High-speed electric multiple units have numerous advantages. However, a number of critical maintenance issues arise in the operation of high-speed electric multiple units. The previous researches about rail profile design usually take only a single type of wheel profile into account, which would cause some other problems such as severe increase of hollow wear on the wheels. This study systematically investigates the influence of rail grinding on running stability and wear development in high-speed electric multiple units and designs a new rail profile as reference for grinding that takes all types of vehicle wheels running on a specific line into account, in order to design a ground rail which could match the wheel profile and thus improve the running stability of electric multiple units. All types of wheel profiles used on the Wuhan–Guangzhou railway line are taken as the design reference. A wheel–rail wear simulation program is constructed based on CONTACT numerical simulation software and SIMPACK vehicle system dynamics software. The simulation results show that both the wheel–rail contact relationship and the running stability of high-speed electric multiple units improved after rail grinding. The results of the wheel wear analysis show that when the rail is ground to the target profile, after a running mileage of 200,000 km, the wear area of the new wheel profile LMA and the greatest hollow wear wheel profile LMA-25 decreases by 1.13 mm2 and 9.86 mm2, respectively. In addition, this method can prolong the wheel reprofiling interval. For the Wuhan–Guangzhou railway line, normally the grinding interval for the tangent track and large-radius curve is 2–3 years, and for the entering and exiting tunnel sections, the grinding interval should be set for 1–2 years, which could remove the damaged layer of the rail surface and could restore the designed profile of the rail and prolong the rail service life.
By study on the current domestic cutting technics of vertical-pull glass pipe, in this paper a new and practical design of automatic cutting robot is peoposed. Its motion process is introduced on the basis of performance requirement, and then the overall structure of automatic cutting robot for vertical-pull glass pipe is designed, especially the electro-hydraulic proportional control systems for frame rotation and fuselage lifting. Meanwhile the stability and respond speed of hydraulic systems is well analyzed with matlab software. The results of open-loop bode diagram of the frame rotation system and unit step response diagram of fuselage lifting system indicate that the automatic cutting robot has excellent system stability and respond speed. It can content the requirement of position accuracy, reduce the labor intensity with high productivity and liberate the workers from wicked environment.
The hydraulic cylinder is an actuator of hydraulic lifting system in the heavy tipper, which also plays an important role in unloading. Aiming at the existing multistage hydraulic cylinder design method's insufficiency, the CAD/CAE technology is introduced into the domains of multistage hydraulic cylinder design. In this paper push-forwarding five-stage hydraulic cylinder is designed, and virtual assembly is established based on three-dimensional digital model using PRO/E sofeware. The multistage hydraulic cylinder's load-supporting characteristics are analyzed by ANSYS. The result of finite element analysis shows that the stress on the top front part of three down hydraulic cylinder is biggest, those on the trunnion and the cylinder's bottom are also bigger. It is also proved that the multistage hydraulic cylinder designed with CAD/CAE technology can satisfy the requirements of intensity, rigidity and supporting stability.
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