Steel cable is easy to everyday work that is almost not affected by discontinuities due to chafing of wire, which can lead to quite disastrous consequences, especially when performing responsible work.
By design, steel cable is a metallic product consisting of a twisted in a certain way similar strands (usually six) around the core. Cores are organic (hemp, polypropylene, sisal, jute) and metal. Each of the six strands, in turn, consists of a certain number of thin wires with spring properties, which will eventually take over the entire load, as well as provide a tightrope in general the necessary flexibility in carrying out lifting operations. The greater the number of wires in the strands, the rope is softer, more flexible and hardier.
Above all, steel cables have a number of various specifications (method and type of lay, the degree krutimosti and poise, the calculated values of ripping, etc.).
Application
Wire ropes are widely used in various industries including construction, industry, transportation, and household and business needs. Braided texture enhances the mechanical strength of metal wires have a low coefficient of expansion and low coefficient of torsion. In some cases, the cables can be supplied with shells made of PVC (latex, polyurethane and other synthetic materials), which significantly reduces the impact on the cable from the environment, protecting it from external influences. All this makes the ropes and steel cables suitable to various types of work.
On the scope of the tether is also influenced by its structure: it affects the cable stretching, strength, recommended load. If we consider the line in cross section, then the middle is the core - organic or synthetic, around which a certain order Formation strands of metal wire. Inside the strands can also be core. Number of strands around the core suite, and the number of wires in a strand itself determine the strength of the cable, the maximum allowable load and strain under the influence of dynamic loading. For example, cables with a diameter of 5 mm are used only for extensions, a maximum diameter of 22 mm - in elevators, lifting devices, cranes, with a diameter less than 26 mm - for rigging and fixing.
Galvanized wire is used to improve corrosion resistance wire.
Types of cross cable
Single-lay cables consist of a single strand, which has the same diameter wire in a spiral formation in one or more (up to four) layers around one of the wires. Number of wires and fibers in the strand is indicated in the characterization of rope sum of digits in which the first digit indicates the presence of a central wire, the second - the number of wires in the first strand from the center of the layer, the third - the second layer, etc.
Cables double lay produced twist several strands in one or two layers around a single metal, organic or mineral core.
Ropes of three strands swaddles without cores.
Rope lay triple twist of several cables. Ropes are made from a thin wire. They are much more flexible, but at the same time, weaker. Used mainly where you want the special flexibility, such as light lifting devices with a cable wound on the drums for hoists.
Steel cables have the right and left direction of lay of strands. In the first case of strands in a cable twist clockwise. The second - anti-clockwise.
By type of lay cables are one-sided, cross and a combined lay. In a one-way cable lay wire at an angle to the axis of the cable(б), a cross lay ropes - parallel to axis of the cable(а), combined with ropes lay - cross type(в).
Manufacturers produce cables with cross type (right) lay. They are the least susceptible to unwinding does not require special treatment and are most widely used on ships. Other species lay cables are manufactured only upon request.
Non-rotating cable, that work does not revolve around its axis, is used for rescue, hydrological and other studies.
Steel cables are rigid and flexible. Tight ropes are made from a small number of large diameter wires, one organic core or without him. They possess great strength. Flexible cables are made from a large number of thin wires and have one or more organic cores.
Measurement of wire rope
The thickness of the steel cable is measured by diameter in millimeters (mm) caliper. (а-right; б-wrong)
Working with steel cables and care
When accepting the cable should make a thorough external examination and test design. Inspection of the cable is to test his lay, which shall be uniform throughout its length. The cable must not be broken, overlapping, twisted and stretched weaker than the other wires. On the surface of the cable wires should not be dents, cuts and rzhavchiny.Tros must be round the entire length. Galvanized wire shall be sturdy, with no cracks. Strands of the cable should not be easing room. Organic cores do not have to allocate a lubricant and protrude from inside the cable. After the external examination in measuring cable and check it against the actual design data specified in the certificate, which is slightly untwist the end of the rope and count the number of strands of wires in the strands and the amount of organic cores, check the location of the strands in the cables and wires in the strands. The design of the cable must comply with these data.
Cables must meet the conditions of work. Hard line, for example, can not be used as a mooring, to pass through blocks, as it will rapidly deteriorate. Mooring, tugs and equipment lifting devices used flexible cable.
Rope wound around the drum during loading and unloading can not throw and put a strong shock, since it can damage the drum awry, and it is difficult to disentangle.
Unacceptable looping as pulling ropes, they form a room, dramatically lowering the strength of the cable and make it unusable. Loop should be carefully and correctly deploy, avoiding drawing poluzavernutoy loop. When blossom bight clew up for the free end while rotating the bay or a drum. (а-right; б-wrong)
Before the segment cut off from the bay steel cable to any length to avoid unwinding the cable imposes two brands of soft wire or seizing.
When winding on the drum rope should hang around a wooden mallet.
Apply a metal hammer to avoid damage to galvanizing and subsequent rusting of the cable can not.
In areas of contact with sharp protruding parts, under the rope put wood strips or enclose mats.
During operation, the cables should be regularly lubricated. Lubricant, which has antiseptic and anti-corrosion properties, greatly increases the service life of cables. Good lubrication is cable ointment. Also apply petroleum jelly, grease and synthetic grease lubricant for use zhirovoy.Nelzya ropes fuel oil, diesel fuel, waste oil and other substances containing acid and alkali. Lubricate cables at least once every three months and each time after a stay cable in the water. Before lubricated cables metal brushes remove old ointment and dried mud. Grease is applied a layer of low-fat. If you notice rust cable should be cleaned from it, and lubricate.
Cables with organic cores can not be kept in places with high temperature, since the cores can burn out.
Torn wire is cut short, and the cord in these places okletnevyvayut soft wire. At the end of the cable to avoid unwinding imposed strong wire marks. Disadvantages tether removed immediately, and become unusable cables replaced.
Storage and service life of steel cables.
Steel cables, in use, keep wound tightly in rows naderevannnyekatushki. At least once a year, check their condition and change the grease. Larders should be dry and systematically ventilated.
With proper care the life rope standing rigging is practically unlimited. For cables running rigging, mooring ropes, lifting ropes, he is 4.2 years. Cables for lifting goods and people deemed unfit for use, if the number of broken wires in a length equal to eight diameters of the rope is more than 10% or burst an entire strand.
Excessive tether also harmful. The life of the cables have a significant impact diameter of rollers, blocks or drums, and the state of their surfaces.
