Call on 01202 339559

Schnorr Disc Springs

Disc Spring Engineering
Maximum load - minimum space - maximum flexibility

# DIAGRAM OF A DISC SPRING

Figure 1 - click to enlarge

Symbols and Units

 Symbols Unit Designation De mm Outside diameter Di mm Inside diameter Dw mm Diameter at the root of slots in a disc spring Do mm Diameter of centre of rotation E N/mm2 Young’s modulus F N Spring force of a single spring F1, F2, F3 N Spring force for deflections s1, s2, s3 Fc N Calculated spring force of a single spring when flat Fges N Spring force of a spring set or stack ΔF N Force lost in setting K1, K2, K3, K4 Constants for calculations LO mm Unloaded length of the spring stack or spring sets L1, L2, L3 mm Length of the loaded spring stack or spring set for forces F1, F2, F3 Lc mm Calculated length of the spring stack or set when springs are flat N Number of cycles to failure R N/mm Spring rate W N/mm Spring work ho mm Cone height of an unloaded single spring (calculated ho = lo – t) ho' mm Cone height of an unloaded spring with reduced thickness t’ (and contact flats, calculated ho=lo– t) i No. of single springs or sets in series in a stack lo mm Height of an unloaded spring stack n No. of parallel springs in a set s mm Deflection of a single spring s1, s2, s3 mm Deflections relative to loads F1, F2, F3 sges mm Deflection of a spring set or stack t mm Thickness of individual t' mm Reduced spring thickness for springs with contact flats (group 3) WM, wR Friction factors δ= De/Di Diameter ratio µ Poisson’s ratio (for spring steel = 0.3) σ N/mm2 Calculated stress σOM, σl, σll, σlll, σlv N/mm2 Calculated stress at points OM, I, II, III and IV as per figure 1 σo N/mm2 Calculated maximum stress for springs with dynamic loads σu N/mm2 Calculated minimum stress for springs with dynamic loads σh N/mm2 Stress range for the working stroke of dynamically loaded springs σO N/mm2 Maximum stress for fatigue resistance σU N/mm2 Minimum stress for fatigue resistance σH = σ0 - σU N/mm2 Permissible stress range for fatigue resistance