Cable Production

Cable Production

 

the manufacture of metal and non-metallic (fiber) cables or ropes by means of appropriate technological equipment. The main operations of cable production are the rewinding of wire or yarn onto the spools of wire-drawing benches or reeling benches, the twisting of strands in a strand-twisting machine, and the twisting of cables in cable-twisting or braiding equipment.

Main technical parameters. Cable production technology is influenced by such parameters as the pitch of lay, the type of contact between wires in a strand and between strands in a cable, the direction and angle of lay, and the number of strands. The pitch of lay in strands for cables with point contact should not exceed 11 nominal diameters of circular or shaped strands; for cables with linear contact, it should not exceed 9 diameters; for six-strand cables, 6.5 diameters; for cables with shaped strands, 7.5 diameters; for cables with triple stranding, 7 diameters; and for the strands of a flat cable, 16 diameters.

The strands of cables with point contact are manufactured in one or more layers. There are not more than five wire layers in a strand; the total number of wires can be as high as 61 (and sometimes 91). Every layer in point-contact cables is laid at the same angle of lay; in linear-contact cables, various angles are used, usually in the same direction of lay. Spiral cables have alternating directions of lay for all or some of the layers (there may be as many as ten). The strands in cables with linear contact (not more than three layers) are made in a single production operation; the wires (not more than 48) are all laid in the same direction. The angles of lay relative to the axis of the strand are 12°-15° for point-contact cables and 16°-20° for linear-contact cables (for the outer layer). The angle of lay for the strands in a cable is chosen to approximate the angle of lay of the wires in a strand. To produce cables with one-way lay, cable-stranding machines are equipped with a planetary gear, which rotates the frames holding the loading spools and maintains tension on the strands to preserve the tightness of their lay.

For nonmetallic (fiber) cables, the strands are laid in a single operation, independent of the number of yarns. The pitch of lay for the strands of three-strand cables is 0.65-0.75 of the circumference; for hawser cables it is 0.85-1.0; and for cords it is 0.9-1.2. The angle of lay is 27°-33°. The direction of lay of the strands and of the cable or cord may differ. An anticorrosion grease is applied to wires and strands before laying. Finished products are also greased and are wound on a reel before shipment to consumers.

Metal cables. Metal cables are manufactured on strand-twisting and cable-twisting machines, which have identical functional diagrams and differ only in their dimensions and the number of loading spools (from three to 48). A metal or fiber core is located on the frame (base) of the machine, and wires or strands are twisted around it. The twisting part of the machine has a template, which distributes wires or strands, and a preformer for producing strands or cables that will not untwist. The strands or cables are shaped into a cone and compressed in a squeezing mechanism with dies. A roller mechanism straightens the cable array, which is then wound on reels or drums by a tensioning mechanism.

There are two types of machines, distinguished by the design of the laying member. In the rotor (basket) type, the spools in the frames are located between individual disks and rotate with the laying member. In the tube (cigar) type, the loading spools are located one behind the other in unbalanced carriages within a cigar-shaped tube (along its axis) but do not rotate with the tube. In both cases the spools rotate around their own axes as a result of force arising from the pull exerted on wires, yarns, or strands by the tensioning mechanism. In rotor machines the core passes through a hollow rotor shaft; in tube machines it passes along the inside surface of the tube. The direction of lay is determined by changing the direction of rotation of the laying member; the pitch of lay is adjusted by a choice of the speed of rotation of the laying member and the peripheral speed of the tensioning mechanism. For cables up to 20 mm in diameter, tube machines have a higher output than rotor machines and some cable-twisting machines. Braided and flat cables are produced on special machines and bench-type carriages. Nontwisted cables are installed by consumers at the site of use.

Nonmetallic cables. Nonmetallic cables are manufactured on machines called ropeways and on stationary strand-twisting and cable-twisting machines. In ropeways the yarns are successively pulled and twisted into strands up to 350 m long. Then, after having passed through the stationary front part and the movable part of the machine, the strands are slightly twisted and divided into groups of three or four on a carriage equipped with a rammer (a device for twisting the cable). The strands are given a cable lay and then a hawser lay by means of hooks mounted in the front part and the movable part of the machine. Ropeways are used in the manufacture of cables or cords of various diameters and up to 250 m long, using two or three standard sizes.

In stationary machines cables and cords are produced in one or two operations. In fiber-twisting machines, as distinguished from machines producing strands of wire, spools with yarn are located in spool holders and the laying member is combined with pulling and receiving mechanisms located within it. In modern machines one turn of the laying member (strander) results in the production of two pitches of lay in the strand, because of special strand loading (with an extra turn). Cable-twisting machines for cables made of fibrous materials differ from wire-cable twisting machines of the rotor type in the number of loading frames and the design of the planetary gear.

Small-diameter rope and cord products are made in a single operation (simultaneous production of strands and twisting into a cable), using combined cording machines and devices that consist of two combined twisting members, one for producing the strand and the other for laying the rope or cord. Halyards are made on braiding machines; nautical braided ropes are produced on special braiding machines.

REFERENCES

Bukshtein, M. A. Priadenie zhestkikh lubianykh volokon i proizvodstvo kruchenykh izdelii. Moscow, 1945. (Priadenie lubianykh volokon, part 3.)
Glushko, M. F. Stal’nye pod”emnye kanaty. Kiev, 1966.
Sergeev, S. T. Nadezhnos’i dolgovechnosVpod”emnykh kanatov. Kiev, 1968.
Bukshtein, M. A. Proizvodstvo i ispol’zovanie stal’nykh kanatov, 2nd ed.Moscow, 1973.

M. A. BUKSHTEIN

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