We have successfully demonstrated a method to produce glass nanoparticles by a continuous-wave (CW) CO₂ laser beam. Three types of glass composites were selected and generated glass nanoparticles exhibit lower melting temperature compared with bulk glass. To understand the mechanism of those particle size variations, we have simulated glass temperature and discussed on the strong relationship between glass transition temperatures and melting temperature of generated glass nanoparticles. Regarding melting temperature of glass particles, we investigated the cooling speed, fictive temperature of particles and the effect of the diffusion of water from increased surface area. Ejected particles collected were analyzed by scanning electron microscopy to determine particle sizes and evaluated the melting temperatures by differential thermal analysis. The measured mean particle diameters were 38, 141 and 222nm, and the differences of melting temperature between bulk and nanoparticles were 162, 46 and 3°C respectively.

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5-axis control machining can realize high performance machining by considering the relative attitude between a tool and a workpiece. Thus, it enables to avoid the abnormal tool wear and the deterioration of machined surface quality. The influence that the tool attitude gives the machined surface has been investigated by some researchers, and the tool attitude to obtain good surface quality has been already proposed in previous studies. On the other hand, the tool attitude in 5-axis control machining cannot but change inevitably with the rotational axis motion, while keeping the relative attitude constant. The influence of not only the tool attitude to the machined surface but also the variation in tool attitude should be evaluated to obtain good surface quality, based on 5-axis control machining experiments. The study deals with the proposal of an evaluation formula by considering the influence of both the tool attitude and the variation in tool attitude. It is experimentally recognized that the devised CAM system can generate appropriate 5-axis control tool paths for finish machining by utilizing the evaluation formula.

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Polishing is commonly used to attain high flatness and smoothness for silicon wafers and rectangular glasses. A flatness of better than 10 μm is required for large quartz masks to transfer fine patterns. A backing pad is usually used to hold the workpiece during one-sided polishing. However, it is difficult to fabricate a nonwarped mask by this method. Therefore, a nondeforming freezing pin chuck has been developed. This paper describes the principles of the nondeforming chuck and the process used to manufacture a nonwarped substrate. The temperature distribution in the chuck, the droplet profile and the shear peeling strength of the freezing liquid are investigated. The temperature distribution of the freezing pin chuck is calculated by the finite element method using an axisymmetric model. The results reveal that, for a polishing temperature of less than 30°C, use of a coolant at 5°C with a heat transfer coefficient of 1000 W/(m²·K) can reduce the temperature on the back surface of a quartz substrate to below 15°C for a substrate that is over 2 mm thick. The freezing liquid has a contact angle from 20° to 40°, which is much smaller than that of water. Consequently, the pin must have a diameter of over 0.73 mm. The average shear peeling strength of the freezing liquid is improved from 37 to 80 kPa by lapping the pin top. Based on these results, a freezing pin chuck with a pitch of 2 mm and a pin diameter of 0.8 mm was designed for polishing applications.

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Recently, a new method of quickly evaluating the machining accuracy of 5-axis machining centers has been proposed, and named this method ‘groove-matrix machining’. This method requires machining each sets of grooves arrayed in a matrix on a test piece mounted on a tilting rotary table, with its tilt or rotation angle changed. Under these conditions, machining accuracy can be evaluated from the test results. In our previous paper, however, the capability of estimating geometric errors inherent to 5-axis machines was not discussed when using groove-matrix machining. This paper proposes the use of ‘groove-matrix machining’ as a method to estimate the geometric errors from the machined workpiece, and confirms its effectiveness.

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Robotic cellular manufacturing systems are a new type of manufacturing system in which one or more flexible robots carry out a large number of assembly operations that would be performed by people in conventional cellular manufacturing systems. The conceptual design stage, when the assembly system layout details are decided, is especially important during the development of effective robot cellular manufacturing systems, since fundamental performances of the system under consideration are determined at this stage. Since development of a decision-support system for the conceptual design of robot cellular manufacturing systems would streamline decision making, this paper proposes a layout design optimization method for robot cellular manufacturing systems. First, the design criteria for robot cellular manufacturing system layout designs are clarified, and objective functions are formulated. Next, layout design candidates are represented using a sequence-pair scheme to avoid interference between assembly system components, and the use of dummy components is proposed to represent layout areas where components are sparse. A multiobjective genetic algorithm is then used to obtain Pareto optimal solutions for the layout optimization problems. Finally, several numerical examples are shown to illustrate the effectiveness and usefulness of the proposed method.

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In the current manufacturing practice, injection molding is widely used for fabricating plastic parts of various consumer products, such as digital cameras, printers and other electric appliances. In designing a plastic part, thickness of the part is defined to be constant all over the surface, otherwise some deformations happen in the molding process which deteriorate the aesthetic quality of the product. In this paper, the authors propose a fast algorithm for evaluating the thickness of the solid model. Existing commercial CAD systems provide some thickness measuring functions of solid models. These functions are, however, not appropriate for evaluating thickness of the complex shape. In this paper, a new definition of the thickness of the solid model is proposed. Using the definition, a fast thickness evaluation algorithm with the oriented bounding box (OBB) and the parallel processing capability of GPU is developed. A system is implemented and some computational experiments are performed.

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This paper describes a new approach to sub-pixel edge localization by fitting a 3rd-order polynomial surface around each edge point using third order Taylor series expansion and correction with curvature.Sub-pixel edge location is then found as the zero-crossing of the second derivative along the gradient direction across the edge.The zero-crossing of the second derivative along the gradient direction has the same location as the peak of the first derivative.We further propose a new formula to correct the bias to curved edges based on the curvature.The experimental results show that sub-pixel location is unbiased against image noise in the case of straight edges and proposed method has high precision in both simulation images and real images.In the case of straight edges,accuracy of less than 1 twentieth of a pixel can be achieved.

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Shock acceleration measurement is widely carried out in a variety of applications such as air-bag control of automobiles or drop testing of mobile instruments, in which accelerometers are a key device to evaluate human safety or product reliability. However, despite the fact that accelerometers have the non-linear sensitivity in relation to frequency and acceleration level, many Japanese private laboratories calibrate accelerometers by the means of comparison calibration in which each reference is traceable to different oversea national standards. Since it is difficult for comparison calibration to evaluate the non-linear characteristic, we developed the shock acceleration calibration system with Japanese time and length standards for primary calibration. In order to enhance the reliability of shock acceleration measurement, it is essential to confirm the equivalence of accelerometer's calibration results between primary and comparison calibrations. So, a round robin test was executed among the National Institute of Advanced Industrial Science and Technology (AIST) and the three Japanese private laboratories. The calibration results among the four laboratories were matched within a difference of 0.17% and En value of 0.58. Also, the non-linear characteristic did not affect the calibration results on the experimental condition of this round robin test.

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