When the two edges of the tube blank are heated to the welding temperature, the common metal grains are formed under the extrusion of the extrusion roll, which permeate and crystallize with each other, and finally form a solid weld. If the extrusion force of the weld is too small, the number of common crystals will be small, the strength of the weld metal will decrease, and the cracking will occur after the force is applied; if the extrusion force is too large, the melted metal will be extruded from the weld, which not only reduces the strength of the weld, but also produces a large number of internal and external burrs, and even causes welding. Defects such as joints. Therefore, attention should be paid to the regulation of the position of the high-frequency induction coil.
The high frequency induction coil should be as close as possible to the weld position of the forged pipe fittings. If the induction coil is far from the extrusion roll, the effective heating time is longer, the heat affected zone is wider, and the weld strength decreases; on the contrary, the weld edge is not heated enough, and the forming is not good after extrusion. The surface impedance of threaded pipe fittings is a special magnet rod or a group of welded pipes. The cross-sectional area of the impedance should not be less than 70% of the cross-sectional area of the inner diameter of the pipe. Its function is to form an electromagnetic induction loop between the induction coil, the edge of the weld seam of the tube blank and the magnet rod, which produces a proximity effect. The edge of the billet is heated to the welding temperature. The impedance device is dragged in the billet with a steel wire, and its center position should be relatively fixed near the center of the extrusion roll. During startup, due to the rapid movement of the tube blank, the impedance is worn down by the friction of the inner wall of the tube blank, so it needs to be replaced frequently. High pressure pipe
After welding and extrusion, the pipe welds will produce scarring and need to be removed. The cleaning method is to fix the tool on the rack and scrape the weld scar by the fast movement of the welded pipe. The burrs inside the welded pipe are not removed because they do not affect the appearance and normal use.
we have our own pipe fitting factory since 1998 ,which covers 100 acres. In 1998, we invested and set up a new flange factory. Up to now, we have a complete production system, and become a professional and competitive group in this field.