Laser cutting is a horizontal laser beam emitted by a laser that passes through a 45° total reflection mirror and becomes a vertically downward laser beam. After being focused by a lens, it is concentrated into a small spot at the focus. When the spot is irradiated on the material, the material is made. It is quickly heated to the vaporization temperature, evaporating to form a hole, and as the beam moves against the material, and the auxiliary gas (carbon dioxide gas, oxygen, nitrogen, etc.) is blown away to melt the waste residue, so that the hole is continuously formed into a narrow width (such as About 0.1 mm) slitting to complete the cutting of the material.
The principle of laser cutting
Laser cutting uses a focused high-power-density laser beam to illuminate the workpiece, causing the irradiated material to rapidly melt, vaporize, ablate, or reach a flash point, while blowing the molten material through a high-speed airflow coaxial with the beam, thereby cutting the workpiece. open. Laser cutting is one of the hot cutting methods. The principle of laser cutting is shown in the figure below.
Laser cutting classification
1) Vaporization cutting
The workpiece is heated by a high energy density laser beam. Vaporizes in a short period of time to form a vapour. A cut is formed in the material. The heat of vaporization of the material is generally large, so large power and power densities 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) Melt cutting
When the laser is melted and cut, the metal material is melted by laser heating, and the nozzle sprays a non-oxidizing gas (argon, helium, N, etc.), and the liquid metal is discharged by the strong pressure of the gas to form a slit. 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) Oxygen cutting
It uses a laser as a preheating heat source, and a gas which is sprayed with a reactive gas such as oxygen as a cutting gas acts, on the one hand, to react with the cutting metal to generate an oxidation reaction, and emits a large amount of heat of oxidation; on the other hand, the molten oxide and the melt are removed from The reaction zone is blown out, and the cutting speed is much greater than laser vaporization cutting and melt cutting.
Laser oxygen cutting is mainly used for easily oxidized metal materials such as carbon steel, titanium steel and heat-treated steel.
4) 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.
Controlled 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 slots.
Laser cutting application range
Most laser cutting machines are controlled by a numerical control program or made into a cutting robot. Laser cutting is a sophisticated machining method that cuts almost all materials, including two-dimensional or three-dimensional cutting of thin metal sheets.
In the field of automobile manufacturing, the cutting technology of space curves such as car roof windows has been widely used. Volkswagen AG uses a 500W laser to cut complex body sheets and various curved parts. In the aerospace industry, aerospace components processed by laser cutting include engine flame tube, titanium alloy thin wall machine, aircraft frame, titanium alloy skin, wing long stern, tail siding, helicopter main rotor, space shuttle ceramics. Heat insulation tiles, etc.
Laser cutting forming technology also has a wide range of applications in non-metallic materials such as silicon nitride, ceramics, quartz, etc.; flexible materials such as cloth, paper, plastic sheets, rubber, etc.