CO_2激光-TIG复合焊接工艺与机理研究
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摘要
激光—电弧复合焊接是一种新兴的焊接技术,它将激光与电弧两种截然不同的热源复合在一起,同时作用于同一零件的待焊位置,既发挥了两种热源的优势,又弥补了各自的不足,成为了一种全新高效的焊接方法。
本文在总结国内外激光—电弧复合热源焊接研究现状基础上,对CO_2激光—TIG(Tungsten inert gas)复合焊接技术进行了工艺研究。所采用的激光器为Rofin Sinar 5kW快轴流CO_2激光器,电弧焊机为Miller TIG焊机,建立了CO_2激光—TIG电弧旁轴复合焊接系统,在此基础上以3mm厚316L不锈钢板为焊接对象进行了堆焊试验,用显微镜对焊缝的横断面几何形貌进行了测定,结果表明:CO_2激光—TIG复合焊接技术比单独激光焊接和电弧焊接接头的熔深更深、熔宽更大,焊缝成型更美观,接头的焊接质量更好。
本文系统研究了激光功率、电弧电流、热源间距等工艺参数对焊缝成形的影响规律。结果表明:在一定的焊接工艺条件下,激光功率主要影响焊缝熔深,而电弧能量主要影响熔宽。在激光功率大于2.5 kW时,会产生小孔效应,其对复合焊接熔深影响显著;而当电弧电流小于150A时,焊接熔宽与两热源的热输入关系密切,当电流大于150A时,仅电弧电流是焊接熔宽的决定性因素;两热源间距存在一个最佳值2—3mm,此时,焊接熔深可提高1.46—2.54倍。这一结论表明,CO_2激光—TIG复合焊接技术容易获得比较理想的焊接接头。
在以上研究的基础上,本文进一步系统地研究了保护气体组分及其保护方式对CO_2激光-TIG电弧复合焊接工艺稳定性之间的关系。结合所拍摄的焊接过程等离子体图片和焊缝形貌特征及其熔深、熔宽数据,分析了激光与电弧等离子体之间的作用机理。结果表明:在有同轴气体保护下,其能压缩等离子体,增大焊接熔深,而没有该气体时,电弧处于膨胀状态,其吸收和屏蔽激光能量,容易产生电弧畸变的不稳定复合。并据此理论得到了以下结论:只有在合理的气体保护方式下激光与电弧才能取得增强的焊接结果,其中气体保护方式对激光和电弧等离子体相互作用程度的影响是决定两者能否有效耦合的关键因素。单独TIG焊炬保护不能保证激光和电弧的有效耦合,TIG焊炬加旁轴喷嘴的方式只能在较窄的参数范围内获得有效耦合,而TIG焊炬加同轴喷嘴的保护方式则在较宽的范围内都能保证两种热源的有效耦合。
Laser-arc hybrid welding is a new welding technology, which combines the heating sources of both laser beam and the arc on the same molten pool synchronously. The hybrid welding technique holds the advantages of the laser beam and electric arc, which makes it become a new efficiency welding technique.
Based on summarization of the current research on hybrid welding technique, some systematic experimental work was undertaken to study the effect of the hybrid laser–TIG welding process on the bead quality in this paper. Firstly, a paraxial CO_2laser–TIG hybrid welding system was set up by Rofin Sinar 5kW CO_2 laser and Miller TIG welding machine, and a series of bead–on–plate experiments were carried out on the 316L stainless steel sheets with 3mm thickness. The welding bead shapes were characterized by microscope. The experimental results demonstrated that the laser–TIG hybrid welding can increase penetration & width and improve the quality of weld bead formation when the optimum processing parameters were chosen.
