铝合金活塞缺陷的数值模拟研究
发布时间：2018-07-29 20:08
【摘要】：铸造是液态金属先充填铸件的型腔,然后在其中受冷凝固的过程。充型过程和凝固过程对最后的铸件质量好坏起到至关重要的作用,对缩孔、缩松、气孔、夹渣等铸造缺陷的产生有直接影响。因此,利用铸造CAE软件模拟充型和凝固过程,探究液态金属充填型腔的充型顺序以及充型过程中的温度变化,探究凝固过程中的凝固次序以及温度场分布,分析缺陷的形成机理及分布规律,进而优化工艺参数、改进铸造工艺,降低铸件缺陷率,提高生产效率。本课题以金属型铸造水泵活塞为凝固模拟研究对象,通过华铸CAE软件进行数值模拟,分析缩孔、缩松的分布及参数改变对其影响,寻找最佳的浇冒口系统、浇注温度及模具温度；以压铸割草机活塞为充型模拟研究对象,通过Flow-3D软件进行数值模拟,分析气孔、夹渣的形成及分布机理,寻找最佳充型速度参数。针对水泵活塞的结构特点,设计出合适的浇注系统、顶冒口及侧冒口的尺寸,模拟试加冒口、底注式工艺,改进顶冒口及侧冒口的尺寸,将浇注方式由底注改为中注,模拟改进冒口、中注式工艺,由模拟结果分析得到最优的浇冒口系统为改进冒口、中注式工艺。在最优的浇冒口系统基础上,模具预热温度选择为200℃,浇注温度选取在700-800℃之间,模拟缩孔、缩松的分布,由模拟结果分析得到最佳的浇注温度为780℃；浇注温度选择为780℃,模具预热温度选取在160-260℃之间,模拟缩孔、缩松的分布,由模拟结果分析得到最佳的模具温度为200℃。应用改进冒口、中注式工艺,选择浇注温度780℃、模具温度200℃,以此模拟得出的最优工艺参数进行生产,最终得到的铸件表面质量好、内部无孔洞,缩孔、缩松缺陷率始终在5%以内,达到了预期目标。针对割草机活塞的结构特点,设定浇注温度为680℃,模具预热温度为200℃,充型速度选取在50-500cm/s之间,模拟得到不同充型速度下的夹渣量和卷气体积变化曲线。通过模拟结果分析,充型速度越小,充型时间越长,高温合金液与铸型反应生产的氧化物越多,更重要的是,夹渣不能及时顺着液流排到渣包,所以铸件表面的夹渣量越多；充型速度越大,合金液填充型腔时卷入的气体越多,碰撞上面型壁后回落时包裹的气体越多,并且不能从排气槽及时排出,所以铸件内部出现的气孔越多。试验选择性地做了充型速度50cm/s、200cm/s、400cm/s条件下的压铸实验,从得到的活塞可以发现,充型速度从50cm/s变化到200cm/s时,夹渣缺陷大部分被消除,充型速度从400cm/s变化到200cm/s时,气孔缺陷减少了很多,与模拟结果得到的变化趋势一致。
[Abstract]:Casting is a process in which liquid metal fills the cavity of the casting and is then solidified by cold. The filling process and solidification process play an important role in the final casting quality, and have a direct impact on the production of casting defects such as shrinkage, porosity, slag inclusion and so on. Therefore, the mold filling and solidification process are simulated by casting CAE software, and the filling order of liquid metal filling cavity and the temperature change in the filling process are explored, and the solidification sequence and temperature field distribution in the solidification process are also investigated. The forming mechanism and distribution law of defects are analyzed, and the process parameters are optimized, the casting process is improved, the defect rate of casting is reduced, and the production efficiency is improved. This subject takes the metal mold casting pump piston as the solidification simulation object, carries on the numerical simulation through the Hua casting CAE software, analyzes the shrinkage hole, the shrinkage porosity distribution and the parameter change to it, looks for the best pouring riser system. The pouring temperature and mold temperature, the piston of the die casting mower as the model filling simulation object, the numerical simulation by Flow-3D software, the analysis of the formation and distribution mechanism of the air hole and the slag inclusion, and the finding of the best filling speed parameter. According to the structural characteristics of pump piston, the proper gating system, the size of top riser and side riser, the simulated trial riser, the bottom casting process, the improvement of the size of the top riser and the side riser are designed, and the pouring mode is changed from the bottom injection to the middle injection. The simulation results show that the optimal riser system is the improved riser and the middle injection process. On the basis of the optimum pouring riser system, the preheating temperature of the die is 200 鈩，
本文编号：2153859
[Abstract]:Casting is a process in which liquid metal fills the cavity of the casting and is then solidified by cold. The filling process and solidification process play an important role in the final casting quality, and have a direct impact on the production of casting defects such as shrinkage, porosity, slag inclusion and so on. Therefore, the mold filling and solidification process are simulated by casting CAE software, and the filling order of liquid metal filling cavity and the temperature change in the filling process are explored, and the solidification sequence and temperature field distribution in the solidification process are also investigated. The forming mechanism and distribution law of defects are analyzed, and the process parameters are optimized, the casting process is improved, the defect rate of casting is reduced, and the production efficiency is improved. This subject takes the metal mold casting pump piston as the solidification simulation object, carries on the numerical simulation through the Hua casting CAE software, analyzes the shrinkage hole, the shrinkage porosity distribution and the parameter change to it, looks for the best pouring riser system. The pouring temperature and mold temperature, the piston of the die casting mower as the model filling simulation object, the numerical simulation by Flow-3D software, the analysis of the formation and distribution mechanism of the air hole and the slag inclusion, and the finding of the best filling speed parameter. According to the structural characteristics of pump piston, the proper gating system, the size of top riser and side riser, the simulated trial riser, the bottom casting process, the improvement of the size of the top riser and the side riser are designed, and the pouring mode is changed from the bottom injection to the middle injection. The simulation results show that the optimal riser system is the improved riser and the middle injection process. On the basis of the optimum pouring riser system, the preheating temperature of the die is 200 鈩，
本文编号：2153859
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