Key Engineering Materials Vols. 407-408

Abstract: PRS-XY hybrid NC machine tool is a 5-degree-of-freedom cutting machine, which is composed of a 3-degree-of-freedom parallel mechanism and a 2-degree-of-freedom series mechanism, and can be applied to machining and testing of machine parts with complex surface. In this paper, the kinematics principle of the machining tool is analyzed, and the kinematics model for calculating the location of the real control axis is deduced. Through the cutting experiment of a typical part, the kinematics principle of the PRS-XY hybrid machining tool is validated, and the results also indicated that the machining tool has the multi-coordinates machining ability and preferable machining precision.

Abstract: To design a machine tool successfully, its essential parts should be analyzed and evaluated after design but before prototype being made. The spindle assembly is one of the most essential parts of high speed machine tool, so how the dynamic characteristics of the spindle assembly affect the performance of high speed NC machine tool are of great significance and should be studied. This paper’s research is based on a high speed machine tool manufactured by some plant. The finite element analysis model of the spindle assembly of the high speed machine tool was developed by taking the advantage of the spring-damper element to simulate the bearing supports. The modal analysis was made to confirm the dynamic characteristics of the spindle assembly, and the results were compared with the testing ones.

Abstract: It were researched that the modeling methods of machine accuracy and the control techniques of the error compensation based on BP neural network(BPNN) for parallel machine tool(PMT)with five degrees of freedom(DOF). The samples are obtained to train the BP neural network which has good capacity for non- liner mapping, learning and generalization. The machine accuracy mathematics model is established for the error compensation, in order to study the nonlinear input and output problem of the parallel machine which difficultly modeling described. The trained neural network was applied to error compensation of PMT to realize modifying errors real-timely. Finally, simulation analysis was performed through the MATLAB software. The results expressed that the control strategies for error compensation were simple, efficient and practicable. Machine accuracy can be increased greatly after compensation.

Abstract: The prototype of a new 3-DOF tripod parallel universal wrist was developed. Its structure, characteristics and applications were introduced. The inverse kinematics model was established by the vector and kinematics influence coefficient method. The schematic diagram of simulation was established through the software — MATLAB/Simulink. Based on the above model and diagram, the inverse kinematics simulation was made. The simulation curves under different initial conditions about angle, acceleration, velocity, displacement varying as time processed can intuitively reflect the kinematic relation between the parallel bars and the moving platform of this mechanism and this is valuable and significative for the further research.

Abstract: Analysis on the singularity of the 3-RPS parallel machine which probably occurs in the engineering application is presented. The influence of the singular configurations in the workspace of the parallel machine is interpreted. To improve the orientation capacity of the moving platform, a novel complex spherical joint is designed, however a special singularity namely coaxial singularity is resulted in. By optimizing the dimension parameters and designing a special moving platform, the singularity can be averted in the wanted workspace, and the nutation angle of the parallel machine can be enlarged to ±45 degree.

Abstract: In this study, covering for the skill training centers in Japan, we performed surveillance study about the functions required for the general purpose milling machines for educational skill training. As a result, it was found that the function of recognizing machining state is desired for milling machines besides higher stiffness, higher accuracy, and the ease of chip treatment. Based on this fact, the general purpose vertical milling machine was developed for educational skill training. First, a beginner's work analysis was conducted and the functions which control the mishandling were developed. The operation mistake has decreased by this function. In addition, the cutting power inspection system was built by using high sensitive micro-wattmeter. And, the possibility of judgment of tool wear was found by inspecting the change of the wave profile in the wattmeter.

Abstract: One novel long-travel piezoelectric-driven linear micropositioning stage capable of moving in a stepping mode is developed. The stick-slip friction effect between flexure hinge actuation tips with a sliding stage is used to drive the stage step-by-step through an enlarged displacement of piezoelectric actuator. In order to enlarge the travel range, magnifying mechanism is optimally designed by use of flexure hinge and lever beam. Moreover, dynamic model of such stage is proposed by consideration of reset integrator stick-slip model. The simulation results show that the stage has considerable good dynamic properties.

Abstract: As the key parts of cars, camshafts influences a lot on the quality and durability of cars. Their processing is complicated, time and place consuming and the quality is difficult to guarantee. The turning-grinding composite machine tool (TGCM) for camshafts is studied on basis of ‘process integration with one setup’ theory in this paper. It presents the structure of the turning-grinding composite machine tool by the analysis of the function of TGCM. The revolving working table is used to transfer the turning and grinding function. It also discusses the constant grinding removal rate mathematic model of the cam contour machining. The opened-CNC system for this machine tool is developed by using the VC++6.0 based on PC and UMAC controller. The constant grinding rate model of the cam contour is verified by the experiment results.

Abstract: Combining the research and development of dual mass flywheel, the paper explores the realizing methods of CAD/CAE/CAM integrated design system. The system is composed of modules including digital structure design and simulation, entire-car NVH analysis, analysis and optimization of formation process and welding process. Based on PDM technique, data sharing and integration could be realized through corresponding interface procedures by establishing a uniform product data model. The paper studies on the digital structure design and simulation, torsional vibration analysis, sheet material forming technology simulation and welding technology simulation. Finally the paper shows the comparison between one type of dual mass flywheel sample test curve and simulation curve.

Abstract: Virtual numerical control milling simulation system, based on UG, is studied oriented to low utilization of NC machines. A virtual machine tools library, standard fixture library and visual machine tool processing environment were established by the second development techniques of UG and VC++. Through the example of XH715 NC machine center, tool path and motion of miller were simulated separately; at last processing scheme was evaluated and optimized. The experimental results show this system possesses good utility, and the utilization of machine tools could thus be improved.