Numerical analysis of keyhole establishment time in keyhole plasma arc welding

Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional transient model is developed to analyze the evolutions of keyhole shape and keyhole establishment time in continuous current plasma arc welding process. Firstly, a combined volumetric heat source model is used to simulate the transient variation of temperature field. And then the surfaced formation equation is adopted to calculate dynamic features of the keyhole shape and keyhole establishment time inside weld pool, in which the force action on weld pool surface is considered. Experiment is conducted to validate the numerical simulation results. The predicted keyhole size and keyhole establishment time are in agreement with the experimental measurement. And the calculated fusion zone geometry is consistent with the measured one.     

多孔塑料管材挤出工艺和机头模具

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构件强度不是控制条件，构件失稳才昆色对控制条件，因此构年的强度试验没有必要在铁塔试验中进行。只要不是新型结构的铁塔，用真型铁塔进行验证性试验完全可以保证使用的可靠性，根本没有必要贴庆变片。试验加荷时，除最大控制工况荷载加至极限荷载值外，其余非控制工况均无此必要。     

Numerical analysis of transient keyhole shape in pulsed current plasma arc welding

Based on the characteristics of ＂one keyhole in a pulse＂ in pulsed current plasma arc welding （PAW） , the transient variation process of weld pool in a pulse cycle is simulated through the establishment of corresponding heat source model. And considering the effects of gravitational force, plasma arc pressure and surface tension on the weld pool surface, the dynamic change features of the keyhole shape in a pulse cycle are calculated by using surface deformation equation. Experiments are conducted and validate that the calctdated weld fusion line is in good agreement with the experimental results.     

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东营市某容积为50000m3大型油罐建成运行2年后,罐基础环墙出现了不均匀沉降,罐底塌陷变形,安全隐患严重。针对该罐体的结构特点和地质特性,经过研究分析,采取了新型的施工工艺和综合灌浆方法,消除了工程隐患,取得了比较满意的加固效果。加固处理后,工程经过2年的投产运行实践,证明该工艺方法安全可靠,科学合理。     

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