Laser welding is a process that uses the radiant energy of the laser to achieve effective welding. Its working principle is to excite the laser active medium (such as a mixture of CO2 and other gases, YAG yttrium aluminum garnet crystals, etc.) in a specific way. It oscillates back and forth in the resonant cavity to form a stimulated radiation beam. When the beam contacts the workpiece, its energy is absorbed by the workpiece, and welding can be carried out when the temperature reaches the melting point of the material.
Laser welding can be divided into heat conduction welding and deep penetration welding. The heat of the former diffuses into the workpiece through heat transfer, and only melts on the surface of the weld. The interior of the workpiece is not completely penetrated, and there is basically no vaporization phenomenon. It is mostly used for low-speed thin-walled. Welding of materials; the latter not only completely penetrates the material, but also vaporizes the material to form a large amount of plasma. Due to the large heat, a keyhole phenomenon will appear at the front of the molten pool. Deep penetration welding can completely penetrate the workpiece, and has large input energy and fast welding speed. It is currently the most widely used laser welding mode.
Advantages of laser welding
- ① The use of laser welding can obtain high-quality joint strength and larger aspect ratio, and the welding speed is relatively fast.
- ② Since laser welding does not require a vacuum environment, remote control and automated production can be realized through lenses and optical fibers.
- ③ The laser has a large power density, has a good welding effect on difficult-to-weld materials such as titanium, quartz, etc., and can weld materials with different properties.
- ④ Micro welding is possible. After the laser beam is focused, a small spot can be obtained, and it can be accurately positioned, which can be used in the assembly welding of micro and small workpieces that are automatically produced in large quantities.
Disadvantages of laser welding
- ① The price of the laser and the parts of the welding system is relatively expensive, so the initial investment and maintenance costs are higher than the traditional welding process, and the economic benefits are poor.
- ② Because the solid material has a low absorption rate of laser, especially after plasma (plasma has an absorption effect on laser), the conversion efficiency of laser welding is generally low (usually 5% to 30%).
- ③ Due to the small focus spot of laser welding, the equipment precision requirements of the workpiece joint are relatively high, and small equipment deviations will produce large processing errors.
Is laser welding harmful to people?
The invisibility and energy of the laser emitted by the welding machine is too high. Non-professionals should not touch the laser source, otherwise it will be very dangerous. In addition, lasers are also electromagnetic waves, but the wavelengths of lasers used in welding machines are very large, so there is no radiation hazard from short-wavelength light waves such as ultraviolet rays.
Many gases are generated during the welding process, but most of them are inert gases, which are not toxic. However, it depends on the different welding materials. It is best to take protective measures to reduce gas inhalation.
The laser emitted by the welding machine has almost no radiation hazard, but there will be ionizing radiation and stimulated radiation during the welding process. It is best to stay away from the welding part during the welding process. This kind of induced radiation has no shortage of shortwaves, and it has a great impact on the eyes and body. It is best to stay away from the solder joints. Try to take protective measures for close work, such as wearing respiratory protective equipment, wearing radiation protective clothing, and wearing goggles.
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