Advanced Materials Research Vols. 189-193

Abstract: The original grating is etched by using the nanometer etching function of Scanning Probe Microscopy (SPM). There are five grooves etched on the surface of polymer material. The grating constant is 796.87 nm, so the fringe density is 1254 lp/mm. Diffraction pattern of the original grating is obtained on Michelson interferometer. A new method of making original grating is found. Since the Nominal Tip Radius of Curvature (NTRC) of Etched Silicon Probe (ESP) of used Veeco SPM is 5-10 nm, the etching grating should have fringe density of 50 000 -100 000 lp/mm.

Abstract: An experimental method using a specifically set-up is presented in order to investigate dry friction phenomena, which occurs in the cutting process at the tool chip contact, in a wide range of sliding speed. A ballistic set-up using an air gun launch is used to measure the friction coefficient for the steel/carbide contact between 15 m/s and 80 m/s. A series of tests are conducted according to the sliding velocity and the normal pressure. These measurements are also introduced in a finite element simulation. The focus of this work is to determine the relevance of the friction modeling in the finite element method of the high speed machining. Modeling results are compared with cutting forces measured on a similar experimental device, which can reproduce perfect orthogonal cutting conditions. Measurement of temperature fields during the cutting process complete the parameter required for modeling. The results show that in high cutting speed, the friction modeling usually used in the FE codes is limited and that novel formulations are needed.

Abstract: Al/SiCp composite material is rapidly advanced due to its applications to weapon, military, aeronautics and astronautics. In some cases, fields of research are stagnating for its difficulty in material processing. In this study, we are particularly concerned about the cutting mechanism of Al/SiCp through modeling and simulations on wear rate of the tools. These simulations of tool wear rate and cutting mechanism of Al/SiCp are proved by cutting tests on Al/SiCp with nanocemented carbide tool WC-7Co and common cemented carbide tool YG8. A detailed investigation suggests that the cutting instinct of Al/SiCp is of interrupted cutting process. And the grain loss, less tipping and blade fracture during tool wear results from high frequency intermittent shock by SiC grain. The wear behavior on the tool flank is mainly of grain loss. However, the wear behavior of the rake face is not only of grain loss, but also abrasive wear of WC grain by SiC grain. It is conclusively demonstrated that the model of tool wear rate is sufficient for revolution characterization of tool wear rate on grain size, volume fraction of reinforcement, and also significantly important to prove the interrupted cutting process mechanism of Al/SiCp.

Abstract: This study attempted to design and develop an integrated system of a microforming apparatus with ultrasonic-vibration device. A closed-loop displacement and force control was implemented with servo motors. The apparatus has a load capacity up to 10,000N. The displacement error curve of the platform was measured with API 5DLS laser interferometer, and fed into the control program to compensate for motion errors. The positioning precision of the platform has been upgraded up to 5μm, with a load accuracy of 0.5N. Taking advantage of FEA and optimization technology, boosters and resonator with 35 kHz frequency were designed and fabricated. The simulation results and the experimental results match perfectly on the account of resonance frequencies and amplitudes. To the end, the integration of the ultrasonic-vibration device with microforming platform demonstrates a precision process for micro-parts.

Abstract: Noncircular turning is necessary for machining various irregular shaped workpieces. Tool positioning control is essential for a noncircular turning system. This paper proposes a method of accurate tool positioning based on piezoelectric ceramics micro-displacement actuator. A Duhem hysteresis model of piezoelectric actuator has been developed, together with a control model of accurate positioning system. By using Simulink/Matlab, the control system was simulated, and then tested on a test-bench. The results show that the positioning time of control system is 0.1 seconds and the error rate of positioning accuracy is less than 5%, which can meet the accuracy positioning requirements of the noncircular turning system.

Abstract: In this paper the relationship of the efficiency of ultrasonic grinding and abrasive movement are studied. Ultrasonic grinding grain three-dimensional trajectories were simulated based on MATLAB software in the paper, and micro-grinding surface states were observed with SEM. Therefore, the influence law of ultrasonic vibration to the grinding surface texture is received. The results show that: Compared with ordinary grinding, the workpiece grinding surface texture quality and the grinding efficiency have been significantly improved under the condition of ultrasonic vibration.

Abstract: Abrasive machining is a widely employed finishing process for different-to-cut materials such as metals, ceramics, glass, rocks, etc to achieve close tolerances and good dimensional accuracy and surface integrity. High speed and super-high speed abrasive machining technologies are newest developed advanced machining processes to satisfy super-hardness and difficult-to-machining materials machined. In the present paper, high-speed/super-high speed abrasive machining technologies relate to ultra high speed grinding, quick-point grinding, high efficiency deep-cut grinding were analyzed. The efficiency and parameters range of these abrasive machining processes were compared. The key technologies and the newest development and current states of high speed and super-high speed abrasive machining were investigated. It is concluded that high speed and super-high speed abrasive machining are a promising technology in the future.

Abstract: Groove pads are used quite widely in chemical mechanical polishing (CMP), and groove size plays an important role in CMP characteristics. This study focuses on the investigation of the groove size effect using X-Y groove pads which are different with pitch and width. The first experiment shows the size effect on the polishing characteristics including material removal rate (MRR), within wafer non-uniformity (WIWNU) on 4 inch oxide blanket wafers for 60 seconds. The second experiment verifies the reason why MRR and WIWNU are different, by the calculation of slurry duration time (SDT) resulting from the change of friction force. All experimental results indicated that a significant difference of slurry flow attributed to groove width and pitch has an impressive influence on friction force, finally the MRR and WIWNU are affected by the groove size.

Abstract: In order to decrease the influence of installation eccentricity on gear error evaluation and to raise its accuracy, a compensation algorithm for installation eccentricity is proposed and a compensation model of installation eccentricity is established. A new installation eccentricity parameter identification method determined with involute equations is also raised. Installation Eccentricity parameters are gained through measuring points on involute profile with the method of unconstrained parameter identification. Taking involute profile evaluation as an example, the eccentricity compensation model is introduced into the error evaluation of CNC Gear Measuring Center. The experiment shows that the compensation model raised in this paper can compensate for evaluation results of the involute gear whose eccentricity value is within 2/3 of the total measurement range of the probe and lead it into the non-eccentricity condition, and the most installation eccentricity value that can be compensated in the experiment is 300 μm. The proposition of this compensation method not only improves the accuracy of gear evaluation, but also lowers the requirements on installation accuracy of the gear.

Abstract: In this study, a novel sensorless control to yield sub-micron precision positioning performance and low cost has been introduced to a Sawyer motor-based two-axis planar motion stage. The experiment results have verified the effectiveness of the suggested strategy for the stage.