薄板激光深熔焊接熔透模式的机理研究
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摘要
匙孔和熔池相互作用是激光深熔焊接中的核心问题。本文通过分析Nd:YAG激光焊接过程中匙孔、熔池及等离子体的温度、电子密度特征,建立了同轴视觉传感系统,对焊接过程中熔池和匙孔区域的光辐射进行了实时检测。利用匙孔和熔池区域的光辐射特征,结合焊缝的特征对薄板激光深熔焊接的熔透模式进行了深入的研究,系统地分析了不同熔透模式下匙孔、熔池和焊缝的特征随工艺参数变化的规律,从理论上揭示了熔透模式转变的物理机制和对焊缝成形的影响规律。
本文将焊接过程中匙孔和熔池的光辐射特征与焊缝的横截面特征联系起来,对全熔透激光焊接的熔透模式进行了划分。根据匙孔是否穿透工件的背面将激光深熔焊接分为匙孔穿透型和匙孔未穿透型两种熔透模式。匙孔穿透型熔透时的焊缝典型的横截面形状为“X”型,而匙孔未穿透模式时的典型焊缝横截面形状为“V”型。通过分析匙孔内部的受力平衡,对两种熔透模式相互转化时匙孔底部的力学平衡的变化进行了探讨;结合焊接工艺参数对匙孔存在和扩展的影响规律,确定了工艺参数对熔透模式转变的影响,通过熔池的受热状态和流体驱动力两个方面对两种熔透模式下焊缝的形成机制进行了阐述。
对于试验获得的同轴视觉传感图像,利用中值平滑滤波、同态滤波及线性灰度变换等图像预处理方案对图像进行了除噪和增强处理,使用Canny算子实现了匙孔和熔池的边缘检测,并通过Hough变换最终获得了匙孔和熔池的形状特征。对匙孔、熔池和焊缝特征随工艺参数变化的研究表明:相对于激光功率,焊接速度是影响匙孔和熔池角度的决定因素;熔合线下部与激光轴线的夹角、焊缝背面宽度与正面宽度的比Rw可以作为判断熔透模式的特征量。在熔透模式为匙孔未穿透型时,熔池下部与激光轴线的夹角为正,一旦实现了匙孔穿透,该角度即变为负角度。工件厚度为1.4mm时,Rw大于0.55即可获得稳定的匙孔穿透型焊接模式。
采用从同轴视觉传感图像所获得的熔池边缘特征来进行焊缝正面熔宽的检测,检测的结果与试验的结果具有较高的吻合度;利用匙孔背面开口的特征进行焊缝背面熔宽的检测,在匙孔背面开口较小的时候,两者近似呈现线性关系,但随着背面半径的增加,焊缝背面的宽度渐渐趋向稳定。
在工艺试验的基础上,通过考虑匙孔机制在激光深熔焊接中的作用,将由同轴视觉传感系统获得的匙孔特征引入到数值计算中,并在此基础上建立了移动热源作用下的激光深熔焊接熔池传热传质的三维数学模型。研究了不同熔透模式下熔池内部的温度场和速度场的分布,并对熔池流动驱动力的作用进行了量化的分析。模拟的结果表明,不同熔透模式下,由于匙孔形状的差别使得熔池内部的流体运动产生了较大的差别,从而是两种焊缝形状形成的内在原因;在熔池内部的驱动力中,浮力所引起的流体运动速度较慢,对熔池流动的影响很弱;蒸气摩擦力主要影响的是匙孔周围熔池的流动,促使熔池金属由匙孔壁向熔池的边缘流动;表面张力是熔池中流体流动的最主要的驱动力,在其作用下熔池表面的液态金属由熔池中心流向边缘,并在熔池后方边缘处形成涡流。匙孔穿透工件时,表面张力作用下的熔池形成束腰,是形成“X”型焊缝的主要原因。
The interaction between the keyhole and weld pool is the core problem of the laser keyhole welding. By analysis of the keyhole, weld pool and plasma temperature character and electron density character, a coaxial visual sensing system was established to detect the optical emission of the keyhole and weld pool in deep penetration laser welding process. Using the optical character of the keyhole and the weld pool, incorporate with the weld cross section character, the penetration mode of the thin sheet laser welding was studied. And the variation of the keyhole, weld pool and weld character with the processing parameter was analyzed, the physical mechanics of the penetration mode transition and its effect on the weld shape was represented theoretically.
In this paper, the optical emission character of the keyhole and the weld pool was related to the weld cross section character, and the penetration mode of the laser full penetration welding was classified. Based on the situation of the keyhole whether full penetrated the workpiece, two penetration modes of the laser full penetration welding was represented, as open keyhole penetration mode and close keyhole penetration mode. The typical weld cross section of the open keyhole penetration mode is“X”type, the typical weld cross section of the close keyhole penetration mode is“V”type. With the transition of the penetration mode, the variety of the force equilibration at keyhole bottom was discussed. Combined with the relation between the process parameter to the keyhole existing and expansion, the effect of the process parameter on penetration mode transition was illuminated, and the weld formation mechanics for different penetration mode was explained by the heating situation and fluid driving force of the weld pool.
