Key Engineering Materials Vols. 589-590

Abstract: The traditional particle filter (PF) algorithm is well known for signal noise reduction processing, but it exists problems of particle impoverishment and cumulation of estimation errors. An optimized PF algorithm called RBF-PF is proposed in this paper, which uses radial basis function network for training and optimizing the process of particle filter in the sampling. Experimental analysis verifies that the new method used to gain the signal-to-noise ratio is better than traditional PF algorithm during dealing with the added noise signal.

Abstract: The flutter in the hard cutting has a significant impact on the efficiency of production, the quality processed, the environment in processing, the cost, and the life of the machines and tools . However, the application of the method named numerical simulation in MatLab predicted the stability limitation of the hard cutting system, analyzed the influence of cutting system dynamics parameters on the stability limitation of system, at the same time, an experimental verification of hard cutting had been carried out. And the results of analysis showed that improving the system stiffness K and cutting system damping ratio ζ, cutting the stiffness coefficient K_c and the direction coefficient , adjusting the cutting speed to the correct, reducing the amount of turning a_p, decreasing the tip radius of circular arc , increasing the feeding f can be used as the methods of vibration reducing in the system. So the results of the research provide reference for the reasonable choice of cutting parameters.

Abstract: In manufacturing process, reasonable tool selection can greatly improve the efficiency and reduce the cost of machining. In order to obtain optimized tool solutions, object-oriented approach to the classification and description of the machining features are presented in this paper. Machining features by means of object-oriented classes, attributes and methods are described. Efficient processing information for tool selection is extracted. Tool selection model based on the machining features is established. Cutting tool intelligent selection is implemented through rule-based reasoning. This work will help the process planners to select more reasonable cutting tools.

Abstract: In order to use magnetorheological finishing (MRF) to accomplish ultra-precision machining of complex curve surfaces, an open computer numerical control (CNC) system based on universal motion and automation controller (UMAC) has been developed. The paper introduces the hardware structure of the system, elucidates the control algorithm and parameters tuning of PID + velocity/acceleration feed-forward + notch filter, and explains the design of a friendly human-machine interface (HMI) to satisfy the need of actual manufacturing and complicated numerical control. With the open CNC system, a 4mm-diameter circle is polished on the MRF experimental prototype with the contour error of 1.67% and the surface roughness Ra of 1.4nm. Experimental results prove that the open CNC system for the MRF machine tool meets the requirements of ultra-precision machining.

Abstract: An adaptive neural network control scheme for X-Y position table is proposed by the paper. X-Y position table model is established, controller based on neutral network is used to learn adaptive and compensate uncertainty model of X-Y position table, neutral network is used to study model. Neural network parameters base on stochastic gradient algorithm can be adjusted adaptive on line. Neural network controller base on augmented variable method is designed.

Abstract: Vibration during high-speed surface grinding process is one of important factors to influence surface precision of machined workpieces and lead to low efficiency of grinding machine. Process parameters are usually obtained from empirical data or reference manuals for the avoidance of serious vibration even chatter and its effect. As a result, it generally leads to low rated power of machine tool and long processing cycle. To solve the problem, designing and development on a dynamics simulation system for surface grinding with high accuracy ,which will be capable to predict a series of dynamic characteristics in time and frequency domains, such as grinding force-vibration, as well as phase/frequency characteristics, relative power spectral analysis etc is necessary and shows good application prospect. Meanwhile, the system will be used to indicate the process parameters optimization and investigate distribution characteristics of grain chip thickness and surface topography precision. In the paper, surface grinding process with diamond wheel is chosen as the study object and its dynamic characteristics are investigated. Based on studies on the comprehensive influence mechanism of regenerative chatter theory and wheel run-out rotational model on instantaneous grinding chip thickness of grain unit, analytical models of grinding force are improved. Differential equations of damper grinding vibration system with two-degree-of-freedom and a close-loop control system model with regenerative chatter feedback circle on the basis of interaction behaviors of force and vibration are built. Several relevant numerical methods are introduced to develop the simulation system of grinding dynamics. By comparative analysis on solution accuracy, steadiness and convergence of the correlative algorithms, explicit Runge-Kutta formula is identified as the best solution to simulation system modeling. On the basis of the above work, main subsystems and functional modules in the system are presented. The whole designs of framework and prototype systems are finished.

Abstract: This paper introduces two tuning methodologies of passive vibration absorbers named equal peaks method and equal troughs method respectively. By studying on the model of dynamic system, the optimal parameters are obtained. Furthermore, the results obtained by one method are compared to another one, and vice versa. The results show that the tuning methodologies have their own advantages and should be selected according to the industrial requirement. In the end, the responses of two methods to the excited force are compared in the time domain with Matlab.

Abstract: Large volume cubic anvil (LVCA) have been widely used in cubic high pressure apparatus, which can accommodate a large sample volume (the largest volume of compressed cell is 422 cm3), but they are limited by shorter lifetime (£143000 times) and lower cell pressure (£146 GPa). In this paper, we have designed of a double radius type LVCA, which has three advantages. Firstly, the rate of cell pressure transmitting and the pressurized seal stability of the sample cell can be maintained, which is often sacrificed with optimum the geometrical condition of the anvil. Secondly, the lifetime of double radius type LVCA can be increased about 19.86 % than that of traditional anvil. Thirdly, the cell pressure can be increase about 13.45 % after the modification of the anvil. This work makes an effective solution for solve the choke points of LVCA and would be used widely in other types of Multi-anvil apparatuses.

Abstract: Aiming at there are multifarious small shaft and sleeve subassemblies, in which shape and quantity of parts are different, the adaptable design concept was applied to the design of auto assembly machine product platform for small shaft and sleeve subassemblies. According to the general structure design and the module partition for the product platform, a parameterized design method that the number of stations is the main parameter was proposed. And the parameterized product platform, which can be suitable for the automatic assembling of multifarious small shaft and sleeve subassemblies and can be upgraded, was founded. Thus, the universality of the product platform is improved, and the product design cycle is shortened.

Abstract: This paper provides the transfer matrix method to analysis the natural frequency of the vertical spindle using on ultra-precision fly cutting machine tool. Several transfer matrix equations of the typical units of the spindle had been established when considering the effects of the gyroscopic torque as the rotor has a large inertial tensor. And then the natural frequencies and each modal shape of the spindle rotor system were calculated using the transfer matrix model. Also, the modal experimental test had been taken out. The theoretical results from the transfer matrix model are very close to the test results, and the accuracy and the effective of the model was proved.