DE1934004A1 - Optical weft thread monitor for a weaving machine - Google Patents

Description

T. 352

Gebrüder S u 1 ζ er Aktiengesellschaft, Winterthur / Switzerland

Optical weft thread monitor for a weaving machine

The invention relates to an optical weft thread monitor for a weaving machine with a transmitter for the weft direction directed beam and a receiver of this beam, which receiver causes the loom to stop in the absence or breakage of the weft thread.

In a known weft thread monitor of this type is the Beam across the line of fire onto a photocell behind it directed. If the weft thread is present, the beam is interrupted by it, so that it does not affect the photocell reached and this does not trigger any switching measures to shut down the loom. Is there no weft thread or is it broken, the beam hits the photocell and this triggers switching measures to shut down the weaving machine.

Experience has shown that the contamination of an optical weft thread monitor is a serious problem. The accruing Dust and air settle on the optical parts - the lenses and the photosensitive element - the transmitter and the receiver. The lubricating oil adhering to the shooter also turns out to be a mist, mixed with dust, settled on the optical parts. Now the intensity of the ray, which experience teaches, becomes one

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should have relatively little value, of course; set when the optical parts are clean. At a A certain degree of pollution of the transmitter and / or the receiver is the radiation intensity coming into effect in the receiver so little that it always reacts as if a weft thread had been inserted, even if it did is not the case. When processing fibrous yarns Often a number of fibers loosen during the weft insertion, which in the Beam of the weft thread monitor can get and then also simulate the presence of a weft thread. The surveillance the weft thread insertion by the weft thread monitor is thus no longer reliable, so the loom goes unnoticed can produce defective tissue.

The invention aims at an optical weft thread monitor to create, undisturbed by the inevitable flight, OeI fog and fiber formation, which reliably monitors the insertion of the weft threads. The weft thread monitor according to the invention is characterized in that switching means are assigned to the receiver, which cause the weaving machine to stop, if no weft thread has been inserted, and that further Trigger switching measures when the on the receiver takes effect coming intensity of the beam has a prescribed value falls below. The advantage is that once the pollution of the optical parts has progressed so far that the weft thread monitor no longer works reliably, the loom is shut down.

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An embodiment of the invention is based on the Drawing explained in more detail. It shows :

Fig. 1 is an overview of a loom of the Product side seen;

2 shows an electrical circuit diagram of a weft thread monitor.

The loom has two cheeks 1, 2 (Fig. 1), between which an invisible warp beam, a fabric beam 3, not shown guide and tensioning devices for warp and fabric, a central beam A connecting the two cheeks and a main drive shaft 5 of the machine are arranged are. Furthermore, a shaft 6 belonging to the shedding mechanism and the reed 7 are visible in FIG. 1.

The firing mechanism 8, which closes the shooter, sits on the cheek 1, and the trapping mechanism is on the right-hand side of the machine 9 arranged, in which the shooter arrives at the end of the shooting process (entry). The weft thread 10 is taken from the supply spool 11, which is usually arranged stationary outside the weft compartment, via a screen 12 and a screen that can be moved up and down Thread tensioner 12 out and carried in the shed.

After the entry, the shooter is pushed back a little in the trapping gear 9 so that he can get one exactly with each shot has the same position. The thread tensioner 13 is moved into the upper position so that the weft thread moves backwards of the shooter is always tense. By not shown

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Thread brakes are set during the return movement of the Schützens made sure that the resulting detour at the thread tensioner 13 primarily by withdrawing the whole entered Weft thread is formed; if necessary, a certain piece of thread is also withdrawn from the bobbin 11.

After the backward movement of the shuttle and the weft thread, the weft thread on the weft side of a (not shown) Scissors cut off. The protruding weft thread ends on both sides of the shed are turned after the reed stop and the shed change placed in the next compartment by a last laying mechanism. The fabric is wound onto the fabric tree 3.

A housing 20 is attached to the safety gear 9 below the line of fire, i.e. the path theoretically covered by the shooter, which includes a transmitter or light source 21 (Fig. 2). A second housing is also attached to the safety gear 22, which is a photosensitive, electrical element or photocell 23 contains. The bundled beam 24 emanating from the light source is directed onto the photocell at right angles to the line of fire. The housing 22 carries a box 25 which contains the electrical part of the weft thread monitor and which is constructed as follows is :

The photocell 23 (FIG. 2) is connected to the input of an amplifier 27 via a resistor 26. The amplifier

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is in turn connected to a Schmitt trigger 28, which The voltage signal of the photocell is converted into a square wave signal. The Schmitt trigger has two outputs 28a and 28b, the two voltages out of phase by 180 ° lead .. Every time that the Schmitt trigger from the photocell, when it is full is illuminated, receives a voltage signal, it flips over and the voltage signals at the outputs change in phase. Of the Output 28a of the Schmitt trigger leads to an input 29a of a NAND gate 29, the output 28b to an input 30a of a second NAND gate 30. A second input 29b of gate 29 is connected to a timing element 31. The outputs 29c and 30c of the gates 29 and 30 lead to a monostable multivibrator 32, the output 32c of which via amplifier elements (not shown) with the (also not shown) main switch of the loom in connection. Furthermore is a switch 33 is also provided, which is controlled by the main shaft 5 of the loom. By means of the switch that normally is open, a second input 30b of the gate can optionally be connected to ground or via a resistor 34 with a positive Voltage to be connected.

