In order to improve machining accuracy of diamond turning, an acoustic emission (AE) feedback control scheme is considered in this paper. An acoustic emission root means square (AErms) signal is utilized to integrate additional AE feedback control loop with a conventional position feedback control system. In preliminary experiments in advance of the AE feedback control design, a correlation between a machining error and a measured AErms has been verified. Based on the preliminary experiments, the AE feedback control system has been designed. The designed controller calculates a compensation signal for the conventional position feedback system to improve the machining accuracy. Machining tests using a diamond turning machine showed that the proposed controller accomplishes 20 percent reduction of machining error compared to conventional position feedback control. Machining tests using various diamond cutting tools showed that the AE feedback can be applied for on-line tool wear monitoring.

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It is difficult to machine a comparatively wide but very thin three-dimensional parts, because it is easily deformed by the clamping force or machining force during the machining. In this paper, a simple method using low melting alloy (LMA), whose melting point is below 100°C, to support the thin parts is proposed. The parts are firmly supported and fixed on the LMA by adhesion or suction force. The LMA and the adhesive are removed after the machining by hot water. This method is suitable for machining a few three-dimensional thin parts, or prototype parts for preliminary assessment before mass production. The parts of minimum thickness 20μm was obtained. The method and investigated results are described.

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Supplying pressure effects of grinding fluids on grinding commercial purity titanium (CP titanium) have been studied to establish the optimum condition for ultra precision grinding for mirror-like finishing. Roughness, flatness, normal grinding forces and residual stresses were examined on work surfaces relating to the type of grinding wheels and the kind and supplying pressure of grinding fluid. The resin-bonded diamond wheel #1200 is recommended for grinding CP titanium, and it was found that the high-pressure grinding fluid supply was an effective way to obtain mirror-like surface. By choosing a chemical solution as grinding fluids and at the supplying pressure of 7 MPa through the nozzle located 5 mm away from work, the accuracy of work surface has reached Ry = 0.1 μm in surface roughness and 1.0 μm in flatness. The results obtained were discussed from the viewpoints of the cooling effects of grinding fluid supply on grinding accuracy.

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This study describes a new method to achieve the high precision end-milling on a 5-axis controlled machining center. We attracted attention to multi-blade end-mill tools with high helix angle in order to keep a constant cutting force in side milling. It is well known that the convex and concave error on the machined sidewall surface is generated due to the variation of cutting force in end-milling using the multi-blade end-mill tools. On the other hand, the constant cutting force is obtained in end-milling adequate thickness workpiece using the multi-blade end-mill tools with high helix angle. The constant cutting force makes it possible to decrease the machined surface error due to the variation of cutting force. Therefore, we propose a method of tilting the workpiece by controlling A or B axis in order to obtain a proper cutting thickness of sidewall.

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In recent years, the frequency conversion technique using nonlinear optical crystals are becoming more and more important for the applications of solid-state lasers to precision microfabrication. For the first step of the study, we have analyzed the temperature dependence of SHG conversion efficiency theoretically, supposing uniform beam. The complex wave amplitude equations were derived, considering the absorption of laser in the crystal. The results were presented in the previous paper. In this paper, the analysis was carried out two-dimensionally with an axisymmetrical model based on the previous one-dimensional model, applying the paraxial approximation. Two-dimensional temperature distribution induced by laser absorption and variation of the conversion efficiency of KDP crystal were analyzed quantitatively during repetition irradiation of pulse laser. The influences of pulse width and beam intensity distribution were also investigated Main results are summarized as follows: (1) Depending on SHG and its inverse conversion, temperature of the crystal with Gaussian beam irradiation fluctuates remarkably in the axial direction. (2) During Gaussian beam irradiation, heat conduction in the radial direction prevents temperature from rising in the central part of crystal. (3) The conversion efficiency for a Gaussian beam stays relatively high for a long period, compared with that of uniform beam.