For the coaxial visual sensing image in experiments, the Media filter, homomorphic filter and Linear gray stretch were used to eliminate noise and enhance processing. The Canny operator was applied to detect the edge of the keyhole and the weld pool. Finally, the Hough transformation was utilized to obtain shape character of the keyhole and the weld pool surface. The result of the keyhole, weld pool and the weld cross section shape characters according to the process parameter shown that the welding speed is the governing factor of the keyhole and weld pool shape angle, the included angle between undersides fusion-line and laser beam and the weld width ratio can be the characters to identify the penetration mode. In close keyhole penetration mode, the included angle between undersides fusion-line is positive, as the penetration mode transit to open keyhole penetration mode, the corresponding included angle is negative. As the workpiece thickness is 1.4mm, the weld width ratio greater than 0.55 indicates that the stable open keyhole penetration mode was obtained.
The detection of the weld obverse width was achieved by the weld pool edge characters, which is represented in the coaxial visual sensing image. The detection result was agreed with the experimental result fairly. The character of the keyhole rear opening was applied to detection of the weld rear width. As the smaller keyhole rear opening size, the relation between the keyhole rear opening size and the weld rear width is approximate lineally. As the increasing of the keyhole rear opening size, the weld rear width tends to stable.
Based on the technological experiment, the effect of the keyhole mechanics on welding process was considered, and the keyhole characters of the coaxial visual sensing image were introduced to the numerical simulation process, a three-dimensional mathematic model of the heat and mass transfer with the moving heat source in laser keyhole welding was developed. The temperature field and fluid flow vector field for different penetration mode was calculated, and the effect of the fluid flow driving forces was analyzed quantificational. The result of the numerical simulation demonstrated that the difference of the keyhole shape lead to the difference of the weld pool fluid flow pattern, which is the internal reason for the weld shapes formation in different penetration mode. For the driving force of the fluid flow, as the flow speed caused by the buoyancy is feeble, the effect of the buoyancy on the weld pool flow can be neglected. The fluid flow caused by the vapor friction is limited around the keyhole, which drive the fluid from the keyhole wall flow to the outer edge of the weld pool. The surface tension is the main driving force in the weld pool. Under the govern of the surface tension, the liquid metal of the weld pool surface flowed from the weld pool center to the edge, and an eddy flow was formed at the back of the weld pool. In open keyhole penetration mode, the surface tension is the key factor for the formation of the“X”type weld cross section.
本文将焊接过程中匙孔和熔池的光辐射特征与焊缝的横截面特征联系起来,对全熔透激光焊接的熔透模式进行了划分。根据匙孔是否穿透工件的背面将激光深熔焊接分为匙孔穿透型和匙孔未穿透型两种熔透模式。匙孔穿透型熔透时的焊缝典型的横截面形状为“X”型,而匙孔未穿透模式时的典型焊缝横截面形状为“V”型。通过分析匙孔内部的受力平衡,对两种熔透模式相互转化时匙孔底部的力学平衡的变化进行了探讨;结合焊接工艺参数对匙孔存在和扩展的影响规律,确定了工艺参数对熔透模式转变的影响,通过熔池的受热状态和流体驱动力两个方面对两种熔透模式下焊缝的形成机制进行了阐述。
对于试验获得的同轴视觉传感图像,利用中值平滑滤波、同态滤波及线性灰度变换等图像预处理方案对图像进行了除噪和增强处理,使用Canny算子实现了匙孔和熔池的边缘检测,并通过Hough变换最终获得了匙孔和熔池的形状特征。对匙孔、熔池和焊缝特征随工艺参数变化的研究表明:相对于激光功率,焊接速度是影响匙孔和熔池角度的决定因素;熔合线下部与激光轴线的夹角、焊缝背面宽度与正面宽度的比Rw可以作为判断熔透模式的特征量。在熔透模式为匙孔未穿透型时,熔池下部与激光轴线的夹角为正,一旦实现了匙孔穿透,该角度即变为负角度。工件厚度为1.4mm时,Rw大于0.55即可获得稳定的匙孔穿透型焊接模式。
采用从同轴视觉传感图像所获得的熔池边缘特征来进行焊缝正面熔宽的检测,检测的结果与试验的结果具有较高的吻合度;利用匙孔背面开口的特征进行焊缝背面熔宽的检测,在匙孔背面开口较小的时候,两者近似呈现线性关系,但随着背面半径的增加,焊缝背面的宽度渐渐趋向稳定。
在工艺试验的基础上,通过考虑匙孔机制在激光深熔焊接中的作用,将由同轴视觉传感系统获得的匙孔特征引入到数值计算中,并在此基础上建立了移动热源作用下的激光深熔焊接熔池传热传质的三维数学模型。研究了不同熔透模式下熔池内部的温度场和速度场的分布,并对熔池流动驱动力的作用进行了量化的分析。模拟的结果表明,不同熔透模式下,由于匙孔形状的差别使得熔池内部的流体运动产生了较大的差别,从而是两种焊缝形状形成的内在原因;在熔池内部的驱动力中,浮力所引起的流体运动速度较慢,对熔池流动的影响很弱;蒸气摩擦力主要影响的是匙孔周围熔池的流动,促使熔池金属由匙孔壁向熔池的边缘流动;表面张力是熔池中流体流动的最主要的驱动力,在其作用下熔池表面的液态金属由熔池中心流向边缘,并在熔池后方边缘处形成涡流。匙孔穿透工件时,表面张力作用下的熔池形成束腰,是形成“X”型焊缝的主要原因。
The interaction between the keyhole and weld pool is the core problem of the laser keyhole welding. By analysis of the keyhole, weld pool and plasma temperature character and electron density character, a coaxial visual sensing system was established to detect the optical emission of the keyhole and weld pool in deep penetration laser welding process. Using the optical character of the keyhole and the weld pool, incorporate with the weld cross section character, the penetration mode of the thin sheet laser welding was studied. And the variation of the keyhole, weld pool and weld character with the processing parameter was analyzed, the physical mechanics of the penetration mode transition and its effect on the weld shape was represented theoretically.
