| As the cars request higher and higher corrosion resistance,galvanized sheet is widely used in automotive industry.Welding is very popular in the connection of car galvanized sheet,the normal welding technology are arc brazing,laser brazing,laser welding.etc.These welding technology could provide high welding quality.The application of low heat input arc brazing and laser brazing,Vastly reduce the evaporation of galvanized layer.or in the method of laser welding,control the gap between welding sheets,blow protect gas,add chemical elements,open holes for gas,double laser beam,wave welding,pulse laser welding…etc.to increase the welding quality of galvanized sheet laser welding.Using MAG with ER50-6 Carbon wire weld galvanized sheet is common,but due to the galvanized layer,the temperature of the MAG arc is high,during welding galvanized layer gasify a lot,the temperature of the MAG arc is high,during welding galvanized layer gasify a lot,Effect the stable of arc and cause spatter,the zinc fume which not released,stay in the weld seam become pore,lead to weld defects like pore,poor fusion,spatter.The arc brazing with CuSi wire has better welding form,but the cost of copper wire is high,the strength of weld seam is low.Laser welding as a new welding technology,has the benefit of high light level,good directivity,low heat input.And easy automated,are getting more and more widely used,but the laser weld equipment is expensive,the large one-time investment limited the popularization of laser welding.The MAG welding with carbon wire has low cost,but with normal power source.There's lot spatter and weld defects.With the development of digit inverter power source,the weld data could be checkedand process real time.The dynamic response and control are accurate,could adjust parameter and control waveform according to weld process,it makes welding different kinds of complex material and structure possible.This topic research with Panasonic robotic power source SP-MAG and HD-PULSE welding process.Use carbon wire weld galvanized sheet.Firstly test build up weld on flat sheet,To inspect real time arc characteristics and drop transfer,analyze the reason and process of creating spatter and pore in galvanized sheet welding process Optimize weld parameter to get best weld seam.Based on this,according to the application in automotive industry common used overlap joint,optimize parameter,to get stable welding process,less spatter and weld defects,goods looks weld seam,Provide theoretical foundation and experimental data for galvanized sheet MAG welding process.(1)Weld steel Q235 shows that the two welding process have stable drop transfer due to specific waveform SP-MAG.According to control of short circuit,SP-MAG process could have short circuit transfer which has low heat input,less spatter.HD-PULSE process could have one drop transfer by each pulse,short arc and less spatter.(2)Welding galvanized plate,in proper condition,if the base material not weld rough,the weld still stable.The drop transfer is still short circuit transfer,but the frequency is lower than Q235.But also have less spatter and no pores when welding thin galvanize layer sheet.With back pad and weld through,the Zinc vapor will leak out from welding seam,influence welding.(3)With HD-PULSE process weld galvanize sheet,the drop transfer is disturbed by zinc vapor,need optimize wave and other parameter.With 90%Ar+10%CO2 gas,change separately the welding voltage,pulse peak current,pulse frequency,This will get a stable drop transfer,reduce spatter.The experiment show,adjust this three parameter will have better process parameter and data,reduce spatter and pores.(4)To analyze the factor of difference of each joint type in automotive industry,after Orthogonal test we got a good process parameter.So it is possible to weld thin galvanized steel with MAG welding process,will get high quality welding seam.When weld thick galvanized layer steel,the effect of Zinc is stronger,need to optimize process. |
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