FR2784697A1 - Assembly for pile yarn tension and yarn break detection has number of elastic springs for yarn guide eyelets and light beams which are cut by their upper ends on yarn break for automatic loom stop - Google Patents

Abstract

An apparatus to monitor pile yarn tension and breakage, at a loom for weaving patterned double velvets, has an assembly of horizontal and parallel guides under a grid of fixed and parallel bars. The guides are separated by gaps, with vertical elastic springs through them in rows, with their lower ends secured to a support mounting and their upper ends at the eyelets. The apparatus to monitor pile yarn tension and breakage, at a loom for weaving patterned double velvets, has an assembly of horizontal and parallel guides (11) under a grid (5) of fixed and parallel bars. The guides are separated by gaps (19), with vertical elastic springs (21) through them in rows, with their lower ends (24) secured to a support mounting (12) and their upper ends (22) at the eyelets. Each eyelet (23) carries a pile yarn (3), to be held normally at a level over the guide assembly (11). The optical monitor system gives light beams (27) parallel to the guides (11), to detect the presence of any eyelet (23) which has been released by a broken pile yarn (3) and automatically stop the loom. The guide assembly (11) has alternating guides at upper and lower height levels in a crenellated structure, with the light beams (27) passing through the indentations, and between two successive rows of elastic springs (21). The upper end of each elastic spring (21) has a member (22) which cuts through a light beam (27) in the event of a pile yarn (3) break at its eyelet (23). The light beams (27) are generated by laser units. The height (F2) of the guides (11) is controlled, to be moved up and down in relation to a fixed frame, to set the height level of the yarn break detection action. The height level (F1) of the lower support (12), for the lower ends of the elastic springs (21), is adjusted up and down in relation to the fixed frame, to set the tension applied to the pile yarns (3). The optical detection system is linked to an electronic unit which is connected to the loom stop control and also to a blinking visual display to indicate a pile yarn (3) breakage.

Description

 The present invention relates to the weaving of shaped velvet, and its subject is a device for tensioning and detecting breakage of the pile threads forming the velvet, a device also known as a "pile breaker".

 Conventionally, a fabric is formed by two essential elements: the warp and the weft. The warp is made up of a series of threads running parallel to the length of the fabric, and it determines the length and width of the fabric; it is she who moves to obtain the material.

The frame is made up of threads perpendicular to the warp, which cross the warp threads or are inserted in the warp after each movement of the warp.

 The different combinations of entanglement or crossing of the warp with the weft, called weaves, produce fabrics with different aspects from each other. We can distinguish five fundamental genres: taffeta, twill, satin, velvet, English gauze. As regards the invention, we will focus exclusively on shaped velvet, and more particularly on shaped double piece velvet.

 The shaped double piece velvet is obtained by the simultaneous weaving of two independent pieces of fabric, one above the other, initially linked to each other by pile threads which form the velvet of each of them. 'they. The manufacture of this type of velvet requires, in addition to the weaving means of the warp and the weft which form the pieces of upper and lower fabric, means of insertion of the pile threads.

For this purpose, organs called canters support coils of pile thread, which can be 3000 to 5000. The shaped is obtained by a Jacquard mechanism, each pile thread being taken in a mesh of the mechanism selected according to the drawing fixed on pique paper. Each time the pile threads are selected, the lower part is linked to the upper part by the selected threads. The fabric is then split in two by means of a blade sliding on a transverse rail, that is to say oriented in the direction of the weft. This blade goes right in the middle of the two pieces, and comes to cut the hairs at mid-height. This operation results in separating the two pieces with velvet on each of them.

 The weaving of shaped double-piece velvet, according to the principle which has just been recalled, remains a very delicate operation, in particular because, the pile threads being selected independently of each other, they must be delivered separately and not not all are advancing at the same speed, hence the utility of the creels and of tension control means of the pile threads, the weaving tension being lower than the tension necessary to unwind a spool.

