Simulation and prediction of flow patterns in mold filling

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Mensuration and simulation of mold filling process in semi-solid die-cast of aluminum alloy

To understand the flow trace of semi-solid slurry in mold cavity, some thermocouples were inserted in mold cavity, and the reaction timing of thermocouples showed the arrival of fluid. The filling time and rate were estimated by comparison between the experiment and calculation. The introduction of computer simulation technique based on ADSTEFAN was to predict injectionforming process and to prevent defects during trial manufacture of various parts. By comparing the formed appearance of parts in experiment and in simulation, and observing the relationship between internal defects inspected by X-ray or microscope and the flow field obtained in simulation, it was indicated that both have quite good agreement in simulation and experiment. Right predictions for cast defects resulted from mold filling can be carried out and proper direction was also proposed. The realization of numerical visualization for filling process during semi-solid die-cast process will play an important role in optimizing technology plan.     

迭代法对铸造充型数值模拟的影响

通过实际计算比较了松驰因子w和迭代次数n对铸造充型过程模拟软件中所使用的超松驰迭代法的计算影响,通过统计计算时间来比较其计算所耗时长,和与英国伯明翰大学所做的标准验证实验对比以验证其模拟精度.得出在固定的迭代次数下,松驰因子w对计算速度和计算精度有较大的影响,而迭代次数在大于临界值时则影响不大.     

Analysis of filling process of Ti6Al4V alloy melt poured in permanent mold during centrifugal casting process

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Computer simulation for centrifugal mold filling of precision titanium castings

Computer simulation codes were developed based on a proposed mathematical model for centrifugal mold filling processes and previous computer software for 3D mold filling and solidification of castings (CASM-3D for Windows). Sample simulations were implemented for mold filling processes of precision titanium castings under gravity and different centrifugal casting techniques. The computation results show that the alloy melt has a much stronger mold filling ability for thin section castings under a centrifugal force field than that only under the gravity. A "return back" mold filling manner is showed to be a reasonable technique for centrifugal casting processes, especially for thin section precision castings.     

微注塑成型中熔体充模流动的影响因素研究

针对微注塑成形中因熔体的质量小、所含的热量少及流动通道截面尺寸微小等特点所带来的不同于宏观注塑成形中的熔体流动问题及影响因素,进行了理论分析及相关试验研究。结果表明,微注塑成形中,模具温度是影响微尺度下熔体流动的重要工艺因素,且随通道截面尺寸的减小而逐渐增大;而壁面滑移对微小熔体流动行为的影响,也随通道尺寸的减小而增大。此外,模具排气、通道表面粗糙度等因素的对微注塑成形的影响也不可忽视,而表面张力等因素的影响可被忽略。     

日本铜合金金属型生产铸铁件状况

铸铁件金属型铸造技术已在工业发达国家得到应用,铜合金金属型生产铸铁件在日本得到很快发展。本文介绍了铜合金金属型的特点及其对所生产的球墨铸铁件、灰铸铁件性能的影响;比较详细地介绍了日本铜合金金属型生产铸铁件的状况。     

Low-cycle fatigue behavior of permanent mold cast and die-cast Al-Si-Cu-Mg alloys

Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys.To feature their mechanical aspect of fatigue behavior,the low-cycle fatigue behavior of permanent mold cast and die-cast Al-Si-Cu-Mg alloys at room temperature was investigated.The experimental results show that both permanent mold cast and die-cast Al-Si-Cu-Mg alloys mainly exhibit cyclic strain hardening.At the same total strain amplitude,the die-cast Al-Si-Cu-Mg alloy shows higher cyclic deformation resistance and longer fatigue life than does the permanent mold cast Al-Si-Cu-Mg alloy.The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior,and can be described by the Basquin and Coffin-Manson equations,respectively.     

考虑压力对黏度影响的注塑填充过程数值模拟

为了研究熔体黏度模型对注塑成型数值模拟精度的影响,采用不考虑压力和考虑压力对黏度影响的WLF-Cross模型,利用Moldflow Plastics Insight软件对制品填充过程进行了数值模拟。结果表明,注射压力较高时,采用考虑压力影响的黏度模型计算得到的注射压力和熔体温度显著增加,型腔填充阻力越大,注射压力和熔体温度增加越大。     

