The principle of laser processing of welding head

The principle of laser processing of welding head

Laser head processing technology is a technology for cutting, welding, surface treatment, stamping and micromechanical materials (including metals and non-metals) using the interaction between laser beams and substances. As an advanced manufacturing technology equipment, laser head processing has been widely used in automobile, electronics, electrical appliances, aviation, metallurgy, machinery manufacturing and other industries. It plays an increasingly important role in improving product quality and labor productivity, automation, pollution-free and reducing material consumption.

Welding head laser processing

Laser machining of welded joints is a machining method that uses a focused laser beam as a heat source to bombard the workpiece, melting metal or non-metal workpieces, forming small holes, cuts, connections, cladding, etc. Laser processing is essentially an interactive process. Under the microscope, it is a quantum process. On a macroscopic scale, it is reflected, absorbed, heated, melted and evaporated.

Under the irradiation of laser head beams with different power densities, various changes occurred in the surface area of the material, including surface temperature increase, melting, vaporization, formation of pores and generation of photoplasma.

1. The power density of the laser welding head is less than an order of magnitude

When the power density of the laser head is less than an order of magnitude, the absorption of the laser head energy by the metal only results in an increase in the surface temperature of the material, but the solid phase remains unchanged. Mainly used for surface heat treatment, transformation hardening treatment or partial brazing. When the power density of the laser head is in the order of magnitude, heat conduction type heating is generated, and the surface layer of the material is melted, which is mainly used for surface remelting, alloying, cladding and heat conduction type welding (such as high-speed welding and precision spot welding of plates, etc.).

2. The power density of the laser welding head reaches an order of magnitude

When the power density of the laser welding head reaches an order of magnitude, under the irradiation of the laser head beam, the central heating temperature of the heat source of the laser welding head reaches the boiling point of the metal, forming plasma vapor and strong gasification, and under the action of the gasification expansion pressure, the liquid The surface is concave downward to form deep melting pores; at the same time, the metal vapor is ionized under the action of the laser welding head beam to generate photo-induced plasma. This stage is mainly used for laser beam deep penetration welding, cutting and drilling.

3. The beam power density of the laser welding head is greater than an order of magnitude

When the power density of the laser beam is greater than an order of magnitude, the photoinduced plasma will propagate along the incident direction of the laser beam, forming a plasma cloud, which will lead to the shielding of the laser by the plasma. This stage is only suitable for drilling, impact hardening and other pulsed laser processing.

Technicians in laser welding heads use a high-power-density laser beam to irradiate a workpiece to melt and vaporize material for special processing such as stamping, cutting, and welding. Due to the low power, early laser processing was mainly used for drilling small holes and micro-welding. By the 1970s, with the emergence of high-power carbon dioxide lasers, high repetition rate yttrium aluminum garnet lasers, and in-depth research on the processing mechanism and technology of laser heads, laser welding head processing technology has made great progress, and its application range. also expanded accordingly. The emergence of several kilowatts of laser processing equipment, combined with photoelectric tracking, computer numerical control, industrial welding robots and other technologies, has greatly improved the automation level and use of laser head processing.

Laser head processing equipment consists of four parts, namely laser, optical system, mechanical system, control and detection system. The high-intensity laser beam output by the laser is focused on the workpiece through a lens, and the power density during focusing can reach more than 10,000 degrees Celsius, and any material will melt and evaporate instantly. Laser machining uses the thermal effects of this light energy to weld, stamp and cut materials. The lasers usually used for processing are mainly YAG solid-state lasers and carbon dioxide gas lasers. Because carbon dioxide laser has the advantages of simple structure, large output power range and high energy conversion efficiency, it can be widely used in laser processing of materials.