Machinery's Handbook, 31st Edition
350
Disc Springs DISC SPRINGS Performance of Disc Springs
Introduction.— Disc springs, also known as Belleville springs, are conically formed from washers and have rectangular cross section. The disc spring concept was invented by a Frenchman Louis Belleville in 1865. His springs were relatively thick and had a small amount of cone height or “dish”, which determined axial deflection. At that time, these springs were used in the buffer parts of railway rolling stock, for recoil mechanisms of guns, and some other applications. The use of disc springs will be advantageous when space is limited and high force is required, as these conditions cannot be satisfied by using coil springs. Load-deflection characteristics of disc springs are linear and regressive de- pending on their dimensions and the type of stacking. A large number of standard sizes are available from disc spring manufacturers and distributors, so that custom sizes may not be required. Therefore, disc springs are widely used today in virtually all branches of engineering with possibilities of new applications. Disc Spring Nomenclature.— Disc spring manufacturers assign their own part number for each disc spring, but the catalog numbers for disc springs are similar, so each item can often be identified regardless of manufacturer. The disc spring identification number is a numerical code that provides basic dimensions in millimeters. Identification numbers represent the primary dimensions of the disc spring and consist of one, two, or three num- bers separated from each other by dash marks or spaces. Disc spring manufacturers in the United States also provide dimensions in inches. Dimensions of several typical disc springs are shown in the following table. Basic nomenclature is illustrated in Fig. 1. Catalog Number (mm) Outside Diameter D (mm) Inside Diameter d (mm) Thickness t (mm) Equivalent Catalog Number (inch) 8-4.2-0.4 8 4.2 0.4 0.315-0.165- 0.0157 50-25.4-2 50 25.4 2 1.97-1.00-0.0787 200-102-12 200 102 12 7.87-4.02-0.472 Additional dimensions shown in catalogs are cone (dish) height h at unloaded condi- tion, and overall height H = h + t , that combines the cone height and the thickness of a disc spring.
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Fig. 1. Disc Spring Nomenclature Disc Spring Group Classification.— Forces and stresses generated by compression de- pend on disc spring thickness much more than on any other dimensions. Standard DIN 2093 divides all disc springs into three groups in accordance with their thickness: Group 1 includes all disc springs with thickness less than 1.25 mm (0.0492 inch). Group 2 includes all disc springs with thickness between 1.25 mm and 6.0 mm (0.0492 inch and 0.2362 inch). Group 3 includes disc springs with thickness greater than 6.0 mm (0.2362 inch). There are 87 standard disc spring items, which are manufactured in accordance with DIN 2093 specifications for dimensions and quality requirements. There are 30 standard disc spring items in Group 1 . The smallest and the largest disc springs in this group are
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