Liquid crystal displays are commonly used recently, but productivity is not so satisfactorily high enough due to the occurrence of the uneven display of brightness. Based on our empirical study, these uneven display are believed to be caused by one of the most important processes, called rubbing process for liquid crystal display production. Since it was reported that frictional energy and rubbed area density are correlated closely with anchoring strength of liquid crystals, it was believed that fluctuation of frictional energy is the main reason for the occurrence of uneven display of brightness. In this research it was elucidated that the correlation between fluctuation of frictional energy and uneven display of brightness and proposed rubbing condition to prevent the occurrence of the uneven display of brightness.

View full abstract

As a conventional method, a numerical control inputs a large amount of NC data from CAM system, and interpolates it in order to machine sculptured surfaces. Recently, NCs with the function of NURBS interpolation have been developed. It seems that some problems are resolved using the technology. However, it is said that both methods have some essential problems, so it is hard for NC to transact these problems to machine sculptured surfaces with high quality. This paper discusses these problems from the viewpoint of relation between CAM and NC. Then, a numerical control with the function of surface driven interpolation is proposed as an ideal system. The conceptual idea, the implementation method and the prototype are introduced. Then, it is shown that the evolution to NC with surface driven interpolation will come true after NURBS-NC.

View full abstract

A method of threshold setting has been developed based on a multiple regression analysis in an automated visual inspection. The threshold is assumed to be a linear combination of the local difference, local brightness, local contrast, etc. of the two gray-scale images to be compared. The coefficients of the linear combination are determined by the multiple regression analysis using a scattered diagram of the two gray-scale images. By this method good performance can be realized to justify the threshold setting according to the patterns to be inspected even when the inspected patterns are changed. This method is confirmed to be useful for a comparison inspection of complicated LSI multi-layer wafer patterns as a result of some experiments.

View full abstract

Fatigue test of single-crystal-silicon thin films under uniaxial tensile condition was performed on a silicon chip. In this on-chip tensile testing method, tensile testing specimen integrated with loading mechanisms on a same silicon chip was used for the characterization of mechanical property.A newly introduced testing machine allowed experiments under both quasi-static and dynamic loading conditions. An external loading actuator pushing the testing chip precisely traveled in horizontal direction owing to air bearing support and linear DC servomotor. The displacement of the actuator was detected with a sensor having a resolution of 0.1 μm, and applied load was measured by a load cell with a resolution of 1 mN. Measurement accuracy was proved by performing quasi-static tensile test of single-crystal-silicon whose tensile axis was oriented in a <100> direction. Sinusoidal cyclic load was applied to the testing chip with the maximum strain of 3.9% and the frequency of 10 Hz. Fatigue failure was observed as a decrease in the detected force, while the applied displacement didn't change.

View full abstract

Following the first phase of system design and development, this paper places the emphasis on the process development and enhancement for the automated honeycomb repair system. In this report, an active force control has been developed for the chiseling process and the optimal parameters have been established for the belt polishing process. The active force control was originally developed to avoid the overload problem on the robot arm, and consequently extended the robot running at its full capacity. The parameter for polishing process was optimized using "Taguchi method". As the result, the productivity was improved about 30%-50% and tool life was doubled.

View full abstract

Molds and dies with complex shapes are usually fabricated using numerically controlled (NC) 3-axis milling machines with a spherical cutter. Most CAM systems compute the cutter path based on the geometric model of designed surfaces. hi order to avoid gouging problems in the milling process, a tool reference surface representing the offset shape of the designed surface is computed prior to the path generation. This surface corresponds to the upper portion of the swept volume of the inverse cutter moving around the surface. In this paper, the authors propose an acceleration method of this inverse offset computation using the hidden-surface elimination mechanism of the 3-dimensional graphics acceleration hardware. Computation time of the proposed method is basically proportional to the total number of polygons approximating component surfaces of the swept volume. Some portions of the component surfaces do not contribute the result shape of the tool reference surface. Our algorithm reduces the number of polygons (and computation time) by properly excluding such surface portions from the tessellation. An experimental program is implemented and some tool reference surfaces for milling complex mold shapes are computed.

