Research On The Anti-impact Characteristic Of Hydraulic Luffing System On Mobile Crane

Mobile crane is one kind of engineering mobiles widely used in architectural industry,railway construction and mining industry, mobile crane is also the uppermost sort of engineering cranes.The hydraulic system of mobile crane includes up-part system and under-part system, the up-part system constitutes of rotating system,hoisting system,luffing system and extending system. Currently almost all the mobile cranes made in China exit hydraulic impact and unstable boom swing during the valve has a little opening. Increasing the boom's rigidity can reduces but can't thoroughly eliminate the boom swing.Taking the hydraulic system of Zoomlion's QY25 mobile crane as the object, using the method of theoretical analysis, computer simulation and experimental analysis, this thesis researches the hydraulic impact and boom swing that exit in luffing system. This paper established Amesim model of the up-part hydraulic system and analyzed it with the dynamic analysis software. Based on the simulation model of the boom and key components of the luffing system, the parameters of the luffing system were modified and tested to recur the abnormal working conditions of the mobile crane. Several modifications were carried out to the multi-way valve of the luffing and the counterbalance valve. After modified, the luffing system was experimented on a real crane truck and the testing data was collected on site. The experimental results showed that the above-mentioned problems could be reduced efficiently after modification. The main content of this thesis could fall into six chapters as the followings:In chapter 1, the history and current research status of mobile crane are introduced based on a lot of the publications and conference papers. Consequently, the goal of research and project are brought forward.In chapter 2, in-depth analysis of the multi-way hydraulic system and abnormal working problems, and established Amesim model of luffing system that can recur the actual hydraulic impact and boom swing.In chapter 3, modifications were carried on multi-way valve and counterbalance valve through theoretical analysis and hydraulic simulation to eliminate impact and boom swing. Experimented on a real crane truck and the collected testing data to provide theoretical basis for further optimization.In chapter 4, aimed at that the luffing system pressure and back pressure were too high and effective hydraulic power was low after modification, optimizations were carried on multi-way valve and counterbalance valve. Experimental results showed that system pressure and back pressure were effectively reduced, performance of hydraulic system was increased.In chapter 5, hydraulic test base was built up to contrast the performance of two counterbalance valves before and after optimization.In chapter 6, some conclusions in this thesis were summarized and the future research proposals were suggested.