The effects of various processing parameters such as laser power, arc current and the distance between the laser beam spot and electric arc spot on the welding shape were studied in detail. It was found that under stated conditions the weld penetration depth mainly depends upon the laser power and the bead width mainly depends upon the arc power. When the laser power is above 2.5kW, there will generate a“key hole”effect in 316L plates, which will enhance the effect of the hybrid heating sources and affect the weld penetration depth greatly;On the other hand, the bead width is closely relative to laser power and the electric arc energy when the arc current is less than 150A. when the arc current is more than 150A, however, the bead width is determined by the energy of the arc only. There exists an optimal laser-arc distance (2--3mm), with which the weld bead penetration depths can be improved to 1.46--2.54 times.
Based on the research results above mentioned,the relationship between the gas concentration & shielding method and the process stability of CO_2 laser-TIG (Tungsten inert gas) hybrid welding is studied in detail. In this paper, the interaction of laser beam with electric arc was studied by the plasma images,the optical photos of the cross-sectional and the bead penetration depths & widths. The results show that the gas of coaxial nozzle can compress the plasma, which increase the welding penetration depths effectively. Otherwise the expanded plasma will absorb too much laser energy and result in unstable hybrid process with distorted electric arc.
Finally, following conclusions can be drawn up from above experimental results: the welding penetration depth can only be enhanced under the appropriate shielding gas method, and the effect of shielding gas methods on the interaction extent between laser plasma and arc plasma is the main factor for efficient synergetic effect. The pure torch method can not generate the efficient synergetic effects, and the hybrid protecting method by torch plus paraxial nozzle method has only a narrow parameter range for getting the efficient synergetic effects, while the hybrid protecting method by torch plus coaxial nozzle method can ensure the efficient synergetic effects under a considerable wide parameter range.
本文在总结国内外激光—电弧复合热源焊接研究现状基础上,对CO_2激光—TIG(Tungsten inert gas)复合焊接技术进行了工艺研究。所采用的激光器为Rofin Sinar 5kW快轴流CO_2激光器,电弧焊机为Miller TIG焊机,建立了CO_2激光—TIG电弧旁轴复合焊接系统,在此基础上以3mm厚316L不锈钢板为焊接对象进行了堆焊试验,用显微镜对焊缝的横断面几何形貌进行了测定,结果表明:CO_2激光—TIG复合焊接技术比单独激光焊接和电弧焊接接头的熔深更深、熔宽更大,焊缝成型更美观,接头的焊接质量更好。
本文系统研究了激光功率、电弧电流、热源间距等工艺参数对焊缝成形的影响规律。结果表明:在一定的焊接工艺条件下,激光功率主要影响焊缝熔深,而电弧能量主要影响熔宽。在激光功率大于2.5 kW时,会产生小孔效应,其对复合焊接熔深影响显著;而当电弧电流小于150A时,焊接熔宽与两热源的热输入关系密切,当电流大于150A时,仅电弧电流是焊接熔宽的决定性因素;两热源间距存在一个最佳值2—3mm,此时,焊接熔深可提高1.46—2.54倍。这一结论表明,CO_2激光—TIG复合焊接技术容易获得比较理想的焊接接头。
在以上研究的基础上,本文进一步系统地研究了保护气体组分及其保护方式对CO_2激光-TIG电弧复合焊接工艺稳定性之间的关系。结合所拍摄的焊接过程等离子体图片和焊缝形貌特征及其熔深、熔宽数据,分析了激光与电弧等离子体之间的作用机理。结果表明:在有同轴气体保护下,其能压缩等离子体,增大焊接熔深,而没有该气体时,电弧处于膨胀状态,其吸收和屏蔽激光能量,容易产生电弧畸变的不稳定复合。并据此理论得到了以下结论:只有在合理的气体保护方式下激光与电弧才能取得增强的焊接结果,其中气体保护方式对激光和电弧等离子体相互作用程度的影响是决定两者能否有效耦合的关键因素。单独TIG焊炬保护不能保证激光和电弧的有效耦合,TIG焊炬加旁轴喷嘴的方式只能在较窄的参数范围内获得有效耦合,而TIG焊炬加同轴喷嘴的保护方式则在较宽的范围内都能保证两种热源的有效耦合。
Laser-arc hybrid welding is a new welding technology, which combines the heating sources of both laser beam and the arc on the same molten pool synchronously. The hybrid welding technique holds the advantages of the laser beam and electric arc, which makes it become a new efficiency welding technique.