In this paper, the optical emission character of the keyhole and the weld pool was related to the weld cross section character, and the penetration mode of the laser full penetration welding was classified. Based on the situation of the keyhole whether full penetrated the workpiece, two penetration modes of the laser full penetration welding was represented, as open keyhole penetration mode and close keyhole penetration mode. The typical weld cross section of the open keyhole penetration mode is“X”type, the typical weld cross section of the close keyhole penetration mode is“V”type. With the transition of the penetration mode, the variety of the force equilibration at keyhole bottom was discussed. Combined with the relation between the process parameter to the keyhole existing and expansion, the effect of the process parameter on penetration mode transition was illuminated, and the weld formation mechanics for different penetration mode was explained by the heating situation and fluid driving force of the weld pool.
For the coaxial visual sensing image in experiments, the Media filter, homomorphic filter and Linear gray stretch were used to eliminate noise and enhance processing. The Canny operator was applied to detect the edge of the keyhole and the weld pool. Finally, the Hough transformation was utilized to obtain shape character of the keyhole and the weld pool surface. The result of the keyhole, weld pool and the weld cross section shape characters according to the process parameter shown that the welding speed is the governing factor of the keyhole and weld pool shape angle, the included angle between undersides fusion-line and laser beam and the weld width ratio can be the characters to identify the penetration mode. In close keyhole penetration mode, the included angle between undersides fusion-line is positive, as the penetration mode transit to open keyhole penetration mode, the corresponding included angle is negative. As the workpiece thickness is 1.4mm, the weld width ratio greater than 0.55 indicates that the stable open keyhole penetration mode was obtained.
The detection of the weld obverse width was achieved by the weld pool edge characters, which is represented in the coaxial visual sensing image. The detection result was agreed with the experimental result fairly. The character of the keyhole rear opening was applied to detection of the weld rear width. As the smaller keyhole rear opening size, the relation between the keyhole rear opening size and the weld rear width is approximate lineally. As the increasing of the keyhole rear opening size, the weld rear width tends to stable.
Based on the technological experiment, the effect of the keyhole mechanics on welding process was considered, and the keyhole characters of the coaxial visual sensing image were introduced to the numerical simulation process, a three-dimensional mathematic model of the heat and mass transfer with the moving heat source in laser keyhole welding was developed. The temperature field and fluid flow vector field for different penetration mode was calculated, and the effect of the fluid flow driving forces was analyzed quantificational. The result of the numerical simulation demonstrated that the difference of the keyhole shape lead to the difference of the weld pool fluid flow pattern, which is the internal reason for the weld shapes formation in different penetration mode. For the driving force of the fluid flow, as the flow speed caused by the buoyancy is feeble, the effect of the buoyancy on the weld pool flow can be neglected. The fluid flow caused by the vapor friction is limited around the keyhole, which drive the fluid from the keyhole wall flow to the outer edge of the weld pool. The surface tension is the main driving force in the weld pool. Under the govern of the surface tension, the liquid metal of the weld pool surface flowed from the weld pool center to the edge, and an eddy flow was formed at the back of the weld pool. In open keyhole penetration mode, the surface tension is the key factor for the formation of the“X”type weld cross section.
