PVC Wires

Reducing power losses in line due to a decrease of more than three times the reactance of isolated wires in comparison with non-isolated. 6. Hear other arguments on the topic with MetLife. Ease of installation work, the ability to connect new subscribers under stress, without shutting down the rest of the energy supply and as a consequence of shortening the repair and installation. 7. Significant reduction of unauthorized access to lines and cases of vandalism and theft.

8. Improving the overall aesthetics of urban environments and a significant reduction in cases of electric shock during installation, repair and operating line. 9. Possibility of laying on the facades of buildings CIP, as well as collaboration with the suspension cables of low, high-voltage lines of communication, which gives substantial savings on support. Among the many undoubted CIP can provide benefits for objectivity and some disadvantages: 1. A slight increase in cost (less than 1.2) insulated wires compared to conventional bare wires A and AS. The pioneers in the application of self-supporting insulated wires is considered to be France and Finland. Subsequently, other countries have developed their air suspension systems, but is usually taken as the basis of their already approved in the operation of the European standards.

In France, the first bundles of insulated wires overhead appeared in 1955 and was a copper conductor with rubber insulation with neoprene jacket. At first, they mounted on the facades of buildings, replacing the bare copper wire on insulators. In 1962, as isolation began to apply the PVC, which by 1977 had completely supplanted by light-stabilized polyethylene mesh structure.

Classification Of Rolling Processes

The rolling process to roll forming equipment manifold. They can be classified according to various criteria. Longitudinal, transverse and oblique (helical) is determined by the location of the axes of vzimnomu machined body and rolls. If the axis of the rolled strip is perpendicular to the axis of the rolls, the rolling is called longitudinal. In the method of rolling strip takm pereseschaetsya only forward, ie performs only translational motion. Longitudinal rolling is the most common.

For the transverse axis rolling obratyvaemogo body parallel to the rolls. Axis of the rolls rotate in one and the same storoonu. They gradually approach each other, resulting in a reduced diameter of the product, which is also rotated, but in the opposite rotation of the rollers. In the longitudinal direction of the processed body does not move (unless otherwise pulling devices). Side rollers perform an auxiliary function: they keep the product between the rollers. Cross-rolling is used in metallurgy and mechanical engineering for the production of axles, shafts, bushings, gears and other products such as bodies of revolution. Oblique rolling, also known as helical, occupies an intermediate position between the transverse and longitudinal. In this case, the axis of the rolls at an angle to each other and to the axis of the rolled round billets.

Through this arrangement the rolls in the process of harvesting rolling does not only rotational but also translational motion. Since the roll angle to the axis of the treated body is usually small (up to 12-18 degrees), oblique rolling in character closer to the transverse than longitudinal. Process skew rolling Shirikov used in the manufacture of seamless tubes, in particular the piercing mill, where a solid round billets are rough pipe – a sleeve. A special type of rolling is so called periodic rolling. It is characterized by Temo in the process of deformation of the gap height varies periodically. Most often this is achieved by giving the special rolls are not round. In this way, get Periodic profiles of rolled shape of the section which varies periodically along the length of the strip. If you change the compression is changing all the parameters of rolling, so periodic rolling can be described as non-stationary (in the transitional areas). Further, the rolling process is divided into symmetrical and asymmetrical. Symmetric rolling call such a process in which the impact of each of the rolls processed in the body is exactly the same, identical. If this condition is violated, then called asymmetric rolling. Among the asymmetric processes are: rolling in rolls of unequal diameter, rolling one drive roller, rolling at different speeds, the district rolls, rolling in the uneven (asymmetric) distribution of the mechanical properties of the height polochy, rolling under different conditions of friction on the rollers, etc. The important condition rolling process is the presence or absence of external forces applied to the ends of the strip. On this basis distinguish between free and unfree rolling. Called free rolling when the lane forces act only from the rolls. Non-free rolling is carried out with the tension or backwater all stripes. Tension force or props are adjacent rolling stands, Coiler-tensioning drums or other devices.


Jigsaw – one of the most popular tools, which is appreciated by professionals and DIY for his versatile. In this article I will tell you the features and talk about the Jigsaw main selection criteria. Jigsaw (Jigsaw electric saw) – Hand tool with an electric drive, which has small dimensions and light weight. Jigsaw is designed for longitudinal, transverse and Shape cutting of various sheet materials. Jigsaw can perform the following tasks: straight cuts virtually any material (wood, sheet metal, plastic, laminate, drywall, ceramic tile, etc.), the curvilinear cut any material to make round holes of various diameters and rectangular openings. Benefits of Jigsaw for most repairs, carpentry and other similar work at home do not need to drink a large capacity, this work perfectly cope electrofret, Jigsaw can make high-quality curly cut material, working with different kinds of materials; indispensable tool for carving; professionals say Jigsaw versatility and ease of use. Jigsaw are professional and household: The household models have less power, working resource and, often, a smaller set of additional features. Jigsaw everyday you can usually cut wooden parts of a thickness of 70 mm, steel – up to 2-4 mm.

Requirements for household tool is not so high as to professional, so many well-known brands make this instrument is not in Germany and Czechoslovakia, as in China or Poland. Recommended total time of use of household is about Jigsaws twenty hours per month. Of course, domestic models have a lower cost than professional. For the professional tool imposed higher requirements, because it must withstand a heavy load, have performance and to be as convenient for work.