IL24788A - Manufacture of wire strands - Google Patents

Description

C O H E N Z E D E K & S P I S B A C H R EG D . PATE N T A TT O R N E YS 24, LEVONTIN STR., P, O. B. 1169 T E L - AV I V P A T E N T S & D E S I G N S O R D I N A N C E 13972/65 SPECIFICATION MANUFACTURE OF R'XRg STRANDS BRITISH ROPES LIMITED , pa' British Company, of Warmsworth Hall, Doncaster, Yorkshire, - HEREBY DECLARE ihe nature of this invenfion end in what manner the same is to be performed to be particularly described and ascertained in and by the following statement: It is well known that a plurality of round wires can be caused to twist together in the form of a strand when the wires are given a rotary motion about their respective longitudinal axes, while at the same time the strand thus forming is allowed to rotate about its own axis.

This principle has been put into effect in various known types of apparatus, but has usually involved the use of supply packages in the form of bobbins, each of which is rotated bodily about an axis perpendicular to the bobbin axis. By leading the wires unwound tangenti ally from such bobbins into a rotating device which pulls the wires at a speed related to the rate of rotation of the device, a strand of conventional type is caused to form.

This invention relates to methods whereby the rotation required for forming round wires into such a strand can be imparted to the individual wires without having to rotate the supply packages.

As is well known, the rate of rotation of the individual wires must; be approximately equivalent to the rate of rotation of the strand itself, thus causing each wire to be rotated about its owrflongitudinal axis once for each lay length of the strand. If the wire supply packages are not caused to rotate at this speed, and the wires are of material with a high modulus of rigidity, such as hard-drawn steel wire, the discrepancy in rotations will accumulate between the strand plying point and the wire supply packages. This results in torques which are liable to cause kinks in the wires if .tension is not carefully and constantly maintained.

~~ Proposals have been made to rotate each wire about its own axis while passing from the respective package to of rigidity there remains a risk of kinks occurring adjacent to the packages.

Methods according to the present invention resemble previous methods in that they comprise supporting a plurality of supply packages of round wire, leading wires from respective supply packages along respective paths to a plying point, rotating each wire about its own axis while passing from the respective package to the plying point, and pulling a resultant plied strand away from the plying point while the strand rotates.

Methods according to the present invention advance on previous methods by supporting the packages on means in stationary attitudes, by restraining rotation of each wire at a first point between the respective package and the plying point, and by positively rotating each wire at a second point between the respective first point and the plying point at a speed so related to the speed of rotation of the strand and the rate of pulling of strand away from the plying point, that each wire undergoes elastic and plastic torsional deformation on passing the first point, and undergoes at least partial elastic recovery on passing the second point.

The present invention also includes apparatus for carrying out these methods.

The apparatus include, for each wire, a rotary twisting means capable of applying rotation to a portion of wire lying at any instant between the package and the plying device, and, between the twisting means and package, an isolating means in a stationary attitude, the isolating means being capable of preventing rotation from the twisting means passing to the package. constitute what may be termed a torsion inductor, interposed between a wire supply package and the plying point, which can cause an individual wire to rotate about its own longitudinal axis at a speed not greatly different from the speed of rotation of the strand about its axis, while at the same time preventing rotation from passing back to the wire leading from the supply package.

The fact that each supply package is stationary has the advantages that there are no severe limits on size, weight or type of package, and also that access to the packages is possible while the stranding machine is running.

Various further features which are of advantage, but which are not essential, will be mentioned in the course of the following description of particular apparatus and methods embodying the invention, which are by way of examples. The apparatus are shown in the accompanying drawings, in which: - Figures 1A and IB together make up a diagrammatic side elevation of a complete machine for making wire strands, the two Figures joining on the line X-X; Figure 2 shows two of the torsion inductors, one in side elevation and one in vertical longitudinal section; Figure 3 is a plan view of one torsion inductor tvith parts in horizontal section; Figure is a vertical longitudinal section of a slightly modified torsion inductor; Figures 5 and 6 are diagrammatic side elevations of two other forms of torsion inductor; and Figure 7 shows an alternative form of wire package.

In the machine shown in Figures 1A and IB, round wires 1 are led from supply packages 2, through individual plying device 6. A plied strand 8 is withdrawn from the plying device by a pulling means 10, and is collected by a take-up means 12. The whole machine, except for a take-up drum, is driven by a single motor 14 through a main shaft 16.

