Aim : seminar on any topic Aim : seminar on any topic of 4of 4thth semester semester

Name: hadolikar s.lName: hadolikar s.lBranch: ME Branch: ME Ro.no.1027Ro.no.1027

Subject: theory of machines

Topic : cam & followers

Concept & definition of cam followers

A cam is rotating a machine element which gives reciprocating or oscillating motion to the another element know as follower.

The cam & follower has a point or line contact constitute a higher pair.

According to surface contact

1 . Knife edged follower

According to motion of the follower

According to the path of motion of the followers

Offset follower

1 radial cam

2 cylindrical cam

3 wedge cam

Cylindrical cam

Wedge cam

1 .The most well known use of cams is in car engines. The Cam operated valve system can be found in modern car engines and incorporates a number of cams; the valves are opened by cams, four- and six-lobed cams govern the spark distribution and many car petrol oil pumps are cam driven.

2 . These are used in wall clock

3 . These are used in feed mechanism In automatic lathe machine

4. These are used in paper cutting machine.

5 . It is use in textile machine

Cam terminologyCam terminology The cam terminology used for drawing The cam terminology used for drawing

cam profile & displacement diagram .cam profile & displacement diagram .First we know the terms .First we know the terms .Base circle: It is the smallest circle can Base circle: It is the smallest circle can

be drawn to the cam profile.be drawn to the cam profile.Trance point: It is the reference point Trance point: It is the reference point

of the follower & is used to generate a of the follower & is used to generate a pitch curve . pitch curve .

Pressure angle : It represent include the Pressure angle : It represent include the angle at any point on the pitch curve angle at any point on the pitch curve between line or motion of the follower & between line or motion of the follower & normal to that point on the cam profile .normal to that point on the cam profile .

Pitch point : It is the point on the pitch Pitch point : It is the point on the pitch curve having maximum pressure anglecurve having maximum pressure angle

Pitch circle : It is a circle drawn from the Pitch circle : It is a circle drawn from the center of the cam through the pitch center of the cam through the pitch point. point.

Prime circle : it is the smallest circle can Prime circle : it is the smallest circle can be drawn from center of the cam & be drawn from center of the cam & tangent to pitch curve . tangent to pitch curve .

Cam angle : it is the angle of rotation of the Cam angle : it is the angle of rotation of the cam for a definite displacement of the cam for a definite displacement of the followers followers

Cam profile : it is the actual working surface Cam profile : it is the actual working surface of the cam with which the surface of the of the cam with which the surface of the follower is always in contact it transmit the follower is always in contact it transmit the required motion to the follower.required motion to the follower.

Types of motion of the Types of motion of the followerfollower

1.1. Uniform velocity or uniform motion. Uniform velocity or uniform motion.

2.2. simple harmonic motion.simple harmonic motion.

3.3. uniform acceleration & retardation.uniform acceleration & retardation.

1.1.Uniform velocity or uniform Uniform velocity or uniform motion. motion.

simple harmonic simple harmonic motionmotion

uniform acceleration & retardationuniform acceleration & retardation

Prob 1: draw the profile of disc cam Prob 1: draw the profile of disc cam to given uniform velocity motion to to given uniform velocity motion to the knife edged follower during the knife edged follower during outstroke of 60mm during 1outstroke of 60mm during 1stst half half revolution. The follower again turns revolution. The follower again turns to its original position with velocity to its original position with velocity during next half of three revolution . during next half of three revolution . The minimum radius of the cam is The minimum radius of the cam is 50mm & diameter of the cam shaft is 50mm & diameter of the cam shaft is 35mm. The axis of follower passes 35mm. The axis of follower passes through the axis of the cam.through the axis of the cam.

Given data:

out stroke of follower (s)=60mm

Minimum radius of the cam =50mmMinimum radius of the cam =50mm

diameter of the cam shaft = 35mmthe cam shaft = 35mm

Angle of outstroke=180Angle of outstroke=180

angle of return stroke=180angle of return stroke=180