Temperature Field Simulation And Detection Of Asymmetric Fillet Weld Penetration Forming In Medium And Heavy Plates

The asymmetric structure of angle-joint is characterized by special T structure that contains two different plates at thickness.And the structure is widely applied in industrial areas.During the process of welding,asymmetric angle-joint board has two different plates at thickness in order to induce the unbalanced distribution of heat,while using the method that only applies the symmetrical ones is difficult to meet the requirements of welding.Backing welding can prevent angular distortion or burn through automatic welding.In unilateral V groove of plate butt,backing welding is an essential step so that makes its role particularly important.In addition,because the uneven distribution of the heat makes the backing welding is difficult to achieve in the asymmetric angle-joint structure.In order to solve the asymmetric angle-joint structure welding problem about backing welding,this paper proposed by changing the welding-angle to realize the energy distribution,thus obtain good penetration forming.Firstly,this paper used the software COMSOL of finite element analysis and regarded asymmetric in medium plate of angle-joint structure as the research object.The welding temperature field respectively researched the welding penetration of welding-angle of 30,45 and 60.Geometry model about asymmetric structure of fillet welding was established before simulation analysis,and divided the different density of the grid following the actual situation of welding.Choosing the double generalized ellipsoid heat source as moving and welding heat source.The temperature field model was also established,and obtained the distribution of temperature field.By using different welding current and welding-angle of welding methods,molten pool forming rule was analyzed and the welding penetration effect was best in the welding current of 150 and welding-angle of 45.Secondly,testing platform of asymmetric fillet welding was established that based on CCD camera.By it,I obtained the molten pool image of different welding technology,welding current and welding-angle.With image processed,I take advantage of the edge information of the molten pool.First of all,the molten pool form detected under the condition of MIG and TIG welding.The welding processes of molten pool images were analyzed to get the welding environment under the different welding process.I used the molten pool flow situation to analyze the welding quality.Combined with the temperature field simulation,welding graphics were analyzed to verify the theoretical analysis.Finally,I achieved the back of the temperature information of molten pool by using the principle of infrared thermal imager to study the temperature field of the asymmetric angle-joint structure.I also obtained the message to verify the correctness of the numerical simulation.Using uncooled focal plane as the research object,infrared thermal imager measured the welding temperature field of the Q235 steel tungsten argon arc welding,and using numerical simulation method made up for a lack of strong arc interference temperature field in order to achieve the welding temperature field as a whole.With collecting and analyzing the temperature field at different welding technology,different welding current and different welding angle are tested by infrared thermal imager.I achieved the process of heat transfer and surface changing-temperature field of asymmetric structures.I studied about these effects of different conditions on the temperature field of the asymmetric structure.Through images captured.I analyzed different isotherms and molten pool area.Sizes with width information of molten pool can be analyzed from pool area.Therefore,sizes of welding width are compared at different welding-angle.Compared the obtained thermal images to the numerical simulation of temperature field,the correctness of the numerical simulation was verified.