Transcript Slide 1
Design of Helical spring 29 AUG 08 1 (12) What is helical spring Helical spring is a spiral wound wire with a constant coil diameter and uniform pitch. Function of Helical spring Used to store energy and subsequently release it To absorb shock To maintain a force between contacting surfaces 29 AUG 08 2 (12) Design consideration of helical spring 29 AUG 08 3 (12) Nomenclature of Helical spring C = Spring Index D/d d = wire diameter (m) D = Spring diameter (m) Di = Spring inside diameter (m) Dil = Spring inside diameter (loaded ) (m) E = Young's Modulus (N/m2) F = Axial Force (N) G = Modulus of Rigidity (N/m2) K W = Wahl Factor = [(4C-1)/(4C+5)}]+ (0,615/C) L 0 = Free Length (m) L s = Solid Length (m) n t = Total number of coils n = Number of active coils p = pitch (m) y = distance from neutral axis to outer fibre of wire (m) τ = shear stress (N/m2) τ max = Max shear stress (N/m2) θ = Deflection (radians) 29 AUG 08 4 (12) Spring material 1. High carbon steel • Music Wire (ASTM A228) Hard Drawn (ASTM A227) High Tensile Hard Drawn (ASTM A679) Oil Tempered (ASTM A229) Carbon Valve (ASTM A230) • • • • 2. Alloy spring steel • • Chrome Vanadium (ASTM A231) Chrome Silicon (ASTM A401) 3. Stainless steel • • • 29 AUG 08 4. Copper based alloy Phosphor Bronze (Grade A) - ASTM B159 Beryllium Copper - ASTM B197 Monel 400 (AMS 7233) Monel K500 (QQ-N-286 5. Nickel based alloy A286 Alloy Inconel 600 (QQ-W-390) Inconel 718 Inconel X-750 (AMS 5698, 5699) AISI 302/304 - ASTM A313 AISI 316 - ASTM A313 17-7 PH - ASTM A313(631) 5 (12) Effect of End treatment. 29 AUG 08 6 (12) The module calculates the following design parameters: 1. Outer Diameter (Do) 2. Spring Index (C) 5. Maximum load 6. Corrected maximum stress index range is 4 to 12 3. Slenderness ratio 7. Uncorrect maximum stress 4. Spring rate (k) 8. Wahl correction factor 29 AUG 08 7 (12) 9. Maximum deflection 10. Spring mass 11. Wire length 29 AUG 08 12. Shear stress 13. uncorrected Shear stress 14. Natural frequency 8 (12) CHECKING 1. Stability of spring (buckling) 2. Fatigue loading 29 AUG 08 9 (12) Spring testing machine 29 AUG 08 10 (12) 29 AUG 08 11 (12)