GB2179377A - Stop motions in tubular stranding machines - Google Patents

Abstract

The machine has a stranding tube (22, Fig. 2) rotating about a rockable bobbin cradle (23) to which a shutter (25) is attached. Two elements (24) rotate with the tube to produce signals in a stationary generator (11). Holes (20) in walls rotating with the tube (22) allow passage of a light beam as they rotate to produce a signal in a receiver (1, Fig. 1). A counter (8) counts a signal from the receiver (1) and is reset by a following signal from the generator (11). A counter (9) counts a signal from the generator (11) and is reset by following signal from the receiver (1). If the receiver or generator fail, or the light beam is interrupted by the shutter (25) rocking with undesired cradle rocking, then a counter memory fills and triggers a stop command in a flip-flop (17) via a NOR element (16). A clock generator (3) is used so that the machine is stopped if no signal is transmitted by the receiver (1) within a preset time. The preset time is lengthened during machine acceleration. <IMAGE>

Description

SPECIFICATION Circuit arrangement for monitoring the reciprocating movement of barrel frames in a stranding machine This invention is for use in the cable manufacturing industry, for monitoring the stranding process, particularly for monitoring barrel frames or cradles in stranding machines.

Barrel frame or cradle monitoring means in quick action stranding machines are known in many different forms. Most of the known means work on the principle of each frame or cradle being monitored separately. In the optical monitoring means disclosed in DD-PS 226893 and DE-PS 55 246 a light barrier is provided for each barrel frame or cradle, the system in PS 55 246 operating without any self monitoring. The arrangement in DE-OS 2408 546 contains a barrel frame monitoring means with two different light sources per frame and two corresponding receivers. The beams which pass through the window apertures of the stranding tube and are directed by shutters form an angle to one another and are sent on to the photosensitive cell either directly or reflected.The disadvantage of these monitoring means is that each barrel frame needs at least one measurement transmitter and one measurement receiver; these are expensive to provide and take up a consierable amount of space. In addition the transmitter, receiver and reflector very quickly become dirty through being located on or in the stranding tube and this makes the monitoring means unreasonably prone to trouble.

All these deficiencies are avoided in the monitoring means disclosed in DE- OS 3034373. The basic construction described therein is with the light source and receiver outside the end walls of the stranding tube so that the light beam to the light barrier runs inside the tube. A shutter is arranged on each barrel frame or cradle, and when the frame or cradle reciprocates inadmissably beyond a certain angle the shutter interrupts the light beam and thus switches off the drive of the stranding machine. However, this monitoring means has the disadvantage that it cannot be set in operation until a speed of 200 to 300 min-' is reached. This is because while the stranding tube is starting up the interruptions to the light beam caused by the end surfaces last so long that a disconnecting pulse would be produced immediately.It is therefore necessary to provide a disconnection stop for the starting process or to lengthen the pulse duration.

Whereas the pulse duration cannot be lengthened because of the collision risk that this would involve (in the event of collision disconnection takes place too late or not at all), the disconnection stop leads to failures through human error, e.g. if the disconnection stop is not removed and the monitoring means consequently does not come into operation when the stranding machine has started up. If the barrel frame or cradle bearings become blocked, with the path of the rays going exactly from the transmitter to the receiver, the monitoring means is quite useless. It still records a pulse at each revolution, thereby signalling that the machine is operating satisfactorily, but the co-rotating barrel frame or cradle may cause collisions with considerable damage within a very short time.

The invention aims to provide a substantially improved means for monitoring barrel frames or cradles. It must be free from the above disadvantages and must guarantee that damage to bearings and rotors from co-rotating barrel frames of stranding machines are avoided, so that technical safety is considerably improved and stoppages for repair are reduced so that productivity can be increased.

The problem on which the invention is based is to provide a monitoring means using a circuit arrangement for monitoring pivotably mounted barrel frames or cradles, where the stop command to immobilise the stranding machine is issued within half a revolution of the stranding tube regardless of the speed of the tube, i.e. the frame or cradle monitoring means becomes operational as soon as the stranding machine starts up, and in addition the machine is switched off automatically in fractions of a second if the barrel frame or cradle bearings become blocked.

According to the present invention there is provided a circuit arrangement for monitoring the reciprocating movement of a barrel frame or cradle in a stranding machine, said circuit being a self monitoring circuit and using a light signal generated by the machine, a pulse generator and a signal pickup system made up of logic blocks, comprising a receiver coupled to the signal pickup system for receiving the light pulses which emanate from a light source and are guided through a shutter, said pulses being fed via a pulse shaper to counters that are combined by the circuitry with the pulses which are generated in the generator by the rotating stranding tube and monitored by an equivalence element, and further combined with pulses generated by a clock generator and sent to a counter, a divisor and a further counter, the outputs of two of the counters and of the equivalence element being connected by the circuitry to a flip-flop directly by a NOR element, the outputs of two other counters being connected to said flip-flop via two other NOR elements and said NOR elements and said NOR element and the output of a counter are connected to said flip-flop via another NOR element, a flip flop and said two other NOR elements.

Another feature of the invention is that the shutter of each barrel frame is a recessed circular disc, corresponding in size to the maxi mum allowable reciprocating range for a barrel frame. Since the two holes in the end wall and the two actuating elements of the pulse generator are offset by 90 , a pulse is emitted alternately by the receiver receiving the light pulses and by the pulse generator. In this way the associated counters receive a count and a reset pulse within half a revolution and check up on one another's proper functioning and on the reciprocating amplitude of the barrel frame. So if the corresponding reset pulse is not received within half a revolution, the machine will be switched off without delay.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 is a block circuit diagram of the circuit arrangement, and Figure 2 shows the arrangement of the shutter on a barrel frame with the stranding tube in cross section, the arrangement of the pulse generator and elements for operating it, and the holes in the end wall of the machine.