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Cutting edge of a sphere portion (end cutting edge) of the ball end mills is treated as the intersection of a spherical surface and a rake face approximated by a plane surface. The cutting edge configuration is geometrically analyzed, and variation of inclination angle and normal rake angle along the cutting edge is discussed. In addition, it is assumed that the line elements along the curved cutting edge of the sphere portion do not undergo extension or contraction, and the modified condition of side-curl of the chip is introduced. Then a cutting model and energy method developed for the drilling process is extended to the milling process. Expressions such as area of the shear plane and projected area of the cutting cross-section on the rake face are derived for slot milling. From the analytical results obtained through energy method, it is found that the center of side-curl of the chip is fixed near the top of the sphere portion of ball end mills and the chip is produced under this restricted condition. Furthermore, predicted result shows that Stabler's chip flow rule does not hold for the milling with ball end mills.

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In the previous report, we have found that the TiCN PVD-coated carbide tool is useful for ultra-precision cutting of titanium metal. This report aims to clear the effect of cutting fluid on surface roughness formed by ultra-precision cutting of titanium metal with the coated carbide tool. Cutting fluids used are kerosene for general ultra-precision cutting of soft metals, and three kinds of water-immiscible cutting fluids, which consist of fats and oils, fats and oils with special additives, fats and oils with extreme additives of sulfur type, respectively. The surface roughness formed using the water-immiscible cutting fluids is better than kerosene. The additives contained in the water-immiscible cutting fluid have the great influence on the surface roughness. The mist fluid supply method in which the fluid is supplied together with compressed air to the cutting point, is superior in getting the smooth surface roughness to the spray fluid supply method. The finished best surface roughness obtained using the best water-immiscible cutting fluid, which consists of fats and oils with special additives is about 60nm(P-V) for α-β titanium alloy.

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The objective of this study is to clarify the optimum direction of tool revolving axis where the machining error of the surface geometrically becomes the minimum in 5-axis machining. This paper describes the dependence which is derived from geometric data of machined surface and position of cutting edge. The shape of machined surface is defined by the trajectory of spiral cutting edge, and calculated with 785 orientations. The dependence is analysed from the following view points: (1) Optimizing direction of tool revolving axis, (2) Classification of boudaries of unit machined region, (3) Optimizing twisted angle of spiral cutting edge. As useful results of this report, (1) both the best and the worst orientation were found at very small tilting angles. In the worst case, the trajectory of cutting edge generates the complicated surface, because of the stationary point of velocity along feed direction which locates inside of the machined region rather than outside in the best case. (2) Symmetric boundaries were observed at symmetric axis direction. Boundary of the worst case was complicated, too. (3) Effect of twisted angle is shown periodically.

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With the purpose of developing the high efficient electrolytic dressing method for bronze bond diamond wheel of a coarse grain, twin electrode electrolytic dressing method using DC power source is devised and the validity of its method is examined by the experiments. In the larger initial electrolytic current value than the critical value, the electrolytic current value decreases with dressing time until a constant corresponding with dressing conditions because the oxide layer generated by the electrolytic reaction increases with dressing time. In the suitable initial electrolytic current value below the critical value, on the other hand, the electrolytic current value is independent on dressing time because the oxide layer does not increase with dressing time. In the suitable dressing conditions, the grain extrusion height from the bond surface increases efficiently in approximately proportion to dressing time beyond the height of 35μm which is about one-third of abrasive grain diameter of #140 wheel. The grinding performance of wheel dressed suitably by twin electrode method has longer dressing life interval, smaller variation of surface roughness in grinding process and larger grinding ratio than single electrode method. From the results, it is referred that the method is useful for dressing of coarse grain wheel of #140.

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This paper describes a computer generated hologram (CGH) on a curved surface for laser machining. The CGH fabricated on a parabolic copper mirror converts a 14mm diameter Gaussian beam of a CO ₂ laser into a shaped beam whose intensity distribution is uniform (4mm) in x direction and gaussian (1mm) in y direction. The binary CGH pattern was drawn by a laser direct writing machine with a focus servo mechanism. To obtain an accurate step height of CGH pattern, a palladium thin film was placed between the copper mirror and a plated copper layer 3.75μm thick. While the plated layer was etched by a ferric chloride solution, the palladium film prevented the substrate mirror from being etched. The beam shaping by the fabricated CGH was demonstrated experimentally with a low power CO ₂ laser and an infrared-camera.

