Structure and introduction of laser welded joint
Addtime：2017-09-16 Browse times：2146
The laser processing head is the key component of laser welding equipment, use it to adjust the focal length, the working distance, which can obtain the appropriate spot size in laser welding machine, integrated components with different functions, including laser focusing and import unit, protecting gas import and distribution unit, cooling system and lens protection in the system, with feedback control of laser welding process, but also with the monitoring and feedback control unit. The structure of laser welding nozzle is very complex, which plays an important role in guaranteeing welding quality. Many laser nozzles with different characteristics have been developed both at home and abroad. From the point of view of gas protection, it is necessary to ensure the smooth introduction and uniform distribution and flow of the gas, and ensure uniform coverage of the laser welded zone to form a good protection effect. Generally speaking, the integration design of the coaxial arrangement of the nozzle and the laser beam is the mainstream. Although the structure is complex and the cost is high, the protection effect is good and stable and reliable. The method of introducing the protection gas into front and back is relatively simple, but the protection effect is poor, and has been adopted less. Typically, the distance from the nozzle to the workpiece is at 3mm - 10mm.. The nozzle bore diameter is 4mm -8mm and the gas flow rate is at 8L/min - 30L/min. Figure 3-41 shows the schematic diagram of the laser welded nozzle. Figure 3-42 shows the laser welding nozzle.
CO2 laser welding adopts oxygen protection, so the design requirement of nozzle is higher, so as to ensure good air flow geometry. The basic principle of the design is to ensure high argon flow rate to improve liquid metal inhibition of plasma production. The greater the laser energy density, the greater the argon flow rate. However, excessive argon flow will blow up the weld pool and cause deviation of the weld. Nitrogen has little demand for nozzle structure design and gas flow geometry, but if the laser power density is larger, appropriate measures should be taken to restrain plasma generation.
CO2 laser welding adopts oxygen protection, so the design requirement of nozzle is higher, so as to ensure good air flow geometry. The basic principle of the design is to ensure high argon flow rate to improve liquid metal inhibition of plasma production. The greater the laser energy density, the greater the argon flow rate. However, excessive argon flow will blow up the weld pool and cause deviation of the weld. Nitrogen has little demand for nozzle structure design and gas flow geometry, but if the laser power density is larger, appropriate measures should be taken to restrain plasma generation.