[in Japanese]

View full abstract

An air bearing lead screw and nut have been developed for application to ultra-precise positioning over long strokes. The design features are : (1) Porous restrictors made of ceramic materials with surface plating are applied to the flanks of the nut threads. (2) The thread profile is square to improve its machining accuracy and this minimizes bearing clearance. Performances of the air bearing lead screw and nut were examined with a fully air-lubricated one-dimensional linear table. Primary results for a lead screw with a nominal diameter of 25mm are : (1) The axial stiffness is over 30N/μm with 0.5 MPa supply pressure. (2) Precision of the nut linear motion is evaluated to be 5 nm. (3) Lead accuracy is improved more than 10 times compared to the machining accuracy of lead screws. These results demonstrate that the air bearing lead screw and nut is a practical approach for micropositioning with ultra-fine accuracy.

View full abstract

A new solid-type end mill is the up-to-date cutting tool made from supertough cermet material, which was developed for end mill. This cermet has TiC and TiN for its main ingredients and equals cemented carbide in elastic modulus and its heat conductivity is lower than one tenth of that of cemented carbide. The tool life of cermet end mill in optimum cutting condition proves to be about two times as long as that of cemented carbide one. This end mill ensures surface roughness of 1μmR_max which is equal with ground surface one. Since cermet end mill is so small as φ2-12mm in tool diameter, restriction from machine tool side at cutting speed and feed rate, also, is considered, but careful consideration is paid to tool design, so that stable cutting could be capable at the cutting speed 30-100m/min.

View full abstract

The Finite Element Method (FEM) is an excellent simulation tool in the Computer Aided Engineering (CAE). It is indispensable to a new product development because of its superiority in wide usability, low computation cost and high accuracy. However, it is difficult to utilize the FEM well enough without experts in the FEM. Therefore, a consulting system for the FEM is required to help beginner to master it by himself. Concretely the following fields in the FEM require a consulting system : (1) modeling, (2) mesh generation, (3) output inspection and a total consulting system for the FEM “FEMHELP” are developed. In this paper, the necessity and outline of the FEMHELP system are shown.

View full abstract

This paper proposes a unified method for generating a corner fillet around a vertex. The method is based on a rolling ball method and a spine of a rolling ball is calculated by a geometrical tracing of intersections of offset surfaces along with the position where the ball contacts three surfaces simultaneously. Generation rules are introduced which can be applied to the corner fillets regardless of a number of edges, radius size and convex or concave. The generated shapes of the corner fillets are natural corresponding to those on a manufacturing shop.

View full abstract

Microcutting of AFRM (Alumina Fiber Reinforced Metal) are performed with SEM direct observation method. The purpose of this study is to make clear the cutting mechanism of AFRM and the fracture of fibers at the plastic deformation zone of the orthogonal microcutting. Since AFRM shows an obvious anisotropic strength depending on the direction of fiber axes, cutting direction are classified by the fiber angle. Summary of the results are shown below. (1) The fracture of fibers in microcutting with carbide tool are caused by shearing, tensile and bending forces. (2) In fiber angle 30° and 60°, the direct collision of fibers with cutting edge of tool were observed with high frequency. In these cases, fibers were fractured by the shearing force. (3) In another fiber angles, fibers were fractured by the bending forces after the severe bending deformation. The amount of deformation in fibers became larger in the case of fiber angle 90° and 120° with an extensive overcut. This enhances difficulties in the exhaust of chip and worsens the surface finish. (4) The deformation zone of the orthogonal microcutting with diamond tool was found to decrease by approximately one-half comparing with carbide tool. This can be attributed to the low friction coefficient between the rake face and a sharp edge of the cutting tool. (5) Four typical cutting mechanism have been proposed by the results of the direct observation of microcutting of AFRM.

View full abstract

This paper presents some experimental results on the mechano-chemical polishing of bulk polycrystal ferrite as well as polycrystal ferrite laminated with other materials. A polishing plate made of tin is used with a polishing fluid chemically active to ferrite such as hydrochloric acid. Using the mechano-chemical process, the stock removal rate can be increased and the damaged layer of the polycrystal ferrite decreased, in contrast with those in the mechanical polishing process. For laminated ferrite, the micro-steps are substantially formed on the polished surface made of different materials. This feature is utilized for finishing the air bearing surfaces of multi-channel magnetic heads, when an electrochemical action is added to mechanical polishing, in order to compose the local cell between a ferrite and either a polishing plate or a laminated material.

