Research On On-machine Measurement Of Complex Surface Using A Laser Sensor

Complex surfaces are widely used in gear surfaces, blades of aviation engine, aircraft fuselage, automobile body, mold and so on. The quality of complex surface is an important factor affecting the working life, performance and safety of the parts. These free-surface parts are typically manufactured in multiple steps. In order to carry out adaptive process in the succeeding step, the real shape of the part after the preceding step usually needs to be measured. However, the traditional CMM is not only inefficient, but also difficult to conduct field measurements. In response to this issue, an on-machine laser scanning measuring system(OMSM) is designed and implemented, which meets the requirements of the rapidity and the accuracy of the measurement between the multi procedures. The major contents of the thesis include: 1. The general design of the OMSM system is studied, which combines the distance measuring laser senor with five-axis machine tool. Through the machine tool numerical control system, the laser probe can be precisely controlled. What's more, the laser probe can collect 3D points by scanning the contour of the workpiece. 2. The synchronous method between the NC machine tool(motion execution unit), the laser senor(data acquisition unit) and the measurement software(PC) is studied. And the whole system runs correctly with high measuring frequency of the laser senor and high speed motion of the machine tool. 3. A linear calibration method of laser probe installation position and pose is proposed for the OMSM system. This method use a standard ball as the calibration target, through measuring the ball from different pendulum angles and fitting ball center, the optimal solution of laser probe eccentricity and deflection can be obtained. This calibration method is suitable for practical engineering application with simple process and reliable accuracy. 4. According to the structural characteristics of the machine tool, the automatic programming method is studied. The post processing method for OMSM system is given, and finally the automatic programming is realized.Based on the research of related technology, the prototype system of the OMSM system is constructed, and the software is developed with VS2008/MFC. Finally, the OMSM system is verified by measuring an aeronautical blade.