交替双弧复合焊接工艺电弧稳定性及熔池行为研究

The key problems to increase the welding speed are: 1) Increasing the amount of deposited metal under the same conditions of heat input; 2) Reducing the temperature gradient at the weld toe. An alternating TIG+MIG double arc hybrid welding process is presented whose main arc exists between the welding wire and the base material, one end of auxiliary arc exists in the tungsten electrode and the other end switches between the welding wire and the base material. When the auxiliary arc burning between the tungsten electrode and wire, the welding heat input can be reduced and the amount of deposited metal can be increased; when the auxiliary arc burning between the tungsten electrode and the base material, the welding heat input and the energy distribution can be changed and the temperature gradient is reduced. The relatively independent control of the amount of deposited metal and heat input can be achieved by adjusting the time ratio and strength of the two states in the auxiliary arc appropriately. The control mode of "two pulse transition a droplet" is proposed. The main arc pulses are applied when drops move downwards by studying the link between the arc voltage and droplet oscillation process, which can ensure the reliability of pulse transition. An arc length control algorithm based on the alternating double arc hybrid welding process is established and optimized by selecting the appropriate signal characterization arc and using the auxiliary arc and two pulse of main arc are as an energy unit. The heat input of this process is between the single-wire welding and traditional double wire welding and the two key issues in the high-speed welding can be solved at the same time. This process provides a new possibility for the thin high-speed welding.

提高焊接速度的关键问题是：1）保证热输入相同的条件下，增大熔敷金属量；2）降低焊趾处的温度梯度。提出交替TIG+MIG双弧复合焊接工艺，其主弧存在于焊丝和母材之间，辅助弧一端在钨极上，另一端在焊丝和母材之间切换。当辅助弧在钨极和焊丝之间燃烧时，可以减小热输入，增大熔敷金属量；当辅助弧在钨极和母材之间燃烧时，可以改变热输入的大小以及能量分布方式，降低温度梯度。适当调节辅助电弧两个状态的时间比率和强度，可以实现熔敷金属量和热输入量的相对独立控制。提出"两个脉冲过渡一个熔滴"控制方式，通过研究电弧电压和熔滴振荡的关系，在熔滴向下运动时施加主弧电流脉冲，保证熔滴可靠过渡。选择合适的信号表征弧长，以辅助弧和主弧两个脉冲作为一个能量单元，建立和优化基于交替双弧复合焊接工艺的弧长控制算法。该工艺热输入介于单丝焊接和传统双丝焊接之间，可以同时解决高速焊接的两个关键问题，为薄板高速焊接提供了一种新的可能。

本课题提出了一种交替复合电弧焊接工艺方法，该工艺由一个直流MIG电弧和一个交替TIG电弧复合而成。其中MIG电弧为主电弧，建立在焊丝和母材之间；TIG电弧为辅助电弧，该电弧可以在钨极和焊丝之间，以及钨极和母材之间周期性切换。当辅助电弧在钨极和焊丝之间燃烧时，可以减小母材热输入，增大熔敷金属量；当辅助弧在钨极和母材之间燃烧时，可以改变热输入的大小以及能量分布方式，降低温度梯度。适当调节辅助电弧两个状态的时间比率和强度，可以实现熔敷金属量和热输入量的相对独立控制。.设计了一台TIG+MIG交替双弧复合焊接设备,并在此基础上提出一种弧长控制方案。利用高速摄像技术和电信号数据采集系统，总结了交替复合焊接TIG辅助电弧的特点；通过非变极性TIG复合焊接工艺电弧观察试验，分别描述了TIG电源上路持续导通和下路持续导通条件下电弧形态及简要分析其导电机理；在稳定的交替复合焊接工艺区间内，进行电弧观察试验，对TIG辅助电弧运动进行分析，并描述了TIG电源在变极性状态下的变换过程。.通过改变TIG电源的能量输入大小，实现焊丝熔敷量和母材热输入的独立控制。同时，通过与单丝MIG的焊缝成形对比，可以看出复合焊接下能够使焊接速度得到提高。