Will the welding process of straight seam steel pipe be affected during use?

1. Control of weld seam gap: Send the strip steel into the welded pipe unit, roll up the strip steel gradually with roller rolling to form a round tube billet with open gap, adjust the pressure drop of the extrusion roller, so that the weld seam gap is controlled at 1~3mm , both ends of the welding joint are flat, and the gap is too large, thereby reducing the proximity effect. When the eddy current heat is insufficient, the indirect bonding fault of the welding crystal will not melt or break. If the gap is too small, the proximity effect will continue to increase, and the welding If the heat is too large, the weld seam will be damaged, or a deep pit will be formed after the weld seam is squeezed and rolled, which will affect the working quality of the weld seam surface.

2. Welding temperature control: The welding temperature is mainly affected by the high-frequency eddy current heating power. According to the formula, it is found that the high-frequency eddy current heating power is mainly affected by the current frequency, the eddy current heating power and the square of the excitation frequency, and also by the excitation voltage. The frequency is used to realize the capacitive effect of voltage, current and inductance. When the input heat is insufficient, the edge of the heated weld cannot reach the welding temperature, and the metal structure remains solid, forming incomplete melting or incomplete penetration. When the edge of the heated weld is higher than When the welding temperature is high, it will cause overheating or droplet, which will cause the welding seam to form a welding hole.
3. Control of extrusion force: After the two edge welded pipes are heated to a specific temperature, ordinary metal particles penetrate and crystallize in the extrusion of the extrusion roller to form a strong weld. If the extrusion force changes too much, the molten metal It will be squeezed out of the weld seam, which will not only reduce the strength of the weld seam, but also produce a large number of internal and external burrs, which may cause defects such as welding laps. If the extrusion force is too small, the number of crystals that form a common study is small. The strength of the weld metal material will continue to decrease, and cracks will develop after stress analysis.
4. Adjustment of the position of the high-frequency induction coil: The high-frequency induction coil should be as close to the extrusion roller as possible. If the induction coil is far away from the extrusion roller, the effective heating time will be relatively long, the heat-affected zone will be wide, and the weld strength will continue to decrease. On the contrary, The heating technology of the welding edge system is insufficient, and the molding after extrusion is poor. the
5. Impedance is a special magnetic rod for one or a group of welded pipes: the cross-sectional area of the impedance device should generally not be less than 70% of the cross-sectional area of the inner diameter of the steel pipe, and its function is to form an electromagnetic induction loop between the induction rings, and the weld of the rod The edge forms an electromagnetic induction loop, which produces a proximity effect. The eddy current heat is concentrated near the edge of the weld seam of the tube blank, and the edge of the tube blank is heated to the welding temperature. Near the middle of the tight, when starting, due to the rapid movement of the tube blank, the impedance device is greatly affected by the friction of the inner wall of the tube blank, so we need to replace it frequently.