DE29900477U1 - Weft monitoring device, in particular for ribbon looms - Google Patents

Description

TELEPHONE: 0 711/78.^733J &Tgr;&sfgr;&xgr;&KHgr;&Egr;&Lgr;&&KHgr; : .0*7 3.1*/7 8 0 0 9 9 5 / 9 6

KÖHLER SCHMID + P. RUPPMANNSTR. 27 D-70565 STUTTGART

KÖHLER SCHMID + PARTNER

PATENT ATTORNEYS

23 095 S/go

Ilitex AG
Seestrasse 1
CH 6330 Cham

Weft thread monitoring device especially for ribbon weaving machines

The invention relates to a weft thread monitoring device, in particular for ribbon weaving machines, in which the weft thread is guided over at least one pivoting spring arm, which interacts with a switch-off device for faulty weft insertions. The weft is fed continuously by means of a transport device. If the processing is error-free, approximately twice the width of the belt of thread is supplied and processed per weft insertion. The intermittent processing on the one hand and the constant delivery on the other hand are balanced out by one or more spring arms, which take over the excess amount of thread by pivoting out.

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The springs also serve to monitor errors. With every crocheting error, thread consumption decreases. The excess is compensated by the springs so that they can swing out a corresponding amount. If the excess is so large that the springs touch an end stop, the machine is switched off. If belts of different widths are processed on the same machine, then with narrow belts many errors are necessary until there is an excess of thread that allows the springs to swing out to the end stop. With wide belts, on the other hand, the machine switches off relatively quickly.

Every weft insertion that is not properly crocheted is a fault that is found and cut out during the goods inspection. Due to wear and tear on the weaving machine or due to yarn irregularities, a well-set-up machine may begin to produce isolated crocheting faults at longer intervals. This means that a product is created that has such faults at longer intervals, for example every ten meters. Since a saleable roll of fifty meters can only have one cut, a belt that has such crocheting faults at longer intervals is waste. Such faults at longer intervals are difficult to detect with the known monitoring equipment. As a result, a machine can run in this way for one or more days and produce faults. In extreme cases, this can result in several thousand

send meters of defective goods, which represent a significant financial value. The known devices all have the disadvantage of only being able to measure thread consumption very roughly.

In order to switch off the machine in a simple manner even if there are just a few errors, regardless of the belt width, according to the invention, several light sources or a light strip are provided on one side of the spring arm in the swivel area and on the other side several photocells are provided one behind the other in the swivel direction, whereby the photocells are connected to a measuring device that measures the path of the spring arm and activates the switch-off device. With a device of this type, the path of the spring is measured using the number of photocells passed through. Even with minor crocheting errors, the spring arm passes over another segment of the light sources or photocells. In this way, it is possible to use deviations that exceed a permissible difference to shut down the machine after just a few crocheting errors. This achieves an exact display of the thread consumption.

Preferably, light-emitting diodes are provided as light sources. The spring arm can pivot in the slot of a guide housing, whereby the light sources or the light strip and the photocells are attached to the opposite slot walls of the housing.

The guide housing is designed to be angled or curved.

In the known devices, two opposing spring arms are usually used, over which the weft thread is guided. In this case, the guide housings are arranged with their free ends at a distance from one another and the weft thread is guided between them. Particular advantages arise when a measuring device is used which has a memory for the measured path of several weft insertions. The measuring device can then form an average value, which is compared with the next weft insertion. Any deviation from the average value is an error. The size of the deviation, which leads to a shutdown, and thus the sensitivity, can be adjusted. Changes in the width and thread tension also influence the behavior of the springs. The device can therefore also be used to determine limit values based on other errors.

The drawing shows an embodiment of the invention. It shows:

Figure 1 shows the front view of a weft thread monitoring device with a partially sectioned guide housing

- 5 Figure 2 the section II-II according to Figure 1

The weft thread monitoring device consists of two similar guide housings 1, in each of whose slots 2 a spring arm is arranged so as to be pivotable about an axis 4. In the pivoting area 5, light-emitting diodes 7 are arranged one behind the other on one slot wall 6, while photocells 9 are provided on the opposite slot wall 8, corresponding to the light-emitting diodes 7. The guide housings 1 are curved and a weft thread 11 is guided between their free ends 10, which has previously been guided through eyelets 12 of the spring arms 3.

The feed of the weft thread 11 (not shown) is continuous, while the processing is intermittent. The excess amount of thread is compensated for by swinging out the spring arms 3. The spring arms 3 swing past the LEDs 7 and the photocells 9, whereby the photocells are connected to a measuring device (not shown). In this way, the distance covered by the spring arms 3 can be measured. If this distance is too great, more or different photocells are activated and the machine is then switched off via the measuring device.

Claims (6)

·· ··23095S/go- 6 - Claims 1. Weft thread monitoring device, in particular for ribbon weaving machines, in which the weft thread is guided over at least one pivotable spring arm which cooperates with a switch-off device for faulty weft insertions, thereby
characterized in that in the pivoting area (5) of the spring arm (3) on one side thereof several light sources (7) or a light band and on the other side several in the pivoting direction (5) photocells (9) arranged one behind the other are provided, wherein the photocells (9) are provided with a path of the spring arm (3)
measuring device which activates the shutdown device. 2. Device according to claim 1, characterized in that light-emitting diodes (7) are provided as light sources. 3. Device according to one or both of the preceding claims, characterized in that the spring arm (3) in the
Slot (2) of a guide housing (1), whereby the
Light sources (7) or the light strip and the photocells (9) on
the opposite slotted walls (6, 8) of the housing (1). -&Igr;&Agr;. Device according to claim 3, characterized in that
the guide housing (1) is angled or curved
is. 5. Device according to one or both of the preceding claims 3 and 4, characterized in that two opposite
Spring arms are provided over which the weft thread
(11) and that two guide housings (1) with
their free ends (10) are arranged at a distance from each other and the weft thread (11) is passed between them. 6. Device according to one or more of the preceding
Claims, characterized in that the measuring device has a memory for the measured path of several weft entries and has a further device for comparing these weft entries with the next one.