GB1586531A - Tubeless standing machine - Google Patents

Description

(54) TUBELESS STRANDING MACHINE (71) We, VEB SCHWERMASCHIN ENBAU-KOMBINAT ERNST ThAL- MANN MAGDEBURG, a body corporate organised and existing under the laws of the German Democratic Republic, of 20 Marienstrasse, 3011 Magdeburg 11, German Democratic Republic, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a tubeless stranding machine of the type in which the strands pass in a free flight curve about the zone of the spools, bobbins or reels and particularly, but not exclusively, to such a machine for producing stranded conductors and cables.

In such machines the spools, bobbins or reels are arranged between several rotor sections and the supports for the spools, bobbins or reels are mounted on end journals of these sections, the wires or conductors, running off the reels, being guided along the machine in a sinusoidal path about the axis of the rotors.

The reliable functioning of all known forms of tubeless stranding machines in which the wire is guided along a sinusoidal path is determined by the extent to which it is possible to maintain the material that is to be stranded on the ideal flight curve. This ideal flight curve is achieved if the elongate material can be drawn from the pay-off reel to the stranding point without any contact or with minimum contact with the guide points.

A requirement for achieving this condition is that the tensile force applied to the wire should be precisely correlated with the geometry of the machine, the elongate material to be stranded and the rotational speed of the rotor at any particular time. In practice, this ideal condition is not achieved with precision.

The most important interference factors are variation of the braking force applied at the pay-off reel, variations in the degree of friction at the guide points, change in the friction ratio, and variation in the speeds of the rotor and therefore in the magnitude of the centrifugal force applied to the material during the start-up and braking phases of the rotor.

Because of these interferences, there occur the following two limiting cases which cause breakage of the elongate material to be stranded or at least greatly inhibit performance of the stranding operation; first, when the tensile force applied to the wire is too great, the material is pulled too taut in the flight curve. The wire is pulled hard over the guide points, the resultant friction intensifies this condition from one reel to the next, and the wire finally breaks. This danger exists in all the known arrangements particularly during the start-up phase, because of the fact that the centrifugal force has not fully developed since only when the centrifugal force is at its greatest does it cause the wire to be moved outwards relative to the rotational axis so as to lift it from the guide points under the required tensile force.Secondly, if the tensile force applied to the wire is too low, the flight curve extends so far outwardly that it becomes unstable, the wire strikes the surrounding structure (protective hood) and likewise causes the wire to break.

Solutions are known which aim at influencing the above-mentioned interference factors in such a way that the operation is stabilized.

In German Patent Specification OS 2164131, Application No. P.2 164 131.6- 22 of 23rd December 1971, there is described an apparatus for controlling the tensioning of the wire, which apparatus operates in dependence upon the reel brake and the position of a lever acted upon by the force exerted by the wire. The lever is urged by a torsion spring in the direction opposite to that of the force exerted by the wire and is set to correspond with a mean value. Since the said lever is coupled to the reel brake, the tension in the wire is dependent upon the increasing or diminishing frictional force of the reel brake.This method of controlling the force exerted by the wire only influences the interference factors caused by the run-off reel, such as run-off angle and coil diameter, whereas none of the other interference factors occurring during further guiding of the wire is dealt with. An approximately uniform force in the wire along the rotor such as is necessary for creating an ideal flight curve is not achieved to a satisfactory extent. Frequent correction of the brake setting is necessarv.

On the other hand however it is also known that brake constructions of this kind at best only provide an accuracy in the constancy of the set value of + 10% even in the best designs. Influencing of the starting-up phase in a positive manner is not possible at all when this solution is used. This means that the machine cannot be started up in the case of materials such as copper that cannot withstand heavy tensile loading.

A further known form of high-speed stranding machine, as disclosed in East German Patent Specification No. 115169, Application No. AP D 07 b/182 782, is aimed at limiting the throw of the flight curve by arranging what is called a guide ring on the projecting ends of the rotor sections in such a way that when the flight curve is too pronounced, the ring produces a self-regulating effect, i.e. stabilization, by way of the increasing friction that occurs on the ring. In this connection it has been found that the small looping angle at the inner face of the ring is able to cause only a very slight change in the force to which the wire is subjected.

It is doubtful whether the self-regulation that is claimed to take place suffices. Furthermore, the other dangerous limiting case of excessive wire tension and the critical start-up phase are not positively influenced. In these cases, because of the still inadequate centrifugal action, the reversal points act as brakes which permit the force in the wire to increase beyond the permitted value along the rotor.

Consequently cracks in the wire occur which have an adverse effect upon the performance of the stranding machine or which prevent the normal speed of rotation from being reached.

According to the present invention there is provided a tubeless stranding machine of the type in which the elongate materials pulled off the supply reels are guided along the machine in a sinusoidal path and form free flight curves between indivdual rotor sections of the machine, inner and outer wire-guide members being arranged for a strand in each rotor section, each inner wire-guide member consisting of a rod having a longitudinal slot therein, the base of said slot describing a curve, each outer wire-guide members being arranged in a flange-like end of a rotor section and each consisting of a guide roller and a hollow wire guide, the hollow wire guide having- a wedge-shaped guide groove which extends radially outwards from an axis of the guide.

