研究者詳細 - 柿沼　康弘

論文 - 柿沼　康弘

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指向性エネルギー堆積法における軟磁性造形物の磁気特性と結晶粒構造評価

金丸聡真, 小池綾, 柿沼康弘, 廣野陽子, 森貴則

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） 2021A （ 0 ） 326 - 327 2021年09月

複雑形状部品を一体造形ができる付加製造技術は，自動車産業においても注目を集めている．本研究は指向性エネルギー堆積法を用いた電気自動車のモータ製造法の確立を目指し，磁芯に利用される軟磁性材料FeSi，FeCoVを用いた造形物の磁性と結晶粒組織を評価した．安定造形が可能な造形パラメータを同定し，FeCoV造形物についてレーザ出力を増加させることで鉄損の原因となる保磁力を低めることができた．

サーボ情報とAE信号を用いた光学ガラスの超精密研削における加工状態監視

栗山充, 左高志織, 柿沼康弘

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） 2021S （ 0 ） 283 - 284 2021年03月

大口径の光学ガラスレンズの形状創成において，ガラスを割らずに加工する延性モード研削の適用とその効率向上が求められている．安定した延性モード研削を行うためには，研削加工中に延性／脆性モードを判別する技術が必要不可欠である．そこで，本研究では，工作物主軸に組み込んだAEセンサと各軸のサーボ情報を用いた加工状態監視手法を提案した．信号波形を解析し，加工状態に応じて各信号に生じる特徴を明らかにした．

Development of Automatic Chatter Suppression System in Parallel Milling by Real-Time Spindle Speed Control with Observer-Based Chatter Monitoring

Yamato S., Nakanishi K., Suzuki N., Kakinuma Y.

International Journal of Precision Engineering and Manufacturing 22 （ 2 ） 227 - 240 2021年02月

ISSN 22347593

To maximize the potential for high material removal rates in simultaneous processes such as parallel milling, developing strategies for successful chatter suppression/avoidance is an important concern for manufacturers. In this study, the effectiveness of the spindle speed difference method (SDM) for chatter suppression is discussed in a parallel end-milling process where a flexible workpiece is machined by two tools rotating in opposite direction. The process model is developed, considering that the dynamic variation due to the regenerative effect occurs on a plane perpendicular to the tool axis direction. Through the process simulations and the experiments, this study provides informative discussion for comprehending the process behavior. Additionally, a real-time active chatter suppression system with adaptive SDM, where the spindle speed difference is sequentially optimized during the process according to the tracked chatter frequency, is developed by integrating a chatter monitoring system based on sensorless cutting force estimation with sliding discrete Fourier transform. The results show that the developed real-time adaptive system of spindle speed suppresses chatter vibrations more effectively than non-adaptive SDM system; hence, the integrated system can contribute self-optimizing machining systems oriented to Industry 4.0.

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Vibration analysis and cutting simulation of structural nonlinearity for machine tool

Irino N., Imabeppu Y., Higuchi Y., Shinba Y., Kawai K., Suzuki N., Kaneko J., Kakinuma Y., Mori M.

CIRP Annals 70 （ 1 ） 317 - 320 2021年01月

ISSN 00078506

The dynamic behavior of a machine tool is affected by the forces applied to the structure. However, cutting processes have been analyzed considering the linear systems in most of the studies so far. In this study, a machine tool structure was excited by using an electromagnetic shaker and the force-dependant frequency response characteristics were measured. Based on the measured result, the nonlinear characteristics of the machine tool structure was identified, and a machine tool with the nonlinear characteristics was mathematically reproduced, which enabled to analyse the nonlinear frequency response characteristics and simulate cutting processes.