The strand may include a core 18 led from a pay-off device 20. This core may be a single wire, or may itself be a strand onto which the wires 1 are applied as an additional layer.

The packages 2 are supported by shafts 3 mounted on a stationary structure 5· The torsion inductors are supported by a stationary structure 7· These torsion inductors are more fully described later.

The plying device 6 has a positive drive by a toothed belt 22 direct from the main shaft 16. The plying device consists of a rotating die block 24 with a bore, the entry to which defines the actual plying point. The device may also include a so-called "postformer" , for example, as shown, a cage 26 which rotates with the die and carries a series of small rollers 28 which nip the strand. These assist in making the strand straight and of uniform construction, and in neutralising locked-up torsional stresses. Close "upstream" of the die block 24 is a stationary plate 30 containing holes regularly spaced around a circle, which serves as a guide for the wires 1. Also close upstream of the die block there may be means (not shown), e.g. a fixed pipe passing between the wires 1, for applying a thin coating of lubricant to the core 18.

The pay-off device 20 delivers the core 18 to the die block and imparts rotation to the core at a speed related to that of the die block. For this purpose, the device speeds about their common horizontal axis by positive drives 36, 38. The trunnions carry, via bearings (not shown), a cradle 40 which is stabilised against rotation by a weight 42, and which supports a drum 44 carrying core material. The trunnions carry guides 46 and 48 respectively, by which the core 18 is led to the left and then to the right so as to be delivered through a bore in the right-hand trunnion 34 with a rotary motion at twice the speed of the trunnions. There is a brake (not shown) on the drum 44 to maintain tension in the core 18. The guides 46, 48, and also stationary guides 50, 5 , are of construction such that the core can move longitudinally and at the same time rotate while passing round the guides. The speed of rotation of the trunnions may be altered by exchanging one pulley in each drive 36, 38 for a pulley of another size .

If the core is a single wire, then it may alternatively be supplied from a package 2 through a torsion inductor 4 similar to those which supply the outer wires 1, but the inductor for the core wire may rotate at a different speed.

The pulling means 10 has trunnions 54, 56 which support a frame 58. The trunnion 56 is rotated at the same speed as the plying device 6, by a positive drive 60.

The strand 8 passes axially through the trunnion 5^-, several times around a drum 62, and axially through the trunnion 56, being guided by pulleys 66. The drum 62 is driven from the main shaft 16 through a variable-ratio gear 64, a hollow shaft 0 concentric with the trunnion 54, and gearing 68. By suitable setting of the variable- -ratio gear 64, the drum 62 is caused to move the strand through the pulling means 10 at the desired linear speed.

The take-up means 12 includes trunnions 76, 78, positive drives 80, 82 from a shaft 84-, which is driven from the main shaft 16 by a variable-ratio gear 86. The trunnions 76, 78 support a cage 87 carrying guides 88, 89, 90. Within the cage, and supported by bearings (not shown), is a cradle 92 which is weighted so as not to rotate. The cradle carries, on a transverse axis, a take-up drum 94 onto which the strand 8 is wound. The drum is driven by gearing, not shown, from a shaft 96 coaxial with the trunnion 76. This shaft 96 is driven by a separate electric motor 8 of constant-torque type. The cradle also carries means, not shown, for traversing the strand to and fro across the drum 9 so as to build layers of turns of strand on the drum.

The components of the machine thus far described in detail are not, in themselves, parts of the present invention, but provide the context for the torsion inductors now to be described.

The number of package -supporting shafts 3 and torsion inductors 4 in the machine is made sufficient for the largest number of wires that may need to be handled, for example up to forty-three. Figures 2 and 3 show the construction of the torsion inductors in detail.

Each torsion inductor is, for convenience, made as a unit, with a base plate 102, fixed to a vertical pillar 104 which is part of the stationary structure 7. The plate supports three pulleys 106, 108, 110 on fixed axes, and also supports two bearings 112, 114 for trunnions 116, 118 on opposite ends of a rotary carrier constituted by a plate 120. The plate 120 supports two pulleys 122, 124, which have their grooves in a common plane containing the axis Y-Y of the trunnions 116, 118, and have their 124 constitute twisting means, and the pulleys 106, 108 constitute isolating means. The fact that the axes of the two pulleys 122, 124 of the twisting means intersect the carrier axis Y-Y means that the pulleys do not require to be counterbalanced. The carrier itself is counterbalanced by masses 136 on the free ends of the studs 138 on which the pulleys 122, 124 are journalled.

