压铸过程超声处理系统的研究

发布时间：2018-05-04 17:01

本文选题：超声 + 压铸　；参考：《北京交通大学》2014年硕士论文

【摘要】：摘要：晶粒尺寸是决定金属材料性能的主要因素,晶粒细化方法有很多,本文中用到的是超声处理法。超声处理细化晶粒主要是依靠超声空化作用局部的瞬时高温高压以及强烈冲击波,打碎枝晶生长,并配合超声声流效应、热效应等,提高形核率,细化晶粒。本文重点对超声探头以及超声波处理仪进行介绍,超声探头设计主要包括超声探头的结构设计、工艺参数设计以及壳体安装设计,超声波处理仪主要介绍其工作所处特殊压铸条件及其功能与工作流程。另外本文还对实验数据进行分析,并对现有超声处理系统存在的问题进行总结。本文还对实验样品的金相和力学性能做观察分析,实验数据并不能很好吻合超声处理与金属晶粒细化之间的关系。其主要原因有以下两点：一是超声探头工作频率发生偏移,进而影响超声功率输出,而超声频率和功率是影响金属晶粒细化效果的主要参数；二是由于超声探头位于压铸腔内,造成处理时间过短,仅为几十毫秒,超声作用不明显。针对以上两点原因提出对策：第一,增设频率自动跟踪装置,使得超声波处理仪自动跟踪超声探头的负载,并调节至最佳频率；第二,改变超声探头安装位置,增加超声处理时间。
[Abstract]:Abstract: grain size is the main factor to determine the properties of metal materials. There are many methods for grain refinement. Ultrasonic treatment is used in this paper. Ultrasonic treatment mainly depends on local instantaneous high temperature and high pressure and strong shock wave of ultrasonic cavitation to break dendrite growth and cooperate with ultrasonic acoustic flow effect and thermal effect to increase nucleation rate and refine grain. This paper mainly introduces the ultrasonic probe and the ultrasonic processing instrument. The ultrasonic probe design mainly includes the structure design, the process parameter design and the shell installation design of the ultrasonic probe. The special die-casting condition, function and working flow of ultrasonic instrument are introduced. In addition, the experimental data are analyzed, and the existing problems of ultrasonic processing system are summarized. The metallographic and mechanical properties of the experimental samples are also observed and analyzed. The experimental data do not agree well with the relationship between ultrasonic treatment and grain refinement. The main reasons are as follows: first, the frequency of ultrasonic probe is offset, which affects the output of ultrasonic power, and the frequency and power of ultrasonic are the main parameters that affect the effect of grain refinement of metal, and the second is that the ultrasonic probe is located in the die casting cavity. The treatment time is too short, only tens of milliseconds, ultrasonic action is not obvious. In view of the above two reasons, the following countermeasures are put forward: first, the frequency automatic tracking device is added to make the ultrasonic processor automatically track the load of the ultrasonic probe and adjust to the optimum frequency; second, the installation position of the ultrasonic probe is changed. Increase ultrasonic treatment time.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TG249.2;TB552

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