Étude du profilage d'outil de meulage dédié aux procédés robotisés

Abstract

The Research Institute of Hydro-Quebec (IREQ) developed a portable robotic technology (SCOMPI robot) to automate repair and maintenance processes for hydroelectric turbines. During the grinding process, some surfaces with high curvature, such as fillets, are not yet attainable by the robot and must be corrected through manual grinding tasks. The problem with the use of robot in these areas is fast wear of grinding wheel which makes it difficult to control the orientation and position of the robot, considering the changes in shape of the wheel. This thesis presents a method to maintain the profile of the grinding wheel during the grinding process in order to improve material removal control. An analysis of grinding wheel profiling allows identifying the features and limitations of this new process. Several tools have been developed to modify plug wheels, commonly used for this type of operation. Drilling and truing the wheels allow the robotization and the study of the process of profiling. Measuring instruments and experimental methodologies have been developed to measure the grinding parameters. A wheel profile measuring bench and a normal force measuring bench have been developed. Grinding bench characterization made it possible to define the control parameters of the grinder and compensate the compliance of the SCOMPI robot during the process. The objective of this step is to optimize the grinding power control during the process. Several material removal and wheel wear models were developed and validated by experimental tests. These tests have identified the importance of combining the grinding power and the normal force to increase the robustness of material removal and wheel wear models. The results also showed that it is much more difficult to predict the wear of the wheel compared to the material removals. In order to achieve the profiling operation, an oscillation model of the wheel is proposed and tested experimentally. A series of tests has shown that the oscillation of the wheel on the work piece improves the control of the Wheel profile and increases the material removal rates. The modeled oscillation minimized the profile error more than 25% compared to a linear oscillation. Grinding power control and flexibility compensation of the robot are found as the key elements to optimize the grinding wheel profiling process. Overall, this research lays the groundwork for grinding wheel profiling dedicated to robotic grinding process and identifies the factors which are important for developing this new process.

Date	22 Jul 2013
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Zhaoheng Liu (Supervisor)