Vol.5 No.3 2012

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Research paper : Spinning process using robot technology (H. Arai)−155−Synthesiology - English edition Vol.5 No.3 (2012) by machines, and it is meaningless to simply transfer human skills to a robot. Since the added value of a product obtained by skills is important rather than the skills themselves, the benefit of the machine should be explored rather than trying to copy human skills.Since humans use machines on site, new skills required to master new technologies are born. In force-controlled spinning, the pressing force to be set is ultimately decided by the human personnel on site. Skill learning in manufacturing always includes a creative process.Metal spinning started from making pots and pans, and the advanced skills required to create complex and precise products did not exist from the beginning. Even if muscles and hands are replaced by mechanical devices, the replicated skills are fixed ones. Human beings, who learn by trial-and-error and improve their skills on site, are still necessary. Therefore, rather than aiming to replace skilled workers, we aimed to develop a machine that would be an advanced tool and become effective only when utilized by a person.4.4 Concentration on noncircular shape formationOn the other hand, the machine described in 4.1 was successful in forming noncircular shapes by the application of force-controlled spinning, and this became the selling point of the outcome of this research from then on. At that time, regular exchanges with companies started through the Collaboration Promotion Division. While we presented AIST’s potential at meetings in which several companies in metal-spinning-related fields participated, the development target was narrowed down by listening to the companies’ demands. Daitoh Spinning, a spinning machine manufacturer, participated in these meetings, and expressed their desire to carry out joint research as they became strongly interested in the forming of noncircular shapes. On the basis of this proposal, we obtained a joint research fund from the Small and Medium Enterprise Agency, and thus the prototype of the synchronized spinning machine was fabricated (Fig. 6).In noncircular shape forming by force-controlled spinning, the important issue was shortening the spinning time. At that time, the author happened to visit the International Robot Exhibition and saw linear motors there. This generated the idea of using them in the spinning machine. In this study, effort was placed on patent application rather than academic publication. As a result of the patent application for the spinning machine using linear motors, we obtained funding for strengthening the patent from the Intellectual Property Division and were able to build the prototype of the linear motor machine (Fig. 4).4.5 For the diffusion of the working machineAfter repeated trial runs and metal spinning demonstrations at exhibitions, we received a request for intellectual property licensing from Daitoh Spinning. Joint development of the prototype of the practical machine was conducted through the patent-related funding (Fig. 7). Meanwhile, the author moved to the Advanced Manufacturing Research Institute in 2009, and shifted his research from pioneering robot applications to actual processing technology. Daitoh Spinning started taking orders for the spinning machines that could handle noncircular shapes, but orders slowed down owing to the economic uncertainty after the Lehman Shock, and the company is now seeking ways to improve the situation.4.6 Research and development that does not depend on a scenarioLooking back at the progress of research, it can be seen that there was no consistent scenario and that the research goal changed greatly owing to external and coincidental factors. As part of the positive external factors such as obtaining funding, exchange with companies, and participation in exhibitions, there were many instances where we were encouraged by the Collaboration Promotion Division and the Intellectual Property Division of AIST, and the roles played by such research-supporting sections in advancing the research were significant. Also in this research, the fact that the laboratories for the robotics and manufacturing fields were at neighboring locations, a legacy from the Agency of Industrial Science and Technology, worked positively, and this was particularly useful in gaining knowledge of the metal forming field.5 Characteristic research activities5.1 Synthesis by bricolage – bottom-up integration of elemental technologiesThe construction of the experimental spinning machine described in the beginning of the previous section was typical bricolage, and bricolage at various levels was used in several parts of the research. Most elemental technologies can be organized as a hierarchical structure, and a function to be realized as seen from below becomes an elemental technology when seen from above. For example, we had the force control and position control technologies available as elemental technologies at the beginning of the research. These were combined to realize force-controlled spinning and synchronized spinning as functions of the spinning machine. In the next stage, these were combined as elemental technologies to conduct sheet and pipe spinning in actual parts. By building up the technologies from below, we filled our toolbox with an inventory of technologies (Fig. 10). The control laws that were the basic elements were derived from research done in the robotics field. For example, the impedance control used in the force-controlled spinning was modified from the control law used in a cooperative task between humans and robots.[19]

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