引文
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53 K. Seiji, S. Naoki, et al. X-Ray Transmission In-Situ Observation of Keyhole during Laser Spot Welding and Pulse-Shaping for Prevention of Porosity. 20th International Congress on Applications of Lasers & Electro-Optics (ICALEO2001). 2001. Jacksonville, Florida USA1003-1011
54 M. Beck, P. Berger, et al. Aspects of Keyhole/Melt Interaction in High Speed Laser Welding. 1991. Madrid, Spain: Pub by Int Soc for Optical Engineering, Bellingham, WA, USA: 769
55 T. Fuhrich, P. Berger, and H. Hugel. Marangoni Effect in Laser Deep Penetration Welding of Steel. Journal of Laser Applications, 2001. 13(5): 178-186
56 M. Kern, P. Berger, and H. Hugel. Magneto-Fluid Dynamic Control of Seam Quality in CO2 Laser Beam Welding. Welding Journal (Miami, Fla), 2000. 79(3): 72-78
57 W. Sudnik, D. Radaj, and W. Erofeew. Computerized Simulation of Laser Beam Welding, Modelling and Verification. Journal of Physics D: Applied Physics, 1996. 29: 2811-2815
58 W. Sudnik, D. Radaj, and W. Erofeew. Computerized Simulation of Laser Beam Weld Formation Comprising Joint Gaps. Journal of Physics D: Applied Physics, 1998. 31: 3475-3480
59 W. Sudnik, D. Radaj, et al. Numerical Simulation of Weld Pool Geometry in Laser Beam Welding. Journal of Physics D: Applied Physics, 2000. 33(6): 662-671
60 V.V. Semak, W.D. Bragg, et al. Transient Model for the Keyhole during Laser Welding. Journal of Physics D: Applied Physics, 1999. 32(15): 61-64
61 A. Matsunawa and V. Semak. Simulation of Front Keyhole Wall Dynamicsduring Laser Welding. Journal of Physics D: Applied Physics, 1997. 30(5): 798-809
62 V. Semak and A. Matsunawa. The Role of Recoil Pressure in Energy Balance during Laser Materials Processing. Journal of Physics D: Applied Physics, 1997. 30(18): 2541-2552
63 R. Fabbro and K. Chouf. Dynamical Description of the Keyhole in Deep Penetration Laser Welding. Journal of Laser Applications, 2000. 12(4): 142
64 R. Fabbro and K. Chouf. Keyhole Modeling during Laser Welding. Journal of Applied Physics, 2000. 87(9): 4075
65 R. Fabbro. Basic Processes in Deep Penetration Laser Welding. in 21st international Congress on Applications of Lasers & Electro-Optics(ICALEO 2002). 2002. Scottsdale, Arizona, USA11p
66 R. Fabbro, S. Slimani, et al. Study of Keyhole Behavior for Full Penetration Nd-Yag CW Laser Welding. Journal of Physics D: Applied Physics, 2005. 38(12): 1881-1887
67 G.A. Taylor, M. Hughes, et al. Finite Volume Methods Applied to the Computational Modeling of Welding Phenomena. Applied Mathematical Modelling, 2002. 26(2): 311-322
68 G. Brueggemann, A. Mahrle, and T. Benziger. Comparison of Experimental Determined and Numerical Simulated Temperature Field for Quality Assurance at Laser Beam Welding of Steels and Aluminum Alloying. NDT and E International, 2000. 33(7): 453-463
69 A. Mahrle and J. Schmidt. The Influence of Fluid Flow Phenomena on the Laser Beam Welding Process. International Journal of Heat and Fluid Flow, 2002. 23: 288-297
70 A. Mahrle and J. Schmidt. Numerical Simulation of Heat Transfer during Deep Penetration Laser Beam Welding. Advanced Computational Methods in Heat Transfer, Heat Transfer V, Computational Mechanics. 1998. Southampton, Boston233-242
71 H. Ki, P.S. Mohanty, and J. Mazumder. Multiple Reflection and its Influence on Keyhole Evolution. Journal of Laser Applications, 2002. 14(1): 39
72 H. Ki, P.S. Mohanty, and J. Mazumder. Modeling of Laser KeyholeWelding: Part I. Mathematical Modeling, Numerical Methodology, Role of Recoil Pressure, Multiple Reflections, and Free Surface Evolution. Metallurgical and Materials Transactions A, 2002. 33: 1817-1830
73 H. Ki, P.S. Mohanty, and J. Mazumder. Modeling of Laser Keyhole Welding: Part II. Simulation of Keyhole Evolution, Velocity, Temperature Profile, and Experimental Verification. Metallurgical and Materials Transactions A, 2002. 33: 1831
74 K. H., M. J., and M. PS. Modelling of High-density Laser-material Interaction Using Fast Level Set Method. J. Phys. D: Appl. Phys., 2001. 34(3): 364-372
75 S. Kaierle, P. Abels, et al. State of the Art and New Advances in Process Control for Laser Materials Processing. 20th International Congress on Applications of Lasers & Electro-Optics, ICALEO 2001. 2001. Jacksonville, Florida USA. 1012-1022