A wire 1, as shown in broken line in the lower half of Figure 2, is led from the supply package 2 (see Figure 1) to the pulley 106, once around the pulley 106, then to the pulley 108, and more than once around it, and through the trunnion 116 to the pulley 122. Under most conditions, two turns around the pulley 108, with suitable tension in the wire as described later, will prevent twist in the wire downstream of the pulley 108 from passing to the wire upstream of the pulley 108. The torsion of the wire downstream of the pulley will cause the wire as it leaves the pulley to lie to one side of the groove of the pulley. Which side will depend on whether the torsion is right-handed or left-handed.

When preparing the machine for operatio , the turns should be laid round the pulley 108 in whichever order will ensure that the torsion will not cause the outgoing turn to jam underneath the incoming turn.

In the twisting means, the wire is led once around the pulley 122, then to the pulley 124 and once around it, through the trunnion 118, and over the pulley 110, which acts as a guide from which the wire is led to the plying device. Within each trunnion is a grooved guide 126, 128, to deflect the wire to and from the axis Y-Y. The pulleys 106, 108, 110 are all tangential to this axis. as shown in Figure 4, so that the wire gyrates, and sweeps out a cone at each end of the twisting means. The wire passes through an oblique bore 1 0 in each trunnion.

Ill the twisting means are rotated by positive drives from the main shaft 16 (Figure 1A), constituted by a system of double pulleys 130 and toothed belts 132 (Figure 1A) , through a variable-ratio gear 134-· When the twisting means is rotated, by drive applied to a double pulley 130, and at the same time the wire is moved axially (to the right as seen in the Figures) by the action of the pulling means 10 (Figure IB), then the wire is continuously twisted as it leaves the pulley 108. As the wire leaves the pulley 124 it is rotating about its own axis. The angle of embrace on the pulley 110 is not so great as to prevent rotation of the wire.

If the speed of rotation on leaving the pulley 124 is different from the speed of rotation of the wire on reaching the plying point, then the difference involves continuous twisting of the wire as it leaves the pulley 124. In the normal use of the machine, the speed of rotation of the twisting means is so selected that twisting occurs on leaving the pulley 124 in the opposite sense from, and at a slower rate than, the twisting on leaving the pulley 108.

Experiments have shown that steel wires twisted to the extent of anywhere between about 2 and 10 twists per length equal to 100 times the diameter of the wire undergo both elastic and plastic deformation, and on the release of twisting torque there is elastic recovery.

Experiments have also shown that the tensile strength to break of a wire is not seriously affected by plastic The twisting on leaving the pulley 108 causes both elastic and plastic torsional deformation of the wire; the twisting on leaving the pulley 124 involves at least partial elastic recovery.

Following are two examples of conditions of operation of apparatus according to the present invention intended to produce strand in which the individual wires have no elastic torsional stress in them. In each case the wires are of hard-drawn high tensile steel of the type usually used for rope-making, namely wire having a low limit of proportionality on its stress/strain diagram. With such wire, the elastic recovery can be taken as about 1 twist per length equal to 100 diameters. This is a maximum figure, and a somewhat lower figure, say 3/4 twist (270°) per 100 diameters, could also be used in calculations. Variation in the tensile strength within the range of 80 to 120 tons is found to have little effect on the conditions. If the wire is of a type with greater elastic recovery, then the ratio of the speed of rotation of the torsion inductors to the speed of rotation of the strand will require to be greater.

