CAMS WITH SPECIFIED CONTOURS LUKHDHIRJI ENGINEERING COLLEGE MORBI CAMS WITH SPECIFIED CONTOURS BRANCH: MECHANICAL ENGINEERING SEMESTER: 3 YEAR: 2014-15   GUIDED BY: Prof. I.B. SHAH PREPARED BY: Agarwal Prasoon S (130310119001) Albad Ravindra C (130310119002) Gosai Anandpari K (130310119003)

Cam Cam - A mechanical device used to transmit motion to a follower by direct contact. Cam – driver; Follower - driven In a cam - follower pair, the cam normally rotates while the follower may translate or oscillate. Cams are used to convert rotary motion into reciprocating motion

Three elements of the cam

CLASSIFICATION OF CAMS (i) Based on the physical shape (a) Disk or plate cams

(b) Cylindrical cam

Translation Cam (Wedge Cam) Not very commonly used. The cam moves over and back, reciprocating motion, which drives the follower vertically.

CLASSIFICATION OF FOLLOWES Based on surface in contact (a) Knife edge follower (b) Roller follower (c) Flat faced follower (d) Spherical follower

KNIFE OR POINT EDGE FOLLOWER FLAT FACED FOLLOWER ROLLER FOLLOWER

(ii) Based on type of motion Oscillating follower Translating follower

(iii) Based on line of action Radial (in line) follower

(b) Off-set follower

(iv)According to the shape of follower Knife edge follower Roller follower Flat faced follower Spherical faced follower

Classification of CAM Mechanism Based on modes of Input / Output motion 1 Rotating cam –Translating follower 2 Rotating cam – Oscillating follower 3 Translating cam – Translating follower

. CAM Nomenclature

Cam profile : The outer surface of the disc cam. Base circle: The smallest circle drawn on the cam profile. Trace point: The center line of the follower roller or its equivalent.

Pitch curve: The locus of successive positions of the trace point as cam displacement takes place. Prime circle: The smallest circle drawn on the pitch curve from the cam center. Pressure angle: the angle between the normal to the pitch curve and the instantaneous direction of motion of the follower.

Cam terms Pitch point: The position of the pitch curve where the pressure angle is maximum. Pitch circle: The circle which passes through the pitch point.

Example of cam action

Cam-Valve

CAMS WITH SPECIFIED CONTOURS INTRODUCTION Based on the flank, cams are classified into two groups, Circular arc cam 2. Straight edged cam or Tangent cam ANALYSIS OF CAMS

Circular arc Cam: When the flanks of the cam connecting the nose and base circles are of convex circular arc, such cams are referred as circular arc cams.

Tangent cam: When the flanks between the nose and base circles are of straight and tangential to both the circles, then, the cams are called tangent cams.

These are usually symmetric about the centre line of the cam These are usually symmetric about the centre line of the cam. Generally, the following combinations of cam and follower are used. Circular arc cam with flat faced follower: (i) When the flat face of the follower has contact on the circular flank. (ii) When the flat face of the follower has contact on the nose. (b) Tangent cam with reciprocating roller follower: (i) When the roller has contact with straight flanks. (ii) When the roller has contact with the nose.

CIRCULAR ARC CAM WITH FLAT FACED FOLLOWER The figure below represents various main dimensions of circular arc cam.

(a) Expression for determining the displacement, velocity and acceleration of the follower when flat face of the follower has contact on the circular flank

(b) Expression for determining the displacement, velocity and acceleration of the follower when flat face of the follower has contact on the nose

TANGENT CAM WITH ROLLER RECIPROCATING FOLLOWER Tangent cams are made with straight flanks. A tangent cam is shown in figure below The flanks AB and IH are straight lines and tangent to the base circle at A and I and tangent to nose at B and I. The centre of the circular nose is P. The path of the centre of roller follower is shown by dotted line.

a. Expression for determination of displacement, velocity and acceleration of the roller follower when in contact on the straight flank

(b) Expression for determination of displacement, velocity and acceleration of the roller follower when in contact with nose

REFERECNCES: http://www.philadelphia.edu.jo/academics/mshabi/uploads/M%20500.ppt http://elearning.vtu.ac.in/17/e-Notes/10ME54/Unit8-YMS.pdf http://www.eng.utoledo.edu/~enikolai/3300-files/Cams-review.ppt http://www.camcoindex.com/svcman/moonbook.pdf