View full abstract

Diamond coated cutting tool has been expected to the candidate for a cutting tool for hard materials. In this paper, cutting of hypereutectic Al-24%Si alloy by using diamond coated cutting tools have been examined, and evaluation of the tool has been conducted. Two types of cutting tools are fabricated by depositing diamond films on sintered diamond surfaces, and hot-pressed Si₃N₄ surfaces with microwave plasma chemical vapor deposition method. Cutting of Al-24%Si alloy is done by using these cutting tools. When diamond coated Si₃N₄ cutting tool is used, exfoliation of a diamond film occurs under the small cutting depth of 0.2 mm. On the other hand, when diamond coated sintered diamond cutting tool is used, neither exfoliation nor wear of a diamond film is observed. These results show the latter cutting tool is strong enough to be applied to the cutting tool for Al-24%Si alloy. Furthermore, coating processes of diamond films deposited on Si₃N₄ and sintered diamond are discussed. A diamond film grows epitaxially on diamond crystals at sintered diamond surfaces, whereas a diamond film is formed on amorphous carbon above Si₃N₄ substrate. This shows the reason why the diamond coated sintered diamond cutting tool has much larger resistant ability in comparison with a diamond coated Si₃N₄ cutting tool.

View full abstract

As the wire-EDM is based on discharge phenomena in a dielectric fluid, the eroded surface differs markedly from the base materials in many respects of physico-chemical changc caused by severe thermal actions with an extremely high cooling rate. The analyses about property changes of eroded surface are very important problem in relation to the erosion mechanism and quality of products such as surface integrity, some mechanical properties. The paper mentions the characteristics in degenerated zones due to wire-EDM, using ESCA (Electron Spectroscopy for Chemical Analysis) method which is very effective for analysis on extreme surface of 1-2×10^-3μm depth and chemical combination of elements. As a result, it was proved the existence of Fe oxide (FeO, Fe₂O₃), Cr oxide (Cr₂O₃) and its depth below surface. The density and thickness of wire electrode materials (Cu, Zn) on machined surface were sustained, and it didn't occur oxidization in those materials.

View full abstract

This paper describes the static characteristics and the frequency responses of a new type isolated table which is simple in its structure. The isolated table is composed of four circular arc beams, four oil dampers, a table-board and a base-board. The both ends of the four circular arc beams are fixed on to the four corners of the square table-board and base-board. On the other hand, the both ends of the four oil dampers are pinned at the four corners of the table-board and the center of the base-board. The stiffnesses of the isolated table in the horizontal and vertical directions are analyzed and compared with the experimental results. Its frequency responses in the horizontal direction are measured, and the effect of vibration isolation of the oil damper is discussed experimentally and theoretically. This isolated table has almost the same stiffness in every direction in a horizontal plane, and the directions of the vibration of the table-board and the movement of the base-board are almost the same.

View full abstract

In this paper YAG laser cutting and planing of diamond films synthesized by arc discharge plasma jet CVD have been described. As a result, by controlling the energy density, cutting of a CVD diamond is possible. As for etching of CVD diamond in oxygen gas, preferentially amorphous carbon, grain boundary and fault in grain are vaporized and then diamond grains are oxidized. In the case of cutting, diamonds are removed by oxidization and vaporization in the oxygen gas or by graphitization in the argon gas. Therefore by laser irradiation in the oxygen gas, clear cross sections were gained without graphite deposition. Moreover by controlling the incident angle, the surface planing is possible. The roughness of diamond surface after planing by parallel incident laser beam was 3um Rmax. These diamond films processed by laser could be applied to cutting tools.

View full abstract

As one of the difficult-to-machine materials, austempered bainitic spheroidal graphite cast iron (FCD 1000 A) have been machined so far only by grinding. In the present study, cutting of the FCD 1000 A was tried using CBN tools. Cutting performance of the tools was investigated through determining the optimum combination of condition for cutting and binding phase for the tool materials. For fine cutting of the FCD 1000 A, the optimum cutting temperature was determined as 1 100 K and the best material for the binding phase of CBN tool was TiC from both tool life and surface roughness points of view. From the temperature dependence of flank wear rate, wear behavior of the tool could be classified into two temperature regions, A and B. In the region A, a scratch mark was abundantly observed on the wear surface of the tool due mainly to microspalling of c-BN particles. In the region B, it was significantly observed that the tool wear was controlled by falling-off of adhering particle from the cutting edge.

View full abstract

The study deals with the automatic measuring path generation of 3-dimensional measuring machine (3 D-CMM) with 5 degrees of freedom. The 3 D-CMM consists of the Cartesian coordinate structure and a touch probe with 2 rotational degrees of freedom. The measuring path is automatically generated in off-line on the basis of CAD, taking account of the collision between the touch probe and workpieces. The measuring path is converted to the actual one by matching the CAD data with the image of workpiece being arbitrarily set on the 3 D-CMM. The system enables the measurement without changing the setting of workpieces, which remarkably reduces the measuring time.

View full abstract

This report discusses subjects and countermeasures in order to apply the stripe pattern projection technique to the automatic focusing equipment used in microscopes. The effects of wafer circuit patterns, wafer defocus and illumination system on the detected signal wave of the projected stripe pattern are analyzed. A technique to minimize the detection error of the stripe pattern contrast by eliminating the influence of the circuit pattern on the stripe pattern image is described. Also, an illumination technique to secure a uniform stripe pattern image and a detection technique to improve contrast detection accuracy are discussed. Using these techniques, a repeatability of ± 0.6μm (3σ) and an accuracy of ±1.0μm (3σ) in automatic focusing have been achieved.

