Forces and Stresses involved in Jaw crusher operations like crushing of stones etc

1. Case Study
On:-
Design of Jaw crushers
Group Members:-
1.Tahir Ali- 09
2.Akash Jadhav- 29
3.Utkarsh Sorte- 34
Guided By:-
Prof. V.P. Kulkarni
Prof. Bhavna M.M.

2. A jaw crusher uses compressive force for breaking of particle. This mechanical pressure is achieved by the two
jaws of the crusher of which one is fixed while the other reciprocates. A jaw or toggle crusher consists of a
set of vertical jaws, one jaw is kept stationary and is called a fixed jaw while the other jaw called a
swing jaw, moves back and forth relative to it, by a cam or pitman mechanism, acting like a class II lever or
a nutcracker. The volume or cavity between the two jaws is called the crushing chamber. The movement of
the swing jaw can be quite small, since complete crushing is not performed in one stroke. The inertia
required to crush the material is provided by a weighted flywheel that moves a shaft creating an
eccentric motion that causes the closing of the gap. Principle of jaw crusher is that the movable jaw has its
maximum movement at the top of the crushing, and minimum movement at the discharge point.
Types of jaw crusher:-
1. Single Toggle Jaw Crusher
2. Double toggle jaw crusher
Jaw Crusher

3. Fig.-Jaw Crusher

5. Fig.- Double toggle jaw crusher

7. Fig.- Single Toggle Jaw Crusher

8. Calculation of various forces on Single toggle jaw crusher
The method used includes the following:
(i)A static force analysis that neglects the frictional and inertia forces is performed.
(ii)All the forces and moments are assumed to be coplanar.
(iii)The analysis proceeds by considering the equilibrium of the
forces acting at the moving joints of the mechanism and relating them to the input torque as
well as the load torque.

9. Fig. 1- Kinematic Model of Single toggle jaw crusher

10. In the kinematical model of the single toggle jaw crusher, which is illustrated in Figure , the eccentric
shaft is modelled as a short crank, of length r2 , that continuously rotates about a fixed axis, at O2 .
The swing jaw is modelled as the coupler link O3O4 , of length r3 , which moves with a complex planar
motion that has both rotational and translational components. The toggle link is modelled as the
rockerO4O1 , which oscillates about the fixed axis at O1 . The fixed jaw is considered to be an integral
part of the frame of the machine.

11. Table 1- Data for a PE 400 by 600 single toggle jaw crusher (mm).

13. Fig. 2- Model for static force analysis of the single toggle jaw crusher.

15. Fig.3- Free-body diagrams of the crank, the coupler, and the rocker.

17. Fig. 4- Balance of moments on the crank.

19. Fig. 5- Variation of force transmission ratio with crank angle θ2.

20. Required Power and other
parameters
of Single Toggle
Jaw Crusher