Drilling of crystalline silicon with a laser beam emerged from an as-cut glass optical fiber in wet etchant has been investigated in this report. This method enables deeper drilling than conventional laser drilling methods such as focusing a beam with a lens, because the beam can be delivered to the bottom of the hole by inserting the fiber in the hole. KOH based solution was used for the etchant and H2O2 was added to it in order to prevent the etching of the non-irradiated area. A CW Ar laser and a frequency doubled pulsed Nd:YLF laser were compared. Through-hole drilling of the wafer (0.5mm thickness) was investigated using different types of laser source. The average powers of the lasers were 10W. With the Ar ion laser 40 min. irradiation was needed to perforate the wafer and the hole was cone-shaped. On the other hand, with the Nd:YLF laser, through holes were drilled in less than 1 min. of irradiation and the hole had a smoother and sharper wall than with the Ar laser. No damage was observed on the optical fiber. Through holes were also drilled on 3mm-thick wafers.
This paper deals with a three-dimensional (3D) fractal analysis of wear process of cutting edges in cBN grinding. Wear behavior of grain cutting edges in the grinding process with vitrified cBN wheels has been observed using 3D-scanning electron microscope with four electron probes and the 3D surface profile of cutting edge has been evaluated by means of the fractal analysis. Wear mode of cBN grain cutting edges can be characterized by the fractal dimension. The fractal dimension for the surface profile of cutting edge formed by brittle attritious wear is higher than that of cutting edge formed by ductile attritious wear or fracture wear. Therefore, an increase in ductile attritious wear flat on the grain cutting edge results in a decrease of the fractal dimension. In addition, the complicated changes in shape of cutting edge due to self-sharpening can be evaluated quantitatively by the fractal dimension.
The vibratory linear micro-feeder has developed to feed a difficult handling object as a micro-parts, a soft or membranous materials. Its track and spring strips are united by bending as continuous member, only the shim plate with bimorph type piezoelectric actuator. Then, the construction has the most impotant conditions. The first, it is easy to carry out the production, because, sensitivity for dimensions is low, that is lightly affected to manufacturing errors. And the second, structure of the feeder can be simplified. By giving an eye to fundamental mode of flexural vibration, dynamic deflection of the track can be suppressed, and is sufficiently smaller than horizontal amplitude even if flexural rigidity is not high. Therefore, it is possible for a simple micro-feeder as the micro-mechanism to be realized without assembly of many parts. The dynamic deflection can be reduced by higher rigidity of the bended corner at both track ends in the case of a long track. On the other hand, lower rigidity of the corner is more suitable for a short track. In the first trial, the normal feeding of the 1608 tip capacitor has sucessed by the thin track consisted of the shim plate and aspect ratio 2, length ratio of the track to the actuating member. Feeding of a hydrophilic gel, the most difficult feeding object, was realized by the specially devised plane with water of the suitable quantity.
This paper deals with a new calculation algorithm of Z-map representation with graphics hardware to perform geometric simulation of NC machining process. Graphics hardware (GPU) is a device designed to render 3D computer graphics. In previous studies, it is proposed that shape of machined workpiece is estimated by referring depth information on rendered image by GPU. However, such depth information usually contains calculation error that cannot be corrected, because GPU cannot deal with curved surface directly and requires approximation to a polyhedron. In this paper, a new geometric calculation method based on GPU functions is proposed in order to estimate accurate depth information from rendering process. In the proposed method, pixel shader in GPU estimates a distance between the curved surface and the approximated polyhedron in modeling coordinate system and corrects the depth information on frame buffers.
A new three-axis FTS system has been developed for ulrtaprecision machining. The 3-axis FTS unit can drive the cutting tool freely in the space by controlling the motion of the three piezoelectric actuators arranged along the three axes of the orthogonal coordinates. In order to carry out elliptical vibration cutting with the FTS unit developed, sinusoidal vibration commands are added in two directions. In this report, two methods are developed to generate the vibration command, one is to use the controller as the signal generator, and the other to add the external command signal. Series of micro groove cutting tests were carried out on Ni-P work with use of single crystal diamond cutting tool. It was proved that fine grooves without bur formation were generated by adding the circular vibration to the cutting tool. The V-shaped micro-groove array with flat ends was also machined successfully.
Fine and precise machining are required in various industrial sectors. The tool with high durability and reliability for such machine process is almost made of hard and brittle materials, and it is generally unmachinable. The focused ion beam (FIB) machining is one of the most promising nano-machining technologies for machining of hard and brittle material. In this study, surface hardness and surface roughness of hard and brittle material after machining with FIB are discussed. Covariance structure modeling of the nano-machining process with FIB results in connections between machining conditions and irradiated material characteristics. The results show that the increasing beam diameter prevents the decrease of surface hardness and the increase of surface roughness after the machining with FIB.
