Structural Modification Of Planetary Differential Mechanism Of Ship Unloader

Phase one ore has been put into operation for more than ten years in Tangshan Caofeidian Industrial Port Company Limited since 2005.The 2500t/h bridge grab ship unloader which belonging to the wharf works continuously for a long time.Fatigue damage has begun to occur in the bearings of the reducer and the replacement cycle has become shorter and shorter.It causes so repeated and long downtime maintenance of equipment that have a tremendous impact on the production efficiency of the company.In order to extend the working life of the reducer,this subject aims at the shortcomings in the design of assembly form between solar wheel and planet carrier,the structure of planetary differential mechanism of ship unloader is reformed and designed.Thus,the safety and reliability of the ship unloader are improved.The main contents include:Firstly,the study drew the motion sketch of transmission system mechanism according to the assembly diagram of planetary differential mechanism,and analyzed the transmission principle of grab hoisting/opening and closing mechanism and trolley running mechanism.The four motion modes of differential mechanism were analyzed respectively and the relationship between the rotational speed of the hoisting/opening spool and the relative motion between the solar wheel and the planetary frame were solved.Then,according to the composition and failure mode of the differential mechanism function package of grab ship unloader the study analyzed the main causes of its failure and gave the sources and properties of the axial loads on deep groove ball bearings;The study completed the improved design of differential mechanism which discarded the deep groove ball bearings between the solar wheel and the planetary frame and adopted the spherical top block structure to improve the bearing capacity of the solar wheel.Based on hydrodynamic lubrication theory,the basic equation of Point Contact Elastohydrodynamic Lubrication for spherical top block was derived and a fluid-solid coupling finite element analysis model was established by ANSYS workbench.The study adopted the one-way fluid-solid coupling analysis method and analyzed the oil film pressure distribution on the coupling surface,discussed the velocity direction and variation law of lubricating oil flow,solved the equivalent stress and strain at spherical surface.Based on the results of finite element analysis,the effects of lube oil viscosity and relative velocity on the oil film pressure and flow field were discussed.Finally,through the tracking observation of the running time of the equipment before and after the modification,it was found that under the same working conditions,no abnormality has been found on the tooth surface of the solar gear of the equipment after the modification.Practice has proved the rationality of structural transformation,which can improve the strength and service life of differential mechanism,reduce the failure rate of ship unloader and improve its working efficiency.