GB2030185A - Apparatus for electrically controlling the wire pull in high-speed stranding machines - Google Patents

Abstract

The invention relates to an apparatus for electrically controlling the wire pull in a high-speed stranding machine, in particular a machine of the tubeless kind, the apparatus controlling the wire pull force in dependence on the speed of rotor rotation and the varying torque at the delivery spools, the apparatus comprising an electric current producing means 1 in the form of a generator driven by the shaft journal 12 for producing electric current for an electromagnetic spool braking system 6 within the rotating system of the high-speed stranding machine, for each delivery spool 4, the generated current which is produced upon rotation of the stranding rotor 13 controlling the energisation system 15 of the electromagnetic spool brake 6, by way of a non-linearity means 2 and a control member 5, with actuation of a regulator 3 which is coupled to a measurement value detection means 16. <IMAGE>

Description

SPECIFICATION Apparatus for electrically controlling the wire pull in high-speed stranding machines The invention relates to an apparatus for electrically controlling the wire pull in a high-speed stranding machine, in particular a machine of the tubeless kind, which is arranged within the rotating system of the machine on the spool carrier frame or cradle of each spool and which operates in dependence on the speed of rotation of the stranding rotor and which uses, as the control member, electromagnetic spool braking systems such as pull armature magnet systems with a friction brake, magnetic powder brakes or hysteresis brakes.

Modern high-speed stranding machines, in parti cularthose of the tubeless kind, are operated at speeds of rotation of from 3000 to 8000 mien~1, depending on their size (spool diameter). In tubeless high-speed stranding machines which operate without a guide for the wire loop portions, there are relatively large distances between the wire guide means, in the region of the wire supply spools, that is to say, the wire passing to the stranding point forms free loops around the following supply spools, the radii of the loops depending on the one hand on the size of the delivery spool and on the other hand on the centrifugal force acting thereon and the wire pull force which opposes the centrifugal force. This means that the wire pull force becomes the determining variable factor with regard to formation of the required loops.The wire pull force on the other hand in turn depends on the magnitude of the braking force which is applied to the wire which is running off the spools. The supply spools are braked in the usual manner, whereby the order of magnitude of the wire draw-off force is determined. In accordance with DAS No.2164131 International Classification D 07 B, 3/04, a spool brake on a tubeless stranding machine is known, which comprises an assembly member which is secured to the spool frame and which extends in front of the spool and which is so bent that its end lies in the middle of the width of the spool. Mounted pivotally on the assem bly member is a single-armed control lever whose free end is divided into two arms.A wire guide sleeve is arranged on one end of the control lever, which is towards the delivery spool, while a guide roller is arranged on the other arm which is to the rear in the wire draw-off direction. The control lever is urged in the draw-off direction by a torsion spring and is pressed resilientlyagainstthe assembly member, in the operating condition of the machine.

Afurtherwire guide roller is mounted on the assembly member, at a somewhat lower position than the guide roller on the control lever. A brake disc over which a brake band is laid is non-rotatably connected to the delivery spool. One end of the brake band is secured to the control lever and the other end is secured to the assembly member. This manner of fixing the ends of the brake band permits coarse and fine adjustment of the braking force. This wire tension control apparatus is intended to ensure that there is a uniform braking force which corresponds to the adjusted value. Although this spool brake or wire tension control apparatus takes account of the wire tension directly after the supply spool, it has little influence on the other parameters which give rise to trouble, in the course of the wire being guided through the entire length of the rotor.

A particular feature of the high-output high-speed stranding machines of tubeless kind, in particular those which have a larger number of spools, is that a friction-free stranding material guide action is not possible in the start-up or braking phase, because the material to be stranded is deflected in direction frequency and severely, as a result of the larger number of delivery spools. As however relatively high braking forces are employed in the operating condition, in order to maintain the required loops which are not intended to exceed a given loop length, it is not possible to use the above-described wire tension control apparatus.This apparatus would either allow the loop length of the stranding material to be increased beyond the permissible limit, or the tensile stress in the stranding material would be excessively high in the start-up and braking phase, so that rupture of the stranding material would occur. For this reason, it has aiready been proposed that a braking system be used, comprising a combination of the usual spool brake which is dependent on the wire pull, and a centrifugal brake which is dependent on the speed of the stranding material. In this case, after the stranding material has left the delivery spool, it is guided over a roller which is braked by centrifugal force and is there braked with a braking force which rises or falls proportionately with the centrifugal force.This braking system which is highly variable and highly adaptable in its braking action and thus in regard to the wire pull force, suffers however from a disadvantage, namely that the braking force occurs in the form of a frictional force on the stranding material and could therefore lead to damage thereof. In addition, the braking member suffers from wear due to the stranding material sliding thereover, and a worn condition or surface fouling result in fluctuations in tbe braking action.

According to the present invention there is provided apparatus for electrically controlling the wire pull in a high-speed stranding machine, comprising an electric generator arranged in a spool carrier mounting for the supply of electrical current to an electromagnetic spool braking system, the rotatable member of the generator being connected to the shaft journal of the stranding rotor, the current produced by the generator controlling the energisation of the electromagnetic braking system by a non-linearity means and a control member.

The invention provides an apparatus for electrical ly controlling the wire pull in high-speed stranding machines, which controls the wire pull force when starting up and running down the stranding machine, by way of the rotor speed, and which regulates the wire pull force during a stationary condition of operation, by way of a predetermined desired value.

