International Journal of Automation Technology
Online ISSN : 1883-8022
Print ISSN : 1881-7629
ISSN-L : 1881-7629
11 巻 , 2 号
選択された号の論文の20件中1~20を表示しています
Special Issue on Multiaxis Control and Multitasking Machining
  • Keiichi Nakamoto
    原稿種別: Editorial
    2017 年 11 巻 2 号 p. 139
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    Machine tools using numerical control (NC) devices are typical mechatronics products, and introducing them is a powerful way to automate plant production. NC machine tools in workshops meet the requirements of high accuracy and efficiency in the machining of a variety of parts and mold dies.

    Turning centers and machining centers are typical examples of such machine tools. Various cutting processes have been integrated in them to cope with the increase in machine parts that not only have complicated geometries but also must be made with high accuracy, in small quantities, and in a short machining time. In addition, turning and machining centers have been given multitasking capabilities, and the number of control axes has been increased so that complex products may be manufactured efficiently.

    Given that the strong attention and interest in multiaxis control and multitasking machine tools are rapidly increasing, it is fitting that the current state of the art of these tools and their practical and applicable technologies be presented.

    This special issue features 16 research articles – one review and 15 papers – related to the latest research results and practical case studies in multiaxis control and multitasking machining. Their subjects cover various advances in machine control, motion accuracy evaluation, machining error analysis, chatter vibration monitoring or suppression, trouble-free tool path generation, process planning, and new applications of the machine tools.

    We thank the authors for their contributions to this special issue, and we are sure that both non-specialists and specialists alike will find the information the authors provide both interesting and informative. Moreover, we deeply appreciate the reviewers for their incisive efforts. Without these contributions, this special issue could not have been realized. We truly hope that this special issue will trigger further research on multiaxis control and multitasking machining.

  • Keiichi Nakamoto, Yoshimi Takeuchi
    原稿種別: Review
    2017 年 11 巻 2 号 p. 140-154
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    This paper presents an overview of recent advances in multiaxis control and multitasking machining, the machine tools’ kinematic configurations, and the supporting and cutting technologies used for complex form shaping. The functions of the metal cutting machine tools have been expanded to meet high productivity and high accuracy requirements for machining complicated and difficult parts on a single machine. Among these functions, the increase in the number of controlled axes and the multitasking capability in one chucking process enable machine tools to manufacture complex products efficiently. The historical background and application field of machine tools are discussed, mainly by taking examples from turning- and milling-based machining. Then, research challenges to improve machining results are introduced. This paper also presents examples of the latest cutting technologies and the current status of related supporting technologies.

  • Daniel Spescha, Sascha Weikert, Oliver Zirn, Konrad Wegener
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 155-164
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    This paper presents an effective method for the synchronisation of multiple feed axes with differing controller bandwidths by delaying the set point trajectories of those axes with higher bandwidths.

    First, a simplified model of a cascade-controlled feed axis is defined, which allows the problem to be treated analytically. The problem of synchronisation of the feed axes is then analysed mathematically, leading to the hypothesis of synchronisation through a delay of the set points of the more dynamic axes. Subsequently, the dynamic error behaviour and boundaries of a feed axis are calculated. The optimal damping factor for a feed axis is shown to be 1/\sqrt{{2}} and the dynamic error can be formulated in terms of the bandwidth and acceleration or jerk limit.

    The proposed method is proven through a simulation and verified based on experimental results. In addition, the stated error bounds are verified\rev{,} and the limits of the applicability are determined.

  • Olaf Holowenko, Bernd Kauschinger, Steffen Ihlenfeldt
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 165-170
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    From the economic point of view, rising the output rate of processing machines is a key requirement. Thereby, particular demands are to be met, i.e., product quality, process stability, energy consumption, impact of surroundings, or safety at work. Rising the output rate is limited, if only one of these demands can not longer be met. In this paper, a novel control approach is presented that allows to change the executed motion profile due to the actual output rate. Increasing the machine’s performance is evaluated on experimental results. Unused potentials of servo drives are opened up to generate highly dynamic multi-axis motions in processing machines.

  • Tadahiro Nishiguchi, Shogo Hasegawa, Ryuta Sato, Keiichi Shirase
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 171-178
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    Several methods for evaluating the motion accuracy of the rotary axes in five-axis machining centers have been proposed till date. As it is known that particular motion errors exist around the motion direction changing points, it is important to evaluate the behavior of the rotary axes around these points. However, the influence of the motion error in the translational axes is included in the conventional evaluation results, as the translational axes reverse at the motion direction changing points about the rotary axes. In this study, an evaluation method which can assess the behavior of a rotary axis around motion direction changes by synchronous motion of translational and rotary axes is proposed. In this method, the direction of translational axes does not change when the motion direction of a rotary axis changes. A measurement test and actual cutting tests are carried out to clarify the influence of the behaviors of rotary axes on the motion trajectory and machined surface, caused by the change in the motion direction of the rotary axis. Simulations of the motion are also carried out to discuss the causes of inaccuracy.

