Study On Non-contact Measuring Precision Of Wheelset Geometric Parameters

The non-contact and automatical measurement of wheelset geometric parameters not only can help to improve the quality of wheelset test, to realize the goal of railway' s information management, but also can give much information on the studying wheel-rail geometric contract. Therefore, the study on technology of automatical measurement of wheelset is of much importance.The precision of a new project for measuring the wheelset geometric parameters is studied once again in this paper. First, the wheelset is fixed and rotated by the device used in vehicle depot as usual. Second, the center line of wheelset axis is determined by a device called axis-center probe. Last, the acting device for sensor can draw a whole felloe profile, which is made up of parallel-pole device and rotating-probe. The wheelset profile is scanned by the eddy current sensor, thus, the geometric parameters of wheelset will be get.The theory of the measuring system and the kinematics of parallel-pole are analyzed. The whole electric components are implemented in the measuring system by employing grating sensors and optical encoder with resolution and low error. The measuring system also has a position and control precision with stepping motor.The influence which the single error has on the measuring result of measurement system is studied. The source of error that has great influence on measuring result is found, and this offer evidence to precision design for improving the measurement precision of measuring machine.The uncertainty of measurement machine at assured point are analyzed. It can be known that the encoder' s zero angle has great influence on measuring precision, and it must be calibrated. The machining precision of IT7 can satisfy requirement of measuringmachine.A self-calibration mathematics model for contact measurement machine is set up in this paper, and it is proved by emulational method for single error. A calibrating scheme that calibrating module are scanned and measured with the eddy current sensor is designed. The result of experiment about the wheel profile show that the feasibility of non-contact measurement using eddy current sensor is turned out.