The subject matter of the article is the processes of virtual localization of near shape parts during adaptive machining. The aim is to develop an effective method for finding the starting location of a CAD model of a part with virtual localization inside a point cloud obtained by laser scanning of a workpiece. The task is to formalize the procedure for starting positioning of the part model as the first stage of the virtual localization process. The second stage for final localization proposed to use iterative algorithms with the objective function which is sensitive to the intersection of the surface parts and the workpiece. In solving the problem the starting position used tools available in today's CAD packages and 3D scanning tools. The methods used are the methods of matrix algebra, in particular, the methods for finding the main central moments of inertia of three-dimensional objects based on the tensor of inertia. The following results were obtained. When calculating the inertia tensor components is proposed to use three-dimensional scanning data of workpiece and geometrical data of part obtained from the CAD system. The result is an algorithm starting location of CAD model in the virtual localization, which in the case of blanks with oversize close to uniform can provide enough current location parts for adaptive machining tasks. It is shown that to minimize computational errors and to ensure satisfactory accuracy of localization proposed algorithm can require several iterations of the shift vector search model. Conclusions. The scientific novelty of the results obtained is as follows: in contrast to the previously used approaches, when solving the problem of virtual localization for the starting position, using the condition of coincidence of the centers of the weight of thin shells coinciding with the surfaces of the workpiece and the part, it was proposed to additionally ensure the alignment of the main central axes of inertia of these shells, which, in the case of near shape blanks, provides a positioning accuracy that may not require additional iterative procedures.
The production of complicated profile parts for aerospace technology is carried out by processing along spatial paths. The nature of the movement of each axis of the equipment is dynamic and unsteady-state. Accuracy must be ensured not only in a steady-state but also in dynamic mode. The determination of dynamic characteristics of the executive bodies is an important and urgent task to optimize the control process. An experimental research method using capabilities of the CNC system, which was equipped with additional hardware and software, is proposed. This allows to register a large number of parameters that describe the state of the equipment, the solving of the task of trajectory interpolating, the formation of control actions, the actual movement of the executive bodies. The methods of conducting experimental studies with the setting of a stepwise change in speed and with a change in speed according to the harmonic law for an open-loop and closed-loop system using various components of the feedforward in the regulator are considered. The use of circular interpolation for the formation of a harmonic law of speed change is proposed. The results of the study of the dynamic of the transition process of an open system are shown. The frequency characteristics of the drive under study are obtained. Its bandwidth is determined. The study of the moving process when the axis velocity changes in harmonic law was performed within the passband. The possibility of determining the maximum permissible values of inertial loads by the nature of the change in actual acceleration is shown. The influence of the regulator feedforward composition on the accuracy of positioning of the servo drive and the accuracy of the contour processing at various frequencies of the control action is studied. For each feedforward method, the frequency ranges of the control action are determined, on which the specified processing accuracy is ensured. It was found that the technological frequency limitation by the accuracy of the reproduction of the path turned out to be significantly more stringent compared to the classical approach for determining the bandwidth.
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