A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. I...A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-beat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.展开更多
The plasma-MIG welding torch was developed.5A06 aluminum alloys with V-grooves were welded in a single pass in the plasma-MIG welding process and the joints were examined by X-ray diffractometry analysis and mechanica...The plasma-MIG welding torch was developed.5A06 aluminum alloys with V-grooves were welded in a single pass in the plasma-MIG welding process and the joints were examined by X-ray diffractometry analysis and mechanical tests.The orthogonal experimental design was used to study the influence of plasma-MIG welding parameters on the aluminum weld porosity.The mixed orthogonal matrix L16(4 4×2 3) and analysis of variance (ANOVA)technique were employed to optimize the welding parameters.The experimental results indicate that the effect of plasma gas flow rate is dominant,the secondary factors are MIG welding voltage,welding speed,wire feed rate and plasma current in turn.Confirmation experiments were conducted under optimum conditions and there was almost no porosity in the welded joints,thus good mechanical performance joints were obtained.展开更多
The welding fume has significant effects on the weld workers＇ health. In order to overwhelm the shortcomings of the control measures of the welding fume, the research of the purifying of welding fume on the spot was ...The welding fume has significant effects on the weld workers＇ health. In order to overwhelm the shortcomings of the control measures of the welding fume, the research of the purifying of welding fume on the spot was carried out. The purifying device was designed. The relationship between the corona discharge voltage and the purifying efficiency was investigated through experiments with different needle electrode numbers, different ring electrode numbers and different needle-plate distances. The results show that 5-needle double-ring electrode has the best efficiency; the purifying efficiency is increase with the lessening of the needle-plate distance and the increase of the discharge voltage. Using 5-needle double-ring electrode, the purifying efficiency reaches its maximum value 97.9% while the needle-plate distance is 6 cm, the discharge voltage is -35 kV. The purifying device has an excellent purifying effect on the welding fume.展开更多
文摘A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-beat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.
文摘The plasma-MIG welding torch was developed.5A06 aluminum alloys with V-grooves were welded in a single pass in the plasma-MIG welding process and the joints were examined by X-ray diffractometry analysis and mechanical tests.The orthogonal experimental design was used to study the influence of plasma-MIG welding parameters on the aluminum weld porosity.The mixed orthogonal matrix L16(4 4×2 3) and analysis of variance (ANOVA)technique were employed to optimize the welding parameters.The experimental results indicate that the effect of plasma gas flow rate is dominant,the secondary factors are MIG welding voltage,welding speed,wire feed rate and plasma current in turn.Confirmation experiments were conducted under optimum conditions and there was almost no porosity in the welded joints,thus good mechanical performance joints were obtained.
文摘The welding fume has significant effects on the weld workers＇ health. In order to overwhelm the shortcomings of the control measures of the welding fume, the research of the purifying of welding fume on the spot was carried out. The purifying device was designed. The relationship between the corona discharge voltage and the purifying efficiency was investigated through experiments with different needle electrode numbers, different ring electrode numbers and different needle-plate distances. The results show that 5-needle double-ring electrode has the best efficiency; the purifying efficiency is increase with the lessening of the needle-plate distance and the increase of the discharge voltage. Using 5-needle double-ring electrode, the purifying efficiency reaches its maximum value 97.9% while the needle-plate distance is 6 cm, the discharge voltage is -35 kV. The purifying device has an excellent purifying effect on the welding fume.
