High-frequency welding finned tube
Finned tubes, is to improve the efficiency of heat transfer, usually in the surface of the heat transfer tubes by adding fins, increasing heat transfer tube outer surface area (or internal surface area), so as to improve heat transfer efficiency purposes, such a change heat pipe.
High-frequency welding finned tube
High-frequency welding finned tubes are currently the most widely used one spiral finned tubes, is now widely used in electricity, metallurgy, cement industry, waste heat recovery, and petrochemical industries. High-frequency welding spiral finned tube is wrapped in steel pipe, while the use of high-frequency current skin effect and proximity effect, on the outer surface of the pipe steel and heated until melted plastic state or, in certain pressure wound strip By the completion of welding. Such high-frequency welding solid as a solid phase soldering. Compared with inlay, soldering (or overall hot dip galvanized) and other methods, both in product quality (welded high fin, up to 95%), or on the degree of automation and productivity, are more advanced .
High-frequency welding (high-frequency welding) is a solid resistance heat energy. The use of high-frequency current welding resistance heat generated within the workpiece so that the workpiece surface is heated to melt the weld zone or close to a plastic state, then applied (or not applied) upsetting force to achieve binding metal. So it is a solid-phase resistance welding methods. High-frequency welding, depending on how high-frequency current to generate heat in the workpiece can be divided into contact and induction high-frequency welding high frequency welding. Contact high-frequency welding, high frequency current through the contact with the workpiece mechanical and incoming workpiece. Induction high-frequency welding, the high-frequency current through the coupling piece external induction coil to generate induced currents in the workpiece. High-frequency welding is a highly specialized welding method, according to the product is equipped with special equipment. High productivity, welding speeds of up to 30m / min. Mainly used for longitudinal seam or spiral seam welding pipe manufacturing.
The contents of the two effects of high-frequency welding of high-frequency current is:
Skin effect - when alternating current is passed through the conductor, the conductor section appears uneven current distribution, the current density is gradually increased from the center to the surface of a conductor, most of the current conductor only a physical phenomenon along the surface flow. The lower the resistivity of the conductor, the greater the permeability, the higher the frequency of the current, the skin effect is more significant.
Proximity effect - when the high frequency current in the two conductors in reverse flow back and forth to each other or to flow in a conductor, the current would be concentrated in a specific physical phenomenon conductor near the side flows.
Current frequency range normally used for high-frequency welding 300 ~ 450kHz, sometimes using a low frequency of 10kHz
High-frequency welding finned Features
1, due to welding speed, welding pieces of self-cooling effect, and it is only a small heat-affected zone, but also easy to oxidation, so the organization and properties of the weld is very good.
2, corrosion resistance, wear resistance, low contact resistance, high stability, anti-fouling ability.
3, the heat transfer area is large.
High-frequency welding species
High frequency resistance welding high frequency welding points and two high-frequency induction welding. ① High Frequency Resistance Welding: with the scroll wheel or touching the child as an electrode high-frequency currents in the workpiece, apply a continuous longitudinal seam welded pipe and spiral lap seam welding, boiler tube and fin heat exchanger fin spiral welding, can pipe outside diameter of 1200 mm child, a wall thickness of 16 mm, abdominal beam welding electrode thickness 9.5 mm, high productivity. ② high frequency induction welding: small diameter pipe and wall thickness of the workpiece with the induction heating coil can be welded to an outer diameter of 9 mm and 1 mm thin-walled tube. Commonly used in vertical small diameter steel pipe and brass seam welding, girth welding can also be used, but the power loss is larger than the high-frequency resistance welding. The main parameters affecting the high frequency welding quality is high-frequency power frequency, power, forming the workpiece angle, distance and welding speed extrusion pressure, electrode (or induction coil) and squeeze roll. The main equipment of high-frequency power supply, the workpiece forming apparatus and extrusion machinery. Stable high frequency welding quality, high productivity and low cost. For high-efficiency automatic production line, the production of advanced methods slit tube.