A Study Of Winch System For Wheel Crane In The Over-running Load Condition

Liftting machinery is one of the indispensable engineering machinery in engineering construction and plays a pivotal role in economic construction of China. Especially,along with the rapid development of our country's economic and social, for example, high speed-rail, petroleum and chemical industry, construction and other industries, the required amount of lifting machinery in market is more and more, the role of liftting machinery are becoming ever more important. Wheel crane has a particularly prominent position in liftting machinery which has many kinds, and been used widely with the advantages of free wheel crane portable chassis, and Multi-work Condition etc. The application of wheel crane greatly improves the human labor productivity, reduces labor intensity and accelerates the economic construction.Since launching in markets ,the wheel crane has been experienced a rapid and healthy development period, but with the rapid development of science and technology, users's requirements for the wheel crane operating performance are increasingly high. The hoisting system is one of the most key subsystems of wheel crane, the performance of hoisting system will have a direct impact on the whole operating performance of wheel crane. Therefore improving the performance of hoisting system has a very important significance for ascending crane reliability. At present, the flaws: down dithering and second hoisting slumping in hoisting system of Wheel crane, make that the crane can't play normal hoisting performance, extremely, and may cause serious safety accidents, so the study of Winch Lower Performance for wheel crane has very an important properties and technical status.This paper will take wheel crane which is used widely as a prototype of the car, test and analyse the hoisting hydraulic system performance of wheel crane. According to the problems existing in the hoisting system, the down dithering is mainly researched on. The paper designs a new balance valve cover with damping network by the testing and analyzing of hoisting system performance. New balance valve cover with damping network has an important affection on pressure filtering which makes the pressure into balancce valve pilot control oil chamber more steady and will make balance valve and brake get a good matching for the time of opening and closing mainly through the application of damping network. Therefor the down dithering of hoisting system is eliminated , and the hoisting system performance is promoted to the full extent. This paper mainly do the following:(1)Several current domestic and international hydraulic controling system of hoisting mechanism of wheel crane have been introuduced. Also, the paper mainly analyzes the advantages ,disadvantages and the control principles of open-type hydraulic system with valve-controlling,open-type hydraulic system with pump-controlling and closed hydraulic system with pump-controlling, and provides a theoretical reference for the optimization design of hoisting system of wheel crane.(2)Testing the performance of the hoisting system for the wheel crane on each condition, and excavating the related factors which mainly influence the performance of hoisting system by analyzing the test data. Test results show that the wheel crane which is learned exists the flaws: down dithering when operating. We know that the pressure of balance valve pilot control oil chamber is fluctuant by the analysis for the tested curves, and the opening and closing time get a wrong matching between balance valve and brake ,this will cause the pressure oscillation of hydraulic system, and then will appear down dithering.(3)Using damping network matching technology and optimizing the balance valve pilot oil channel through the analysis of the mechanisms of down dithering of wheel crane.Also,this paper designs the new balance valve damping network cover. When matching the parameters of new balance valve damping network, not only considers the good filtering performance, but also for on-off time matching of balance valve and brake. Deriveding the calculation formula of damping network parameters for matching, and provides a computation basis for the reasonable selection of cover parameters.(4)Modeling the typical crane hoisting system by the AMESim software, and simulating according to actual working condition, mainly analyses the lower performance of the hoisting system of the wheel crane. The results of simulation show that the closing time between balance valve and brake of the learned crane is unreasonable, in some conditions, this will cause down dithering phenomenon. To enhance the reliability of hoisting system, some reasonable measures will be taken to eliminate the defects.(5)Modeling and simulating the new hoisting system by using the AMESim software, and analysing the performance of the new lifting system of wheel crane. Simulating by using different damping network parameters, and the results show that the new damping network cover make the balancce valve and brake get a right matching on-off time.Also,the new cover make the pressure of the balance pilot chanmber more steady, to the full extent, the lower performance of the hoisting system has been improved. (6)According to the results of the theoretical calculation and simulation analysis, the new damping network had been tested, the results showed that the new damping network cover has a good influence on the stabiliy of balance valve pilot control pressure for and can make the balance valve and brake get a more reasonable on-off time matching.As long as the selected parameters is appropriate, the new damping network can effectively solve down dithering of hositing system of wheel crane.In this paper, the using of damping network technology optimized matching parameters and the parameter relation of key control components of hoisting system, theoretically, provides scientific basis for the promotion of lower performance. And modeling and simulating the hositing system by the AMESim software, demonstrating the validity of the theoretical analysis from the angle of simulation, and also the result of the real car testing validate the effectiveness of simulation. The data of simulation and the real car test show that the new design balance valve cover in the paper has a good damping effect, can effectively solve the down dithering of hoisting system, greatly promoted the reliability of hoisting system of wheel crane.