Based on summarization of the current research on hybrid welding technique, some systematic experimental work was undertaken to study the effect of the hybrid laser–TIG welding process on the bead quality in this paper. Firstly, a paraxial CO_2laser–TIG hybrid welding system was set up by Rofin Sinar 5kW CO_2 laser and Miller TIG welding machine, and a series of bead–on–plate experiments were carried out on the 316L stainless steel sheets with 3mm thickness. The welding bead shapes were characterized by microscope. The experimental results demonstrated that the laser–TIG hybrid welding can increase penetration & width and improve the quality of weld bead formation when the optimum processing parameters were chosen.
The effects of various processing parameters such as laser power, arc current and the distance between the laser beam spot and electric arc spot on the welding shape were studied in detail. It was found that under stated conditions the weld penetration depth mainly depends upon the laser power and the bead width mainly depends upon the arc power. When the laser power is above 2.5kW, there will generate a“key hole”effect in 316L plates, which will enhance the effect of the hybrid heating sources and affect the weld penetration depth greatly;On the other hand, the bead width is closely relative to laser power and the electric arc energy when the arc current is less than 150A. when the arc current is more than 150A, however, the bead width is determined by the energy of the arc only. There exists an optimal laser-arc distance (2--3mm), with which the weld bead penetration depths can be improved to 1.46--2.54 times.
Based on the research results above mentioned,the relationship between the gas concentration & shielding method and the process stability of CO_2 laser-TIG (Tungsten inert gas) hybrid welding is studied in detail. In this paper, the interaction of laser beam with electric arc was studied by the plasma images,the optical photos of the cross-sectional and the bead penetration depths & widths. The results show that the gas of coaxial nozzle can compress the plasma, which increase the welding penetration depths effectively. Otherwise the expanded plasma will absorb too much laser energy and result in unstable hybrid process with distorted electric arc.
Finally, following conclusions can be drawn up from above experimental results: the welding penetration depth can only be enhanced under the appropriate shielding gas method, and the effect of shielding gas methods on the interaction extent between laser plasma and arc plasma is the main factor for efficient synergetic effect. The pure torch method can not generate the efficient synergetic effects, and the hybrid protecting method by torch plus paraxial nozzle method has only a narrow parameter range for getting the efficient synergetic effects, while the hybrid protecting method by torch plus coaxial nozzle method can ensure the efficient synergetic effects under a considerable wide parameter range.
引文
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[30] M Hamadou,R Fabbro,G Caillibotte.Effect of gas shielding delivery mode on high power CO2 laser welding [C].San Francisco,California.Laser Welding & Brazing Proceedings of ICALEO 2004.LIA,2004.171～180
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[2] 沈惠塘.焊接技术与高招.机械工业出版社,2003.182～192,274～278
[3] 刘继常等.试析几种激光复合焊接技术.激光技术,2003,10:486～489