压铸模浇注系统的优化设计

应用CAE软件对压铸件的成型过程进行模拟,根据模拟的结果,对压铸模浇注系统进行优化,改善模具的浇注系统结构,提高了压铸件品质。     

Evaluation of the effect of vacuum on mold filling in the magnesium EPC process

The combination of magnesium alloys with the expendable pattern casting (EPC) process will bring a bright future for the application of magnesium alloys. Vacuum is a pre-requisite parameter in the EPC process of magnesium alloys, because without vacuum, the fluidity of the magnesium alloy in the EPC process is too poor to fill the mold completely, especially for the thin-section castings. In this investigation, the effect of vacuum on the fluidity of AZ91 magnesium alloy has been explored. A modified model has been presented to explain the effect of vacuum on mold filling, which was verified by optical microscopy.The results obtained indicate that vacuum is the most effective parameter in improving the fluidity, the effect of vacuum on the fluidity interacting strongly with the pouring temperature and coating. Vacuum greatly changes the mass and heat transfer in the EPC process. Vacuum may not only control the profile of the metal–foam interface, which will influence the mass transfer process, but may also greatly speed up the removal rate of pattern decomposition products at the metal–coating interface. It also changes the primary heat-transfer mode to heat convention, which has a great influence on the distribution of the casting temperature field and solidification process. The microstructures of castings cast with vacuum exhibit a fine grain size and a small amount of precipitated Mg₁₇Al₁₂, but vary insignificantly with the location in the castings.     

Simulation of mold filling and solidification during centrifugal precision casting of Ti−6Al−4V alloy

A two-dimensional simulation model for melt flow and solidification in centrifugal precision casting has been developed based on experimental results on melt flow in a precision casting tree for Ti-6A1-4V alloy castparts. The amount of liquid alloy is intentionally adjusted to be less than that required for complete filling and is poured under a centrifugal force. The melt flows into mold cavities keeping contact with the vertical inside walls of the cavity in the anti-rotation side, and solidifies directionally by accumulating a solidified layer from the far end of the cavity to the gate according to the gradient of centrifugal force. The model reproduces melt flow observed in casting trials and directional solidification during centrifugal casting. In addition, it has been confirmed that the centrifugal force imposed on the melt enhances removal of defects caused by entrapment of gas bubbles or by solidification shrinkage and improves mechanical properties of the castparts. Formerly Graduate School of Iron and Steel Technology Pohang University of Science and Technology San 31 Hyoja-dong, Namku, Pohang 790-784, Korea     

轮胎模具工艺知识本体描述方法研究

阐述了轮胎模具本体知识表示方法,针对现有轮胎模具工艺知识,研究了运用本体描述工艺知识的方法,并用Web本体语言OWL(web ontology language)语言将表示出来的知识存储到OWL数据库中。通过本体描述方法,解决了现有知识表示方法在表示工艺知识对象之间复杂关系时存在的问题。     

液晶显示器后盖注射模浇注与冷却系统设计

分析了液晶显示器后盖成型工艺,在模拟流动分析的基础上,确定了注射模的浇口位置和流道系统。根据显示器后盖结构设置3个冷却水道设计方案,运用CAE技术分析比较各个方案的冷却效果和结构特点,最终优化出理想的冷却系统。     

轮胎活络模具花纹块电火花加工工艺的研究应用

结合使用L580T型轮胎放电加工机加工轮胎活络模具花纹块的生产实践,分析了电火花加工花纹块零件的工艺过程,着重分析了加工过程中粗加工、精加工、微加工阶段的峰值电流、脉冲宽度、脉冲间隔的变化规律,选择了合理的参数,总结出了应用电火花加工花纹块零件的工艺流程及工艺参数配置的方法,生产表明这种工艺满足花纹块加工精度要求。     

利用结晶器专家系统对中薄板坯连铸机参数的优化

结晶器专家系统上显示的结晶器流场分布可以直接通过镶嵌在结晶器铜板上的热电偶变化趋势来反映.通过参照结晶器专家系统研究连铸机工艺参数的调整对结晶器热电偶的影响来优化结晶器的流场,最终提高连铸坯的质量和连铸机的生产效率.     

Q370R钢制丙烯球罐现场安装及灌装工艺

依托某石化公司20万t/年多元醇项目的四台Q370R钢制3 000m3丙烯球罐,根据现场施工特点,简要分析球罐的设计选材、焊接工艺制定、焊接制造要点以及合理的灌装工艺等。该球罐焊接应按有利于减小焊接变形和残余应力的原则,采用窄焊道、薄层多道焊,严格控制线能量不超过40 kJ/cm,每一焊道宽度不大于焊心直径的四倍,每一层焊道的厚度不超过3.5 mm。焊后进行无损检测、热处理以及水压、气密质量控制,确保了焊接质量。