Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.11420/jsat.62.33

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer International Publishing  

This paper reports an improvement of the particle-excitation flow control valve. The valve that we have designed in previous reports can control air flow, using particle excitation by piezoelectric resonance, and has the following advantages: small size, lightweight, high response and continuous airflow control. However, in our previous models, the relationship between the driving voltage and the flow quantity was nonlinear. In this report, we improved the valve to realize proportional flow control. The valve consists of the orifice plate, that has some orifices, and steel particles to seal the orifices and piezoelectric transducer. It controls air flow by the voltage applied to the transducer. For proportional flow control, it is important to adjust the orifice position adequately. In this report, we optimized the orifice position, considering resonance condition of the valve. We designed the experimental prototype using a bolt-clamped Langevin type transducer and decided orifice position. And we evaluated its vibration properties and flow-rate characteristics. The experimental results showed that our designed prototype can proportionally control airflow.

DOI： 10.1186/s40648-017-0093-3

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

<p>Diamond cutting tools shows severe wear in turning of steels. In previous paper, it was shown that carbides on ferrite phase, which were precipitated by carburization, suppressed the diamond tool wear. In this paper, detailed distribution of constituents of the carbides was analyzed by EDS (energy-dispersive X-ray spectroscopy). In addition, characteristics of each carbide such as occupancy, diameter, and degree of circularity were measured. Results indicate that those characteristics of the carbides influence suppression of the tool wear.</p>

DOI： 10.1299/transjsme.17-00161

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

This study aims to verify whether the three-dimensional internal information acquisition system we have developed can be applied successfully to the microstructures of consecutively precision-machined biological samples, and to those of metallic samples. Therefore, this study mainly deals with biological hard tissue samples like bones. In this paper, we first studied the precision-machining characteristics of bones. From this, we determined that, to obtain machined surfaces sufficient for internal observations, we need to determine the maximum uncut chip thickness and the cutting speeds, taking the bone’s anisotropy into consideration. Next, we acquired three-dimensional internal information on consecutively precision-machined bone samples using the three-dimensional internal acquisition system we developed. Subsequently, we visualized the internal structures of these machined samples. Our tiling observations acquired an 18 × 9 × 3 mm segment as a 6.2 × 6.2 × 10 μm resolution image. We obtained a three-dimensionally reconstructed image of complex blood vessel networks inside the bone by making the acquired images binary.

DOI： 10.20965/ijat.2017.p0883

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

Recently, demands have increased on fabricating complex and accurate structures by ultra-precision cutting. However, the machinability is influenced by crystallographic orientations in micron/submicron cutting. In our past work, it was clear that the crystal anisotropy affected the elastic recovery in submicron groove cutting of single crystal copper. Before the experiments, three-step cutting, i.e., rough cutting, intermediate cutting, and finish cutting, have been employed to flattening single crystal copper surface. The depth of affected layer was thinned by increasing the number of intermediate and finish cutting. Nevertheless, few microns of affected layer remained on finished surface. The rough cutting step is considered to cause the remaining affected layer. In this paper, we have investigated the effect of cutting conditions of the rough cutting step to reduce the depth of affected layer. The Schmidt factor of each slip system was calculated from measured cutting forces. Results suggest that the slip system and its Schmidt factor may explain the machinability, and results indicate that the thickness of affected layer decrease with an increase in cutting speed.

DOI： 10.2493/jjspe.83.967

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Publishing type：Research paper (scientific journal)  

DOI： 10.2493/jjspe.83.762

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

In planarization processes of sapphire, lapping process takes a long time because sapphire is a hard material. In contrast, superfinishing, which involves fixed abrasive machining, can substitute for lapping, and it would be possible to shorten the amount of processing time. In this work, vitrified-bonded diamond superabrasive stones with different grain diameters are developed. Then, multistage superfinishing is investigated by combining these stones. Results indicate that the multistage process is capable of producing a 2 nmRa surface, equivalent of a lapped surface in less than 10 min. To improve the process of multistage superfinishing, a removal amount estimation method is developed based on the real contact pressure calculation. The working area ratio of the stone was calculated by considering elastic deformation during superfinishing. The contact ratio of sapphire is calculated considering the roughness of the pre-finished surface and grain depth of cut. Accordingly, the real contact pressure is calculated to estimate the removal amount during superfinishing and finished surface roughness was expected.

