Traditional aluminum alloy welding technology can generally be used TIG welding or MIG welding process, but the main research problem faced is that the welding development process there is a large heat input to make the aluminum alloy plate deformation is large, the welding speed is slow, and the production management efficiency is low. Due to the large welding deformation, the subsequent correction work often wastes a lot of time, increasing the manufacturing cost, affecting the efficiency of agricultural production and management and manufacturing product quality.battery pilot line The laser welding has different power density, low welding heat input, welding heat-affected zone is small and welding deformation is small and other characteristics, so that it in the field of aluminum alloy welding continues to receive extra attention.

The main difficulties of aluminum alloy laser welding are.

Due to the high initial reflectivity and thermal conductivity of aluminum alloy, the laser absorption of aluminum alloy before melting is very low.

Aluminum's ionization energy is low, welding plasma is easy to overheat expansion,laser welding machine for lithium ion batteries welding stability is poor.

Aluminum alloy laser welding work process porosity problem.

The mechanical properties of aluminum alloy welded joints decrease with the loss of alloying elements during the welding process.

Solve the problem of aluminum alloy laser welding.

Aiming at the high reflectivity of aluminum alloy to laser light, a lot of research has been carried out at home and abroad.ESS lithium battery machine Test results show that appropriate surface pretreatment, such as sandblasting, sandpaper grinding, surface chemical etching, surface plating, graphite coating and air furnace oxidation, can reduce beam reflection and effectively increase the absorption of beam energy by aluminum alloy. In addition, considering the design of the welding structure, artificial drilling on the surface of the aluminum alloy and jointing in the form of light collector, V-bevel cutting or splicing welding (the joint gap is equivalent to the artificial drilling) can increase the absorption of the laser on the aluminum alloy and obtain greater penetration. In addition, reasonable design of the welding gap can increase the absorption of laser energy on the surface of aluminum alloy.

Due to the high reflectivity and high thermal conductivity of aluminum alloys, it is necessary for the laser to have a higher energy density to induce the formation of pores. Because the energy density threshold is inherently controlled by its alloy composition, a stable welding process can be achieved by controlling the process parameters as well as selecting and determining the laser power to ensure proper heat input. In addition, the energy density threshold is also influenced to some extent by the type of shielding gas. For example, laser welding of aluminum alloys tends to induce pinholes when N2 gas is used, whereas pinholes cannot be induced when He gas is used. This is because an exothermic reaction occurs between N2 and Al, and the resulting Al-N-O ternary compound improves laser absorption.

Crack development problems, aluminum alloy material belongs to a typical eutectic alloy, in laser welding technology rapid solidification conditions are more likely to produce thermal cracks. Weld metal crystallization in the columnar crystal boundary gradually formed Al-Si or Mg-Si and other low melting point eutectic is led to the emergence of cracks can be produced by the main analytical reasons.

In order to reduce the generation of thermal cracks, can be used to fill the wire or pre-positioned alloy powder method of laser welding. When using a YAG laser, crystal cracks can be minimized by adjusting the pulse waveform and controlling the heat input.

Porosity caused by collapse of small holes. During laser welding, when the surface tension is greater than the vapor pressure, the pinholes become unstable and collapse, and the metal forms voids that cannot be filled. Practical measures to reduce or avoid aluminum alloy laser welding porosity defects are also many, such as adjusting the laser power waveform, reducing the instability of the pinhole collapse, changing the focusing height of the beam and tilting the irradiation, applying an electromagnetic field during welding, vacuum welding and so on. In recent years, the emergence of filler wire or pre-positioned alloy powder technology, composite heat source and double focusing technology to reduce the generation of porosity, with good results.

The most attractive feature of aluminum laser welding is its high efficiency, and to make full use of this high efficiency is to apply it to deep-melt welding of large thickness. Therefore, the research and application of high-power laser deep fusion welding of large thickness will be the inevitable trend of future development.