Mechanical Actuating System Used in Mechatronics.

Mechanical Actuating System

Mechanisms are devices which are used to convert the motion from one form to other required forms. examples, transform linear motion into rotational motion, or motion in one direction to move in a direction at a right angle, a linear reciprocating motion into rotary motion, as in the internal combustion engine where the reciprocating motion of the piston is converted into rotation of the crank and hence the drive shaft.

Mechanical elements can include the use of linkage, cams, gear rack-pinion, chain, belt drives. Many of the action which previously was obtained by the use of the mechanism are, however, often now days being obtained as a mechatronics approach by the use of a microprocessor system. The mechatronics approach has resulted in a simplification and often a reduction in cost. while electronics might now be used often for many functions that previously were fulfilled by mechanism, the mechanism might still be used to provide such functions as:

1. force amplification; given by lever 
2. change of speed; given by gear
3. a particular type of motion; given by quick return mechanism.

The motion of any rigid body can be considered to be a combination of translation and rotational motion. by considering the three dimensions of space.

1. Translational motion can be considered to be a movement which can be resolved into components along one or more of the three axes
2. A rotational motion can be considered as a rotation which has component rotating about one or more of the axes

Degree of freedom and constraints

A body that is free in space can move in three independent, mutually perpendicular directions and rotate in three ways about direction, then it is said to have six degrees of freedom. 

The degree number of freedom is the number of components of the motion that are required in order to generate motion. the problem in design is often to reduce the number of degree of freedom and this requires an appropriate number and orientation of the constraints. without any constrain a body would have six degrees of freedom.

The cam shape required to produce a particular motion of the follower will depend on the shape of the cam and the type of the follower used. Cams are the mechanical devices which are used to generate curvilinear or irregular motion of the mechanical elements. they are used to convert rotary motion into oscillatory motion or vice versa. as the cam rotates so the follower is made to rise, dwell and fall, the length of times spent at each of these positions depending on the shape of the cam.

Classification of Cams.

1. Wedge and flat cams:                                                                  A wedge cam has a wedge of specified contour and has translational motion. The follower can either translate or oscillate. a spring is used to maintain the contact between the cam and the follower.
   

           

1. Plate cam:                                                                                    The follower moves in a radial direction from the centre of the rotation of the cam. the follower reciprocates or oscillates in a plane normal to the cam axis.
   

Cylindrical Cam: A cylinder has a circumferential contour cut in the surface and the cam rotates about the axis. the follower motion is either oscillating or reciprocating type.

 Applications of Cams:

      Cams are widely used in the automation of the machinery, gear cutting machines, screw machine, printing press, textile industry, automobile engine valve

1. Cams in automatic lathes 
2. Automatic copying machine
3. I.C engines