 In a conventional loom for weaving shaped velvet, as illustrated schematically in Figure 1 of the accompanying drawing, the canters 1 receive a multiplicity of coils 2, which allow the delivery and independent advance of the different pile threads 3. All these wires pass under a vertically movable crossbar 4, called the hair donor, which periodically descends along the arrow F in order to unwind the coils 2. The pile wires 3 then pass over a grid formed of fixed equidistant parallel bars 5, before d 'be directed to the means of insertion of these son. Between two consecutive bars, each pile wire 3 passes over a metallic vertical jumper 6, suspended from this wire 3 and engaged on horizontal guide 7, also metallic and connected to an electrical relay controlling the stopping of the loom. Under the set of jumpers 6 and guides 7 extends a metallic horizontal plate 8. When the hair donor 4 goes down, the jumpers 6 go up until the associated pile wire 3 is horizontal, and the coils 2 then unwind, if their thread 3 is called. Certain coils 2 will not be unwound, because the wires 3 of these are little consumed or are not consumed at all; the corresponding jumpers 6 will therefore not reach their high position. The “hair-breaker” device with jumpers 6 thus performs its first function, which is to tension each pile thread 3 at the weaving tension.

 However, already in this first function, the current "puzzler" is not entirely satisfactory.

 Indeed, the tension of the pile son 3 being ensured by means of the jumpers 6 suspended from each pile wire, this tension depends on the weight of the jumpers. Each rider having a mass of about 2 grams, the weight of the riders is not always optimum and it happens that the tension of the pile threads is too low; in this case, during weaving, the pile threads are floating, and this results in the manufacture of a fabric of poor quality. To avoid this problem, additional jumpers must be added to the pile wires. Given the very high number of pile threads, this operation takes time and penalizes production.

 Sometimes the amount of wire on a spool 2, friction, vibrations, etc ... imply that a spool 2 will unwind more than it should. The jumper 6 then comes into contact with the plate 8 and needlessly stops the loom.

 In addition, depending on whether the design represented by the velvet covers a more or less significant part of the surface of the fabric, the height of the bristles between the two pieces of fabric varies. Indeed the tension of the pile threads tends to bring the two upper and lower chains closer. The "puzzler" does not allow to adapt the tension to the design that is woven on the loom (except to change the jumpers).

 Finally, the silk, viscose or synthetic pile threads are very fragile, and the accelerations undergone by the threads as well as the rebounds of the jumpers create shocks which can break these threads. The current solution therefore does not respond to the dynamic problems encountered in particular for high rates.

The "hair breaker" is also a device which detects the breakage of a pile thread, and then automatically stops the loom, according to the principle illustrated in FIG. 1: when a pile thread 3 ′ breaks, the metal jumper 6 ', which is suspended from this broken wire 3', falls and comes into contact at its lower end, at a point 9, with the metal plate 8. This results in the closing of an electrical circuit passing through the guide 7, the jumper 6 ′ and the plate 8, this causing, by means of a relay, the stopping of the loom. This system is very simple in design, but it is not always reliable, for the following reasons:
-Presence of talc, or other dusty medium, on the parts
forming electrical contacts, preventing the closing of the
circuit.

- Creation of sparks at the contacts, without closing
frank of the circuit, so that the trade is not stopped.

 -Embgement of the riders.

 -Inopportune arrests because of relaxed, but not broken wires.

 In fact, the use of the principle of closing an electrical contact is not suitable for such conditions.

These drawbacks of a current “hair-breaker” are further amplified, in the case of a shaped velvet loom working at a high rate, which can be two to three times greater than that of a traditional loom. This is particularly the case of the weaving loom subject to the French patent? 9507794/2735796 of June 23, 1995 on behalf of
Applicant. For this kind of profession, the problems linked to the "hair-breaker" must be absolutely resolved; in particular :
-The weaving tension of the pile threads must be controlled, in order to
to be able to be modified and to adapt to the weaving of
different designs.

