The main heat source uses a high-output semiconductor laser oscillator to control the shape of the laser beam to adapt to the shape of a large rectangular groove, and combines the hot wire method with practical effects in reducing heat energy and improving efficiency to perform a new single-weld vertical welding. Process. The welded portion is surrounded by the same copper plate as the gas shielded arc welding, and the wall of the groove is melted by the laser light reflected on the surface of the molten pool formed by the hot wire method with a large rectangular welded spot suitable for the shape of the groove. The welding process achieves high-quality and high-efficiency welding construction due to low heat energy, low dilution rate, low deformation, etc., and the cost is reduced by reducing the laser power. In addition, it is expected to increase the flexibility of construction in response to changes in the width of the groove. Use a dedicated wire heating power source to heat the filler wire. The wire feed speed of the wire is set corresponding to the groove shape, the welding speed and the wire diameter to form an appropriate weld bead. The wire current is set to the melting point below the temperature at the tip of the wire to avoid melting.

Although the width of the HAZ (heat-affected zone) is widened as the laser output increases, the HAZ is about 8 mm under the condition of a laser output of 5 kW, which is narrower than the HAZ width (15-20 mm) of the conventional arc gas shielded welding. Due to the change in the laser output, the molten state of the groove wall changes, and at the relatively low output, only the outermost surface of the groove melts. Under relatively high output conditions, the groove wall surface is fully melted and the fusion failure rate is also low. On the other hand, changing the welding speed has no large influence on the molten state of the groove wall surface. In other words, the energy density of the laser light that is reflected at the surface of the molten pool and irradiated on the wall surface of the groove has a great influence on the melting of the wall surface of the groove. Longitudinal single bead welding of thick steel sheets with low dilution rate and low heat energy can be achieved by using a welding process combining a large rectangular laser beam and a hot wire method corresponding to the groove size.

The laser welding process is used to set the length of the laser beam corresponding to the thickness of the plate (the length of the groove), and the laser beam is oscillated toward the width of the groove. Even if the width of the groove varies greatly, it is not necessary to greatly increase the laser output, and the same can be formed. The weld pool and the low dilution, low heat welded joint.

Considering the actual situation of the construction site where the laser irradiation is difficult from the top of the groove, the results of the laser oblique projection from the side of the groove indicate that if the irradiation angle is 15°, almost the same result as the illumination above is obtained. In addition, when the single wire method fed from the groove side by the hot wire is basically the same as that of the double wire method, the application to the large-sized member is obtained, and the purpose of welding from one side is realized.

The large rectangular laser welding spot corresponding to the shape of the groove is combined with the hot wire method which can perform the efficient independent feeding control of the filler wire, and can perform the vertical welding of the thick steel plate with low dilution rate and low heat energy; the energy density of the laser The influence of melting on the wall of the groove is large, and the welding speed has little influence on it; by swinging the laser beam in the width direction of the groove, even if the width of the groove is greatly changed, it is not necessary to greatly increase the laser output to form Stable molten pool and good joints; tensile joint tests using joints made by laser welding show that sufficient joint strength can be obtained at the base material.

The use of laser welding technology in the thick steel plate of the ship will bring great progress and great improvement to the quality of the trimming steel. This is because the laser welding uses the I-shaped groove, while the steel mill adopts the disc shear and the bilateral shear edge quality does not meet the groove requirements. The shipyard needs additional beveling to reduce the efficiency and will bring the marine steel plate to cut the revolution of quality.