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Development of an electro-adhesive hand with the function of contact and slip detection

Hioki Y., Nishimura R., Anzai H., Sakurai K., Nagatsuma A., Aoyama T., Kakinuma Y.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 （一般社団法人日本機械学会） 2021.10 （ 0 ） 637 - 639 2021年

In this study, Electro-Adhesive Gel Sheet (EAGS) was attached to a robot hand and used as a gripper. Electro-Adhesive Gel (EAG) is a functional elastomer which can change surface adhesiveness depending on an electric field. EAGS is a sheet of EAG fabricated on a flexible electrode substrate. It is confirmed that the electrical current flow inside EAGS is changed when the robot hand with EAGS (EA hand) touches a grounded metal object or slips on it. By applying these current characteristics, the applicability of contact detection and slip detection is investigated to monitor gripping status in robot hand. From the results, EA hand can detect not only the contact but also lifting the object from the base plate. Furthermore, slipping can be suppressed by adjusting an applied potential difference of the electrodes according to the slip detection.

Basic study of fabrication conditions for foam stainless in directed energy deposition

Takeuchi T., Koike R., Kakinuma Y., Kondo M., Oda Y., Mori T.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 （一般社団法人日本機械学会） 2021.10 （ 0 ） 677 - 682 2021年

Directed energy deposition (DED) is one of additive manufacturing processes attracting attention from various industries. Foam metal is a material having beneficial characteristics, but is difficult to produce with conventional manufacturing system. This study proposes a simple foam metal fabrication method by applying DED. The proposed method produces foam stainless alloy in DED by adding a foaming agent, titanium hydride (TiH2), into the powder material. This study evaluates the foaming behavior of porous stainless in DED by changing the particle size of TiH2 and the number of layers per line, and obtains the optimal number of layers to improve the porosity dispersion.

Enhancement of force control performance of macro-micro system based polishing robot with gravity compensation

Ogawa S., Koto K., Tsukada T., Kakinuma Y.

Proceedings of the ASME 2021 16th International Manufacturing Science and Engineering Conference, MSEC 2021 1 2021年

In a fine mold manufacturing process, the polishing process plays an important role in enhancing the surface quality and is performed manually by skilled workers. However, there are many problems such as decrease in skilled workers, health hazards due to scattering of abrasives, and difference in surface quality due to difference in the proficiency. Hence, there is a strong demand for automation of the polishing process at present. In this research, a robot polishing system that applies macro-micro mechanism is proposed. The functional polishing module of the end effector is developed and attached to the hand of the serial link robot. Tool path and posture are controlled in a serial link robot as a macro mechanism, and polishing force and tool rotation speed are controlled in the developed polishing module as micro mechanism. This mechanism ideally controls position, force, and rotation speed at the same time. An interlocking control system for position and force has already been constructed. In this paper, we constructed gravity compensation and evaluated the force control performance of the constructed system. Through the evaluation, the followability of the estimated reaction force to the command force and the validity of the actual force behavior measured by the force sensor were evaluated.

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Study on cutting mechanism of mold steel in ultrasonic elliptical vibration cutting with textured tool

Ito H., Maeng S., Min S., Kakinuma Y.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 （一般社団法人日本機械学会） 2021.10 （ 0 ） 234 - 237 2021年

Machining of mold steel like STAVAX is still challenging due to significant tool wear. The ultrasonic elliptical vibration cutting (UEVC) that enables dramatic reduction of cutting force is considered as a potential solution. Tool-texturing on the rake face to reduce the friction coefficient between chips and the tool can be another solution as well. Hence, combining these two approaches may provide synergetic effect to further reduce the cutting force. In order to understand this effect, chip formation using these approaches is experimentally investigated. Chip morphology is totally different whether to use UEVC and textured tools. It was shown that the perpendicular pattern to the chip flow direction may enhance the chip-lifting effect during UEVC. Thus, upward force is applied to the workpiece, which causes reduction of thrust force.

Powder velocity-based nozzle design for directed energy deposition

Takemura K., Koike R., Kakinuma Y., Yamazaki K., Mori T., Hirono Y.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 （一般社団法人日本機械学会） 2021.10 （ 0 ） 458 - 461 2021年

Directed energy deposition (DED), which is one of the metal-powder additive manufacturing processes, is a promising method suitable for repairing. Because the carrier gas that transports the metal powder and the shield gas that protects the optical system are supplied in DED, it is difficult to estimate the transport of metal powder due to the complex turbulence around the processing point, resulting the powder supply efficiency gets lowered. This study computationally analyzed the fluid dynamics of two types of DED nozzles for improving the powder supply efficiency by changing the number of powder channels, working distance and channel diameter.

