Faculty Profiles - NARAHARA Hiroyuki

Papers - NARAHARA Hiroyuki

Division display1 - 20 of about 225／ All the affair displays >>

Simplified Prediction of Melt Pool Shape in Metal Additive Manufacturing Using Maraging Steel Reviewed International journal

T. Fukunaga , H. Narahara

International Journal of Automation Technology ( Fuji Technology Press Ltd. ) 16 ( 5 ) 609 - 614 2022.09

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

This paper describes a method to represent and predict the melting and solidifying shape of metal powder materials in the selective laser melting (SLM) method of metal addition manufacturing using a small number of physical properties. This is a processing method to complete a three-dimensional modeling object by layer-by-layer stacking. A laser beam is used to create objects with minimal voids and distortion by appropriately setting the scanning speed, output intensity, spot diameter, hatch spacing, and other conditions. Repeating actual experiments to determine the optimal build conditions increases the cost of operating the machine, such as electricity and labor, and the cost of materials when a modeling failure occurs. In recent years, attempts have been made to determine the optimal build conditions by analyzing the melting and solidification phenomena of metallic materials through precise simulations. However, it is necessary to set many physical property values as the parameters. Many physical property values are difficult to measure, and if these values are incorrect, the analysis results can differ significantly. In this study, a theoretical model for predicting the cross-sectional area and cross-sectional thickness of the melt pool using a single-track laser was developed using a small number of physical properties, such as melting point, thermal conductivity, and latent heat. To further examine the validity of the theoretical model, experiments were conducted for comparison purposes. In this experiment, 5 × 1 × 1 mm rectangular specimens were stacked and fabricated by a metal additive manufacturing machine using different laser beam irradiation conditions. The fabricated samples were cut, polished, and etched with nital, and the melt pool shapes were measured. Finally, experimental and theoretical values were compared to confirm the validity of the constructed theoretical model. This indicates that the proposed model can predict the melt pool shape.

DOI： 10.20965/ijat.2022.p0609

Scopus

CiNii Research

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85137414758&origin=inward

Improvement in the permeability characteristics of injection mold fabricated by additive manufacturing and irradiated by electron beams Reviewed International journal

Koresawa Hiroshi, Fujimaru Hironobu, Narahara Hiroyuki

International Journal of Automation Technology ( Fuji Technology Press Ltd. ) 11 ( 1 ) 97 - 103 2017.01

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

This paper describes a metal mold with permeability fabricated by metal laser sintering with high-speed milling, which is an additive manufacturing method, and discusses the improvement in permeability. In this method, the sintered body is produced with gas exhaust tubes based on the porous structure. To maintain permeability, ensuring that the gas exhaust tube is not blocked is essential. Blockages may occur because of reasons such as the deformation of the gas exhaust tube due to the milling process during fabrication and generation of mold deposits within the gas exhaust tube during injection molding. In this research, by irradiating the surface of a sintered body, with a gas exhaust tube, by an electron beam, water repellency attributed to the reduction in surface free energy and recovery of permeability are confirmed. Further, in a fundamental experiment with an injection molding machine, the permeability of a permeable sintered body irradiated an electron beam increased by approximately 2.8 times as compared to the permeability of a sintered body that was not irradiated.

DOI： 10.20965/ijat.2017.p0097

Scopus

CiNii Article

CiNii Research

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85010845194&origin=inward

Improvement and Evaluation of the Interlaminar Bonding Strength of FDM Parts by Atmospheric-Pressure Plasma Reviewed International journal

Narahara H., Shirahama Y., Koresawa H.

Procedia CIRP 42 754 - 759 2016.01

Low-energy injection molding process by a mold with permeability fabricated by additive manufacturing Reviewed

10 ( 1 ) 101 - 105 2016.01

Permeability performance on porous structure of injection mold fabricated by metal laser sintering combined with high speed milling Reviewed International journal

6 ( 5 ) 576 - 583 2012.09

Reaction Heat Effects on Initial Linear Shrinkage and Deformation in Stereolithography Reviewed International journal

Hiroyuki Narahara,Fumiki Tanaka(Hokkaido Univ.),Takeshi Kishinami(Hokkaido Univ.),Satoru Igarashi(Hokkaido Univ.),Katsumasa Saito(Gunma Polytech College)

Rapid Prototyping Journal 5 ( 3 ) 120 - 128 1999.04

Study of Support Shape in Metal Additive Manufacturing by Evaluation of Strain Energy during Support Removal

Sato Rintaro, Narahara Hiroyuki, Koresawa Hiroshi

Proceedings of JSPE Semestrial Meeting ( The Japan Society for Precision Engineering ) 2024S ( 0 ) 525 - 526 2024.02

