The influence of topological features of sliding surfaces on the solid lubricant behaviors of carbon onions was examined. Friction coefficient and service life were measured by ball-on-disk type friction testing in vacuum using silicon disks with various fine patterns 3-50 nm in depth. Two types of carbon onions of which average particle diameters are 5 and 20 nm were prepared. As a result, lower friction coefficients and longer service lives were simultaneously observed on the disks with surface roughness similar to the particle size of carbon onions. The formation of carbon onion film several tens of nm thick was observed on sliding surfaces. This behavior was slightly more typical on the silicon disks with the pattern parallel to sliding direction, and was also observed in the friction tests using quartz glass disks.
We describe a novel manipulation technique by using localized magnetic field for manipulation of micro magnetic particles in non-contact condition. In this micro manipulation technique, soft-ferromagnetic wire that has very sharpened edge is employed as a micro electro-magnetic probe. The probe can be electro-magnetized by a solenoid wound around the probe in order to generate localized magnetic field at the probe edge. Forces of several tens nN can be generated by the electro-magnetic probe on the 1 μm diameter magnetic particle. By using the localized field, micrometer-scale magnetic particles can be selectively trapped and moved at any position on a substrate by the probe placed underneath the substrate. Chemically modified magnetic particles could be gathered at certain position on chromosome samples by using the magnetic field and adsorbed on the samples by utilizing local reaction of avidin-biotin bindings. Furthermore, the trapped micro magnetic particle was performed as a cutting tool for modification of DNA samples prepared on the substrate. The technique would be applicable in many fields such as nano and micro-scale engineering and biological manipulation.
We have developed techniques for analyzing the imaging performances of KrF exposure tools that use wave aberrations measured at 25 different image heights in a semiconductor fabrication plant. The wave aberrations are obtained by double printing lattice and square patterns and measuring their lateral registration errors. It is confirmed that multiple regression of the 3rd and 5th coma aberration coefficients permits the differences in the widths at the left and right edges of seven pairs of 250nm line and spatial patterns to be predicted to an accuracy of 9.4 nm(2σ). The results of an exposure and development simulation using wave aberrations agree with experimental results for the changes in the width of a 200 nm isolated line pattern with the focus position. This simulation is applied to quantify focus margins, which are found to be degraded due to astigmatism and spherical aberrations. Controlling the excimer laser wavelength is proposed as a means to reduce the spherical aberrations.
Assembling for miniature mechanism is used in the precision mechanics and the electronics generally. An optical fiber array is an optical communication device that consists of multi-core optical fibers and the V-grooved substrate. Because the demand for optical fiber arrays has increased, it needs the mass production of optical fiber arrays. For automatic assembling of optical fiber array, a fiber must be put in a precise position of the V-groove. In the fiber insertion to the V-grooved substrate, the trial fiber insertion system distinguished success or failure of fiber insertion using image application. The failure of the insertion depends on a bent fiber or an adsorption of the fiber. Then the system replaces a bending and an adsorption by the lateral offset and the angular offset. The system measures them with micro CCD from two directions. The effectiveness of this new distinction system was verified with 12 cores fibers.
In this study, a new design of an ultrasonic motor to expand the controllable driving speed range is proposed. Two piezoelectric elements are bonded to the metal elastic body with the cross angle of 90°. When one of the piezoelectric element vibrates at resonance frequency of elastic body, the contact point of between the motor and the carriage moves elliptically and the driving force is generated. The driving direction conversion can be easily performed by switching the piezoelectric elements. The motor have three drive modes. In the first mode (= a high-speed driving mode), the elliptical motion is provided by degenerating the resonance vibrations in X and Y directions of the metal-elastic body. In the second mode (= a low-speed driving mode), a combination of X-direction resonance vibration and piezoelectric element's original vibration is used. In the third mode (= a fine motion mode), small expansions of the piezoelectric elements with stick-slip motion are used. In this research, these three modes are combined to attain the wide range of the driving speed. As a result, the driving speed range from 10 to 500mm/s is obtained by adjusting the driving voltage and driving frequency. In the paper the principle, the design and experimental results are discussed.
In recent years, the demand of optical devices with complicated and highly accurate shape such as Fresnel lens and f-q lens is growing up in terms of miniaturization and improvement of information equipments. Moreover, the demand of glass lenses increases for the purpose of improving its heat resistance and optical performances. The study proposes a machining process for non-axisymmetric aspheric cemented tungsten carbide mold with minute structures, aiming at high precision machining. In the proposed process, the non-axisymmetric aspheric surfaces except for minute structures are at first machined by the spiral form grinding tool path with a spherical resinoid bonded diamond wheel. The machined surface center is corresponding to the center of the rotation axis of ultraprecision machine tool. Afterwards, the surfaces are ground for compensation, based on allover shape measurement interpolated by cubic spline. Then, minute structures are created on non-axisymmetric aspheric surfaces by the grinding with a disk type metal bonded diamond wheel. As a result, it is found that the proposed machining method has the potential of producing a high precision non-axisymmetric aspheric glass lens mold with minute structures effectively.
