摘要
根据几十年焊接研究人员的宝贵成果和经验，在穿孔型等离子弧焊接过程中，小孔的稳定性是影响小孔型等离子弧焊接过程稳定性及接头质量的重要因素，是影响该焊接方法应用的瓶颈。因此，在小孔等离子弧焊接中，检测小孔状态并对其进行实时控制，从而提高焊接质量是该领域研究的前沿。
本文就穿孔型等离子弧焊接过程进行了高速摄影，在视觉上直观地看到了等离子弧反翘和小孔的变化情况。并对等离子弧反翘产生的力学机理、等离子弧反翘的变化规律作了分析，从而得出等离子弧反翘可以作为等离子弧焊接熔透信息的特征量的结论。为了能够更有效地对等离子弧焊接进行检测和熔透控制，本文提出了一种新的而且实用性强的无源探针等离子弧反翘检测方法与装置，并自行设计等离子弧反翘的动态扫描装置，确定无源探针检测等离子弧反翘的最佳探针摆放位置，为准确、有效检测等离子弧反翘提供了方法上的保证。
在合理焊接工艺参数正常焊接过程中，小孔变化具有同周期变化的规律。在本试验条件下，小孔形成的周期是10ms，相应的等离子弧反翘电压检测波形也是周期性变化，其周期也是10ms，而且其峰值电压时间为4ms，基值时间为6ms。因此，检测电压的周期、峰值时间、基值时间都可以作为小孔信号的特征值用于等离子弧小孔焊接熔透控制。
最后分别从稳定焊接过程中的等离子弧反翘的波形、受到干扰的焊接过程中的等离子弧反翘的波形两个方面，对等离子弧反翘的电压信号进行实时采集和分析。实验证明，此方法在等离子弧焊检测和熔透控制上简单、准确、有效。
According to valuable achievements and experiences for many years, the stability of the keyhole plays an important role on the welding stability and joint quality. Therefore, the control of the keyhole in real-time can be gotten by means of detecting the state of the keyhole during keyhole plasma arc welding, it is a short cut to improve the welding quality in the research field of plasma arc welding.
The paper did photograph to keyhole plasma arc welding, we can easily see the change state between the plasma cloud and keyhole. In addition, we draw a conclusion that plasma cloud is the feature of the keyhole by the analysis to the mechanics of forming plasma cloud and the change rule of plasma cloud. In order to control the penetration of plasma arc welding effectively, this paper has provided a new method of detecting plasma cloud without power as well as corresponding device, a dynamic scanning machine is designed to find the optimal position of detecting plasma cloud, which ensures detecting plasma cloud effectively and accurately.
The change of keyhole has periodic law, And the period is 10ms in the test condition, corresponding change of the plasma cloud is the same. The peak time is 4ms, and the backhand time is 6ms. Therefore, the period, the peak time, and the backhand time are all the character of the keyhole in the penetration control of plasma arc.
At last, this paper realizes the detect and penetration control of plasma arc welding by acquiring voltage signal of plasma cloud, and the reality must be on the basis of two voltages, one is in stable welding process, the other is in unstable welding process. It is verified experimentally that the new method is sample, accurate and effective in the penetration control of plasma arc welding.
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