TIG焊熔池外激谐振与熔透的关系

薄板TIG 焊时,利用脉动电流引起熔池振荡,当脉动电流与一定尺寸熔池自然振荡频率相同时,则熔池产生谐振,造成电弧长度及电弧电压有较大的往复变化。对电弧电压变动部分进行滤波,放大并用计算机采样,发现当熔池谐振时,电弧电压变动部分达到最大幅值,谐振后幅值很快衰减。本文以熔池谐振信号做为熔透信息进行熔透控制,给出了脉动电流电源,计算机检测系统。研究了熔透信号的变化规律及影响因素,在定点电弧及对接焊时,熔池尺寸与熔池谐振频率有较好的对应关系;以焊接电弧做为传感器,用熔池谐振频率控制熔透及熔池尺寸,有很好的重复性及较高的精度,这对解决熔透闭环自适应控制有很大的实际意义。

RELATIONSHIP BETWEEN THE WELD POOL RESONANCE AND THE WELD FULL PENETRATION IN TIG WELDING

The weld pool oscillation can be excited by fluctuating welding current inthin plate TIG welding.When the fluctuating current frequency is identical withthe natural frequency of the weld pool,the resonance of the weld pool is pro-duced so that the arc length and the arc voltage will be changed at same time.The variable parts of the arc voltage are filtered,amplified and monitored by acomputer.It is found that during the weld pool resonance,the amplitude ofvariable parts of the arc voltage becomes maximum then it is decreased obvi-ously.Using the weld pool resonance as singnals to control the weld full penet-ration is possible.In this paper,the measuring system consisting of a fluctuat-ing current power source and a computer monitor unit is introduced.The re-gularity of the weld pool resonance and its influence factors are studied.Thereis a good corresponding relationship between the weld pool size and the weldpool resonance frequency in stationary arc and butt welding.Using weld arc asa sensor through the weld pool resonance signals to control the weld full pene-tration,there are good repeatability and high accuracy.The method developedin this paper offers a promising prospect for solving the weld full penetrationadaptive control.