调压式真空注型充型速度智能调控方法研究

针对真空注型(Vacuum casting，VC)浇注件由于充型速度不稳定所导致的翘曲变形质量缺陷，提出调压式真空注型工艺，并分析压力充型机理，论证压力差是影响充型速度的关键工艺参数，并通过分析阀口开度和充型速度的关系制定了充型速度控制策略。详细介绍该控制策略的实现过程，包括：对浇注件的STL模型进行体素化，并获取模腔的体积及横截面面积等特征；采用控制体积法对充型过程进行数值模拟，获得理论的阀口开度调节曲线；构建阀口开度模糊控制器，并利用二维查询表实现模糊推理过程，提高了控制器的响应速度，减小超调量。利用自主研制的试验平台结合具体实例进行试验，试验结果充分体现了调压式真空注型工艺的优势，证明了控制策略的可行性，大大提高了浇注件质量，为真空注型技术提供了一种新的工艺方法。

Study on the Intelligent Control Method of Filling Velocity Oriented to Adjustable Pressure Vacuum Casting

The warpage quality defect of vacuum casting (VC) parts is usually caused by unstable filling velocity, so the adjustable pressure VC process is proposed. The filling mechanism is analyzed, it is demonstrated that the differential pressure is the key process parameter which affect filling velocity. The filling velocity control strategy is developed by analyzing the relationship between valve opening and filling velocity. The strategy implementation process is introduced. The voxel model of VC part is constructed based on STL model and the features of cavity such as volume and cross sectional area are obtained. In order to gain the theoretical control curve of valve opening, the numerical simulation of mold filling process is carried out adopting control volume method. The fuzzy logic controller (FLC) of valve opening is constructed which using two-dimensional table to realize fuzzy inference, thus the respond speed is quick and the overshoot is low. Finally, combined with concrete examples, the experiments are carried out using test experiment platform. The experiments results fully reflected the advantages of adjustable pressure VC process and proved the feasibility of control strategy and improved the quality of VC parts. In a word, the method is new and useful process for VC technology.