Details of a Researcher - Kakinuma, Yasuhiro

Papers - Kakinuma, Yasuhiro

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Study on Cutting Force and Tool Wear in Machining of Die Materials with Textured PCD Tools Under Ultrasonic Elliptical Vibration

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

International Journal of Precision Engineering and Manufacturing - Green Technology 10 ( 1 ) 35 - 44 2023.01

ISSN 22886206

Machining of steel-based alloy (STAVAX) and tungsten carbide (WC) is very challenging due to their superior hardness. Severe wear in the machining of the die materials is the dominant problem. Texturing on the rake face of the tool and ultrasonic elliptical vibration cutting (UEVC) may resolve this issue and could prolong tool life. The patterns on the rake face of the tool entrap the chip and debris created in machining and prevent abrasion. During UEVC the flank face of the tool does not contact the workpiece and the rake face of the tool helps the chip evacuate from the machining area when the tool disengages with the workpiece. Thus, UEVC reduces cutting force and tool wear compared to conventional cutting. This paper investigates the cutting performance and tool wear in machining of the die materials with textured polycrystalline diamond (PCD) tools under UEVC. The linear patterns parallel or perpendicular to the chip flow are engraved on the rake face of the PCD tools with the focus ion beam (FIB) process. Orthogonal cutting experiments are carried out on ultra-precision machine tools with and without UEVC. Machining under UEVC remarkably reduces the cutting and thrust force and improves tool life. For machining of STAVAX with the textured PCD tool, the linear patterns alone do not improve the cutting, but they improve the cutting when they are combined with UEVC. In machining of WC, the linear pattern becomes effective by slightly decreasing the thrust force and friction coefficient when UEVC is not applied.

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Slurry Conditions for Reaction-Induced Slurry-Assisted Grinding of Optical Glass Lens

Kawasato Tappei, Takamaru Hinata, Hamazono Kazuhisa, Fukuta Masahiko, Tanaka Katsutoshi, Chiba Yusuke, Nagano Mikinori, Kato Hidebumi, Kakinuma Yasuhiro

International Journal of Automation Technology (Fuji Technology Press Ltd.) 17 ( 1 ) 40 - 46 2023.01

ISSN 18817629

The demand for optical glass lenses is rising owing to the increase in image resolution. Optical glass is a hard and brittle material. Thus, an efficient and precise grinding method is required for optical glass to improve lens quality and productivity. There are a few methods of producing crack-free machined surfaces; however, they provide only limited grinding efficiency. To resolve this issue, the authors’ group has proposed the reaction-induced slurry-assisted (RISA) grinding method, which expands the range of ductile-regime grinding by utilizing the chemical–mechanical action of a cerium oxide slurry. In this study, the grinding performance of RISA grinding is experimentally evaluated for different pH levels. The results are compared using Tukey’s test, where surface roughness is considered as the characteristic value and the pH value as the analyzed factor. The result shows that RISA grinding efficiently produces a high-quality surface when the slurry is alkaline. The adhesion of cerium oxide abrasives to the wheel in RISA grinding follows the same mechanism as slurry aggregation. In addition, adhesion is more likely to occur when the alkalization of the slurry promotes aggregation. The tank in the slurry supply unit is replaced with a rotating tank to ensure stable RISA grinding with a highly aggregable slurry while preventing aggregation. The performance evaluation shows that a high-quality surface with a surface roughness of less than 10 nm in most parts is obtained. Moreover, the critical depth of cut stably increases by a factor of 5.8.

Evaluation of fabrication parameters for foam stainless steel in directed energy deposition

IKEDA Yushi, TAKEUCHI Toshihiro, KOIKE Ryo, KAKINUMA Yasuhiro, KONDO Masaki, ODA Yohei, MORI Takanori

Journal of Advanced Mechanical Design, Systems, and Manufacturing (The Japan Society of Mechanical Engineers) 17 ( 1 ) JAMDSM0011 - JAMDSM0011 2023

ISSN 1881-3054

Directed energy deposition (DED), a metal additive manufacturing process, has attracted considerable attention in various industries. In the past few decades, several studies have been conducted to enhance the quality of DED-produced parts. Various studies on powder- and laser-based DED have focused on eliminating the residual pores in the fabricated parts, which decrease the mechanical strength. In contrast, this study aims at intentionally increasing the residual pores to produce a porous structure in metals called as foam metal, which realizes lightweight and excellent energy absorption properties. Despite being well-known for their attractive properties, Foam metals are rarely used due to the technical difficulties in their production, which requires special devices and entails considerable cost. The simplicity of the DED process makes it a promising approach to fabricate foam metals because it is easy to foam at the fabrication point by mixing a foaming agent, such as titanium hydride (TiH2), into the material powder. This study evaluates the DED foaming process in stainless steel alloys by changing the particle size of the TiH2 powder and the scanning path to obtain the optimal conditions for enhancing the pore dispersion. The experimental results show that, when the particle size of the foaming agent is small, the number of pores and their distribution increases. Additionally, the mechanical properties are also evaluated through compression experiments, and the energy absorption ratio is found to be higher when a smaller foaming agent is used.