The invention further provides that the generator comprises an iron circuit and coil system, which iron circuit is arranged on the bearing housing, and a rotatable permanent magnet ring of alternating polarity, carried on a shaft member connected to the shaft journal of the respective rotor section, the coil system being electrically connected to the nonlinearity means and, by way of the control member, to the energisation system of the spool brake.

A further feature of the invention provides that, for supplying power to the whole of the electrical means, in addition to the generator, there are also provided an energy storage means which is independent of the speed of rotation, and, for the regulator, a means for monitoring the undervoltage and a measurement value detecting means.

The invention further provides that the desired value of the wire pull force is controlled in dependence on the speed of the rotor rotation.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 shows a view in longitudinal section of a part of the rotor section of a tubeless high-speed stranding machine, with the spool carrier mounting and the generator, and Figure 2 shows a diagrammatic illustration of the apparatus for controlling the wire pull force.

The apparatus shown in Figures 1 and 2 essentially comprises an electrical generator 1 acting as a source of electric current, a non-linearity means 2, a control member 5 with regulator 3 and an electromagnetically actuated spool brake 6. The generator 1 is shown in greater detail in Figure 1 and is secured to a bearing housing 8 of the spool carrier or cradle 7 and comprises an iron (magnetic) circuit 9 with a coil system 10 and a permanent magnet ring 11 which is of fluctuating polarity and which in turn is arranged on a shaft member 14 which is connected to the shaft journal 12 of the stranding rotor 13. The non-linearity means 2 may be a diode resistance network or a non-linear resistance which is supplied by the generator 1. The control member 5 is either a transistor, thyristor with a triggering means or a variable resistor or a switch means.

The apparatus further includes the energisation system 15 for the electromagnetic spool brake 6 and a stabilised current-supply means 17 for the regulator 3 and a measurement value detecting means 16.

The regulator 3 essentially comprises an electrical, electromagnetic or mechanical comparison means for comparing the actual and desired values of the wire pull force, and a means for controlling the desired value of the wire pull force, in dependence on the speed of rotor rotation. The current supply means 17 generally comprises a stabiliser, an energy storage means which may be a capacitor or an accumulator, and a means for monitoring for undervoltage. The measurement value detecting means 16 is either a force or a travel measuring system, although other constructions for detecting the wire pull force can also be used.

The mode of operation of the apparatus according to the invention is as follows: When the stranding rotor 13 is not rotating, there is only a braking force which is tending towards zero, resulting from the bearing friction, acting at the spool brake 6. When the stranding rotor 13 begins to rotate, a voltage is produced in the generator 1, the amplitude of which voltage rises with increasing speed of rotor rotation. By way of the non-linearity means 2 and the control member 5, this voltage supplies a current into the energisation winding of the energisation system 15 for the spool brake 6, which in turn applies a braking action to the delivery spool 4.The energisation current, which is produced by the generator 1, for the electromagnetic spool brake 6, is not controlled by the control member 5, up to a given speed of rotor rotation, as the undervoltage monitoring means in the current supply means 17 has fully opened the control member 5, by way of the regulator 3. When a given speed of rotor rotation is reached, the regulator3 is fully functional and, by way of the comparison between the desired value and the actual value of the wire pull force, influences the control member 5 in such a way that the wire pull force rises in dependence on the speed of rotor rotation and reaches its required limit value when the operating speed of rotation is reached.

The process takes place in the reverse manner when the stranding machine is shut down.

If the technological parameters change, that is to say, the wire to be stranded is of a different cross-section, a change in the electrical rate values is effected by means of a manual input, thereby resulting in a change in the predetermined desired value. As the current producing means (generator 1) and the control member 5 are disposed within the rotating system, there is no need for electrical power to be transmitted by means of slip rings. In addition, there is no frictional loss on the wire which is drawn off, and at the braking means. The wire pull force is constant, irrespective of the condition of wear and of fouling of the frictional elements. Changing over the values in respect of the wire pull force, which is necessary when changing the stranding program, is simple and gives rise to no problems.

Claims (5)

1. Apparatus for electrically controlling the wire pull in a high-speed stranding machine, comprising an electric generator arranged in a spool carrier mounting for the supply of electrical current to an electromagnetic spool braking system, the rotatable member of the generator being connected to the shaft journal of the stranding rotor, the current produced by the generator controlling the energisation of the electromagnetic braking system by a non-linearity means and a control member.

2. Apparatus as claimed in claim 1, in which the generator comprises an iron circuit and coil system, which are arranged on the bearing housing, and a rotatable permanent magnet ring of alternating polarity, carried on a shaft member connected to the shaft journal of the respective rotor section of the stranding rotor, the coil system being electrically connected to the non-linearity means and, by way of control member, to the energisation system of the spool brake.

3. Apparatus as claimed in any preceding claim, in which for supplying power to the above-indicated electrical means, in addition to the generator, there are also provided an energy storage means which is independent of the speed of rotation, and, for the regulator, a means for monitoring for undervoltage and a measurement value detecting means.

4. Apparatus as claimed in any preceding claim, in which the desired value of the wire pull force is controlled in dependence on the speed of rotor rotation.

5. Apparatus for electrically controlling the wire pull in a high-speed stranding machine, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.