-The "hair-breaker" must be adapted to high rates, by
example of around 300 strokes per minute (while these
are traditionally around 100 strokes per minute).

-The cessation of the trade, in the event of a broken thread, must be
instantaneous.

- Repair times for broken wires must be
same or less than the current solution.

 The object of the present invention is therefore to provide an improved "hair-breaker" device, suitable for weaving machines of shaped velvet which operate at high rates, and particularly effective and reliable both for maintaining the weaving tension of the pile threads, with the possibility of adjusting this tension, only for the detection of the breakage of any one of the pile threads, this detection should in particular not be disturbed by the possible presence of talc or dust, and also avoiding any untimely stops of the loom.

 To this end, the subject of the invention is essentially a device for tensioning and detecting breakage of the pile threads, for weaving shaped velvet, more particularly shaped double piece velvet, obtained with pile threads which are unwound independently others of a multiplicity of coils supported by creels, all the pile threads passing under a vertically movable bar or pile donor, then on a grid formed of fixed parallel bars, this device being characterized in that it comprises, below said grid, a set of parallel horizontal guides, separated by interstices crossed vertically by elastic bands, arranged in rows, the lower ends of which are attached to a fixing support, and the upper ends of which are linked to eyelets respective, each eyelet being crossed by a pile wire which normally maintains it in height above the assembly d e guides, optical detection means emitting light beams parallel to the guides being provided to detect the displacement of any eyelet released by the breakage of the corresponding pile thread, and to then automatically control the stopping of the loom.

 Thus, the invention provides a "hair breaker" in which the tension of the hair threads is ensured by a multiplicity of elastic bands, each linked to an eyelet crossed by a hair thread, and in which the detection of breakage d '' a pile thread is produced by an optical system, without resorting to an electrical contact principle, each elastic being capable of bringing and maintaining the associated eyelet, released by the breakage of the corresponding thread, in an area where it cuts the 'one of the light beams, thus causing a photoelectric type detection which, even, controls the stopping of the loom.

 In a preferred embodiment of the "hair-breaker" object of the invention, the set of guides comprises an alternation of guides of greater height and of guides of smaller height, giving this assembly a profile in slots, the optical detection means being arranged so that their light beams are located inside the slots formed by these guides, each beam also lying between two consecutive rows of elastic bands. Advantageously, the upper end of each elastic band is attached to the associated eyelet by a ligature, which cuts the path of an adjacent light beam during the breakage of the pile wire passing through the eyelet considered. Thus, the guides make it possible to direct and receive, in the event of breakage of a pile thread, the eyelet and its ligature, by bringing them along the path of the light beam, which is common to two adjacent rows of elastic bands and of carnations. Preferably, each light beam, parallel to said guides, is a laser beam, the optical detection means comprising for this purpose, towards one end of the set of guides, a series of laser emitters.

The corresponding receivers, arranged towards the other end of the set of guides, can be phototransistors.

 In an advantageous embodiment, means are provided for the height adjustment of the set of guides, relative to a fixed frame, to allow the detection level to be adjusted.

Advantageously, other similar means are provided for adjusting the height, relative to the same fixed frame, of the fixing support to which the lower ends of the elastic bands are attached, this in order to also adjust the weaving tension of the pile threads. .

 According to a preferred embodiment, the optical detection means are connected to an electronic unit which is itself connected not only to a command to stop the loom, but also to at least one signaling member, such as '' an indicator light, flashing for example in the event of detection of the breakage of a pile thread.

 On the whole, we thus obtain a "hair-breaker" which has numerous technical and human advantages.

Thus, the use of elastic bands to ensure the tension of the pile threads already constitutes in itself a particularly advantageous solution, from various points of view:
-The use of elastic bands eliminates stopping
untimely loom because, if a spool of pile thread
unwinds more than it should, the corresponding elastic
relaxes and the force on the coil decreases. Elastics
thus adapt to each coil.