DOI： 10.20965/ijat.2017.p0742

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

This paper describes an improved particle-excitation flow-control valve with high flow rate and controllability. The proposed control valve has a small volume, is lightweight, and can smoothly control the airflow through particle excitation. Pneumatic actuators, which have many advantages, are widely used in automation machine equipment and are expected to be used in robots. In general, such highly controllable pneumatic-control devices used as proportional valves are large-scale, heavy, and exhibit low response. We have developed a new flow-control valve called a particle-excitation flow-control valve, which has a simple structure with a lead zirconium titanate (PZT) resonance mode, large control-flow rate, and is lightweight. Further, this valve is expected to be highly responsive because it is driven by a PZT vibrator. In this study, we designed an experimental prototype to increase the maximum flow rate and measured its flow control and response characteristics. Moreover, we showed that this control valve has high controllability and control flow rate.

DOI： 10.1541/ieejsmas.137.32

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

The authors have previously developed a compact, light-weight air flow control valve, which realizes continuous flow control. The vibration produced by a piezoelectric device (PZT) was used to excite particles confined in a flow channel to control the valve opening for the developed control valve. Therefore, the voltage applied to the PZT can be changed to continuously control the flow rate. A new working principle was developed for the control valve to stabilize flow rate characteristics. Different types of particles were used to change the valve opening condition. A prototype was manufactured to demonstrate the effectiveness of the control valve.

DOI： 10.20965/ijat.2016.p0540

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Pneumatic actuators are widely used because they are lightweight and inexpensive. However, highly controllable devices for pneumatic actuators generally have large volume and low response and are heavy. We have developed the flow control valves that have highly controllable using PZT elements. These control valves can downsize the control valve with high response. Using a PZT transducer, we introduced a new mechanism of the control valve for stable continuous flow rate. In this report, we proposed a new mechanism to realize stable continuous flow with a PZT transducer. We designed prototype using a bolt-clamped Langevin transducer (BLT) and show the characteristics of the valve.

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DOI： 10.5739/jfps.46.7

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Pneumatic actuators have the potential to be downsized because they have simple structure. However, many control devices that can control pneumatic actuators continuously have large volume and weight. We have designed a flow-control valve driven by PZT vibrator. This control valve has small volume and low weight, and it can control air flow smoothly. This valve is suited to control small pneumatic actuators. The flow control valve that we propose uses resonance vibration with a PZT vibrator. The valve consists of an orifice plate, a PZT vibrator and iron particles that work as the poppet. From experimental flow quantity evaluation, this control valve controls air flow smoothly with low hysteresis at a large flow rate. In addition, this flow control valve achieves a maximum flow rate of 65 L/min under air pressure of 0.70 MPa. The results show that the valve has high controllability and can control a relatively large flow rate compared to its weight and size.

DOI： 10.1109/ULTSYM.2015.0134

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Abrasive Technology  

Our goal is the development of a design system for mechanochemical superabrasive stones containing both cBN and CeO₂ abrasives. As the first step, we have already developed a morphological structure model for the stone using fractal modeling techniques. As the second step, this paper describes the surface topography model for the stone. We have already proposed a surface topography model for the stone containing only cBN grains. This model can describe the surface topography with the same fractal dimension of grain distribution as the morphological structure model. Therefore, we have improved the model by preparation of the describing parameters for each grain and the changes in these parameters through the describing algorithm. As a result, the model bears resemblance to the real stone in topography and fractal dimension in each grain of the topography model is approximately equal to the morphological structure model.

DOI： 10.11420/jsat.57.453

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/10021320100?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

Excessive tool wear occurs when commercial steels are single-point diamond turned. Therefore, the development of diamond turnable steel is expected in the manufacture of molds for complex and precise optical components. As an initiate approach to this subject, various kinds of quenched and tempered steels were turned using single-crystal diamond tools, and tool wear measurement was made with a scanning electron microscopy. As a result, the various amounts of coner wear was observed by the diamond tool, and the width of wear was found to be different in a kind of steels. In order to clear up this cause, constituent phase analysis of the steels used in the turning experiments was carried out by X-ray diffraction. It gave that their microstructures differed considerably from steel to steel and were classified into four group, those are alpha-ferrite, alpha-ferrite + gamma-austenite, gamma-austenite, and alpha-ferrite + such carbides as Fe(3)C, Cr(23)C(6) and WC. On the basis of these results, the inductive inference methodology was applied to the tool wear measurement and phase analysis. From the results, the steel whose microstructure consists of particle carbide precipitation on alpha-ferrite matrix, e.g. JIS SK85, SUS420J2, SKS3 etc., suppresses diamond tool wear because the carbides prevent carbon diffusion into iron in turning of steel.

