GB2119420A

GB2119420A - Wire stranding

Info

Publication number: GB2119420A
Application number: GB08311796A
Authority: GB
Inventors: Reginald James Twist
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1982-04-30
Filing date: 1983-04-29
Publication date: 1983-11-16
Also published as: GB8311796D0

Abstract

A method of, and apparatus for, helically laying-up together at least two wires (2) comprises winding the wires on to a common spool (1) in such a way that the wires on the spool are of substantially the same length; mounting the spool on a first shaft (3) rotatably driven about its longitudinal axis; drawing the wires from the spool each at substantially the same substantially constant tension and guiding the wires at circumferentially spaced positions along, and through a guide plate (6) mounted at the downstream end of, a second shaft (5) rotatably driven about its longitudinal axis, the longitudinal axes of the shafts being substantially aligned, to cause each wire to follow a helical path; and drawing the wires through at least one die (7) to lay-up the wires together helically to form a strand or cable. <IMAGE>

Description

SPECIFICATION Wire stranding This invention relates to a method of and apparatus for helically laying-up together at least two bare or insulated wires, strands groups of bare or insulated wires or other flexible elongate elements (all such flexible elements hereinafter, for convenience, being included in the generic term "wire") to form a strand or cable.

According to the invention, an improved method of helically laying-up together at least two wires comprises winding the wires on to a common spool in such a way that the wires on the spool are of substantially the same length; mounting the spool on a first shaft rotatably driven about its longitudinal axis; drawing the wires from the spool each at substantially the same substantially constant tension and guiding the wires at circumferentially spaced positions along, and through a guide plate mounted at the downstream end of, a second shaft rotatably driven about its longitudinal axis, the longitudinal axes of the shafts being substantially aligned, to cause each wire to follow a helical path; and drawing the wires through at least one die to layup the wires together helically to form a strand or cable.

The improved method of the invention may be used in twisting two, three four or more wires or groups of wires together but, preferably, the rotatably driven shafts are of hollow form and the wires are helically wound or stranded around a flexible core being drawn in the direction of its length from a source of supply and through the rotatably driven shafts, guide plate and die or dies.

In the latter case, the improved method of the invention may be effected in tandem with and downstream of an extrusion line or other cable making process.

The flexible core may be a single wire or it may be strand or group of wires.

Preferably, the spool is detachably mounted on the first shaft and the wires are wound on the spool at a separate plant or plants.

The first and second shafts may be integral.

Where the spool is detachably mounted on the shaft, preferably the common shaft is dividable transversely at a position intermediate of its ends into said first and second shafts, the shafts being detachably coupled together and one or each of which can be moved lengthwise with respect to its longitudinal axis relative to the other to provide for mounting and dismounting of the spool. Where the spool is permanently mounted the arrangement must be such as to allow rewinding of the spool on the shaft.

To ensure that the wires are drawn from the spool each at substantially the same substantially constant tension, and to avoid a varying draw-off angle preferably the wires are drawn through a pivotally mounted wire follower operatively coupled to sensing means controlling movement of the spool in a direction lengthwise with respect to the first shaft axis, the arrangement being such that the wires are continuously drawn from the spool at a substantially constant draw-off angle, and preferably in a direction substantially normal to the first axis of the shaft. That is to say, the spool traverses in a direction lengthwise with respect to the first shaft axis so that the wires are drawn from the spool at a substantially constant tension and draw-off angle.Preferably the follower is so mounted that if the wire breaks the follower moves the sensing means to an extreme position to stop the rotation of the shafts.

Preferably, the wires are wound on the spool at the same time, e.g. from a multi-head wire drawing machine and, in addition to being so wound that the wires on the spool are of substantially the same length, preferably the wires are wound on to the spool each at substantially the same substantially constant tension.

Preferably, in their path from the spool to the guide plate carried by the second shaft, all of the wires pass through a tension control device that is common to all the wires and is adapted so to control the tension in each wire such that the tension in each wire is maintained at substantially the same constant value. The tension control device may take any convenient form and preferably automatically controls the speed of a motor drawing the wires from the spool and/or the speed of a motor, e.g. a torque motor, coupled to the spool and applying a braking force thereto.

The technique of employing a common tension control device to ensure that the tension in each wire is maintained at substantially the same value has the important advantage that it is easier to maintain constant a tension of, say, 200 gm in a group of four wires than to maintain constant a lower tension, of, say 50 gm in each of several single wires.

The means guiding the wires from the spool to the second shaft and, where present, the tension control device are preferably mounted on a flyer which is preferably secured to, and rotates with, the second shaft. Preferably, a single motor rotatably drives the second shaft, guide plate and flyer and, via a third (splined) shaft and, say, a oneway clutch, also rotatably drives the first shaft and the spool at substantially the same speed of rotation as one another. Additional rotational speed required by the spool and control of tension in the wires being drawn from the spool is provided by the additional motor, e.g. the torque motor, coupled to the spool which responds to signals from the tension control device and from, for example, a slip ring engaged by the flyer.

The invention also includes improved apparatus for helically laying-up together at least two wires by the improved method hereinbefore described.

Two or more improved apparatus of the present invention may be used in tandem with the longitudinal axis of the shafts of each apparatus being substantially aligned. Alternatively, two lines each comprising at least one improved apparatus may be associated with the same extrusion machine to accommodate for re-charging of the improved apparatus of one of the lines within the running time of the extrusion machine.

This coaxial arrangement of stranding reduces out-of-balance forces and facilitates loading of the spool.