-The elastic bands, all attached to the same fixing support,
allow quick adjustment of the weaving tension, to
all the pile threads, adjusting only the tension
of these elastic bands, the advantage of this adjustment being to optimize the
pile height, whatever the pattern of the velvet. The
hair height adjustment required, until now, a
long intervention and considerable know-how, both
parameters influencing the tension of the pile threads are
numerous.

-Each elastic allows to maintain the associated eyelet in
permanent contact with the corresponding pile thread. We
thus reduces the shocks and stresses on this wire, when
is used by the loom.

-Despite their high number, the elastics constitute
simple and low-cost organs, making the solution the object of
the particularly economical invention.

 The use of optical means, in combination with the set of elastic bands, with breakage detection by cutting a light beam, also constitutes a particularly suitable and reliable solution, operating without electrical contact, and thus avoiding the problems due to the presence of talc, dust and moisture in the environment. In particular, the use of laser beams allows detection over a long distance, the coherence of each beam allowing its precise passage between the adjacent rows of elastic bands, avoiding interference with the various optical detectors. The detection of a beam cut, therefore of breakage of a thread, by these means is instantaneous, and also almost instantaneously stops the weaving loom. In addition, these means are relatively economical, since each laser beam is common to two rows of elastic bands and eyelets, which limits the necessary number of transmitters and detectors.

The invention also provides a series of advantages concerning the tasks to be performed by the operators concerned (weavers, garages):
Thus, by providing for the triggering of a characteristic light signal, such as the flashing of an indicator, upon detection of the breakage of a pile thread, the device immediately warns the operators of a stopping of the loom. . In addition, during the breakage of a pile wire, the concerned beam will cause the eyelet and / or the ligature fallen on its path to flicker, which allows a quick visual identification of the broken wire. The very principle of the "hair-breaker" therefore provides the operator with precious help in locating a broken wire, on which it will be necessary to intervene. All this represents a simplification of the tasks, as well as a saving of time and productivity. The invention also makes it possible to reduce the mental load of the weavers, since the monitoring of defects linked to non-detection can be reduced. The work of the garages is also simplified, when changing the pattern, because it becomes very easy to adjust the pile height.

 In total, the solution object of the invention thus provides not only a gain in productivity, but also an increase in the quality of the fabric produced.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended diagrammatic drawing representing, by way of example, an embodiment of this tensioning and wire breakage detection device pile, for weaving shaped velvet:
Figure 1 (already mentioned) is a block diagram of a "hair-breaker" of the prior art;
Figure 2 is an overall front view, very simplified, of a "hair-breaker" according to the present invention;
Figure 3 is a partial detail view, in plan from above, of the "hair-breaker" of Figure 2;
Figure 4 is a side view, in section, of this "hair-breaker";
Figure 5 is a front view, on an enlarged scale, showing the detail of an eyelet of this "hair-breaker" and of its connection with the associated elastic;
Figure 6 is a side view, corresponding to the front view of Figure 5.

 The "hair-breaker", shown as a whole in FIG. 2, comprises two vertical fixing feet 10, forming a frame, between which are fixed, at a higher level, a set of horizontal guides 11 and, at an intermediate level, a horizontal fixing support 12, for elastic assemblies described below. The guides 11 are fixed by screw means 13, passing through oblong holes 14 in the fixing feet 10, to allow the height of these guides 11 to be adjusted, the screw means 13 may include a threaded rod and nuts-see also figure 3.

The support 12 is also fixed by screw means, passing through oblong holes 15 in the fixing feet 10, to allow the height of this support 12 to be adjusted, and consequently to adjust the weaving tension of the pile threads. Said support 12 comprises a horizontal plate 16, surmounting two parallel benefits 17 the ends of which are fixed in an adjustable manner, as has just been indicated, to the fixing feet 10-see also FIG. 4.

