EP1880049A1

EP1880049A1 - Apparatus and method for in-line reading and control of warp threads in a loom

Info

Publication number: EP1880049A1
Application number: EP06755868A
Authority: EP
Inventors: Pietro Gironi
Original assignee: Gironi System Srl
Current assignee: Gironi System Srl
Priority date: 2005-04-29
Filing date: 2006-04-24
Publication date: 2008-01-23
Also published as: ITFI20050080A1; IL186848A0; WO2006117673A1; JP2008539338A; CN101184878A; KR20080011309A

Abstract

Apparatus and method for reading and controlling warp threads in a loom, comprising the use of a device (14, 16) for the reading and acquisition of images, and the comparison between the acquired images and one or more predetermined samples to determine at least one state of defect in the work cycle based on the result of said comparison in order to instantly cut off the operation of the loom in response to the determined defect.

Description

DESCRIPTION

APPARATUS AND METHOD FOR IN-LINE KESADING AND COMTROL OF WARP THREADS IN A LOOM

Technical Field

The object of the present invention is an apparatus for controlling the warp threads during the manufacturing of a fabric on a loom. Background art As well known, a fabric is obtained by interweaving warp threads - fed by corresponding beams and disposed parallel along the loom - with weft threads which are made to pass transverse to the warp by lifting one or more warp threads relative to the others by means of suitable devices, so- called heddles, so as to create a channel for the passage of a weft-carrying shuttle.

The interweaving takes place according to a scheme, so- called texture, which actually indicates the interweaving pattern and corresponds to the repetition of the warp threads jackings. The formation of the fabric in a loom, therefore, takes place with a continuous cycle which, by following the sequence indicated in the interweaving pattern consists of: shed formation due to warp-threads jackings; opening of a reed; insertion of wefts thread; and, finally, closing and shooting of the reed.

At present, control devices are known, so-called warp stops and weft stops, which cut off the loom's operation upon the occurrence of anomalies, due to the breaking of threads or wefts, which breaking, if not signalled, would impair the quality of the work by generating defects and imperfections .

The control of warp threads has been performed in the past by means of drop wires disposed astride of stretched warp threads and crossed by rod formed by two toothed plates reciprocating in opposite direction so that, in case of thread's breaking, the corresponding drop wires would, by falling down, fix in between the teeth of the plates thereby signalling the failure of the thread. Recently, the mechanical drop wires have been replaced by ones being electrically connected in such a way as to cause an electrical signal for the shut down of the loom. Still more recently, in place of the drop wires, laser sensors have been used positioned on the sides and at right angles of the warp threads to define a control line, which sensors are able to "read" the passage of a broken thread crossing the line as it falls.

However, this solution is applicable only to rigid yarns which can actually cut off the control line when they fall. These known solutions have a drawback in that - in particular when using non-rigid yarns - the signalling of the thread' s fall occurs with some delay or does not occur at all.

It occurs frequently, for example, that a thread would "shred" or break by winding up over an adjacent thread without falling down. In such case, the drop wire and sensor devices are both ineffective.

As a result, the fabric outputting of the loom may have several types of defects which, depending on their extension, are either mended with a darning, or classified as a defect, which leads to a down-grading of the roll of finished product.

Such defects, more or less mendable, may consist, for example, in the failure of a thread, the formation of two or more warp threads being wound up, the formation of knots, the formation of vertical scorings or thin-weft regions, and reeding' s faults. Disclosure of the Invention

A first object of the present invention is to overcome the drawbacks of warp-controlling devices of known type. A second object is the possibility of identifying, in a repeatable and reliable manner, the defects that call for the interruption of the cycle and those that imply a different intervention such as a darning or requalification of the fabric. A further object is to provide a continuous or periodic report of dissimilarity in the quality of the fabric under formation with respect to an awaited result. The technical task and the specified objects are substantially achieved by an apparatus and a method for reading and controlling warp threads, comprising the technical characteristics set forth in one or more appended claims .

Further characteristics and advantages of the present invention will appear more clearly from the following indicative, and thus non-limiting, description of a preferred, but nonexclusive, embodiment of the invention with reference to the accompanying drawings, in which:

- Figs. 1, Ia and 2 show a warp-stop device of the prior art for stopping the loom in case of warp threads failure, and a detail of drop wires traditionally used as a shut down means;

- Fig. 3 shows schematically a laser device of the prior art for checking warp threads failures;

- Figs. 4a/4b and 5a/5b show schematically a reading and control device according to the invention, in case of no failure of warp threads and, respectively, of detection of warp threads failure in a loom;

- Fig. 6 shows an example of texture with the interweaving report for the formation of a fabric in a loom; and - Fig. 7 is a detail of the jacking and lowering region of the threads in a preferred embodiment of the apparatus according to the invention.

With reference to Figs. 1 and 2, these illustrate schematically a technical solution of known type in which drop wires 1 are disposed astride of warp threads 2 raised by heddles 10 of the loom to allow the passage of subsequent weft threads 15 which, shot by a reed 11, form a fabric 12.

