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Separation mechanism for double cylinder with shrink fitting system used for ceramics conveying rollers
Wenbin LI, Hiromasa SAKAI, Shota HARADA, Yasushi TAKASE, Nao-Aki NODA
Front Mech Eng. 2011, 6 (3): 277-286.
https://doi.org/10.1007/s11465-011-0234-y
Steel conveying rollers used in hot rolling mills must be exchanged frequently at great cost because hot conveyed strips induce wear and deterioration on the surface of roller in short periods. In previous studies, new roller structure was considered which has a ceramics sleeve connected with two steel shafts at both ends by shrink fitting. Here, although the ceramics sleeve can be used for many years, the steel shafts sometimes have to be exchanged for maintenance and reconstruction under the corrosive atmosphere. Since the thermal expansion coefficient of steel is about five times larger than that of ceramics, it is necessary to investigate how to separate the shrink fitting system by heating outside of sleeve and cooling inside of the shaft. Although how to separate the real roller has been discussed in the previous study, the separation mechanism has not been clarified yet. Therefore, in this study, several types of more fundamental models are investigated to understand the separation mechanism of real roller by the application of the finite element method. The results may be useful for designs of new rollers.
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Refined analysis of axi-symmetric circular cylinder in the axial magnetic field without ad hoc assumption
Baosheng ZHAO, Yang GAO, Yingtao ZHAO, Dechen ZHANG
Front Mech Eng. 2011, 6 (3): 318-323.
https://doi.org/10.1007/s11465-011-0232-0
The refined theory for axi-symmetric magnetoelastic circular cylinder is deduced systematically and directly from linear magnetoelasticity theory. Based on the general solution of magnetoelastic equation and the Lur’e method, the refined theory yields the solutions for magnetoelastic circular cylinder without ad hoc assumptions. On the basis of the refined theory developed in the present study, solutions are obtained for magnetoelastic circular cylinder with homogeneous and non-homogenous boundary conditions, respectively. For the circular cylinder with homogeneous boundary conditions, the refined theory provides exact solutions that satisfy all of the governing equations. The exact solutions can be divided into three parts: the 2-orders equation, the transcendental equation, and the magnetic equation. In the case of non-homogenous boundary conditions, the approximate governing equations are accurate up to the high-order terms with respect to cylinder radius.
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Modelling and diagnostics of multiple cathodes plasma torch system for plasma spraying
Kirsten BOBZIN, Nazlim BAGCIVAN, Lidong ZHAO, Ivica PETKOVIC, Jochen SCHEIN, Karsten HARTZ-BEHREND, Stefan KIRNER, José-Luis MARQUéS, Günter FORSTER
Front Mech Eng. 2011, 6 (3): 324-331.
https://doi.org/10.1007/s11465-011-0125-2
Usage of a multiple-arcs system has significantly improved process stability and coating properties in air plasma spraying. However, there are still demands on understanding and controlling the physical process to determine process conditions for reproducible coating quality and homogeneity of coating microstructure. The main goal of this work is the application of numerical simulation for the prediction of the temperature profiles at the torch outlet for real process conditions. Behaviour of the gas flow and electric arcs were described in a three-dimensional numerical model. The calculated results showed the characteristic triangular temperature distribution at the torch nozzle outlet caused by three electric arcs. These results were compared with experimentally determined temperature distributions, which were obtained with specially developed computed tomography equipment for reconstructing the emissivity and temperature distribution of the plasma jet close to the torch exit. The calculated results related to temperature values and contours were verified for the most process parameters with experimental ones.
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Influence of boundary conditions and turntable speeds on the stability of hydrostatic oil cavity
Zhaomiao LIU, Chengyin ZHANG, Feng SHEN
Front Mech Eng. 2011, 6 (3): 359-368.
https://doi.org/10.1007/s11465-011-0222-2
The flow, bearing, and carrying capacity of the cycloidal hydrostatic oil cavity in hydrostatic turntable systems are numerically simulated, considering the rotation speeds of a turntable from 0 to 5 m/s and different boundary conditions. The vortex effect is weakened, and the stability of the oil cavity is enhanced with the increase in lubricant viscosity. However, the increase in inlet speed, depth, and inlet radius of the oil cavity causes the vortex effect to increase and the stability of oil cavity to reduce. With the increase in the oil film thickness, the carrying capacity of the oil cavity diminishes. The oil cavity pressure increases along the direction of the motion of the turntable; it is distributed unevenly because of the rotation of the turntable. With the increase in turntable speed, the location and size of the vortex scope in the oil cavity flow field and the strength of the vortex near the entrance gradually weaken and move away from the entry. The distribution of pressure is determined by the locations of the vortex. When the vortex is close to the wall, the wall pressure increases at its location. Otherwise, the wall pressure decreases first and then increases after the center of the vortex.
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Drive system design and error analysis of the 6 degrees of freedom segment erector of shield tunneling machine
Hu SHI, Guofang GONG, Huayong YANG
Front Mech Eng. 2011, 6 (3): 369-376.
https://doi.org/10.1007/s11465-011-0223-1
Focusing on a segment erector of a shield-tunneling machine developed with 6 degrees of freedom (DOF) and controlled by electro-hydraulic proportional systems, the kinematics of the segment erection process is presented. The perturbation method in the error analysis is introduced to establish the position and attitude error model, considering a number of factors such as the hydraulic drive, control accuracy, and tolerance in manufacturing and assembly. Dynamic simulations are carried out to obtain the controlling precision of electrohydraulic drive systems. Formulas for calculating the position and attitude error of the grip hand of the segment erector are derived. The calculation results verify the practicality and effectiveness of the error analysis, providing a foundation for practical designing, manufacturing, and assembling of the segment of the erecting mechanism.
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17 articles
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