双立式爆炸焊接R-δ型可焊性窗口

针对双立式爆炸焊接新方法的爆轰驱动特点,通过研究双立式爆炸焊接条件下的焊接下限、焊接上限、临界起爆厚度、临界碰撞角和临界复板厚度等可焊性边界条件,构建了一种静态参数下的双立式爆炸焊接R-δ型可焊性窗口;该窗口综合反映了爆炸焊接中的复板特性和炸药特性两大焊接参数,所建立的铜、不锈钢、铝合金等材料的双立式爆炸焊接R-δ型可焊性窗口可直接运用于工程实践中;根据双立式爆炸焊接R-δ型可焊性窗口设置的15 mm超低药量试验下的304L/Q235b复合板实现了高质量的微小波状结合,说明该窗口可以作为确定双立式爆炸焊接工艺参数的依据.     

Effect of welding speed and electrode extension on the approximate entropy of welding current in short-circuiting GMAW

Based on the phase space reconstruction of welding current in short-circuiting transfer arc welding under carbon dioxide, the approximate entropy of welding current and its standard deviation have been calculated and analyzed at different welding speeds and different electrode extensions respectively. The experimental and calculated results show that at a certain arc voltage, wire feeding rate and gas flow rate, welding speed and electrode extension have significant effects not only on the approximate entropy of welding current, but also on the stability of welding process. Further analysis proves that when the welding speed and electrode extension are in an appropriate range respectively, the welding current approximate entropy attains maximum and its standard deviation minimum. Just under such circumstances, the welding process is in the most stable state.     

Test for random in electrical signals time series of CO2 short circuit transition welding process by the method of surrogate data 

This paper introduced the basic theory and algorithm of the surrogate data method, which proposed a rigorous way to detect the random and seemingly stochastic characteristics in a system. The Gaussian data and the Rossler data were used to show the availability and effectivity of this method. According to the analysis by this method based on the short- circuiting current signals under the conditions of the same voltage and different wire feed speeds, it is demonstrated that the electrical signals time series exhibit apparently randomness when the welding parameters do not match. However, the electrical signals time series are deterministic when a match is found. The stability of short-circuiting transfer process could be judged exactly by the method of surrogate data.