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研究了保温冒口在有色金属铸造中的作用。结果表明:采用膨胀珍珠岩和空心微珠等材料,按三种方案配比,配以适当的干燥工艺,可以使冒口体积缩小50%,保温冒口金属的凝固时间延长1-3倍,工艺出品率提高10%-25%。 相似文献
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研究了保温冒口在有色金属铸造中的作用。结果在明:采用膨胀珍珠岩和空心微珠等材料,按三种方案配比,配以适当的干燥工艺,可以使冒口体积缩小50%,保温冒口金属的凝固时间延长1~3倍,工艺出品率提高10%~25%。 相似文献
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对大型钢锭冒口处的保温砖采用实验检测的保温砖物性参数进行数值模拟,对比了不同保温砖结构对钢锭冒口区凝固过程的影响,结果表明,轻质砖和WDS的使用能够延长冒口处钢液的凝固时间,有利于钢锭的补缩,提高钢锭质量,建议减薄粘土砖的厚度,以充分发挥轻质砖和WDS的保温作用. 相似文献
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实验证明:在正确选择冷铁尺寸和形状因素(F_(?))后,通用的冒口设计(1—β)V_1/V_c=A_r/A_c·b_r/b_c·f_■·f_h β也适用于宽结晶温度间隔合金的砂型铸件,通过对Al—4·5%Cu(ZL 203)合金板状铸件的验证:在与冷铁配合下普通冒口可保证铸件的内部质量,陶瓷棉保温冒口可比普通冒口约小4倍,铸件实收率提高约25%。最后也证实了平均温度梯度、凝固时间,补缩效能系数、凝固指数和冒口凝固时间变化率是影响宽结晶温度间隔合金铸件致密度和评定冒口有效补缩作用的重要参数。 相似文献
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介绍了基于CAE的冒口设计方法,针对传统的冒口设计方法中存在的不足,采用AnyCasting铸造模拟软件对某厂生产的挖掘机齿圈座铸钢件发热保温冒口进行模拟.根据模拟所得的铸件凝固时间直接计算冒口模数,并利用补缩液量法校核冒口体积并确定冒口的数量.生产验证表明,该工艺设计的发热保温冒口补缩效果良好与模拟结果相符,既保证铸件无缩孔缺陷,又提高了工艺出品率. 相似文献
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采用膨胀珍珠岩、空心微珠复合型保温冒口取代普通冒口,生产高锰钢挖金斗铸件。保温冒口尺寸是普通冒口三维空问尺寸的80%,冒口体积是普通冒口的1/2,工艺出品率由61.6%提高到75%,补缩效率由原来的12%提高到42.5~55%。 相似文献
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测温试验表明,冒口放在热节上,热节处的凝固时间延长80%;冒口离开热节的距离为1.68倍热节圆直径时,冒口对热节的热影响基本消失。冒口离开热节放在次热节或薄壁处,形成的接触热节可使该处凝固时间延长40.4%,有利于建立冒口—接触热节—热节—薄壁之间的动态顺序凝固条件 相似文献
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将保温和发热材料用于铸件冒口可提高工艺收得率和铸件产量,降低产品成本,并有助于产品质量的提高和节约能源。此文重点介绍英国发热保温冒口的类型及计算方法和应用实例。一、保温与发热冒口均分类: 保温与发热冒口可分为三种:发热冒口;保温冒口;发热保温冒口。 1、发热冒口:FEEDEX,此种发热套内含有铝热剂,系多孔物无纤维,发热后套内形成薄亮起隔热作用,适用于各种铸造合金。冒口有各种规格,并有粉状料,使用时加水调合可做成各种规格的冒口,混碾时间为2分钟,含水量4%、5%、9%的三种套烘干温度为 相似文献
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Murat Tiryakioğlu Ergin Tiryakioğlu John Campbell 《International Journal of Cast Metals Research》2013,26(6):371-375
Feeder models that incorporate mass transfer from feeder to casting are reviewed, and assumptions made during their development are discussed. A new approach that incorporates a superheat model from the literature is introduced. The new approach is based on the equality of solidification times of feeder and the feeder-casting combination. The superheat mode is used to adjust the solidification times of feeder and casting to account for heat transfer. 相似文献
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基于均衡凝固理论设计球墨铸铁件冒口 总被引:1,自引:0,他引:1
介绍均衡凝固的基本原理,叙述铸件结构、冒口位置和冷铁对补缩的影响。结合铸件实例,说明合理设计冒口和利用冷铁使球铁铸件实现均衡凝固,防止缩孔、缩松的工艺方法。 相似文献
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铝合金活塞铸件的温度场数值模拟研究 总被引:5,自引:4,他引:1
开发了三维温度场计算程序,模拟了活塞铸件在不同界面换热系数下的金属型凝固进程,说明界面换热系数对金属型凝固速度影响很大,可作为调节金属型凝固的控制因素。同时还对比说明了相对计算的意义。 相似文献
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分析了主滚轮传统铸造工艺的缺点,提出采用均衡凝固理论和压边浇冒口的工艺方法,防止铸件产生缩孔和缩松缺陷,效果显著。 相似文献
