Metal laser cutting machine
First, the principle
Laser cutting uses a focused high-power-density laser beam to illuminate a workpiece, causing the material to be irradiated to rapidly melt, vaporize, ablate, or reach a flash point. At the same time, the molten material is blown off by a high-speed airflow coaxial with the beam, thereby cutting the workpiece. open. Laser cutting is one of the hot cutting methods.
Laser cutting can be divided into four types: laser vaporization cutting, laser melting cutting, laser oxygen cutting, laser scribing and controlled fracture.
1. Laser vaporization cutting
The workpiece is heated by a high energy density laser beam, the temperature rises rapidly, the boiling point of the material is reached in a very short time, and the material begins to vaporize to form a vapour. These vapours are ejected at a high speed, and a slit is formed in the material while the vapour is ejected. The heat of vaporization of the material is generally large, so a large power and power density are required for laser vaporization cutting.
Laser vaporization cutting is often used for cutting very thin metal and non-metallic materials such as paper, cloth, wood, plastics and rubber.
2. Laser melting cutting
When the laser is melted and cut, the metal material is melted by laser heating, and then a non-oxidizing gas (Ar, He, N, etc.) is blown through a nozzle coaxial with the light beam, and the liquid metal is discharged by a strong pressure of the gas to form a slit. Laser melt cutting does not require complete vaporization of the metal, and the required energy is only 1/10 of the vaporization cut.
Laser melt cutting is mainly used for the cutting of some non-oxidizable materials or active metals, such as stainless steel, titanium, aluminium and their alloys.
3. Laser oxygen cutting
The principle of laser oxygen cutting is similar to oxyacetylene cutting. It uses a laser as a preheating heat source and uses an active gas such as oxygen as a cutting gas. On the one hand, the injected gas acts on the cutting metal to cause an oxidation reaction to release a large amount of heat of oxidation; on the other hand, the molten oxide and the melt are blown out from the reaction zone to form a slit in the metal. Since the oxidation reaction during the cutting process generates a large amount of heat, the energy required for laser oxygen cutting is only 1/2 of that of the melt cutting, and the cutting speed is much larger than the laser vaporization cutting and the melting cutting. Laser oxygen cutting is mainly used for easily oxidized metal materials such as carbon steel, titanium steel and heat-treated steel.
4. Laser dicing and control fracture
Laser dicing is to scan the surface of the brittle material with a high energy density laser so that the material is evaporated to a small groove by heat, and then a certain pressure is applied, and the brittle material is cracked along the small groove. Lasers for laser scribing are generally Q-switched lasers and CO2 lasers.
Controlling the fracture is a steep temperature distribution created by laser engraving, creating local thermal stresses in the brittle material that cause the material to break along the small grooves.