GB2090969A

GB2090969A - Circuit for Monitoring Photoelectric Control Systems

Info

Publication number: GB2090969A
Application number: GB8132764A
Authority: GB
Original assignee: Schwermaschinenbau Kombinat Ernst Thalmann VEB
Current assignee: Schwermaschinenbau Kombinat Ernst Thalmann VEB
Priority date: 1981-01-09
Filing date: 1981-10-30
Publication date: 1982-07-21
Also published as: ATA452681A; IT1139697B; HU183645B; IT8125023A0; AT384046B; DD156278A1; GB2090969B; DE3140809A1

Abstract

A circuit for monitoring photoelectric control systems in high speed stranding machines which systems constantly monitor the position of the coil or spool carrier frames or cradles, in which the outputs of monitoring light barriers 1 are connected to the inputs of an AND-gate 2 and an OR-gate 3, the output of which is connected via NOT- circuit 4 to OR-gate 6, which also receives the output of AND-gate 2, and whose output is connected by AND-gate 7, timing circuit 8, and AND-gate 9 and OR-gate 10 forming a holding loop, to relay 11 for disconnecting the drive and actuating brakes, the second input of AND gate 7 being connected to the output of equivalent gate 5, whose inputs are connected to OR-gate 3 and to a signal transmitter 12 contactlessly sensing the stranding rotor 13 on its yoke. Transmitter 12 may be replaced by a generator 15 and the circuit slightly modified. <IMAGE>

Description

SPECIFICATION Circuit for Monitoring Photoelectric Control Systems The invention relates to a circuit for monitoring photoelectric control systems, particularly on high speed stranding machines, the control system constantly monitoring the position of the frames or cradles which carry the coils or spools and the light barriers themselves and signalling any deviations.

The coil frames spools or coils in high speed machines are carried in frames or cradles freely mounted on the axis of rotation of the stranding machine so that they can rotate easily. Since their centre of gravity is low, they tend to remain in their normal position and move out of it only when the bearing friction becomes greater than the retaining force. When this happens it is necessary to bring the machine to a standstill as quickly as possible. The position of the or each frame or cradle therefore has to be constantly monitored. The first monitoring systems or disconnecting devices were switching contacts arranged on the frame or cradle; when the frame of cradle moved, i.e. rocked, they broke the drive circuit and caused the brakes of the unit to be operated.These systems, which were located inside and provided with contacts, had a serious technical disadvantage, namely that the electric current is conducted through slip rings. To avoid transmitting signals by means of slip rings, a change was made to monitoring the frames or cradles with light barrier systems. DD-PS no.

105 478 described such a system, which for every carrier frame or cradle comprises two light sources of different types located outside the stranding rotor, the beams from these sources being directed through shutters at an angle to one another, passing through the window apertures of the stranding rotor and being directed straight onto photo receivers or reflected onto them. The pulses which appear when the stranding rotor is rotated are fed to an electronic counter, which transmits a signal to disconnect the machine when a pulse sequence is missing.

Although DD-PS no. 55 246 describes a light barrier system with only one light barrier per coil frame, this system operates without self monitoring. Nor does the system illustrated operate reliably in all cases. The light barrier system in DD-PS 105 478 is indeed really reliable in operation, yet it is very expensive. Thus two light barriers are required for each coil frame, and in addition expensive counters and components are required for self monitoring.

According to the present invention there is provided a circuit for monitoring photoelectric control systems, particularly in high speed stranding machines, wherein the control systems constantly monitor the position of the coil or spool carrier frames or cradles and signal any variations in the position thereof, in which the outputs of the light barriers monitoring the carrier frames or cradles are electrically connected to the inputs of an AND-gate and an OR-gate, and the output of the OR-gate is connected via a NOTcircuit and a further OR-gate to the output of said AND-gate, and that the output of said further ORgate is connected by a further AND-gate, a timing circuit and via another AND-gate and another ORgate, forming a holding loop, to a relay for disconnecting the drive system and actuating brakes of the machine, while the second input of said further AND-gate is connected to the output of an equivalent gate, one input of which is linked with the first mentioned OR-gate and the second input of which is linked with a signal transmitter which senses the stranding rotor or its yoke without making contact.

In stranding machines without tubes or yokes the invention further provides for the signal transmitter which senses generator, which is electrically connected, firstly with the input of the equivalent gate and, in parallel via a delay element, with the second AND-gate, and secondly in parallel with the light barriers.

Further according to the invention, the charging time constant of the delay element is substantially greater than the discharging time constant.

Another feature of the invention is that the transmission shaft is provided as the signal generator for the transmitter which senses without making contact, instead of the stranding rotor.

Two embodiments of the invention will now be described, by way of examples, with reference to the accompanying drawings, in which: Figure 1 is a circuit arrangement for a highspeed stranding machine with a tubular rotor or with a yoke, and Figure 2 is a circuit arrangement for tubeless high-speed stranding machines.

