Laser means that the laser active material (working substance) is stimulated and emits light, and after the light expands, a light beam with good monochromaticity, strong directionality, and high brightness is attacked. The energy beam with a diameter of less than 0.01mm and a power density of up to 106~l012W/cm2 can be obtained after being collected by a transmission or a mirror and can be used as a heat source for welding, cutting, and data appearance processing.
Laser welding machine is essentially a process of mutual effect between the laser and non-lighting materials, which is a quantum process on the microscopic level, and reflects, absorbs, heats melt, and vaporizes on the microscopic level. During laser welding, the laser beam strikes the surface of the weldment. As part of the attack, one part is reflected and the other part enters the weldment.
The thermal effect of the laser welder depends on the degree of energy absorbed by the weldment, which is often characterized by the absorptivity. Absorption of the laser by metal is mainly related to factors such as laser wavelength, metal properties, temperature, appearance, and laser power density.
Heating of data: Electrons that absorb photons and are at high energy levels will transfer energy in collisions with other electrons and with lattice interactions. The energy of photons eventually translates into the thermal vibrational energy of the crystal lattice, causing data to rise in temperature. High, change data appearance and internal temperature.
Melting and vaporization of data: During laser processing, the conversion of light energy absorbed by the data to thermal energy is completed within a very short time (approximately 10-9 s). In this moment, the heat energy is limited to the laser radiation area of the data, and then it is conducted by heat, and the heat is transferred from the high-temperature area to the low-temperature area.
When the power density is greater than 106 W/cm2, the data to be welded will undergo rapid transpiration.
In a series of laser deep penetration welding, because of the transpiration of the welding data, the vapor pressure and the steam counter effect force can overcome the molten metal surface tension and the static pressure of the liquid metal to form a "hole." The "hole" resembles a "black hole" and contributes to the absorption of light energy.
Wall aggregation effect: When the laser beam enters the small hole because the laser beam is not a parallel beam, it forms a certain incident angle with the whole wall. After the laser beam hits the whole wall, it reaches the bottom of the hole after repeated reflection. It is completely absorbed.
The composition of the weld: the relative motion of the workpiece and the beam, because the external tension of the intense transpiration of the data, the molten metal at the front of the “hole” is accelerated along a certain point of view, and is formed at the rear surface of the “hole” behind the surface. Melt flow. The liquid metal behind the "hole" is a result of heat dissipation. The temperature drops rapidly and condenses to form a continuous weld seam.