The process parameters analysis of laser welding machine

1. The power density. Power density is one of the most critical parameters in automatic laser welding machine processing. Use of higher power densities, the time in the microsecond range, the surface layer can be heated to the boiling point, vaporization of a large amount. Therefore, high power density for the material removal machining, such as drilling, cutting, carving. For lower power density, surface temperature reaches the boiling point to go through a few milliseconds, before the vaporization surface, the bottom reaches the melting point, easy to form a good fusion welding. Therefore, conduction laser welding, the power density is in the range of 104 ~ 106W / cm2.
2. The laser pulse waveform. Laser pulse waveform of laser welding is an important issue, especially in the more important for the sheet welding. When the high-intensity laser beam is emitted to the surface, there will be 60 to 98% of the laser reflected energy losing in the metal surface, and the reflectivity of the surface with a temperature change. In a laser pulse period, a large change in reflectivity of the metal.
3. Laser pulse width. Pulse width is one of the important parameters of pulsed laser welding, it is an important parameter different from the material removal and material to melt, but also determine the key parameters automatic laser welding machine cost and volume.
4. Defocus amount on the welding quality. Laser welding generally requires a certain defocus, because the power density of the laser focus spot center is too high, easy to evaporate into the hole. On leaving the laser focus of each plane, the power density distribution is relatively uniform. Defocus two ways: positive and negative defocus. The focal plane is located above the workpiece is positive defocus, and vice versa for negative defocus. Experimental results show that laser heating 50 ~ 200us material begins to melt, forming liquid metal and the emergence of vaporized to form steam, and at very high speed jet, a dazzling white light. At the same time, high concentrations of vapor so that liquid metal moved to the edge of the pool, in the center of the pool formed depression. When the negative defocus, material internal surface area power density is higher, easy to form a stronger melt, vaporize, so that light is transmitted to the deeper material. Therefore, laser welding machines in practical application, when asked penetration is large, the use of negative defocus; welding thin material, to use the positive defocus.