DOI： 10.2355/tetsutohagane.97.631

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CAMBRIDGE UNIV PRESS  

The elemental composition and microscopic-level shape of inclusions inside industrial materials are considered important factors in fracture analytical studies. In this work, a three-dimensional (3D) microscopic elemental analysis system based on a serial sectioning technique was developed to observe the internal structure of such materials. This 3D elemental mapping system included an X-ray fluorescence analyzer and a highprecision milling machine. Control signals for the X-ray observation process were automatically sent from a data I/O system synchronized with the precision positioning on the milling machine. Composite specimens were used to confirm the resolution and the accuracy of 3D models generated from this system. Each of the two specimens was composed of three metal wires of 0.5 mm diameter braided into a single twisted wire that was placed inside a metal pipe; the pipe was then filled with either epoxy resin or Sn. The milling machine was used to create a mirror-finish cross-sectional surface on these specimens, and elemental analyses were performed. The twisted wire structure was clearly observed in the resulting 3D models. This system enables automated investigation of the 3D internal structure of materials as well as the identification of their elemental components.

DOI： 10.1017/S143192761009450X

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Language：Japanese   Publisher：The Japan Society for Abrasive Technology  

Our goal is to develop a design system for mechanochemical superabrasive stone containing both cBN and CeO<SUB>2 </SUB>abrasives. As the first step of development, this paper describes the morphological structure model for the stone using fractal-modeling techniques. We have proposed two models to represent the conventional stone structure: the "agglomerate model of a plastic mixture" on the basis of the diffusion-limited aggregation algorithm and the "morphological model of a burnt stone" on the basis of the sandpile algorithm. In consideration of the characteristics of the mechanochemical stone, we have improved these models by adding the following procedures: the "cluster formation" algorithm and the "judgment of a bonded grain" algorithm. Both models bear resemblance to real wheels in the spatial distributions of both grains and the fractal dimensions in each grain of the real stone are approximately equivalent to those of the models.

DOI： 10.11420/jsat.54.557

CiNii Books

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

This paper describes a newly developed mechanochemical superabrasive stone containing reactive BaSO4 abrasive. A thermodynamic analysis suggested that BaSO4 reacts with Fe forming oxides. X-ray diffraction patterns revealed that scales that cover steels heated with BaSO4 abrasive consist of Fe3O4, alpha-Fe and BaS. On the basis of these results, vitrified diamond stones containing BaSO4 abrasive were manufactured and the effect of the BaSO4 abrasive on their performances was evaluated through the superfinishing of bearing steels. It was found that soft BaSO4 abrasive rubs the surface of hardened steel producing smooth surfaces with valleys. The stone reduces both the hardened layer depth and the compressive residual stress in the finished surface because of the formation of a thin white layer. The addition of BaSO4 abrasive improves the wear resistance of diamond stone because the dominant wear mechanism changes from carbon diffusion to oxidization of diamond. (C) 2009 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.precisioneng.2009.12.004

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：TECHNISCHE RUNDSCHAU EDITION COLIBRI LTD  

An appropriate phosphorous addition to electroless nickel deposits remarkably reduces tool wear in diamond turning. To understand the wear suppression mechanism of phosphorous addition, erosion tests simulating tool wear process and ab initio molecular dynamics calculations of interactions between diamond and Ni-P and Ni are carried out. The erosion tests show that carbon diffusion into the workpiece is reduced, and the ab initio calculations suggest that dissociation of carbon atoms on diamond surface due to the interaction with the workpiece is reduced. The results suggest that another possible additive to suppress tool wear can be found by the method proposed. (C) 2010 CIRP.

DOI： 10.1016/j.cirp.2010.03.058

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

A diamond stone is worn away faster than a cBN stone when superfinishing a steel workpiece, because of the carbon diffusion into iron. However, if such a wear mechanism can hardly work, it is expected that the wear of a diamond stone decreases. This paper describes two methods to suppress the carbon diffusion
that is, nitriding process of steels and addition of reactive BaSO4 abrasive to a diamond stone. When nitriding is applied to a steel, the face-centered cubic γ′ nitride, Fe4N, is formed at the steel surface. It acts as a barrier to deter the diffusion of carbon into iron. On the other hand, BaSO4 abrasive added to a diamond stone forms an oxide layer of Fe3O4 on the steel surface during superfinishing process. The formation of Fe3O4 accelerates the deoxidization by diamond. Then, the diamond stone wears not by carbon diffusion but deoxidization of Fe3O4. Superfinishing experiments have showed that both these methods improve the wear resistance of diamond stone.

