21 June 2016

What is mechanical spring?

Spring is defined as an elastic machine element that deflects under the load action and returns to its original shape when the load is removed.

Functions of spring 

  • To absorb shock and vibration
  • To store energy
  • To measure force
  • Spring is used to apply force and control the motion

Types of Spring 

Spring is classified by its shape may be a wire helical coil. The most popular type of spring is the helical spring.

Helical spring is sometimes classified as spring close-coiled and spring open-coiled.
  1. When the spring wire is coiled so close and its helix angle is very small, a helical spring is said to be close-coiled spring. Usually, a helix angle is less than 10 degrees.
  2. A helical spring is said to be open-coiled spring, when the spring wire is coiled in such a way, that there is a large gap between the adjacent coil and its helix angle is large. Usually, a helix angle is more than 10 degrees. 
Two basic types of helical springs are following below :
  1. Compression Spring
  2. Extension Spring
Both this type of helical spring have the following advantages :
  • They are easy to manufacture.
  • They are cheaper than other types of spring.
  • Their reliability is high.
  • The deflation of spring is linearly propositional to the force acting on the spring. 
Due to the above advantages, the helical spring is popular and extensively used in a number of applications.

Helical spring
Helical Spring

Helical Torsion Spring 

The term torsion is somewhat misleading because the wire is subjected to bending stress.
The construction of this type of spring is similar to that of the compression or extension spring, expect the ends to be formed in such a way that the spring is loaded around the axis of a coil by a torque.

The helical torsion spring is used to transmit torque in the machine to a specific component. Helical torsion spring is used in door-hinges, brush-holders, starters for automobiles and door locks.

Helical torsion spring
Helical torsion spring

Multi-leaf or Laminated Spring 

This spring is made up of a series of flat plates, usually in the semi-elliptical form. The flat plates are called leaves, the length of the leaves varies, the leaves are held together by means of U-bolts and a centre clip.

The longest leaf is called the master leaf and it bends at the both of two ends. The leaves of multi-leaf springs are subjected to bending stress. 

Multi-leaf spring is commonly used for vehicle, truck and rail wagon suspension.

Multileaf spring
Multileaf spring