Mechanical Springs , Functions and application, Types of springs, Selection of material

           Mechanical Springs

An elastic machine element, which deflects under the action of the load and returns to its original shape when the load is removed, is known as mechanical springs.

Function and applications of spring:- 

              The important functions and applications of springs are as follows- 

1- Springs are used to absorb shocks and vibrations i.e. vehicle suspension springs, railway buffer springs etc.

2- Springs are used to store energy . Ex - spring used in clock, toys, circuit breakers and starters.

3- Springs are used to measure force. Ex - springs used in weighing balance and scales.

4- Springs are used to apply force and control motion.

Factors on which selection of material of spring wire depends- 
               Material for spring wire is selected by considering following features :- 
1- The load acting on the spring.
2- The range of stresses developed in the spring.
3- The limitations on mass and volume of spring.
4- The expected fatigue life of spring .
5- The environment conditions such as tem and corrosive atmosphere.
6- The severity of deformation encountered while making the spring.

Springs Materials:- 
1- Hard drawn spring steel wire.
2- Music wire.
3- Oil hardened and tem spring steel wire.
4- Alloy steel wire.
5- Stainless steel wire.

        -: Types of Springs :- 

Generally springs are of following five types - 

1- Helical springs

2- Conical and volute springs

3- Torsion springs

4- Laminated or leaf springs ( Flat spring or carriage spring ) 

5- Disc or Belleville spring

1- Helical springs:- 

                                    A spring which are made from wire , usually of circular cross-section which is bent in the form of a helix is called helical spring.

            This type of springs is used for carrying compression , extension and torque forces.

            

2- Conical and volute springs:- 

                                                   Conical springs are compression springs which are helically coiled round wires forming a tapered or conical shape. They are used to provide balance and reduce the solid hight by the coils telescoping into each other.

           A  volute spring is a compression spring in the form of a cone . Under compression the coils slide past each other, thus enabling the spring to be compressed to a very short length in - comparison with what would be possible with a more conventional helix spring.

      The major stresses produced inconical and volute springs are shear stress due to twisting.

3- Torsion springs:- Torsion springs may be of helical or spiral type, helical type is used where applied load tends to wind up the spring. 

    Spiral type is used where the load tends to increase the number of coils. 

Torsion springs are used in applications which rotates less than 360 degree . These springs have either clockwise or anticlockwise rotation
 .  

4- Laminated/ Leaf springs:- 

                                                     Leaf springs are also called semi - elliptical spring or cart spring . It is one of the oldest form of spring. Leaf springs are long and Flat slender arc shaped. 

 These types of springs are used in vehicle suspension and the major stresses produced in leaf springs are tensile and compressive stresses.

5- Disc / Belleville spring:- 

                                                 A Belleville spring also known as a coned disc spring, Conical spring washer, disc spring , cupped spring washer. 

Belleville washers are mostly coin shape spring with a hole in center. This spring required less space for installation but can bear a very large load  . These springs have more advantages compare to other springs.