Also, according to the invention, the rod of each inner guide is arranged in a bore extending obliquely outwardly from the axis of the rotor section. The periphery of the guide roller of each outer wire-guiding member extends into the hollow of the hollow wire guide. The wire coming from the various pay-off reels passes along the axis of the rotor, along the longitudinal slot in the rod of an inner wire-guide member and around the curve in the slot, into the outer wireguiding elements. During the start-up phase of the machine and because of the immediately effective pull-off force and the still absent centrifugal effect, the wire is applied to the guide roller of the outer guiding elements. Thus, only the rolling friction, which is of low magnitude, becomes effective.The resistance at the reversal points thus remains low, and the force applied to the wire falls within the permissible range. As the speed of rotation of the machine increases and the centrifugal force applied to the guided wire becomes greater, the wire lifts from the guide roller and forms a flight curve which corresponds to the force occurring in the wire.

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 general side view of a tubeless stranding machine, Figure 2 shows, in section, part of a rotor section of the stranding machine having an inner wire-guide member, Figure 3 illustrates, in section, part of the rotor section with an outer wire-guide element, and Figure 4 is an end view of the outer end face of a guide nipple.

Referring to Figure 1, the tubeless stranding machine consists of a number of rotor sections 2, each mounted in a support stand 1, and supports, such as cradles, carrying bobbins, spools or reels 3 are mounted between the rotor sections 2. Also mounted in each of the stands 1 is a transmission drive shaft 4 which drives the several rotor sections 2 in synchronism. The transmission shaft 4 is in its turn driven by an electric motor 5, and at the same time the shaft 4 drives a pull-off unit 6. The chain-dotted lines indicate the sinusoidal path of travel of the wires 7 along the rotor axis.

Referring to Figure 2, the inner wire-guide member of each rotor 2 consists of a rod 9' fitted in a bore 8 which extends obliquely and outwardly from the axis of the rotor section 2. The rod 9 has a longitudinal slot 10, the base 11 of which slot forms a curved surface having a large radius of curvature.

An outer wire-guiding element (Figures 3 and 4) is arranged, in the flange-like ends 12 of each rotor section 2, and for each wire 7 it consists of a guide nipple 13 which has a longitudinal bore 14, the diameter of which bore increases from the middle outwards towards the forward end face of the guide nipple 13. Extending into the longitudinal bore 14 is the periphery of a guide roller 15 which is mounted in each of the ends 12 of the rotor section 2 and can be slightly rotated towards the middle of the rotor; this roller 15 itself froms part of the inner wall of the guide nipple 13.That portion of the wall of the longitudinal bore 14 disposed opposite the guide roller 15 is provided with a radially outwardly extending guide groove 16 which is wedge-shaped and narrows towards the outlet, this groove 16 beginning at the middle of the longitudinal bore l4 and increasing in depth towards the outlet. The geometrical disposition of the internal guide and outer wire-guiding element is such that when the wire acquires the ideal flight curve, the wire moves through the inner guide with the minimum of frictional resistance, and through the guide nipple of the outer guide without friction i.e. without contact.The mode of operation of the rotor and its wire-guides in accordance with the invention is as follows as regards the start-up phase and the operating position: During the start-up phase, no flight curve is formed along the wire because of the absence of or production of inadequate centrifugal forces and because the pull-off force immediately becomes effective. A relatively short length of the wire 7 lies on the curved base 11 of the longitudinal slot 10 in the rod 9 and, at the end 12 of the rotor, is only in contact with the peripheral surface of the guide roller 15. Since the frictional resistance is very low, particularly due to the rolling resistance of the guide roller 15, only a very slight increase in the force in the wire occurs at these reversal points during the start-up phase.Consequently the force applied to the wire is low and fewer cracks occur in the wire compared with known arrangements. In the operating condition of the high-speed stranding machine, i.e. when a flight curve is formed under the action of the centrifugal force applied to the wire 7, the guide rollers 15 again function as guide elements when excessively great forces occur in the wire i.e.

when an inward deviation from the ideal flight curve occurs. Because of their slight frictional resistance, the rollers prevent excessive increase in the force in the wire from the one guide point to the next, and they therefore also prevent the occurrence of frequent cracks in the wire. In the event of there being too little tension in the wire, i.e. when the material to be stranded deviates outwardly from the ideal flight curve, the wire bears on the guide nipple 13 and, as the flight curve is thrown further outwards, the wire 7 enters the wedge-shaped groove 16. In this way an effective frictional effect is achieved which prevents further outward movement of the flight curve because of the resulting increase in the force in the wire.

A condition of equilibrium between the frictional force on the faces of the wedge, the original force in the wire and the centrifugal force is established, so that thereafter the operation can be stabilized. By varying the wedge-angle in the groove 16, maximum adjustment of the force in the wire can be achieved in dependence upon the type of material to be stranded, its diameter, the speed of the rotor, the co-efficients of friction and other parameters.Generally, the present arrangement deals so positively with the problem of the ideal level of the downwardly and upwardly varying tensile force in the wire as well as that associated with the special conditions that occur when the rotor is starting up that a stranding operation that is stable as regards the load on the material to be stranded and the frequency of cracks in the wire is less compared with machines having reel-braking systems.

