真空环境下的智能注型机理及可控制造与试验研究

With the ongoing enhancement of capability for developing new product in China, the Vacuuming Casting (VC) technology has been increasingly applied in more and more fields. Furthermore, the quality demands from customers are constantly increasing. Therefore, solving bottleneck problems affecting the development of VC technology has great research significance and will present good market prospect. Centered on improving product quality of casting parts, a new kind of pressure regulating process for DPVCM is studied in this research project. Based on math model of two-phase, high viscosity and non-Newtonian fluid mixing process obtained through computational fluid dynamics theory, the mixing effect exerted by mixer structure and mixing speed on materials can be probed. Through studying math model of mould filling process established by reaction kinetics, thermodynamics, chemorheology and high polymer material theory, the effect of process parameters on part quality will be researched. Having obtained geometrical characteristic of casting parts after slicing STL model, the mould filling model can be built and the relationship between geometrical characteristic and mould filling parameters could be studied. Combining case reasoning theory, neural network reasoning with fuzzy controlling technology, intelligent controlling system of filling process can be constructed, making intelligent recommendation and correction of process parameters possible. Finally, the experimental platform will be built to test the validity and feasibility of aforementioned theories and technologies.

随着我国新产品开发能力的不断加强，真空注型技术的应用越来越广泛，客户对浇注件质量的要求也越来越高，因此解决影响真空注型技术发展的瓶颈，具有较高的理论研究价值和良好的市场前景。本项目围绕提高真空注型浇注件质量这一主题，提出一种新型压力可调式真空注型工艺；运用计算流体动力学理论建立两相高粘度非牛顿流体混合过程数学模型，研究搅拌器结构及搅拌速度对材料混合效果的影响；根据反应动力学、热力学、化学流变学以及高分子材料理论建立充模过程的数学模型，研究注型参数对浇注件质量的影响；采用STL模型切片法获取浇注件几何特征，建立充模过程模型，研究几何特征和充模参数间的关系；结合基于实例推理、神经网络推理和模糊控制技术构建浇注过程智能控制系统，实现浇注过程参数的智能推荐和修正；最后，搭建试验平台验证研究所得的理论成果、技术实现手段和方法的正确性及可行性。

本项目以提高真空注型浇注件质量为目标，结合了特征识别、计算机仿真、优化设计和智能控制等技术，提出了一种新型的调压式真空注型工艺。该工艺可以根据浇注件的几何特征调控压差值，在变压作用下使得充型过程中材料的前沿速度保持稳定，从而改善了浇注件的翘曲缺陷。主要研究成果如下：1）利用计算流体力学建立了两相高粘度非牛顿流体混合过程的数学模型，并对双组份聚氨酯材料混合过程进行了仿真分析和实验验证，优化了搅拌叶的结构和搅拌转速，提高了材料的混合质量。2）对充模过程进行了机理分析，确定了上下腔室的压力差是影响充模前沿速度的决定性因素，并制定了依据模腔拓扑特征获取压力实时调控曲线以保持充模速度恒定的控制策略。3）采用STL模型切片法获取模腔横截面面积，建立了压力差-模腔截面积-充型速度的关系模型，并开发了基于VB的自动控制系统，验证研究所得的理论成果、技术实现手段和方法的正确性及可行性。总之，本项目研究了工艺参数优化及控制方法，并搭建了实验平台，为真空注型装备向智能化、数字化方向发展提供了理论基础和技术支持。