

When a wire (11) is slack or broken, under the effect of the air flow which passes through the opening (22) and which is directed towards the window (20), this wire (11) broken or slackened is lifted, then passes in front of the window (20) and thus interrupts the light beam (25). This detected interruption and the signal amplified by (28) triggers in (29) either the shutdown of the loom, or an alarm system.

In an advantageous variant, the nozzle (22) is not placed exactly under the tooth but in the immediate vicinity thereof and as provided in the definition at its base. As before, the air flow is directed towards the tip of the tooth. This solution avoids clogging of the nozzle and the gap between two teeth.

In another variant, the light beam (25) is no longer reflected at (26) but is detected directly by a cell similar to (27) arranged in place of the mirror (26). This solution is more suited to large width knitting looms, that is 2.50 m and more wide.

Finally, as already said, the light beam or the detector wire can be placed in the immediate vicinity of the tip of the teeth and slightly outside thereof. This solution then makes it possible to use standard tooth combs.

• - par rapport au dispositif rappelé dans le préambule avec rayon lumineux :
• . sa simplicité de construction,
• . l'augmentation de la probabilité de la détection ;
• - par rapport au détecteur mécanique :
• . l'absence de problème d'enfilage supplémentaire, puisque le dispositif se substitue au peigne diviseur existant,
• . un montage facile sur le métier par simple substitution au peigne (5) classique,
• . l'absence de modification du parcours du fil, donc l'absence d'augmentation des tensions ;
• . l'absence d'augmentation du coût de main d'oeuvre
• . et une compensation des sous-tensions se produisant en particulier sur les fils de lisière, ce qui permet une excellente régularisation des tensions en lisière, ce que l'on ne savait obtenir économiquement jusqu'alors.

The system for detecting the presence of an individual wire according to the invention has many advantages compared to the systems marketed to date. We can cite :

• - compared to the device mentioned in the preamble with light beam:
• . its simplicity of construction,
• . increasing the probability of detection;
• - compared to the mechanical detector:
• . the absence of any additional threading problem, since the device replaces the existing dividing comb,
• . easy mounting on the loom by simply replacing the conventional comb (5),
• . the absence of modification of the course of the thread, therefore the absence of increase in tensions;
• . no increase in labor cost
• . and undervoltage compensation occurs health in particular on the selvedge threads, which allows an excellent regularization of the selvedge tensions, which we did not know how to obtain economically until then.

In this way, these devices can be used successfully, not only in the warp knitting looms, but also in all other devices in which it is necessary to monitor the plies of parallel threads in movement, such as the weaving looms, the beams, gluing machines, warping machines.

Claims (8)

1. A device for detecting the presence of a yarn (11) in a lap (2) of parallel yarns, consisting in:

- means (1, 3, 4) for advancing the lap (2) of a parallel yarns (11);

- a means disposed to one side of, and in the vicinity of the advancing lap (2), for detecting the presence of a yarn (11) away from the lap (2) by a blowing means disposed to the other side of this lap (2);

- a means (28, 29), controlled by the detecting means, for stopping the advancing means of for triggering off an alarm system, characterized:

- that it comprises, in a known manner, a plurality of parallel comb teeth (10, 12, 13, 14), between which the advancing yarns (11) pass,

- and that the blowing means (27) is placed at the base (15) of said teeth (10) and direct the flow of air towards the tip (17) of these teeth (10).

2. Detecting device according to claim 1, wherein the teeth (10) comprise a window (20) placed in the zone located towards the tip (17) of the tooth (10) and that the detecting means (25) is directed through this window (20).

3. Detecting device according to claims 1 and 2, wherein the detecting means is constituted by a wire electrostatically charged, disposed in the vicinity of the tip (10) of the tooth (10).

4. Detecting device according to claims 1 and 2, wherein the detecting means is constituted by a light beam (25), parallel to the plane of the lap (2) and at right angles to the advancing parallel yarns (21), which pass through the channel (20) made into the successive teeth (10, 12, 13, 14).

5. Detecting device according to claim 4, wherein the light beam (25) passes through the channel of windows (20) made in the successive teeth (10, 12, 13, 14), then is reflected on a mirror (26), then passes through this same channel (20), then is received by a receiver (27) associated with the controlling means (28, 29) for stopping the machine or triggering the alarm system.

6. Detecting device according to any claims 1 to 5, wherein the parallel teeth (10, 12, 13, 14) are spaced apart of the dimension of a knot.

7. Detecting device according to any claims 1 to 6, wherein comb serves as the divider (5) of a warp knitting machine.

8. Warp knitting machine comprising a detecting device according to any claims 1 to 7.

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