Textiles: weaving – Special-type looms – Multiple-shed
Patent
1997-06-19
1999-03-09
Falik, Andy
Textiles: weaving
Special-type looms
Multiple-shed
139450, 139194, D03D 3500, D03D 4734
Patent
active
058787879
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of Technology
This invention relates to a ribbon loom having a weft compensating device.
2. Description of the Prior Art
Ribbon looms of the type stated in the introduction are known in diverse forms, for example from GB-B-2 039 547. The ribbon loom contains, a weft insertion needle, to which is assigned a weft supply device, which has--as viewed in the running direction of the weft--a weft source, a weft braking-device, a weft conveying device, and a weft compensating device. The weft compensating device is formed by a leg spring, which moves back and forth between a first and a second position. In the first position, the leg spring releases the weft for insertion of a weft loop, by means of a weft insertion needle, into a shed. Upon withdrawal of the weft insertion needle from the shed, the leg spring takes up the second position, in which it accepts a weft reserve and finally clamps the weft in a cleft formed with a leaf spring, in order to prevent further conveyance. Upon reinsertion of the weft into the shed, the weft is again tensioned, and the leg spring moves out of the second position into the first position, the weft simultaneously coming free from the clamping leaf spring. This compensating device has the disadvantage that it is relatively sluggish, so that a ribbon loom therewith equipped is limited in its drive speed of rotation, specifically the introduction and extraction of the weft on the braking leaf spring further limiting the efficiency of the ribbon loom.
Ribbon looms with such mechanical compensating devices have the disadvantage that they are limited in their performance, that is, in the maximum speed of rotation up to 2500 revolutions per minute (rpm). If such a ribbon loom is operated at a higher speed of rotation, serious problems arise. The leg springs can break and/or they enter into a critical vibration range, in which the tension of the weft can no longer be controlled. Natural vibrations and inertial forces require a greater spring force, which can become greater than the tear strength of the weft to be processed. As a consequence of the required greater leg spring force, the service life of the latch type weaving needles decreases to 1/2 hour. Moreover, as a consequence of the excessively high weft tension strong interlacing of the ribbons to be produced is caused, and the ribbon cannot be kept at a constant width, the ribbon being narrower, in particular on starting of the ribbon loom. Further, edge wire breaks occur as a consequence of the required excessively high weft tension.
In customary ribbon looms, today all the mesh edge types are produced with latch type weaving needles, also called latch needles. Such latch type weaving needles are suitable only up to speeds of rotation of 2500 rpm. At higher speeds of rotation, breaks occur by the hooks and latches, the latter as a result of the high acceleration upon deflection of the latches. The service lives of the latch type weaving needles at speeds of rotation of 2500 to 4000 rpm are approximately 1 to 4 hours, which is not acceptable in practice.
Known from each of F.R.-A-2 368 561 and U.S. Pat. No. 3,502,253 are pneumatic compensating devices for wefts for shuttle less looms, in which, from a weft reserve, in each case via a delivery mechanism, a weft is continuously withdrawn and supplied to a pneumatic compensating device. In the latter, the continuously supplied weft is formed into a reserve loop, from which the weft length required for weft insertion is periodically withdrawn for each weft insertion. For this purpose, the weft coming from the compensating device is led via a controlled clamping device to a blowing nozzle which, at the proper moment, blows a section of weft into an open shed.
The length of the blown-in section of weft is determined by the opening time of the clamping device. The weft insertion is interrupted by closing of the clamping device, and the inserted weft section (single pick) is separated from the supplied weft by means of a cutting device. The clamping
REFERENCES:
patent: 2469202 (1949-05-01), Murdock et al.
patent: 3502253 (1970-03-01), van Mullekom
patent: 3665976 (1972-05-01), Freihofer
patent: 3669328 (1972-06-01), Castelli
patent: 4090536 (1978-05-01), Van Mullekom
patent: 4298033 (1981-11-01), Takahashi et al.
patent: 4479518 (1984-10-01), Kiwior
patent: 4646792 (1987-03-01), Villa et al.
Falik Andy
Textilma AG
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