Geometrical considerations show that in laying a wire in one turn of a helix at an angle » the rotation of the wire is 360° . sec EXAMPLE A Wire diameter - outer six = 0.022 100 x d = 2.2' centre one = 0.025 Lay length = 0.50" angle 16°27' secant 16°27' = 1.0482 helix length = 0.5241" Rotation Strand 360° to produce one strand lay of 0.500" Wire 345°16' to produce one helix of 0.524-1" Number of helices in one hundred wire diameters 2.20 - 0.52 1 = 4.198 say 4.2 Torsional displacement of strand = 4.2 x 360° = 1512° Torsional displacement of wire required to produce strand from 2.20 inches of 0.022" of outer wire = 345°16' x 4.2 = 1450°7' Additional twist, cancelled by later elastic recovery = 360° Total = 1810°7' = 5· 3 revolutions (This represents about 4 plastic torsions in a length of 100 wire diameters.) Ratio of rotation of torsion to inductors/rotation of strand = 1810 - 151 = 1.1965 say 1.20 EXAMPLE B Wire diameter - outer four = 0.021 centre one = 0,024 Lay length = 0,100" angle = 5-_° 4' secant 54°44' = 1.7319 helix length = 0.1732 Rotation Strand 360° to produce one strand lay of 0.100" Wire 207°52 ' to produce one wire helix of 0.1732 " Number of helices in one hundred outer wire diameter 2.1 - 0.1732 = 12.126 Torsional displacement of strand = 12.126 x 360° = 4365° Torsional displacement of wire required to produce strand from 2.10 inches of 0.021 outer wire = 207°52 ' x 12.126 = 2511°15 ' Additional twist, cancelled by later elastic recovery = 360° Total = 2871°15 ' = 7 · 97 revolutions (This represents about 7 plastic torsions in a length of 100 wire diameters.) Ratio of rotation of torsion inductors to rotation of strand = 2871 - 4-365 = 0.658 say 0.66 Reverse and simple bend fatigue testing of strands made by these methods, and of ropes composed of such strands, have demonstrated that they are not inferior to strands and ropes formed by traditional methods. Hence, it is apparent that the induction of a limited amount of plastic torsion in the wire is not deleterious to the quality of strands or ropes.

It is desirable that the tension of each wire 1 as it leaves its acka e 2 should be low. If there is the package may tend to bury itself among later turns and become caught. On the other hand, it may be desirable to ensure that none of the wires can become slack at any point, as slackness, even for a short period, might lead to the formation of a loop, which would then contract into a kink .

Accordingly, depending on what nature of package 2 is being used, known devices for applying tension and for maintaining uniformity of tension may be included. For example in Figure 1A the packages 2 are shown as bobbins mounted to rotate about fixed shafts 3> the wires 1 being pulled tangentially off the bobbins. There may, as shown in the case of the lowest bobbin, be an adjustable gentle friction brake 160 to create tension, and a weighted pulley 162 to accommodate irregularities in the speed at which wire comes off the bobbin, and thus maintain uniformity of tension. Uniformity of tension may also assist uniformity in the structure of the plied strand.

The pulleys of the torsion inductor preferably have diameters greater than 100 times the wire diameter. The unsupported length of wire between the isolating means and the twisting means is preferably less than 500 times the wire diameter. Bearing in mind that the same apparatus is useable with a range of sizes of wire, the apparatus is preferably arranged so that the unsupported length is less than 3 times the pulley diameter.

The guide pulleys between the twisting device and the plying device (e.g. the pulleys 110 in Figures 2 and 3) should have a diameter not less than that of the preceding pulleys, and the wire should embrace the guide pulleys through an arc of less than 90°. A guide immediately to bend the wires through a sharper curvature than the pulleys, thereby bending each wire as it passes and so deforming it into a helix, by reason of the simultaneous rotation of the wire. The hei-cal shape may assist uniformity in the structure of the plied strand.

The two numerical examples given above are of conditions of operation intended to produce no elastic torsional stresses in the wires in the plied strand. Howev for many purposes the presence of some elastic stress in the wires, in the direction tending to make the wires in the strand cling to the core, is not significant, and therefore some deviation from theoretical conditions is permissible. Moreover, if the use to which the strand is to be put, for example to make some particular type of rope for some particular duty, makes it desirable to ensure that some elastic stress is present, either of the same hand as the lays or of the opposite hand, this can be achieved within the scope of this invention, by appropriate adjustment of the conditions. Some of the torsional elastic recovery of the wires may occur within the strand after the wires have been plied together. For example, in the apparatus shown in Figure IB, this may be brought about by adjustment of the variable-ratio gear 86 driving the cage of the take-up means 12. Furthermore, some of the torsional elastic recovery of the wires may occur during the "closing" of several strands together to make a rope .