金属積層造形における造形環境が造形品質に与える影響

郭笑蕾, 楢原弘之, 是澤宏之

精密工学会学術講演会講演論文集 ( 公益社団法人精密工学会 ) 2024S ( 0 ) 527 - 528 2024.02

Authorship：Last author,　Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

近年，金属積層造形法は革新な技術として注目され，幅広く応用されている．造形する際にレーザー光で局所的に急激な温度変化を繰り返すため，熱ひずみが発生し，熱変形の抑制は金属積層造形における重要な課題の一つとなる．本研究は金属積層造形の造形品質を向上させるため，造形環境を研究対象とする．造形室内の雰囲気ガスなどの条件を考慮した造形実験を行い，造形環境の違いによる造形物の変形に与える影響について調べる．

DOI： 10.11522/pscjspe.2024s.0_527

CiNii Research

Research on molding defects due to deformation of injection molds

Michihira Kazuki, Isii Masaki, Koresawa Hiroshi, Narahara Hiroyuki, Murakami Sunao

Proceedings of JSPE Semestrial Meeting ( The Japan Society for Precision Engineering ) 2024S ( 0 ) 201 - 202 2024.02

Effect of Processing Conditions on Mechanical Properties of Snap-Fit with Different Aspect Ratios Fabricated by FDM Reviewed

TAGUCHI Hiroyuki, KUNIMATSU Yohei, NARAHARA Hiroyuki

Journal of the Japan Society for Precision Engineering ( The Japan Society for Precision Engineering ) 90 ( 4 ) 376 - 382 2024.01

Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal)

Snap-fit is one of the most important joining methods for plastic products. Since the function and performance of snap-fit often require sensitivity evaluation, prototyping before mass production is important. FDM is one of Additive Manufacturing, and FDM is considered to be suitable for snap-fit prototyping. On the other hand, since the mechanical properties of FDM vary depending on the processing conditions, it is important to verify the relationship between the processing conditions and snap-fit mechanical properties. In addition, in recent years, plastic products have become smaller in some areas. In the case of cantilever-type snap-fit, it is necessary to evaluate the effect of shear deformation as the aspect ratio decreases. In this study, the effect of processing conditions on mechanical properties of snap-fit with different aspect ratios fabricated by FDM were investigated.

DOI： 10.2493/jjspe.90.376

Scopus

CiNii Research

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85190416649&origin=inward

Quantitative Evaluation of Deformation of Metal Additive Manufacturing by Changing Built Part Posture

GUO Xiaolei, Sakamoto Ryoko, Narahara Hiroyuki, Koresawa Hiroshi

Proceedings of JSPE Semestrial Meeting ( The Japan Society for Precision Engineering ) 2023A ( 0 ) 647 - 648 2023.08

射出成形金型の成形中の変形挙動に関する研究

道平和樹, 是澤宏之, 楢原弘之, 村上直

精密工学会学術講演会講演論文集 ( 公益社団法人精密工学会 ) 2023A ( 0 ) 721 - 722 2023.08

Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

射出成形法で用いる金型は弾性体であるため，成形中に樹脂による大きな圧力で変形が生じる．しかし，この変形挙動を詳しく解明できていない．よって様々な成形不良が生じている．本報ではその中でバリという成形不良に着目する．バリは樹脂圧力により金型分割面に間隙が生じることが一つの原因である．よって射出成形機の変形も考慮した構造解析を用いて金型分割面に生じる間隙を求め，検討した．

DOI： 10.11522/pscjspe.2023a.0_721

CiNii Research

AMで作成したスナップフィット部品曲げ試験時の積層パターン影響調査

國松遙平, 楢原弘之, 是澤宏之, 田口宏之

精密工学会学術講演会講演論文集 ( 公益社団法人精密工学会 ) 2023A ( 0 ) 654 - 655 2023.08

Authorship：Last author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

スナップフィットとは、接合時梁部分がたわみ、材料の弾性を利用して元の形状に戻り、接合する方法である。これは環境に配慮した方法であり、様々な用途で使われる。私の研究では、AM品をスナップフィット部品の試作品として実用化することを最終目標としている。しかし、AMで作成時、積層パターンによってたわみ量が変動すると考えられる。そこで本研究では、曲げ試験を行い積層パターンがたわみ量に及ぼす影響を調査した。

DOI： 10.11522/pscjspe.2023a.0_654

CiNii Research

Effect of FDM Processing Conditions on Snap-Fit Characteristic in Assembly Reviewed

Taguchi Hiroyuki, Kunimatsu Yohei, Narahara Hiroyuki

International Journal of Automation Technology ( Fuji Technology Press Ltd. ) 17 ( 4 ) 326 - 334 2023.07

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

Snap-fit allows plastic products to have assembly and disassembly capabilities without the use of screws, bolts, or other additional parts. For this reason, snap-fit is used in all kinds of plastic products from stationery to automotive parts. Because the mechanical and other functions of a snap-fit are greatly affected by its shape and material properties, it is desirable to fully evaluate them at the design stage. In addition, as the assembly and disassembly of products by snap-fit is generally performed by people, it is important to evaluate not only virtually but also with actual plastic parts. Therefore, there is a strong need to make a prototype and evaluate the feel of the product during assembling and disassembling, before finalizing on the shape and materials. In the past, making precise prototype required expensive molds, but in recent years, additive manufacturing has made it possible to make prototype efficiently and at low cost. In additive manufacturing, fused deposition modeling (FDM) is considered suitable for snap-fit prototype because it can use the same materials as mass-produced products. Thus, it may be possible to make a snap-fit prototype with rigidity, strength, and other characteristics similar to those of mass-produced products. However, FDM has various processing conditions such as tool path, nozzle temperature, and height of one layer. They are expected to have a significant effect on the snap-fit characteristics. Snap-fit is required to meet various requirements depending on the plastic products. The requirements can be divided into three major categories: in assembly, in disassembly, and when to use. In this study, we investigated the effect of FDM processing conditions on snap-fit characteristic in assembly.

