laser cutting

Laser cutting is the most widely used laser processing technology. Its industrial application began in the early 1970s, when it was first used to cut non penetrating grooves on hardwood boards, insert blades, and manufacture molds for punching Paper Cuttings box boards. With the progress of laser devices and processing technology, their application fields are gradually expanding to the cutting of metals such as low-carbon steel and stainless steel, as well as non-metallic plates such as reinforced plastics, ceramics, quartz, and stone, and their application scale is also constantly expanding.

1. Laser cutting mechanism

Laser cutting is the use of a focused high-power density laser beam to irradiate a workpiece. At a certain laser power density, most of the energy of the laser beam is absorbed by the material, causing a sharp increase in the local temperature of the workpiece. After reaching the melting point, the material begins to vaporize and form holes. With the relative movement of the laser beam and the workpiece, the material forms a notch, and the slag at the notch is blown away by a certain auxiliary airflow. According to the different materials and cutting parameters to be cut, laser cutting mainly has the following three methods: vaporization cutting, melting cutting, and reactive melting cutting.

(1) Vaporization cutting

During the vaporization cutting process, the cut material is discharged in the form of steam or residue, which is the basic form of cutting non melting materials such as wood, carbon, and certain plastics.

(2) Melt cutting

This is the basic form of metal sheet cutting. When the cut material is subjected to laser action at a lower power density, it mainly melts rather than vaporizes.

(3) Reaction melting cutting

If inert gas is not used, but oxygen or other reaction gas is used to blow gas, and Exothermic reaction is generated with the cut material, in addition to laser irradiation, energy required for another cutting is also provided.

With the directional movement of the laser beam, a laser beam with high power density can quickly heat up the local area, quickly cutting off ceramic materials and cutting complex parts with arbitrary curve contours.

2 Laser cutting process parameters

The beam characteristics mainly include power, mode, polarization, and stability; The device and processing parameters mainly include the design of the transmission optical path, feed rate, design of the auxiliary gas system, type and pressure of the auxiliary gas, and characteristics related to the material, including thermal physical performance parameters, thickness, density, and basic optical properties. The main influencing factors include laser power, mode, polarization, focal position, cutting speed, auxiliary gas, and the properties of the material itself. The following will analyze these parameters.

(1) Power: The output power of industrial cutting lasers ranges from several hundred watts to several kilowatts.

(2) Mode: The energy distribution of the laser beam profile is called the mode, using TEM mn. Represent. Research has shown that the mode of the laser determines the distribution of beam energy in three-dimensional space. The shape of the beam profile determines the final processing performance. Most laser modes are fundamental or near fundamental, exhibiting a Gaussian or near Gaussian distribution, with small focusing areas and high power density.

(3) Polarization: Like any form of electromagnetic wave transmission, a laser beam has electric and magnetic vectors that are perpendicular to each other and at right angles to the direction of the beam.

(4) Focus position: The focal length affects the diameter and depth of the focal spot. When machining with short focal length, the focal spot diameter is small, the power density is high, the cutting speed is high, the surface roughness is low, and the incision is narrow. However, the focal depth is short, making the incision not straight, and the surface roughness difference between the upper and lower incisions is large. Therefore, it is only suitable for cutting thin materials.

(5) Cutting speed: The productivity of laser cutting is closely related to the cutting speed. The cutting speed determines the time required for laser cutting and the energy that the material can absorb.

(6) Auxiliary gas: Airflow assisted laser cutting of ceramics, laser beam combined with airflow

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