View full abstract

In this study, the wettability of liquid metals on clean solid surface is investigated by ab initio molecular orbital calculations. The two-atom and the cluster-adatom model calculations are performed in order to yield a fundamental interpretation of wetting. Molecular orbitals and total energy in the most stable state are obtained by the restricted open-shell Hartree-Fock (ROHF) method. Calculated binding energies are qualitatively in good agreement with the interaction energies estimated from measured contact angles. Consequently, it is found that wettability is fundamentally determined by the binding energy between the atoms of liquid metal and substrate surfaces.

View full abstract

This investigation deals with the rate of heat transferred to the workpiece and the heat removed from the workpiece in cool air grinding with a porous metal bonded diamond wheel (PMBDW). The following conclusions are obtained from the grinding tests: Blowing cool air onto the workpiece causes its temperature to decrease before grinding, leading to a low grinding surface temperature. Heat is removed from the grinding zone with the presence of cool air, so that the rate of heat transfer to the workpiece decreases. The amount of heat removed by cool air increases with the increase in the wheel pore rate, the increase of the wheel speed and the decrease of the table speed.

View full abstract

Coating effects of organic polarity substance, such as carboxylic acid, on the chip formation mechanism of orthogonal cutting have been investigated both for annealed irons and for work-hardened irons. Coating materials are non-polarity liquid paraffin, liquid paraffin containing 0.2mass% oleic acid and pure oleic acid. Cutting speed is 1.67mm/s and cutting depth is 0.02mm. The following results are obtained. 1) For work-hardened irons, 0.2mass% and pure oleic acid are effective for the decrease of cutting force, the improvement of cutting surface roughness, the thinning of chips and the decrease of lamella thickness in shear-type chips. 2) The above-mentioned phenomena are unable to be observed in annealed irons where chips are tear-type. 3) From the infrared spectrum measurement, the chemisorption between oleic acid molecules and Fe atoms is estimated at the area of high dislocation density such as upheaved region in front of cutting chip.

View full abstract

High speed, High productive tapping has been studied by using newly developed intelligent machine tools. The intelligent machine tools have three levels of feedback loop, which can control the cutting force during tapping process and can decide the cutting condition with conventional feedback loops of position, velocity and current of spindle motor and servo motor. Cutting force, torque and thrust force, which are calculated by internal sensor coincide with measured force of dynamometer during tapping process. It is possible to monitor cutting force of M4 tap and larger for steel, cast iron and aluminum alloy. In continuous cutting of tapping, increase of cutting force is detected by internal sensor. Increase of cutting force is occur to tool wear, so tool life is estimated by this increase of cutting force. And the internal sensor can monitor chip jamming during tapping process. Generally the adaptive control is changing of cutting condition. For tapping, it is not enough to avoid troubles that control cutting condition as compared with the other machining modes, such as drilling, end-milling, face-milling. So an adaptive control is developed which is also change the servo parameters. Using this adaptive control, the productivity of tapping process is greatly improved and is achieved safely.

View full abstract

Turning tests, using two kinds of single crystal diamond tools, were conducted to provide the possibility of ductile regime turning of glass-like carbon material, suitable for precision parts. In the case of a truncated shape tool, which has little contact area with workpiece, ductile regime turning is possible. As the feed rate decreases, a transition mode, where the planar surface-layer area is removed, appears instead of ductile regime material removal. In the case of R shaped tool, which has large contact area, ductile regime turning is hard to recognize because the machined surface directly changes from elastic to brittle fracture as the depth of cut increase. The brittle fracture starting depth of the R shaped tool is around 1 μm, and the brittle fracture starts at 0.5 μm depth of cut as the feed rate decreases.

