【作者】 朱玉欣；

【导师】 胡绳荪；

【作者基本信息】 天津大学 ， 材料加工工程， 2005， 硕士

【摘要】 等离子弧焊接过程中,熔池小孔的稳定性是影响等离子弧焊接过程稳定性及接头质量的重要因素。在焊接过程中,检测小孔状态并实时控制,从而提高焊接质量是当前等离子弧焊接质量控制的研究核心。本文研制开发了等离子弧焊接信号检测系统。对等离子弧焊接过程中,等离子云现象进行了深入研究,分析了等离子云现象产生的机制及其条件。指出等离子云形态变化与熔池小孔状态密切相关,通过检测等离子云形态变化可以检测熔池小孔状态。本文对探针法检测等离子云的机理、影响因素以及等离子弧焊接过程中,等离子云信号的波形特征做了深入研究。指出熔池小孔形成、闭合过程中,等离子云出现一个周期的翘摆运动,等离子云检测信号也随之出现一个负脉冲信号。研究表明,这个负脉冲信号可以作为等离子弧焊接过程中小孔状态变化的特征判据;负脉冲信号的频率则可以作为脉冲焊接是否保持“一脉一孔”焊接的特征判据。在此基础上,本文研制了实用化的多探针等离子云传感器,并利用尾焰传感器对比检验了所设计传感器的可靠性及检测精度。最后,本文以设计的等离子云传感器为基础,探讨了等离子弧焊接熔透闭环控制。结果表明,等离子云信号可以很好地反映熔池熔深以及小孔尺寸的变化,等离子云传感方法是一种实用的小孔信号传感方法。更多还原

【Abstract】 During keyhole plasma arc welding, the stability of keyhole is of criticalimportance. The quality of the welding joint and the stability of the welding processdepend strongly on the keyhole stability. It is pivotal to sense and control thekeyhole status in real time to improve the welding quality during welding process.By using the developed multi-channel signal acquisition and processing system,this paper has systematically studied the plasma cloud phenomena, analyzed themechanism and requirement of the plasma cloud’s appearance. It was founded thatthe shape change of the plasma cloud is strongly correlated with the keyhole status,and by sensing the shape change of the plasma cloud, the keyhole status could bedetected. Then the paper did systematically study on the principle and influencefactor of sensing the plasma cloud’s shape change using the metal probe. It wasfounded that no matter in DC or pulse current keyhole plasma arc welding process,during the formation and close of the keyhole, the plasma cloud will swingperiodically, and the plasma cloud signal detected will accordingly produce aundershoot This undershoot could be used as the criterion of the keyhole status, andalso the frequency of the undershoot could be used as the criterion to judge whetherthe pulse welding is one-pulse-one-keyhole. On the basis of the above study, thepaper developed an applied multi-probe plasma cloud charge sensor, and tested thereliability and precision of it comparing with the designed efflux plasma chargesensor.At last, based on the developed plasma cloud sensor, the paper studied theclose-loop penetration control of the plasma arc welding. It was shown that theplasma cloud signal detected can reflect the information of the penetration andkeyhole. All the above research concerning the plasma cloud has shown that theplasma cloud sensing is a promising and applied sensing technology in keyholeplasma arc welding.更多还原