Three Gorges Hydroelectric Generator Mirror Plate Flatness Measurement Method

For manufacturing the important equipment for Sanxia project,measurement instrument was urgently needed to measure the planeness error of the Big Mirror(a part of thrust bearing). But now,there is no good method for the measuring of planeness of high precision large plane. A research for one good method for Sanxia Big Thrust Bearing Plate planeness error measurement was done and described in this dissertation.According to the requirement of Sanxia Big Thrust Bearing Plate planeness measurement,based on overall analyzing and studying of the previous researches,a new method was proposed. It was named as Gradienter random automatic moving planeness error measurement method for Big Thrust Bearing Plate.The following research work has been done:Position kinematics analysis was done. Using a mathematics tool:Homogeneous Matrix,the transformation of measurement coordinate was built. Through it all measurement positions are described in one coordinate. This is needed for planeness error calculation.Motion control was studied. By mechanical and control system design a combined motion control mode was mad. It includes both position control and force control. This made sure an automatic movement and measurement system was designed.Using the advantages of both the single-piece computer and desk computer,divided control system and data process system was made. Single-piece computer is for fieldwork and desk computer for complex calculation work.Based on studying of the methods for planeness error calculation,one suitable method was selected. It is the Least Square method.A real measurement system was designed and manufactured. It includes five main parts:mechanical structure,high precision Gradienter,measurement control system,data recording and processing system and soft ware for coordinate transformation and planeness error calculation.The accuracy of the measurement system is 2.4um,the repeatability is 0.8 um. It is suitable for measuring Sanxia Big Thrust Bearing Plate. The project has passed the acceptance of Sanxia project office and the instrument has ordered by the company that will manufacture Sanxia Big Thrust Bearing Plate.Zhang Jingcai (Mechanical Design and theory) Directed by:Academician Lei Tianjue Professor Cheng Yuexiang...