View full abstract

The study deals with manufacturing curved holes such as water channels of mould and die, which are difficult to create. As holes are generally formed by drilling operations, curved holes are approximately formed as the combination of straight holes, which leads to the interference with smooth stream of coolant. To solve the problem, a quite simple mechanism to create a curved hole was devised, which consisted of a helical compression spring, wires, pulleys and an electrode for electrical discharge machining (EDM), and was installed on an electrical discharge machine. The mechanism allowed the electrode to move along a curved line. However, the length of machinable curved hole was not necessarily sufficient. Therefore, the structure of the device was improved so that the electrode can move longer than the prototype along the curved line. From experimental results, it is found that the improved mechanism enables a longer curved hole machining. In addition, L-shaped curved hole could be obtained by connecting two curved holes machined from two perpendicular directions.

View full abstract

A velocity spectrometer for a neutral atomic beam has been developed to create a mono-velocity neutral atomic beam. In order to disperse a neutral atomic beam depending on its velocity, a magnetic circuit with a large and uniform magnetic gradient has been developed for the first time. The magnetic circuit was made up of quadrupole field configuration of NdFeB permanent magnets. The magnetic gradient in the circuit was measured to be sufficiently large (1T/cm) and uniform. It is possible to use the magnetic circuit as a focusing lens as well as a prism of the spectrometer for a neutral atomic beam. The resonant fluorescence spectra of the Li atomic beam that passed through the magnetic circuit were measured by using a single mode tunable laser. From the peak shift of the fluorescence spectrum, the exerted force on Li atoms by the magnetic gradient in the circuit was 10000 times as large as the earth's gravity. It is expected that a mono-velocity Li atomic beam of 1000m/s with 1% resolution can be created with a compact experimental arrangement using the developed velocity spectrometer.

View full abstract

This paper describes a revolutionary new deposition process by using micro electrical discharge machining (micro EDM) to fabricate highly complex 3-dimensional microstructures without special material or machining fluid. Steel or aluminum alloy is used for both the tool electrode (diameter 0.1mm) and the workpiece, and the EDM process is carried out in air or nitrogen gas. The suitable discharge conditions for this EDM deposition process are predicted from the transient temperature analysis of the tool electrode and the workpiece. In this analysis the energy distributions in the tool electrode and the workpiece which depend on the material combination of the electrode and workpiece and polarity are considered. The experimental results show that micro rod 0.14mm in diameter and 2.2mm in height is formed on the workpiece surface when the polarity of the tool electrode is positive. The deposition process is realized whether the tool electrode material is the same as that of the workpiece or not. It is also found that the deposition process can easily be switched to the removal process by changing only the polarity of the tool electrode.

View full abstract

Multi-wire sawing is one of the most effective slicing methods for large, hard and brittle materials such as silicon ingots. In order to achieve high efficiency slicing of hard and brittle materials, a new slicing method (work rotating type multi-wire sawing) is devised. When using work rotation type multi-wire saw, the wire maintains intermittent contact with workpiece during the process, thereby making it easy for slicing debris to escape from the slicing regions. The main purpose of this study is to make clear the slicing performance of a newly developed work rotating type multi-wire saw. Work material used in the study is borosilicate glass, which is cylindrical. The main results obtained are as follows: (1) The work rotating type multi-wire saw makes it possible to achieve high efficiency in slicing of hard and brittle materials. (2) Work rotating type multi-wire saw is very effective in removing the slicing debris and improving the surface roughness of the sliced surface. (3) High efficiency slicing is achieved when rotational direction of work and running direction of wire are the same. (4) The wire tension should be as large as possible.

View full abstract

In this research, a transportation phenomenon of the mediator and the reaction mechanism of etching on the electrochemical etching by using mediator are clarified. Driving force for the transportation of the mediator is under the control of concentration gradient according to the diffusion. Because the electric potential in a location over 10nm from an electrode is small that it may be disregarded and the current density is proportional to an inverse number of the square root of a time. An etching shape is decided by the location with the constant equilibrium oxidizer. This conclusion was derived by the following experimental results. The current in etching process is decreasing with time and gradually approaching the equilibrium value. As the distance from an electrode to a specimen becomes smaller, the diameter of an etching region becomes larger. A cylindrical etched shape is gotten in etching process by using a cylindrical shaped electrode.

