Materials Science Forum Vols. 697-698

Abstract: This paper proposed a pipeline based reconfigurable architecture for CNC controllers. The architecture consists of an upper controller and a NC Microcode Processor (NCMP). The control software in the upper controller is a multi-thread program, including a management thread and a NC pipeline thread. The NC pipeline thread in the upper controller converts the machining program into NC Microcode (NCM), which is optimized for the real-time execution in NCMP. A pipelined feedrate plan algorithm is developed for the proposed architecture. The algorithm features a reconfigurable structure and look-ahead ability for high speed machining. Two prototype systems were built to demonstrate the feasibility of the proposed architecture. The experimental results indicate that the NC pipeline is highly reconfigurable and flexible in design compared to the classic implementation.

Abstract: The necessity for skull patch surface for cranioplasty was introduced and it was divided according to maximum normal curvature in the discrete points after skull patch surface dispersed. Then the tool axis vector was determined by the lead angle of the tool, corresponding to generating the tool path in each area; At last, the implant shaping mold for cranioplasty was produced by five-axis NC machine.

Abstract: The article studies on the processing program of Logarithmic spiral internal gears face with features of CNC linear cutting machine which can be easily used in processing complex parts to produce qualified products and to apply non-key surface connection into the production.

Abstract: This paper proposes a multi-step and multi-probe method to measure the roll error of a linear worktable during its movement. Two displacement sensors are used and two measurement steps are employed. Compared with two displacement sensors and a sensing target with high flatness method or a method using autocollimator, this method is in low cost and easier to be carried out. In proposed system, the slope information of roll error is obtained by sensor fusion technology. Roll error estimation algorithm is derived, and sequential-two-point method is used to sample sensors’ signal. Simulation and experimental results show the feasibility of the proposed method.

Abstract: Based on the virtual instruments technology, a data acquisition and pretreatment system for monitoring the thermal signals of the spindle of machine tool is suggested, and the temperature rise and thermal distortion signals are collected synchronously. The software of the system introduces Producer/Consumer pattern to improve data sharing and buffered communication between data collecting and data storage processes, by this means, data missing and iteration are avoided, although these two processes run at different rates. At mean time, Matlab Script interface technique is utilized to realize the hybrid programming of Matlab and LabVIEW, which makes the acquisition system possess the ability of accomplishing complex algorithm.

Abstract: Designs of free-form surface products are becoming increasingly complex. In traditional three-axis machine tool machining, errors that are caused by repetitive positioning and the costs of fixture jig design and manufacturing are critical. Since multi-axis machining provides two more rotational degrees of freedom than a three-axis machine tool, the former can solve these problems, and has therefore become the trend of precision cutting. As multi-axis machined parts often have holes and grooves on the tilted plane, this work proposes a method for machining tilted working plane features and for NC generation on a five-axis machine. The developed module can provide common geometric features, allowing the user to alter the machining feature and sequence on the tilted plane quickly using the parent-child relationship in a tree diagram, and plan the tool path. The postprocessor module developed in this paper can transform the tool path into an NC program required for machining. Finally, solid cutting simulation software is utilized to confirm the feasibility and correctness of the tool path and NC data of the tilted plane machining feature.

Abstract: There is great practical significance in error compensation of CNC machine tools. In this dissertation, the measurement theory and application methods of some advanced measure were analyzed. From those measurement methods, we found the drawback of comprehensive error measurement. Further more, this paper has detailed a new defined as single-measurement for the sake of the double-frequency laser interferometer to measure 14 geometric errors of three-axis system. The method facilitates measurements and shortens the machine shutdown time.

Abstract: This paper provides the methodology on analyzing the dynamic characteristic of machine tool in consideration of joint parameters. To ensure the dynamic model is available for further study, modal experiment for vertical machining center is involved. The machine tool is divided into several parts and connected with spring and damping for substructure modeling. Particularly, the bolt-fixed joint is an example for the joints modeling. Based on the dynamic model, simulation of modal analysis and harmonic response are carried out. Besides, method of optimization design of column and milling box is given to improve the performance, which is proved to be feasible in harmonic response.

Abstract: Microbial pretreatment was applied to enhance biogas production from corn stover through solid-state anaerobic digestion, but the price of microbial strains is high. The objective of this study was to find the effects on biogas production by the naturally microbial pretreatment method. The highest cumulative biogas yield for 60-day solid-state anaerobic digestion was obtained in B group (the pretreated corn straws with cow dung), which was 19.6% higher than that of the untreated samples. The D group（the pretreated corn straws with the sludge）cumulative biogas yield for 60-day solid-state anaerobic digestion was obtained, which was 18.87% higher than that of the untreted samples. The biogas of D group increased to the range of 55%～60% methane content, while B group with the range of 75%～80%.The results indicated that the pretreated corn straws mixing cow manure can improve both the biogas production yield and the content of methane in CH_4。

Abstract: The impact force of micro-detonation of striking arc machining is studied. The orthogonal experimental design and regression analysis method are employed to build the prediction model and the influencing laws of processing parameters on impact force are educed. Experimental results show that the impact force decreases with the increment of working current and increases with the growth of working pressure and nozzle diameter. The exponential type model is consistent with experiment results. The research can offer an important reference for the process control of micro-detonation of striking arc machining.