DOI： 10.1299/kikaic.76.777

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

Nickel may erode diamond efficiently because carbon diffuses into nickel. We conducted erosion tests by bringing a pure nickel wire into contact with a diamond in a vacuum. The results revealed that as the erosion mark on the diamond surface became larger, the carbon content in the surface layer of the nickel wire increased. This implies that a diamond can be thermochemically polished by nickel. On the basis of this result, a diamond cutting tool was polished by bringing its rake face into contact with a nickel plate heated at 523 K for 6 h in a vacuum of 4.2 × 10-3 Pa. Approximately 4 nmthick layer was removed from the rake face. However, this technique had an unexpected adverse effect on the tool durability. The tool had low resistance to chipping of the cutting edge. Therefore, its tool life was extremely short compared with that of a mechanically polished diamond cutting tool. Thus, this implies that diamond cutting tools should be polished by a heated copper plate, that is, by the oxidation-deoxidization reaction discussed in our previous study.

DOI： 10.1299/kikaic.76.974

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG LONDON LTD  

This paper describes the application of prototype of the AFLEF to a peg-in hole task. This AFLEF is an active fixture and can fix any hole-work and position the fixed work at short range. We have combined the prototype of it and a 1-DOF inserting device with the RCC device into a new assembly system for such assembly task as a peg-in-hole task. However, there are two problems to realize this task. One is the "incomplete contact condition," and another is the modification of location of a hole-work to the insertion point. In this paper, in order to solve the former, the AFLEF has been newly equipped with two touch sensors to judge the contact condition and it can modify the contact condition to the complete contact. Moreover, in order to solve the latter, we propose the modification method without any vision sensor. In order to confirm the effectiveness of our proposing modifications of the contact condition and the hole-work&apos;s location, we have tried a peg-in-hole task with the assembly unit. As a result of this trial, although it took a little long time to finish a task, a task has been realized without failure.

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

This paper describes a new polishing method for diamond cutting tools. The method is based on the principle of oxidization of copper and deoxidization of copper oxide by carbon. A diamond tool was brought into contact with a copper plate, heated in air to a range of 323-523 K. The depth of the removed layer of diamond increased almost linearly with contact time and reached approximately 7 nm after 6 h. In this erosion process, pre-existing microcracks on the diamond surface were reduced. In comparison with the mechanically polished tool, the thermo-chemically polished tool was highly resistant to chipping and yielded a significant rise in tool life. (C) 2009 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.precisioneng.2009.01.004

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Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

The "active flexible fixture (AFLEF)" on plane level is an active and practical fixture, which can fix any work rigidly and position the fixed work at a few millimeters to correct the position error after gripping on plane level. This paper describes the application of the AFLEF to an assembly. We have combined the AFLEF and a 1-DOF inserting device with the RCC device, which controls a peg only to go down vertically, into a new assembly system for the assembly. However, there are two problems to realize it. One problem is the modification of the "incomplete contact" to the "complete contact" between a polygonal work and each contact-tip of the AFLEF. When four contact-tips of it grip the work, it is very rare that the plane contact is complete at all contact positions because of a rubber-slab and a free joint in the contact-tip. In this paper, we present the modification by using two touch sensors equipped each contact-tip with at both ends of it. Another problem is the method of positioning of a hole-work to the insertion point. Generally, the work is controlled with feedback from position sensor like vision sensor. However, we propose another method needing no vision sensor and taking advantage of the characteristic of the AFLEF in this paper. Therefore, in order to confirm the effectiveness of our proposing modifications of the contact condition and the holework's position, we have tried a peg-in-hole task with the assembly system at twenty times. As results of these trials, although it took a little long time to finish a task, all trials have been realized without failure.