The invention is further illustrated, by way of example, by the accompanying drawings in which: Figure 1 is a diagrammatic side view of the preferred apparatus; and Figure 2 is an end view in the direction X shown in Figure 1.

Referring to the drawings, the apparatus comprises a spool 1 having wound thereon at least two wires 2, the spool being mounted on a rotatable hollow first shaft 3; a flyer 4 mounted on a rotatable hollow second shaft 5; a guide plate 6 mounted at the downstream end of the second shaft; and a die 7.

A motor 8 rotatably drives the second shaft 5, guide plate 6, and flyer 4. The motor 8 also rotatably drives the first shaft 3 and spool 1 via a splined shaft 9 and a one-way clutch 10.

The spool 1 and first shaft 3 are mounted on a spool carriage 11 which is mounted on bearings 12 on linear bearing shafts 1 3. A carriage traverse actuator 14 acts on the spool carriage 11 to move the carriage in the direction of arrow X and in the reverse direction. The actuator 14 responds to signals received from a wire follower 1 5 pivotally mounted on the end of the flyer 4. The follower 1 5 is operatively coupled to a sensing device 1 6 which registers the draw-off angle of the wires 2, and moves the spool carriage 11 via the actuator 14, to ensure the draw-off angle remains substantially constant, preferably at 900 to the longitudinal axis of the first shaft 3.

A (secondary) torque motor 1 7 is also coupled to the splined shaft 9 driving the spool 1. The torque motor 1 7 responds to signals from a tension monitor 1 8 actuated by the wires 2 and mounted on the flyer 4, and/or a slip ring 1 9 engaged by the flyer, to cary the rotational speed of the spool 1 and hence control the tension in the wires 2. The tension monitor 1 8 also sends signals to the motor 8 to vary the rotational speed of the flyer 4 and second shaft 5, also to control the tension in the wires 2.

In use a flexible core 20 passes through the first and second shafts 3, 5, guide plate 6 and die 7.

Wires 2 unwound from the spool 1 pass over wire follower 1 5 and tension monitor 18, and through the second shaft 5, guide plate 6 and die 7.

Rotation of the second shaft 5 and guide plate 6 ensures the wires 2 are helically stranded around the flexible core 20.

Claims

1. A method of helically laying-up together at least two wires comprising winding the wires on to a common spool in such a way that the wires on the spool are of substantially the same length: mounting the spool on a first shaft rotatably driven abouts its longitudinal axis; drawing the wires from the spool each at substantially the same substantially constant tension and guiding the wires at circumferentially spaced positions along, and through a guide plate mounted at the downstream end of, a second shaft rotatably driven about its longitudinal axis, the longitudinal axes of the shafts being substantially aligned, to cause each wire to follow a helical path; and drawing the wires through at least one die to layup the wires together helically to form a strand or cable.

2. A method as claimed in Claim 1, wherein the rotatably driven shafts are of hollow form and the wires are helically wound or stranded around a flexible core being drawn in the direction of its length from a source of supply and through the rotatably driven shafts, guide plate and die or dies.

3. A method as claimed in Claim 1 or Claim 2, wherein the spool is detachably mounted on the first shaft and the wires are wound on the spool at a separate plant or plants.

4. A method as claimed in Claim 3, wherein the first and second shafts are integral, and the shaft is dividable transversely at a position intermediate of its ends into said first and second shafts which, the shafts being detachably coupled together and one or each of which can be moved lengthwise with respect to its longitudinal axis relative to the other to provide for mounting and dismounting of the spool.

5. A method as claimed in any one of the preceding Claims, wherein the wires are drawn through a pivotally mounted wire follower operatively coupled to sensing means controlling movement of the spool in a direction lengthwise with respect to the first shaft axis, the arrangement being such that the wires are continuously drawn from the spool at a substantially constant draw-off angle.

6. A method as claimed in Claim 5, wherein the draw-off angle is substantially normal to the axis of the first shaft.

7. A method as claimed in Claim 5 or Claim 6, wherein the follower is so mounted that if the wires break the follower moves the sensing means to an extreme position to stop the rotation of the shafts.

8. A method as claimed in any one of the preceding Claims, wherein the wires are wound on the spool at the same time, and have substantially the same length.

9. A method as claimed in Claim 8 wherein the wires are wound on to the spool each at substantially the same substantially constant tension.

10. A method as claimed in any one of the preceding Claims, wherein in their path from the spool to the guide plate carried by the second shaft, all of the wires pass through a tension control device that is common to all the wires and is adapted to control the tension in each wire such that the tension in each wire is maintained at substantially the same constant value.

11. A method as claimed in Claim 10, wherein the tension control device automatically controls the speed of a motor drawing the wires from the spool and/or the speed of a motor coupled to the spool and applying a braking force thereto.

12. A method as claimed in any one of the preceding Claims, wherein the means guiding the wires from the spool to the second shaft and, where present, the tension control device are mounted on a flyer.

13. A method as claimed in Claim 12, wherein the flyer is secured to, and rotates with, the second shaft.

14. A method as claimed in Claim 12 or Claim 13, wherein a single motor rotatably drives the second shaft, guide plate and flyer and, via a third shaft and a one-way clutch, also rotatably drives the first shaft and the spool at substantially the same speed of rotation as one another.

1 5. A method of helically laying-up together at least two wires as hereinbefore described, with reference to the accompanying drawings.

1 6. Apparatus for helically laying-up together at least two wires by the method claimed in any one of the preceding Claims.

1 7. Apparatus for helically laying-up together at least two wires as hereinbefore described with reference to, and as shown in, the eccompanying drawings.