The monitoring means shown in Fig. 1 comprise a receiver 1 for receiving light pulses which are produced on rotation of the stranding tube, through two holes 20 for the path of the light rays, the holes 20 being provided in the end wall of the machine and the intermediate walls, offset relative to each other by 1800. The pulses are shaped into right-handed ones in a pulse shaper 2 and transmitted to counters 4, 5, 7, 8 and 9. The pulses from a pulse generator 11, which is influenced by the rotating stranding tube and the actuating elements 24 offset by 1800 on the tube, are taken to the count and reset inputs of the counters 8 and 9 and to the equivalence element 10. The outputs of the counters 8 and 9 and element 10 are linked directly with a NOR element 16.The counters 5, 7, 8 and 9 are connected to flip-flops 14 and 17 and to a start-stop switch 19. The output of the counter 7 is connected by a NOR element 12 to the NOR element 16. The counter 7 is also connected by circuitry to the output of the clock generator 3 by a divisor 6. The generator 3 is connected to the NOR element 16 by the counter 4 and NOR element 15. The output of the counter 5 is taken via a NOR element 13 and flip flop 14 to a NOR element 15, while the NOR element 16 is directly connected to the flip-flop 17.

Fig. 2 shows the basic construction of the reel frame monitoring means; the pulse generator 11 is arranged stationary while the two actuating elements 24, which are fixed to the stranding tube 22 in positions offset by 1800, join in the rotating movement when the stranding machine is operated. The holes 20 for the light rays, formed in the end wall of the machine and the intermediate walls, can also be seen, offset by 90" from the actuating elements 24. These two holes 20 also join in the rotating movement of the machine, thus producing the light pulses. The figure also shows the frame or cradle 23, which is mounted so that it reciprocates, and the shutter 25 rigidly connected to the barrel frame 23.

The operation of this embodiment will now be explained.

By means of the structural arrangement of the pulse generator 11, the actuating elements 24, the holes 20 for the light rays, and the circuitry described, the counters 8 and 9 count a pulse and are then reset. The counter 8 counts the pulse from the receiver 1 within half a revolution of the rotor and is reset by the pulse from the pulse generator 11. The counter 9 counts the pulse from the generator 11 and is reset by the pulse from the receiver 1. If the receiver 1 or pulse generator 11 fails and if the light pulses fail because the shutter 25 swings into the path of the light source (Fig. 2) then the memory of the counter where the reset pulse failed fills up and thus triggers the stop command to immobilise the machine, in a flip-flop 17 connected downstream of the counter 8 or 9 via the NOR element 16.

In addition to this method of monitoring the reciprocating movement of the barrel frame or cradle, there is a second possible method in the circuits described. This is monitoring by timing. If no pulse is transmitted by the receiver 1 within a preset time the machine is switched off. The two monitoring systems work in parallel, the system which produces the fastest disconnection coming into effect.

While the machine is accelerating it is switched over electronically from a longer monitoring time for low speeds to a shorter time for higher ones. This is done by the counter 5 connected downstream to the NOR element 13, the flip-flop 14 and the NOR ele ment 15. The clock frequency produced by the generator 3 is fed to the counter 4 and, via a divisor 6, to the counter 7 connected downstream to the NOR element 12. These two counters count the generator pulses between the individual light pulses by which they are reset and restarted. If the counters exceed a given number of pulses, due to omission of light pulses, this causes the stranding machine to be disconnected. The pulse generators 11 are further monitored for voltage failure by an equivalance element 10 and the power supply unit 18; if the voltage fails there is again a stop command to immobilise the machine.

This circuit arrangement ensures that the stop command to immobilise the machine is given within half a revolution of the stranding tube regardless of the speed of the tub'è, that the -barrel frame monitoring system is in proper service condition when the stranding machine starts, and that the machine will be switched off in any case if the barrel frame bearings cause a blockage.

Claims (4)

1. A circuit arrangement for monitoring the reciprocating movement of a barrel frame or cradle in a stranding machine, said circuit being a self monitoring circuit and using a light signal generated by the machine, a pulse generator and a signal pickup system made up of logic blocks, comprising a receiver coupled to the signal pickup system for receiving the light pulses which emanate from a light source and are guided through a shutter, said pulses being fed via a pulse shaper to counters that are combined by the circuitry with the pulses which are generated in the generator by the rotating stranding tube and monitored by an equivalence element, and further combined with pulses generated by a clock generator and sent to a counter, a divisor and a further counter, the outputs of two of the counters and of the equivalence element being connected by the circuitry to a flip-flop directly by a NOR element, the outputs of two other counters being connected to said flip-flop via two other NOR elements and said NOR element and the output of a counter are connected to said flip-flop via another NOR element, a flip flop and said two other NOR elements.

2. The circuit arrangement as claimed in Claim 1, in which the shutter of the barrel frame or cradle has a round, recessed shape, its size depending on the maximum allowable reciprocating range of the frame.

3. A circuit arrangement for monitoring the reciprocating movement of a barrel frame or cradel in a stranding machine, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

4. A stranding machine provided with a circuit arrangement as claimed in any preceding claim.