Research On The Detection Technology Of Train Wheel Tread Wear And Instrument Developing

With the rapid development of high-speed railway,the speed and traffic density of trains have risen steadily,the start-stop and the accelerating or decelerating frequency of trains have increased obviously,which results in the aggravation of wheel tread wear.Tread wear will result in the decrease of adhesive force between wheel and rail,affect brake performance of trains,generate impact force on the rail,and bring seriously influence on train operation stationarity and safety.Therefore,they are necessary to inspect wheel tread at regular intervals or mileage,repair or change the problematic wheel in time,and so to guarantee railway traffic safety.The repaid development of high-speed railway and city subway bring up with urgent need for high efficiency,high accuracy,and easy operated instruments to detect wheel tread.Therefore,this thesis conducts research on wheel tread detection technology and portable high-accuracy detecting instruments development by use of laser displacement sensor.Main research contents are as follows:First of all,wheel tread profile characteristics,essential parameter,tread wear and its technique requirements for detecting are analyzed.Being aimed at the characteristics of large wheel tread profile size range(28mm or larger)and large contour curve slope,the direct-type laser displacement sensor has been adopted and a reasonable scanning measurement scheme has been designed by the use of comparing the characteristics,advantage and disadvantage between direct-type and oblique-type triangulation method.Secondly,the measurement accuracy of laser displacement sensor is related with the beam incident angle.The wide change range of wheel tread contour slope results in a large change in beam incident angle,which affects measurement accuracy and even occurs distortion.To solve this problem,the thesis has carried on the experimental research on the relationship between incident angle ? and measuring error(35)L,and presented a simple experiment method.The conclusions are as follows:(1)(35)L increases with the increase of?.Also,when ? is smaller,(35)L changes slowly along with?;when ? is larger than certain angle,(35)L increases quickly along with ?.(2)For different material and different surface quality,it is not consistent that(35)L varies with?.At the same ?,the better smoothness is,the smaller(35)L is.Thirdly,the portable wheel tread wear testing device has been designed and manufactured.It has following features: the sensor has been installed at certain oblique angle ? to avoid measurement distortion because of larger ? within whole tread profile.Scanning motion mechanism adopts stepper motor + screw-nut pair transmission,and the scanning motion of the sensor has been achieved by use of adjusting the subdivision times and pulse frequency.Stepper motor and the lead screw are through shaft structures with compact mechanism and small volume.Fourthly,the measurement experiment has been performed on the portable wheel tread wear testing device based on NI ELVIS ?+ & computer and by means of Lab VIEW procedure.An actual wheel tread is measured at different installed oblique angle?.Measuring results are in good agreement with tread's actual contour,which verifies the feasibility and reliability and effectiveness of the device and lays the foundation for the realization of the product.