  • Soichi Ibaraki, Ibuki Yoshida
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 179-187
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    This paper presents a simulator that graphically presents the influence of rotary-axis geometric errors on the geometry of a finished workpiece. Commercial machining simulation software is employed for application to arbitrary five-axis tool paths. A five-axis kinematic model is implemented with the simulator to calculate the influence of rotary-axis geometric errors. The machining error simulation is demonstrated for 1) the cone frustum machining test described in ISO 10791-7:2015 [1], and 2) the pyramid-shaped machining test proposed by some of the authors in [2]. The influences of the possible geometric errors are simulated in advance. By comparing the measured geometry of the finished workpiece to the simulated profiles, major error causes are identified without numerical fitting to the machine’s kinematic model.

  • Daisuke Kono, Fumiya Sakamoto, Iwao Yamaji
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 188-196
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    A measuring instrument, Linked Ball Bar (LBB), is developed to measure machine tool motion errors quickly, flexibly, and robustly. The LBB employs the concept of double ball bar (DBB) and measures the distance between two balls attached to the spindle and table. The problem of short measurement range, the drawback of the DBB, is solved using a link. The measurement accuracy of the LBB is investigated. The analytical resolution of displacement measurement using the LBB is under 30 nm when the displacement direction coincides with the sensitivity direction. The difference between the LBB and the laser interferometer is less than 1 μm in the center measurement range of 75 mm. The repeatability of the LBB is ±0.4 μm and is at the same level as the interferometer. The kinematic error of a five-axis machine tool is measured using the LBB to demonstrate its validity. The parallelism between the C-axis and Z-axis identified using the LBB agrees with the result measured using the cylindrical square. The difference between the LBB and the cylindrical square is about 10 μm/m at the maximum. The LBB can provide quick and flexible measurements of the motion errors of five-axis machine tools.

  • Yukitoshi Ihara, Kazutaka Tsuji, Toru Tajima
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 197-205
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    The ISO accuracy test standard for five-axis machining centers was revised recently. A cone frustum cutting test by end milling, well-known for testing multi-axis controlled machine tools for aircraft part processing, is adopted in the ISO standard as a similar and precise test. It considers both the accuracy of the finished test piece and an interpolation accuracy test measured by ball bar in the same-feed motion of cone frustum cutting. Although it is possible to apply the ISO test methods to various structures of five-axis machining centers, the application of the cone frustum test to multi-axis machine tools with a rotary axis on the workpiece side is rare; thus, it is difficult to evaluate the test results. In this report, the ISO test method was outlined. Next, the ball bar cone frustum test was performed on a five-axis machining center whose two rotary axes were located on the workpiece side. The evaluation method of the test results is discussed. Moreover, the ball bar cone frustum test was also performed on turn-mill complete machining centers to confirm the effectiveness.

  • Ippei Kono, Takayuki Miyamoto, Koji Utsumi, Kenji Nishikawa, Hideaki O ...
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 206-214
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    This study aims to suppress vibration during the machining of long and thin fin parts. Typically, fin parts have low stiffness because fixing the fin is impeded by a end-mill, machine tool or other fins. In this study, multiple tuned mass dampers (TMDs) with the same characteristics were applied to the machining of a fin part measuring 18 mm × 180 mm × 2600 mm. The characteristics of the TMDs were optimized by calculation using a lumped-mass-points system model of the fin part. Then, an impact hammer test and a machining test were conducted on the actual fin part. The dynamic stiffness of the fin part was improved by up to 14 times by using five TMDs, and the amplitude of vibration during machining was decreased by more than 90%.

  • Yuki Yamada, Takashi Kadota, Shinya Sakata, Junji Tachibana, Kenichi N ...
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 215-225
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    Parallel turning technology is considerably important in future multi-tasking machine tool because it has the potential to enhance the stability limits, compared to turning operations using a single tool. Although stability prediction models for parallel turning have been developed recently, the technique of in-process monitoring of chatter is almost out of focus. In this study, the monitoring of chatter based on the sensorless cutting force/torque technique was evaluated in the parallel turning and cutting of the same surface of an elongated workpiece. Two cutting force/torque estimation methods were evaluated: a conventional disturbance observer (DOB) using internal information from a servomotor and a multi-encoder-based disturbance observer (MEDOB) using load-side position/angular information as well. In the DOB-based monitoring, chatter frequency components were observable regardless of the guideway type and drive system. However, chatter monitoring may be difficult when the angle of the servomotor is changed slightly because of the damping properties of the sliding guideway. In the MEDOB-based monitoring, the waveform of the estimated cutting force reflected the vibrational state at the cutting point well, and the extraction of chatter frequency components became easier regardless of the guideway type.

