In recent years, synthesizing diamond film from gas phase is expected to be a new method of surface hardness improvement. Since the diamond film has a rough surface, it may be necessary to be polished. But the adhensive strength between the film and the substrate is too weak to endure the force produced by the conventional polishing method using diamond powders, so some new polishing method is needed. In this study, using the thermo-chemical reaction between diamond and iron, a polishing apparatus is manufactured for trial. A diamond film deposited on a 7 × 7× 4 mm silicon substrate by microwave plasma CVD is used as a workpiece, an iron plate heated to 810°C is used as a polishing plate, the polishing pressure of 60 kPa is much smaller than that of the conventional method, and the polishing experiment is performed in a hydrogen gas atmosphere. After 2 hours' polishing, the diamond surface becomes smooth without any exfoliation.
Reduction projection aligner needs a noncontact measurement means for the position of the wafer surface. A pneumatic gauge is suitable to detect the position of the wafer surface coated with several materials. The pneumatic gauge for this purpose has large outlet diameter which equals the reduction projection area. It must work under large operation gap and at the same time extremely low flow rate for semiconductor process. In this paper, design method and accuracy of the noncontact positioning apparatus with the large-outlet pneumatic gauge and some experimental results are described. Main results obtained are as follows: (1) Positioning accuracy depends mainly on pressure transducer accuracy. (2) Developed apparatus having a 20 mm outlet diameter, and a 90 μm gap, has achieved a positioning acuracy of 0.08 μm (3σ) under low flow rate (0.4l/min).
The die design for cold forging is very important, because the die material is exposed to heavy stress. In order to make precise cold forged products, the die for cold forging must be designed in due consideration of deformation by working pressure. But a lot of cost can not be payed to die design, therefore low cost analysis system for cold forging die has been developed by means of personal computer and BEM. Although personal computer is used, the maximum number of boundary elements is 250, and in usual case CPU time is within 30 minutes. In order to make this system practically useful, a lot of automatic data generation programs and an evaluation program of internal working pressure are added.
A new multiple-input modeling is developed to identify the number and the location of independent vibration sources based on the measured vibration spectrum at several points of the structure during operation, where the vibration sources are guessed to be located. In the modeling the principal power spectrum and the virtual coherence are obtained by he result of eigenvalue decomposition of auto-cross spectrum matrix of measured vibration and used for identification. A simple plate and a complex automobile body which are excited by known forces are used to demonstrate the effectiveness of the proposed method.
This paper describes criteria and generation methods of a curve which has monotonously and smoothly varying curvature under the constraints of tangent directions and curvature values at arbitrary points on the curve. The criteria are represented by the first and second derivatives of curvature and shown as regions of the m-n space whose coordinates are normarized lengths of Bézier edge vectors. The sufficient condition of the criteria is introduced by geometrically determining a control polygon of a Bézier curve with relation to its angles and edge lengths. And these Bézier curves are connected smoothly to satisfy the constraints.
This paper describes a machining simulator based on voxel representation. In order to realize a high level computer controlled machining system, it is necessary to develop the machining simulation technique which is able to forecast machining phenomena such as removal shape and cutting force, cutter collision and so on. Voxel representation is introduced into the machining simulator, which makes it easy to do a logical set operation between objects, and the conversion process from modeling space to voxel space is proposed. Some experimental results of the simulator are also demonstrated.
Vibrations and noises of gears consist of the average component and the fluctuating one. The former is the component which always appears in each tooth meshing. The latter is the component which fluctuates about the average component. In the first report, it was described that the moving average method was very effective for extracting the average component. In that report, a steady rotation of gears was assumed. However, the number of revolution of gears always fluctuates more or less in actual gear equipments. In this report, the generation of the side band waves due to the fluctuation is explained and the allowable value of the fluctuation ratio is given to extract the average component.
An approximate expression for multiple-edge diffraction of sound around a polygonal pillar can be derived based on Pierce's asymptotic solution for sound diffraction around a wedge barrier The effect of multiple-diffracted waves around a rectangular pillar is clarified by calculating the distribution of sound pressure levels for each diffracted wave using the approximate expression. On the basis of the results for each diffracted wave, a practical calculation method of multiple-edge diffraction sound field around a rectangular pillar is proposed. This method is applied to the calculation of the sound field around a rectangular pillar which is produced by a spherical sound wave incident on its side. The calculated results are compared with the experimental ones. In the experiment, a sound visualization technique using three color-light-emitting diodes is used to measure the distribution of sound pressure levels around rectangular pillar models in detail. The calculated results agree well with the visualized ones. All these results show that this calculation method is of practical use.
