On-Line Estimation of Laser Weld Penetration
On-Line Estimation of Laser Weld Penetration
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DOI：
10.1115/1.2802392
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发表时间：
1997-12
影响因子：
1.7
通讯作者：
J. Tu;K. Lankalapalli;M. Gartner;K. Leong
中科院分区：
文献类型：
--
作者：
J. Tu;K. Lankalapalli;M. Gartner;K. Leong
大功率CO2激光焊接因其生产率高、焊接质量好而在工业上得到了广泛的应用。为了充分挖掘这一工艺的潜力，必须拥有在线的焊接质量检测方法，以提高工艺的生产率和可靠性，实现100%的焊缝检测。焊缝熔深是影响激光焊接质量的重要因素之一。然而，在不对工件进行剖切的情况下，很难直接测量穿透的程度。本文提出了一种适用于生产环境的基于模型的侵彻深度估算技术。该模型将测量到的工件底表面温度、焊缝宽度、激光功率和焊接速度与熔透深度联系起来。闭环深度估计器将模型与模型误差补偿器相结合，以补偿激光功率和吸收率测量中的不确定度。考虑的其他影响包括由于传感器的有限大小而导致的平均、基于传感器位置以及过程和传感器动态的延迟。为了验证静态工艺模型和深度估算方案的有效性，在低碳钢板上进行了多次堆焊和对接焊接。用红外热电偶测量了焊接过程中工件底表面的温度。对焊缝进行纵向剖分，以获得熔透轮廓。深度估计器估算的侵彻剖面与实测的侵彻剖面吻合较好。结果验证了所提出的深度估计器估计侵彻深度的能力和跟踪侵彻深度动态变化的能力。
High-power CO{sub 2} laser welding has been widely used in the industry because of its high productivity and excellent weld quality. In order to tap the potential of this process completely, it is important to have on-line weld quality inspection methods to improve the process productivity and reliability by achieving 100 percent weld inspection. Weld penetration is one of the most important factors critical to the quality of a laser weld. However, it is very difficult to directly measure the extent of penetration without sectioning the workpiece. In this paper a model-based penetration depth estimation technique suitable for the production environment is developed. The proposed model relates the temperature measured on the bottom surface of the workpiece, weld bead width, laser beam power and welding speed to penetration depth. The closed-loop depth estimator combines the model and a model-error compensator to compensate for the uncertainty in the measurement of the laser power and absorptivity. Other effects considered are the averaging due to the finite size of the sensor, delay based on the sensor location and the process and sensor dynamics. Several bead-on-plate and butt welds were made on low carbon steel plates to validate the static process models and themore » depth estimation scheme. Temperatures on the bottom surface of the workpiece during welding were measured using infrared thermocouples. The welds were sectioned longitudinally to obtain the penetration profile. The penetration profiles estimated by the depth estimator matched satisfactorily with the measured penetration profiles. The results validate the capability of the proposed depth estimator to estimate penetration depth and its ability to trace the dynamic changes in penetration depth.« less