Research On The Online Measuring And Quality Evaluating System For Large Complex Surface

The online measuring and quality evaluating system for the large complex surface,which integrates the NC machine, probe and software together, is to perform measuring work-pieces automatically. Measuring is to match the rough work-piece with its CAD model well (Location) before machining, and to evaluate the quality of the product after machining. This subject is based on the"863"project"Seven Axis and Five-linked Turning and Milling Numerical Control Machine Tool for Manufacturing Large Marine Propeller", researched the principle and technology of online measurement and quality evaluation for large marine propeller, and developed an online measuring and quality evaluating system. In this paper, the following researches have been done.First, it has been studied the principle of online measurement and quality evaluation for large complex surface thoroughly, and given out the demand analysis and overall design of the system.Secondly, key technologies of online measuring and quality evaluating for the large complex surface have been studied as following.The measure-trajectory was planned. The propeller blade surface was modeled with double thrice B-spline method. Measure-points distribution was planned by two ways. They were adaptive distribution according to the curvature of its surface for the rough work-piece, and determination position distribution for the product work-piece. The interference measure-points were taken out and measure-path was planned.The complex surface matching and machining allowance solving have been done. The matching function was built by the Least Squares method, and it was solved by the genetic algorithms. The function was also solved with a simplified method through the fixing craftwork of the propeller.The quality of the propeller blades was evaluated. The blade surface geometric parameter formulas were deduced. When the machining of the propeller blade was finished, the machining surface was measured and the measure-data was gathered automatically. The machining surface geometric shape was evaluated by the data.Thirdly, the software was developed with the development platform of OpenGL-embedded Visual C++ tool, and the system integration has been done.Finally, the tests on the Seven Axis and Five-linked Turning and Milling Numerical Control Machine Tool have been done with the system developed. The results show that the system is very practical, and it also improves the efficiency and accuracy of measuring and quality evaluating for large blade parts.