[4] 阿部信行,林雅一.レ-ザ·ア-ク复合溶接法の现状と将来[J].溶接学会言志,2001,70(4):7～11
[5] 牧野吉延,椎原克典,浅井知.CO2 レ+ザ·ア+クハイブリツド溶接法[J] .溶接学会言志,2001,70(4):18, 22
[6] Anatoly Khersonsky,Houston Lee. Induction heating for efficient Laser applications [J].Advanced Materrials & Process,2000,4:39～41
[7] 陈健.复合热源焊接技术的发展[J].焊接,1994,4:2～6
[8] 胡绳荪,张绍彬,赵家瑞.电弧强化激光焊[J].焊接学报,1993,14(3):159～163
[9] Onooriaki, Shinboyukie, YoshitakeAkihide,et al.Development of Laser-arc hybrid welding NKK Technical Review,2002,86(7):8～12
[10] Shigeyu,ki Nagata.Laser welding combined with TIG or MIG [C].DOC -IV-390-85
[11] 樊丁,中田一博,牛尾诚夫.激光与脉冲 MIG 复合焊接试验研究[J].应用激光,2002,22(2):169, 171
[12] Lu Dengping,Zhang Shaobin,Hu Shengsun,et al.Study on mechanism of mutual effect between laser and arc & its effect on weld penetration.China Welding,1993,2 (2):104~108
[13] 王威,王旭友.激光与电弧复合焊接技术.焊接,2004,(3):6～7
[14] Bagger C,Sondrup L C,Olsen F O.Laser/TIG hybrid welding of pot for induction heater [A].Orlando.Hybrid Laser Welding.LIA,2004.60～69
[15] Diebold T P,Albright C E.Laser-GTAW welding of aluminum alloy 5052[J].Welding journal,1980,63:18～24
[16] 倪宇.激光电弧复合焊接及激光焊接超低碳钢的焊缝磁性能研究:[硕士学位论文]。武汉:华中科技大学图书馆,2004
[17] 陈彦宾.激光—TIG 复合热源焊接物理特性研究:[ 硕士学位论文] 。 哈尔滨:哈尔滨工业大学,2003
[18] Chen Yanbin,Lei Zhenglong,Li Liqun.Study of Welding Characteristics in CO2 Laser-TIG Hybrid Welding Process.ICALEO03, 2003.41～47
[19] LIU Li-ming,WANG Ji-feng,SONG Gang.Hybrid Laser-Arc Welding of AZ31B Mg Alloy.Chinese Journal of Lasers,2004,31(2):1523～1526
[20] CHEN Yan-bin,CHEN Jie,LI Li-qun,et al.The Arc Shape& Welding Bead Characteristic of the Action of Laser&Arc.Transaction of the china Welding Institution,2003,24(2):55～56
[21] Xiao R.S,Chen K,Chen J.M.Experimental research of the plasma shielding mechanism in the process of CO2 laser welding [J].Laser Technology,2001, 25(3):238～241
[22] C Bagger,F O Olsen.Review of laser hybrid welding [J].Journal of laser applications,2005,1(17):2～14
[23] J Tusek,M Suban.Hybrid welding with arc and laser beam [J].Science and technology of welding and joining,1999,4(5):308-311
[24] C Bagger,L.C Sondrup,F.O Olsen.Laser/TIG hybrid welding of pot for induction heater [C].San Francisco,California.Hybrid Laser Welding Proceedings of ICALEO 2004.LIA,2004.60～69
[25] S Fujinaga,R Ohashi,S Katayama.Improvements of welding characteristics of aluminum alloys with YAG laser and TIG arc hybrid system [C].Miyamoto (Eds.)Proceeding of SPIE,2002,4831:301～306
[26] Tang Xiahui,Zhu Haihong,Zhu Guofu.Study of plasma control in high-power CO2 laser welding [J].Chinese journal of lasers,1997,24(2):74～178
[27] Xiao Rongshi,Mei Hanhua,Zuo Tiechuan.Influence of assistant gases on the shielding thresholds of laser induced plasma during high power CO2 laser penetration welding [J].Chinese journal of lasers,1998,25(11):1045～1050
[28] Hong lei,Wu gang,Chen Wuzhu.Influence of shielding gas flow on welding quality for CO2 laser welding of aluminum alloy [J].Chinese journal of lasers,2005,32(11): 1571～1576
[29] J tusek,M Suban.Experimental research of the effect of hydrogen in argon as a shielding gas in arc welding of high-alloy stainless steel [J].International journal of hydrogen energy,2000,25:369～376
[30] M Hamadou,R Fabbro,G Caillibotte.Effect of gas shielding delivery mode on high power CO2 laser welding [C].San Francisco,California.Laser Welding & Brazing Proceedings of ICALEO 2004.LIA,2004.171～180
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