Advanced Materials Research Vols. 694-697

Abstract: According to the difficult problems in wire cut electronic discharge machining (WEDM), a NC rotary table was designed and its mathematical models of spatial complicated curved surface were established. Through the processing experiment of the Octahedral Pagoda, the designed WEDM system was used to process the test piece to verify the correctness of the processing model. It shows that the designed NC rotary table reaches the requirements in shape and dimensional accuracy to prove the correctness of the processing to provide a useful reference for the follow-up study of machining the spatial complicated curved surface parts.

Abstract: The effect of geometric error on machining accuracy was researched by multi-body system theory, as well as homogeneous coordinate transformation method. Taking a vertical machining center as example, topological structure of the machine tool was described by lower body array. Lower body array of the machining center, motion freedom between adjacent bodies and geometric errors of the vertical machining center were analyzed. Geometric errors of the bodies in the multi-body system were expressed by homogeneous coordinate transformation. Error model for machining accuracy was deduced and geometric errors having influence on the machining accuracy were identified. The research results provide guidance for analyze of geometric errors on machining accuracy.

Abstract: In order to get over the limitationof the velocity planning method of computerized numerical control (CNC) system,a rapid S-shaped acceleration and deceleration method is presented in thispaper. In the method, the rapid solving model of S-shape velocity planning isproposed, and these displacement, velocity and acceleration formulaeof a rapid S-shape acceleration and deceleration model are derived. Compared with the proposedapproach and the traditional velocity planning method, the simulative and experimental resultsshow that the proposed method is smoother, and the machining efficiencyis greatly improved.

Abstract: In order to overcome thelimitation of the position servo control method of computerized numerical control(CNC) system, a control approach of generalized predictive control (GPC) ispresented in this paper. In the method, the GPC model calculates the optimalcontrol rate through the predictive model and rolling optimization as thecontroller of the position servo system. Compared with GPC and proportional-integral-derivative(PID) control, the simulative and experimental results show that the proposedcontrol approach has better the dynamic performance, steady-state performance,and robustness.

Abstract: The precision of high-speed CNC (Computer Numerical Control) machine are greatly influenced by the dynamic characteristics of servo system. In this study, by investigating the motor of the servo system of CNC machine, an inertia and damping linear identification model is established using current as input signal and motor rotation velocity as output signal. Moreover, the excitation signal generation method based on G-code, concerning the closed-loop identification of servo system, is proposed. Furthermore, to verify the effectiveness of the closed-loop identification, an experiment is carried out on the feeding system of a commercial NC machine. The experiment results show that the proposed method performs well with effective stimulation, rapid convergence and accurate results.

Abstract: Current signal can reflect the cutting state of the machine tools effectively. Two-dimensional fuzzy control strategy is introduced to realize the cutting current changing smoothly. With the current value used as the system input, segmented membership functions are constructed to satisfy the sensitivity and stability requirements. To verify the control system, an experiment is completed with the application of Matlab-simulink. The experimental results show that the fuzzy control strategy can not only effectively reduce the fluctuation degree of current but also highly improve the stability of the NC machining system.

Abstract: The quality of high-speed machining workpiece is determined by drive control performance of motorized spindle. Vector control is one of high-speed motorized spindle control method, but the traditional controller is difficult to effectively overcome parameter disturbances caused by parameter variations from internal and external system. So it is necessary to use intelligent control. In this paper, a model of a speed and flux-closed-loop vector control system with an inner torque-closed loop is established, and a fuzzy controller is used to adjust the speed. MATLAB is used for load simulation of high-speed segment of motorized spindle, and then the simulation results show that high-speed motorized spindle can be increased in to the high-speed segment using a short period of time, and it has strong anti-interference ability and excellent performance at the same time in the control system presented in this paper.

Abstract: The information processing is an effective approach to realize the characteristic of the precision positioning stage. The analysis and comparison between the normal location data and the location data with oscillation reveal the frequency response of the source which causes the oscillation. The compensation efficiency of the control system is explained by the spectral analysis of the compensating command and real-time feedback displacement.

Abstract: In order to avoid the problem of tool destroyed and machine damaged because the NC (numerical control) system appeares tool identification error in the tool changing process, in the paper, the author constructed a based on RFID(radio frequency identification) technology tool changing model of the numerical control system. It can improve the tool's high reliability recognition, shorten tool changing process time and reduce the failure rate. it can realize RFID equipment and tool management information system integration that the tag sticked in the tool of the NC system is regarded as information identification basis. The author analyzes automatic tool changing process based on RFID, constructs the system hardware platform and designs software.

Abstract: According to the traditional application of the artificial projection method to escape wheel detection, this paper proposes a new method based on digital template, after the introduction of the working principle and advantage, emphatically discuss the algorithm design. The experimental results demonstrate the proposed algorithm has high real-time ability, good reliability and more suitable for practical engineering application.