Research On The Mechanism And Technology Of Laser Cutting With Ten-thousand-watt Power Laser For Thick Carbon Steel

Thick plate carbon steel has good weldability,mechanical properties and machinability,and is mainly used in aerospace,machinery manufacturing,shipbuilding,vehicles,bridge construction and other fields.Its high-efficiency and high-quality cutting can improve the quality of the above-mentioned equipment production and manufacturing.Effectiveness is of great significance.Laser cutting has become the research hotspot of thick plate carbon steel cutting in recent years due to its advantages of narrow slit width,fast cutting speed,high production efficiency,and high degree of automation.Laser cutting uses high energy density to instantly melt the metal sheet and form a slit under the blow-off action of the auxiliary gas.However,in the cutting process of thick carbon steel,due to excessive laser heat input,it is difficult to control the stability of the cutting process,and it is easy to form defects such as thick cut surface stripes and bottom slag,which seriously affects the cutting efficiency and quality,and restricts the laser technology.Application promotion in thick plate cutting.In response to the above problems,this article takes 20mm and 30mm Q345 steel plates as the object to conduct in-depth research on the mechanism and technology of thick plate high-power laser cutting,clarify the key factors that affect the quality and efficiency of thick plate high-power laser cutting,and establish a thick plate Q345 steel high The main contents of the power laser cutting process window are as follows:First of all,the experiment took 20mm and 30mm Q345 steel as the research object,using single factor experiment method to systematically study the influence of each process parameter on the cut surface morphology and cutting quality.For 20mm thick Q345 steel,the laser power is 9000W,the cutting speed is 0.85m/min,the oxygen pressure is1.8bar?2.0bar,the defocus is 12.5mm?15mm,the nozzle diameter is 1.4mm,and the working distance is 0.5mm.When,you can get Class I slitting.A 30mm thick Q345 steel process experiment was used to verify the law of laser cutting thick plates.It was found that if you want to obtain higher cutting quality and faster cutting efficiency,the laser power should be selected as large as possible to ensure the cutting through.Possibly fast cutting speed,larger positive defocusing amount and suitable oxygen pressure and nozzle diameter.Secondly,through the establishment of a molten metal force analysis model,a qualitative analysis of the cutting stripe generation mechanism and morphology was carried out.It was found that the periodic oxygen-iron combustion reaction resulted in the generation of cutting stripes,and the gas pressure in the slit and the temperature of the molten metal caused the stripe to be separated.Layer:Based on the high-speed camera platform,the dynamic behavior of the molten pool is photographed,and the method of removing the molten pool during the cutting process,the causes of slag formation and the causes of the unstable cutting process are explained.Then,through the observation and analysis of metallographic microscope and SEM scanning electron microscope,it is found that the position of the incision can be divided into three regions,the trimming zone,the transition zone,and the base metal zone.Among them,the microstructure in the trimming zone is mainly coarse martensite,the microstructure in the transition zone is mainly granular bainite,and the microstructure in the base material zone is mainly pearlite and ferrite.Finally,the gas flow field model is established by numerical simulation,and the gas velocity and pressure cloud diagram in the flow field in the slit is obtained.It is found that the gas velocity and gas pressure in the flow field in the slit continue downward in the direction of the plate thickness.Decrease,the maximum pressure value of the gas at the top of the slit is about 1.2×10~5Pa,and the maximum velocity value is about 450m/s.