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排序方式: 共有372条查询结果,搜索用时 15 毫秒
51.
介绍了粗糙度的定义,指出球墨铸铁件在软氮化后进行珩磨加工时形成的石墨坑对表面质量的影响,并提出相应的表面质量控制方法。 相似文献
52.
利用华铸CAE/Inte-CAST8.0软件对大型铸钢件进行了温度场的凝固模拟,预测了缩孔、缩松缺陷产生的部位,并且分析了缺陷产生的原因,在此基础上对其铸造工艺进行了优化。优化后的模拟结果表明:合理设置保温冒口、冷铁的大小和位置,可以保证铸件顺序凝固,并且延长金属液的有效补缩距离,获得符合国际标准的大型铸钢件。 相似文献
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The distribution of a magnetic field over an inductor used for sheet castings has been investigated experimentally. With an increase in height from the surface, the magnetic field density decreases according to the exponential law. In the transverse direction, the magnetic field density is approximately uniform except near the edges. The magnetic field density is direct proportional to the number of turns multiplied by the current in amperes. Ferromagnetic material in the upper mould can enhance the magnetic field density. Under the electromagnetic force, the mould-filling process of sheet casings has been studied by physical simulation method. The difference in filling capability between gravity casting and travelling magnetic field casting has been studied. The electromagnetic force can enhance the filling process, but it also brings a problem. With an increase in the magnetic field density, the surface quality of the aluminum alloy sheet castings becomes poor. The reason is discussed. 相似文献
56.
介绍了机床铸件精度保持的三要素:耐磨性、刚性、减震性.与传统的机床铸件材料相比较,蠕墨铸铁能最好地满足这三要素的要求,因而可以成为机床重要铸件的首选材料,其优良的综合力学性能为铸件减薄壁厚、减轻质量提供了材质保障.分析了蠕铁+灰铁双层铸造失败的原因;指出,蠕墨铸铁在机床铸件上应用能否得到推广,关键足机床设计人员对蠕铁材料优越性的了解和选用. 相似文献
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N. A. El-Mahallawy M. A. Taha A. K. El-Kharbotly A. F. Youssef W. Reif 《International Journal of Cast Metals Research》2013,26(3):185-190
A technique for the preparation of an MMC using centrifugal casting has been developed and tested for its feasibility in preparing Al-12Si-2Mg/Al2O3- particulate composites. The process is evaluated by observing the structure, measuring the homogeneity in the distribution of the ceramic particles, the porosity type and distribution, and by analysing the metal/ceramic interface for possible reactions.The different processing conditions applied are: rotational frequency 16, 22.7 and 33.3 Hz (960, 1360 and 2000 rpm), Al2O3 particle size 30, 47, 60 and 89 μn, melt superheat 20, 100 and 150°C, specimen radius of rotation from 145 to 180 mm.Because the ceramic particles are close packed, a uniform particle distribution with no agglomeration is obtained, and the interparticle distance depends only on the alumina particle size. The metal/ceramic interface was sharp with no reaction. Microporosity is observed in some locations due to incomplete infiltration between the alumina particles. Increasing rotational speed, particle size, superheat, and radius of rotation help to decrease the microporosity. The macrostructure along the composite length showed columnar grains followed by equiaxed grains. The type and size of the structure depend mainly on the composition of the matrix and not on the presence of the alumina particles. 相似文献
59.
H. Soda G. Motoyasu F. Chabchoub H. Hu A. Mclean 《International Journal of Cast Metals Research》2013,26(4):225-230
AbstractTin wires of 2 mm dia have been cast by the horizontal OCC process at speeds between 0.02 m/min and 4.2 m/min. It was found that unlike the casting of larger diameter rods, it was possible to continue casting, even if the solid-liquid interface existed outside the mould. If the mould exit temperature and the mould-cooler distance were maintained at 267°C and 2 mm respectively, the solid-liquid interface was located at the mould exit when the casting speed was 0.35 m/mln. However, when the casting speed exceeded about 1.2 m/min, the cast surface of the wire deteriorated and exhibited a matted appearance due to the formation of ridges. With a casting speed of 4.2 m/min, the solid-liquid interface location was estimated to be about 4 mm outside the mould. A calculated temperature distribution within the solidifying strand revealed that the solid-liquid interface entered the cooling water when the casting speed was 1.2 m/min. Thus, in order to obtain a cast wire with a high surface finish, the strand should be solidified outside the cooling water. Casting parameter values corresponding to the condition where the solid-liquid interface reaches the mould exit were considered to be critical co-ordinates for runout (breakout). When the solid-liquid interface is located between the mould and the cooling water, tight control of the casting process, and in particular control of the metal head, is essential in order to avoid dimensional instability and runout of the liquid metal. 相似文献
60.
Laurentiu Nastac Shian Jia Mihaela N. Nastac Robert Wood 《International Journal of Cast Metals Research》2013,26(4):194-201
Modelling of gas evolution during sand-mould castings is one of the most important technical and environmental issues facing the metal casting industry. The current effort focused on developing the capability of numerically predicting the gas evolution for the furan binder-silica sand system. Specifically, the decomposition of furan was experimentally analyzed and then predicted based upon the work developed in the current project. This methodology can be easily implemented into existing commercial casting codes. A parametric study was also performed for steel 4340 and aluminium A356 cylinders (D100 × H200 m) and bars (H50 mm × W50 mm × L250 mm) cast into silica sand moulds (furan binder) of 50-mm mould wall thickness to investigate the effects of superheat and heating/cooling conditions of the mould on the gas evolution. Such information would enable more technically and environmentally friendly decisions to be made concerning the process design used to make a given casting. 相似文献