Section D

Disc Springs (Washers) - Introduction (Continued) Rondelles à ressort (Belleville) – introduction (suite) DISC SPRING STACK COMPARED TO HELICAL SPRING Note that the same load is achieved at substantial reduction in space. Disc stacks may be designed for extremely high loads where coil springs are not feasible at all.

INTRODUCTION TO COST-SAVING, SPACE-SAVING DISC SPRINGS

Compared to a coil spring, a disc spring achieves economy in design, and reduces the cost of the overall assembly by the maximum utilization of space. The disc spring is unique among the various types of springs because it offers several dis tinct advantages over its counterparts. Among them are the following: 1.A choice of a wide range of load deflec tion characteristics, such as a straight line, progressive and regressive. 2. Flexibility in stack arrangement in order to achieve a desired performance. 3.Space saving. 4.Self-damping (especially when stacked in parallel). 5.Longer fatigue life. 6.Simplified inventory because an individ ual spring size can be used for a wide range of applications.

D

THEORETICAL VS. MEASURED CHARACTERISTIC OF A DISC SPRING

DISC SPRINGS MAY BE USED SINGLY OR IN COMBINATIONS

DISC SPRING CHARACTERISTICS

Stacked in Parallel TOTAL DEFLECTION= deflection of 1 disc TOTAL LOAD= load on 1 disc x no. of discs

Series TOTAL DEFLECTION=

Parallel-Series COMBINATIONS can be designed to accommo date virtually any load or deflection, and to ob tain progressive or re gressive characteris tics.

deflection of 1 disc x no. discs in stack

TOTAL LOAD= load on 1 disc

The characteristic of the individual disc spring is non-linear. Its shape depends on the ratio h/t. At the lower portion of the deflection range, the characteristic in prac tice departs slightly from the theoretical. When f/h >0.75, the characteristic in prac tice again departs increasingly from the theoretical because the disc springs roll upon one another or upon the supporting surface, and this leads to a continuous shortening of the lever arm. Disc springs of differing thickness can be

This is a graphic illustration of the values con tained in Table 1, page D42 The characteristic or load-deflection relationship depends on the ratio of cone height h to the thickness t (h/t). C = (characteristic) = h/t If C is small (up to 0.6), the graph is almost a straight line. If C is 1.4, the graph is nearly straight over a considerable range of deflection, and this is called a constant-load disc spring, and is shown above as a dotted line.

DISC SPRINGS 6 Styles

CATALOG 14

Page No's ● Metric - “AM” Series ...................... D52-D61 ● Inch - “Stainless Steel”.......................... D64 ● Inch - “AI” “SAI” Series.................. D48-D49 ● Inch - “SP/SSP” Series.......................... D50 ● Inch - “Contact Disc” ............................. D62 ● Inch - “AK” Series.................................. D51

stacked in series to obtain a progressively rising load. This effect is also obtained using same thickness springs but incrementally increasing the units in the stack. Care must be taken not to over-stress the spring in the stack. (Note: Friction forces between springs must be considered.)

D41

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