Abstract:Outofround of wheel profile is an important factor affecting the highspeed running of rail locomotives. Combing with the design of latemodel underfloor wheelset lathe, this study focuses on the online turning and measuring profile of wheel tread. An onmachine measurement and evaluation method for the outofround of the wheel profile is studied, and an embedded onmachine measurement system based on the numerical control system is developed. In this work, the measurement model of the wheel tread, data processing, wheel center positioning, and evaluation methods are discussed. The dynamic extraction and separation method of the wheel profile is also proposed to strengthen the onmachine measuring accuracy of measurement device. In addition, the order refinement analysis method is used to solve the physical resolution and measurement accuracy of the loworder polygon, which can improve the evaluation accuracy of the outofround of the wheel profile. Finally, experiments verify that the repeatability of the onmachine measuring has reached micron level. This work can effectively improve the measurement and evaluation of the locomotive wheel profile, and it can also promote the work performance of the underfloor wheelset lathe.