Extrusion Dies for Plastics and Rubber

Design and Engineering Computations (Print-on-Demand)

Bearbeitet von Walter Michaeli

überarbeitet 2003. Buch. 362 S. Hardcover ISBN 978 3 446 22561 9 Format (B x L): 17,3 x 24,5 cm Gewicht: 808 g

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CARL HANSER VERLAG

Walter Michaeli

Extrusion Dies for Plastics and Rubber Design and Engineering Computations

3-446-22561-7

www.hanser.de

Preface to the Third Edition During my last visit to Medellin, Colombia, on occasion of the 10th anniversary of the ICIPC, a thriving plastics and rubber research institute, I met many young and eager students who knew my name because they had studied the book on extrusion die design. They asked many questions and I could not say good-bye without being photographed showing me at the center of their group. I enjoyed that for two reasons: first, this event showed that the book has reached acceptance even far away from my hometown. Second, it was important to learn that those young men and women enjoyed studying the book on their way to qualify for their professional life. But this book has also been written for the people who need daily support in their practical work applications in industry and science. Twelve years have gone by since the second edition of this book was published, years with visible changes and innovations in the field of extrusion and die design. For example, spiral mandrel dies have existed for more than three decades, but some functionalities have changed. Today, we place the spiral on a flat surface and feed it from the side. And when we pile a couple of those systems on top of each other, the result is the so-called stack die, which provides several advantages over classical coextrusion dies with annular slits. We incorporated this new development in Chapter 5. It may be the dream of an extrusion die designer to process all of the material, processing, and geometry data of the final product with a computer and end up with a fully designed flow channel which facilitates the optimum flow distribution. In studying this book, the reader will realize that finite element analysis is a key to fulfilling this dream, but the proper description of the viscoelastic properties of the extruded materials is still a challenge for rheologists and engineers. Nevertheless, significant steps have been made in this direction. For viscous flow, that goal has almost been reached. Therefore, a new chapter on optimization of extrusion die performance with computers was integrated into this third edition. I would like to thank my co-workers, Dr.-Ing. Boris Rotter, head of the IKV extrusion department, and Dipl.-Ing. Stefan Kaul, research engineer in this department, for their support and active help in reviewing and improving this book with their expertise. Many of the results presented in this book were produced by students at the Institute during the research for their diplomas. Much gratitude also goes to those who provided many suggestions and help; in particular, the members of the IKV advisory committees: Extrusion, Blow Molding, and Rubber Technology. Many research and development projects of IKV form the basis of some of the relations documented in the book. They were made possible by the cooperative research between the industry and IKV, by the support and funding of the Arbeitsgemeinschaft industrieller Forschungsvereinigungen Otto von Guericke e.V. (AiF) in Cologne, the Deutsche Forschungsgemeinschaft (DFG), Bonn-Bad Godesberg, and the Federal Ministry for Education, Research and Technology (BMBF) in Berlin, respectively Bonn and the European Commission, Brussels. Last but not least, I woud like to thank Dr. Wolfgang Glenz of Hanser, Munich, for so many years of excellent and active cooperation and for his vital insight. Such insight is appreciated by technical authors like myself, who have a rather challenging job, which at least nourishes our families, parallel to writing books. All of these contributing factors make things easier to write a book like this. Aachen, Germany, 2003

Walter Michaeli

Preface to the First Edition In this book an attempt is made to present to the practitioner and to the student a broad picture of all extrusion dies for plastics. In pursuing that objective the various types of dies and their specific features are discussed, guidelines for their design given and approaches to computational engineering analyses and its limitations demonstrated. This is even more important in view of the increasing efforts made by the industry as well as academia, starting in the recent past and continuing in the present, to model the transport phenomena (flow and heat transfer) in the extrusion die mathematically. These important projects are motivated primarily by the demand for higher productivity accompanied by better product quality (i.e. dimensional accuracy, surface quality) of the extruded semifinished goods. Purely empirical engineering methods for extrusion dies are becoming unacceptable at an increasing rate because of economical considerations. The design of the flow channel takes a focal position in the engineering process of extruder dies. This book starts by identifying and explaining the necessary material data for designing the flow channel. The derivation of basic equations permits estimates to be made of pressure losses, forces acting on the flow channel walls, velocity profiles, average velocities etc. in the flow channel. The simple equations that are useful for practical applications are summarized in tables. For the majority of extrusion dies these equations are sufficient to arrive at a realistic design based upon rheological considerations. Approaches to calculating the velocity and temperature fields using finite difference and finite element methods (FEM) are also discussed because of their increasing importance in the design of extrusion dies. The various types of single and multiple layer extrusion dies and their specific features are highlighted in detail in Chapters 5 und 6, followed by a review of the thermal and mechanical design considerations, and comments pertinent to the selection of material for extrusion dies and to their manufacture. A discussion of handling, cleaning and maintenance of extrusion dies as well as of devices for sizing of pipes and profiles concludes the book. At the end is a comprehensive list of references. The book was written during my activity as head of the Extrusion and Injection Molding Section at the Institut fuer Kunststoffverarbeitung (IKV) at the RheinischWestfaelische Technische Hochschule Aachen Institute for Plastics Processing at the Aachen Technical University, Aachen, West Germany, Director: Prof. Dr.-Ing. G. Menges). I had access to all importand results of the research at the IKV in the field of engineering of extrusion dies. I wish to extend my thanks to my former and present colleagues at the IKV, in particular Messrs. J. Wortberg, A. Dierkes, U. Masberg, B. Franzkoch, H. Bangert, L. Schmidt, W. Predoehl, P.B. Junk, H. Cordes, R. SchulzeKadelbach, P. Gelsbuesch, P. Thienel, E. Haberstroh, G. Wuebken, U. Thebing, K. Beiss and U. Vogt whose research work was essential in the preparation of the text and also to all other colleagues who contributed and to the students and graduate students of the Institute. But forem lost, I wish to thank Prof. Dr.-Ing. G. Menges for encouraging me to prepare this book and for his ceaseless help, promotion and support which made it possible for me to complete it. Further thanks are extended to a number of representatives of the plastics industry, in particular to the members of the Section Extrusion and Extrusion Blow Molding of the Advisory Board of the Foerdervereinigung (Sponsors Society) of the IKV. Many of the Research and development projects of the IKV which are referred to in this book and which because the basis for some of the facts presented in it, were only made possible financially by the joint research between industry and the IKV, support by the Arbeitsgemeinschaft Industrieller Forschungsvereinigungen (AIF), Co-

logne, the Deutsche Forschungsgemeinschaft (DFG), Bonn-Bad Godesberg and the Ministry for Research and Technology (BMFT), Bonn. This book was first published in German in 1979. The book in your hands is the first English translation based on this slightly revised 1979 edition. We have added an alphabetic index and checked the list of references to make sure that the most important references in English are easily identified. ‘Life goes on’ – also in extrusion tooling – so the list of references is completed by publications since 1979. I wish to thank all who made the English version possible: The Society of Plastics Engineers (SPE) for sponsoring this book, Dr. Herzberg for translating, Dr. Immergut and Dr. Glenz of Hanser for coordinating, Dr. Hold of Polymer Processing Institute – Stevens Institute of Technology, Hoboken, New Jersey, for being the technical editor, and Hanser for publishing. Heppenheim, W. Germany August 1983

Walter Michaeli