View full abstract

Nanoperiod multilayered films were deposited by controlling the time the substrate was positioned opposite each of the graphite and boron nitride semicircular targets. The wear depth of the 4-nm-period multilayered film is the lowest of all the sliding cycles; therefore, the wear resistance is clearly improved for a 4-nm-period layered film. To clarify the reason why the wear resistance of these multilayered films increases, the wear properties of the load conditions under which the wear increases atomically were evaluated by varying the number of sliding cycles. The wear depth increases with increasing the number of sliding cycles. The weardepth increase rate of the 2-, 4- and 8-nm-period layered films is almost zero at a 1, 2, and 4 nm wear depths, respectively. This wear depth corresponds to the thickness of the interface of each carbon nitride [C-N] and boron nitride [B-N] layer. At both edges of the wear scar, short steps of layered depth were observed in the half-thickness of each period-layered film. These results indicate that the wear resistance increased because of the prevention of fracture growth at the interface between B-N and C-N layers in the case of multilayered films. To realize single-layer processing, the processing properties dependencies of the load and sliding cycles were evaluated. Under suitable conditions, the processed depth corresponds to the depth of each C-N and B-N layer. As a practical application of this newly developed fabrication technique, three-dimensional nanometer-scale profiles, such as 300 nm × 300 nm square, lines and spaces with 100 nm periods and three-step grooves were fabricated.

View full abstract

In the ball-end milling, the surface roughness along the feed direction must be considered when feed per tool revolution was increased. However, if the surface pattern can be controlled, it is possible to use the pattern for industrial design and to reduce the hand-finishing process of molds. In this research work, the generation mechanism of the surface pattern on a curved surface is analyzed theoretically and experimentally. In the experiment, the angular position of the cutting edge of the ball-end mill is controlled according to the proposed algorithm in which the traverse time along the tool path is precisely calculated. From the experimental and theoretical results, the feed speed received the effect between number of blocks and distance between blocks. It is found that the surface pattern on cylindrical and spherical surfaces can be controlled by the proposed method considering actual feed speeds.

View full abstract

The paper presents a structure model with single degree of freedom which may represent the non-linear characteristics of actual machine tool structure. By using an experimental set-up for orthogonal turning which utilizes the proposed structure model, it is shown that the non-linear variations of vibration parameters m, k, c with applied load can be measured with a special impulsive excitation technigic during the actual turning. Th obtained variations are proved to be quite similar to those obtained for usual turning lathe. Computer simulations of chatter on-set process are then carried out with taking both the variable m, k, c obtained and the non-linearity of cutting process reported in the previous papers into account. The predicted stability thresholds of chatter vibration through the simulation are in good quantitative agreement with the experimental results which include the well-known non-linear phenomena such as high feed and high speed stabilities of chatter and the finite amplitude chatter vibration.

View full abstract

Motion errors of an ultraprecision hydrostatic feed table are analyzed in the present research by developing a new model utilizing a transfer function. Relationship between film reaction force in a single hydrostatic pad and form errors of a guide rail is derived at various spacial frequencies by FEM analysis, and it is expressed as a transfer function. This transfer function clarifies so called averaging effect of the oil film quantitatively. For example, it is found that the amplitude of the film reaction force is reduced as the spacial frequency increases or relative width of the pocket is decreased. Furthermore, the transfer function is utilized to estimate motion errors of a multiple pad table from form errors of a guide rail, and also to estimate form errors from motion errors. A new method is proposed by which the motion accuracy of the table is improved by lapping the rail surface so as to eliminate the estimated form errors, and its validity is verified analytically in the present research.

View full abstract