Study Of Key Technologies In High Speed Interpolation Based On Machine Tool Dynamic Characteristics

During the process of high speed machining, dynamic characteristics of machine tool play a much great impact on machining efficiency, contour accuracy, surface quality of the part machined. Therefore, interpolation algorithm simply based on the geometry shape of the part machined can no longer meet the needs of high speed machining. In this thesis, in allusion to high speed machining, a high speed interpolation algorithm based on the dynamic characteristics of machine tool and the geometry shape of the part machined is established; A multi-object oriented interpolation strategy is proposed; An interpolation algorithm testing platform is built to validate the high speed interpolation algorithm. Major study of this thesis is as follows:Driven characteristics of servo motor are firstly analyzed in this thesis, and then machine tool dynamics constraints are created which is based on the load power and dynamic characteristics of machine tool. Combining with geometric constraints of part machined, compounding constraints of a forecasting control interpolation algorithm based on the dynamic characteristics of machine tool is established. As to compounding constraints conditions, a pre-estimating analysis is carried out upon them, actualizing the forecasting control module and pre-interpolation module of small line blocks and NURBS interpolation algorithms. According to the characteristics of small line blocks and NUBRS interpolation algorithms, analyzing the instruction parameters which impact high speed machining, and minutely analyzing the impact to geometric objects made by instruction parameters (instruction acceleration, interpolation cycle, instruction precision and so on), then setting forth a multi-axis interpolation strategy based on the dynamic characteristics of machine tool.As to small line blocks interpolation algorithm and NUBRS interpolation algorithm, the existing estimating platforms of interpolation algorithm performance are extended in this thesis, offering indexes such as interpolation algorithm contour accuracy, machining efficiency, dynamic characteristics, frequency spectrum of machining process and so on. A variety of object testing can be achieved through this platform. One can test various interpolation algorithms, in order to validate the correctness of the interpolation algorithms designed. At the same time, according to characteristics of the machining curve and machining requirements of the part, different instruction parameters can be inputted into it. So one can compare the machining results and analyze them, sorting out the best solution, reducing the money cost by trial cut, and saving the machining time.In order to validate the interpolation algorithms designed, an algorithm testing platform is established. This platform is constructed on the basis of CAN bus architecture, using Linux real-time kernel. And it can achieve 2ms as the minimum interpolation cycle, so the accuracy of sampling can be guaranteed. The above two interpolation algorithms are embedded into this platform, and they're tested under different machining instruction parameters, validating the feasibility of interpolation strategy. Simultaneity, comparing the testing results with simulation results under the interpolation algorithm performance evaluation platform, the results shows a very high correlation between the two results, accordingly proving the enforceability of testing the interpolation algorithm designed under interpolation algorithm performance evaluation platform.