 In a known manner, analogous to what is shown in FIG. 1, the pile wires 3, coming from the multiple coils 2 of the edges 1, pass first under a vertically movable pile donor 4, then on a grid 5 formed of Equidistant parallel bars, which here overcomes the set of horizontal guides 11, and is located under the path of the warp threads 18. This set includes parallel guides 11, alternately of greater height and of smaller height, which give the 'together a slot profile, clearly visible in Figure 4.

Interstices 19 are formed, by means of spacers 20, between the horizontal guides 11 consecutive, in parallel vertical planes.

 For each pile wire 3, an elastic band 21 is provided, linked by a tie 22 to an eyelet 23. The elastic band 21 extends vertically, and it passes through one of the interstices 19, so that the corresponding eyelet 23 is normally located above the guides 11, but below the grid 5, this eyelet 23 being traversed by the associated pile wire 3. The lower end of the elastic 21 is attached at a point 24 of the plate 16, belonging to the fixing support 12. Figures 5 and 6 show the detail of an eyelet 23 and the ligature 22, ensuring its connection with the upper end of the associated elastic 21.

 The device comprises, as a whole, n rows of N eyelets 23 and elastic bands 21, for example 16 rows of 165 eyelets and elastic bands, each row being located in correspondence with the middle of the free space between two consecutive bars of the grid 5, over which the pile threads pass 3.

 Referring more particularly to FIG. 3, the device also comprises, towards one end of the set of guides 11, a series of laser emitters 25, carried by a common support 26 attached to one of the fixing feet 10 The emitters 25 are arranged so as to create laser beams 27 parallel to the guides 11, and located in the slots formed by these guides 11 (see FIG. 4). Each laser beam 27 is thus located between two consecutive rows of elastic bands 21.

 At the end of the set of guides 11, opposite the laser emitters 25, there is provided a corresponding series of photoelectric receivers 28, of the phototransistor type, symbolized on the left side of FIG. 3. Each receiver 28 is thus arranged on the path of one of the laser beams 27. For reasons of clarity, FIG. 2 indicates neither the elastic bands, nor the laser transmitters, nor the receivers which have just been mentioned.

 The laser transmitters 25 and the corresponding receivers 28 are electrically connected to an electronic unit 29, itself electrically connected to a stop control 30 of the loom, as well as to a signaling member 31, in particular produced in the form an indicator light placed in a place where it is clearly visible.

 In normal operation, each elastic 21 associated with an eyelet 23 ensures the return of the corresponding pile wire 3, with a tension which is a function of the elongation of this elastic 21. All the eyelets 23 are then maintained above the set of guides 11, therefore also above the laser beams 27. The height adjustment of the fixing support 12, along arrow F1, enabled by the oblong holes 15, makes it possible to simultaneously adjust the tension of all the elastic bands 21 , and thus adjust the weaving tension of the pile threads 3, as required.

Under normal operating conditions, each laser beam 27 passes between the elastic bands 21 and strikes the photoelectric receiver 28 which corresponds to it. The electronic unit 29, while noting that all the receivers 28 detect a laser beam 27, authorizes the continuation of the operation of the loom.

 When a pile wire 3 is broken, as illustrated in the left part of FIG. 4, the corresponding eyelet 23 is no longer held in height by the wire 3 and, pulled by its elastic band 21, it falls into the slot. formed between the adjacent guides 11, and reaches a final retaining position, in which this eyelet 23 and its ligature 22 intersect the path of the laser beam 27 positioned in this slot. The interruption of this beam 27 is detected immediately by the corresponding photoelectric receiver 28, which is also immediately noted by the electronic unit 29. The latter then sends a signal to the stop command 30, so that the loom is immediately stopped, in order to allow the necessary repair. Simultaneously, the electronic unit 29 activates the signaling member 31, which manifests itself in particular by a flashing of an indicator light, such a light signal warning operators of a shutdown of the trade. In addition, during the breakage of a pile wire 3, the laser beam 27 concerned will cause the eyelet 23 or its ligature 22 to flicker, being in the path of this beam 27. The broken wire 3 can thus be identified visually by an operator, without the need to bend down to look for it (as was the case with traditional "puzzles"), which also helps to facilitate and accelerate manual intervention in the event of breakage.

