| Series-parallel NC machine tools breaks up the concept of the traditional structure, and it has the features of the big working space and mature NC system of the traditional C-series machine, at the same time, it also has the features of high accuracy and good rigidity of the parallel machine tool, which greatly increases the stiffness of the machine, and improves processing accuracy and processing quality, so it is suitable for complex surface processing. The servo system is a high-precision complex electromechanical system with stability structural, efficient movement and accurate control.The electromechanical coupling characteristics of the servo system for 3-PTT series-parallel NC machine tools is studied in this paper, and the fundamental purpose is to explore the kinematic constraints on the coupling mechanism, and analysis the coupling parameters of this system and movement-related mechanisms. This study can guidance NC machine tools servo system design and optimization of the parameters match, and solve the problems of low machining accuracy ,efficiency, insufficient reliability, simultaneously, improve the overall performance and production levels of NC machine tools.This study designes a series-parallel NC servo system structure for complex surface machining, and analyzes machine body conformation, kinematic pair types, connected components, spatial degrees of freedom by using the method of decomposition and synthesis. And then, this study analyses the working space using singular constraints and couple factors, after analysing, the simulation is carried out, and the simulation results accurately reflect the actual range of machining. Reference basis for discipline of configuration and analysis of kinematics and dynamic has been provided.The mechanical coupling characteristics for series-parallel NC machine servo system is researched, which involves in the calculation of mechanical coupling parameters, model and simulation of statics coupling, model and simulation of dynamics coupling. The analysing of statics shows: the stiffness of the key componets of the NC machine servo system and the bearing forces and deformations conform to the needs of machine tool work. The calculation of Dynamics and simulation show: according to the movement regularity of loading, the relationship between bearing forces and movement of platform and processing tools can be analyzed, which can provide the basis for system design and optimization.It researches on kinematic coupling characteristics for series-parallel NC machine servo system. A detailed analysis of the kinematics mathematical model is shown based on the positive and inverse kinematics analysis .Using mathematical analysis software for series -parallel institutions Newton - Euler equations, it simulated as the kinematic pair trajectory curve. Further more, the servo kinematic curve and kinematic pair trajectory curve are analyzed and compared, and the simulation results are shown that: the designed machine can run fast and smooth movement, no larger singular state and coupling errors , and it accords with relations of force and velocity kinetics.This study establishes the electromechanical coupling model of series-parallel NC machine tool servo system, and explains electromechanical coupling theory .After the establishment of the electromechanical model, it verifies the impact of coupling parameters on the system for simulation model using of software. NC machine tools for the decoupling control of series-parallel basis. It lays on the foundation for decoupling control for series-parallel NC machine tool servo system.For the problems of electromechanical coupling for servo systems modeling, using of genetic algorithm to adjust PID parameters, and strong tracking filter to solve the load disturbance and interference conditions on the system performance, it eliminates coupling factors effects for decoupling control of series-parallel NC machine tool servo system, and increases the machining accuracy and surface quality. The mechanical system and control system can be better co-ordinated, and it solves the problems that machining precision can not fully meet the requirements, low efficiency, lack of reliability and improves the performance of NC machine tools and processing efficiency. Also reference based on optimization and parameter adjustment has been provided to increase the level of debugging efficiency and production for domestic NC machine tools. The core technology of NC machine tools accelerates self-development and enhances manufacturing standards for machine tool manufacturing industry, which has far-reaching significance. |
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