76 M. Kogel-Hollacher and C. Dietz. Process Monitoring or Process Control in Laser Material Processing. 20th International Congress on Applications of Lasers & Electro-Optics, ICALEO 2001. 2001. Jacksonville, Florida USA, 1194-1200
77 J.P. Boillot, X. Yu, et al. Automatic Welding Using Laser-based 3D Vision Systems. Welding in the World, Le Soudage Dans Le Monde, 1994. 34: 173-182
78 D. Frechette, E. Berthiaume, and S. Lapierre. Application of Process Monitoring and Quality Control of Laser-Welded Blanks Using an Integrated Multiple-Sensors Approach. Laser Materials Processing Conference ICALEO 2000. 2000. Dearborn, MI USA. 35-43
79 D. Wildmann. On-line Quality System Assures Highest Production Reliability of Laser Welded Blanks. Laser Institute of America Conference on Laser Materials Processing Process Diagnostics and Control. 1998. Orlando, FL USA
80 D. Wildmann, M. Halschka, and J. Schwarz. Novel Methods for Online High-Accuracy Quality Control of Laser Welded Blank sand Tubes. Laser Materials Processing Conference, ICALEO 2000. 2000. Dearborn, MI USA. 62-71
81 A. Matsunawa, N. Seto, et al. Dynamics of Keyhole and Molten Pool in high power CO2 laser welding. High-Power Lasers in Manufacturing. 1999. Osaka, Japan. 34-45
82 J. Petereit, P. Abels, et al. Failure Recognition and Online Process Control in Laser Beam Welding. 21st International Congress on Applications of Lasers & Electro-Optics. 2002 Scottsdale, Arizona, USA. 10p
83 C. Kratzsch, P. Abels, et al. Coaxial Process Control during Laser Beam Welding of Tailored Blanks. Proceedings of SPIE. 2000. 472-482
84 G. Qin, X. Qi, et al. Acquisition and Processing of Coaxial Image of Molten Pool and Keyhole in Nd:YAG Laser Welding with High Power. China Welding (English Edition), 2004. 13(1): 51
85 秦国梁, 林尚扬. 激光深熔焊接过程中小孔径向尺寸及其动特性. 中国激光, 2005. 32(4): 557-561
86 A. Wilson. CMOS Camera Checks Automotive Laser Welds. Vision Systems Design, 2004. 9(6): 35-37
87 J. Beersiek. On-line Monitoring of Keyhole Instabilities during Laser Beam Welding. Laser Materials Processing Conference ICALEO '99. 1999. SanDiego, CA USA. D49-58
88 J. Beersiek. A CMOS Camera as a Tool for Pprocess Analysis not only for Laser Beam Welding. 20th International Congress on Applications of Lasers & Electro-Optics(ICALEO 2001). 2001. Jacksonville, Florida USA. 1185-1193
89 J. Beersiek. New aspects of Monitoring with a CMOS Camera for Laser Materials Processing. 21st International Congress on Applications of Lasers & Electro-Optics(ICALEO2002). 2002. Scottsdale, Arizona, USA. 11p
90 F. Bardin, P. Aubry, et al. Evaluation of Coaxial Process Control Systems for Nd:YAG Laser Welding in Aeronautics Application. 21st International Congress on Applications of Lasers & Electro-Optics. 2002. Scottsdale, Arizona, USA. 11p
91 J. Greses, P. A. Hilton. Laser-Vapour Interaction in High-Power CW Nd:YAG Laser Welding. 22nd International Congress on Applications of Lasers & Electro-Optics. 2003. Jacksonville, Florida, USA. 163-172
92 D. Lacroix, G. Jeandel, et al. Spectroscopic Characterization of Laser-induced Plasma Created during Welding with a Pulsed Nd:YAG Laser. Journal of Applied Physics. 1997, 81(10): 6599-6603
93 J. O. Connolly, G. J. Beirne, et al. Optical Monitoring of Laser Generated Plasma during Laser Welding. Proceedings of SPIE - The International Society for Optical Engineering. 2000, 3935: 132-138
94 秦国梁, 徐晨明, 董红刚等. 大功率 Nd:YAG 激光深熔焊接过程中同轴辐射光的采集. 应用激光. 2003. 23(4): 205-208
95 陈凤东. 基于图像法激光焊接等离子体、熔池及匙孔特征分析. 哈尔滨工业大学硕士学位论文. 2003: 15
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104 A. Mahrle, J. Schmidt. The Influence of Fluid Flow Phenomena on theLaser Beam Welding Process. International Journal of Heat and Fluid Flow. 2002. 23: 288-297
105 S. V. 帕坦卡著, 张政译. 传热与流体流动的数值计算. 科学出版社. 1984: 26
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7 W. Zhang, Modeling the Formation and Collapse of a Keyhole during Laser Welding Process. 2003, University of Missouri – Rolla
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13 M.Y. Krasnoperov, R.R.G.M. Pieters. Solidification Features of the Thin Steels in Keyhole Welding. 22nd International Congress on Applications of Lasers & Electro-Optics. 2003. Jacksonville, Florida USA. P509
