Fatigue Simulation Test Research On Raceway And Inner Gear Ring Of Main Bearing Of Shield Machine

The main bearing of the shield machine is a key component of the large roadheader.Once it fails,the roadheader will be shut down for a long time or even scrapped.Therefore,the main bearing of the shield machine needs to meet the high reliability under complex working conditions,and its service conditions are complex.In the process of service,it needs to withstand large overturning moment,large torque and impact load,and its ferrule has large diameter,thin wall thickness,wide end face,poor structural rigidity,and is prone to large deformation,abnormal vibration and premature fatigue failure.Based on this,in order to improve the reliability of the main bearing of the shield machine,an accurate fault tree model of the main bearing of the shield machine is established in this paper,and the fatigue simulation test research is carried out on raceway and inner gear ring of main bearing of shield machine.The main contents of this paper are as follows:(1)Referring to the disassembly and inspection reports of several main bearings of shield machine,through the statistics of their failure forms,the failure fault tree of main bearings of shield machine in service is constructed,and the fault tree is analyzed qualitatively and quantitatively.By investigating all the failure data of 60 sets of main bearings of shield machine,it shows that the quantitative analysis results are consistent with the actual situation.It is concluded that raceway fatigue,inner gear ring fatigue and corrosion are the main failure forms of main bearings of shield machine.(2)Based on the finite element simulation,the fatigue of raceway of main bearing of shield machine is numerically simulated.The rolling contact behavior with surface defects is studied by inserting a semi elliptical crack on the surface of raceway of main bearing of shield machine.The results show that the fatigue failure of raceway surface crack is mainly caused by mode(40)and mode(40)(40)crack,the influence of mode(40)(40)(40)crack is small,and the fatigue growth at the crack tip is caused by the combined action of surface traction and normal load.By changing the load,surface friction coefficient and rotating speed,it is found that these parameters have a positive correlation with the effects of mode(40),mode(40)(40)and mode(40)(40)(40)stress intensity factors,and have a great influence on mode(40)and mode(40)(40)cracks,but have a very small effect on mode(40)(40)(40)cracks.(3)Based on the finite element simulation,the crack propagation on the surface of raceway of main bearing of shield machine is simulated,and the variation law of the stress intensity factor at the crack tip with the crack propagation is obtained.At the same time,the crack propagation trajectory on the surface and inside of the raceway is obtained by calculating the crack propagation rate and crack propagation angle.Finally,the crack propagation life is predicted based on the Paris formula.(4)Based on various experimental instruments,the fatigue of inner gear ring of main bearing of shield machine is analyzed.By analyzing the test data,it is found that the original crack source of inner gear ring of main bearing of shield machine is produced in the process of quenching and cooling.