In the circuit arrangement shown in Figure 1, all the outputs of the required light barriers 1, which will correspond to the number of coil frames or cradles, are taken to an AND-gate 2 and in parallel therewith to an OR-gate 3. The ANDgate 2 is connected at its output side to the input of an OR-gate 6, which is in turn connected to an AND-gate 7. The connection extends via a timing circuit 8, AND-gate 9 and OR-gate 10 to a relay 11. A holding loop is formed between the ANDgate 9 and the OR-gate 10. The OR-gate 10 is further linked with a receipting element 14. The OR-gate 3 is connected at its output side to an equivalent gate 5 and a NOT-circuit 4. The circuit 4 is connected at its output side to the input of the OR-gate 6.The NOT-circuit 5 is further connected at its output side with the input of the AND-gate 7, and at the input side with a signal transmitter 12. When the coil frames or cradles (not shown) are in their normal position, the beams of the light barriers 1 can pass through the window of the stranding rotor 13, either directly to the receiver or indirectly via a reflector belonging to the light barrier system. High signals appear at the output of all the light barriers 1 arranged on the stranding machine, so that a high signal also appears at the output of the AND-gate 2 and passes via the OR-gate 6 to the AND-gate 7. For a high signal te appear at the output of the AND-gate 7, the output of the equivalent gate 5 must transmit a high signal. This happens whenever the inputs of the gate 5 have the same transmission level.Since a high signal appears through the OR-gate 3, the signal at the contactfree transmitter 12 must also have a high level.

Either the negated or the non-negated output will be used here, according to the nature of the transmitter 12. The contact-free transmitter 12 must sense the apertures in the stranding tube.

Owing to the wire guides on the stranding tube 13, the transmitter 12 is arranged at the end and senses the apertures in the stranding tube through equivalent segments. If the light barrier 1 reflects (fails or drops out) in such a way that the output transmits a low signal although beams are striking the receiver, the relay 11 will receive a switching pulse via the AND-gate 2 and the downstream gates 6, 7, 8, 9, 10. The circuit for the stranding machine drive will be interrupted and the brakes set in action.

If the beams of the light barriers 1 are interrupted by the stranding tube 13, i.e. by its window flanges and/or the yokes of the wire guide, a low signal will appear at the output of the gates 2, 3. Since the transmitter 12 also gives a low signal at the same moment, there will be a high transmission level at the output of the equivalent gate 5. A high signal will pass from the NOT-circuit 4 via the OR-gate 6 to the second input of the AND-gate 7. The high signal coming from the equivalent gate 5 is applied to the first input. Hence the relay 11 does not receive any switching pulse.

The circuit arrangement shown in Figure 2 differs from that in Figure 1, substantially only in that the transmitter 12 is replaced by a generator 15 with a delay element 16 downstream of it. The generator 15 takes over the function of the transmitter 12 and also switches the light barriers 1 on and off. It is monitored by the delay element 1 where the charging time constant is substantially greater than the discharging time constant. The output of the delay element 16 is taken to the negated input of the AND-gate 7.

Trouble with the light barriers 1, such that a high level is maintained at the output when the beam is interrupted, does not cause the stranding machine to be switched off in the case of simple light barrier systems, that is to say, any inadmissible deflection of the coil frame is not recorded.

The present circuit arrangement records such trouble via the gates 3, 5. The stranding machine drive is switched off and the brakes operated by means of the gates 7, 8, 9, 10 and relay 1 The timing circuit 8 (gate) presses undesirable switching peaks, and gate 9 and gate 10 form a holding loop. If a high signal is briefly transmitted to the input of the receipting member 14, e.g. by means of an "error receipting" key, the high signal will pass through gate 10 to the relay 1 This will release the brake and unlock the drive for the stranding machine. If, however, a low signal appears at the input of the gate 9 coming from the timing circuit 8, then the relay will drop out via the gates 9, 10 and will remain disconnected, even when the high signal returns, until the error is receipted at the receipting element 14.

Claims

1. A circuit for monitoring photoelectric control systems, particularly in high speed stranding machines, wherein the control systems constantly monitor the position of the coil or spool carrier frames or cradles and signal any variations in the position thereof, in which the outputs of the light barriers monitoring the carrier frames or cradles are electrically connected to the inputs of an AND-gate and an OR-gate, and the output of the OR-gate is connected via a NOT-circuit and a further OR-gate to the output of said AND-gate, and that the output of said further OR-gate is connected by a further AND-gate, a timing circuit and via another AND-gate and another OR-gate, forming a holding loop, to a relay for disconnecting the drive system and actuating brakes of the machine, while the second input of said further AND-gate is connected to the output of an equivalent gate, one input of which is linked with the first mentioned OR-gate and the second input of which is linked with a signal transmitter which senses the stranding rotor or its yoke without making contact.

2. The circuit claimed in claim 1, in which in stranding machines without tubes or yokes, the signal transmitter which senses without making contact is replaced by a generator, which is connected firstly with the input of the equivalent gate and, in parallel via a delay element, with said further AND-gate, and secondly in parallel with the light barrier

3. The circuit claimed in claim 2, in which the charging time constant of the delay element is substantially greater than the discharging time constant.

4. The circuit claimed in claim 1, in which the transmission shaft is provided as signal generator for the transmitter, instead of the stranding rotor.

5. A circuit for monitoring photoelectric control systems, particularly in high speed stranding machines, wherein the control systems constantly monitor the position of the coil or spool carrier frames or cradles and signal any variations in the position thereof, substantially as hereinbefore described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawings.