Device for guarding the yarn motion

Abstract

 The invention relates to a device for guarding the yarn motion in a textile machine during unwinding the yarn (P) from the bobbin (1). A sensor (7) of the device is as­signed to a yarn guiding eye (3) for detecting the rotary motion of the yarn which unwinds from the bobbin in a bal­loon. Light emitting diode (71) and a phototransistor (72) can be used as a sensor.

Description

[0001] The invention relates to a device for guarding the yarn motion in a textile machine during unwinding from a bob­bin through a guiding eye around the internal diameter of which the yarn rotates.

[0002] Various types of stop motions are known, which detect the condition of yarns in textile machines. To guard the yarn motion in high-speed, small diameter knitting machines for the production of stockings or socks goods yarn stop motions are used. The Author's Certificate No. 249,827 de­scribes a stop motion system containing a fix piecoelec­tric member connected to the control micro-computer of the machine. Said piecoelectric member responds to the yarn motion and the signal is transmitted and processed in the micro-computer with regard to the program of the yarn feed or withdrawal of the yarn by the machine. The micro-compu­ter gives then a command for eventual stopping of the ma­chine. Said guarding device operates reasonably reliably, but the circuits processing the signal from the piecoelec­tric member must be able to evaluate also the interferen­ces.

[0003] The object of the invention is to eliminate the above-men­tioned disadvantage, what is principally achieved so that the sensor of the device is provided with a guiding eye for detecting a rotary yarn motion.

[0004] The important advantage of the invention is that during withdrawing of the yarn by the knitting feed, the yarn always rotates in the eye, said rotation is safely de­tected by the sensor and therefore the effect of the ma­chine vibration can be entirely eliminated.

[0005] Further advantages and particularities of the invention are realized in the embodiments illustrated in the draw­ings.

Fig. 1 schematically shows the guiding of the yarn from the bobbin through the eye with the use of a pho­toelectric sensor;

Fig. 2 schematically shows a guiding eye for photoelec­tric sensor;

Fig. 3 schematically illustrates another embodiment of the sensor, and

Fig. 4 the electric connection of the stop motion with the photoelectric sensor.

[0006] A single-cylinder, small-diameter, circular knitting ma­chine for the production of socks goods is provided with a stand 1 of bobbins 2. Each bobbin 2 is arranged on a hori­zontal carrier 21 and above the bobbin 2 in the axis of the bobbin there is a guiding eye 3 fixed in a holder 4. Above the guiding eye 3 there is another guiding eye 5 fixed in a holder 6 positioned also in the axis of the bobbin 2. Photoelectric sensor 7 is disposed on the guid­ing eye 3 above the bobbin 2 from outside. Said sensor 7 contains a light emitting diode 71 and by 180° opposite to it there is a stationarily arranged phototransistor 72. Guiding eye 3 does not obstruct the passage of the light from the emitting diode 21.

[0007] The connection of said diode 71 and phototransistor 72 is shown in Fig. 4. The phototransistor 72 is in Darlington's connection with a transistor 8 for current amplification connected to terminals 9 and 10 of the source. The working point of the Darlington's connection is adjusted by a re­sistor 11. A condenser 12 is connected to the inputs of the phototransistor 72 and the transistor 8 to separate direct current component of the signal and further a tran­sistor 13 by its base. The working point of the transistor 13 is adjusted by resistors 14, 15 being connected to its base. A resistor 16 connected in the collector of transi­stor 13 is a working loading resistor. A condenser 17 con­nected to the output of transistor 13 creates together with the resistor 16 a timing circuit. The output of the transistor 13 is connected with the base of a transistor 19 through a resistor 18. In the collector of the trans­istor 19 is connected a resistor 21 and a light emitting diode 22 creating a working load of the transistor 19. The output of the transistor 19 is connected through a diode 20 to an output 23. A switch 24 is parallelly connected between the resistor 18 and the transistor 19. Said out­put 23 is connected to further electronic circuits of the machine.

[0008] The operation of the above described device is as follows. During unwinding of yarn P from bobbin 2, yarn P rotates around the bobbin 2 axis and due to centrifugal force it creates a balloon. Consequently, yarn P continuously fol­lows the internal circumference of guiding eye 3 and pres­ses onto its wall. The rotating yarn P interrupts the light beam emitted by diode 71, so that phototransistor 72 closes and opens in dependence on the semi-axis of the yarn P. Alternating signal of the voltage on the collector of the transistor 8 is supplied through the condenser 12 on the base of transistor 13 which opens and discharges the condenser 17. Within the duration of the time constant influenced mainly by the magnitude of the resistor 16 and the rate of capacity of the condenser 17 the transistor 19 closes, the light-emitting diode 22 extinguishes and the output terminal 23 is disconnected from the potential of negative voltage terminal 9. This ensures voltage level corresponding to logic "1". Voltage condition on this ter­minal 23 is further evaluated in the circuits of the con­trol micro-computer of the machine, which in this case leaves the machine in operation.

[0009] If yarn P is not withdrawn due to breakage, there is no alternate signal, the circuit is in basic condition, i.e. voltage level on terminal 23 corresponds to logic "0" and the control micro-computer stops the machine drive.

[0010] A complete stop motion device is controlled by the switch 24 which when closed connects the base of the transistor 19 with the potential of the terminal 9. The output on the terminal 23 has thus no influence on the micro-computer of the machine.

[0011] To improve yarn detection, it is possible to make the yarn guiding eye from several parts, what is within the scope of the invention. The internal wall of the eye 3 is a glass ring 34 (Fig. 2) and the outer wall is a metal ring 25. In the ring 25 there are two coaxial openings 251 and 252 bored perpendicularly to the surface of the ring 25. The light emitting diode 71 and the phototransistor 72 are assigned from outside. This arrangement ensures that the light beam is not diffused and that it is narrow directio­nal. The phototransistor 72 cannot be influenced by other source of light.

[0012] Further within the scope of the invention the sensor of the device can be created as mechanical. Into internal space of guiding eye 3 (Fig. 3) reaches an arm 261 of a lever 26, the other arm 262 of which reaches into the space between a not shown phototransistor and a light emitting diode. Or instead of lever 26 a piezoelectric member can be installed, the signal from said piezoelec­tric member is processed by the circuits of the micro-­computer.

[0013] The device can be used to guard the yarn motion during unwinding from the bobbin in any textile machine.

Claims

1. Device for guarding the yarn motion in a textile ma­chine during unwinding from a bobbin,
characterized by
a guiding eye (3) in which the yarn (P) rotates around its internal diameter and by a sensor (7) disposed on the guiding eye (3) for detecting the rotary motion of yarn (P).

2. Device according to claim 1, characterized in that a light emitting diode (71) and opposite to it by 180° a phototransistor (72) are assigned to the circumference of the guiding eye (3) from outside.

3. Device according to claim 2, characterized in that the phototransistor (72) is connected in Darlington's con­nection with a transistor (8) to a source of voltage, a condenser (12) is connected to it and a transistor (13) by its base, on the input of which is parallelly con­nected another condenser (17) and the base of another transistor (19), the input of which is connected to the control micro-computer of the machine via a diode (20).

4. Device according to claim 1, characterized in that into the internal space of the guiding eye (3) reaches a mechanical sensor, for example an arm (261) of a lever (26), the other arm (262) of which reaches between a light-emitting diode and a phototransistor.

5. Device according to claims 1 and 2, characterized in that the guiding eye (3) is composed of internal glass ring (34) and outer metal ring (25) in which there are coaxial openings (251, 252) created perpendicularly to its surface.

Drawing