Research On Bolt Connection Characteristics And Strength Of Crawler Frame Of Electric Shovel

Electric shovel are widely used in open-pit mining operations, also the major diggingand loading equipment. With the rapid development of socioeconomic, the number andscale of mines, the market demand of electric shovel in our country are more and more,and also the machine’s performance requirements are increasing. In order to enhance thecompetitiveness and develop products with higher performance, but traditional design me-thods can’t meet the needs of modern design, so how to apply modern design methods todesign better products is the focus of present study.The crawler frame and chassis are connected by bolts, to transfer loads and ensure thestability of the machine; the crawler frames are the main support part of electric shovel,they bear the force transferred from chassis, and then transfer the force to the ground bylower rollers and crawler shoes, so the bolt connection and crawler frame performance re-liability are directly related to the performance of the machine.Finite element analysis(FEA), one of the modern design methods, is applied in thispaper, to do research on bolt connection characteristics and strength of crawler frame of12m3electric shovel. The propel machinery was analyzed based on crawler frame, the as-sembly model which was used for finite element analysis was established, and then theloads of the crawler frame were calculated combined with a variety of unfavorable work-ing conditions. By static analysis, the changes of contact status between the crawler frameand chassis with preload, strength, stiffness and vibration characteristics of crawler framewere analyzed.(1) The analysis of propel machinery structure and the model creation of crawlerframeBy analyzing the whole propel machinery as well as parts structure in this paper，theforce characteristics of crawler frame was known; three-dimensional model of the crawlerframe was created as well as the assembly model with crawler frames, chassis and bolts,the loads was analyzed, and then the model was simplified; after the contacts and parame-ters were set as well as the mesh was completed, the finite element model was attained.(2) The determination of external load of the crawler frameBased on three most unfavorable conditions using for the force analysis of crawler frame: one side brake and one side turn condition, angular mining condition, horizontalmining (heavy side bore by two rollers or single roller) condition, the force characteristicsof the crawler frame were analyzed, and external loads of both side crawler frames werecalculated, in which horizontal mining condition was separated into two conditions, heavyside bore by two rollers and single roller, both conditions were all calculated.(3) The determination of bolt preloadAccord to the methods of load tranferred between the crawler frame and chassis, theprinciples of determining the preload value was proposed. The way to achieve constraintsand loads in ANSYS Workbench were described, did static analysis to crawler frame andchassis in every condition respectively. Through the analysis and comparison of contactstatues, contact pressure and bolt stress in the simulation results, the range of preload valueto meet the connection requirement of a variety of situations was determined.(4) The analysis of the strength and stiffness of the crawler frameCombined with the range of bolt preload, strength and stiffness of the assembly modelwere analyzed in the condition of one side brake and one side turn, angular mining, hori-zontal mining with heavy side bore by two rollers and single roller, detailed stress distribu-tion and deformation of crawler frame were got, and through the analysis and comparisonof local stress and deformation of crawler frame under different preload, the influence tostrength and stiffness by preload was got.(5) The study of vibration characteristics of crawler frameBased on equivalent contact area method, modal analysis of assembly model was did,the natural frequencies and mode shapes of the assembly model were got. The frequency ofexcitation sources during mining operations as well as the process of walking were ana-lyzed, excitation frequency can’t cause resonance by calculating. Through the analysis ofthe mode shapes, the anti-vibration performance of every position of the crawler frame wasgot.