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Y. W. Lee E. Chang Y. S. Kuo Y. L. Lin C. H. Yeh 《International Journal of Cast Metals Research》2013,26(2):106-111
AbstractThe effect of casting geometry, together with the influence of variation of feeder-head (riser) size, on the feeding behaviour of an A206 alloy was examined by density measurement, X-ray radiography and thermal analysis. The porosity content of an end-chilled plate casting was found to increase from the chilled end to the feeder end. For thin castings, feeder-head size exerts little influence on the porosity content of a plate casting whereas the porosity content of thick plates, particularly at the feeder end, is markedly reduced by increasing feeder size. A plot of porosity content as a function of thermal gradient/solidification time (G/t) was found to be made up of two individual bands. For the same value of G/t, thin castings showed a higher porosity content. The split of the curve can be explained by the solidus velocity and the slope of the porosity content—solidification time plot. 相似文献
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Plastic deformation was newly introduced in transient liquid phase (TLP) diffusion bonding of steel sandwich panels. The effect
of plastic deformation on bonding strength was investigated through lab experiments. It was assumed that three factors, including
newly generated metal surface area, deformation heat, and lattice distortion, contribute to the acceleration of interface
atoms diffusion and increase of diffusion coefficients. A numerical model of isothermal solidification time was developed
for TLP bonding process under plastic deformation and applied to carbon steel sandwich panels bonding with copper interlayer.
A reasonable isothermal solidification time was obtained when an effective diffusion coefficient was used. Based on lab experiments,
the effects of plastic deformation on interlayer film thickness and isothermal solidification time were studied through theoretical
calculation with the new model. The evolution of interlayer film thickness indicates a good agreement between the calculation
and experimental measurement. The results show that the isothermal solidification time is obviously reduced due to the effect
of plastic deformation. Furthermore, a new steel sandwich cooling panel for heat exchanger was fabricated by TLP diffusion
bonding under 13.1% plastic deformation. The test results suggest that a steel sandwich panel of inequidistant fin structure
can provide enhanced heat transfer efficiency. 相似文献
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采用Procast软件中的Mile算法对Ag-28Cu合金连铸凝固过程中温度场的非稳态变化进行了模拟,研究了不同拉速、过热度和换热系数对温度场分布、凝固速率和凝固前沿温度梯度变化的影响。模拟结果表明:随拉速的增大,铸件中心区域的凝固速率加快,凝固前沿温度梯度变化范围减小。换热系数的改变在靠近铸件表面区域对凝固速率基本没有影响,但靠近铸件中心区域后,其凝固速率随换热系数开始大幅度增大。在整个凝固过程中,换热系数越大,凝固前沿温度梯度越大。随浇注温度的提高,其凝固速率呈振荡式增大,凝固前沿温度梯度呈振荡式减小。 相似文献