PPT: Springs | Design of Machine Elements - Mechanical Engineering PDF Download

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Spring 
Definition: 
 The elastic body which deflects under the application of load and restores 
original shape by removal of force is called as spring. 
Functions of Springs:  
1) Absorb or control the energy due to 
either shock or vibrations 
2) Apply the forces 
3) Measures the forces 
4) Controls the motion 
5) Stores the energy, as in watches, toys 
Applications of Spring: 
1) Shock absorber, Railway buffers, 
Vibration dampers 
2) Brakes, Clutches, Spring loaded valves 
3) Watches, toys 
4) Spring balances, Gauges, Engine 
components 
5) Apply clamping forces in jigs & 
fixtures  
Classification of Springs:  
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Spring 
Definition: 
 The elastic body which deflects under the application of load and restores 
original shape by removal of force is called as spring. 
Functions of Springs:  
1) Absorb or control the energy due to 
either shock or vibrations 
2) Apply the forces 
3) Measures the forces 
4) Controls the motion 
5) Stores the energy, as in watches, toys 
Applications of Spring: 
1) Shock absorber, Railway buffers, 
Vibration dampers 
2) Brakes, Clutches, Spring loaded valves 
3) Watches, toys 
4) Spring balances, Gauges, Engine 
components 
5) Apply clamping forces in jigs & 
fixtures  
Classification of Springs:  
Spring 
Classification of Spring: 
The wire of cross section may be circular, 
square and rectangular depending on the 
type of loading and deflection required is 
made in the form of helix. The load 
applied on the spring is along the axis of 
helix. The major stress is induced in 
spring is torsional shear stress. 
1) Helical Springs:  
a) Helical Compression Springs:  
They take axial compressive 
load and coils are separated 
from each other. 
They are used in clutches, 
brakes, shock absorber.  
They take axial tensile load and 
coils are closed to each other. 
They are used in spring loaded 
safety valve, spring balance. 
b) Helical T ension Springs:  
c) Closed Coiled Helical Springs:  
The helix angle is less than 
10 °. Plane  containing each 
coil is nearly perpendicular 
to axis of helix. Small gap 
between two adjacent coils. 
c) Open Coiled Helical Springs:  
The helix angle is more than 
10 °. Large gap between two 
adjacent coils. 
2) Conical & Volute Springs:  
The circular or rectangular 
cross sectional wire forms in 
frustum of cone shape. They 
are used when increasing 
spring rate or stiffness is 
desired with the load. 
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Spring 
Definition: 
 The elastic body which deflects under the application of load and restores 
original shape by removal of force is called as spring. 
Functions of Springs:  
1) Absorb or control the energy due to 
either shock or vibrations 
2) Apply the forces 
3) Measures the forces 
4) Controls the motion 
5) Stores the energy, as in watches, toys 
Applications of Spring: 
1) Shock absorber, Railway buffers, 
Vibration dampers 
2) Brakes, Clutches, Spring loaded valves 
3) Watches, toys 
4) Spring balances, Gauges, Engine 
components 
5) Apply clamping forces in jigs & 
fixtures  
Classification of Springs:  
Spring 
Classification of Spring: 
The wire of cross section may be circular, 
square and rectangular depending on the 
type of loading and deflection required is 
made in the form of helix. The load 
applied on the spring is along the axis of 
helix. The major stress is induced in 
spring is torsional shear stress. 
1) Helical Springs:  
a) Helical Compression Springs:  
They take axial compressive 
load and coils are separated 
from each other. 
They are used in clutches, 
brakes, shock absorber.  
They take axial tensile load and 
coils are closed to each other. 
They are used in spring loaded 
safety valve, spring balance. 
b) Helical T ension Springs:  
c) Closed Coiled Helical Springs:  
The helix angle is less than 
10 °. Plane  containing each 
coil is nearly perpendicular 
to axis of helix. Small gap 
between two adjacent coils. 
c) Open Coiled Helical Springs:  
The helix angle is more than 
10 °. Large gap between two 
adjacent coils. 
2) Conical & Volute Springs:  
The circular or rectangular 
cross sectional wire forms in 
frustum of cone shape. They 
are used when increasing 
spring rate or stiffness is 
desired with the load. 
Spring 
Classification of Spring: 
3) T orsional Springs:  