The drop wires are crossed by a rod made up of two toothed plates 3 driven into reciprocating motion so that, in case of failure of a thread 2' , the corresponding drop wire, by falling down, will become stuck between the teeth ^'4 of the plates thereby signalling the breaking of the thread. Fig. 2 shows a drop wire 1' with metal parts 5, 6 normally separated by an insulator 7 and which are electrically connected in case of thread failure.

Fig. 3 shows the use, according to a known technique, of laser sensors 8 located sideway and orthogonally to the warp threads in order to define a control line 9 - upstream of heddles 10 or between the heddles 10 and the reed 11 - able "to read" the passage of a broken warp thread which crosses said line upon falling down.

Schematically illustrated in Figs. 4 (a, b) and 5 (a, b) is an apparatus according to the invention. The apparatus comprises one or more telecameras 14 (or other image-acquisition device) which, upon use, can be positioned above the reed 11 of the loom over part of or whole the work height. The telecamera is disposed to frame the sequence of jackings of warp threads 2 operated by the loom's heddles according to a predetermined interweaving pattern (Fig. 6) and interfaced with an electronic support 16 for controlling the TV-shots, such as a video board or a processing unit 17, the latter possibly consisting of a personal computer or other data-processing unit.

It is stressed that in different embodiments, the transmission of data from the telecameras 14 to the support 16 and, from this to the unit 17, could be made via cable 18 or in wireless fashion (infrared, optical, radiofrequency or other interface) , and, moreover, also the telecamera 14, the board 16 and the processing unit 17 could be integrated in a same device to meet any application requirements.

At least in correspondence of every warp jacking, the telecamera 14, being provided with suitable optics, carries out one or more shots of images of warp threads (designated by 19 in the figure) controlled by the electronic board 16 and relating, preferably, to a region Ll close and upstream of reed 11, or at a region L2 close and downstream of the reed.

The acquired image is fed to the processing unit 17 to be converted into a code 24, preferably in the form of a bar code and compared with one or more preset sample codes corresponding to the intended configuration of warp threads.

Preferably, the sample codes corresponding to the different and proper configurations of the warp are memorized (e.g., in form of bar codes) after an initial procedure of approval of the fabric in the course of formation, which is operated at the beginning of the work by sampling and memorizing within the board 16 all the jackings relative to the interweaving pattern (four in the case of the interweaving pattern of Fig. 6) , each of which will produce a different code 24. Moreover, the reading of warp threads in the course of jacking may take place by using a solid state light flash

(not shown as being known in the art) which is synchronized with the succession of jackings and images shooting.

Advantageously, the apparatus may be provided with two indicators of final and initial reading 20, 21 disposed at the edges of the fabric, for example on the upper bar 22 of the reed 11.

Preferably, a millimeter scale may also be provided on the bar 22 to facilitate the direct identification of the defect detected by the system on the formed roll. During the operation of the apparatus, a complete analysis of the internal and external warp thread edges, and of the yarn pattern as well, can be performed on every image code, by looking for possible local dissimilarity. The processing of the image - possibly based on tolerance thresholds pre- settable for any type of defect - allows a coding of the detected defects, and it is preferably carried out in the course of a monitoring synchronized with the jackings and repeated over and over again along the reading region, in order to locate the position of the defect and track down every single defect in the fabric under formation. Shown in Figs. 4a, b and 5a, b respectively, is a first example (Fig. 4a) in which the image acquired by the telecamera 14 allows determining the proper code 24, that is, a code corresponding to a condition of absence of defects, and a second example (Fig. 5a) in which the image being read allows determining an "erroneous" code 24' corresponding to the defect "failure" of a warp thread 2' . According to the invention, in response to the determination of the code 24', the processing unit 17 can be programmed for stopping the operation cycle and causing the shutdown of the loom, for example.

Advantageously, it is however possible to preset - on the basis of the desired final quality of the fabric, for example - whether the size and type of the detected defect

(failure, fraying, winding, etc. ) is acceptable or not and, consequently, instead of shutting down the loom, to go on with the work and merely signalling in a report the presence of the defect and possibly its position in view of a darning or a reclassification of the roll of fabric.

The detection of dissimilarity with respect to preset samples can also be carried out, upon every jacking, for any interweaving pattern, or periodically, after a preset number of jackings. It is also possible to provide a display for (continually or periodically) reading from the outside the images, and/or for emitting alarm signals corresponding to one or more detected defects.

In a preferred embodiment, provision is also made for a central server for controlling a plurality of devices, each device being associated with a fabric under formation. In this embodiment, in case of dissimilarity with respect to the sample, the apparatus will be linked with the server that will "decide" a possible intervention based on preset tolerances and criteria, by defining the coordinates for the fabric under formation and the point on the millimeter bas 22, in order to intervene with the darning. Fig. 7 shows a preferred solution of the apparatus according to the invention. In this embodiment provision is made for inserting a bar 25 behind the reed 11 and parallel thereto to achieve only one support plane for the threads 2 in the course of jacking.

