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71.
针对焊接油管、套管、锅炉管的焊缝在中频正火热处理时管子弯曲的现象,提出在定径段增设垂直、横向、周向可调的土耳其头机架,对焊管的弯曲实现反弯变形,从而达到在线矫直的目的。 相似文献
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K. Siegert P. Unseld J. Baur F. Kauffmann E. Arzt K.v. Niessen 《International Journal of Machine Tools and Manufacture》2006,46(11):1227-1232
High strength in combination with low density is the key features for lightweight constructions in automotive and aerospace applications. Tailor-made fiber reinforcements in light-metal matrices could help to achieve this goal. However, the integration of fibers with conventional casting-route manufacturing techniques like squeeze casting or diffusion bonding restricts the component geometry and results in elevated process cost due to long cycle times and the need of additional fiber coatings. In the center of competence for casting and thixoforging Stuttgart (CCT), new processes for manufacturing metal matrix composites are developed. Long-fiber reinforced Al–Si alloys and components are produced by thixoforging of laminates made of alternating metal matrix layers and carbon fiber fabrics. This paper illustrates the manufacturing technology and first experimental results with special focus on fiber penetration and infiltration behavior and also on the formation of fiber-matrix interface to analyze fiber damage by mechanical or chemical attack. 相似文献
74.
根据热型连铸技术原理,建立了热型连铸凝固过程一维稳态温度场的物理、数学模型。通过数值计算,得出了铸型出口温度、冷却距离、拉铸速度和喷水冷却强度等工艺参数对铸坯固液界面位置的影响。计算结果与试验结果吻合。 相似文献
75.
Energy Aspects in Drying 总被引:1,自引:0,他引:1
T. Kudra 《Drying Technology》2004,22(5):917-932
The energy performance of a dryer and a drying process is characterized by various indices such as volumetric evaporation rate, steam consumption, unit heat consumption and energy (thermal) efficiency. Of all indices, energy efficiency is the most frequently quoted, in technical specifications. A thorough analysis of available information, including the Handbook of Industrial Drying, points to the inconsistency of terminology, definition and data interpretation. Thus, reported data on energy efficiency vary significantly and frequently contradict both drying theory and industrial practice. To establish a common platform to deal with energy issues, this article provides a concise overview of the most common definitions of energy efficiency, along with a critical review of the published data. A need for energy audit and benchmarking is pointed out. To eliminate shortcomings of the energy efficiency as a lumped parameter, and to allow analysis of energy consumption over time (batch drying) or distance (continuous drying), instantaneous and cumulative indices are proposed. Using these indices, the energy performance of selected dryers is examined, and possible modifications to dryer design and operating parameters are indicated in order to reduce the overall energy consumption. 相似文献
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In this article, we study a phase field model for a two-layer fluid where the temperature dependence of both the density (buoyancy forces) and the surface tension (Marangoni effects) is considered. The phase field model consisting of a modified Navier–Stokes equation, a Cahn–Hilliard phase field equation and an energy transport equation is derived through an energetic variational procedure. An appropriate variational form and a continuous finite element method are adopted to maintain the underlying energy law to its greatest extent. A few examples for Bénard–Marangoni convection in an Acetonitrile and n-Hexane two-layer fluid system heated from above will be computed to justify our phase field model and further show the good performance of our methods. In addition, an interesting experiment will be performed to show the competition between the Marangoni effects and the buoyancy forces. 相似文献
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79.
二甘醇或乙二醇连续催化合成1,4-二氧六环 总被引:1,自引:0,他引:1
采用连续法合成1,4 二氧六环。以二甘醇为原料,温度240℃,催化剂初始浓度:硅钼酸3%,或硫酸铁3%,或硅钨酸银2%;连续补加浓度:硅钼酸1%,硫酸铁1%,硅钨酸银05%;以乙二醇为原料,温度190℃,催化剂初始浓度:硅钼酸4%,或硫酸铁35%,或硅钨酸银2%;补加浓度:硅钼酸15%,硫酸铁15%,硅钨酸银1%;控制塔顶温度为95~105℃,反应速度快,产率较高。 相似文献
80.