熔融态银溶氧释放机理研究与银浇铸机设计
发布时间：2019-03-24 17:10
【摘要】：随着我国经济社会发展与工业技术进步,人民生活水平日益提高,白银的消费量逐年上升,尤其是工业用银量越来越大,对白银的生产能力和产品质量提出更高要求。但是,银的溶氧释放特性产生“银雨”现象,造成银锭生产时的喷溅损失,采用小开口立模浇铸可以削弱“银雨”现象。然而,立模狭窄的型腔增加了浇铸时引流的难度,使初级银锭的生产仍然依靠手工完成,与工业现代化大趋势格格不入。因此,为抑制“银雨”现象,研究银的溶氧释放特性具有重要的理论价值和现实意义,探索浇铸新工艺对改进银锭生产过程也十分重要。结合Ag-O相图和扩散理论,对银熔液中溶氧与释放的微观行为进行分析。熔点以后银中氧的饱和溶解度出现阶跃性增加,但这个过程在时间上不是突变的,氧的溶入过程缓慢,其释放过程则相对较快,从而引发“银雨”现象。计算溶氧临界形核半径,其值为5gm左右。通过空冷试验和水冷试验研究溶氧释放行为,探索银锭水冷浇铸新工艺,结果表明：空冷试验银锭表面气孔凹坑尺寸为1～4mm,说明溶氧在熔液中经历原子氧和分子氧——临界小气泡——大气泡的过程。水冷试验加快凝固速度,“银雨”现象被明显减弱；水冷试验得到的银锭表面与空冷试验得到的相比更加光滑,表面质量明显改善；普通水口在浇铸进行一段时间后会出现堵塞现象,它在浇铸中直接应用的可行性还需要进一步研究；模具水冷两侧温度降低效果明显,可以有效减少模具在浇铸时对环境释放的热量,降低环境温度,改善浇铸环境。利用FLUENT模拟水冷条件下熔液的冷却情况,对熔液与模具的各接触面和与空气接触面以及中心点的温度变化情况进行监测,得到了水流速在0.4m/s,0.6m/s,0.8m/s和1.0m/s下各监测面和点的温度变化情况。仿真结果表明,熔液在1.5s左右凝固完成,在10s时银锭温度降到300℃左右,该结果为银浇铸机的设计奠定一定基础。在试验研究和仿真分析的基础上,对水冷浇铸机的设计进行初步探索,提出一种设计方案。借助SolidWorks对浇铸机的主体部分进行三维建模。对分模和取锭工况进行静力学分析,模拟计算结果显示,模具支架应力属于安全范围,改进后的分模机构最大应力属于安全范围。仿真结果对后续的设计和研究具有一定的参考价值。
[Abstract]:With the development of economy and society and the progress of industrial technology, the living standard of the people is increasing day by day, the consumption of silver is increasing year by year, especially the amount of silver used in industry is increasing, so the production capacity and product quality of silver are higher and higher. However, the release characteristics of dissolved oxygen of silver produced "silver rain" phenomenon, which resulted in spatter loss in the production of silver ingot, and the phenomenon of "silver rain" could be weakened by using small opening die casting. However, the narrow cavity of the vertical mold increases the difficulty of drainage during casting, which makes the production of primary silver ingots still by hand, which is incompatible with the general trend of industrial modernization. Therefore, in order to restrain the phenomenon of "silver rain", it is of great theoretical value and practical significance to study the characteristics of dissolved oxygen release of silver. It is also very important to explore a new casting process for improving the production process of silver ingots. Based on the Ag-O phase diagram and diffusion theory, the microcosmic behavior of dissolved oxygen and release in silver melt was analyzed. The saturation solubility of oxygen in silver increases step by step after melting point, but this process is not abrupt in time, the process of oxygen dissolution is slow, and its release process is relatively fast, which leads to the phenomenon of "silver rain". The critical nucleation radius of dissolved oxygen is calculated, and its value is about 5gm. The dissolved oxygen release behavior of silver ingot was studied by air cooling test and water cooling test, and the new technology of water cooling casting of silver ingot was explored. The results show that the size of pore pit on the surface of silver ingot in air cooling test is 1? 4 mm. It shows that dissolved oxygen experiences atomic oxygen and molecular oxygen-critical small bubbles-atmospheric bubbles in the molten solution. The phenomenon of "silver rain" is obviously weakened by water cooling test, and the surface of silver ingot obtained by water cooling test is smoother than that obtained by air cooling test, and the surface quality of silver ingot is obviously improved. The common nozzle will be blocked after casting for a period of time, and the feasibility of its direct application in casting needs to be further studied. It can effectively reduce the heat released by the mould to the environment, reduce the ambient temperature and improve the casting environment. Using FLUENT to simulate the cooling condition of molten liquid under water cooling condition, the temperature variation of each contact surface, air contact surface and center point of molten liquid with air and air is monitored. The water flow rate is 0.4 m / s, 0.6 m / s, and the water flow rate is 0. 4 m / s and 0. 6 m / s, respectively. The temperature variation of each monitoring surface and point under 0.8m/s and 1.0m/s. The simulation results show that the molten liquid solidifies at about 1.5s and the temperature of silver ingot drops to about 300 鈩，
