Textiles: weaving – Stopping – Weft
Patent
1994-04-05
1996-01-02
Falik, Andy
Textiles: weaving
Stopping
Weft
250561, 250571, 139192, D03D 5134
Patent
active
054799651
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for monitoring, preferably arrival monitoring, of the weft, e.g. the weft thread, in a loom of substantially the type in which the weft is driven through the shed with the aid of a jet, preferably a gas jet, e.g. an air jet, and which has a reed which is constructed from a number of lamellae disposed vertically with spacing, and which is pivotal between a first position and a second position and has a longitudinal channel for the weft.
Prior art arrival indicators suffer from an unreliable function which manifests itself primarily in many error signals and in many missed actual error trigger situations. These problems are accentuated particularly in air powered looms, so-called jet looms, which are extraordinarily quick and operate at high speeds such as 20 picks per second, in which event the arrival sensing must be executed during approximately 10-15 per cent of a complete machine cycle (5 per cent of the revolution). This naturally places extreme demands on the indicator itself and the associated electronics, in particular as regards sensitivity and speed. A major inconvenience in prior art arrival indicators is a very high degree of wear, which necessitates replacement of the indicator after short operational lives such as one month.
SUMMARY OF THE INVENTION
The task forming the basis of the present invention is to obviate the drawbacks inherent in prior art arrival indicators to as high a degree as possible.
The present invention realizes an arrival indicator which, with great reliability, may be employed in the most rapid jet looms or air powered looms in that the weft thread is sensed not only during a single instant of time but during a given period of time. This affords: in addition, an effective possibility to distinguish between the passage of some other foreign matter than a weft thread and the presence of the weft thread proper, whereby the risk of confusion is precluded. The apparatus according to the present invention further makes possible monitoring of whether an excessively long weft thread has been blown through the woven fabric and the end has become more or less jumbled at the edge of the fabric. Moreover, the apparatus according to the present invention permits sensing of such threads as have hitherto not been possible to sense in prior art optical indicators, e.g. non-reflective threads. An apparatus according to the present invention will not be subjected to any major degree of wear, whereby the service life of an apparatus according to the present invention has been greatly extended. It is also possible to employ the apparatus according to the present invention for controlling the air emission in the loom, since the indicator or the apparatus according to the present invention sees the entire channel or homogeneously into the entire channel and it thereby becomes possible to establish the exact arrival time of the thread with a very high degree of accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. FIG. 1 schematically illustrates a vector diagram of a machine cycle. FIG. 2 is a side elevation of a reed with an apparatus according to the present invention in different positions during a machine cycle. FIG. 3 is a side elevation of a part of an apparatus according to the present invention. FIG. 4 shows a section taken along the line A--A in FIG. 3. FIG. 5 shows a section taken along the line B--B in FIG. 3. FIG. 6 shows a section taken along the line C--C in FIG. 3. FIG. 7 is a side elevation of the part illustrated in FIG. 3 seen from the opposite side. FIG. 8 is a front elevation of the part of an apparatus according to the present invention illustrated in FIG. 3. FIG. 9 is a schematic diagram of a part of the electronic circuitry in which an apparatus according to the present invention is included. FIG. 10 is a side elevation of a reed with an apparatus according to an
REFERENCES:
patent: 4188981 (1980-02-01), Suekane et al.
patent: 4716942 (1988-01-01), Jensen et al.
patent: 4738284 (1988-04-01), Ishikawa et al.
patent: 5329961 (1994-07-01), Bouvyn et al.
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