WHAT WE CLAIM IS:- 1. A tubeless stranding machine of the type in which the elongate materials pulled off the supply reels are guided along the machine in a sinusoidal path and form free flight curves between individual rotor sections of the machine, inner and outer wire-guide members being arranged for a strand in each rotor section, each inner wire-guide member consisting of a rod having a longitudinal slot therein, the base of said slot describing a curve, each outer wire-guide member being arranged in a flange-like end of a rotor section and each consisting of a guide roller and a hollow wire guide, the hollow wire guide having a wedge-shaped guide groove which extends radially outwards from an axis of the guide.

2. A tubeless stranding machine as claimed.

in claim 1, in which the rod of each inner guide is arranged in a bore which extends obliquely outwards from the axis of the rotor section.

3. A tubeless stranding machine as claimed in claim 1 or claim 2, in which the periphery of the guide roller of each outer wire-guide member extends into the hollow of the hollow wire-guide.

4. A tubeless stranding machine, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. bore 14 is the periphery of a guide roller 15 which is mounted in each of the ends 12 of the rotor section 2 and can be slightly rotated towards the middle of the rotor; this roller 15 itself froms part of the inner wall of the guide nipple 13. That portion of the wall of the longitudinal bore 14 disposed opposite the guide roller 15 is provided with a radially outwardly extending guide groove 16 which is wedge-shaped and narrows towards the outlet, this groove 16 beginning at the middle of the longitudinal bore l4 and increasing in depth towards the outlet.The geometrical disposition of the internal guide and outer wire-guiding element is such that when the wire acquires the ideal flight curve, the wire moves through the inner guide with the minimum of frictional resistance, and through the guide nipple of the outer guide without friction i.e. without contact. The mode of operation of the rotor and its wire-guides in accordance with the invention is as follows as regards the start-up phase and the operating position: During the start-up phase, no flight curve is formed along the wire because of the absence of or production of inadequate centrifugal forces and because the pull-off force immediately becomes effective. A relatively short length of the wire 7 lies on the curved base 11 of the longitudinal slot 10 in the rod 9 and, at the end 12 of the rotor, is only in contact with the peripheral surface of the guide roller 15.Since the frictional resistance is very low, particularly due to the rolling resistance of the guide roller 15, only a very slight increase in the force in the wire occurs at these reversal points during the start-up phase. Consequently the force applied to the wire is low and fewer cracks occur in the wire compared with known arrangements. In the operating condition of the high-speed stranding machine, i.e. when a flight curve is formed under the action of the centrifugal force applied to the wire 7, the guide rollers 15 again function as guide elements when excessively great forces occur in the wire i.e. when an inward deviation from the ideal flight curve occurs. Because of their slight frictional resistance, the rollers prevent excessive increase in the force in the wire from the one guide point to the next, and they therefore also prevent the occurrence of frequent cracks in the wire. In the event of there being too little tension in the wire, i.e. when the material to be stranded deviates outwardly from the ideal flight curve, the wire bears on the guide nipple 13 and, as the flight curve is thrown further outwards, the wire 7 enters the wedge-shaped groove 16. In this way an effective frictional effect is achieved which prevents further outward movement of the flight curve because of the resulting increase in the force in the wire. A condition of equilibrium between the frictional force on the faces of the wedge, the original force in the wire and the centrifugal force is established, so that thereafter the operation can be stabilized. By varying the wedge-angle in the groove 16, maximum adjustment of the force in the wire can be achieved in dependence upon the type of material to be stranded, its diameter, the speed of the rotor, the co-efficients of friction and other parameters.Generally, the present arrangement deals so positively with the problem of the ideal level of the downwardly and upwardly varying tensile force in the wire as well as that associated with the special conditions that occur when the rotor is starting up that a stranding operation that is stable as regards the load on the material to be stranded and the frequency of cracks in the wire is less compared with machines having reel-braking systems. WHAT WE CLAIM IS:-

1. A tubeless stranding machine of the type in which the elongate materials pulled off the supply reels are guided along the machine in a sinusoidal path and form free flight curves between individual rotor sections of the machine, inner and outer wire-guide members being arranged for a strand in each rotor section, each inner wire-guide member consisting of a rod having a longitudinal slot therein, the base of said slot describing a curve, each outer wire-guide member being arranged in a flange-like end of a rotor section and each consisting of a guide roller and a hollow wire guide, the hollow wire guide having a wedge-shaped guide groove which extends radially outwards from an axis of the guide.

2. A tubeless stranding machine as claimed.

in claim 1, in which the rod of each inner guide is arranged in a bore which extends obliquely outwards from the axis of the rotor section.

3. A tubeless stranding machine as claimed in claim 1 or claim 2, in which the periphery of the guide roller of each outer wire-guide member extends into the hollow of the hollow wire-guide.

4. A tubeless stranding machine, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.