In the first report, the authors described the mechanical structure of a friction drive system used in this study and the traction characteristics acted between the pinion roller and the slider. Since it became clear by the first report that the traction T had the maximum value Tmax, the acceleration of the slider Vs had also the maximum value Vsmax which was obtained from the dynamic equation in this system. So, when the acceleration of the slider Vs is kept at Vsmax, the trapezoidal velocity control is very effective for the friction drive. The authors discuss the effects of 3 kinds of trapezoidal velocity control ((1) almost without slip between the pinion roller and the slider, (2) with slip and (3) with slip and with integral regulator during deceleration). As a result, it becomes clear that the control of (3) shows the shortest settling time when the slider reaches within 1μm from the desired position.
Thid paper describes a mask-to-wafer alignment technique for submicron X-ray lithography. A new alignment method is proposed to detect lateral displacement in the wide gap range accurately. Wafer grating pitch is twice as large as the mask grating pitch in order to avoid gap fluctuation influence on the lateral displacement detection signal. The dependence of the lateral displacement detection signal on gap fluctuations is disscussed both theoretically and experimentally. A highly sensitive and stable lateral displacement detection signal is obtained at the specific gap. The signal has a triangular wavefrom and hardly varies by gap fluctuations of a few microns from the specific gap. The gap range where the stable signal can be obtained, is fifty times larger than that of the conventional dual grating method. These experimental results agreed well with the theoretical calculation. By combining the double-pitch dual grating method and the single grating method mentioned in the 1st report, accuracies of ±0.02 μm in both the gap and lateral displacement servo-controls are achieved.
An infinite stiffness aerostatic thrust bearing with an active restrictor is proposed. The bearing surface has a central stepped region which functions as a surface restrictor. Because the stepped region is supported elastically by another aerostatic bearing incorporated into the thrust bearing, the depth of the step can vary according to the load applied. Consequently, the applied load is supported without changing the air film thickness on the land of the thrust bearing, and thus the bearing stiffness can be infinite. Therefore, this surface restrictor can be regarded as an Aerostatically-Controlled Restrictor (ACR). The influence of design parameters such as the depth of the stepped region and the stiffness of the stepped-region-supporting bearing is analysed by numerical calculations and experiments. From the experiments, it is shown that while avoiding the occurrence of pneumatic hammer, the thrust stiffness of the bearing with the ACR can be infinite.
A new method for profile measurement using phase-shifting technique is proposed and verified by experiments. The method realizes the measurement by projecting an interferometric fringe pattern as a grating pattern on the object surface and by observing the deformed fringe pattern at the direction different from the projection. The fringe pattern is shifted in four steps by means of a mirror mounted on a piezoelectric translator. Path difference at each point on the object surface is calculated precisely from the four intensity data. From the path difference data, we can calculate the object profile. This technique needs no fine fringe pattern to improve lateral resolving power as it gives height distribution at all the picture elements over the object image. Furthermore, the technique has the advantage that it can measure the object with spatially varying reflectivity. This paper also estimates the measuring errors caused by A/D converter.
We have developed the wide range scanning tunneling microscope (STM) to measure surface topography of a diamond turned gold mirror, a gold coated float polished glass surface and so on. Three dimensional positioning of our STM device is achieved not by using a famous piezoelectric tripod, but by monolithic high precision wide ange translation mechanisms, which we call multi-compound parallel spring. One of strong points of this device is that capability of this specially fabricated X-Y stage is to measure over a sample area of 70μm×70μm and is easily cut from a monolith. We have got an information that each diamond tip trace straightness of the turned surface using a high precision air bearing lathe changes noticeably in the portion. This fact shows that we still have to improve not only such manufacturing conditions as tool radius, and the roughness of tool tips but also the surface finish machine environments especially vibrations.