Performance evaluation of robot polishing in macro-micro system based polishing robot

Koto K., Tukada T., Ogawa S., Kakinuma Y.

Proceedings of the ASME 2021 16th International Manufacturing Science and Engineering Conference, MSEC 2021 1 2021年

Polishing is an important process performed in the finishing and repair processes of mechanical parts and is still a manual work of skilled workers. However, in addition to the time and cost required for manual polishing, there are also problems such as a decrease in the number of workers and health hazards due to dust generated during polishing. From these problems, the demand for automatic polishing is increasing at manufacturing sites. To automate polishing process, a macro-micro system based polishing robot which consists of a functional end-effector and industrial robot has been proposed. Regarding end effectors, mechanical design aiming for high rigidity and motion control methods for keeping the contact force constant is being researched. Meanwhile, the tool rotation speed of the spindle is independently controlled typically. Therefore, in this research, a functional polishing module capable of polishing force control and tool rotation control according to the tool feed rate is developed as the end effector. For the polishing automation, the macro-micro system based polishing robot is constructed attaching the polishing module to the industrial robot. From the viewpoint of Preston’s law, the effectiveness of the robot polishing is investigated through polishing experiments and measuring the shape of the polished surface.

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Mechanical property evaluation of the SLM support structure and lattice structure of SUS316L

Okochi W., Ikeda Y., Koike R., Mori T., Hirono Y., Maki T., Takaki K., Kakinuma Y.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 452 - 455 2021年

Selective laser melting (SLM) is one of the additive manufacturing (AM) methods which is applicable to metal. Although this technology enables to form complex inner shapes such as lattice structure, steep temperature gradients due to local laser irradiation and uneven heat conduction during the process may cause bending and cracking of the product. In this study, the influence of laser power and scanning speed on the mechanical characteristics of the support structure and lattice structure formed by SLM is investigated. In the tensile test of the support structure, a positive correlation with volumetric energy density was confirmed. In the compression test of the lattice structure, it was clear that larger amount of heat energy from the laser makes struts of lattice structure thicker and its Young's modulus higher.

Machine learning-based shape error estimation in micromilling by using motor current

Mizuhara K., Nakamichi D., Yanagihara W., Kakinuma Y.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 （一般社団法人日本機械学会） 2021.10 （ 0 ） 594 - 596 2021年

The requirement for Mass production of Microlens array (MLA) mold is increasing. MLA molds are manufactured by 5-axis ultra-precision machining center using an ultra-small diameter end mill. Since visual examination is not good at judging quality of product while machining, the development of effective process monitoring technology is required. The ultra-precision machining center used in this study employs a linear motor and has low sliding resistance while machining. Therefore, machining information is directly reflected in servo information. Focusing on this point, we developed a machine learning-based shape error estimation model using servomotor current alone and discussed its usefulness.

Fabrication of dispersion engineered ultrahigh-Q crystalline optical microresonator for broad-bandwidth optical parametric oscillation

Fujii S., Wada K., Kakinuma Y., Tanabe T.

Proceedings of SPIE - The International Society for Optical Engineering （SPIE-INT SOC OPTICAL ENGINEERING） 11672 2021年

ISSN 0277786X

We demonstrate the all-precision-machining fabrication of ultrahigh-quality-factor (Q) crystalline optical microresonators. The obtained Q exceeds 100 million for both magnesium fluoride (MgF2) and calcium fluoride (CaF2) materials. This constitutes the highest Q factor obtained for whispering gallery mode crystalline microresonators fabricated solely by ultra-precision machining. We also achieve octave-wide optical parametric oscillation using an MgF2 resonator fabricated with a computer-controlled machining process. This method readily enables advanced dispersion engineering for optical parametric oscillation and makes it possible to explore microcavity nonlinear optics and quantum optics without the need for skilled manual polishing techniques.

