1. Working principle of laser welding laser
1.1 Working principle of YAG laser
The laser power supply first ignites the pulsed xenon lamp, and discharges the pulsed xenon lamp by the laser power supply to form a light wave of a certain frequency and a certain pulse width. The light wave is radiated to the Nd 3+: YAG laser crystal through the condenser cavity to excite the Nd 3+: YAG The laser crystal emits light, and after resonating through the laser cavity, it emits a pulsed laser with a wavelength of 1064nm. The pulsed laser is expanded, reflected, (or transmitted through an optical fiber) and focused on the object to be welded; on a PLC or industrial PC Under the control of the machine, the CNC worktable is moved to complete the welding. The frequency, pulse width, waveform, table speed and moving direction of the pulse laser required for welding can be controlled by a single chip microcomputer, PLC or industrial PC. The pulse laser can be adjusted and controlled by different settings of the laser frequency and pulse width energy of.
1.2 Working principle of fiber laser
When the pump light passes through the rare earth ions in the optical fiber, it will be absorbed by the rare earth ions. At this time, the electrons of the rare earth atoms that absorb the energy of the photon will be excited to a higher lasing energy level, thereby inverting the number of ions, and the inverted number of ions will be transferred from the high energy level to the ground state in the form of radiation, and release energy Complete stimulated radiation. The laser generated by the fiber laser is output through the fiber and cooperates with the supporting worktable to complete the corresponding welding. Fiber lasers are divided into pulsed fiber lasers and continuous fiber lasers. Among them, the pulse fiber laser can adjust the laser pulse single-point energy by setting the peak power, frequency and pulse width of the laser; the continuous fiber laser can adjust the output laser power by setting the average laser power.
1.3 Working principle of semiconductor laser
Through a certain excitation method, the number of non-equilibrium carrier particles is realized between the energy band of the semiconductor substance (conduction band and valence band), or between the energy band of the semiconductor substance and the energy level of the impurity (acceptor or donor) Inversion, when a large number of electrons in a state of inversion of particles recombine with holes, stimulated emission occurs. The laser generated by the semiconductor laser can also be welded through the fiber output.
2. Features of laser welding
Laser welding is a new type of welding. Laser welding is mainly aimed at the welding of thin-walled materials and precision parts. It can realize spot welding, butt welding, stack welding, sealing welding, etc., and its characteristics are:
It has high aspect ratio, small weld width, small heat affected zone, small deformation, and fast welding speed.
The welding seam is smooth and beautiful, no need to be processed after welding or only simple processing procedures.
The weld seam has high quality and no pores, which can reduce and optimize the impurities of the base metal. The structure can be refined after welding. The strength and toughness of the weld seam are at least equal to or exceed the base metal.
It can be precisely controlled, the focused light spot is small, it can be positioned with high precision, and it is easy to realize automation. Can realize welding between certain dissimilar materials.
3. Weldable materials and industry applications
Laser welding can be applied to the welding of titanium, nickel, tin, zinc, copper, aluminum, chromium, niobium, gold, silver and other metals and their alloys, and the same materials of alloys such as steel and Kovar alloys. It is used for welding of various dissimilar metals such as copper-nickel, nickel-titanium, copper-titanium, titanium-molybdenum, brass-copper, low-carbon steel-copper, etc. At the same time, it is also widely used in mobile phone communications, electronic components, glasses and watches, jewelry, hardware products, precision equipment, medical equipment, auto parts, craft gifts and other industries.
