Most items made of stainless steel are anti-corrosive, and items made of stainless steel are also processable. Therefore, stainless steel can be used in different fields, such as the aerospace industry, the medical industry, and different types of mechanical instruments. Industry, stainless steel materials are also widely used in coal mine machinery and facilities, and it is very important to choose the appropriate cutting processing method. It is difficult to guarantee the cutting quality and cutting efficiency when cutting materials with traditional cutting technology, but laser cutting technology It can make up for the shortcomings of traditional cutting technology. Laser cutting technology has the advantages of high speed and high precision. However, the heat emitted by the laser cutting process is small and the incision is narrow. Although laser cutting technology can well make up for traditional cutting technology, it can make up for the shortcomings of traditional cutting technology. There are many existing problems, but there are also many factors that affect the quality of laser cutting. If the selection of processing technology data is inappropriate, the cutting quality will definitely be affected. As laser technology is widely used in the welding process of stainless steel sheets, certain parts need to be cut before the welding operation can be carried out. Currently, there are stricter regulations on the shape and quality of the cut end faces, and it is necessary to laser cut the stainless steel sheets. The appearance and cutting quality were further explored.
1 Principle of laser cutting Laser cutting includes melting cutting and oxidation melting cutting.
Gasification cutting, controlled fracture laser cutting and laser burning cutting. When the high-power laser is focused on the raw material through the lens, it can be injected into the material instantly, causing the material to melt, chemically fracture and evaporate. High-pressure auxiliary gas ejects the evaporated and melted raw materials from the cutting part. This ends the cutting of the material. In laser cutting, each pulse must have sufficient energy and sufficient peak intensity to melt the corresponding volume of material and overcome the loss caused by conduction. Much of the material is ejected as it melts, and only some is eliminated by steam. When the partial evaporation pressure is greater than the cutting gas pressure, it is beneficial to the elimination of material and reduces the thickness of the metal layer in the front section of the incision, thereby optimizing the energy transfer through the molten layer to the solid raw material in front of the incision. Laser cutting technology mainly uses high-power concentrated laser beam to irradiate the parts to be cut. Under the irradiation of larger laser power, the energy emitted by the laser beam and the auxiliary gas help the material absorb the energy released by the laser beam. , causing the temperature of the laser irradiation position to rise, reaching the boiling point and causing the material to be vaporized, causing holes in the material, and finally causing slits in the material, and the slag at the slits is eliminated by the gas. Metal has strong absorption of laser light, so all metals can be laser cut. According to laser cutting theory, laser cutting has the following characteristics: laser cutting processing parts do not need to be in contact with the parts, the cutting gap is narrow, the incision is good, and the processing accuracy is high; the cutting speed is fast, and it has a strong degree of automation.
2 Factors Affecting Laser Cutting Accuracy
2.1 Shape of Laser Beam
Since the shape of laser beam is mainly conical, the gap after cutting the material is also conical. Therefore, the thinner the stainless steel material, the better the gap after cutting. The smaller it is, and the thicker the material, the larger the cutting slit will be, and the lower the cutting accuracy will be.
2.2 Spot size
When the cone-shaped laser beam is focused into one piece through irradiation, the spot will continue to shrink, which will also gradually narrow the cutting gap, thus improving the accuracy of laser cutting. Therefore, the size of the spot affects laser cutting. One of the key factors for accuracy.
2.3 Different material compositions
The cutting accuracy will vary due to different material compositions. For the same material, the local selection of different materials will also affect the cutting accuracy when laser cutting is performed.
2.4 Workbench
Whether it is a simple or high-precision workbench, it will affect the accuracy of laser cutting. For CNC machine tools, since the workbench can move at any time, the movement trajectory of the workbench and the flatness of the workbench will have a certain impact on the accuracy of cutting.