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Experimental Evaluation of Reaction Induced Slurry Assisted Grinding for BK7 Optical Glass

Kawasato T., Hamazono K., Fukuta M., Tanaka K., Nagano M., Kato H., Kakinuma Y.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 287 - 290 2021年

A more accurate and more efficient grinding method for optical glasses is demanded as high-resolution imaging devices become more popular. We propose a reaction-induced-slurry-assisted (RISA) grinding method as a chemical mechanical grinding method using cerium oxide slurry instead of ordinary coolant. In this study, the grinding performance of RISA grinding for BK7 optical glass is experimentally evaluated from the viewpoints of sub-surface damage and repeatability of ductile regime grinding at various wheel feed rates. From the grinding tests, RISA grinding causes less sub-surface damages and successfully generates ductile regime surface repeatedly under 3.0 mm/min wheel feed rate.

Basic study on electro-adhesive surface applying 3-dimensional micro structures

Yamada Soichiro, Koike Ryo, Arano Shintaro, Kakinuma Yasuhiro, Aoyama Tojiro

International Journal of Automation Technology （Fuji Technology Press） 10 （ 1 ） 48 - 54 2016年

研究論文（学術雑誌）, ISSN 1881-7629

Electro Adhesive Gel (EAG) has the unique characteristic of changing its surface adhesive property with the intensity of the electrical field applied. This propertymakes EAG useful in applications to fixing devices and mechanical brakes. Although its adhesion performance depends on the distribution of the electrorheological particles in the EAG, it is difficult to arrange the particle distribution uniformly in a wide area from the perspective of production process. In this study, a novel functional elastomer that has the same function as EAG is developed, Electro Adhesive Surface (EAS). In EAS, micro photolithography is used to fabricate strut pyramids distributed uniformly on a substrate, and then silicone gel is poured into the structure. When an electrical field is applied, the silicone gel rises to the tops of the pyramids formed by the struts, and adhesion occurs to an object on EAS. To determine a micro structure design for EAS, the fixing force was measured with various struts diameter and gaps. Experimental result shows that the larger struts diameter and the narrower gaps enhance the fixing force of EAS.

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Replication of skilled polishing technique with serial-parallel mechanism polishing machine

Oba Yuta, Yamada Yuki, Igarashi Keisuke, Katsura Seiichiro, Kakinuma Yasuhiro

Precision Engineering （ELSEVIER SCIENCE INC） 45 292 - 300 2015年10月

研究論文（学術雑誌）, ISSN 0141-6359

Currently, viscoelastic polymers are used to coat automotive body to prevent scratches. On the other hand, the application of a polymer with high viscoelasticity makes the repair polishing process of the coated body more difficult. Hence, performing the polishing process requires the operator to be technically skilled. However, the number of workers with necessary technical skill has been decreasing because of an aging population. In addition, the surface quality and process time are dependent on the proficiency level of the worker. To automate the repair polishing process, in our past research, a serial-parallel mechanism polishing machine was developed to simultaneously control the tool trajectory, tool posture, and polishing force. The present study aims to construct a replication system of a skilled polishing technique on the basis of the above three physical parameters by applying the developed polishing machine. First, the tool trajectory, tool posture, and polishing force of a skilled worker, which reflect the polishing technique, were acquired using a high-speed camera and a dynamometer. By inputting the acquired data to the developed machine, the machine can copy the polishing technique because the tool trajectory, tool posture, and polishing force can be independently controlled. From the results of the polishing test, the surface quality after polishing was comparable to that of the skilled worker output, which satisfies the criteria of surface quality.

