Crack Analysis And Structural Improvement Of Axle Seat Of Locomotive

Aiming at the problem of cracks in a certain proportion of axle seat exposed during the implementation of the relevant locomotive after a certain mileage,the analysis of crack characteristics at the axle seat,the mechanism of crack generation and the appearance of cracks as well as the previous analysis data on the microcracks at the axle seat,it can be seen that the characteristics of the axle magnetic trace display are consistent with the fretting wear fatigue crack characteristics.The wheel press-fit parts of the railway machine are connected by interference fit.When subjected to the rotating bending load,a slight cyclic reciprocating relative slip occurs between the mating surfaces at the edge of the axle press-fit part,resulting in micro-motion.The production of damage.The fretting fatigue of this part is one of the main forms of railway axle failure.The unloading groove near the wheel seat can greatly alleviate the stress concentration of the mating edge of the axle,thereby affecting the fretting fatigue performance of the axle press-fit part.At the same time,the amount of interference is also an important factor affecting the fretting fatigue of the wheel press.The TB/T1463-2015 standard only specifies the range of interference(0.9‰~1.5‰ of the diameter of the wheel seat),but does not give the relationship between the fretting fatigue performance of the wheel press part and the amount of interference.Therefore,it is very necessary to study the influence of the unloading groove depth and the interference amount on the fretting fatigue resistance of the axle press-fit part,so as to optimize and improve the structure of the part.(1)Study the influence of the interference between the axles on the fretting fatigue,and select the upper limit of the interference standard,the median value of the standard,and the lower limit of the standard,respectively,to compare the effects of fatigue performance.(2)Calculate the fatigue strength of the original axle at the wheel seat(unloading depth 1mm,inter-axle interference between 0.26-0.33),confirm whether the initial design meets the maximum fatigue strength of the material.(3)The depth of unloading groove at the original axle wheel seat was studied.The depth of unloading groove at the wheel seat was deepened from 1mm to 2mm and 4mm.The influence of the depth of unloading groove at the wheel seat on the fretting fatigue performance was studied.Considering comprehensively the influence of deepening the depth of the unloading groove on the stress level of the unloading groove itself,the too deep unloading groove will cause the crack of the unloading groove itself.Finally,the 2mm unloading groove depth optimization scheme is selected.(4)Continue to deepen the depth of the unloading groove and deepen the depth of the unloading groove to 4mm.If the depth of the unloading groove at the wheel seat can improve the fatigue performance,it is studied whether the fatigue performance can be further improved by further deepening the unloading groove,and the stress level is also evaluated.(5)Adjustment scheme of final confirmation for the quality of process card control(excluding schemes perform adverse effects),and to adjust the axle after tracking verification,confirm the improvement effect is good,can reduce or avoid the locomotive axle crack problem,also can through the scheme will axle existing shallow crack depth(less than 2 mm)to eliminate,reduce the cost of replacing new axle.(6)At present,it has been implemented successively in locomotive C5\C6 repair program(railway locomotive overhaul program),1345 pieces have been completed,8070 axle optimization programs have been implemented,and no axle cracks have appeared.