Rigid-flexible Coupling Dynamics Analysis On The Undercarriage Of Large-scale Mining Excavator

This research is supported by the National High-Tech Research and DevelopmentProgram of China (863Plan)(No.2012AA062001): Design of75m3large-scale open pitmining excavator. The key components of the undercarriage of the WK-75large-scalemining excavator: the slewing bearing and the crawler running device were investigated inthis paper, the rotary time of the slewing bearing and the driving power of the running devicewere calculated, and separately the rigid-flexible coupling dynamics analysis of the two partsof the undercarriage was conducted.Based on the relevant domestic and foreign literatures, the research and applicationstatus of the undercarriage of large-scale mining excavator was summarized. Because thelarge total weight, complex force condition of the undercarriage during operation and thedefect that the traditional finite element and dynamics analysis couldn’t display thestrain-stress status during operation, the rigid-flexible coupling dynamics analysis wasproposed to analyze the excavator’s undercarriage.Relevant parameters of the undercarriage were calculated, as for the slewing bearingdevice: the rotary time under the condition that the bucket rob was fully extended with thebucket filled and the bucket rob at the original position with the bucket empty was calculated.As for the crawler driving device, the driving power under specific conditions, such ashorizontal, climbing and spot turning conditions were calculated.Because the construction features of the thrust roller bearing of the undercarriage, therollers and the central pivot were made flexible and the other parts still kept rigid property inorder to obtain the rollers’ strain-stress state during operation. According to real constraintcondition, a rigid-flexible coupling model about the slewing bearing device was built,dynamics analysis about this coupling model under two different working conditions wereconducted, the force distribution of the rollers and the strain-stress state of the rollers and thecentral pivot was obtained.Crawler frame as the major supporting device of excavator undercarriage, its force stateis complex, so in order to better analyze it, rigid-flexible coupling model about the crawlerframe was constructed with the crawler frame flexible and the other parts rigid. Byrigid-flexible coupling dynamics analysis of the three working conditions, the driving powerof each condition was obtained and the strain-stress status of the crawler frame was analyzed;furthermore as for the force state of the track wheels and the super connecting bolts whichwere difficult to calculate by theoretical analysis were observed after simulation.The simulation result shows that the rigid-flexible dynamics analysis method couldbetter analyze the strain-stress state of the undercarriage of large-scale mining excavator during working conditions, and it offers some certain value for the design of theundercarriage of large-scale mining excavator.