Simulation Of Temperature / Stress Field In Laser Cladding Of Variable Wall Thickness Parts And Research On Process

Variable wall thickness parts are widely used in energy generation,ship transportation and oil drilling and mining industries.The repair of such parts is becoming more and more important.The variable wall thickness parts can be easily affected by temperature during the repair process,affecting the precision of parts usage,and normal repair technology cannot meet the repair requirements.Laser cladding technology has obvious advantages in the field of green remanufacturing and parts repair nowadays.However,there is no uniform standard for the process of laser cladding and changing the thickness parts,and there is no corresponding theoretical basis.It is very difficult to obtain the distribution law of temperature field and stress field during laser cladding of thick-walled parts,and it is difficult to theoretically support the laser cladding process of variable wall thickness parts.This paper selected a copper-based variable wall thickness tube that is sensitive to temperature as a research object,analyzed the laser cladding process of the variable wall thickness part from the theoretical level,and uses ANSYS finite element software to change the thickness of the copper in the variable wall thickness part.The laser cladding temperature and stress fields were simulated and simulated.The laser absorption rate of copper-based variable wall thickness parts was analyzed and studied.In the process of establishing the temperature field model using ANSYS finite element software,a new variable laser absorption was proposed.The laser cladding temperature field of the thin-wall and thick-wall area of the parts is solved by using the finite element model,and the results of the laser cladding temperature field model are analyzed.The corresponding temperature field experiment was designed to verify the laser cladding temperature field model.In the experiment,a new type of fixture was designed for fixed thermocouple's thermode.This paper choose to use a thermocouple to real-time monitor the temperature at which the actual cladding,analyzing and comparing the temperature data obtained in the experiment and the temperature data in the temperature field model.It is concluded that variable wall thickness of brass laser cladding temperature field model is accurate and reliable,the simulation results accord with actual situation.According to the results of the temperature field model,the stress field model of the thick-walled copper tube was established,Referring to the temperature field distribution under the same conditions,.The temperature of cladding layer in the thin-walled region has a great influence on the surrounding area.The molten pool temperature is higher than the thick wall area's molten pool temperature.The local temperature distribution is more uniform than the thick wall area.The stress concentration in the thin-walled area is lower than that in the thick-walled region.The stress average of thin-walled area is smaller than the thick wall area's stress average.However,the increase of temperature causes the material yield limit to fall,and it is prone to deformation.Proposed two kinds of laser cladding process for variable wall thickness copper tube.Studied the influence of laser cladding process on the temperature field.Compared the distribution of laser cladding temperature field of the variable wall thickness copper tube with two different cladding processes.Select the process plan which meets the requirement of laser cladding of variable wall thick copper tube for stress study.In order to show the important influence of the laser cladding process of the variable wall thickness copper tube on the cladding quality,The actual laser cladding is carried out by using the process parameters obtained in the previous research.The cladding process is: First,cladding the thin wall area at each end of the copper tube.Then,continuously cladding The intermediate thick-walled region.Laser cladding process parameters of variable wall thick copper tube are as follows: The preheating temperature is about 300 degrees,laser power 2KW,scanning speed 0.01m/s,the feed rate is 35%.observing the metallography of the copper tube sample after the cladding,found that the cladding layer and the part matrix metallurgy are combined,measured the microhardness.The surface hardness of the parts has been greatly improved.The cladding result of the laser cladding of the variable wall thickness copper tube is consistent with the requirement of cladding,which shows that the laser cladding process of the variable wall thickness has important influence on the cladding quality.