  • Kohei Ichikawa, Jun’ichi Kaneko, Masanobu Hasegawa, Takayuki Iwasaki, ...
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 226-234
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    Simultaneous 5-axis control machining is used to machine components in complex, deep grooved shapes. In order to maintain actual feed rates in this kind of machining, it is vitally important to secure continuity in the movement of the rotational axis. When the tool reverses its direction of travel, however, its axis of rotation is liable to make sudden movements. In this study, therefore, we first derive candidate tool postures that can meet the conditions for relative postures to machined surfaces while avoiding tool interferences. We then develop a method for automatically planning continuous changes in the command values of the rotating axial angles in the machine coordinate space.

  • Kento Watanabe, Jun’ichi Kaneko, Kenichiro Horio
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 235-241
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    This study developed an automatic planning method for tool collision avoidance, with posture adapted to the uncut shape of a workpiece to avoid collisions between the tool and workpiece in five-axis machining. This method sequentially judges the likelihood of collision between the holder and shank parts of the tool and the workpiece while machining, which is updated with tool motion. Then it automatically determines tool postures in which no collisions occur. The process of setting the search range for collision avoidance postures of the tool when collisions occur is made more efficient; it is possible to prevent rapid changes in tool posture at the time of avoidance, while reducing the time for geometric operations necessary when searching for compatible orientations.

  • Kenta Koremura, Yuki Inoue, Keiichi Nakamoto
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 242-250
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    In the manufacturing industry, there is an urgent need to shorten the manufacturing lead time of products. Therefore, optimizing process planning is essential to realize high efficiency machining. In this study, in order to develop a computer aided process planning (CAPP) system using previously proposed machining features, a prediction method for some process evaluation indices is proposed. Many candidates for the machining process exist, depending on the recognized machining features in a previous study. Therefore, by using these indices, operators can select a suitable process from among these candidates according to their ideas. Case studies of process planning are conducted to confirm that the operator’s strategy affects the selection of the machining process candidates. From the case study results, it is found that the proposed process evaluation indices have potential use in determining the machining process utilized, and are suitable for a flexible CAPP system of multi-tasking machine tools.

  • Naoya Shimada, Noboru Nagashima, Keiichi Nakamoto
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 251-257
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    Multi-tasking machine tools are popular owing to properties such as high flexibility and productivity. It is essential for an operator to avoid collisions between the machine structure and workpieces as machine tools realize complicated motions. Thus, a machine simulator is widely used prior to machining operations to solve this problem. However, unexpected collisions often occur in a commercial machine simulator when the setup of a workpiece or a jig differs from the 3D models created in advance. Therefore, this study proposes a machine simulator that utilizes 3D models created by measuring the shape and position of the workpiece and jig on the machine tool. In a case in which the workpiece differs from the desired workpiece, it is necessary to determine a suitable position and orientation of the target shape based on the obtained objects to modify NC (Numerical Control) programs. In this study, a decision method of the position and orientation of target shape is devised such that it corresponds to actual objects obtained by on-machine measurement.

  • Toru Kizaki, Yusuke Ito, Naohiko Sugita, Mamoru Mitsuishi
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 258-269
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is a promising material for dental restoratives. Although grinding or polishing with diamond tools is widely used to machine Y-TZP, the processing efficiency and cost of the process are problematic. In this study, we applied laser-assisted machining (LAM) to Y-TZP, in which non-diamond tools were used. Unlike LAM applied to other materials, decrease of the fracture toughness at elevated temperatures which is a unique feature of the Y-TZP was adopted as a key mechanism for machinability enhancement. In addition, a systematic method to determine the LAM conditions was proposed. In this study, we explain the LAM condition-determining method, which is based on numerical simulations of the temperature distribution. Secondly, the determining method was evaluated through a series of LAM experiments to obtain the appropriate LAM conditions. Using the determined conditions, LAM of Y-TZP was demonstrated to be effective; the thrust force was reduced by 51.3% and the tool wear was significantly reduced, while no cracks formed on the Y-TZP.

