【作者】 张树彩；

【导师】 王晓明； 赵福令；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2005， 硕士

【摘要】 电火花线切割加工(慢走丝)是一种通过浸没在液体介质(煤油或水)中的电极丝和工件之间的系列放电去除材料的热电过程。经过近半个世纪的发展,该技术已十分成熟,达到了相当高的工艺水平,并广泛应用于航空、汽车、模具及其它材料加工领域,尤其是在复杂形状的高硬度、高强度、耐高温工件的加工应用上具有相当重要的地位。 一般情况下,电火花线切割加工的加工效率是比较低的,且加工中伴有断丝的干扰,对整体的加工成本、效率及精度产生了较大影响。通过在线切割加工中附加超声振动,对解决以上问题取得了满意效果。本文首先建立了描述超声线切割复合加工中电极丝振动状态的数学模型,并计算机模拟分析了超声振动对复合加工中电极丝振动状态及放电点分布状态的影响。然后,本文结合计算机模拟分析和工艺实验,对复合加工的加工机理及工艺规律进行了研究探索。 本文得出如下结论:(1)复合加工可以明显的提高慢走丝电火花线切割加工的加工效率,其加工机理为:超声振动有利于阻止胶体系统的聚沉,改善工作液循环状态,促进放电废屑排出切缝,使极间介质及时实现消电离,从而减少稳定电弧放电、过渡放电和短路放电的发生,提高了脉冲利用率。(2)超声线切割复合加工由于减少了过渡放电和稳定电弧放电的发生以及熔融金属在工件表面的附着,可以得到较低的工件表面粗糙度和较高的工件表面质量。(3)超声振动使放电点均匀分布,避免了电极丝断丝现象的频繁发生,保证加工的稳定性、连续性及工件的加工精度。(4)超声振动造成工件的尺寸误差有所增大,使得工件的整体尺寸有所减小。 本文的研究成果对超声线切割复合加工的实际应用具有一定的指导意义,并为超声线切割复合加工技术专家系统提供了实验依据。更多还原

【Abstract】 Wire electrical discharge machining(WEDM) is a thermoelectric process whereby material is removed by a succession of electrical discharge occurring between an electrode and a workpiece which are immersed in a dielectric liquid medium(distilled water or kerosene). Through the development over the past half century, the technology has become more maturity and achieved advanced technical standard. It’s broad capabilities have allowed it to encompass aerospace,automotive and mould industries and virtually all areas of conductive material machining. Especially, WEDM has played an important role in the fields of machining exotic and high strength and temperature resistive materials with intricate shapes and profiles.Generally, the machining efficiency of WEDM is considered to be rather low, and the breakage of wire would disturb machining process that will obviously increase the production cost, reduce the machining rate and deteriorate the machining precision. This problems are solved through WEDM assisted by ultrasonic vibration of the wire. The mathematical model to describe the vibration state of wire under the action of ultrasonic vibration and discharge force has been established, through which computer simulation has been made to study the influence of ultrasonic excitation on the vibration state of wire and distribution of discharge spots. The machining mechanism and technical rules have been studied through computer simulation and experiment.The conclusions are as follows: (1) high machining efficiency can be be obtained by the compound process, the machining mechanism is: ultrasonic vibration prevent colloid system depositing in the kerf and improve dielectric circulation which facilitates machine-debris removal and dielectric deionization quickly. Therefore, short circui, transition discharging, stabilization electric arc discharging are evidently reduced and high utilization of pulse can be gained. (2) WEDM assisted Ultrasonic vibration can make surface roughness small and machined surface quality super,which is mainly attributed to: stabilization telectric arc discharging and transition discharging evidently reduce, and melted materials cohered on the surface decrease. (3) Ultrasonic vibration can make discharge spots distributed much more evenly along the span of the wire, so the breakage chance of wire can be decreased. That insure machining process more steady, continual and precise. (4) The compound process increase dimensional error of the workpiece, and reduce overall dimensions.The research in this paper will benefite the practice application of the WEDM assisted ultrasonic vibration of the wire. It brings the experiment data for the foundation of the exper system.更多还原