碳酸钾水溶型芯的微滴喷射成形工艺研究

发布时间：2018-10-04 18:18

【摘要】：水溶型芯以其高效水溶溃散性能和优异环境友好特性在带有复杂内腔及弯曲孔道的铝合金铸件中有着广泛的应用。传统的成型方法,在型芯制备过程中都需要采用制芯模具,这使得制芯过程复杂、制造周期长等制约水溶型芯的发展。无模化快速成形技术因其设计和制造一体化,成形过程柔性化、主体化和多样化等优势在铸造领域取得了快速发展。因此,本文采用快速成型方法中的微滴喷射成型技术,以碳酸钾溶液为粘结剂,宝珠砂作为成形粉末,系统的研究了成型工艺过程各参数及后处理工序对碳酸钾水溶型芯性能的影响,以期获得高强度、水溶性好的水溶型芯。本文的主要内容如下:1)采用Flow-3D数值模拟的方法,研究了不同浓度的碳酸钾溶液在成形粉末多孔介质中的渗透深度,为确定铺粉层厚提供依据。研究结果确定铺粉层厚为0.035cm。2)成形工艺参数对型芯的性能有重要影响。本研究采用单因素变量法分别研究碳酸钾溶液浓度、不同加热温度和添加剂含量对微滴喷射成形碳酸钾水溶型芯初始抗拉强度的影响。研究结果表明,微滴喷射成形碳酸钾水溶型芯的初始抗拉强度,随着碳酸钾溶液浓度的增加先增大后减小,随着初始加热温度的升高也是先增大后减小,随着添加剂含量的增加而降低。3)后处理工序可增强水溶型芯的强度。本研究探究了浸润溶液浓度、浸润前和浸润后烧结温度、保温时间对型芯抗拉强度的影响规律。研究结果表明,添加了膨润土的初始型芯经烧结后可以浸润,且浸润溶液浓度为50%时,获得的型芯的强度较好;浸润后不同烧结温度下的不同保温时间对型芯抗拉强度的影响规律不同,不仅粘结剂溶液的浓度对其结晶形貌有影响,不同烧结温度、保温时间也会对结晶形貌产生影响,并影响着型芯的断裂方式和断口形貌。经过后处理的水溶型芯的抗拉强度可达2MPa以上。4)对成形后水溶型芯的水溶溃散性进行研究。研究结果表明,采用微滴喷射成形及后处理工序得到的水溶型芯的溃散性能优异,可用于复杂结构铝合金铸件的浇注。
[Abstract]:Water soluble core has been widely used in aluminum alloy castings with complex cavities and curved channels because of its high efficiency water solution collapsibility and excellent environmental friendliness. Traditional molding methods require core-making mould in the process of core preparation, which makes the core-making process complex and the manufacturing cycle long, which restricts the development of water-soluble core. Because of its advantages of integration of design and manufacture, flexibility of forming process, mainstay and diversification, mouldless rapid prototyping technology has made rapid development in the field of casting. Therefore, in this paper, the micro-droplet spray molding technology in the rapid prototyping method is used, the potassium carbonate solution is used as the binder, and the pearl sand is used as the forming powder. The effects of the parameters of the molding process and the post-treatment process on the properties of the water-soluble core of potassium carbonate were studied systematically in order to obtain the water-soluble core with high strength and good water solubility. The main contents of this paper are as follows: (1) the permeation depth of different concentrations of potassium carbonate solution in powder porous media is studied by Flow-3D numerical simulation, which provides a basis for determining the thickness of powder layer. The results show that the thickness of the powder layer is 0.035cm.2) forming process parameters have an important effect on the properties of the core. The effects of concentration of potassium carbonate solution, heating temperature and additive content on the initial tensile strength of water-soluble potassium carbonate core were studied by single factor variable method. The results show that the initial tensile strength of micro-droplet spray forming potassium carbonate water-soluble core increases first and then decreases with the increase of the concentration of potassium carbonate solution, and then decreases with the increase of initial heating temperature. With the increase of additive content, the strength of water-soluble core can be enhanced. The effects of the concentration of soakage solution, sintering temperature before and after soaking and holding time on the tensile strength of the core were investigated. The results show that the initial core with bentonite can be sintered and the strength of the core is better when the concentration of soaking solution is 50. The effect of different sintering time on the tensile strength of the core is different, not only the concentration of the binder solution has an effect on the crystalline morphology, but also the sintering temperature and the holding time have an effect on the crystalline morphology. The fracture mode and fracture morphology of the core are also affected. After treatment, the tensile strength of the water-soluble core can reach 2MPa above 4. 4) the water-soluble collapsibility of the formed water-soluble core is studied. The results show that the water-soluble core obtained by micro-droplet spray forming and post-treatment has excellent collapsibility and can be used for casting of aluminum alloy with complex structure.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG242.7

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