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High speed feed drives are being introduced to machining centers for aiming high speed and high productive machining. High lead ballscrew drives are generally used in practical applications, as they are cost-effective and robust to disturbances such as cutting forces. However, ballscrew drives suffer from vibration due to low damping of ball or roller guideways which are commonly used in high speed feed drives. This paper deals with a dual actuation drive, which has direct actuators in the drive table as well as conventional ballscrew drive mechanism. In this actuation system, relative velocity feedback (RVFB) controllers are investigated to give the adequate damping for servo system. By using modal analysis, RVFB gain can be interpreted as damping ratio of 2 mass vibration system. Three types of RVFB are analyzed and compared to direct velocity feedback (DVFB) theoretically. The damping control performance is examined by numerical simulations and experiments, which have good agreement with the theoretical analysis.

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This paper discusses an apparatus for optically detecting dimension or displacement. In particular, the optical unit with compact in size and simpler in construction, and signal processing unit with resolution to be better than 0.1μm are described. The key device of the optical unit is linear scale. The scale consists of one moving and two stationary gratings, and these two types of grating have different grating pitch lengths. These two pitches are set to odd integer multiples. For example, moving and stationary. gratings set to 50μm and 10μm, respectively. The scale is directly irradiated by a divergent light emitted from a laser diode, and generates two sinusoidal-like signals with 10μm period. By using the divergent light, the need for a collimating lens is eliminated. This reduces the overall size of the optical unit The signal processing unit operates on the two signals for, detecting the signal phase at the stop position of the moving grating. The basis of the phase detection is a linear operation. By using the linear operation system, high resolution detection of the signal phase is accomplished by segmenting the one cycle period into more than 300 parts.

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This paper presents a surface motor-driven multi-axis stage system employing a surface encoder as the position feedback sensor. The surface motor consists of four two-phase linear motors, two pairs in X- and Y-directions. The thrust force generated by each of the linear motor's two phases was investigated for the purpose of constructing dynamic controller of the stage. It was confirmed that the thrust forces of the two phases were sinusoidal functions of positions with a shift in space by one-quarter of the motor pitch length of 5 mm. A simple commutation law was applied to the two-phase forces so that a constant force can be obtained throughout the full range of travel. A PC-based PID controller was designed and constructed for micro-positioning experiments of the stage. Experimental results indicated that dynamic micro-positioning can be carried out independently in X and Y-axes with a positioning resolution of 50 nm.

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The present paper introduces an electrostatic microactuator called the conical spring linear actuator (CSLA) which is capable of stepwise motion vertical to the substrate. The CSLA has a moving electrode, in the form of a three-dimensional conical spring, which is placed on four base electrodes. In order to realize the conical spring shape, the moving electrode is constructed of thin film metallic glass (TFMG), which is a new MEMS material. TFMG is a kind of amorphous alloy which softens at a range of temperatures referred to as the supercooled liquid region (SCLR). In the SCLR TFMG can easily be deformed into 3D structures. The present paper introduces a new fabrication process which can be applied to the integration of the CSLA and discusses experimental driving of integrated CSLA. The integrated CSLA shows 200 μm total stepwise displacement vertical to the substrate.

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A flexible electrostatic linear actuator has been developed. The actuator consists of a pair of a stator film and a slider film. Films are fabricated using flexible printed circuit technology. Size of the film is 29mm x80mm x 200μm and weight is 0.7g. Since this actuator consists of flexible films only, it can be bent easily. In this study, thrust force of the actuator, when it is bent, is analyzed theoretically. The theoretical analysis indicates that the actuator can work with sufficiently large force even if it is bent π rad. The theory is verified by experiment. Furthermore, two kinds of multi-layered structure are proposed for high power applications.

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An evaluating map of rubber roller for flexible media handling system, which can describe an operating condition of each rubber roller for well handling of flexible media, is introduced using two design parameters for the handling system such as speed of driven flexible media and applied load between rubber roller and drive media.
Potential and durability of rubber roller for flexible media handling system can be evaluated by the range of operating condition for well handling of the paper in the map. The usefulness of the map is proven with the experimental results observed in handling system with rubber roller and paper.

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