【作者】 王辉；

【导师】 曲迎东；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2010， 硕士

【摘要】 喷射成形是近年来发展极其迅速的金属和合金成形新技术,该工艺制成的材料具有晶粒细小、组织均匀并能抑制偏析等快速凝固材料的特点,其中雾化质量是影响喷射成形产品质量的重要因素之一。本文首次将静电雾化技术和喷射成形结合在一起,最终目的是使金属液荷电、利用静电力强化雾化过程,从而改善雾化质量。本研究主要工作内容为:设计了金属液荷电的喷射成形装置,采用FLUENT软件对喷射成形工艺中静电作用下气体流场进行了模拟,获得了各种参数对雾化过程的影响规律,同时进行了部分实验验证。在静电雾化过程中,一般具有三种雾滴带电方式,即电晕充电、感应充电和接触充电。本文设计的金属液充电装置以感应充电为主、接触充电为辅,设计的充电系统为:电源的一极通过电极棒与金属液接触,使其带负电,另一极与石墨垫片接触,使其带正电,从而形成一个电容,对内部的液滴进行感应荷电。电源装置是本研究工作的一个重要方面,为此设计了可调直流电源装置,主要包括电压范围在0—300V的调压器、整流桥、电解电容和电容、电流表、电压表。本文将静电作用应用到喷射成形工艺过程中,建立了电场作用下气体流场的模型。在Fluent软件中,导入电磁场模块,引入电场的作用,从而实现对喷射成形工艺中静电作用下气体流场的模拟。模拟结果表明,在静电作用下雾化区域的压强的分布更加均匀、集中,气流速度由300m/s提高到700m/s,高速气流对金属液雾化是起积极作用的,说明静电作用后能有效地提高金属液的雾化效果。在上述数值模拟结果的基础上,对加入压强为1.0MPa、电压为200V和压强为1.0MPa、电压为0V时情况分别做了实验,实验结果与模拟结果基本一致。当压强为1.0MPa,电压为200V时,能得到较好的雾化效果,轴向的压强分布更加均匀、集中,有利于减少了液滴的飞溅,而且在喷嘴出口处负压减小,降低了金属液反喷的可能性。更多还原

【Abstract】 Spray forming is a new forming technology of metals and alloys which is extremely rapid development in recent year, the perform produced by spray forming has rapid solidification characteristics of grain refining, tissue uniformity and inhibition of segregation, for spray forming process, atomization quality is a important factor that effect the quality of spray forming product. In this paper, the application of electrostatic atomization technology in spray forming will be present, aim is to make liquid alloy charging and use electrostatic force to reinforce atomizing process, furthermore, the atomization quality can be improved. The main research work is following: Firstly, design charging system of spray forming device; Then electrostatic interaction on gas flow field in spray forming is simulated, effect of some parameter on atomization process under electrostatic is discussed, and some experimental verification are present.There are three mode making droplet charged in electrostatic atomization process: corona charging, induction charging and contact charging. In this paper, the designed charging device mainly use inductive charging mode, few used contact charging mode,this charging device can be described: One pole of power contact with metal liquid through electrode bar, it is negative, the other pole of power contact with graphite gasket, it is positive, then between two poles built a capacitor, it will be induction charged while liquid alloy moved through capacitor. The design of direct current power device is an important equipment, so a optional direct current power device is designed, it mainly include adjustable voltage regulator ranged between 0-300V, rectifier bridge, electrolytic capacitors and capacitance, ammeter, voltmeter.Electrostatic interaction is applied to spray forming in this paper, the gas flow field model in the electric field is built. In FlUENT software, MHD modules is used, it can introduce electric field effect, then the electrostatic interaction of gas flow field in spray forming is simulated. Simulation results show that the distribution of atomization area pressure is more uniform and concentrate, the velocity is increased from 300m/s to 700m/s. It is explained that electrostatic has active effect on atomization process, and atomization quality of liquid metal can be improved under electrostatic field.On the basis of numerical simulation results, experimental of pressure is 1MPa, voltage is 200V and pressure is 1MPa, voltage is 0V are present, it is satisfied that the experimental results are consist with the simulated results. While pressure is 1.0MPa, voltage is 200V, there are a satisfied atomization phenomenon, axial pressure distribution is more uniform and concentrate, it helps to reduce the droplets splash and negative pressure at the nozzle decreases, the possibility of liquid metal anti-spray is decreased too.更多还原