The springs are wound in 
parabolic shape with constant 
pitch and lead angle. The 
decreasing number of coils 
results in increasing spring 
rate. 
The spiral springs are made of flat strip 
wound in the form of spiral and loaded in 
torsion. 
Spiral springs are used in mechanical 
watches, clocks. 
The helical torsional springs are made of a 
wire like compression spring and load is 
applied tangentially. They are subjected to 
torque about the central axis of spring coil. 
This induces bending stress in the wire. 
These springs are used in door hinges, 
automobile starters.  
4) Leaf Springs:  
A leaf spring is of semi-elliptical form and 
consists of leaves held together by means of 
clamps and bolts. These springs may carry 
lateral loads, brake torque, driving torque in 
addition to shock. These are used in 
automobile suspension. 
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Spring 
Definition: 
 The elastic body which deflects under the application of load and restores 
original shape by removal of force is called as spring. 
Functions of Springs:  
1) Absorb or control the energy due to 
either shock or vibrations 
2) Apply the forces 
3) Measures the forces 
4) Controls the motion 
5) Stores the energy, as in watches, toys 
Applications of Spring: 
1) Shock absorber, Railway buffers, 
Vibration dampers 
2) Brakes, Clutches, Spring loaded valves 
3) Watches, toys 
4) Spring balances, Gauges, Engine 
components 
5) Apply clamping forces in jigs & 
fixtures  
Classification of Springs:  
Spring 
Classification of Spring: 
The wire of cross section may be circular, 
square and rectangular depending on the 
type of loading and deflection required is 
made in the form of helix. The load 
applied on the spring is along the axis of 
helix. The major stress is induced in 
spring is torsional shear stress. 
1) Helical Springs:  
a) Helical Compression Springs:  
They take axial compressive 
load and coils are separated 
from each other. 
They are used in clutches, 
brakes, shock absorber.  
They take axial tensile load and 
coils are closed to each other. 
They are used in spring loaded 
safety valve, spring balance. 
b) Helical T ension Springs:  
c) Closed Coiled Helical Springs:  
The helix angle is less than 
10 °. Plane  containing each 
coil is nearly perpendicular 
to axis of helix. Small gap 
between two adjacent coils. 
c) Open Coiled Helical Springs:  
The helix angle is more than 
10 °. Large gap between two 
adjacent coils. 
2) Conical & Volute Springs:  
The circular or rectangular 
cross sectional wire forms in 
frustum of cone shape. They 
are used when increasing 
spring rate or stiffness is 
desired with the load. 
Spring 
Classification of Spring: 
3) T orsional Springs:  
The springs are wound in 
parabolic shape with constant 
pitch and lead angle. The 
decreasing number of coils 
results in increasing spring 
rate. 
The spiral springs are made of flat strip 
wound in the form of spiral and loaded in 
torsion. 
Spiral springs are used in mechanical 
watches, clocks. 
The helical torsional springs are made of a 
wire like compression spring and load is 
applied tangentially. They are subjected to 
torque about the central axis of spring coil. 
This induces bending stress in the wire. 
These springs are used in door hinges, 
automobile starters.  
4) Leaf Springs:  
A leaf spring is of semi-elliptical form and 
consists of leaves held together by means of 
clamps and bolts. These springs may carry 
lateral loads, brake torque, driving torque in 
addition to shock. These are used in 
automobile suspension. 
Spring 
Terms Used in Helical Spring: 
1) Solid Height/Solid Length: The product 
of total number of coils and diameter of 
wire. 
Where, n’ is total number of coils, d is 
diameter of spring wire. 
 
2) Free Length: The length of spring is free 
or unloaded. 
 
 
3) Spring Index: The ratio of mean 
diameter of coil to the diameter of spring 
wire. Generally spring index is taken from 5 
to 10. 
 
4) Spring Rate/Stiffness/Spring Constant: 
The load required per unit deflection of the 
spring. 
 
 
5) Pitch: The axial distance between 
adjacent coils in uncompressed state. 
 
 
Materials for Spring: 
Plain Carbon Steel, Alloy Steel, Corrosion 
Resistance Steel, Non Ferrous Spring 
Materials (Phosphor Bronze, Brass, Nickel 
Alloy and Beryllium Copper), Patented and 
Cold drawn steel wires, Oil Hardened and 
Tempered  spring steel wires (Chromium-
V anadium, Silicon-Manganese).