THE volute spring, long used in railroad work, is now being applied to automotive equipment. The more stringent demands on space and performance in the automotive field have made refinements in materials, design, and manufacture necessary.
Mr. Fuchs here presents a discussion of the design phase of the problem.
Gradually increasing spring rate (stiffness) and unequal stress distribution along the blade are the chief features of volute springs. Apart from scale factors, Mr. Fuchs says, rate increase and stress distribution depend only on the ratio of smallest to largest free coil radii and on the variation of free helix angles from coil to coil.
Use of nondimensional charts simplifies design, enables a rapid survey to be made without calculations, and gives a correct picture of loads and stresses.
The importance of the presetting operation is emphasized by the author. Layout of coiling form and presetting bowl are a major design item, for which a rational procedure is proposed.