Springs - Springs Chapter 19 Material from Mott, 2003,...

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1 Springs Chapter 19 Material from Mott, 2003, Mechanical Design of Machine Elements Springs A spring is a flexible element used to exert a force or a torque and, at the same time, to store energy. The force can be a linear push or pull, or it can be radial, acting similarly to a rubber band around a roll of drawings. The torque can be used to cause a rotation, for example, to close a door on a cabinet or to provide a counterbalance force for a machine element pivoting on a hinge. Mott, 2003, Mechanical Design of Machine Elements
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2 Kinds of Springs Springs can be classified according to the direction and the nature of the force exerted by the spring when it is deflected. Springs are classified as push, pull, radial, and torsion. Helical compression springs are typically made from round wire, wrapped into a straight, cylindrical form with a constant pitch between adjacent coils. Square or rectangular wire may also be used Kinds of Springs con’t Without an applied load, the spring’s length is called the free length. When a compression force is applied, the coils are pressed more closely together until they all touch, at which time the length is the minimum possible called the solid length. Kinds of Springs con’t Helical extension springs appear to be similar to compression springs, having a series of coils wrapped into a cylindrical form. However, in extension springs, the coils either touch or are closely space under the no-load condition.
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3 Types of Springs Types of Springs
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4 Kinds of Springs con’t The drawbar spring incorporates a standard helical compression spring with two looped wire devices inserted through the inside of the spring. With such a design, a tensile force can be exerted by pulling on the loops while still placing the spring in compression. Kinds of Springs con’t A torsion string is used to exert a torque as the spring is deflected by rotation about its axis. The common spring-action clothespin uses a torsion spring to provide the gripping action. Leaf springs are made from one or more flat strips of brass, bronze, steel, or other materials loaded as cantilevers or simple beams. They can provide a push or pull force as they are deflected from their free condition. Large forces can be exerted within a small space by leaf springs. Kinds of Springs con’t A Belleville spring has the shape of a shallow, conical disk with a central hole. It is sometimes called a Belleville washer because its appearance is similar to that of a flat washer. A very high spring rate or spring force can be developed in a small axial space with such springs. By varying the height of the cone relative to the thickness of the disk, the designer can obtain a variety of load-deflection characteristics.
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5 Kinds of Springs con’t Garter springs are coiled wire formed into a continuous ring shape so that they exert a radial force around the periphery of the object to which they are applied. Either inward or outward forces can be
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Springs - Springs Chapter 19 Material from Mott, 2003,...

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