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(11) | EP 0 411 181 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Weft yarn detector, particularly for jet looms |
| (57) A pick-up device of a weft thread (6) at its final stage of introduction into the
shed of a loom, particularly for jet looms, comprises a transmitter (2) and a receiver
(3) of electromagnetic heat, the optical axis (14) of which is transversely to the
track of the introduced weft thread (6) and is situated at a distance of at most twenty
times the recounted diameter of the weft thread (6) from a plane passing through beat-up
parts (15) of adjacent dents (7) of the beat-up reed (4). An arrangement is provided for indicating safely the presence of a weft thread (6) fully introduced into the shed of a loom even in case the loom is operating in dusty surroundings, which arrangement is simultaneously adjustable for different widths of the fabric. |
[0001] The invention relates to a pick-up device of a weft thread at its final stage of passage in the shed of the loom, particularly for jet looms with introduction of the weft by a stream of a carrier medium by way of a feeding channel created by shaped parts of dents of the beat-up reed, comprising coaxially arranged mouths of a transmitter and receiver of electromagnetic heat provided between dents of the beat-up reed, whereby the optical axis of said transmitter and receiver is oriented transversely to the track of the introduced weft thread and parallel to beating-up parts of adjacent shaped dents of the beat-up reed.
[0002] Known pick-up devices of weft threads at their final stage of passage in the shed of a jet loom with introduction of the weft thread by an air medium utilizing the optoelectronic principle for detection of the weft thread in the space of the introductory channel are of large dimensions and require in case of a change of the width of the fabric a beat-up reed of the respective width enabling the mounting of the pick-up device of the weft thread between the end of the fabric, up to which place the weft thread is urged to proceed and of the binding thread of the weft waste. Otherwise a prolongation or shortening of the beat-up reed according to the width of the fabric is required. Other known optoelectronic pick-up devices operate on the principle of reflection of transmitted electromagnetic heat from the weft thread and are utilizing optics. They are situated on the slay of the loom and partly influence the track of the air medium causing a turbulence of air and thus possibly also that fine weft materials do not reach their destination. An optoelectronic pick-up device is also known with pick-up elements situated mutually opposite, composed of two pieces requiring a difficult mounting to the loom and problems with fixing a couple of connecting cables. A further known optoelectronic pick-up device has the same shape as dents of the beat-up reed, is of course substantially wider than the gap between individual dents, and light conductors are used for supply of electromagnetic heat to the detection place. The heat source and the receiver are situated on the upper and lower support of dents of the reed. This pick-up device does not allow any change of the weaving width without adjustment of the length of the reed, or without its exchange.
[0003] A common drawback of known pick-up devices of weft threads is mainly their unfavourable position causing a rather unreliable introduction of the weft, particularly in the dusty medium of weaving mills and in case of weaving dusty fabrics.
[0004] Another drawback is that they are highly demanding in manufacture, technology and assembling. A drawback is also the already mentioned requirement of a wearisome adjustment of the beat-up reed in case of a change of the width of the fabric.
[0005] It is an object of this invention to substantially eliminate said drawbacks of pick-up devices of the weft thread at its final stage of introduction, i.e. to improve the reliability of picking up the weft thread and to reduce manufacturing operations and assembling expenses, particularly for jet looms.
[0006] Said object is achieved, according to the present invention, by a pick-up device of a weft thread, particularly for jet looms, where the weft thread is introduced by way of an introductory channel by a stream of a carrier medium, said channel being composed of shaped dents of a beat-up reed and comprising also coaxially arranged mouths of a transmitter and a receiver of electromagnetic heat provided between dents of the beat-up reed, whereby their optical axis is oriented transversely to the track of the weft thread and in parallel to beating-up parts of adjacent dents of the beatup reed, characterized in that the optical axis of the mouth of the transmitter and the receiver of electromagnetic heat is, from the plane passing through beat-up parts of adjacent dents of the beat-up reed, at a distance of at most twenty times the recountable diameter of the introduced weft thread.
[0007] It is advantageous that the transmitter and the receiver of electromagnetic heat are arranged on a pick-up part of a body of the pick-up device in a flat shape situated between dents of the beat-up reed provided with a recess, the shape of which corresponds to the introductory profile of shaped dents of said reed, into which recess the transmitter and the receiver of electromagnetic heat are terminating, whereby a supporting part of the body of the pick-up device is fixed on the slay of the loom.
[0008] It is furthermore advantageous that the pick-up part is disassemblably connected to said supporting part.
[0009] The main advantage of the pick-up device of the weft thread according to this invention is its suitable arrangement securing a reliable picking-up of the weft thread at the final stage of its introduction into the shed even in a dusty surrounding of weaving mills and in the course of weaving dusty fabrics. Another advantage is the reduction of manufacturing, operational and assembling requirements. The pick-up device can be mounted on the loom according to the width of the fabric without any adjustment or replacement of the beat-up reed.
[0010] Examplary embodiments of this invention are shown diagrammatically in the attached drawings, where are
Fig. 1 a sectional view showing the introductory channel and its arrangement on the slay of the loom,
Fig. 2 an elevation of one embodiment of the pick-up device of the weft thread as applied on the loom shown in Fig. 1,
Fig. 3 a top view of the device shown in Fig. 2,
Fig. 4 an elevation of another embodiment of the pick-up device,
Fig. 5 the corresponding top view,
Fig. 6 an elevation of a third embodiment of the pick-up device, and
Fig. 7 the corresponding top view.