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

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

Journal of Advanced Mechanical Design, Systems and Manufacturing 17 ( 1 ) 2023

Selective laser melting (SLM) is one of the additive manufacturing (AM) methods which is applicable to metal. This technique makes it possible to form complex internal shapes such as lattice structures. The lattice structure is expected to have weight reduction and vibration suppression effects on the product. In addition, a support structure is essential for the SLM fabrication process, which has the role of supporting the product and dissipating heat from the product. However, steep temperature gradients due to local laser irradiation and non-uniform heat conduction during the process can cause bending and cracking of the product. In particular, the support structure and lattice structure consisting of thin metal struts are greatly affected by process conditions, so it is necessary to select conditions suitable for stable and high-precision modeling. 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 the volumetric energy density was confirmed, and suitable laser conditions were examined. In the compression test of the lattice structure, it was clear that the amount of energy absorption changed depending on the laser power, and the condition of 240 W achieved the maximum energy absorption.

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Process Monitoring for Machine Tools

KAKINUMA Yasuhiro

Journal of the Japan Society for Precision Engineering (The Japan Society for Precision Engineering) 89 ( 12 ) 866 - 870 2023

ISSN 09120289

A machine learning approach for simulation of multi-stage laser forming process

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

JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING 17 ( 1 ) 2023

ISSN 1881-3054

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Enhancing the multi-encoder-based cutting force estimation along the stationary axis of a machine tool with multiple inertia dynamics

Yamamoto K., Kamba A., Takeuchi K., Fujita J., Fujimagari Y., Kakinuma Y.

International Journal of Advanced Manufacturing Technology 123 ( 3-4 ) 1215 - 1229 2022.11

ISSN 02683768

Wideband cutting force sensing is a key technology for process monitoring. Sensorless cutting force estimation using the internal servo information of a machine tool with ball-screw-driven stages has been studied owing to its high maintainability and ease of introduction. In the motor current-based method, the cutting force estimation along the stationary axis is challenging, and the estimation bandwidth is significantly limited owing to the low sensitivity of the motor current in the high-frequency range. The dual-inertia model-based load-side disturbance observer (LDOB) can estimate the cutting force along the stationary axis using the relative position obtained from the rotary and linear encoder. The linear encoder is installed relatively near the cutting point and has a high sensitivity in the high-frequency range. However, this approach is not applicable to machine tools with complicated structural dynamics. To address this challenge, we propose a cutting force estimation method along the stationary axis using the Kalman filter (KF) based on a multiple inertia model derived solely from the relative position signal. The dynamics, depending on the stage position of the feed drive, were modeled using linear interpolation. Through end milling tests, we confirmed that the cutting force estimation accuracy along the stationary axis of a machine tool with multiple inertia dynamics was significantly improved by the proposed method compared to the current and LDOB-based methods. Additionally, the wideband cutting force could be estimated using the proposed method for bandwidths up to 1000 Hz.

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BASIC STUDY ON GEAR COATING TECHNOLOGY USING DIRECTED ENERGY DEPOSITION

Ikeda Yuriko, Okochi Wataru, Maki Teppei, Takaki Kazuhiro, Shiwaku Noriyuki, Mori Takanori, Hirono Yoko, Koike Ryo, Kakinuma Yasuhiro

Proceedings of the International Symposium on Flexible Automation (The Institute of Systems, Control and Information Engineers) 2022 ( 0 ) 141 - 143 2022.07

In recent years, with the spread of electric vehicles, development of high-performance mechanical parts has been required. With respect to the manufacturing process, metal Additive Manufacturing (AM) such as Directed Energy Deposition (DED) is attracting attention in automobile industry. Since the DED process can deposit molten material onto the specific surface, where it solidified, it is regarded as a promising coating process to enhance the hardness and surface functionality of mechanical parts. From this perspective, a gear coating process using DED is proposed in this research to strengthen gear surface and its basic study is conducted. Concretely, the coated material quality and mechanical properties like hardness are evaluated.

