Laser cutting is to use the focused high power density laser beam to irradiate the workpiece, so that the irradiated material can quickly melt, vaporize, ablate or reach the ignition point. At the same time, the molten material can be blown off with the help of the high-speed airflow coaxial with the beam, so as to realize cutting the workpiece. Laser cutting is one of the thermal cutting methods.
Laser cutting can be divided into four categories: laser vaporization cutting, laser melting cutting, laser oxygen cutting and laser scribing and controlled fracture:
1) Laser vaporization cutting
The high energy density laser beam is used to heat the workpiece, so that the temperature rises rapidly and reaches the boiling point of the material in a very short time. The material begins to vaporize and form steam. The steam is ejected at a high speed, and at the same time, a notch is formed on the material. The heat of vaporization of materials is generally very large, so laser vaporization cutting requires a large power and power density.
Laser vaporization cutting is mainly used for cutting extremely thin metal materials and non-metallic materials (such as paper, cloth, wood, plastic and rubber).
2) Laser melting and cutting
During laser melting and cutting, the metal material is melted by laser heating, and then non oxidizing gases (Ar, He, N, etc.) are injected through a nozzle coaxial with the beam of light. The liquid metal is discharged by the strong pressure of the gas to form a notch. Laser melting and cutting does not require complete vaporization of metal, and the required energy is only 1/10 of vaporization cutting.
Laser melting cutting is mainly used for cutting materials or active metals that are not easy to be oxidized, such as stainless steel, titanium, aluminum and their alloys.
3) Laser oxygen cutting
The principle of laser oxygen cutting is similar to that of oxyacetylene cutting. It uses laser as preheating heat source and active gas such as oxygen as cutting gas. On the one hand, the blown gas acts with the cutting metal to produce oxidation reaction, releasing a lot of oxidation heat; On the other hand, the molten oxide and melt are blown out of the reaction zone to form a notch in the metal. The oxidation reaction in the cutting process produces a lot of heat, so the energy required for laser oxygen cutting is only 1/2 of the melting cutting, and the cutting speed is far greater than laser vaporization cutting and melting cutting. Laser oxygen cutting is mainly used for carbon steel, titanium steel, heat treatment steel and other easily oxidized metal materials.
4) Laser scribing and controlled fracture
Laser scribing is to use high energy density laser to scan the surface of the brittle material, so that the material is heated to evaporate a small groove, and then apply a certain pressure, the brittle material will crack along the small groove. The lasers used for laser scribing are generally Q-switched lasers and CO2 lasers.
Controlled fracture is to use the steep temperature distribution produced by laser grooving to generate local thermal stress in brittle materials, so that the materials break along the small groove.
The above is the principle introduction of metal laser cutting machine. Metal laser cutting machine is a kind of automatic typesetting machine, which can save a lot of materials, and the materials cut by metal laser cutting machine are very flat, and its cut is very smooth. The price of metal laser cutting machine is not cheap, but on the whole, it can greatly reduce the manufacturing cost and processing cost of enterprises.