【作者】 韩俭；

【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】 小孔型等离子弧焊接是一种高能高效焊接方法,具有十分广阔的应用前景。由于等离子弧焊接工艺参数匹配区间窄,使得等离子弧焊接中小孔的稳定性差,因此等离子弧焊接过程及接头质量的稳定性差。如何提高等离子弧焊接的稳定性是当前该领域研究的前沿课题之一。小孔型等离子弧焊熔透控制的关键是对小孔状态进行控制,而控制小孔状态的关键是控制焊接过程的热输入量。采用脉冲焊接的方式可以有效地控制热输入量。等离子弧焊接熔透控制系统通常为复杂的非线性系统,很难建立准确的熔透控制数学模型,因而采用传统的控制方法不能得到令人满意的控制效果。智能控制理论为等离子弧焊熔透控制开辟了新天地。本文建立了脉冲等离子弧焊接模糊控制系统的仿真数学模型,并采用MATLAB软件对模糊控制系统进行仿真。另外,本文研制了一套以AVR ATmega128单片机为核心的脉冲等离子弧焊接模糊控制系统,实现了脉冲等离子弧焊熔透过程的模糊控制。该系统不仅可以进行脉冲等离子弧焊接工艺参数的设定,而且可以根据检测到的焊接过程中小孔状态信息对脉冲电流参数进行实时调节,实现了对焊缝熔透的实时控制。该系统实现了脉冲等离子弧焊过程“一脉一孔”的智能控制,焊缝成形美观。实验表明,仿真和实际施焊的结果有良好的一致性。这说明了基于单片机的脉冲等离子弧焊接模糊控制系统的数学模型是正确的; 所研制开发的软、硬件系统的工作是可靠的。更多还原

【Abstract】 Keyhole Plasma Arc Welding (PAW) is a high-octane and high-efficiency technology, it has a wide foreground. However, the welding technologic parameters matching zone of PAW is so narrow that it makes the keyhole unstable, which leads to the instability of the welding process and the joint quality. Therefore, how to improve welding stability is a promising problem in the research field of PAW. The key of penetration control in Keyhole PAW is to control the state of the keyhole, and in order to control the state of the keyhole, it is important to control the heat input of welding process. Pulse welding method is effective to control heat input. Because of the non-linear characteristic of PAW penetration control system, it is hard to establish the exact mathematics model of penetration control. Thereby, the adoption of traditional control means can’t be satisfying. The intelligent control theory creates a new world for penetration control of PAW. The simulation mathematics model of Pulse Plasma Arc Welding (PPAW) fuzzy control system is established, which later is simulated with the software of MATLAB in the paper. PPAW fuzzy control system based on the single-chip of AVR ATmega128, which achieves fuzzy control in PPAW penetration process, is also designed in the paper. The system can not only establish the welding technologic parameters, but also regulate pulse current parameters in real time on the basis of the state of keyhole which is detected in welding process, and in this way, it is able to be used to control penetration of welded joint in real time. The system realizes both intelligent control which is called “one pulse one keyhole” in PPAW process and uniformity of welded joint. The results of experiments indicate that there is favorable consistency between the simulation and the practical welding. So the mathematics model of PPAW fuzzy control system based on the single-chip is correct, and the software and hardware empoldered are credible.更多还原