ENHANCEMENT OF MAGNETIC PROPERTIES AND CRYSTAL STRUCTURE OF SOFT MAGNETIC MATERIALS FABRICATED BY DIRECTED ENERGY DEPOSITION

Kanemaru Soma, Koike Ryo, Kakinuma Yasuhiro, Hirono Yoko, Mori Takanori

Proceedings of the International Symposium on Flexible Automation (The Institute of Systems, Control and Information Engineers) 2022 ( 0 ) 131 - 134 2022.07

Additive manufacturing (AM) allows objects to be designed and formed directly from three-dimensional data. Directed energy deposition (DED), an AM method, can produce near net shape parts, which can reduce lead time and material waste, resulting in lower costs. From the growing interest in vehicle electrification, usage of AM technology for functional materials such as soft magnetic materials has been attracting attention. Performance indicators of soft magnetic materials are high saturation polarization, high susceptibility, and low coercivity. These properties depend on microstructure and crystal texture. In this research, experiments were carried out to find ideal process parameters of DED using two soft magnetic materials, FeSi and FeCoV. Crystal orientation of both materials showed anisotropic properties with columnar grains in the build direction. Six process parameters, laser power, feed rate of nozzle head, dwell time, rotational speed of disc in powder pod, powder supply rate, and carrier gas speed were adjusted to perform a screening test. It was found that dwell time and powder supply rate have a large influence on the shape of deposit. Also, higher deposit density is achieved by higher laser power and lower feed rate. Consequently, optimal process parameters of both FeSi and FeCoV deposits were obtained.

Dynamical characteristic validation of motorized CFRP spindle unit based on receptance coupling

Kato M, Kono D, Kakinuma Y

Mechanical Systems and Signal Processing 173 2022.07

ISSN 08883270

Carbon fiber reinforced plastic (CFRP) is used in machine tool components to provide high specific stiffness with high damping properties and low thermal expansion; further, it is combined with metals in specific ratios to enable the use of existing equipment and machine design. The development of CFRP spindle shafts has design flexibility in the stacking sequence. The improvement and analysis of spindle unit dynamics are essential for achieving high productivity in machining, and prediction methods for dynamic stiffness with lower computational costs are required to estimate and optimize the machine performance of the design proposals. Therefore, parameter identification for the equivalent physical properties of composite materials with CFRP and steel was proposed in this paper to use general solutions for a one-dimensional Timoshenko beam model. Four different analytical models of the CFRP spindle shaft following the actual development phase were designed via generalized receptance coupling to multi points in order to observe the model shapes. The frequency response functions and mode shapes of the spindle shaft models were compared with those of finite element methods and impact tests. The spindle shaft model reflecting the applicable location of CFRP in the rotational axis demonstrates a sufficient estimation accuracy for natural frequencies and mode shapes. The spindle shaft model reflecting the stacking sequence demonstrates robustness against the parameterization errors of the CFRP. A motorized CFRP spindle unit was modeled by combining a spindle shaft model and bearing models; the bearing dynamics were experimentally studied under heat radiation after stopping the spindle rotation. Moreover, a steel spindle shaft model and several types of CFRP layout with the same dimensions were compared on the spindle unit model; the CFRP spindle unit yielded a greater dynamic stiffness. The layout of the CFRP application and requirements on manufacturing are discussed for the further improvement of the dynamic stiffness.

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Experimental Confirmation of a Controllable Transmission/Braking Element Consisting of a Functional Elastomer Pasted on a Winding Surface

Koyanagi K., Kakinuma Y., Anzai H., Sakurai K., Oshima T.

Actuators 11 ( 4 ) 2022.04

Electoadhesive (EA) gel can be applied to various mechatronics devices because it provides more degrees of freedom in mechanical design than other functional materials. While case studies have revealed much about these devices, the knowledge attained is still not integrated. We assembled new structured and controllable transmission and braking elements by fixing EA gel on plain and/or winding surfaces. This paper summarizes the characteristics of these devices from experimental findings on the initial pressure on the EA gel surface. The results showed that it is important for the initial pressure to be stable at approximately 0.5–1 kPa.