本文编号：2446520
[Abstract]:With the development of economy and society and the progress of industrial technology, the living standard of the people is increasing day by day, the consumption of silver is increasing year by year, especially the amount of silver used in industry is increasing, so the production capacity and product quality of silver are higher and higher. However, the release characteristics of dissolved oxygen of silver produced "silver rain" phenomenon, which resulted in spatter loss in the production of silver ingot, and the phenomenon of "silver rain" could be weakened by using small opening die casting. However, the narrow cavity of the vertical mold increases the difficulty of drainage during casting, which makes the production of primary silver ingots still by hand, which is incompatible with the general trend of industrial modernization. Therefore, in order to restrain the phenomenon of "silver rain", it is of great theoretical value and practical significance to study the characteristics of dissolved oxygen release of silver. It is also very important to explore a new casting process for improving the production process of silver ingots. Based on the Ag-O phase diagram and diffusion theory, the microcosmic behavior of dissolved oxygen and release in silver melt was analyzed. The saturation solubility of oxygen in silver increases step by step after melting point, but this process is not abrupt in time, the process of oxygen dissolution is slow, and its release process is relatively fast, which leads to the phenomenon of "silver rain". The critical nucleation radius of dissolved oxygen is calculated, and its value is about 5gm. The dissolved oxygen release behavior of silver ingot was studied by air cooling test and water cooling test, and the new technology of water cooling casting of silver ingot was explored. The results show that the size of pore pit on the surface of silver ingot in air cooling test is 1? 4 mm. It shows that dissolved oxygen experiences atomic oxygen and molecular oxygen-critical small bubbles-atmospheric bubbles in the molten solution. The phenomenon of "silver rain" is obviously weakened by water cooling test, and the surface of silver ingot obtained by water cooling test is smoother than that obtained by air cooling test, and the surface quality of silver ingot is obviously improved. The common nozzle will be blocked after casting for a period of time, and the feasibility of its direct application in casting needs to be further studied. It can effectively reduce the heat released by the mould to the environment, reduce the ambient temperature and improve the casting environment. Using FLUENT to simulate the cooling condition of molten liquid under water cooling condition, the temperature variation of each contact surface, air contact surface and center point of molten liquid with air and air is monitored. The water flow rate is 0.4 m / s, 0.6 m / s, and the water flow rate is 0. 4 m / s and 0. 6 m / s, respectively. The temperature variation of each monitoring surface and point under 0.8m/s and 1.0m/s. The simulation results show that the molten liquid solidifies at about 1.5s and the temperature of silver ingot drops to about 300 鈩，
本文编号：2446520
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