14 M.Y. Krasnoperov, R.R.G.M. Pieters, I.M. Richardson. Weld Pool Geometry during Keyhole Laser Welding of Thin Steel Sheets. Science and Technology of Welding & Joining, 2004(9): 501-506
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18 F. Rick, G. Reinhart, B. Lenz. Process Prototyping for Laser Material Processing - Advanced Finite Element Models for the Simulation of Laser Welding. Proc. of the 17th intern. Congress on Applications of Lasers & Electro-Optics (ICALEO'98). 1998. Orlando / FL
19 B. Lenz, G. Reinhart, and F. Rick. Process Prototyping - Finite Element Modeling of the Laser Welding Process. Lasers in Engineering, LAENEG, 1998. 7(3-4): 253-264
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22 W. Sudnik, D. Radaj. Numerical Simulation of Weld Pool Geometry in Laser Beam Welding. Journal of Physics D: Applied Physics, 2000. 33: 662-671
23 V. Kamala, J.A. Goldak. Error Due to Two Dimensional Approximation in Heat Transfer Analysis of welds. Welding Journal (Miami, Fla), 1999. 72(9): 440-446
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26 J. Mazumder and W.M. Steen. Heat Transfer Model for CW Laser Material Processing. Journal of Applied Physics, 1980. 51(2): 941
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29 王成. 激光深熔焊接热循环的研究. 电焊机, 2001. 31(4): 14-15
30 J.A. Goldak. Computer Modeling of Heat Flow in Welds. Met Trans B, 1986. 17B: 587-600
31 S.S. Glickstein and E. Friedman. Characterization and Modeling of the Heat Source. ASM Handbook, 2002(6): 1-10
32 M.R. Frewin and D.A. Scott. Finite Element Model of Pulsed Laser Welding. Welding Journal (Miami, Fla), 1999. 78(1): 15--22
33 J. Milewski and E. Sklar. Modeling and Validation of Multiple Reflections for Enhanced Laser Welding. Modeling and Simulation in Materials Science and Engineering, 1996. 4(3): 305-322
34 陈涛, 王智勇. 脉冲激光焊接的数学模型. 焊接学报, 2001. 22(2): 9-14
35 J.O. Milewski, M.B. Barbe. Modeling and Analysis of Laser Melting within a Narrow Groove Weld Joint. Welding Journal (Miami, Fla), 1999. 78(4): 109-115
36 J.Y. Lee, S.H. Ko, et al. Mechanism of Keyhole Formation and Stability in Stationary Laser welding. Journal of Physics D: Applied Physics, 2002. 35(13): 1570-1576
37 R. Fabbro and K. Chouf. Keyhole Description in Deep Penetration Laser Welding. 2000. Osaka, Jpn: Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, USA: 104-112
38 E.H. Amara and A. Bendib. Modeling of Vapour Flow in Deep Penetration Laser Welding. Journal of Physics D: Applied Physics, 2002. 35(3): 272-280
39 J.O. Milewski and T.M. Mustaleski. Modeling of Laser Energy Concentration in Narrow Gap Joints. 1998. Pine Mountain, GA, United States: ASM International: 437-441
40 S. Fujii, N. Takahashi, et al. Development of 2D Simulation Model forLaser Welding. 2000. Osaka, Jpn: Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, USA: 218
41 G. Reinhart; F. Auer; and B. Lenz. Simulation Models to Predict Process and Component Characteristics with Laser Welding. LaserOpto. 2000, 32(6): 64-67
42 F. Rick, G. Reinhart, and H. Lindl. Simulation Techniques as Tool for Laser Oriented Product Design. Rapid Prototyping Meeting. 1996. Micropolis, Besancon, France 43-52
43 F. Rick, G. Reinhart, and B. Lenz. Process Prototyping for Laser Material Processing-Advanced Finite Element Models for the Simulation of Laser Welding. 17th International Conference on the Application of Laser and Electro-Optics (ICALEO ’98). 1998. Orlando/Florida, USA158-167
44 F. Rick, G. Reinhart, and B. Lenz. FEM-Simulation of Laser Welding in Production Planning and Product Design. Proc. of the 6th intern. Conference on Sheet Metal (SheMet98). 1998. Enschede. Twente University 267-274
45 B. Lenz, G. Reinhart, and F. Rick. Process Prototyping of Manufacturing Processes. Scholz, Reiter u.a. (Hrsg.): Process Modelling. 1999, Berlin: Springer. 360-369
46 A. Matsunawa and S. Katayama. Understanding Physical Mechanisms in Laser Welding for Construction of Mathematical Model. Welding Research Abroad, 2003. 49(4): 27
47 S. Katayama and A. Matsunawa. Microfocused X-ray Transmission Real-time Observation of Laser Welding Phenomena. Yosetsu Gakkai Shi/Journal of the Japan Welding Society, 2001. 70(6): 17
48 S. Naoki, K. Seiji, and M. Akira. Porosity Formation Mechanism and Reduction Method in CO2 Laser Welding ofStainless Steel. 溶接学会論文集, 2000. 19(4): 600-609