DOI： 10.20965/ijat.2023.p0326

Scopus

CiNii Research

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85164914649&origin=inward

Tool condition monitoring method by anomaly segmentation of time-frequency images using acoustic emission in small hole drilling Reviewed

NAKANO Taro, KORESAWA Hiroshi, NARAHARA Hiroyuki

Journal of Advanced Mechanical Design, Systems, and Manufacturing ( The Japan Society of Mechanical Engineers ) 17 ( 3 ) JAMDSM0034 - JAMDSM0034 2023.06

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

Tool wear leads to a reduction in dimensional accuracy and surface quality, as well as unexpected sudden tool failure. A broken tool can cause irreparable damage to an expensive workpiece, resulting in increased operating costs and production delays. Since the mechanical strength of small-diameter drills is inadequate for the load and prone to breakage, tool condition monitoring and diagnosis is important to prevent sudden tool breakage, increase productivity, and promote automation in machining process. The present work is aimed to investigate a tool condition monitoring method based on the analysis of acoustic emission (AE) signals emitted during small-hole drilling. We propose DDM (Deep feature Distribution Modeling), a method for image-level anomaly detection and anomaly segmentation in time-series signal analysis. The peck drilling experiments on SKD61 steels were performed with high-speed steel (HSS) drills. The continuous wavelet transform (CWT) was applied to generate time-frequency (TF) image of the AE signals during the drilling process. The TF images were quantified as anomaly scores using the DDM, which establishes normality by fitting a multivariate Gaussian (MVG) to pre-trained deep features. The anomaly detection capability of the DDM and the convolutional autoencoder (CAE) was compared using dummy data for validation. The digital microscope was employed to measure tool wear. Chip morphology was also observed by the laser microscopy. As the tool wear progressed, the anomaly score increased or decreased, with several sharp increases observed between holes 3805 and 3869 just prior to tool failure. An increase in the width of the shear layer spacing of the chips was also observed just prior to failure. Changes in the anomaly score associated with tool wear were more clearly identified by creating anomaly maps. The present investigation shows that waveform processing of AE signals using the CWT and anomaly detection based on the DDM are efficient methods for tool condition monitoring. Our proposed approach makes it possible to visualize the differences in anomaly states using a more subdivided layer context by generating multiple anomaly maps with deep feature vectors obtained from multiple layers.

DOI： 10.1299/jamdsm.2023jamdsm0034

Scopus

CiNii Research

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85164247193&origin=inward

熱溶解積層法用フィラメントの強度向上に関する基礎研究

日高明, 是澤宏之, 楢原弘之

精密工学会学術講演会講演論文集 ( 公益社団法人精密工学会 ) 2023S ( 0 ) 226 - 227 2023.03

Preface Reviewed International journal

NARAHARA Hiroyuki, TANAKA Ryutaro

Journal of Advanced Mechanical Design, Systems, and Manufacturing ( The Japan Society of Mechanical Engineers ) 17 ( 1 ) JAMDSM0001 - JAMDSM0001 2023.01

Magnetic Domain Observation of Milled Nanocrystalline Alloy Powder Reviewed

Takezawa M., Nagaki T., Motozuka S., Sasaki I., Ando Y., Narahara H., Mori N., Shikayama T., Mukai S., Maeda S., Sakima S., Ishii T.

IEEE Transactions on Magnetics 59 ( 11 ) 2023.01

Microstructure and Magnetic Characterization on Ball-Milled Fe-Based Nanocrystalline Alloy Sheet Reviewed International journal

Nagata S., Horibe Y., Hiramoto S., Narahara H., Mori N., Sasaki I., Takezawa M., Ando Y., Shikayama T., Mukai S., Maeda S., Sakima S., Ishii T., Motozuka S.

Digests of the Intermag Conference 2023-May 2023.01

Microstructure and Magnetic Characterization on Ball-milled Fe-based Nanocrystalline Alloy Sheet Reviewed International journal

Nagata S., Horibe Y., Hiramoto S., Narahara H., Mori N., Sasaki I., Takezawa M., Ando Y., Shikayama T., Mukai S., Maeda S., Sakima S., Ishii T., Motozuka S.

2023 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2023 - Proceedings 2023.01

　PREV- NEXT 　

<NARAHARA Hiroyuki>

Papers - NARAHARA Hiroyuki