Advanced Materials Research Vol. 744

Abstract: For marine engine, the quality of the crankshaft is a decisive factor for its mechanical life. In the manufacturing processes of semi-built-up marine crankshaft, as the final process, finish machining of the entirety is vital to the machining accuracy. Applying finite element method, the traditional way for fixturing is analyzed and the problem of machining deformation because of poor rigid and great weight is pointed out. In addition, a new fixturing method is put forward according the structure characters of crankshaft, which provides a technical support for practical machining and theoretical principle of fixturing method for extreme manufacturing. Moreover, a further research direction to increase the fixturing and adjustment efficiency is proposed.

Abstract: This paper analyzes the influence of lubricating oil film of the low-speed and heavy-load sliding bearing on a variety of factors. It introduces the operation of Bearing for lubricating oil film in monitoring method, common fault causes and treatment measures. Finally, the bearing cooling system structure is discussed, providing reference for practical engineering application. There are many reasons to cause the failure of the bearing lubrication such as bearing assembly defects, the error of size and cooling system problems. By detecting and contrast parameters, this study analyze the determine data and correct the fault. Through the use of reasonable structure of the oil tank and cooling water channel, we can improve the lubrication performance, and extend the bearing life. This paper analyzes the factors restricting the low speed and high load sliding bearing lubricant film, and solves the actual bearing lubrication problem.

Abstract: Several models for calculating the heat transfer coefficient of wheel rims of large capacity steam turbines are presented. Taking a certain 600MW supercritical turbine rotor as an example, the heat transfer coefficient of wheel rim under cold start-up are analyzed and calculated, according to the and comparison, and the quantitative calculation results are given The results show that the heat transfer coefficient of rotor rims obtained by Sarkar method is close to the heat transfer coefficient obtained by a research institute based on a rib heat transfer model. In finite element analyses, the calculation results by mentioned method could provide the heat transfer boundary condition of temperature and thermal stress field calculations of supercritical and ultra-supercritical steam turbine rotors.

Abstract: Steam turbine units are required to start up and shut down as fast as possible to improve economy and load-response ability of the units under the qualification of safety. it is important to monitor and control thermal state in turbine during operation, especially during the process of start-up and shutdown. Thermal stresses in turbine rotor in thermal power plants are the limiting factors for rapid startup, shutdown or load change. In this paper the online calculation models of temperature and thermal stress for a two-dimensional axis-symmetric object are obtained after disposing of the nonlinear factor such as temperature-dependent properties by a transformation. The model gained can be used to analyze thermal states in thick-walled components, monitoring and control online.

Abstract: In this paper a lifting device for quickly servicing top beam of the great mining height support on fully mechanized coal mining face is introduced and the technical characteristic,working theory,application effect in mine of the lifting device are expounded. This lifting device makes the safety and efficiency of supports maintenance improved greatly. The lifting device occupies small space and has simple structure and doesnt influence the motion and operation of supports. Labor-saving,time-saving ,safe and reliable are also one of the features.This lifting device can be used and the lifter winch be dismantled at any time and needs less maintenance personnel.The using of this device achieves the goal of senting maintenance personnel or accessories to the working height quickly,safely and accurately and accelerates the development of working face.

Abstract: In order to research the leakage mechanism and influence factors of the hydraulic rock drill, the mathematical model of the leakage is established, and combined with the structure and working principle of the hydraulic rock drill, the impact mechanism dynamics simulation model is built by the AMESim software. Through the analysis of the leakage model, the influence of differential pressure, sealing length and clearance on the leakage is got, the simulation analysis results are consistent with the mathematical model conclusions, and the results have important guiding significance on the clearance selection and the effective control of leakage of the impact mechanism.

Abstract: In this paper,the importance of controlling side fall in great mining height coal face is introduced,and the stability of great mining height coal seam,the types and characteristics of sprag units are researched. Through the study this paper designs and confirms the sprag units structure which is fit for the great mining height hydraulic supports well. Hydraulic support sprag unit structure mainly have two types: simple aticulated type and four-bar linkage type.By the analysis and comparision of the characteristic of retractable type and folding type, the folding sprag units which has better integral rigidity is selected.It also provides the methods and experience for the the design of hydraulic support ,especially for the sprag units design of great height hydraulic supports.

Abstract: Analyzed the main factors of affecting hydraulic support stability, this paper analyses anti-topple and antiskid technology to apply to inclined angle 15~33°and compatible supports ZF4200/16/26. Through the practical application in shanjia mine, it can meet large inclined angle mine demands. The follows were studied that can influence the stability of support in large inclined angle coal seam. Every roof situation in the direction of large inclined angle suffering different stress lead to different caving property, and the roof motivation can affect other supports strained condition and stability. Caving mechanism behind the caving coal support suffer downward force, and the force is put on caving shield and tail beam, so it makes supports generate angle of bank. The support would lose its stability with working face processing and supports advancing for descending support and losing point of support.

Abstract: This paper mainly analyzes suite of hydraulic support technical parameters and structure design applied to fully-mechanized faces withdrawal, according to coordinating with auxiliary roadway multi-channel crafts, which achieves fully mechanized support in the fully-mechanized face in Inner Mongolia and Shenmu. It provides automatic essential equipment for fully-mechanized face withdrawal. Using computer technology to study the suite of hydraulic support: Using designed analysis software optimizes and designs the support the structure parameter to achieve the optional performance and enhance stability, supporting performance and anti-twisting property. Experiment of prototype was produced to simulate the moving process exactly by virtual prototype technology and three-dimensional entity design software, optimizing the original project. Operating condition of supports in the underground mine was simulated for overall strength analysis with virtual prototype technology.

Abstract: Analyzed the trend of the development of hydraulic powered support and column, this paper designs a column strength test bench with 20000KN working resistance which combined with the new release of GB25974.2-2010 for coal mine hydraulic support and jack technical conditions of Part 2 standard requirements. Through the practical application, it turned out that the test bench has reasonable structure, stable performance and it can meet all of the following Ф630 bore hydraulic support column factory test requirements. The trend of the mine-used hydraulic support column and the performed new criterion demands manufacturers to enhance the ability of test equipment. In this situation, the 20000KN column strength test bench our company designed and manufactured not only do the loading test, but also apply external load at columns by simulating the actual working conditions, which is essential to Inspection and testing of dual-extension hydraulic columns middle cylinder strength.