DOI： 10.2493/jjspe.75.1134

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00362892381?from=CiNii

Authorship：Lead author   Publishing type：Research paper (scientific journal)  

Mechanochemical superabrasive stone containing CeO2 (i.e., cBN/CeO2 stone), which oxidizes steel, was developed and its characteristics were evaluated through the superfinishing of bearing steels.Experiments showed that cBN/CeO2 stone produced less subsurface damage and smaller compressive residual stress than cBN stone, and produced smooth surface with negative skewness because of the synergistic effect of the mechanical action of the cBN abrasive and chemical action of the CeO2 abrasive.Those results indicate that cBN/CeO2 stone can finish bearing steel surface with high wear resistance, fatigue strength, corrosion resistance, and sufficient oil dams.

DOI： 10.11420/jsat.53.499

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A new cutting tool was developed from ultra-fine-grain (&lt;100 nm), binderless cubic boron nitride (cBN) material fabricated by transforming hexagonal boron nitride to cBN by means of sintering under an ultra-high pressure of 10 GPa at 1800 degrees C. The cutting edges of the newly developed cBN tool can be made as sharp as those of single-crystal diamond tools. In this experiment, cBN and single-crystal diamond tools of the same shape were compared by precision cutting tests using stainless steel specimens and steel specimens coated with an electroless Ni-P layer. The surface roughness (R(z)) of specimen surfaces cut with the cBN tool by means of planing was approximately 100 nm for both the Ni-P-coated steel and stainless steel specimens. Though similar R(z) values were obtained for Ni-P layers cut by the cBN and diamond tools, an R(z) value exceeding 2000 nm was obtained for stainless steel cut by the diamond tool. High-precision surfaces with R(z) values of 50-100 nm were obtained for stainless steel specimens cut with the cBN tool under high-speed milling (942 m/min) conditions. These results indicate that the newly developed cBN tool is useful for the ultra-precision or precision cutting of ferrous materials. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jmatprotec.2009.05.023

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

One of the effective methods for obtaining an ultra-precision surface is utilization of the mechanochemical reaction that occurs at the interface between a tool and a workpiece. A thermodynamic analysis suggested that cerium oxide CeO(2) in contact with steel oxidizes the steel surface. Then, steel specimens embedded in CeO(2) powder were heated to 773 K in a vacuum, and their surfaces were closely analyzed by X-ray diffractometry. As a result, peaks of Fe(3)O(4) together with alpha-Fe were recognized by their diffraction patterns. On the basis of this finding, vitrified superabrasive stones containing CeO(2), i.e., cBN/CeO(2) stones, were made and their performances were evaluated through the superfinishing of bearing steels. Experiments showed that cBN/CeO(2) stone is superior in surface finish to conventional cBN stone because of the synergistic effect of the mechanical action of the cBN abrasive and chemical action of the CeO(2) abrasive. (c) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.precisioneng.2008.03.005

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

Casting defects in die casting materials are known as starting points of fatigue fractures. Therefore investigating their presence, sizes, and distributions are important for lifetime predictions of casting materials. In this paper, the size and the shape of casting defects inside aluminum die casting alloy were investigated by an automated three-dimensional information acquisition system based on consecutive precision milling and cross-sectional image recording. The main results obtained are as follows: (1) Two-dimensional color cross-sectional images were consecutively recorded in 4×4×5μm resolution for 20×14×20mm aluminum die casting specimen. (2) Casting defects were distinguishable in those images, and the regions of casting defects were extracted, and over 5000 individual regions were three-dimensionally reconstructed. (3) 90% of those regions were near sphere and relatively small in diameter (<100μm).

DOI： 10.2493/jjspe.74.991

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Other Link： https://jlc.jst.go.jp/DN/JALC/00356059622?from=CiNii

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

Recent advances in computer-aided engineering technologies need more accurate modelings techniques of three-dimensional shapes, internal structures of manufactures. In this paper, an automated system was newly developed to acquire the three-dimensional information. The system is based on consecutive precision machining and cross-sectional image recording. In the system, face milling by a single crystal diamond tool is used for high precision machining, and an optical microscope is used for cross-sectional image recording. By the system, following results were obtained: (1) Surface roughness of a resin embedded aluminum specimen was approximately 100nm p-v. (2) Two-dimensional color cross-sectional images of the specimen were consecutively recorded from top to bottom. (3) The aluminum was distinguishable from the surrounding resin in those images, and the resin was also distinguishable from air. (4) The aluminum and the resin were three-dimensionally reconstructed respectively from those images, and precise three-dimensional shapes and internal structures were acquired.