View full abstract

The calculation formula for zooming FFT, by which zoom FFT analysis can be carried out on a personal computer without any special FFT instruments, was derived by applying the same procedure that the Fast Fourier Transform was derived from discrete Fourier transform. According to the derived formula, a BASIC program of zoom FFT was coded, and was applied for analyzing the gear transmission errors measured on two tested gear pairs. By selecting a zoom ratio equal to the lowest common multiple of their gear- and pinion-tooth number devided by the gear tooth number, their gear- and pinion-low harmonics were distinctly separated and extracted without piket fence effect. And the amplitudes of the pinion low harmonics corresponded well with the hearing noise levels of the tested gear pairs.

View full abstract

An approach was given to estimating straightnesserror curve using identification technique and Kalman filter in a previous short paper. This approach can compensate accidental errors which are mixed to the measuring values from displacement sensors when a serial three point method is used. In this paper, the following facts are revealed by simulation and some experiments. (a) This approach is a match in measuring accuracy for a serial multi-point method which uses four displacement sensors. (b) This approach is superior in accuracy and repeatability to a serial three point method. (c) This approach shortens the computer processing time to 1/10 comparing with a serial multi-point method.

View full abstract

This paper deals with a failure diagnosis of a pneumatic directional control valve used in automated production systems. The valve vibration is monitored by an accelerometer : Six parameters characterizing the vibration data are extracted, and fed into multi-layer neural networks to solve four types of diagnosis problems. It is shown that the neural network approach is useful for the failure diagnosis, yielding low failed-safe and low failed-dangerous probabilities. Neural network structures are analyzed through Boolean expressions summarizing relationships between two successive neuron layers. These expressions are obtained by noting that, for learning patterns, occurrences of discrete failure events behind continuous network input parameters are known. For each neuron, its function can be clarified by the structure analysis; irrelevant neurons can be identified and removed without degrading the diagnosis performance; the neural network for a diagnosis of foreign material around a spool utilizes a majority voting mechanism, and attains a 50% reduction of incorrect answers compared with a linear diagnosis. A conjugate gradient followed by a variable metric method is demonstrated as an effective learning algorithm.

View full abstract

High-speed and heavy-duty grinding of non-circular workpieces generally requires high rigidity of the overall mechanical system including the wheel feed system and the workpiece rotating system. Conventionally, hydraulic systems, such as the hydraulic copying mechanism and hydraulic servo mechanism, with which high power can be obtained relatively easily were mainly adopted as the drive system for highly rigid machine tools. However, electrical servo mechanisms capable of outputting high power are gradually being adopted by NC system. This paper discusses two problems; (1) improving in profile interpolation accuracy and (2) improving in servo error in high-speed grinding. Both problems are related to control technology and both will arise when an electrical servo mechanism is adopted for high-speed high-accuracy non-circular profile grinding. Solutions are offered for both problems. The solutions proposed by this paper are high speed, automatic generation of minimum linear interpolation data, the feed-forward control method, and the profile error compensation method. Prototype test equipment has been made to evaluate the feasibility of the solutions and to check how they can be adopted.

View full abstract

The three-point methods such as the summit method and the rider method give convenient way of assessing circularity. Especially, the method by the use of three displacement detectors is a promising technique to separate precisely the circularity profile of a workpiece from apparent runout on a machine tool. Several in-situ circularity measuring systems based on this method have been developed so far. In these systems, however, relative angles between three detectors are not necessarily determined in a reasonable way. In this study, the performance index of the detecting angles has been derived by applying the law of error propagation to the method and the most reasonable angles have been determined by optimizing the performance index. In addition, by utilizing the performance index, generalized n-point method has been developed and its effectiveness in improvement of measuring accuracy has been verified analytically and experimentally.

View full abstract

There are many types of defects in wood, some of which reduce strength of structure parts or spoil the appearance of furniture parts. To make efficient use of valuable wood free from such defects, it is desired to develop an automated inspection system which is able to locate the position and extent of each defect present and to identify the type of defect at each location. In this paper, we propose an automatic inspection method to detect and discriminate surface defects in wood. The essential points of the method are as follows : Input gray level image of testing wood is divided into a number of regions and several tonal property measures are extracted from image of each region, and fuzzy clustering technique is adopted for detection and discrimination of surface defects. Applying the proposed method to inspection tests of actual lumbers, we obtained the following results : (1) Defect detection can be achieved almost completely. (2) Discrimination rate ranges from 25 to 82% depending on the type of defect, and this indicates that more research is needed.

View full abstract

A new type of hologram interferometer for null-testing and measuring a paraboloidal mirror configuration is proposed. In the interferometer a hologram causes a spherical reference wavefront which interferes with a spherical wavefront reflected by a paraboloidal mirror under test. The method to calculate the amount of configuration error of a paraboloidal mirror from the interferogram is also proposed. Almost straight and equally spaced tilt fringes obtained in the experiment for a commercial on-axis paraboloidal mirror shows the interferometer is useful.

View full abstract