3 Stainless steel laser cutting process optimization and surface quality control measures
3.1 Melting cutting and perforation technology
When a higher energy laser beam is input, when the laser beam irradiates the position of the material to be cut, it will be found that the material begins to evaporate, thus A small hole is formed. When the small hole is surrounded by molten metal, the molten material will be taken away by some auxiliary airflow. For example, for some laser cutting equipment without stamping equipment, there are two main methods of piercing: one is to blast holes. This method of piercing is mainly to use laser to continuously irradiate to create a depression in the middle of the material. pit. And the oxygen coaxial with the laser beam will eliminate the molten material extremely quickly and create a hole. However, the size of the hole is mainly related to the thickness of the plate. When blasting and perforating a thicker plate, the hole diameter will be larger and not round enough. This kind of hole is not suitable for parts with high processing accuracy. Since the oxygen pressure used for piercing is the same as the cutting process, large splashes are prone to occur. The other one is pulse perforation. This perforation technology mainly uses high-power pulse laser to melt or vaporize a small amount of material. Air or nitrogen is usually used as the auxiliary gas.
3.2 Oxidation melting cutting
The focus of oxidation melting cutting method is The laser beam is irradiated onto the raw material to be cut. This cutting method involving oxygen is mainly a chemical reaction. At the same time, this chemical reaction is also an exothermic process. Under the action of heat, small holes appear on the stainless steel material. When the molten metal surrounds the pores, more vapor pores will appear inside the stainless steel. When the oxygen flow rate is higher, the chemical reaction will be more intense, but the speed of eliminating slag will be lower. Faster, however, the flow rate of oxygen is not as fast as possible. If the flow rate of oxygen is too fast, a certain amount of metal oxidation products will be produced at the cutting site, which will easily affect the cutting quality of the material. Therefore, when cutting It is also necessary to control the oxygen flow rate within an appropriate range. The flow rate should not be too fast. If the cooling rate at the slit is fast, it will also affect the cutting quality of the material. During the cutting process of oxidation and melting, laser irradiation is required to generate heat. At the same time, the oxidation reaction is also an exothermic reaction, so oxygen can be used as an auxiliary effect to increase the cutting speed.
3.3 Analysis of the deformation of small holes (small diameter and plate thickness) during cutting.
The choice of cutting method is mainly based on the operating power of the laser cutting machine. For larger power laser cutting machines, the puncture method needs to be changed during material processing. The ordinary puncture method is usually chosen. As for the blasting puncture method, the main characteristics of this method are: It ensures that the surface of the cavity is smooth and not prone to deformation. For laser cutting technology with lower power, in order to ensure the smoothness of the processed materials, it is necessary to choose the pulse type perforation method.
3.4 Surface quality of laser cutting stainless steel
Fiber laser cutting technology mainly uses optical fiber imaging technology to cut materials. Through research on fiber laser technology, it is found that during cutting, the shape and flow properties of the melt film during cutting have an impact on the quality of the cutting, such as causing the cutting edge to be rough or the presence of slag. When using carbon dioxide laser for cutting, it can be found that the interfaces between melt and solid as well as liquid and material are relatively smooth. When using nitrogen to assist cutting, the smoothness of the cut edge may be reduced because the fluidity of the melt is not high enough. By using laser technology to cut AISI316L stainless steel, it can be found that the cutting speed will affect the roughness of the surface. If the cutting speed is small, the width of the heat-affected zone will be increased. When the maximum cutting speed is used to cut stainless steel materials, The roughness is relatively good, and its heat-affected zone range can also be ignored. When using laser technology to cut 316L stainless steel materials, it is necessary to establish the best model suitable for cutting. After using laser cutting technology to cut austenitic stainless steel into thin plate materials, it belongs to fatigue behavior. The research results prove that three types of macro problems will occur during the laser cutting process, mainly including significant bulges on the cutting surface. , unevenness under the cutting edge and the existence of pores at the interface of the cutting material. For some discharged molten materials, scum will appear at the cutting edge. The two cutting technologies of carbon dioxide and fiber optics have significant differences in the process of cutting materials. There will be differences in cutting quality.
4 Conclusion
In the process of cutting stainless steel materials using laser cutting technology, although a large one-time investment is required, the cost of the processing can be greatly reduced during use. The use of laser cutting technology can be widely used in the processing of different types of products, such as cutting crafts with different types of patterns, which can greatly reduce processing time and improve the quality of crafts. When performing laser cutting, experimental optimization technology and modeling analysis are widely used in the research process of optimization solutions. In the subsequent impact research process, the principle of laser cutting still needs to be analyzed, further experimental research on laser cutting of thick plates needs to be carried out, and the thermodynamics and dynamics of materials involved in the laser cutting process need to be modeled and analyzed. , and establish the theoretical basis for laser cutting of materials of different thicknesses and types.
