After the two edges of the large-diameter welded pipe billet are heated to the welding temperature, under the extrusion of the extrusion roller, the single metal grains formed are infiltrated and crystallized with each other to form a strong weld.If the extrusion force is too small, the number of single crystals formed will be small, the strength of the weld metal will decrease, and cracks will occur after being stressed. If the extrusion force is too large, the metal in the molten state will be squeezed out of the weld, which not only increases the strength of the weld, but also produces a small amount of internal and external burrs, and even causes defects such as weld laps. The strip steel is sent to the welded pipe unit, rolled up by multiple rollers, and the strip steel is gradually rolled up to form a circular tube blank with a tooth gap. Adjust the reduction amount of the squeeze roller so that the weld seam gap is controlled at 1~3mm, and the two ends of the weld joint are flush.
The high-frequency induction coil of large-diameter welded pipe should be as close as possible to the position of the extrusion roller. If the induction coil is far away from the extrusion roller, the effective heating time will be longer, the heat-affected zone will be wider, and the strength of the weld will decrease; otherwise, the edge of the weld will be insufficiently heated and the shape will be poor after extrusion. The welding temperature of large-diameter welded pipe is mainly affected by the high-frequency eddy current thermal power. According to the formula, the high-frequency eddy current thermal power is mainly affected by the current frequency, and the eddy current thermal power is proportional to the square of the current excitation frequency. The frequency of current encouragement is affected by the encouragement voltage, current, capacitance and inductance.
What are the design features of large diameter welded pipe
1. The appearance is more beautiful, especially the pipe truss composed of welded pipe members, without redundant node connections, with a strong sense of modernity.
2. The geometric characteristics of the pipe section are good, the pipe wall is generally thin, the section material is distributed around the centroid, the section radius of gyration is large, and it has relatively good torsional rigidity. As a compression, bending and two-way bending member, its bearing capacity is relatively good, and the straightness and cross-sectional dimension of the cold-formed pipe are better than the hot-rolled open cross-section.
3. The welded steel tube is a closed section. In the case of the same average thickness and cross-sectional area, the exposed surface area is about 50% to 60% of the opening cross-section, which is beneficial to corrosion and can save coating materials.
4. From the perspective of anti-hydrodynamic characteristics, the cross-section of the circular pipe is acceptable, and the effect of wind and water flow is greatly reduced. Rectangular tube sections are similar in this respect to other open sections.
5. Concrete can also be poured in the pipe to form a composite member.
Note: LSAW steel pipes and SSAW steel pipes are mostly large-diameter welded pipes
The high-frequency induction coil of large-diameter welded pipe should be as close as possible to the position of the extrusion roller. If the induction coil is far away from the extrusion roller, the effective heating time will be longer, the heat-affected zone will be wider, and the strength of the weld will decrease; otherwise, the edge of the weld will be insufficiently heated and the shape will be poor after extrusion. The welding temperature of large-diameter welded pipe is mainly affected by the high-frequency eddy current thermal power. According to the formula, the high-frequency eddy current thermal power is mainly affected by the current frequency, and the eddy current thermal power is proportional to the square of the current excitation frequency. The frequency of current encouragement is affected by the encouragement voltage, current, capacitance and inductance.
What are the design features of large diameter welded pipe
1. The appearance is more beautiful, especially the pipe truss composed of welded pipe members, without redundant node connections, with a strong sense of modernity.
2. The geometric characteristics of the pipe section are good, the pipe wall is generally thin, the section material is distributed around the centroid, the section radius of gyration is large, and it has relatively good torsional rigidity. As a compression, bending and two-way bending member, its bearing capacity is relatively good, and the straightness and cross-sectional dimension of the cold-formed pipe are better than the hot-rolled open cross-section.
3. The welded steel tube is a closed section. In the case of the same average thickness and cross-sectional area, the exposed surface area is about 50% to 60% of the opening cross-section, which is beneficial to corrosion and can save coating materials.
4. From the perspective of anti-hydrodynamic characteristics, the cross-section of the circular pipe is acceptable, and the effect of wind and water flow is greatly reduced. Rectangular tube sections are similar in this respect to other open sections.
5. Concrete can also be poured in the pipe to form a composite member.
Note: LSAW steel pipes and SSAW steel pipes are mostly large-diameter welded pipes