49 M. Mizutani, S. Katayama, and A. Matsunawa. Observation of Molten Metal Behavior during Laser Irradiation - Basic Experiment to Understand Laser Welding Phenomena. 2002. Osaka, Japan: The International Society for Optical Engineering: 208-212
50 Y. Shimokusu, S. Fukumoto, et al. Application of 7 kW Class High PowerYttrium-Aluminum-Garnet Laser Welding to Stainless Steel Tanks. Journal of Laser Applications, 2002. 14(2): 68-72
51 A. Matsunawa and S. Katayama. Keyhole Instability and its Relation to Porosity Formation in High Power Laser Welding. 2001. Indianapolis, IN, United States: ASM International: 8-13
52 A. Matsunawa, N. Seto, et al. Dynamics of Keyhole and Molten Pool in High Power CO2 Laser Welding. 2000. Osaka, Jpn: Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, USA: 34-40
53 K. Seiji, S. Naoki, et al. X-Ray Transmission In-Situ Observation of Keyhole during Laser Spot Welding and Pulse-Shaping for Prevention of Porosity. 20th International Congress on Applications of Lasers & Electro-Optics (ICALEO2001). 2001. Jacksonville, Florida USA1003-1011
54 M. Beck, P. Berger, et al. Aspects of Keyhole/Melt Interaction in High Speed Laser Welding. 1991. Madrid, Spain: Pub by Int Soc for Optical Engineering, Bellingham, WA, USA: 769
55 T. Fuhrich, P. Berger, and H. Hugel. Marangoni Effect in Laser Deep Penetration Welding of Steel. Journal of Laser Applications, 2001. 13(5): 178-186
56 M. Kern, P. Berger, and H. Hugel. Magneto-Fluid Dynamic Control of Seam Quality in CO2 Laser Beam Welding. Welding Journal (Miami, Fla), 2000. 79(3): 72-78
57 W. Sudnik, D. Radaj, and W. Erofeew. Computerized Simulation of Laser Beam Welding, Modelling and Verification. Journal of Physics D: Applied Physics, 1996. 29: 2811-2815
58 W. Sudnik, D. Radaj, and W. Erofeew. Computerized Simulation of Laser Beam Weld Formation Comprising Joint Gaps. Journal of Physics D: Applied Physics, 1998. 31: 3475-3480
59 W. Sudnik, D. Radaj, et al. Numerical Simulation of Weld Pool Geometry in Laser Beam Welding. Journal of Physics D: Applied Physics, 2000. 33(6): 662-671
60 V.V. Semak, W.D. Bragg, et al. Transient Model for the Keyhole during Laser Welding. Journal of Physics D: Applied Physics, 1999. 32(15): 61-64
61 A. Matsunawa and V. Semak. Simulation of Front Keyhole Wall Dynamicsduring Laser Welding. Journal of Physics D: Applied Physics, 1997. 30(5): 798-809
62 V. Semak and A. Matsunawa. The Role of Recoil Pressure in Energy Balance during Laser Materials Processing. Journal of Physics D: Applied Physics, 1997. 30(18): 2541-2552
63 R. Fabbro and K. Chouf. Dynamical Description of the Keyhole in Deep Penetration Laser Welding. Journal of Laser Applications, 2000. 12(4): 142
64 R. Fabbro and K. Chouf. Keyhole Modeling during Laser Welding. Journal of Applied Physics, 2000. 87(9): 4075
65 R. Fabbro. Basic Processes in Deep Penetration Laser Welding. in 21st international Congress on Applications of Lasers & Electro-Optics(ICALEO 2002). 2002. Scottsdale, Arizona, USA11p
66 R. Fabbro, S. Slimani, et al. Study of Keyhole Behavior for Full Penetration Nd-Yag CW Laser Welding. Journal of Physics D: Applied Physics, 2005. 38(12): 1881-1887
67 G.A. Taylor, M. Hughes, et al. Finite Volume Methods Applied to the Computational Modeling of Welding Phenomena. Applied Mathematical Modelling, 2002. 26(2): 311-322
68 G. Brueggemann, A. Mahrle, and T. Benziger. Comparison of Experimental Determined and Numerical Simulated Temperature Field for Quality Assurance at Laser Beam Welding of Steels and Aluminum Alloying. NDT and E International, 2000. 33(7): 453-463
69 A. Mahrle and J. Schmidt. The Influence of Fluid Flow Phenomena on the Laser Beam Welding Process. International Journal of Heat and Fluid Flow, 2002. 23: 288-297
70 A. Mahrle and J. Schmidt. Numerical Simulation of Heat Transfer during Deep Penetration Laser Beam Welding. Advanced Computational Methods in Heat Transfer, Heat Transfer V, Computational Mechanics. 1998. Southampton, Boston233-242
71 H. Ki, P.S. Mohanty, and J. Mazumder. Multiple Reflection and its Influence on Keyhole Evolution. Journal of Laser Applications, 2002. 14(1): 39