  • Naoki Asakawa, Ryota Kito, Keigo Takasugi
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 270-277
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    In spite of the importance of the globe as an educational and cultural tool, for visually impaired users, common globes are just spherical objects. Although there are commercially available globes for visually impaired users, globes that have convex and concave features on the surface denoting coastlines and country borders, most of them are expensive because they are made by hand. Consequently, visually impaired users wishing to purchase globes have a very limited range of choices. In terms of industrial production, producing globes with convex and concave surfaces essentially involves machining a spherical surface. For instance, with common machine tools, even positioning or marking a spherical surface of a certain size is very difficult operation since the posture of the tool must change dramatically. The purpose of the study is to develop a CAM system to design the surface of tactile globes suitable for individual needs and to manufacture them for the visually impaired at low cost and with a short lead time. In the report, as the first step, a method of holding the sphere and marking it via 3D-CAD/CAM technology and the control technology of an industrial robot is proposed. As a result, the system enables the marking of the coastlines and country borders on spheres automatically using our own CAM system and an industrial robot.

  • Kyosuke Kawagishi, Shoma Umetani, Ken Tanaka, Eiji Ametani, Yoshitaka ...
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 278-286
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    A new four-axis 3D printer using fused-deposition modeling (FDM) technology has been developed. The hardware components, consisting of a mechanical structure and servo-control system, and an original computer-aided machining (CAM) system were developed. Three-dimensional printers, particularly those using FDM technology, have gained popularity even in hobby use for the easy modeling of special and original parts. Three-axis control systems using stepping motors or servomotors are generally used for the development of conventional 3D printers. The nozzle portion is therefore constrained in one direction. This leads to limitations in modeling 3D shapes. Adding degrees of freedom is necessary to create more complex features. We designed a new 3D printer with multi-axis control to address this problem. Our final goal is the development of a five-axis 3D printer. We started with a four-Axis 3D printer as a first step. The number of lamination directions is increased from three to four. As conventional CAM systems cannot be used to program the desired lamination for a four-axis 3D printer, a new CAM system using the Kodatuno kernel was developed. The system can determine the nozzle orientation based on the machine tool formulation. This paper reports the developmental background and an overview of the developed machine tool as well as its characteristics, its evaluation results, and our future plans.

Regular Papers
  • Yoshinobu Ueno, Jing Zhang, Kazuhiro Aoyama
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 287-300
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    A supply chain (SC) is an organization in which multiple companies cooperate in supply functions, e.g., moving information or materials. Previous studies of SC designing and planning are categorized by their planning time periods into three categories, e.g., strategic, tactical, and operational. Top-down design of an SC, where design decisions are made in the sequence of strategic, tactical, and operational, is rational because of preventing rework of design work. But as few models supports strategic decision making quantitatively, top-down design of an SC has not been realized. In the present study, a method of quantitatively expressing SC’s capabilities of flowing information and materials and simulating its performance is developed. The method is then implemented with a system dynamic model to evaluate, qualitatively and quantitatively, the effectiveness of the model.

  • Akira Chiba, Souta Matsusaka, Hirofumi Hidai, Noboru Morita
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 301-310
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    Numerical analysis revealed the thermal behavior during the laser joining of two glass plates using a low melting point glass frit as an adhesive. The proposed model is a structure consisting of a straight line glass frit sandwiched between glass plates. The numerical solutions of three associated heat equations were provided by the finite difference method. The constant heat flux model predicted the temperature at the contact interface between the glass frit pattern and the glass plate. The influence of heat source shape on temperature distribution was compared using circular and elliptical beams. Irradiation with the elliptical beam extended the softening domain of the glass frit pattern further than the circular beam. The increase in softening domain depended on the major diameter of the elliptical beam. Thermal diffusion had no influence on the glass plate domains at distances greater than 1 mm from the edge of the glass frit pattern. Laser frit sealing is an effective means of resolving the issue of heat influence on electronic devices.

  • Francesco Aggogeri, Andrea Avanzini, Alberto Borboni, Stefano Pandini
    原稿種別: Paper
    2017 年 11 巻 2 号 p. 311-321
    発行日: 2017/03/05
    公開日: 2018/11/05
    ジャーナル オープンアクセス

    This paper proposes a robot gripper in polymeric material for solid micro-meso parts. The gripper is developed using a light-weight, highly deformable and low cost material, that allows elastic deformations. The proposed solution consists of a simple geometry, incorporating the complexity of the mechanical transmission in the non-linear high deformations of the flexible elements of the device. This choice permits to grip multi-sizes objects. The design approach focuses on Ludwick material model, that describes deformable materials with a nonlinear elastic behavior. The kinematics of the gripper is presented and the results are verified with the finite element analysis. Finally, the gripper was fabricated and validated through a set of experimetal tests. The obtained resulsts confirmed the theoretical and simultion models. The maximum opening and force of the gripping jaws are 1,500 μm and 155 mN, repsectively. Nevetheless further performances may be obtained using different geometrical choices developed in the kinematic analysis.

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