The operation of the switches is as follows:

Immediately after the archer arrives in the safety gear 9, the switch 33 is disconnected from the main shaft 5 of the loom opened. As a result, the input 30b of the gate 30 is via the

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Resistor 34 connected to the positive voltage. The ". Phases'- ' The position of the output voltages of the Schmitt trigger is such that the voltage present at input 3Öa is not sufficient to combine to cause the gate to let a signal through with the voltage now prevailing at the input 30b. Wasn't a weft thread has been entered by the shooter, there is no Weft thread in the path of the light beam 24 between the light source 21 and the photocell 23. The photocell is thus fully illuminated and it generates a voltage signal which is amplified in the amplifier 27 and causes the Schmitt trigger 28 to tilt. Through this the signal at the input 30a of the gate 30 changes in phase so that it is now sufficient to, together with that at the input 30b prevailing voltage to cause the gate to output a signal to the monostable multivibrator 32. This will tip over and causes the weaving machine to stop. The same processes take place when the weft thread breaks, which usually takes place shortly behind the shooter The weft thread then forms a small, Loop that circumvents the light beam, which has the same effect as if no weft thread has been inserted.

If a weft thread 10 was inserted by the shooter, as is the case with normal operation of the loom, it is located he is in the way of the light beam 24. This thus does not reach the photocell 23 and this does not generate a voltage signal. The Schmitt trigger therefore does not tip over and the voltage

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at the input 30a of the gate 30 does not change into phase. That The gate thus does not allow a signal to pass, the multivibrator 32 does not tip over and does not initiate any switching measures to shut it down the loom. The machine continues to run and the shooter is ejected after pushing back from the safety gear and to Firing mechanism returned. The weft thread is cut and it follows the reed stop, shed change and slat laying in the next subject. There is therefore definitely no longer a proper weft thread in the area of the light beam between sender and receiver. At this point in time, the optical parts of the weft thread monitor are checked Pollution as follows:

Each time that the switch 33 is opened, the timer 31 is started at the same time by switching it over the resistor 34 is applied to the positive voltage. The running time (e.g. 120 ms) of the timer is longer than the opening time of the Switch 33, which after the monitoring of the entry of the weft thread closes again. The running time, which depends on the working speed of the loom, is so long that the The above-mentioned point in time for the inspection of the optical parts has been reached. At this point in time the timer gives a Voltage on the input 29b of the gate 29. Are the optical parts so dirty that the intensity of the The light coming into effect from the photocell is too small to emit a voltage signal of sufficient amplitude, the pause

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'Schmitt trigger in its position. In this position is the one at the "exit" 28a of the Schmitt trigger and the voltage present at input 29a of the gate is large enough, together with that at input 29b prevailing voltage to cause the gate to pass a signal to the multivibrator 32. This falls over and thereby causes the weaving machine to stop. Instead of soiling the optical parts leave that the loom must be shut down, it is of course possible to use the multivibrator 32 at a lower level Degree of pollution to activate a warning signal, so

- that measures are taken to clean the optical parts can. If the optical parts were sufficiently clean at the above point in time, the photocell emits a voltage signal on Schmitt trigger, which then tips over. The voltage now appearing at the input 29a of the gate 29 is not sufficient to put together to bring the gate to output a signal with the voltage prevailing at the input 29b. The multivibrator tips over therefore not around, and the loom remains in operation.

The weft thread monitor still offers the possibility the monitoring of broken weft threads, which - due to their greater residual length - in the tactile area in the form of a ball to lie down. If a weft thread breaks, the part still clamped in the shooter moves even further in that direction of the fishing gear and accumulates in the area of the light beam in the Shape of a ball. This ball is still in the area of the

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Light beam when checking the cleanliness of the optical Parts takes place. The switching means react to this fact in the same way as if the optical parts are not correct are and turn off the loom.

Instead of using the mechanical switch 33 operated by the main shaft, the required voltage can be applied to the Actuation of the weft thread monitor can be generated by means of the shooter, e.g. by interrupting the light beam at Passing the same draws a pulse for pulse generation or induces a pulse to be generated inductively.

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Claims (4)

Claims Optical weft thread monitor for a weaving machine with a transmitter of a beam directed in the weft direction and a receiver of this beam, which receiver stops the loom in the absence or breakage of the weft thread initiated, characterized in that switching means are assigned to the receiver, which the shutdown cause the loom if no weft thread has been inserted, and trigger the switching measures when the The intensity of the beam that comes into effect for the receiver in the absence of thread falls below a prescribed value * 2. Weft thread monitor according to claim 1, characterized in that the switching means are ready to switch after a weft thread insertion process to check the presence of the weft thread, and then to check the degree of soiling the optical parts or the presence of a ball of thread. 3. Weft thread monitor according to claim 1, characterized in that the switching means is connected downstream of an amplifier element Have Schmitt trigger, whose outputs each with - 11 009817/1261 connected to an input of a first or second NAND gate are, whose outputs in turn lead to a monostable multivibrator that is connected to the Main switch of the loom is in connection, the second input of the first gate by means of a switch optionally with earth or with a voltage source, the second input of the second gate via the same switch a timing element can either be connected to earth or to the mentioned voltage source. 4. Weft thread monitor according to claim 1, characterized in that the shooter generates a pulse for actuating the Switching means. 009817/1261 Blank page