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INTRODUCTION. SPECIAL ISSUE ON RECENT DEVELOPMENTS OF THE TECHNOLOGY OF PLASTICITY IN JAPAN
I WOULD like to thank the Editors who have planned this Special Issue, and say that I am honoured to be able to introduce it. I believe that it will be of value in enumerating Japan's many recent developments in the technology of plasticity, for colleagues not only in Great Britain, but also world wide.
First I would like to review the reasons for Japan's achievements in the technology of plasticity.
The growth of mass production technology in Japan was necessary following World War II in order to revive a country of few resources from economic ruin. Plastic working which is of high productivity is obviously central to the methods for mass production. Needless to say, problems of plastic working are approached mainly by metallurgical and mechanic~tl means. Following the war, however, there was a deep rift between the metallurgical ~md the mechanical engineering fields which was hard to rectify. One of the reasons w~ts that the metallurgists and mechanical engineers in Japan were working separately in different societies.
The Japan Society for Technology of Plasticity, which was born as a research group in 1951, was formally established in 1961 by people associated with the technology of plasticity, regardless of their academic disciplines. The Society has subsequently provided many occasions for interaction and cooperation between metallurgists and mechanical engineers, also very close cooperation among universities, governmental research institutes and industries. The cooperation between researchers and engineers has served further to imFrove conventional techniques from the scientific point of view, as well as to develop new techniques. Developments in the technology of plasticity in Japan could not have been expected without this society, unique in the world.
The Japan Society for Technology of Plasticity now holds national conferences every spring and amumn under the co-sponsorship of the Japan Society of Mechanical Engineers, the Iron and Steel Institute of Japan and others. The significance of these conferences is highly valued as an occasion for presentation of research and discussion on the technology of plasticity. The total number of papers presented at conferences in the past ten years is over 3000.
The research areas covered encompass all processes and relevant properties of materials in the solid, mushy or powdered state, as well as theory of plasticity. In recent years as great changes occur in public circumstances, such as low economic growth, presentations on computer simulations and new processes or systems for small quantity production have increased in number. But rolling still predominates in the number of presentations; over 20% of the total of the past ten years.
Recent developments in the area of rolling are also remarkable, though they are not reviewed in this issue. Research and development over the past ten years have been oriented to consuming less energy and resources. The Schedule-free Rolling in hot strip mills and the Large Draft Rolling in cold tandem mills are examples of the new techniques developed and the basis of these techniques is crown and shape control. The crown and shape of rolled strip have come to be satisfactorily predictable by applying three-dimensional analysis. As these techniques demand a rolling mill of high shape controllability, many new types of rolling mill have been developed, such as the Double Chock Work Roll Bending Mill, the 6-Hi Mill, the Variable Crown Roll Mill, the Flexible Flatness Control Mill and the Pair Cross Mill. New operating systems for mills have been developed as well. The area of rolling is a typical example of great