共查询到18条相似文献,搜索用时 187 毫秒
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消失模铸造充型过程数值模拟 总被引:3,自引:3,他引:3
运用PROCAST软件对板形铸钢件的消失模充型过程进行了数值模拟。考察了阶梯式浇注系统的充型顺序以及底注式浇注系统的充型形态,另外研究了底注式浇注系统的浇注速度对缺陷形成的影响。模拟结果表明,消失模铸造中,金属液优先从阶梯式浇注系统的上层内浇道充型,充型前沿流动紊乱,铸件容易出现气孔或夹渣;对于底注式浇注系统,充型前沿的流动相对平稳,但过快的浇注速度同样会导致气孔或夹渣缺陷。 相似文献
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吴明 《特种铸造及有色合金》2007,27(8):618-619
铸件内浇道根部易出现过热,裂纹一般产生在靠近内浇道处。要求作探伤检查的铸件设计浇注系统时应使钢液充型平稳。采用转折形内浇道,能有效地降低钢液流速,转移铸件的过热区,减少和避免铸件在内浇道附近产生裂纹缺陷。 相似文献
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通过生产实例说明缝隙式内浇道砖在顶注、中注、底注缝隙式内浇道浇注系统中应用情况。应用缝隙式内浇道砖,提高了造型效率,增加了内浇道的强度,避免了铸件冲砂、夹砂缺陷,提高了铸件质量,综合经济效益好。 相似文献
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介绍了消失模铸造浇注系统设计的原则及注意事项,利用数值模拟软件分析了消失模铸造充型过程中金属液和泡沫前沿的状态,强调了3种浇注系统以及泡塑模高度对型壁迁移的影响,提出了以下建议:对于圆筒形铸件,优先选用筒内双S形横内一体、中间直浇道的浇注系统,或者在外圆设置阶梯浇注系统;对于小件串铸和简单铸件,采用顶注式浇注系统,这样有利于避免温降难题,并且有利于减少C夹杂类冷隔缺陷;对于箱体类铸件,采用U形横浇道的阶梯式浇注系统,该浇注系统充型状态均衡度较高,金属液充型前沿的气隙区也较稳定。 相似文献
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Wei Zunjie An Geying School of Materials Science Engineering Harbin Institute of Technology Harbin P. R. China 《中国有色金属学会会刊》1998,(3)
1INTRODUCTIONDuringthefilingprocesinlostfoamproces,thevelocityandthetemperaturedistributioninmoltenmetalarediferentfromthos... 相似文献
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镁合金负压消失模铸造充型过程的研究 总被引:9,自引:4,他引:9
镁合金负压消失模铸造充型过程的直接观察实验的结果表明 ,不抽真空时 ,金属前沿呈微凸形平缓地向前推进 ;抽真空时 ,因在模样分解产物的排除方向上存在一正的压力梯度 ,金属液优先沿模样壁充填型腔使流动形态呈不规则的凹形形态。提高真空度 ,不规则的流动形态的凹度更大且充型时间明显缩短。浇注方式对流动形态和充型时间的影响不大 ,与顶注和侧注相比 ,底注时充型过程最为平稳 ,且其充型时间最长。根据试验结果 ,建立了镁合金负压消失模铸造充型过程的模型 相似文献
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The preparation process of complex thin-wall magnesium alloy castings based on numerical simulation and rapid prototyping core making method is presented in this paper. The filling and solidification processes were simulated using ProCAST to optimise the gating system. The simulation results showed that compared with bottom gating system, vertical slitting gating system equipped with a slot ingate and slag tank contributed to provide a stable filling pattern and eliminate casting porosity. Additionally, Profile Failure-based Rapid Prototyping (PFRP) technology was adopted to obtain sand cores due to its complexity. Mg-4.2Zn-1.7Ce-0.8Zr-0.2Ca-0.2Sr (wt.%) alloy was selected as the alloy material because of the excellent fluidity and flame retardancy. JMatPro was utilized to calculate thermo-physical properties of the alloy to ensure the simulation validity. Casting experiments were conducted, indicating that numerical predictions agreed well with experimental results. Sound thin-wall accessory gearbox casting was obtained based on the optimised gating system and PFRP-fabricated sand cores. 相似文献
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通过对活塞式压缩机缸体底注方式和顶注雨淋两种工艺方案的充型和凝固过程的数值模拟,揭示了缸体的液相分布和温度场分布及凝固顺序和冷铁的特殊作用,冷铁使顶注雨淋方式的下低上高的温度场分布趋势得到明显的加强,改善了缸体在凝固过程中的液相分布,改变了先中间后两头的凝固顺序,缸体从总体上形成了从下往上的有利于补缩的凝固顺序。从而得出了压缩机缸体的最佳铸造工艺方案是顶注雨淋浇注系统+硕部压力冒口+底部冷铁+阀孔冷铁+缸径冷铁(下部),并预测了压缩机缸体缩孔缩松产生的部位和大小。实际生产验证了模拟结果的正确性。 相似文献
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The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. In this study, the slot gating system is employed to improve mold filling behavior and therefore, to improve the quality of aluminum castings produced in permanent molds. An equipment as well as operation procedures for real-time X-ray radiography of molten aluminum flowing into permanent molds have been developed. Graphite molds transparent to X-rays are utilized which make it possible to observe the flow pattern through a number of vertically oriented gating systems. The investigation discovers that there are many influencing factors on the mold filling process. This paper focuses its research on some of the factors, such as the dimensions of the vertical riser and slot thickness, as well as roughness of the coating layer. The results indicate that molten metal can smoothly fill into casting cavity with a proper slot gating system. A bigger vertical riser, proper slot thickness and rougher coating can provide not only a better mold filling pattern, but also hot melt into the top of the cavity. A proper temperature gradient is obtainable, higher at the bottom and lower at the top of the casting cavity, which is in favor of feeding during casting solidification. 相似文献
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介绍了铸铁件常规浇注系统的结构形式,分析了撇渣的必要条件、充分条件以及浇注系统结构对撇渣能力的影响。最终得出如下结论:(1)浇注系统应尽可能营造层流流动或降低紊流度;(2)横浇道充满是撇渣的必要条件;(3)在进行浇注系统结构设计时,应避免内浇道设在横浇道顶面和离横浇道末端太近,直浇道中心至第1个内浇道中心的距离也不能太近;(4)增加浇注系统长度、采用多组元浇注系统以及设置直浇道窝等均有利于减小铁液紊流,从而有利于夹渣和气体与金属液分离并上浮。 相似文献
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针对煤矿运输机上联接板的结构特点及其技术要求,设计了铸件分型面、浇注系统、胃口及冷铁和熔炼参数.对铸件的浇注结果进行了分析,根据披缝厚度重新计算了浇注系统,采用断面渐变的浇道控制内浇口铁水流速,使铸件夹渣缺陷明显减少.试制的上联接板铸件通过顾客水压和加工验证,可批量稳定生产. 相似文献