Figure 5 shows a torque inductor in which the torque isolating means and the twisting means each include only one pulley 136, 138 respectively. It is necessary to take several turns of wire round each pulley. The pulley 138 and is therefore counterbalanced by a weight 142.

Figure 6 shows the possible use of larger numbers of pulleys, 144, 146 respectively, in the torque isolating means and in the twisting means.

Figure 7 shows another form of package in which each wire 1 may be supplied. The wire is in loose coils 150 , is the form in which it is usually collected at the output end of a wire-drawing machine. The coils, which are one continuous length of wire, are supported on a cage of bars 152 , which are fixed at their lower ends to a turntable 153 , and which are also joined together by a top member 155 · The turntable is rotatably supported on a base 154- , from which a fixed shaft 156 extends upwards. The shaft carries an adjustable gentle friction brake 1 8 acting on the top member, and hence on the coils.

The packages, instead of rotating about an axis, may be entirely stationary, the wire being removed over one end of the package. The tension should be continuously maintained just sufficient to prevent the slight twist produced (one rotation per turn of wire on the package) from causing kinks in the wire on its way to the isolating means .

Claims (16)

HAVING HOW particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is :

1. A method of manufacturing a wire strand, comprising supporting a plurality of supply packages of round wire on means in stationary attitudes, leading wires from respective supply packages along respective paths to a plying point, pulling a resultant plied strand away from the plying point while the strand rotates, restraining rotation of each wire at a first point "between the respective package and the plying point, and positively rotating each wire about its own axis at a second point between the respective first point and the plying point at a speed so related to the speed of rotation of the strand at the plying point, and the rate of pulling of strand away from the plying point, that each 'wire undergoes elastic and plastic torsional deformation on passing the first point, and undergoes at least partial elastic recovery on passing the second point.

2. A method according to claim 1, in ivhich each wire undergoes between 2 and 10 twists per length equal to 100 times the diameter of the wire.

3. - A method according to claim 1 or claim 2, in which each wire "between the first point and the second point has an unsupported length not exceeding 500 times the diameter of the wire .

4. . A method according to any of claims 1 to 3, in which the rotation is restrained by passing each wire once round a first pulley and twice round a second pulley.

5. A method according to any of claims 1 to 4, in which the wires are of high tensile steel.

6. A method according to any of claims 1 to 5, in which the wires are plied around a core which is delivered to the plying point rotating at a speed related to the speed of the strand.

7. · A method according to any of claims 1 to 6, in which the supply packages are bobbins mounted to rotate about fixed axes, and the wires are pulled tangentially off the bobbins.

8. Apparatus for manufacturing a wire strand, comprising a plying device, a plurality of means in stationary attitudes for supporting supply packages, a plurality of directing means each defining a path for a wire from a respective one of the packages to the plying device, each directing means including, in sequence from the package to the plying means, firstly an isolating means in a stationary attitude and secondly a rotary twisting means, the twisting means being capable of applying rotation to the portion of wire lying at any instant between the isolating means and the twisting means, the isolating means being capable of preventing this rotation passin towards the package, means for pulling plied strand away from the plying device, and means for positively driving the twisting means and the pulling means at speeds in a predetermined ratio.

9. Apparatus according to claim 8, in which each twisting means includes at least one pulley mounted in a rotary carrier, the groove of the pulley being in a plane containing the axis of rotation of the carrier.

10. Apparatus according to claim 9, n which each isolating means includes at least one pulley tangential to the axis of rotation of the respective carrier.

11. Apparatus according to claim 10, in which there are two pulleys in each isolating means, in a common plane, and two pulleys in each twisting means, in a common plane.

12. Apparatus according to claim 11, in which the axes of the pulleys in the twisting means intersect the axis of the carrier.

13. Apparatus according to any of claims 8 to 12, in which the plying device is rotary, and the speeds of the twisting means and of the pulling means are individually adjustable in relation to the speed of the plying device.

14. Apparatus according to claim 13, including means for supplying a core to 'the plying device , and for rotating the core at a speed related to the speed of the plying device.

15. A strand produced by a method according to any of claims 1 to 6 or by an apparatus according to any of claims 8 to 14.

16. A torsion inductor substantially as described with reference to Figures 2 and 35 Figure , Figure 5, or Figure 6 of the accompanying drawings. 3BATID THIS 8th day