| The crawler crane is a floating crane that the lifting operation is on the trackedchassis and that it’s moving rely on track device. Along with the increasing ofdomestic energy production facility and infrastructure construction for oil andchemical industry in recent years, the demand of the large hoisting equipment isincreasing. The crawler crane has the advantage of moving with load, longer armlength, good lifting performance, higher working height and bigger range. Thesecharacters cater to the demand of the market so that the market of the crawler crane isup rapidly in recent years. At the same time, the manufacturing enterprise of domesticcrawler crane seized the opportunity and got rapid development in past several years.The rotary table and the pedestal are the foundation of the crawler crane and thesystem having largest and the most complex stress. The weight of the slewingplatform and the pedestal take up more than30%of the total weight of the crane.Along with the structure of crawler crane develops gradually toward the big tonnage,not only the weight of the crane increases accordingly, but also the load bearing bythe slewing platform and the pedestal is increasing gradually. The result is that thedemand of structure stress for the slewing platform and the pedestal is higherstandards too. In crawler cranes currently used, some occured the problems, such asbolt looseness and pedestal deformation etc. The more serious accidents happened dueto the insufficient stress strength of the slewing platform and the pedestal. Thisdirectly caused huge economic losses.Another factor is worth noting that the transport cost has certain portion of thewhole cost of big tonnage crawler crane, and the surplus of stiffness and strength canincrease the weight of the crane, accordingly increase the transport cost and influencethe market competitiveness in directly. Under this situation, it is urgent to do structureanalysis in-depth for the rotary table and the pedestal.In the present study, major contents are as follows: 1. Reviewing the source and the background of the crawler crane research topic,the status of development of the crawler crane domestic and overseas in additionsummarize the research status In the domestic about crawler crane. Expounding thetheoretical meaning and realistic significance to numerically analyze the slewingplatform and pedestal for crawler cranes by using finite element method.2. Introducing the function and the main form of crawler crane’s slewingplatform and pedestal in the market, and establishing the finite element simplifiedmodels that generated by using the HyperMesh software according to eachcomponent’s mechanical characteristics.3. One side, numerical calculating and analyzing the strength of stress to thecrawler carne’s slewing platform and pedestal, respectively, by using traditional finiteelement analysis method, the other side, the actal test of the stress is carried out forthe crawler crane’s slewing platform and pedestal in order to verify the numericalsimulation resultes. The analysis of results from the calcultiong and test shows thereare the significant errors between numerical simulated values and test values of thestrength of the stresses, especially near the slewing bearing.4. In order to improve calculation errors, a new finite element analysis methodfor crawler cranes is developed based on a new assembled model through girder androd structure to simulate slewing bearings in the present study. The difference of thenew method with respect to the traditional analysis method is that it can assemble theslewing platform to the chassis of crawler cranes and form an assemble model.5. Comparing the calculation results from the assembled model by using newcalcultaion method and from split models by using traditional calculation method,respectively, with test data, the contrast results show that calculation results fromthe assemble model are more accurate, especially, structure stress near the slewingbearing. This also shows it is necessity using the assembled finite element analysismodel to analyze crawler cranes.6. Finally, using new calculation method combined with ANSYS optimizationmodule improves the slewing bearing of crawler crane and optimizes the thickness toweight loss the slewing bearing, and made a good effect. By using ANSYS and HyperMesh software combination treatment practicalproblems, especially for slewing bearing of the reasonable simplified, and use APDLlanguage to establish the slewing bearing’s simplified model of, the slewing platformand pedestal for crawler cranes computing structure analysis method can also apply toturn back to the structure of the supporting similar engineering equipment such astower cranes, truck cranes, excavators for similar structure analysis. |
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