Fatigue Life Analysis And Optimization Design Of Roadheader Turret Based On Whole Machine Vibration

In recent years,china's coal industry has been developing rapidly.The safety and reliability of underground mining equipment in the pit has been increasing.The roadheader,as an important underground mining equipment,works in a harsh working environment.Especially when cutting the rock wall,the roadheader will vibrate violently due to the strong shock load.The severe vibrations can cause damage to key components of the roadheader,breakage of connections and damage to electrical and hydraulic components,which in turn leads to a decrease in the reliability and stability of the roadheader,and also has a huge impact on productivity.Hence,the vibration characteristics and stress characteristic of the key components of the roadheader were studied in this paper.And on this basis,the failure-prone areas of the roadheader are identified and optimized.First,the whole machine model of the roadheader was established according to the drawings of the roadheader using the 3D drawing software UG,and was reasonably simplified according to the requirements of the simulation experiment.According to the modal analysis theory,the x?t file of the machine model was imported into the modal module of ANSYS/Workbench,and the whole machine was subjected to constrained model analysis.The 50 th order vibration pattern of the roadheader in the range of 0-200 Hz for low frequency vibration was obtained,so that the inherent frequencies and modal characteristics of each key component of the roadheader could be obtained.Then,coal and rock cutting simulations were performed in ANSYS/LS-DYNA software.The three-dimensional load spectrum and the torque of the roadheader under the working conditions of cross cutting and drilling were obtained.And,the rigid-flexible coupling model of the roadheader was established in ANSYS/Workbench.Among them,the cutter arm,rotary table,frame and rear support were set as flexible bodies,and the rest of the components were set as rigid bodies.After the cutting load is applied on the cutting head,the transient dynamic analysis of the whole machine is carried out,the vibration characteristics and force characteristics of each key component of road header under cross-cutting conditions were obtained separately.Under the cross-cutting condition,the cutting head vibrated strongly at 15 Hz,28 Hz and 70 Hz.The cutting arm vibrated strongly at 28 Hz,38Hz and 138 Hz.The rotary table vibrated strongly at 25 Hz,51Hz,125 Hz and 138 Hz.The frame vibrated below 20 Hz,but the vibration was not strong.The rear support vibrated obviously but not strongly at 63 Hz,90Hz and 140 Hz.Through the force characteristics analysis,the maximum stress on the roadheader was concentrated at the pin connection between the rotary table and the cutting motor,and between the rotary table and the cutting arm.The maximum stress was 69.73 Mpa.Finally,the fatigue life analysis of the rotary table of the roadheader was carried out,and the dimensions of the rotary table were optimized.The results showed that the maximum deformation of the rotary table pin model was reduced by 13.96% and the maximum stress on the model was reduced by 10.91%.This not only provided a direction for the design and optimization of the rotary table structure,but also reduced the potential failure of the rotary table at the connection with the cutter section.