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Experimental study of crystal anisotropy based on ultra-precision cylindrical turning of single-crystal calcium fluoride

柿沼康弘

PRECISION ENGINEERING-JOURNAL OF THE INTERNATIONAL SOCIETIES FOR PRECISION ENGINEERING AND NANOTECHNOLOGY （ELSEVIER SCIENCE INC） 40 172 - 181 2015年04月

研究論文（学術雑誌）, 査読有り, ISSN 0141-6359

To realize ultimately efficient signal processing, it is necessary to replace electrical signal processing circuits with optical ones. The optical micro-resonator, which localizes light at a certain spot, is an essential component in optical signal processing. Single-crystal calcium fluoride (CaF2) is the most suitable material for a highly efficient optical micro-resonator. The CaF2 resonator can only be manufactured by ultra-precision machining processes, because its crystal anisotropy does not allow the application of chemical etching. However, the optical micro-resonator's performance depends definitely on the surface integrity.
This study investigated the relationship between surface quality after ultra-precision machining and crystal anisotropy. Firstly, crack initiation was investigated on the (1 0 0), (1 1 0), and (1 1 1) planes using the micro-Vickers hardness test. Secondly, brittle-ductile transition was investigated by orthogonal cutting tests. Finally, cutting performance of cylindrical turning was evaluated, which could be a suitable method for manufacturing the CaF2 resonator. The most difficult point in cylindrical turning of CaF2 is that the crystalline plane and cutting direction vary continuously. In order to manufacture the CaF2 optical micro-resonator more efficiently, analysis was conducted on crack initiation and surface quality of all crystallographic orientations from the perspective of slip system and cleavage. (C) 2014 Elsevier Inc. All rights reserved.

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サーボ情報を応用したびびり振動に対する安定主軸回転数同定

小池綾，柿沼康弘，青山藤詞郎，大西公平

日本機械学会誌 81 （ 830 ） 15-00387 2015年

研究論文（学術雑誌）

Evaluation of subsurface damage caused by ultra-precision turning in fabrication of CaF2 optical micro resonator

柿沼康弘

CIRP ANNALS-MANUFACTURING TECHNOLOGY （ELSEVIER SCIENCE BV） 64 （ 1 ） 117 - 120 2015年

研究論文（学術雑誌）, 査読有り, ISSN 0007-8506

The optical micro-resonator, which stores light at a certain spot, is essential in next-generation optical signal processing. Single-crystal calcium fluoride (CaF2) is the most suitable material for this element. Ultra-precision turning is a feasible fabrication process for CaF2 optical micro-resonators. In this study. the influence of subsurface damage on the resonator's Q factor is investigated. TEM observation shows that the subsurface layer of up to several tens of nanometers thickness changed from single-crystal to polycrystalline morphology due to ultra-precision turning. A diamond tool with 0 degrees rake angle results in lower damage than one with negative rake angle, which enhances the resonator's performance. (C) 2015 CIRP.

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Ultrasonic vibration-assisted machining of chemically strengthened glass with workpiece bending

柿沼康弘

JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING （JAPAN SOC MECHANICAL ENGINEERS） 9 （ 2 ） 2015年

研究論文（学術雑誌）, ISSN 1881-3054

This paper deals with axial ultrasonic vibration-assisted machining with workpiece bending. It was proposed as a novel machining method for the reduction of the chippings at the machined holes during micro through-hole drilling of chemically strengthened glass. In micro through-hole drilling of chemically strengthened glass, machining accuracy and efficiency tend to be low because the material's high hardness and brittleness cause rapid tool wear and large chippings at the inlet and outlet of the machined holes. In order to machine small holes with high accuracy, the reduction of the tensile stress that causes large chippings at the outlet of the machined holes is an issue of primary importance that deserves investigation. In the proposed machining method, the glass plate is bent slightly to be convex upward through the application of a compressive stress at the posterior surface of chemically strengthened glass, with a specially designed jig. Using this proposed method that can reduce the tensile stress, the chipping size at the outlet of the machined holes was successfully reduced with applied compressive stress values of 38.9 MPa. In conclusion, it has been clear that the axial ultrasonic vibration-assisted machining with workpiece bending has the potential for achieving high-precision and high-efficiency machining for chemically strengthened glass.

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柿沼 康弘

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柿沼　康弘

論文 - 柿沼　康弘