Complicated 3-D parts can be created by using the developed multi-axis control machining centers. 3-D CAD/CAM systems for multi-axis control machining are also developed to save time and labor in preparing NC data. However, operators consume a longtime in process planning since there are few practical computer systems for process planning. It is indispensable to develop CAPP(Computer Aided Process Planning) system for 3-D machining in response to the demands. The study deals with the development of fundamental CAPP/CAM system for multi-axis control 3-D machining. The system developped in the study enables 5-axis control tool path generation in consideration of tool length, the tool posture change and the workpiece fixing direction, based on the tool entrance face concept. From experimental result of creating a micro impeller, it is confirmed that the CAPP/CAM function has the potential of effective multi-axis control machining.
Glass-like carbon is expected as a die material for mold-press of optical glass devices. In this study, optimum machining conditions on electrical discharge machinability of glass-like carbon die were examined in working fluid such as oil or ion-exchanged water. Short machining time was achieved by electrical discharging in ion-exchanged water, as well as good machined surface with small roughness. This was caused by low electric resistivity of the water and a small amount of isolated carbon. Furthermore, the surface roughness of glass-like carbon discharged in ion-exchanged water was smaller than that done in oil. The glass-like carbon was suitably discharged in ion-exchanged water under conditions of voltage of 40V, electrode rotational speed of 1000∼3000rpm, pulse ON time of 5μs and duty factor of 0.3∼0.7. Under these conditions, excess melting of glass-like carbon, local discharging, adhesiveness of isolated carbon on electrode, etc. were suppressed.
The current CAM software for 5-axis controlled machining does not consider machine tool information when generating tool path. Therefore, the CAM software has the problem of outputting the tool path data that might be changed into the problematic NC data including redundant change and reversal rotation of rotational axes. In this report, the configuration space in that a position of two rotational axes indicated in one point is applied. A-star algorithm that is one of techniques for searching path is applied to decide tool attitudes considering the motion of two rotational axes in 3-dimensional configuration space. The developed method can generate tool path limiting the number of used rotational axes, and reducing the moving amount of two rotational axes. Furthermore, the method can generate tool path that avoids the reversal rotation of two rotational axes that might cause the processing error. Finally, machining experiments were performed for overhang groove shapes. As a result, excellent finished surface was actually obtained, and the usefulness of the developed method is confirmed.
This paper compares the magnitude of the electromagnetic force applied to the wire electrode during wire electrical discharge machining (WEDM) with those of other forces: electrostatic force and discharge reaction force. Both the electromagnetic force and electrostatic force were analytically obtained and found to be in agreement with those obtained from experiments. Then the discharge reaction force was determined by solving the inverse problem where the discharge reaction force was modified until the measured wire vibration agreed with that calculated using the above mentioned electromagnetic and electrostatic forces. It was found that the influence of the electromagnetic force on the wire movement is not negligibly small under rough cutting conditions, especially with higher discharge frequency and larger workpiece thickness.
This study describes a new machining strategy to make regularly aligned geometric pattern by ball-end milling process employing a patch division milling technique. The surface is divided into a lot of triangle patch segments which is machined with helical tool path. It is newly proposed the way to array cutter marks straightly in arbitrary triangle patches. In addition, it is shown that the inclination angle of cutter marks array against the feed direction can be controlled by the appropriate setting of feed per tooth and cross feed for an arbitrary triangle patch. It is shown that the experimental results and simulation results are in good agreement. It is also reported that the well arranged cutter marks arrays are formed on the triangle patches on the spherical model.
The perfect 2 degrees-of-freedom control system was previously proposed in the field of plant control. Its feature is that an accurate mathematical model is not required on application. In other words, model-free is the strong point of this control. However, though recommended values against tuning parameters are presented, its reasons are not clarified. In addition, tuning method is not identified. In this paper firstly, though the application of the perfect 2-DOF to two kind of mechanical equipments, a tuning method is experimentally cleared and derived performance is presented. Next, it is shown that the derived tuning procedure agrees with the Kitamori's method. Finally, based on the zero assignment which is created by tuning the feedforward parameters, the shaping of positioning waveform becomes obvious. Especially, under the special set of these parameters, it becomes clear that the influence due to the vibratory pole can be loose.
In this paper, a practical method of stereo vision, “subtraction stereo” is proposed. A huge number of studies have been carried out for stereo vision until now, and several practical stereo vision systems have been reported. However, what is called the correspondence problem that stereo matching becomes difficult and not robust for weak textures or recurrent patterns is inevitable for stereo vision. Subtraction stereo realizes robust measurement of range images by detecting moving regions with each camera first and then applying stereo matching for the detected moving regions. Detection of moving regions is carried out with a subtraction process. Concept and fundamental algorithm of subtraction stereo are introduced. Then measurement of three-dimensional position, height and width of a target object using the subtraction stereo is discussed. The basic algorithm is implemented on a commercially available stereo camera and the effectiveness of the subtraction stereo is verified by several experiments using the stereo camera. Although objects are restricted to moving ones, subtraction stereo gives sufficient information robustly for many applications such as surveillance.