[0011] The slay 5 of a loom not shown in detail in Fig. 1 performs a reciprocating swinging movement from an introductory position indicated in Fig. 1 by full lines in direction 9 to a beat-up position indicated in Fig. 1 by dashed lines. The beat-up reed 4 is supported in a slot 16 of the slay 5, the shaped dents of the reed having recesses 8 forming in a system of dents 7 an introductory channel for introduction of the weft thread 6 in the open shed of the loom created by the upper and lower system of warp threads 21 and 22 by an air stream from a main nozzle not shown and from additional nozzles 10 situated along the slay 5 and arranged adjustable in a groove 20. The pick-up device of the weft thread 6 at its final stage of introduction includes a coaxially arranged mouth of a transmitter 2 and of a receiver 3 of electro magnetic heat, for instance within the infrared range which are situated between dents 7 of the beat-up reed 4 whereby the optical axis 14 thereof is parallel to the beat-up parts 15 of adjacent shaped dents 7 of the beat-up reed 4. It is important for functional reasons of the introduced weft thread that the optical axis 14 of the mouth of the transmitter 2 and of the receiver 3 of electromagnetic heat is, from a plane passing through beat-up parts 15 of adjacent dents 7 of the reed 4 at a distance of at most twenty counted over diameters of the introduced weft thread 6. The transmitter 2 and the receiver 3 of electromagnetic heat are advantageously arranged in the pick-up part 11 of the body 1 of the pick-up device. The pick-up part 11 is of flat shape and is situated between dents 7 of the beat-up reed 4. It is provided with a recess 13, the shape of which corresponds to the beat-up profile of shaped dents 7 of the reed 4, particularly with its recesses 8. The transmitter 2 and the receiver 3 of electromagnetic heat are terminating into the recess 13 whereby the supporting part 19 of the body 1 of the pick-up device is fixed on the slay 5 of the loom. This fixing of the body 1 of the pick-up device enables, in the course of weaving, a partial mutual movement of the pick-up part 11 and of adjacent shaped dents 7, causing thereby that the settling of textile dust is prevented, which dust is blown away by the air stream. It is advantageous from the point of view of manufacture and assembling if the pick-up part 11 is connected disassemblably to the supporting part 19 of the body 1 of the pick-up device, for instance by means of screws with countersunk heads not shown.
[0012] Examplary embodiments of the supporting part 19 of the pick-up device of weft threads in the course of the final stage of their passage in the shed of the loom and its fixing on the slay 5 are shown in the attached drawings. In case of the examplary embodiment as shown in Fig. 1, 2, 3 the supporting part 19 of the body 1 of the pick-up device is provided with a supporting extension 12, by means of which it is fixed, together with the beat-up reed 4, in the slot 16 of the slay 5. In another embodiment shown in Fig. 4 and 5 the supporting part 19 of the body 1 of the pick-up device has a slot 18 for fixing on the rear part of the slay 5 by screws. According to a third embodiment shown in Fig. 6 and 7 the supporting part 19 of the body 1 of the pick-up device is provided with a guiding extension 23 for introduction in a slot 20 for auxiliary nozzles 10. In this embodiment the pick-up part 11 of the body 1 of the pick-up device is inserted between shaped dents 7 of the beat-up reed 4 from the front side, representing an alternative to preceding embodiments. Each supporting part 19 of the body 1 of the pick-up device has an opening 17 for fixing a connector not shown for connection of the pick-up device to electrical evaluation circuits of the loom not shown.
[0013] The slay 5 moves in the course of weaving rhythmically from the introductory to the beat-up position and vice versa at each revolution of the loom. The weft thread 6 is introduced at the introductory position into the introduction channel. At the moment the weft thread is moving between the mouth of the transmitter 2 and the receiver 3 of electromagnetic heating, which takes place at its introduction or at the movement of the slay to its beat-up position, the intensity of electromagnetic heating is changed, creating an electrical impulse which after processing by electronics of the pick-up device and of evaluation circuits of the loom enables a subsequent operation of the loom. In case said impulse is lacking, the evaluation circuits stop the loom for absence of the weft thread 6, that is, the weft thread has not finished its supposed course.
1. Pick-up device of a weft thread, particularly for jet looms, where the weft thread
is introduced by way of an introductory channel by a stream of a carrier medium, said
channel being composed of shaped dents of a beat-up reed and comprising also coaxially
arranged mouths of a transmitter and a receiver of electromagnetic heat provided
between dents of the beat-up reed, whereby their optical axis is oriented transversely
to the track of the weft thread and in parallel to beating-up parts of adjacent dents
of the beat-up reed, characterized in that the optical axis (14) of the mouth of the
transmitter (2) and the receiver (3) of electromagnetic heat is, from the plane passing
through beat-up parts (15) of adjacent dents (7) of the beat-up reed (4), at a distance
of at most twenty times the recountable diameter of the introduced weft thread (6).
2. Pick-up device according to claim 1, characterized in that the transmitter (2)
and the receiver (3) of electromagnetic heat are arranged on a pick-up part (11)
of a body (1) of the pick-up device in a flat shape situated between dents (7) of
the beat-up reed (4) provided with a recess (13), the shape of which corresponds to
the introductory profile of shaped dents (7) of said reed (4), into which recess
(13) the transmitter (2) and the receiver (3) of electromagnetic heat are terminating,
whereby a supporting part (19) of the body (1) of the pick-up device is fixed on
the slay (5) of the loom.
3. Pick-up device according to claim 2, characterized in that the pick-up part (11)
is disassemblably connected to said supporting part (19).