DOI： 10.2493/jjspe.74.587

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Venue：神奈川大学  

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Venue：米子コンベンションセンターBiG SHiP  

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Venue：理化学研究所 板橋分室  

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Venue：Okinawa, Japan  

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Venue：大阪大学  

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Venue：Portland Marriott Downtown Waterfront Hotel Portland, Oregon, USA  

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Venue：東京理科大学  

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Venue：東京大学  

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Venue：Crowne Plaza St. Paul – Riverfront, St. Paul, MN, USA  

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Venue：Hyatt Regency La Jolla at Aventine, San Diego, CA USA  

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Venue：Denver Marriott City Center Hotel, Denver, CO, USA  

Carbide precipitation on α-ferrite phase suppresses diamond tool wear in turning of steels because carbides prevent carbon diffusion into iron. In this paper, we investigate tool wear and surface integrity after turning of hot work die steel JIS SKD61: quenched and tempered steel, and carburized one. Results indicate that the carburized steel suppresses diamond tool wear, and improves surface integrity of ultraprecision cutting.

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Venue：Omni Hotel at CNN Center, Atlanta, GA USA  

Excessive tool wear occurs when commercial steel alloys are single-point diamond turned. Consequently, the development of a diamond-turnable steel is awaited in the manufacture of molds for high-precision, complex optical components. As a preliminary investigation, various quenched and tempered steels were turned using single-crystal diamond tools, and tool wear was measured using a scanning electron microscope. Maximum wear was observed at the tool nose, and its extent varied for different steels. To clarify the reasons for this, phase analysis of the steels used in the turning experiments was performed by X-ray diffraction. This analysis revealed that the steels had considerably different microstructures that could be classified into four broad groups: α-ferrite, α-ferrite + γ-austenite, γ-austenite, and α-ferrite + carbide compounds (e.g., Fe3C, Cr23C6, and WC). On the basis of these results, we analyzed whether a causal relationship existed between the microstructure of the steel and the nose wear of the diamond tool. To ensure unbiased analysis, an inductive inference technique known as C4.5 was applied to the tool wear measurement and phase analysis results. C4.5 generated valuable classification rules in the form of a decision tree that had branches associated with the matrix phases of the steels and leaves associated with the extent of nose wear. The tree described the following two rules: steels whose microstructures consist of α-ferrite and carbide phases (e.g., JIS SK5, JIS SKS3, and JIS SUS420J2) wear the tool nose slightly, whereas steels whose microstructures consist of α-ferrite, α-ferrite + γ-austenite, or γ-austenite wear the tool nose severely. Hence, the presence of carbon compounds in the α-ferrite matrix appears to be very effective in reducing the nose wear of diamond tools. Strong confirmation of this hypothesis was obtained by investigating the diamond turnabilities of steels in which carbon atoms remain as a solid solution in the martensite phase instead of forming carbon compounds. Turning experiments revealed that steels that are supersaturated with carbon atoms (i.e., quenched JIS SK5 and JIS SUS420J2) severely wore the tool nose. Therefore, it can be concluded that the formation of small carbon-compound particles that are uniformly dispersed within a continuous α-ferrite matrix suppresses nose wear of diamond tools.

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Venue：Pisa, Italy  

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Venue：京都大学  

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Venue：高エネルギー加速器研究機構  

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Venue：埼玉大学  

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Venue：埼玉大学  

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Venue：埼玉大学  

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Venue：関西大学  

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Venue：Monterey Marriott Hotel and the Monterey Conference Center Monterey, CA, USA  

