【作者】 刘磊；

【导师】 张义顺； 李德元； 董晓强；

【作者基本信息】 沈阳工业大学 ， 材料学， 2006， 硕士

【摘要】 等离子MIG焊是利用等离子电弧和MIG电弧在同一个焊枪中燃烧,以获得焊缝熔深和熔宽合理分配,并且具有高的焊接质量和焊接效率的一种先进的焊接方法。 与一般的单电弧焊接方法相比,等离子MIG焊的电弧形态要复杂的多。为了分析电弧组态出现的规律,本文利用ANSYS有限元分析软件模拟了电弧空间的流动和温度分布,然后又利用气体击穿的相关理论与实际观察相比较,分析了各种电弧形态出现的规律,并因此改进了等离子MIG焊接枪体,再利用该枪体进行了焊接实验。 首先,应用气体击穿理论分析了等离子MIG复合电弧条件下的起弧和稳弧过程,提出了用帕邢自变量Pd/T判定等离子电弧起弧位置的方法。利用帕邢理论成功地解释了等离子电弧借助MIG电弧产生的导电通道起弧的过程,并在实验中观察到了这一现象。通过对电弧空间流场和温度场模拟,结合帕邢自变量的比较,探讨了导弧点位置,尺寸,及焊道余高、电弧拖曳和喷嘴挂滴等几种情况对等离子电弧起弧和稳定的影响。 然后,依据于理论分析,改进了现有的等离子—MIG焊接枪体,设计了一种强压缩型等离子—MIG枪体,重新设计了引弧过程。这种枪体将两个电弧压缩成一个直径很小的同轴电弧,使电弧具有很强的穿透力和搅拌熔池作用,特别适合于大厚度铝制工件的焊接。 最后,使用强压缩型等离子—MIG枪体,在改变MIG电流、MIG电压、等离子电流等的实验条件下进行了焊接实验,对枪体改进的效果进行了验证。更多还原

【Abstract】 Plasma-MIG welding is a kind of advanced welding method, which uses plasma-arc and MIG-arc burning in the same blowtorch, so that weld-penetration and melting-width are properly distributed, and it can get high welding quality and efficency.In contrast with general welding method of single arc, the forms of Plasma-MIG welding arc are more complicated. In order to analyse the rule of striking the welding arc, this paper made use of ANSYS infinite element analysis software to simulate the fluid and temperature distribution of arc space, and used correlative theory of gas breakdown to compare with practical observation, analysed the rule of striking the welding arc, improved the welding gun of Plasma-MIG, in the end, under various experimental conditions, it made welding experiment.First, through the theory of gas breakdown, under the case of Plasma-MIG complex arcs, it analysed the process of striking the welding arc and arc’s stability, and put forward a new method, which made use of Paschen’s independent variable Pd/T to determine the position of striking the plasma-arc. Through Paschen’s theory, it succeeded in explaining the process how the plasma-arc strikes. Through the simulation of arc spatial fluid and temperature field simulation and comparison of Paschen’ s independent variable, it studied the impacts on striking the plasma-arc and arc’s stability when in case of various guiding-arc-point’s position, dimension, height of weld path , daggling of welding arc and nozzle’s drop etc.Secondly, according to the theory analysis, it improved the existing Plasma-MIG welding torch, redesigned the process of striking the welding arc. This torch compresses the double arcs to small-radius’s arcs with the same axis, thus in this case, this kind of welding arc has great power of penetration and effect of beating up the melt pool, so it’s fit for the welding of almuniu with big thickness.Finally, under various experimental conditions, such as changing MIG’s current> MIG’s voltage ■> plasma’s current etc, it made some welding experiments, and verified the effect of improvement of welding torch.更多还原