面向熔射制模的直接快递制造耐高温原型技术基础研究

发布时间：2018-11-08 06:56

【摘要】：多品种、小批量、快速化的制造发展趋势要求企业必须快速响应市场和用户的需求变化,随着快速制模技术的不断深入及其在工业领域尤其在在汽车行业中的广泛应用,要求进一步大幅度提高模具制造效率,降低成本。本文针对等离子熔射制模技术中的耐高温原型制造问题,提出直接快速铣削粘土类耐高温复合材料原型,减少原工艺中的复杂繁冗,以及翻制过程中的精度丢失。为此,以粘土类耐高温原型为研究对象,以传统铣削加工技术为理论支撑,从粘土类材料的设计、材料的干燥、材料的加工性能及其加工工艺参数等出发,设计了粘土-莫来石耐高温原型复合材料,系统地研究了粘土类陶瓷材料在加工过程中的相关基础理论、方法及关键技术。本文的主要研究内容和创新性成果如下： 1.分析了快速制模技术发展现状及存在的问题,针对等离子熔射制模技术中耐高温原型通过硅胶模翻制的工艺,工艺复杂并且原型在翻制过程中精度容易丢失的问题,创新性的提出了面向等离子熔射制模的直接快速制造耐高温原型工艺,有效简化了工艺流程。 2.分析了陶瓷材料的加工技术现状,创新性地提出未焙烧粘土材料的直接加工工艺。针对未焙烧粘土质地软、切屑粘刀、不易装夹等问题,本文采用干燥处理,通过干燥实验和理论分析制定了合理的干燥制度,实验证明干燥后粘土类陶瓷材料强度提高,适合在机床装夹及切屑不粘刀；进行了粘土材料的可加工性研究,分析了粘土原型的表面质量、铣削力大小与加工参数的关系,同时进行了材料的培烧工艺及收缩特性的研究。 3.针对纯粘土材料的抗热震性差及培烧后收缩变形大等问题,本文进一步采用粘土莫来石复合材料制作耐高温原型的工艺,研究以聚乙烯醇为粘结剂的耐高温复合材料的粘结机理。通过改变粘土材料、耐火材料莫来石的配比以及含水量,研究上述两个参数对材料抗弯强度以及培烧收缩性的影响。结果表明：随着莫来石及水的含量的增加,材料干燥后抗弯强度降低；确定合理的含水量后,莫来石含量增加,焙烧后收缩减小,最终确定了耐高温复合材料中合理的莫来石含量及含水量。 4.对于制备的耐高温原型复合材料进行了可加工性研究,提出以弯曲强度(如3所述),切屑形态以及表面质量来评价材料的可加工性。切屑形状呈细长条状,受加工参数的影响不大。在研究了主轴转速、进给速度和轴向切削深度等加工参数对干燥后耐高温原型表面粗糙度的影响基础上,通过正交实验运用二次回归方法,建立了针对干燥后耐高温原型加工参数的优化数学模型；通过Matlab软件运用遗传算法求解出了降低原型表面粗糙度的最优加工参数,为干燥后耐高温原型的加工质量提供了可靠保障。
[Abstract]:The development trend of multi-variety, small batch and rapid manufacturing requires enterprises to respond to the changes of market and customer demand quickly. With the development of rapid mould making technology and its wide application in the field of industry, especially in automobile industry, Requirements to further greatly improve the efficiency of mold manufacturing, reduce costs. In this paper, aiming at the problem of high temperature resistance prototyping in plasma spray molding technology, a direct rapid milling of clay composite material prototype is proposed to reduce the complexity of the original process and the loss of precision in the turning process. Therefore, taking the clay prototype of high temperature resistance as the research object, taking the traditional milling technology as the theoretical support, starting from the design of the clay material, the drying of the material, the processing performance of the material and its processing technological parameters, etc. A prototype composite of clay-mullite high temperature resistance was designed, and the basic theories, methods and key technologies of clay ceramic materials in the process of processing were systematically studied. The main research contents and innovative results are as follows: 1. This paper analyzes the present situation and existing problems of rapid mold making technology. Aiming at the technology of high temperature resistance prototype turning through silicon gel mold in plasma spray molding technology, the process is complicated and the precision of prototype is easily lost in the process of turning. A direct rapid prototyping process of high temperature resistance for plasma spray molding is proposed, which simplifies the process effectively. 2. The present situation of ceramic material processing technology is analyzed, and the direct processing technology of uncalcined clay material is put forward innovatively. Aiming at the problems of soft texture of unroasted clay, chip sticking knife and difficult clamping, a reasonable drying system was established by drying experiment and theoretical analysis. It was proved that the strength of clay ceramic material increased after drying. Suitable for machine tool clamping and chip non-stick knife; The machinability of clay material was studied, and the relationship between the surface quality, milling force and processing parameters of the clay prototype was analyzed, and the sintering process and shrinkage characteristics of the material were also studied. 3. Aiming at the problems of poor thermal shock resistance of pure clay materials and large shrinkage and deformation after firing, this paper further uses clay mullite composite materials to fabricate high temperature resistance prototypes. The bonding mechanism of high temperature resistant composites with polyvinyl alcohol as binder was studied. By changing the ratio of clay material, refractory mullite and water content, the effects of the above two parameters on the bending strength and sintering shrinkage of the material were studied. The results show that the flexural strength decreases with the increase of mullite and water content. The mullite content increases and the shrinkage decreases after calcination when the reasonable moisture content is determined. Finally, the reasonable mullite content and water content in the high temperature resistant composite are determined. 4. The machinability of high temperature resistant prototype composites was studied. The machinability of the composites was evaluated by bending strength (as described in 3), chip morphology and surface quality. The shape of chip is long and thin, which is not affected by processing parameters. On the basis of studying the effect of machining parameters such as spindle speed, feed speed and axial cutting depth on the surface roughness of high temperature resistant prototype after drying, the quadratic regression method was used through orthogonal experiment. The optimization mathematical model for the processing parameters of the drying high temperature tolerance prototype was established. The optimal machining parameters for reducing the surface roughness of the prototype were obtained by using genetic algorithm with Matlab software, which provided a reliable guarantee for the processing quality of the prototype after drying.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TG76;TH16

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