72 H. Ki, P.S. Mohanty, and J. Mazumder. Modeling of Laser KeyholeWelding: Part I. Mathematical Modeling, Numerical Methodology, Role of Recoil Pressure, Multiple Reflections, and Free Surface Evolution. Metallurgical and Materials Transactions A, 2002. 33: 1817-1830
73 H. Ki, P.S. Mohanty, and J. Mazumder. Modeling of Laser Keyhole Welding: Part II. Simulation of Keyhole Evolution, Velocity, Temperature Profile, and Experimental Verification. Metallurgical and Materials Transactions A, 2002. 33: 1831
74 K. H., M. J., and M. PS. Modelling of High-density Laser-material Interaction Using Fast Level Set Method. J. Phys. D: Appl. Phys., 2001. 34(3): 364-372
75 S. Kaierle, P. Abels, et al. State of the Art and New Advances in Process Control for Laser Materials Processing. 20th International Congress on Applications of Lasers & Electro-Optics, ICALEO 2001. 2001. Jacksonville, Florida USA. 1012-1022
76 M. Kogel-Hollacher and C. Dietz. Process Monitoring or Process Control in Laser Material Processing. 20th International Congress on Applications of Lasers & Electro-Optics, ICALEO 2001. 2001. Jacksonville, Florida USA, 1194-1200
77 J.P. Boillot, X. Yu, et al. Automatic Welding Using Laser-based 3D Vision Systems. Welding in the World, Le Soudage Dans Le Monde, 1994. 34: 173-182
78 D. Frechette, E. Berthiaume, and S. Lapierre. Application of Process Monitoring and Quality Control of Laser-Welded Blanks Using an Integrated Multiple-Sensors Approach. Laser Materials Processing Conference ICALEO 2000. 2000. Dearborn, MI USA. 35-43
79 D. Wildmann. On-line Quality System Assures Highest Production Reliability of Laser Welded Blanks. Laser Institute of America Conference on Laser Materials Processing Process Diagnostics and Control. 1998. Orlando, FL USA
80 D. Wildmann, M. Halschka, and J. Schwarz. Novel Methods for Online High-Accuracy Quality Control of Laser Welded Blank sand Tubes. Laser Materials Processing Conference, ICALEO 2000. 2000. Dearborn, MI USA. 62-71
81 A. Matsunawa, N. Seto, et al. Dynamics of Keyhole and Molten Pool in high power CO2 laser welding. High-Power Lasers in Manufacturing. 1999. Osaka, Japan. 34-45
82 J. Petereit, P. Abels, et al. Failure Recognition and Online Process Control in Laser Beam Welding. 21st International Congress on Applications of Lasers & Electro-Optics. 2002 Scottsdale, Arizona, USA. 10p
83 C. Kratzsch, P. Abels, et al. Coaxial Process Control during Laser Beam Welding of Tailored Blanks. Proceedings of SPIE. 2000. 472-482
84 G. Qin, X. Qi, et al. Acquisition and Processing of Coaxial Image of Molten Pool and Keyhole in Nd:YAG Laser Welding with High Power. China Welding (English Edition), 2004. 13(1): 51
85 秦国梁, 林尚扬. 激光深熔焊接过程中小孔径向尺寸及其动特性. 中国激光, 2005. 32(4): 557-561
86 A. Wilson. CMOS Camera Checks Automotive Laser Welds. Vision Systems Design, 2004. 9(6): 35-37
87 J. Beersiek. On-line Monitoring of Keyhole Instabilities during Laser Beam Welding. Laser Materials Processing Conference ICALEO '99. 1999. SanDiego, CA USA. D49-58
88 J. Beersiek. A CMOS Camera as a Tool for Pprocess Analysis not only for Laser Beam Welding. 20th International Congress on Applications of Lasers & Electro-Optics(ICALEO 2001). 2001. Jacksonville, Florida USA. 1185-1193
89 J. Beersiek. New aspects of Monitoring with a CMOS Camera for Laser Materials Processing. 21st International Congress on Applications of Lasers & Electro-Optics(ICALEO2002). 2002. Scottsdale, Arizona, USA. 11p
90 F. Bardin, P. Aubry, et al. Evaluation of Coaxial Process Control Systems for Nd:YAG Laser Welding in Aeronautics Application. 21st International Congress on Applications of Lasers & Electro-Optics. 2002. Scottsdale, Arizona, USA. 11p
91 J. Greses, P. A. Hilton. Laser-Vapour Interaction in High-Power CW Nd:YAG Laser Welding. 22nd International Congress on Applications of Lasers & Electro-Optics. 2003. Jacksonville, Florida, USA. 163-172
92 D. Lacroix, G. Jeandel, et al. Spectroscopic Characterization of Laser-induced Plasma Created during Welding with a Pulsed Nd:YAG Laser. Journal of Applied Physics. 1997, 81(10): 6599-6603
93 J. O. Connolly, G. J. Beirne, et al. Optical Monitoring of Laser Generated Plasma during Laser Welding. Proceedings of SPIE - The International Society for Optical Engineering. 2000, 3935: 132-138
94 秦国梁, 徐晨明, 董红刚等. 大功率 Nd:YAG 激光深熔焊接过程中同轴辐射光的采集. 应用激光. 2003. 23(4): 205-208
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