Research On Principle And Key Technologies Of Geometric Parameter Measuring For Radome

In the aeronautic and astronautic industry, the radome of missile is large complicated and thin-wall rotary object, the shape of which is parabolic nose-like cone, with its length being about one meter and the diameter in the cone bottom a third of its length. At present, there is no available measuring instrument for accurately and quickly measuring the geometric parameters of the radome, which hinders raising of the manufacturing precision of the radome, affecting the development of the missile.Based on the theory and technologies of measurement, instrumentation and radome design, and the analysis of the measuring requirement, a novel measuring principle is proposed and a special measuring system & instrument has been developed to provide an innovative, precise and quick-process solution for measuring the geometric parameters of missile radome, especially for directly measuring the normal wall thickness, by means of integration of new measurement principles, information transmitting & processing, CNC control, transducers, and microelectronics. The research mainly contains the measuring principles and the general scheme, the models and algorithms for profile error evaluation, the implementing of the control system and the software solutions, the graphical presentation methods for measurement results, and the evaluation method for measuring precision.The principle and the general scheme of the geometric parameter measuring are firstly studied. Based on the measuring principle, the measuring system is designed with two work stations for measuring of the wall thickness, the outer contour and the radial run-out respectively. Both the wall thickness and the outer contour are measured in one instrument. The workpiece is clamped slantways in the instrument during the wall thickness measurement in order that the measurement results from two work stations can be matched each other.In the wall thickness measurement, an innovative measurement principle is proposed. The hinged point of the jaw-like measuring arm moves along a locus formed by a series of points that are on a series of lines tangent to the outer contour with identical distance from the tangent points.In order to eliminate the systematic errors in the measurement, the profile error evaluation method is studied. The original deviation of the workpiece contour is analyzed by the evaluation methods integrated with the least-squares and the minimum zone evaluation models, based on the saddle-point programming principles, the Frenet moving frames and the Cecaro methods. The linear geometric model, the original normal error algorithms, the programming models and algorithms, the minimal condition, and the practical processing method for the profile error evaluation are presented.The measurement and CNC control system is researched and constructed with open architecture based on the integration of the IPC, the numerical controller, the servo mechanism and the measuring devices. The scheme, the description, and the key technologies for the measurement & control system are presented. The software system is developed using the object-oriented programming and the concurrent development method. The feasibility analysis of the real-time control under Microsoft Windows is conducted and the technical solutions are given. Moreover, the technologies for moving locus generation, data acquisition, running process control and software PLC implementing are introduced.For viewing the deviation of the outer contour and the wall thickness directly, the measurement results are graphically presented by means of the 3-D error effect graph, the equal-deviation chart and the section graph. The Valid Area Method for 3-D error effect graph and the Mesh Element Information Discriminating Method for equal-deviation chart algorithm are put forward.Practical measurements have been carried out to test the functional performance, measuring precision and the measuring repeatability of the measuring system. The evaluation methods for the measuring precision, together with the evaluation...