Our goal is the development of the design system of the “mechano-chemical composite grinding wheel.” This wheel developed as a new composite grinding one is vitrified-bonded and compounded of super-hard abrasive grain like CBN and the “mechano-chemical” one like Cerium (IV) oxide (CeO2) replacing rouge in polishing of glass. The super finishing by the wheel has advantages of both abrasive grains. For example, the CBN-CeO2 composite wheel can realize the super finishing with higher efficiency than only CeO2 grains and lower roughness, less deformed layer and less scratch damage than only CBN grains. Clearly, however, it becomes more difficult to decide the production parameters like wheel composition, burning temperature, etc. for the composite wheel suitable for a given machining performance. Thus, in order to develop the design system, we have tried to clarify the relationship between the machining performance and the production parameters by incorporating the structure and surface topography of the composite wheel as parameter into it.This paper describes, as the first step of the development, the morphological structure model and the geometric surface model for the mechano-chemical composite grinding wheel using fractal modeling techniques. We have proposed two models to represent the conventional wheel’s structure: the “agglomerate model of a plastic mixture” representing a plastic mixture before the burning process of a wheel on the basis of the diffusion-limited aggregation algorithm and the “morphological model of a burnt wheel” representing the structure of the burnt wheel on the basis of the sandpile algorithm. In comparison with a conventional wheel, the characteristics of the composite wheel are as follows: CeO2 grains tend to agglomerate into some clusters and many grains miss being bonded to bond particles because the number of grain particles per a bond one is more. Thus, in the application of those models to the composite wheel, we have improved them by adding the following procedures: the “cluster formation” algorithm and the “judgment of a bonded grain” algorithm. On the other hand, we have also proposed the geometric modeling technique of a grinding wheel’s surface. It is based on the generating algorithms for random fractals such as midpoint displacement and successive random additions. We have constructed the geometric composite wheel’s surface model by setting parameters for each abrasive grain on the proposed geometric modeling technique. Both models were compared with the real wheels in structure and surface topography. As a result, both models bear resemblances to the real wheels in spatial and surface distributions of both grains and the average grain spacing, area percentage of grain occupation and fractal dimension in each grain of the real wheel are approximately equal to those of the models. Therefore, our models play an important role in the design of the developed composite wheels.

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Venue：Monterey Marriott Hotel and the Monterey Conference Center Monterey, CA, USA  

A new process chain for effective finishing of optical glass ultra-precision surface has been developed.One of the effective methods for obtaining ultra-precision surface is utilization of mechanochemical reaction that occurs at the interface between a tool and a workpiece.To realize such machining, new superabrasive stones have been developed, which have both chemical and mechanical actions.These new superabrasive stones differ from conventional ones.They contain cerium oxide CeO2 powder, which is softer than the workpiece but can chemically react with it, along with diamond grit.It is said that cerium oxide in contact with optical glass reacts with the glass surface.To confirm whether chemical reaction actually occurs, CeO2 stone was produced and its performance was evaluated through the superfinishing of optical glass.Experiments showed that the material removal rate of the CeO2 stone increased almost linearly and the wear rate of the CeO2 stone decreased almost linearly with an increase in the temperature of the superfinishing fluid; that is, the removal rate can be described by the Arrhenius equation.This means that CeO2 powder can also react chemically with the optical glass workpiece in the superfinishing process.The chemical action of the CeO2 powder produced good results for the surface finish.But the CeO2 stone cannot remove deep scratches produced by pre-finishing because the CeO2 powder is softer than the workpiece.To solve this problem, we optimized the pre-finishing process.A vitrified diamond stone and a vitrified diamond stone containing CeO2 powder (i.e., D stone and D/CeO2 stone) were examined through the superfinishing of optical glass.Experiments showed that the D stone was superior in removal rate and wear ratio than that of the D/CeO2 stone, and the D/CeO2 stone was superior in surface roughness and scratch depth than that of the D stone; that is, both had their strong and weak points.To optimize the pre-finishing process, simplex method was used to maximize the removal rate, which was subject to smaller scratch depth, better roughness, and smaller stone wear.After optimization, D/CeO2 was chosen as the pre-finishing process.The D/CeO2 stone produced less scratch than the D stone and removed about the same amount of optical glass as the D stone.The results are as follows:The D/CeO2 stone produces smooth surface with less scratch, good roughness, and small stone wear, and high removal rate; that is, the D/CeO2 stone is suitable for pre-finishing.The CeO2 stone reacts with optical glass surface and produces a smooth surface with less scratch that is suitable for finishing process of reflecting mirrors.Add to these results, the total finishing time of the process is shorter than five minutes.Consequently, it is concluded that the process chain has a superior finishing performance.

