Steel wire rope properties
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A general description of the
The steel cable is easy to everyday work practice that is not subject to breaks in the wire pārrīvēšanās, which may lead to quite disastrous consequences, especially when performing responsible work.
By design, the steel wire is a metallic product, which consists of a certain way savītiem vientipa strands (usually six) around the core. The cores tend to be organic (hemp, polypropylene, sīzala, jute) and metal. Each of the six strands, in turn, consists of a certain number of thin stieplītēm with spring properties, which ultimately takes the entire load, as well as provide a tightrope in general the necessary flexibility in execution of lifting operations. The more wire vijumā, because the wire is softer, more flexible and more resilient.
In addition, the steel cables have a number of the most likely performance (twist type and the type of wound and degree of thematic areas equivalent, the calculated values of trūkšanu, etc.).
Steel wire ropes are widely used in various industries, including construction, industry, transport, as well as household and business needs. Braided texture enhances the mechanical strength of metal wires have a low coefficient and low twisting rate. 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 surrounding environment, protecting it from external influences. All this makes the ropes and steel cables suitable to various types of work.
Ropes-use area also affects its structure: it depends on the wire drawing, strength, the recommended load. If we consider the cross section, then the middle is the core – organic or synthetic, around which a certain order is wrapped around the wire from the metallic wire. Inside the strands can also be core. Number of strands around the core and the number of wires in the same vijumā determined by the strength of the cable, the maximum allowable load and izstiepšanu dynamic loading. It, cables with a diameter of not more than 5 mm are used only for extensions, with a diameter of not more than 22 mm – elevators, lifting machinery, ceļamkrānos, with a diameter not greater than 26 mm – for rigging and fixing.
Cinkotās wire is used for cables, spray increasing.
Types of cross cable
Single-lay rope composed of one strand, which has the same diameter wire in a spiral formation in one or several layers (up to four) around one of the wires. The wire and the number of layers of twine are indicated in the ropes raksturojumos with the sum, where the first digit indicates the presence of a central wire, the second the number of wires in the first layer from the center, the third – the second layer, etc.
Double-lay ropes are made, twist several strands in one or two layers around a single metāliskai, organic or mineral core.
Ropes of three strands is stranded without a mandrel.
Rope lay triple twist of several cables. Ropes are made from much finer wire. They are much more flexible, but at the same time, weaker. Are used mainly where in particular need of flexibility, such as light paceļamos mechanisms with a cable wound on the drum tricēm.
Steel cables have the lay of strands right and left direction. In the first case, the wire strands in the cables are twisted in a clockwise direction, but in the second – contrary to anti-clockwise.
By type of lay ropes may be unidirectional, cross orcombi - lay. Unidirectional lay wire ropes wire placed at an angle to the rope axis (б), cross lay wire ropes – parallel to the rope axis (a) compound lay ropes – herringbone (в).
Manufacturers produce cross - (right) lay ropes. They are least susceptible to unwinding does not require special treatment and they are best used on ships. Other species lay ropes are made only at the customer's request.
Ropes with rotational resistance, which during the work negrozās around its axis, is used for rescue, hydrological and other studies.
The steel wire tends to be rigid andflexible. Tight ropes are made from large diameter wires, a small number of with one organic core or without him. They possess great strength. Flexible cables are made from a large number of thin wires and one or more organic cores.
Measurement of wire rope
Steel wire thickness is measured by diameter in millimeters (mm) with vernier callipers. (a – right, б– wrong)
Working with steel wire ropes and their maintenance
Assuming the cable should make a thorough external examination, test design. Cables playback ends they twist the examination, which shall be uniform throughout the length. The cable must not be aprautas, crossed, ielauztas and less strung out on the other wires. The cable wires to the surface should not be dents, cuts and ūsai. The cable must be round entire length. Galvanized wire shall be sturdy, free of cracks. Strands shall not be vājinājumi, the fracture location. Organic cores do not secrete a lubricant and protrude from inside the cable. After the external examination shall take the ropes for measurement and compares the actual design with the data specified in the certificate, for this purpose, easy to unwrap the rope end and transfers the strands number of wires number of strands and the amount of organic cores; checks the coiled placement the strands in the cables and wire placements in the strands. The design of the cable must comply with these data.
Cables must meet the working conditions. The solid line, for example, should not be used as cables, to pass through blocks, as they quickly wear out. Mooring, tugs and lifting equipment equipment used in the flexible cable.
Rope wound around the drum during loading and unloading can not throw, and put a strong blows, the shock of the cylinder, it can kink, but it is difficult to disentangle.
Are not permitted in loop formation, whereas nostiepjot rope, they form a space, which drastically reduces the strength of the cable and makes it useless. The loop should be carefully and properly rewind without pusaizvērtas loop to elongate. Unrolling rituli, the cables unwrap beyond the outer end, while rotating the rituli or cylinder. (a – right, б– wrong)
Prior to the cut off from the rituļa although the steel cable to any length to avoid atritināšanās, the rope imposes on the two brands of soft wire or rope.
Uztinot on the drum rope a wooden mallet.
Use a metal hammer must not, in order to avoid damage to galvanizing and subsequent rust.
In areas of contact with sharp protruding parts, under the rope makes wooden pallets, or remain in the carpet.
During operation, the cables need to be regularly lubricated. Lubricant, which has antiseptic and anti-corrosion properties, significantly increases the service life of cables. Good ziežviela is the rope smēre. Are also used by the technical petroleum jelly, synthetic solidolu and fat solidolu. Not to use the rope for spreading fuel oil, diesel fuel, worked mašīneļļu and other substances containing acid and alkali. Ropes oint not less than once every three months and each time after the wire location in the water. Before lubricated cables with metallic brushes remove old ointment and dried dirt. Polishes are covered with not a whole fatty layer. If you notice rust, the wire needs from its clean up and stain.
Cables with organic cores can not be kept in places with high temperature, whereas the cores can burn out.
Torn wire is cut short crop, but the cord in these places wrap waxed with a soft wire. The rope ends to avoid atritināšanās imposed strong wire marks. Ropes shortcomings disposed of immediately, but discarded cables replaced with new ones.
Steel rope storage and service life
Steel wire ropes, which are used, stored uztītas close rows on the wooden spools. Not less than once a year, check their condition and change the grease. Warehouses must be dry and systematically should be encouraged.
With proper care the life rope standing rigging is practically unlimited. Running rigging, ropes, lifting ropes, he is 2-4 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 significantly affects the roller, block or cylinder diameter and surface condition.