Helical Springs
Machine Design II
Prof. K.Gopinath & Prof. M.M.Mayuram
Design of Helical Springs
The design of a new spring involves the following considerations: • Space into which the spring must fit and operate. • Values of working forces and deflections. • Accuracy and reliability needed. • Tolerances and permissible variations in specifications. • Environmental conditions such as temperature, presence of a corrosive atmosphere. • Cost and qualities needed. The designers use these factors to select a material and specify suitable values for the wire size, the number of turns, the coil diameter and the free length, type of ends and the spring rate needed to satisfy working force deflection requirements. The primary design constraints are that the wire size should be commercially available and that the stress at the solid length be no longer greater than the torsional yield strength. Further functioning of the spring should be stable.
Stability of the spring (Buckling)
Buckling of column is a familiar phenomenon. Buckling of column is a familiar phenomenon. We have noted earlier that a slender member or column subjected to compressive loading will buckle when the load exceeds a critical value. Similarly compression coil springs will buckle when the free length of the spring is larger and the end conditions are not proper to evenly distribute the load all along the circumference of the coil. The coil compression springs will have a tendency to buckle when the
deflection (for a given free length) becomes too large. Buckling can be prevented by limiting the deflection of the spring or the free length of the spring.
Indian Institute of Technology Madras
Machine Design II
Prof. K.Gopinath & Prof. M.M.Mayuram
The behavior can be characterized by using two dimensionless parameters, critical length and critical deflection. Critical deflection can be defined as the ratio of deflection (y) to the free length (Lf) of the spring . The critical length is the ratio
Prof. K.Gopinath & Prof. M.M.Mayuram
Design of Helical Springs
The design of a new spring involves the following considerations: • Space into which the spring must fit and operate. • Values of working forces and deflections. • Accuracy and reliability needed. • Tolerances and permissible variations in specifications. • Environmental conditions such as temperature, presence of a corrosive atmosphere. • Cost and qualities needed. The designers use these factors to select a material and specify suitable values for the wire size, the number of turns, the coil diameter and the free length, type of ends and the spring rate needed to satisfy working force deflection requirements. The primary design constraints are that the wire size should be commercially available and that the stress at the solid length be no longer greater than the torsional yield strength. Further functioning of the spring should be stable.
Stability of the spring (Buckling)
Buckling of column is a familiar phenomenon. Buckling of column is a familiar phenomenon. We have noted earlier that a slender member or column subjected to compressive loading will buckle when the load exceeds a critical value. Similarly compression coil springs will buckle when the free length of the spring is larger and the end conditions are not proper to evenly distribute the load all along the circumference of the coil. The coil compression springs will have a tendency to buckle when the
deflection (for a given free length) becomes too large. Buckling can be prevented by limiting the deflection of the spring or the free length of the spring.
Indian Institute of Technology Madras
Machine Design II
Prof. K.Gopinath & Prof. M.M.Mayuram
The behavior can be characterized by using two dimensionless parameters, critical length and critical deflection. Critical deflection can be defined as the ratio of deflection (y) to the free length (Lf) of the spring . The critical length is the ratio