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Venue：神戸大学  

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Venue：神戸大学  

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Venue：大阪電気通信大学  

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Venue：千里LSC  

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Venue：中央大学  

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Venue：中央大学  

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Venue：中央大学  

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Venue：関西大学  

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Venue：理化学研究所  

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Venue：理化学研究所  

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Venue：Portland Marriott Downtown Waterfront Hotel Portland, Oregon, USA  

Interfacial reaction machining is an effective method for achieving high surface accuracy, good surface finish, and low subsurface damage. To realize such machining, a new superabrasive stone has been developed, which has both chemical and mechanical actions. This new superabrasive stone differs from conventional ones. It contains barium sulfate BaSO4 powder, which is softer than the workpiece but can chemically react with it, along with diamond grit.According to the thermodynamic analysis, when BaSO4 is in contact with steel, it oxidizes the steel surface. To confirm whether this chemical reaction actually occurs, steel specimens embedded in BaSO4 powder were heated in a vacuum, and their surfaces were closely analyzed by X-ray diffractometry. Peaks of Fe3O4 together with -Fe were observed in their diffraction patterns. Therefore, the derived reaction can be represented by the following chemical equation:BaSO4 + 3Fe → Fe3O4 + BaSOn the basis of this finding, a vitrified diamond stone containing BaSO4 powder (i.e., D/BaSO4 stone) was produced and its performance was evaluated through the superfinishing of bearing steels. Experiments showed that the material removal rate of the D/BaSO4 stone increased almost linearly with an increase in the temperature of the superfinishing fluid; that is, the removal rate can be described by the Arrhenius equation. This means that BaSO4 powder can also react chemically with the steel workpiece in the superfinishing process. The chemical action of the BaSO4 powder yielded the following good results for the surface finish.First, the D/BaSO4 stone produced a smooth surface with negative skewness that is suitable for bearing races. Second, the D/BaSO4 stone reduced both the hardened layer depth and the compressive residual stress in the finished surfaces. Finally, the finishing ratio of the D/BaSO4 stone was five times larger than that of conventional diamond stone because of its high resistance to wear. Consequently, it is concluded that the D/BaSO4 stone has a superior finishing performance than that of diamond stone.

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Venue：Portland Marriott Downtown Waterfront Hotel Portland, Oregon, USA  

An automated three-dimensional internal information acquisition system based on consecutive precision machining and high-resolution cross-sectional observation was developed.The system enabled three-dimensional analyses of casting defects in a die casting alloy specimen, and three-dimensional microstructure observation of biological samples containing hard tissues.Precise detection of internal defects inside metallic material specimens and microscopic internal structure observation of biological samples are desired.Destructive inspections provides more detailed and accurate information of specimens than nondestructive tests, though, they requires considerable time to prepare specimens, and to align cross-sectional information to reconstruct three-dimensional information.The time required for specimen preparation and three-dimensional alignment should be reduced.To achieve this, automatic and sequential high-precision cross-section generations and cross-sectional information acquisitions are needed.An automated system was developed to acquire three-dimensional information.The system is based on consecutive precision machining and cross-sectional image recording.In the system, face milling by a single crystal diamond tools is used for high precision machining, and an optical microscope is used for cross-sectional image recording.By the system, following results were obtained.Cutting accuracy and information acquisition accuracy was tested and both of their errors, which are main cause of acquisition information errors, were below 1 μm.Surface roughness of a resin embedded aluminum specimen after cutting was approximately 100nm p-v.Two-dimensional color cross-sectional images of the specimen were consecutively recorded from top to bottom.In those images, the aluminum was distinguishable from the surrounding resin, and the resin was also distinguishable from air.The aluminum and the resin were three-dimensionally reconstructed respectively from those images, and precise three-dimensional shapes and internal structures were acquired.In addition, compared to conventional nondestructive test, the information acquired by the system includes less skews, less artifacts, and has high spatial resolution.The size and the shape of casting defects inside aluminum die casting alloy specimen, which has many casting defects inside, were also investigated by the system.Three-dimensional information of whole specimen was acquired less than 10 μm resolution.Casting defects inside the specimen were distinguishable in color cross-sectional images, and the regions of casting defects were extracted.Over 5000 individual regions of casting defects were three-dimensionally reconstructed, and those size and shapes were examined.To acquire biological samples’ internal structure like lifelike shape, hard tissues and soft tissues should not be separated before cutting.By the system, hard tissues like bones were mirror-like finished and internal structures of hard tissues were acquired.Three-dimensional internal structure of hard tissues were reconstructed and visualized by the system.In addition, three-dimensional internal structures of a frozen specimen, which contains hard tissues and soft tissues, were also acquired by the system.Both soft tissues and hard tissues of the specimen were three-dimensionally visualized.

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Venue：東北大学  

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Venue：東北大学  

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Venue：滋賀県立大学  

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Venue：堺市産業振興センター  

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Country：Japan

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Country：Japan

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