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作 者:孟建兵[1] 徐文骥[1] 王续跃[1] 宋文庆[1]
机构地区:[1]大连理工大学精密与特种加工教育部重点实验室,辽宁大连116024
出 处:《焊接学报》2010年第1期75-79,共5页Transactions of The China Welding Institution
基 金:国家自然科学基金(50775019)
摘 要:以外加横向交变磁场作用下的等离子体弧为研究对象,建立了等离子体弧摆动幅度和热流密度分布的数学模型.对横向交变磁约束下的等离子体弧射流特性进行理论研究,并分析工艺参数和励磁强度对横向交变磁约束等离子体弧形态和特性的影响规律.结果表明,横向交变磁场可有效控制等离子体弧形态和位置,等离子体弧在横向交变磁场作用下,分布范围增大、热流密度梯度减小.其摆动幅度随磁场强度的增加而增大,但过高的磁场强度会使等离子体弧变得不稳定;相同励磁强度下,气流量和弧电流越小、喷嘴到工件的距离越大,则摆动幅度越大;而工件表面的等离子体弧热流密度分布随励磁强度的增强趋于平坦化;相同励磁条件下,热流密度峰值随气体流量和弧电流的增大而增大、随喷嘴到工件距离的增大而减小.Two mathematical models are developed to describe the oscillating amplitude of the plasma arc along the metal surface and the heat flow density distribution of plasma arc on the metal surface respectively.The behavior of plasma arc jet under an external transverse sinusoidal alternating magnetic field imposed perpendicular to the plasma current is analyzed theoretically,and the effect of process parameters such as gas flow rate,arc current,magnetic flow density and the distance from the nozzle outlet to the anode workpiece on the form and distribution of plasma arc are also in vestigated.The results show that it is feasible to control the shape and heat flow density of the plasma arc for the transverse alternating magnetic field,which can expand the area of plasma arc thermal treatment and flat the heat flow density upon the workpiece.Furthermore,the oscillating amplitude of plasma arc increases and the heat flow density gradient upon the workpiece decreases with the magnetic flow density enhancing.However,an overly strong magnetic field coil results in the plasma arc unstable.Under the same magnetic flow density,less gas flow rate and arc current,longer distance from the nozzle outlet to the anode causes the oscillating amplitude to increase.Contrarily,the more gas flow rate and arc current,the more heat flow density peak increases.Moreover,longer distance from nozzle outlet to workpiece descends the heat flow density peak.
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