 The height adjustment of the set of guides 11, along arrow F2, enabled by the oblong holes 14, makes it possible to adjust the detection threshold, the detection being done anyway without contact, which avoids problems caused by the environment. ambient (talc, dust, ...).

 It goes without saying that the invention is not limited to the only embodiment of this device for tensioning and detecting breakage of pile threads, for weaving shaped velvet, which has been described above by way of description. 'example; on the contrary, it embraces all the variants respecting the same principle, whatever the number of horizontal guides, the detail of the fixing and adjustment means, or the shape given to the means for signaling the breakage of a wire, in particular. of hair.

Claims (7)

 1-Device for tensioning and detecting breakage of the pile threads, for weaving shaped velvet, more particularly shaped double piece velvet, obtained with pile threads (3) which unwinds independently of one another by a multiplicity of coils (2) supported by creels (1), all the pile wires (3) passing under a bar (4) vertically movable (arrow F) or hair donor, then on a grid formed by fixed parallel bars (5) , characterized in that it comprises, below said grid (5), a set of parallel horizontal guides (11), separated by interstices (19) traversed vertically by elastic bands (21), arranged in rows, of which the lower ends (24) are attached to a fixing support (12), and the upper ends of which are linked (at 22) to respective eyelets (23), each eyelet (23) being traversed by a pile wire (3 ) which normally keeps it high above The set of guides (11), optical detection means (25, 28) emitting light beams (27) parallel to the guides (11) being provided for detecting the displacement of any eyelet (23) released by the breakage of the wire of pile (3) corresponding, and to then automatically control the stopping of the loom.  2-Device for tensioning and detecting breakage of the pile threads, according to claim 1, characterized in that the set of guides (11) comprises alternating guides (11) of greater height and guides (11) more small height, giving this assembly a crenellated profile, the optical detection means (25,28) being arranged so that their light beams (27) are located inside the crenellations formed by these guides (11), each bundle (27) also lying between two consecutive rows of elastic bands (21).  3-Device for tensioning and detecting breakage of the pile threads, according to claim 1 or 2, characterized in that the upper end of each elastic band (21) is attached to the eyelet (23) associated by a ligature ( 22), which cuts the path of an adjacent light beam (27) when the pile wire (3) breaks through the eyelet (23) in question.  4-Device for tensioning and detecting breakage of the pile threads, according to any one of Claims 1 to 3, characterized in that the optical detection means comprise, towards one end of The set of guides (11), a series of laser emitters (25) which create laser beams (27) parallel to said guides (11).  5-Device for tensioning and detecting breakage of the pile threads, according to any one of Claims 1 to 4, characterized in that means (13,14) are provided for the height adjustment (arrows F2) of the set of guides (11), relative to a fixed frame (10), to allow the detection level to be adjusted.  6-Device for tensioning and detecting breakage of the pile threads according to any one of Claims 1 to 5, characterized in that means (15) are provided for the height adjustment (arrow F1), relative to a fixed frame (10), of the fixing support (12) to which the lower ends of the elastic bands (21) are attached, to allow the weaving tension of the pile threads (3) to be adjusted.  7-Device for tensioning and detecting breakage of the pile threads according to any one of Claims 1 to 6, characterized in that the optical detection means (25, 28) are connected to an electronic unit (29) which is itself connected not only to a stop command (30) of the weaving loom, but also to at least one signaling member (31), such as an indicator light, for example flashing in the event of for detecting the breakage of a pile thread (3).