Forming Process And Application Of Straight Seam Steel Pipe

The straight seam steel pipe is a steel pipe which is parallel with the longitudinal seam and the steel pipe.

　　Usually divided into metric welded steel pipe, welded thin-walled tube, transformer cooling tubing and so on.

　　Production process Straight seam high-frequency welded steel pipe has a relatively simple process, rapid continuous production characteristics, in civil architecture, petrochemical, light industry and other departments have a wide range of uses.

　　It is used for conveying low pressure fluids or making various engineering components and light industrial products.

　　1. Straight seam high frequency welded steel pipe production process Straight Seam welded steel pipe is a certain specification of the steel strip rolled into a round tube through high-frequency welding unit and welded straight seam into a steel pipe. The shape of the steel tube can be round or square or shaped, depending on the sizing and rolling of the weld. Welded steel pipe materials are mainly: low carbon steel and σs≤300n/mm2, σs≤500n/mm2 Low-alloy steel or other steel.

　　The production process of high frequency welding of straight seam steel pipe is as follows:

　　2. High Frequency welding High-frequency welding is based on the principle of electromagnetic induction and alternating charge in the conductor's skin effect, proximity effect and eddy heat effect, so that the weld edge of the steel local heating to the melting state, through the extrusion wheel, so that the butt weld to achieve crystal indirect, so as to achieve the purpose of welding weld.

　　High-frequency welding is a kind of induction welding (or pressure contact welding), it does not need weld filler, no welding spatter, welding heat impact zone narrow, beautiful welding, welding machinery, good performance and so on, so in the production of steel tube by a wide range of applications. High-frequency welding of steel pipe is to use the skin effect of alternating current and neighboring effect, steel (strip) after rolling, forming a cross-section of the broken circular tube billet in the tube near the center of the induction coil rotating A or a group of impedance (magnet), impedance and the opening of the tube to form an electromagnetic induction circuit,

　　Under the action of skin effect and neighboring effect, the edge of the opening of the billet produces a strong and concentrated heat effect, so that the weld edge is heated to the welding temperature by pressing the pressure roll, the molten metal is indirectly combined, and then a solid butt weld is formed after cooling.

　　3. High frequency Welded pipe unit The high frequency welding process of the straight seam steel pipe is completed in the high frequency welded pipe unit. High-frequency welded pipe sets are usually formed by rolling, high-frequency welding, extrusion, cooling, sizing, flying saw cut off components, the front end of the unit is equipped with storage, the rear end of the unit is equipped with steel pipe turnover rack; The electric part mainly has the high frequency generator, the direct current excitation generator and the instrument automatic control device and so on.

　　Now take φ165mm high-frequency welded pipe Unit For example, its main technical parameters are as follows:

　　3.1 Welded pipe finished product

　　Outer diameter of pipe: φ111~165mm

　　Square Tube: 50x50~125x125mm

　　Rectangular tube: 90x50~160x60~180x80mm

　　Finished Taibiho: 2~6mm

　　3.2 Molding Speed: 20~70 m/min

　　3.3 High Frequency sensor:

　　Thermal Power: 600KW

　　Output frequency: 200~250khz

　　Power supply: Three-phase 380V 50Hz

　　Cooling: water-cooled

　　Excitation Voltage: 750~1500v

　　4. High frequency excitation circuit High-frequency excitation circuit (also known as high-frequency oscillation Circuit), is installed in the high-frequency generator in the large tube and oscillating resonators composition, it is to use the amplification of the tube, in the tube when the filament and anode, the anode output signal is fed to the grid, forming a self-excited oscillation circuit.

　　The magnitude of the excitation frequency depends on the electrical parameters (voltage, current, capacitance, and inductance) of the oscillating resonators.