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Handling Machining Assembly Control

M M M

Pneumatics Electronics Mechanics Sensorics Software

Hesse The Fluidic Muscle in Application150 practical examples using the Pneumatic Muscle

Chinese English French German Russian Spanish Blue Digest on Automation54178

Hesse The Fluidic Muscle in Application

Handling Pneumatics

Stefan Hesse

The Fluidic Muscle in Application150 practical examples using the Pneumatic muscle

Blue Digest on Automation

Blue Digest on Automation 2003 by Festo AG & Co.KG Ruiter Strae 82 D-73734 Esslingen Federal Republic of Germany Tel. 0711 347-0 Fax 0711 347 2155 All texts, representations, illustrations and drawings included in this book are the intellectual property of Festo AG & Co.KG, and are protected by copyright law. All rights reserved, including translation rights. No part of this publication may be reproduced or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior written permission of Festo AG & Co.KG

Preface

How does a muscle actually function? Is it technically possible to reproduce a muscle? This question has already robbed many an inventor and project manager of sleep. What is possible mechanically and is it chemically and physically feasible? As far back as 1872, the German professor Franz Reuleaux (1829-1905) described a flexible, pneumatic actuator. Since then all sorts of things have been tried: Muscles on the basis of memory metal, electrochemical actuators, polymer gels and electric motors combined with high ratio subminiature gears. To date, only very few solutions have found their way into everyday industrial life. Many are on hold in laboratories. Amongst the few durable solutions is the Fluidic Muscle from Festo, which is the principle performer in this book. It consists of an advanced high performance material and creates powerful and fast movements in a new way. An old idea has caught on in a high-tech era. Since the muscle can also be operated using water, it is probably more apt to speak of a fluidic actuator in general rather than a pneumatic muscle, even though compressed air will primarily be the medium used. In this book, a disproportionate view of the Fluidic Muscle will generally be shown in order to highlight its importance. In reality, a Muscle with an internal diameter of, for example, 10 mm takes up relatively little space. This is also an advantage when it comes to subsequent installation into existing machine structures. It is probably too early to fathom all the areas where the Fluidic Muscle will one day be in use. Nevertheless, this artificial Muscle is an actuator with a very interesting future for various reasons and there are already a number of applications with encouraging positive results. All the same, it is still in a status nascendi. This book is intended to provide suggestions for the use of the Muscle and to explain its function, point out the advantages and disadvantages and to provide an idea of suitable areas of application. I should like to thank Thomas Dehli, B.Sc. (Civil Engineering) and Manfred Moritz (both Festo) for their kind support with writing of this book. Stefan Hesse

Preface Contents 1 Membrane construction in nature and technology . . . . . . . . . . . . . . . . . . . . . 9 2 Example: Biological muscle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3 Technology and characteristics of the Fluidic Muscle . . . . . . . . . . . . . . . . . . 20 4 Muscle-type construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 5 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 5.1 Lifting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 5.2 Gripping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 5.3 Pressing and punching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 5.4 Pumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 5.5 Clamping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 5.6 Adjusting and positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 5.7 Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 5.8 Arm and leg movements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 5.9 Checking and testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 5.10 Driving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 5.11 Oscillation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 5.12 Braking and stopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 5.13 Transporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 5.14 Distributing and branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 5.15 Machining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 5.16 Unwinding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 5.17 Dosing and portioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Index of technical terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

1 Membrane constructions in nature and technology

By membrane we understand a thin, two-dimensional structure of a certain elasticity, which can be subjected to tension and stabilised by means of a gas air or fluid (water). The sheathing, outer medium and filler form a constructional system. In biology, a membrane refers to a skin, which for the most part grows into a porous septum and permits the movement of matter in both directions. All cell walls for example, are grown in the form of a membrane. Blood vessels are an example of this. More constructional membranes for example, are the vocal sacs of the aquatic frog. These consist of very strong cellular tissue and are pressurised by internal pressure, thereby forming an inflated spherical shape. The soft bodies of snails, worms and caterpillars typify tubular constructions stiffened by internal pressure. The sealing skins in this case are formed in such a way that when combined with the internal excess pressure, a shape typical of a particular species is produced. Membranes therefore play an extremely important role in living things. In the case of plants, there are for instance the epidermal water blisters (part of the epidermis) of the stems of crystalline plants. These cells are also subject to high internal pressure and they stabilise their form in this way. Pneumatic inflatable buildings are designed according to this principle. In technology, the term pneu refers to a system, whereby a sheathing which is purely subject to tension covers a filling. Typical pneus are air balloons, soap bubbles, inflated buildings, tyres, firehoses and domed membranes in the form of canopies for highly sensitive radar scanners. In these cases a state of tension exists in the homogenous membrane which is equal in all directions. Pneumatic lifting cushions in ring-shaped or rectangular form also come under this heading. These expand if compressed air is applied. This expansion effect is for instance used for lifting, gripping, sealing and pressing. Cushions of this type are made of synthetic reinforced rubber, polyurethane, neoprene coated polyamide, also reinforced with steel-cord or aramide, as well as other materials and fillers. However, the function of such cushions different to that of the Fluidic Muscle from Festo, because in this case the action of expansion is converted into tensile force, as you will see. An application for a cushion is shown in fig. 1-1. The cushion lifts a support plate. Pressures of up to 7 bar are applied (depending on design and size) and fairly high stroke forces are generated. In the pressureless state, the height of the cushions is greatly reduced. Cushions of this type can also be stacked. In this case, the stroke is increased in line with the addition of individual strokes. This method can for example be used to lift damaged aircraft or tanks. However, the cushion itself is without a guide and requires external elements for guiding or displacing. Many applications are purely for limited occasional use in emergency systems, accidents, lifting and sealing functions and are therefore not subject to continual frictional wear.

1 Membrane constructions in nature and technology

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Fig. 1-1 Lifting plate with pneumatic cushion drive 1 2 3 4 5 6 7 Pneumatic cushion Lifting plate Guide bush Guide column Stop bush Base plate Inlet connection piece

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Wherever objects are retained with the help of frictional forces, frictional wear to a lesser or greater extent is the result, with a corresponding effect on service life. Rubber tubing on the other hand is used for a wide range of different functions in industry. In the past, fire hoses were often used by joiners and cabinet makers as a means of supplying energy in bonding presses. Fig. 1-2a shows an example of how tubing can be installed in helical form in order to clamp cylindrica