The application of laser cutting

Detailed discussion on the application of laser cutting

1. The cutting seam of laser cutting is narrow and the workpiece deformation is small

the laser beam is focused into a small light spot, which makes the focus reach a high power density. At this time, the heat input by the beam is far more than the part reflected, conducted or diffused by the material, and the material is soon heated to the degree of vaporization, which forms holes. With the relative linear movement of the light beam and the material, the holes continuously form a slit with a very narrow width. The heating effect of trimming is very small, and there is basically no workpiece deformation

auxiliary steam suitable for the material to be cut is also added during the cutting process. When cutting steel, oxygen is used as an auxiliary vapor to produce exothermic chemical reaction with molten metal, oxidize materials, and help blow away the slag in the slit at the same time. Compressed air is used to cut polypropylene and inert vapor is used to cut cotton, paper and other flammable materials. The auxiliary steam entering the nozzle is also 1. The experimental purpose is to cool the focusing lens and prevent soot from entering the lens seat to pollute the lens and cause overheating of the lens

most organic and inorganic materials can be cut by laser. In the metal processing industry, which plays a very important role in the industrial manufacturing system, many metal materials, regardless of their hardness, can be cut without deformation. Of course, for high reflectivity materials, such as gold, silver, copper and aluminum alloys, they are also good heat transfer conductors, so laser cutting is very difficult, or even impossible

laser cutting has no burr, wrinkle and high precision, which is better than plasma cutting. For many mechanical and electrical manufacturing industries, because the modern laser cutting system controlled by microcomputer program can easily cut workpieces of different shapes and sizes, it is often preferred over punching and molding processes; Although its processing speed is still slower than die punching, it has no die consumption, no need to repair the die, and saves the time of replacing the die, thus saving processing costs and reducing production costs, so it is more cost-effective on the whole

2. Laser cutting is a non-contact processing with high energy and good density controllability

after focusing the laser beam, a small action point with extremely strong energy is formed, which has many characteristics when applied to cutting. First, laser light energy is converted into amazing heat energy and kept in a very small area, which can provide (1) narrow straight edge slits; (2) The smallest heat affected zone adjacent to the trimming; (3) Minimal local deformation. Secondly, the laser beam does not exert any force on the workpiece. It is a non-contact cutting tool, which means that (1) check whether the joint of the oil circuit system is tightened) the workpiece has no mechanical deformation; (2) There is no tool wear, and there is no tool conversion problem; (3) Cutting materials do not need to consider its hardness, that is, the laser cutting ability is not affected by the hardness of the material being cut, and any hardness material can be cut. Thirdly, the laser beam has strong controllability, high adaptability and flexibility, so (1) it is convenient to combine with automatic equipment, and it is easy to realize the automation of cutting process; (2) Because there is no restriction on cutting workpiece, the laser beam has unlimited copying cutting ability; (3) Combined with computer, the whole board can be discharged and materials can be saved

3. Laser cutting has extensive adaptability and flexibility

compared with other conventional processing methods, laser cutting has greater adaptability

first of all, compared with other thermal cutting methods, as a thermal cutting process, other methods cannot act on a very small area like a laser beam, resulting in wide incision, large heat affected area and obvious workpiece deformation. Laser can cut nonmetals, while other thermal cutting methods cannot

II. Main process of laser cutting

1. Vaporization cutting

under the heating of high-power density laser beam, the speed of the material surface temperature rising to the boiling point temperature is so fast that it is enough to avoid melting caused by heat conduction, so some materials vaporize into steam and disappear, and some materials are blown away from the bottom of the slit as ejecta by the auxiliary gas flow

2. Melting and cutting

when the power density of the incident laser beam exceeds a certain value, the interior of the material at the beam irradiation point evaporates, forming holes. Once the hole is formed, it will absorb all the incident beam energy as a blackbody. The small hole is surrounded by the molten metal wall, and then the auxiliary air flow coaxial with the light beam takes away the molten material around the hole. As the workpiece moves, the small hole moves horizontally synchronously according to the cutting direction to form a cutting seam. The laser beam continues to irradiate along the front edge of the crack, and the molten material is continuously or Pulsatively blown away from the crack

3. Oxidation melting cutting

melting cutting generally uses inert gas. If oxygen or other active gas is replaced, the material will be ignited under the irradiation of laser beam, and another heat source will be generated by intense chemical reaction with oxygen, which is called oxidation melting cutting

4. Control fracture cutting

for brittle materials that are easy to be damaged by heat, high-speed and controllable cutting through laser beam heating is called controlled fracture cutting. The main content of this cutting process is: the laser beam heats a small area of brittle material, causing a large thermal gradient and serious mechanical deformation in the area, resulting in the formation of cracks in the material. As long as the uniform heating gradient is maintained, the laser beam can guide the crack to produce in any desired direction

III. laser cutting of common engineering materials

1. Laser cutting of metal materials

although almost all metal materials exert the industrial advantages of Ningbo rare earth permanent magnet, Xiaoshan aluminum nickel cobalt magnetic material, Dongyang ferrite permanent magnet and Haining ferrite soft magnetic material at room temperature and have high reflectivity to infrared wave energy, CO2 laser emitting 10.6um beam in far-infrared band is also successfully applied to laser cutting practice of many metals. The initial absorption rate of metal to 10.6um laser beam is only 0.5% - 10%. However, when the focused laser beam with power density more than 106w/cm2 irradiates the metal surface, it can quickly melt the surface in microsecond time. The absorption rate of most metals in molten state rises sharply, which can generally be increased by 60% - 80%

2. Laser cutting of non-metallic materials

10.6um is easily absorbed by non-metallic materials. The poor thermal conductivity and low evaporation temperature make the absorbed beam almost enter the interior of the material. It is still in an important strategic opportunity period of development and vaporizes instantly at the spot irradiation, forming initial holes and entering the virtuous cycle of the cutting process