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超硬合金の楕円振動切削における逃げ面テクスチャ工具の開発

Ito Hiroaki, Kobayashi Yutaka, Shimada Hiroyuki, Yamada Hiroki, Kakinuma Yasuhiro

Proceedings of JSPE Semestrial Meeting (The Japan Society for Precision Engineering) 2022S ( 0 ) 383 - 384 2022.03

超硬合金の金型を製造するための切削加工技術が求められている．超硬合金の切削では，粉末状の微細な切りくずが工具と工作物の界面に入り込み工具摩耗を促進する．そこで，本研究では，切りくず排出性を向上させるために，工具逃げ面に微細溝テクスチャを施した切削工具を提案し，これを用いて超硬合金の楕円振動切削試験を行った．テクスチャ形状と切りくず排出性の関係を実験的に調べ，提案工具の耐摩耗性を評価した．

Robot polishing control with an active end effector based on macro-micro mechanism and the extended Preston's law

Kakinuma Y., Ogawa S., Koto K.

CIRP Annals 71 ( 1 ) 341 - 344 2022.01

ISSN 00078506

There is a strong demand for automating the rough polishing process in plastic-mold manufacturing. In this study, with the active end effector being capable of fast force control and dynamic spindle control, a robot polishing control system based on a macro-micro-mechanism was built, which controls all parameters related to Preston's law and can be linked with computer-aided manufacturing. Based on the extended Preston equation, a polishing control algorithm that achieves uniform surface quality and uniform removal depth was proposed. The spherical rough polishing test on carbon steel demonstrated the efficacy of the proposed robot polishing control.

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Theoretical approach on the critical depth of cut of single crystal MgF<inf>2</inf> and application to a microcavity

Hayama Y., Fujii S., Tanabe T., Kakinuma Y.

Precision Engineering (ELSEVIER SCIENCE INC) 73 234 - 243 2022.01

ISSN 01416359

Optical microcavity, which can localize light at a certain spot for a short period of time, has a wide range of applications, such as optical signal processing and optical frequency combs. Single crystal CaF2 has excellent optical properties and many research on the manufacturing process to create a microcavity has been done. However, due to its unstable thermal conditions, stable oscillation of Kerr comb could not be done. Single crystal MgF2, which also has excellent optical properties, has stable thermal conditions suitable to create a microcavity. Like CaF2, MgF2 microcavity can only be manufactured by ultra-precision cylindrical turning, yet its appropriate processing conditions is not known. In this study, a method to derive the critical depth of cut theoretically in ductile mode machining was proposed in consideration of specific cutting energy, mechanical properties and slip system of workpiece, and tool geometry. The critical depth of cut calculated by the proposed method roughly agreed with the experimental value on the MgF2 plane. Unlike CaF2, MgF2 has an optical anisotropy; therefore, in order to create a microcavity where the refractive angle is constant, the resonance part needs to be made on a cylinder with (001) plane as end face. Therefore, a microcavity was fabricated according to the critical depth of cut on a cylinder with (001) as end face derived from the proposed method, and the surface integrity was evaluated from the viewpoint of microcavity performance.

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Application of RISA grinding method to multiple optical glasses

Takamaru H., Kawasato T., Watanabe K., Fukuta M., Tanaka K., Chiba Y., Kato H., Nagano M., Kakinuma Y.

Procedia CIRP 108 ( C ) 454 - 458 2022

ISSN 22128271

A more efficient and precise grinding method for optical glasses is demanded to improve lens quality and productivity. The Reaction Induced Slurry Assisted (RISA) grinding method enhances the ability of ductile regime grinding by utilizing the chemical mechanical action of cerium oxide slurry. In this study, the grinding performance of RISA grinding to multiple optical glasses is experimentally evaluated. The result shows that RISA grinding efficiently produces a fine quality surface of crown glass with high Si-O bond content.

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Development of temperature analysis environment for Cyber-Physical Systems on IoT platform: a study of dynamical properties under temperature change in machine tool spindle unit using carbon fiber reinforced plastics

Kato M., Kizaki T., Uwano T., Iijima K., Kakinuma Y.

Procedia CIRP 107 1485 - 1490 2022

ISSN 22128271

Industrial networks with a database for collecting and analyzing machine information and process data are key components in production systems in Industry 4.0. In proposed IoT system, more than 300 temperature sensors were externally mounted on a carbon fiber reinforced plastics structured machine tool, and their information was collected through an OPC UA server. Based on impact tests, the spindle nose temperature was found to be correlated to the variation in compliance and resonant frequency. The carbon fiber reinforced plastics structured spindle shaft conducted heat quickly and induced a temperature increase after stopping spindle rotation. The IoT system of a temperature-analysis environment can contribute to experimental analysis and model construction for intelligent technologies.