Demands for ultra-precision machined surface such as semiconductor wafer are rapidly growing. However, shrinking design rules of the semiconductor reduce process yield in manufacturing line. One of the biggest factors of the reduced yield is a nano-defect on the large area surface, so we must develop a defect measurement system with higher resolving power, throughput, non-destructiveness and robustness. Therefore an optical method with higher resolving power beyond the Rayleigh limit is required. In order to develop an optical inspection system with high resolving power, we have proposed the application of the structured light illumination (SLI) microscopy for the defect measurement of the ultra-precision machined surface. It is expected that the resolving power of the system exceed the Rayleigh limit by the SLI, and the robustness is enhanced by a image reconstruction algorithm using multiple images with shifts of the SLI. In the first report, to verify the resolution property of the method, we carried out theoretical examination and the computer simulation. As a result, the proposed method makes it possible to observe a structure with robustness and higher resolution beyond the Rayleigh limit and it is suggested that this method is available to measure defects on the ultra-precision machined surface.
The measuring system for evaluating the accuracy of a deep hole is developed by using the autocollimation principle. The system consists of a measuring unit and an optical system for light reception. The measuring unit comprises one laser diode, two mirrors, two quarter-wave plates, one polarizing beam splitter, and a feeler. The system detects the displacement of a feeler on the basis of the autocollimation principle. The optical system for light reception, which receives the laser beam irradiated from the laser diode in the measuring unit, comprises a plano-convex lens and a CCD camera. In this research, the measuring unit is manufactured for trial and its measuring accuracies are examined by using the basic experimental apparatus. As a result, the followings are clarified. The optimum values of the CCD image processing parameters are 60 in threshold and 250μs in exposure. The error of measurement by using the measuring unit is ±0.26 μm. Measurement error of its rotational angle is ±0.01°.
Bicycle is high efficiency vehicle and suitable for an improvement of environmental problems from society's perspective. In the practical use, however, it has some demerits. For example it is not always stable. Therefore the motion stabilization is required, and it is necessary to improve the stability of bicyle. This paper proposes a self-sustaining control strategy of electric bicycle motion using acceleration control based on backstepping. In particular, this technique is useful for improvement of running stability in low-speed range. The validity of the proposed method is confirmed by numerical and experimental results.
In a high quality machining-assembly production system applied a corrective assembly approach, a measurement error, which occurs in measuring a processing error of assembly part, causes an incorrect allocation of reprocessing machines and reduces a production rate of high quality assembly products. In this paper we consider a method for maximizing the production rate of assembly products which consist of two assembly parts and satisfy a predetermined assembly tolerance. In this method two optimal parameters are searched in order to maximize the production rate: one is a range of measurement assembly error which determines how to select a correct reprocessing machine and another is an adjustment size of each reprocessing machine. A relay production system is used to present the validity of the method and to investigate effects of machining accuracy, measurement accuracy and adjustment accuracy on the maximum production rate and the optimal parameters. The two main results indicate: (1) A range of measurement assembly error and an adjustment size of each reprocessing machine affect the production rate of assembly products within a predetermined assembly tolerance. (2) There exist the optimal range and the optimal adjustment size which maximize the production rate, and they vary according to a combination of machining accuracy, measurement accuracy and reprocessing accuracy in a system.
In recent years, the size of plane substrates and semiconductor wafers has increased. As conventional contact transportation systems composed of, for example, carrier rollers, belt conveyers, and robot hands carry these longer and wider substrates, the increased weight results in increased potential for fracture. A non-contact transportation system is required to solve this problem. We propose a new non-contact transportation system combining acoustic viscous and aerostatic forces to provide damage-free transport. In this system, substrates are supported by aerostatic force and transported by acoustic viscous streaming induced by traveling wave deformation of a disk-type stator. We constructed the experimental equipment using a rotational disk with a 95mm diameter. Electric power was 70W at an input voltage of 200Vpp. A rotational torque of 8.5×10-5 Nm was obtained when clearance between the stator and disk was 120μm. Finally, we constructed a noncontact transport apparatus for polycrystalline silicon wafers (150(W) × 150(L) × 0.3(t)), producing a carrying speed of 59.2 mm/s at a clearance of 0.3mm between the stator and wafer. The carrying force when four stators acted on the wafer was 2×10-3N. Thus, the new noncontact transportation system was demonstrated to be effective.
In recent years, the technology which heightens the output per unit volume by equipping a stator with a high-density coil using divided cores is used widely in order to improve the motor output or the motor efficiency. Since the divided cores really tend to generate work errors compared with the non-divided core, magnetic energy changes by few work errors, and there is a problem that the cogging torque known as torque ripple becomes large. Therefore, in the motor which has divided cores, it is useful industrially to obtain the manufacturing method which reduces cogging torque effectively by simple process. In this research, by using the concentrated magnetomotive force model, the technique of writing the cogging torque resulting from the error of the inside diameter form of a stator as a vector was introduced, and the validity was verified. The rotary lamination method was proposed as a method of reducing cogging torque by making each other offsetting combining two or more torque vectors, and the effect was verified by experiment. In the experiment, the rotary lamination is realized by the manufacturing method with the divided cores which are pierced in the circular shape by a metallic mold. There will be room to study offsetting the torque vector of other factors by control the torque vector arbitrarily using the rotary lamination method of the divided cores.