What are the advantages of using our Joule laser to weld aluminum alloy?

Because Suzhou laser welding aluminum alloy has the following advantages:

1. High energy density, low heat input, small thermal deformation, narrow melting zone and heat affected zone and large melting depth;

2. High cooling rate leads to fine weld microstructure and good joint properties;

3. Compared with the contact welding, the laser welding does not use electrodes, so the man hour and cost are reduced;

4. The vacuum atmosphere of electron beam welding is not needed, and the shielding gas and pressure can be selected. The shape of the workpiece to be welded is not affected by electromagnetic field and does not produce X-ray;

5. It can weld the metal materials inside the sealed transparent object;

6. The laser can be transmitted by optical fiber in a long distance, so that the process has good adaptability. With the help of computer and manipulator, the automation and precision control of welding process can be realized.

There are two basic modes of laser welding in Suzhou: thermal conduction welding and deep penetration welding. The former uses low laser power density (105-106w / cm2). After the workpiece absorbs the laser, only the surface melts, and then the heat is transferred to the workpiece to form a molten pool. This welding mode has shallow depth and small depth width ratio.

The latter has high laser density (106-107w / cm2). After absorbing the laser, the workpiece melts and gasifies rapidly. The molten metal forms a small hole under the action of steam pressure. The laser beam can irradiate the bottom of the hole and make the hole extend continuously until the steam pressure in the hole is balanced with the surface tension and gravity of the liquid metal. When the keyhole moves along the welding direction with the laser beam, the molten metal in front of the keyhole flows around the keyhole to the rear, and the weld is formed after solidification. In this welding mode, the depth of weld is large and the ratio of depth to width is also large. In the field of mechanical manufacturing, in addition to those thin parts, generally should choose deep welding.

The metal vapor and shielding gas produced during deep penetration welding are ionized under the action of laser, thus forming plasma inside and above the keyhole. The plasma can absorb, refract and scatter the laser, so generally speaking, the plasma above the molten pool will weaken the laser energy reaching the workpiece. It also affects the focusing effect of the beam and is not good for welding.

Usually, side blowing can be added to eliminate or weaken the plasma. The formation of keyhole and plasma effect lead to the generation of characteristic sound, light and electric charge in the welding process. It is of great theoretical significance and practical value to study the relationship between them and welding specifications and weld quality, and to use these characteristic signals to monitor the laser welding process and quality.