Failure analysis and reconstruction design of the slewing platform mantle of the bucket wheel excavator O&K SchRs 630

Abstract

The slewing platform is the fundamental part of the bucket wheel excavator (BWE) structure. The occurrence and propagation of cracks in the zones of the slewing platform mantle holes, may probably lead to BWE collapse. The goals of the study presented in the paper were to: (1) Diagnose the cause of cracks occurrence; (2) Define the reconstruction design of the mantle; (3) Verify the reconstructed structure by numerical-experimental analysis. The identification of the stress-strain state of the mantle is done by applying the finite element method. Experimental stress analysis of the reconstructed mantle's structure is executed two times in the BWE real working conditions, using methods of strain gauges. The maximum measured value of stress is about 10% lower in relation to the calculated value of stress for the studied load case. Speaking from the engineering standpoint, the mentioned deviation is quite acceptable, particularly having in mind the stochastic character of the excavation process. Besides experimental investigations, the validity of the presented reconstruction also unquestionably confirms the mentioned failure-free exploitation, while the BWE excavated more than 2.6 x 10(6) t of coal after the reconstruction.