This paper is related to diamond synthesis from mixed methane and hydrogen gas by microwave plasma CVD. In this study, the effects of substrate surface states on nucleation are experimentally examined. Silicon wafers are finished by different procedures to get different surface states. These procedures are grinding with diamond wheels, polishing with alumina, polishing with diamonds, mechano-chemical polishing with zirconia, blusting with glass bead and etching with mixed acid. In order to estimate nucleation density synthesizing are carried out for 2 hours under the condition of 1% methane concentration. Results obtained are as follows : The nucleation density of crystallographically damaged surfaces is higher than that of non-damaged surfaces. As undulations of the substrate surface affect on the flow of mixed gas, the nucleation density highly depends on the surface roughness.
This research is primarily aimed at the longer tool life of natural single crystal diamond in ultra precision for an electroless nickel phosphorus plating. The following results have been obtained : (1) The profile to increase of the tool life drawn from this work is that back and side rake angle were formed at -5 with nose radius 0.76mm and other tool dimensions has constant values. (2) The groove wear of natural single diamond tool is grown by asperity of tool feed mark on the ultra precision machined surface. (3) The typical tool wear of diamond shows an attrition wear without a chipping failure in the optimum tool profile.
In order to describe quantitatively the grinding process of partially stabilized zirconia (PSZ) with metal bonded diamond wheel, the analytical method established for metal grinding is applied to the grinding process of fine ceramics, and the theoretical values are compared to the experimental values. It is made clear that the plunge grinding process of PSZ with metal bonded diamond wheel can be represented by five independent characteristic parameters such as the size generation acceleration, the wheel wear rate, the grinding system stiffness, the contact stiffness and the cutting stiffness. By the characteristic parameters, variations of the grinding force, the stock removal, the residual stock through a grinding cycle and the grinding cycle time can be predicted.
The behavior of crack initiation, which results in the brittle failure during the cutting, was simulated experimentally by indentation test techniques for cemented carbide cutting tool materials. In indentation test the cracks were observed at a short distance from indenter-specimen contact zone, and at the center of that contact zone. For the former crack path was grain boundary of carbides and interface of carbide particle and cobalt binder, and the latter propagated in carbide particles mainly. Indenting load at which crack occurred decreased with a increase in the number of indenting cycles, and was affected by tool materials and surface preparations. From the comparison of indentation test with transverse rupture test about fracture source and stress distribution, it was considered that in case of stress concentration such as indentation test fracture originated in carbide grain boundaries and carbide particle-binder interfaces, in the other case such as transverse rupture test fracture initiated from a pore or a coarse grain. The appearance of fracture surface and the stress distribution of the brittle failure of cutting tools is similar to those of indentation test, then it is seemed that the crack, which results in brittle failure, occurs at grain boundaries and interfaces, and grows.
A numerically controlled, precision diamond flycutting mechanism has been developed, where tool cutting depth is dynamically controlled in synchronizing to tool rotational angle. This technique permits fabrication of aspheric mirrors used in soft X-ray application equipments, with a contour accuracy of 0.1 μm peak to valley. A piezoelectric stack actuator is used for tool cutting depth control. To correct hystcresis and drift with a piezo-acytuator, a referential piezo-actuator with the same characterisitics as that of the tool is driven in a closed roop control. The signal supplied to the referential piezo-actuator simultaniously drives the tool actuator. Aspherical mirror and a toroidal mirror are cut to evaluate developed flycutting technology.
A cluster of metal bonded diamond wheel (SDC 100) is dressed by GC abrasive sticks of various mesh sizes, and contour maps of the wheel surface topography are drawn by using a three-dimensional profile measuring instrument, which is an improvement on conventional profilometer of stylus type. Characteristic values of topography, i. e., positional distribution of cutting edges in the wheel depthwise direction, tip angle and flat part length of cutting edge, and protrusion height of abrasive from bond matrix are derived from the contour maps. Dressing effects are evaluated by using these characteristics, and following results are obtained : (1) Cutting edges sharpen with an increase in dresser infeed and grain size of abrasive stick. (2) Cutting edge changes the distribution pattern from exponential to uniform when dressing condition becomes rough. (3) Mean protrusion height of diamond grain increases when dress infeed or grain size of abrasive stick becomes large. This tendency to increase is, however, reversed when abrasive stick is excessively coarse and falling out of diamond grain from bond matrix is remarkable.