Fundamental Study On The Technology Of Barycenter Measurement For The Large Workpiece With Complex Surface

Experimental investigation indicates that, for the large workpiece with complex surface, there exists deviations between the actual gravity center and theoretical gravity center, which are caused by off-design factors such as poor fabrication precision, material defect and assemblage error. And the deviation significantly influences the performance of the workpiece, especially in dynamic balance. In this case, the problem is engendered in processing and manufacturing, the deviation cannot be determined and eliminated by theoretical design. Therefore, accurate measuring determination of the workpiece’s barycenter position has pretty important practical significance for engineering application, which can evaluate the processing quality of the workpiece and deal with the error compensation.At first, this paper studies the existing barycenter measurement methods. And then it presents a technique for gravity center measuring for a large marine propeller blade in light of the three-dimensional measuring principle for the gravity center. This can be called Barycenter Tilt Measurement(BTM) technology. Combining with the torque balance principle and coordinate conversion, the gravity center can be obtained accurately. Meanwhile, this paper introduced the principle of tilt measuring and theoretical calculation formula in detail.In accordance with the characteristics of the BTM techniques, each function of the program is designed and selected. On this basis, from the two aspects of mechanical structure and measurement software, the system of BTM was projected particularly. So as to set up an experimental platform, the BTM system is applied on a measuring equipment.In view of the characteristics of the system structure and the measuring principle, this paper designs the measuring method of the system errors, and calibrates the errors of the barycenter tilt measurement machine meticulously. According to the error processing criterion and weighted average algorithm, we obtained accurate measurement data and their average value with all system errors corrected in the calculation procedure. The experimental results demonstrates that the BTM system owes high precision and reliability.With multiple barycenter values of propeller blades as study objects, this paper has further research on the Minimum Enclosing Ball of barycenter and the Processing Ball of the blades. And it uses MATLAB for the approximate calculation procedure. Meanwhile, this paper proposes a method of manual removal of weight, which is based on the minimum barycenter moment principle, and provides the specific procedures. The method guides significance for the correction of barycenter the position.