Role of skin effect in erw tubes
Also known as the "skin effect," When an alternating current through a conductor, due to induction effect caused by the larger cross section of the conductor current distribution is uneven, the closer the conductor surface current density. The skin effect increases the effective resistance of the conductor. The higher the frequency, the more skin effect is obvious. When a high frequency current through the wire, the current can be considered only in a thin layer on the surface of the wire flows through the wire cross-section which is equivalent to reducing the increase in resistance. Since the central portion is almost no current flows through the wire, this can be a central portion removed to save material. Thus, in the high-frequency circuits can be used instead of solid hollow conductor wire. Furthermore, in order to weaken the skin effect in high-frequency circuits are also often mutually insulated multi-strand braided wire instead of a bundle of the same cross-sectional area of thick wire, which is called multi-strand braided wire harness. In industrial applications, the use of the skin effect can be surface hardened metal.
High-frequency welding of erw tubes use the AC skin effect and proximity effect, steel (steel) after roll forming to form a circular cross section of the tube is disconnected, near the center of rotation of an induction coil in the shell or a group resistor (magnet), the opening of the impedance tube with a magnetic induction loop is formed in the skin effect and proximity effect, the opening edge of the tube to produce a strong and focused heat effect, the edge of the weld rapidly heated to the desired temperature by pressing rollers welded extruded metal in a molten state to achieve indirect co-crystal, forming a firm butt welds after cooling.