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立式离心场下钛合金铸件缩孔缩松数值模拟 总被引:1,自引:1,他引:0
立式离心场下,合金熔体的临界补缩固相率随铸型转速及旋转半径的变化而变化,研究结果显示,随着铸型转速以及旋转半径的增加,临界补缩固相率逐渐增大.通过试算法建立了立式离心场下动态临界补缩固相率.同时通过数值模拟方式,研究了铸型转速、旋转半径、熔体过热度以及铸型型温对钛合金铸件缩孔、缩松的影响.结果显示,随着铸型转速和旋转半径的增加以及熔体过热度及铸型温度的升高,铸件的缩孔、缩松逐渐减少. 相似文献
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在立式离心场下和重力场下对石墨型钛合金铸件在铸造过程的充填及凝固情况进行研究.结果表明:在立式离心场下钛合金熔体的铸造性能好,其流动性和充填性得到很大改善;尤其对3 mm壁厚薄壁件,在重力场下由于充填阻力大于充填力,合金熔体无法完全充填铸型,而在离心场下可以实现全部充填,且最小壁厚可达到0.3 mm.此外,离心场下由于离心力和科氏力的共同作用,铸件的缺陷明显减少,且随铸型转速的增加而不断减小. 相似文献
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以“⊥”型和棒状试样为例,研究了反重力条件下,铸造工艺参数对ZL205A合金铸件充型性能和凝固组织的影响。结果表明,对于平均壁厚小于3 mm的薄壁铸件,由于差压铸造充型过程比低压铸造平稳,所以铸件成形更好,但无法成形尖角结构;提高浇注温度或铸型预热温度,均能使差压铸造薄壁ZL205A合金铸件的充型性能得到改善,且提高浇注温度效果更明显。与低压铸造相比,差压铸造可显著细化ZL205A合金晶粒度,适当提高浇注温度与铸型温度,均能进一步细化晶粒,且提高浇注温度使晶粒细化效果更显著。对于有一定截面厚度的ZL205A合金铸件,差压铸造时,当截面厚度超过一定量时,充型性能受铸型温度及浇注系统设计的影响较小,提高铸型温度,铸件产生孔洞类缺陷的几率显著增加。 相似文献
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应用ANSYS软件对油膜轴承衬套巴氏合金层离心铸造凝固过程温度场和应力场进行了数值模拟,分析研究了不同的浇注温度和铸型预热温度对凝固过程的影响。结果表明,随着金属液浇注温度和铸型预热温度的升高,金属液凝固速率降低,铸型内部产生的热应力增大,越靠近合金层的地方,热应力越大;铸型预热温度越高,铸型的冷却能力越差;在离心铸造凝固过程中铸型预热温度的影响比浇注温度的影响更大;分析并得出了最佳工艺参数。模拟结果与实际生产相符合。 相似文献
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立式离心场下钛合金熔体充填及凝固过程研究 总被引:2,自引:0,他引:2
研究立式离心场下不同铸造工艺参数对钛合金熔体的充填及凝固缺陷形成的影响。结果显示,立式离心场下得到的钛合金铸件质量优于重力场下的铸件。立式离心场下,合金熔体由于受离心力和科氏力的作用,沿着与旋转方向相对的型壁进行充填,且熔体的截面面积随充填长度的增加而逐渐减小,但是在内浇口处由于速度降低导致截面面积有所回升。此外,铸型的旋转方向,旋转半径及旋转速度直接影响铸件缺陷的形成。旋转方向直接影响合金熔体的充填顺序,进而影响合金熔体的凝固顺序及缺陷位置。实验结果显示,旋转半径及旋转速度的增加有利于减少铸件的缺陷体积。 相似文献
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电磁离心凝固过程熔体流动和传热的有限元数值模拟 总被引:4,自引:0,他引:4
利用电磁流体动力学有关理论,建立了电磁离心凝固过程熔体流动与热量传输的耦合分析模型,采用有限元法对电磁离心凝固过程进行了分析,得出了瞬态速度场和温度场。分析结果表明,电磁离心凝固过程中,正是由于电磁力引起的受迫对流运动,对金属熔体起电磁搅拌作用并使晶粒得到细化,从而提高铸件质量。 相似文献
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Jun Zhao Zhi-yong Zhang Shi-bing Liu Kun Shi Chun-ling Bao Zhao-sheng Ning Ping Yan Lei Wang Yan-chun Lou 《中国铸造》2020,(1):29-34
Casting technology of thin-wall TiAl alloy turbochargers was studied by investment casting and numerical simulation.Misruns and gas holes were the main defects observed in preliminary work due to the poor fluidity of alloy,and to gas entrapment.In order to eliminate these defects,cast parameters,such as centrifugal rotation rate and mould preheating temperature,were optimized by numerical simulation,meanwhile,the structure of the shell mould was optimized to improve the filling capacity of TiAl alloy.Pouring experiments were carried out by vacuum induction melting furnace equipped with a water-cooled copper crucible based on the above optimization.The quality of the TiAl alloy casting was analyzed by fluorescent penetrant inspection and X-ray detection.The results show that a centrifugal rotation rate of 200 rpm,mould preheating temperature of 600°C,shell preparation through organic fiber addition can dramatically improve the mould filling capacity,and integrated turbochargers were finally prepared. 相似文献
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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. 相似文献
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首先对汽车差速器壳进行合理的铸造工艺方案设计,然后利用华铸CAE软件对球墨铸铁差速器壳的充型及凝固过程进行数值模拟.基于模拟结果,预测和分析在此工艺方案下铸件产生缩孔的倾向和形成原因,进而提出冒口补缩系统的优化方案,成功消除了差速器壳铸造过程中产生的缩孔缺陷.结果表明:利用CAE计算机模拟技术有助于为工艺方案的评估与优化提供可靠的借鉴,缩短了产品试制周期,降低废品率,保证了铸件质量. 相似文献
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Shailesh Rao Agari P. G. Mukunda Shrikantha S. Rao K. G. Sudhakar 《JOM Journal of the Minerals, Metals and Materials Society》2011,63(5):25-29
True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without
the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces
lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the
final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The
defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion
of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken
as an experiment fluid and its performance during various rotational speeds is discussed. 相似文献
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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 相似文献
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充型形态对低压铸造薄板铸件凝固过程的影响 总被引:4,自引:0,他引:4
用低压铸造方法浇铸了壁厚为5mm和2mm的Al-4.5%Cu薄板铸件,测试了温度场,并考察了反重力铸造的两种基本充型形态-反向充填和顺序充填对铸件温度分布和铸件质量的影响。研究表明,反应充填产生的温度分布不利于铸件补缩,易产生缩松缺陷;顺序充填产生的温度分布使铸件倾向于顺序凝固,有利于得到组织致密的铸件,但易在最后凝固部位产生应力和裂纹。实际生产中可根据两种充形态下铸件的凝固特点采用合适的浇注系统 相似文献