Research On Methods For Automatically And Dynamically Measuring Parameters Of Train Wheels

The wheel is a key component of railway vehicles and belongs to consumables. The quality of train wheels have an important effect on the safety of rail transportation. With the continuous increase of the rail vehicle's speed, the wear of wheel is becoming more and more serious, which will certainly bring potential safety hazard to the operation of railway. The wheel geometric parameters automatic measuring technique and dynamically measuring technique can test the wheel quality during the stages of wheel production, regular inspection, and operation. Thus the study on this topic can ensure the safety of railway operation. The main innovative achievements of this dissertation are as follows:1. A method for automatically measuring wheel geometric parameters by laser scanning is presented in this dissertation. The wheel tread can be scanned by the line structured light vision sensors, and the geometric parameters including wheel diameter, flange thickness, tread wear and rim width can be calculated after processing the point cloud data. This is different from the traditional methods which measure the geometric parameters by comparing a measured profile to the standard profile of wheel tread. This method doesn't require keeping strick relative positon between the line structured light and the wheel. The feasibility of this method is demonstrated by experimental results.2. A simple method for dynamically measuring the diameters of train wheels that uses a relative measurement system is proposed. Only a laser displacement transducer and eddy current sensors are used to dynamically measure the wheel diameter when a train passes through the measurement device, and a simple equation for computing the diameter is given. The main factors influencing the measurement uncertainty were analyzed and simulated, The theoretical analysis indicated that the measurement device has a measurement uncertainty of±0.37mm, which agrees with the site experimental results, and the measurement system can satisfy the requirements of dynamically measuring the train diameters in situ.3. The finite element method is used to analyze the influence of vibrations on the dynamical measurement results of train wheel diameter. Meanwhile, the influences of the installation method of laser displacement transducer and the train running speed on the dynamical measurment results are simulated and discussed.