Working principle of laser cutting machine

（1） Laser generation and focusing

The laser generation process in laser cutting machines is complex and exquisite. The laser generator is the core component that generates high-energy, high concentration laser beams through a specific mechanism. Common types of lasers include CO2 laser, fiber laser, and solid-state laser. Taking fiber laser as an example, laser converts electrical energy into light energy. In this process, due to the fact that the conversion between energy cannot be 100%, some electrical energy is converted into light energy while the other is converted into thermal energy. At present, the electro-optical conversion rate of fiber lasers is 25% -35%. The better the performance of the laser, the higher the ratio of electro-optical conversion rate and the corresponding energy consumption.

The generated laser beam needs to be guided and focused through optical devices. Usually, lenses or lenses are used to control the path of a laser beam and focus it into a small diameter spot. For example, two parallel mirrors are placed at both ends of a resonant cavity, with a distance between the mirrors that is an integer multiple of the stimulated radiation wavelength, so that only radiation completely perpendicular to the two mirrors is selected to remain. The radiation in the selected direction continuously proliferates to form a highly coherent laser beam, and the medium molecules that transition to lower energy levels return to higher energy levels under the excitation of external energy, ensuring a continuous supply of excitable medium molecules. The mirror placed at one end of the resonant cavity has a certain transmittance, and the light beam transmitted through the mirror at this end is the laser beam that we can use.

（2） Material processing process

When the focused laser beam is irradiated onto the surface of the material, the material begins to absorb the energy of the laser. Different materials have different absorption rates for laser, and some metal materials have higher absorption rates for laser. The high energy density of lasers enables materials to rapidly heat up to the temperature of melting or vaporization. The melting or vaporization of materials requires a large amount of thermal energy to achieve cutting.

During the cutting process, auxiliary gases such as nitrogen, oxygen, or inert gases are often sprayed through nozzles. These auxiliary gases have multiple functions, one is to cool and prevent material hardening, that is, heat treatment; The second is to blow away the melted metal slag from cutting with air pressure; The third is to assist combustion, such as oxygen cutting, which is beneficial for combustion cutting and will generate more energy. For non-metallic laser cutting machines, blowing one can prevent fire and the other can prevent dust from clogging the laser nozzle. Some special materials also require additional blowing to achieve color retention.

Laser cutting machines are usually equipped with a motion control system to control the movement path of the laser cutting head on the material surface. This can achieve cutting of various complex shapes, controlled by computer programs. For example, in automobile manufacturing, precise motion control systems can be used to cut complex shapes of body components, ensuring accuracy and quality. The process parameters during cutting, such as cutting speed, laser power, gas pressure, and motion trajectory, are controlled by the numerical control system. The slag at the cutting position is blown away by auxiliary gas of a certain pressure.