CO2半短路过渡焊电弧电压自寻优智能控制

针对细丝短路过渡焊,采用以实现最高短路过渡频率为目标的自寻优模糊控制,可以使电弧电压与唯一设定值焊接电流形成优化匹配获得最高短路过渡频率,达到稳定熔滴过渡、减少飞溅和改善成形的目的.但试验发现这一控制策略用于半短路过渡焊,则无论电流选多大,电弧电压常维持在20V左右,所焊焊缝熔宽窄,余高大,熔深浅.显然,对于半短路过渡焊的电弧电压仍采用以实现最高短路过渡频率为寻优目标的控制策略是不够全面的.针对这一情况,研制了一种以可编程控制器(PLC)为核心器件,通过自主开发软件自动实现对半短路过渡焊电弧电压寻优的智能控制.系统以实现较高短路频率和较长燃弧占空比为复合寻优目标,对电弧电压进行优选法和变步长法分段自寻优,寻优后的电弧电压与设定的焊接电流形成优化匹配,获得稳定的半短路过渡过程.

Arc Voltage Self-optimizing Intelligent Control System for Carbon Dioxide Half Short-circuiting Transfer Welding

With a self optimizing fuzzy control system for CO 2 arc welding with filament wire,the arc voltage can be optimized for certain given arc current to realize the maximum short circuiting transfer frequency.Consequently,the stability of droplets transfer can be improved to reduce the spatter and improve the formation of weld bead.However,the experimental results revealed that under the half short circuiting droplet transfer the arc voltage is generally maintained at about 20V with such control system despite arc current,which results in the formation of the narrow weld bead with a shallow penetration and large reinforcement.This fact suggests that there is a certain limitation with the self optimizing fuzzy control of arc voltage only for the maximum short circuiting transfer frequency.Therefore a new control system with the intelligent control through a PLC (programmable logical controller) was developed to realize the self optimizing control of arc voltage in half short circuiting welding.The system was primarily based on the control of arc voltage to search for both the higher transfer frequency and the longer ratio of burning arc time and short circuit time with variable steps.With such an optimization method,the optimized arc voltage was matched well with a given arc current to achieve a stable half short circuiting droplet transfer.