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Electrical Resistance Characteristics of Electro-adhesive Gel Sheet While Fixing Conductor Object

NISHIMURA Ryo, HIOKI Yuka, ANZAI Hidenobu, SAKURAI Kouzi, NAGATSUMA Akemi, AOYAMA Tojiro, KAKINUMA Yasuhiro

Journal of the Japan Society for Precision Engineering (The Japan Society for Precision Engineering) 88 ( 1 ) 117 - 123 2022

ISSN 09120289

In this study, Electro-Adhesive Gel Sheet (EAGS) was fabricated. It is suggested that the electrical resistance characteristics of EAGS could be applied as slip detection sensors or contact detection sensors. EAG is a functional elastomer which can change surface adhesiveness depending on an electric field, and EAGS is a sheet of EAG fabricated on a flexible electrode sheet. It was found that slipping on the surface when grasping an object or contact with a grounded conductor changes the resistance inside the EAGS, and the mechanism was analyzed from an engineering point of view.

Large force actuator using an electro-adhesive gel super multi-disk

Koyanagi K., Takata Y., Kakinuma Y., Anzai H., Sakurai K., Oshima T.

Advanced Robotics 36 ( 19 ) 983 - 994 2022

ISSN 01691864

Actuators with clutch mechanisms have advantages in safety, backdriveability, and controllability for human-coexistence robots. This paper presents a large force actuator using electro-adhesive gels, which are functional materials controlled by the magnitude of an electric field. The developed actuator can generate and continuously control a force over 560 N and resist with a small force when de-energized. The number of electro-adhesive gel disks is drastically increased to increase the generative force. This paper reports the structural plan for the new actuator and experiments to investigate its basic characteristics. Based on the experimental results, an actuator model is identified for the future design of its control system. This paper contributes to the development of a clutch-type linear actuator with a large generative force, maintaining safety and a high force-to-weight ratio. It also addresses the problem of high-voltage power supply costs for electro-rheological and electro-adhesive materials.

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Shape error analysis in ultra-precision grinding of optical glass by using motor-current-based grinding force monitoring

Iinuma N., Chen B., Kawasato T., Kakinuma Y.

Proceedings of ASME 2022 17th International Manufacturing Science and Engineering Conference, MSEC 2022 2 2022

4K and 8K technologies are attracting attention in optical industries. The most important mechanical element to enhance the imaging performance is the aspherical lens requiring higher surface quality and higher form accuracy. Currently, the production process of optical lenses consists of brittle-mode grinding and pro-longed polishing process, which play a role of shaping the form and producing the fine surface, respectively. However, this process is not considered to be suitable for manufacturing such higher-quality lenses for 4K and 8K imaging devices because a required form accuracy could not be ensured, and the polishing time gets longer. To enhance the form accuracy and production efficiency, application of ductile-mode grinding is expected to reduce polishing amount. However, the shape error generated by the ductile mode grinding is not clear. Therefore, the purpose of this research is to analyze the relation between the shape error and the grinding force estimated from motor-current in the grinding machine. The motor-current acquisition system in all translational axes and the work spindle is constructed and implemented into a 4-Axis ultraprecision aspherical machine. The grinding force in each axis is derived by subtracting the motor current during non-grinding previously obtained in air-grinding test from the current during grinding. Firstly, the behavior of the motor current in each axis is investigated from the viewpoint of repeatability and position dependency. While the periodic fluctuation of the motor current affected by the influence of permanent magnet in the linear motor is confirmed, it shows high repeatability at each position. This result indicated that grinding force is easily calculated from the motor current with less uncertainty. Then, influence of grinding condition in the range of ductile mode grinding on the shape error is analyzed by monitoring the motor current. Toward the outside of the workpiece, the shape error gradually increases with the increase of motor current, which means larger grinding force at the outer side causes the deformation of the resin grinding wheel.

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Optimization of process parameters for hardness in high speed coating by Directed Energy Deposition

Satoh T., Koike R., Kakinuma Y., Hirono Y., Mori T., Oda Y.

Procedia CIRP 111 214 - 217 2022

ISSN 22128271

In recent years, metal 3D printers have been attracting attention not only for building solid parts but also for repairing and coating processes. The goal of this study is to apply the directed energy deposition (DED), which is one of the additive manufacturing, to realize high-quality metal coating by depositing the coating material on a cylindrical object. To evaluate the effect of process parameters, experimental points were set up based on the central composite design and deposition was performed using Inconel 625 as the material powder. The hardness of the coating was measured and statistically analyzed by the response surface methodology. From the analysis results, it was found that laser power has the largest influence on the coating hardness, which was improved by 28% compared to the low rotation speed by depositing under the optimum processing parameters.

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