This approach makes it possible to avoid possible drawbacks of insufficient reading at regions close to the acquisition field where, without the said bar 25, the threads taking up a higher position would tend to partially or totally hinder the threads at a lower level, thereby determining an apparent condition of error leading the server "to decide" of cutting off the production. The above mentioned drawback derives from the fact that the telecamera 14 is located at some distance above the upper threads and in central position with respect to the width. With this arrangement, the telecamera 14 makes a framing of divergent conical shape, from which some of the lower threads, being offset in width relative to the upper threads, could be excluded.

The bar 25 bring all the threads to the same level in the reading region of the telecamera and overcome, therefore, the above described drawback. It can be seen, therefore, from the foregoing, that the advantages obtained with the invention are, in particular, the suppression or reduction of the traditional warp-stops required in a loom, the ease and rapidity of installation thereof on any loom, the continuous and real-time control of the fabric-forming process, the absence or limitation of elements (the wire drops of traditional warp stops) in direct contact with the warp threads and the possibility of making a complete map of the defects on the formed fabric roll. The invention thus conceived may also be subjected to several modifications and variants all falling within the inventive scope; moreover, all the parts can be replaced by technically equivalent elements.

Claims

1. Apparatus for reading and controlling warp threads in a loom, characterized in that it comprises: at least one device (14, 16) for the reading and acquisition of images of a plurality of warp threads (2, 2' ) during the work cycle on the loom; means (17) of comparison between the acquired images and one or more predetermined samples to determine at least one state of defect in the work cycle based on the result of said comparison; means for instantly cutting off the operation of the loom in response to the revealed defect or for signalling the revealed defect.

2. Apparatus according to claim 1, comprising means for processing the acquired images and converting them into a code (24, 24') being comparable with sample codes.

3. Apparatus according to claim 1, comprising means for synchronizing a succession of acquired images with the jacking movements of the warp threads according to the work cycle.

4. Apparatus according to any of the preceding claims, comprising means to illuminate a region of images reading and acquisition.

5. Apparatus according to claim 4, wherein said lighting means consists of a solid state flash synchronized with the jacking motion of the warp threads.

6. Apparatus according to any of the preceding claims, wherein said means for the reading and acquisition of images (24) comprise one or more telecameras.

7. Apparatus according to any of the preceding claims, wherein said reading and acquisition means comprise an electronic board (16) that can be interfaced with a processing unit (17) .

8. Apparatus according to any of the preceding claims, wherein said means for comparing the acquired images with one or more preset samples, and said means for determining at least one state of defect of the work cycle, comprise a processing unit (17) able to compare the acquired images with one or more samples and draw information therefrom relating to one or more work defects, and comprise also means for correlating the detected defect (s) with one or more interventions to be made on the work cycle of the loom.

9. Apparatus according to any of the preceding claims, comprising elements (20, 21) for delimiting the beginning and end of reading region.

10. Apparatus according to any of the preceding claims, comprising means for displaying the acquired images.

11. Apparatus according to any of the preceding claims, comprising means for emitting an alarm in response to the determination of a work defect.

12. Apparatus according to any of the preceding claims, comprising means for outputting one or more reports about the dissimilarity of the fabric (12) under the course of formation with respect to a preset sample of fabric to be produced.

13. Apparatus according to any of the preceding claims, wherein at least one of said samples consists of the acquired image of an initial length of the fabric (12) under work on the loom.

14. Loom comprising an apparatus according to at least one of claims 1 to 13.

15. Method for the reading and control of the warp threads in a loom, characterized in that it comprises: - at least one phase of reading and acquisition of images relating to a plurality of warp threads (2, 2' ) during the phase of warp jacking;

- a phase of comparison between the acquired images and one or more preset samples; - a phase of determining at least one state of defect in the work cycle based on the comparison result;

- interruption and modification of the loom operation on the basis of the determined defect.

16. Method according to claim 15, wherein provision is made for the transformation of the acquired images into codes

(24, 24') and the comparison thereof with one or more sample codes.

17. Method according to claim 15 or 16, wherein said codes are bar codes.

18. Method according to any claims 15-17, wherein a succession of images acquisitions is synchronized with the motion of warp threads jacking according to the work cycle.

19. Method according to any claims 15-18, wherein provision is made for a phase of correlation between the detected defect (s) and one or more interventions to be carried on the work cycle.

20. Method according to any claims 15-19, wherein provision is made for outputting one or more reports on the dissimilarity of the fabric under formation with respect to one or more preset sample fabrics.

21. Method according to any claims 15-20, wherein at least one of said samples is obtained by acquiring the image of an initial length of the fabric under formation on the loom.

22. Method according to any claims 15-20, wherein said reading is made over a length defined in the region (Ll) of the warp threads comprised between the heddles and the reed.

23. Method according to any claims 15-21, wherein said reading is made over a length defined in the region (L2) of the warp threads comprised between the reed and formed fabric.

24. Computer program, comprising instructions for implementing a method according to at least one of claims 15-23.

25. Program according to claim 24, comprising an electronic chart for correlation between detected defects and corrective and informative interventions.

26. Electronic or optical support for storage of a program according to claim 24 or 25.