摘要
随着我国汽车工业的飞速发展,截止目前我国汽车的产销量已经跃居世界第一位,汽车的能耗越来越引起人们的高度重视。伴随着现代汽车轻量化、节能环保要求的不断提高,铝合金铸件在汽车工业中所占比重日益增大,同时也助推了铝合金的特种铸造成形工艺的快速发展。低压铸造作为铸造成型的工艺之一也得到了迅速的普及与推广。
与传统重力铸造工艺相比,低压铸造工艺有着十分明显的优势,可以制造出比传统工艺质量更好的铸件。可以采用带有冷却系统的模具,通过对模具温度场的控制,可以实现铸件的顺序凝固,并且铸件直接从底部进行浇注和补缩,因此可以不用冒口,铸件的工艺出品率非常高(一般在90%以上);由于铸件是在大约3个大气压力作用下充填模具型腔,因此可得到更加致密的铸件组织,尺寸精度和表面光洁度很好,也可以采用砂芯来制造出结构复杂的缸体、缸盖类铸件。
采用低压铸造工艺生产出的铸件,具有良好的力学性能,已经引起铸造工作者的广泛关注,汽车铝合金轮毂大多数都是采取低压铸造工艺。低压铸造工艺目前在日本应用十分广泛,近年来伴随着中国汽车工业的迅猛发展,国外低压设备制造商也非常关注中国这块“市场大蛋糕”,国际间技术合作与交流的更加紧密,因此,我国低压铸造技术也有了很大的提升。
本文首先对低压铸造工艺存在的问题进行了系统的分析,从而确定了影响铸件成型工艺和铸件质量的关键参数,并且从控制的角度来诠释了铸件成型与凝固的过程。
其次,设计了气体加压控制方案,并对低压加压系统进行分析,总结了影响液面加压曲线的因素,从而确定了模糊PID的控制方案。
最后,根据本人所在公司的生产实践,不断地优化了设计。从而确认采用PLC为控制手段,结合模糊PID的控制理论对低压液面加压系统进行的研究,是具有一定的理论与实践的意义。
With the rapid development of China's automobile industry, Up to now China's auto output and sales volume has reached first in the world. Energy consumption of the car more and more aroused great attention. With the lightweight, energy-saving & environmental protection requirements continue to increase, Aluminum alloy castings in the automotive industry is increasing the proportion, but also boost the special aluminum alloy casting forming process of rapid development. Low-pressure casting process as forming of one casting has also been rapidly gaining popularity and promotion. Compared with the traditional gravity casting, low pressure casting process has a very special advantage. You can create a better quality than the traditional casting process. Cooling system can be used with the mold. The mold temperature through the control of casting solidification can be achieved. And casting and casting directly from the bottom feeding, the riser isn’t used, the casting process produced a very high rate (generally 90% or more). As the three KG pressure of casting is filling the mold cavity under pressure, so the available castings more compact structure, good dimensional accuracy and surface finish can also be used to create a sand core complex structure of the cylinder block, cylinder head type castings. Low-pressure casting process to produce castings with good mechanical properties, has attracted wide attention foundry workers, the majority of car alloy wheels are taking low-pressure casting process. Low-pressure casting process is widely used at present in Japan in recent years, along with the rapid development of China's automobile industry. The foreign manufacturer of low pressure equipment is also very concerned about China as "the market of big cake", the international technical cooperation and exchange more closely. Therefore, China's low-pressure casting technology has been greatly improved
First, the paper with low-pressure casting process problems in a systematic analysis to determine the impact of the quality of casting molding and casting a critical parameter, from the control point of view to explain the casting molding and solidification process.
Secondly, the design of the gas pressure control programs, and low pressure systems analysis, summarized the factors that affect the surface pressure curve to determine the fuzzy PID control scheme.
Finally, the production company where I practice, continue to optimize the design. So, confirming the use of PLC as a means of control, combined with the theory of fuzzy PID control system for low liquid pressure studies, is a certain amount of theoretical and practical significance.
引文
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