Rizvi College of Engineering Subject Kinematics of Machinery

Rizvi College of Engineering Subject : Kinematics of Machinery Sem – IV Mechanical Engineering Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Cam mechanism Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering CAM • convert rotary motion into reciprocating motion Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering APPLICATIONS Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of CAM Mechanism Based on modes of Input / Output motion • Rotating cam – Translating follower • Rotating cam – Oscillating follower • Translating cam – Translating follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Rotating cam – Translating follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Rotating cam – oscillating follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Translating cam – Translating follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of followers According to the shape of follower • Knife edge follower • Roller follower • Flat faced follower • Spherical faced follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of followers According to the shape of follower • Knife edge follower • Roller follower • Flat faced follower • Spherical faced follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of followers According to the shape of follower • Knife edge follower • Roller follower • Flat faced follower • Spherical faced follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of followers According to the shape of follower • Knife edge follower • Roller follower • Flat faced follower • Spherical faced follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of followers According to the shape of follower • Knife edge follower • Roller follower • Flat faced follower • Spherical faced follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering According to the path of motion of follower • Radial follower • Offset follower Prof. Mannoj Paul (Kinematics of

Rizvi College of Engineering According to the path of motion of follower • Radial follower • Offset follower -the motion of the follower is along an axis passing through the centre of the cam Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering According to the path of motion of follower • Radial follower • Offset follower - the motion of the follower is along an axis away from the axis of the cam center Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of cams • Radial or disc cam • Cylindrical cam • End cam Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of cams • Radial or disc cam • Cylindrical cam • End cam - the follower reciprocates or oscillates in a direction perpendicular to the cam axis Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of cams • Radial or disc cam • Cylindrical cam • End cam -the follower reciprocates or oscillates in a direction parallel to the cams axis Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Classification of cams • Radial or disc cam • Cylindrical cam • End cam - It is also similar to cylindrical cams, but the follower makes contact at periphery of the cam Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Cam Terminology • Base circle (Rb) – smallest circle that can be drawn tangent to the physical cam surface • Prime circle (Rp) – smallest circle that can be drawn tangent to the locus of the centerline of the follower • Pitch curve – locus of the centerline of the follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Cam Terminology • Base circle (Rb) – smallest circle that can be drawn tangent to the physical cam surface • Prime circle (Rp) – smallest circle that can be drawn tangent to the locus of the centerline of the follower • Pitch curve – locus of the centerline of the follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Cam Terminology • Base circle (Rb) – smallest circle that can be drawn tangent to the physical cam surface • Prime circle (Rp) – smallest circle that can be drawn tangent to the locus of the centerline of the follower • Pitch curve – locus of the centerline of the follower Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Cam Terminology • Base circle (Rb) – smallest circle that can be drawn tangent to the physical cam surface • Prime circle (Rp) – smallest circle that can be drawn tangent to the locus of the centerline of the follower • Pitch curve – locus of the centerline of the follower Prof. Mannoj Paul (Kinematics of Machinery)

Cam Pressure Angle • Pressure Angle ( ) • the angle between the direction of motion (velocity) of the follower and the direction of the axis of transmission • Want <30 for translating and <35 for oscillating followers Prof. Mannoj Paul (Kinematics of Machinery)

Rizvi College of Engineering Cam Eccentricity • Eccentricty ( ) – the perpendicular distance between the follower’s axis of motion and the center of the cam • Aligned follower: =0 Prof. Mannoj Paul (Kinematics of Machinery) b

Rizvi College of Engineering Overturning Moment F o r flat faced follower, hep t ressure angle is zero T h e r e is a moment on heftollower since the force is not aligned with the direction of follower motion. This is called the overturning moment Prof. Mannoj Paul (Kinematics of Machinery)

Radius of Curvature • Every point on the cam has an associated radius of curvature • If the radius of curvature is smaller than the radius of the follower doesn’t move properly • Rule of thumb: min =(2 3) x Rf Prof. Mannoj Paul (Kinematics of

Rizvi College of Engineering Cam Manufacturing Considerations • Medium to high carbon steels, or cast ductile iron • Milled or ground • Heat treated for hardness (Rockwell HRC 50 -55) • CNCmachines often use linear interpolation (larger accelerations) Prof. Mannoj Paul (Kinematics of

Rizvi College of Engineering CAMS SHAPES FOLLWER MOVEMENT Prof. Mannoj Paul (Kinematics of Machinery) CONSTRAINT MANNER

Rizvi College of Engineering CAMS SHAPES • • FOLLWER MOVEMENT WEDGES AND FLAT CAMS RADIAL OR DISC CAMS SPIRAL CAMS CYLINDRICAL CAMS CONJUGATE CAMS GLOBOIDAL CAMS SPHERICAL CAMS Prof. Mannoj Paul (Kinematics of Machinery) CONSTRAINT MANNER

Rizvi College of Engineering CAMS SHAPES FOLLWER MOVEMENT CONSTRAINT MANNER • RISE – RETURN – RISE (R-R-R) • DWELL – RISE – RETURN – DWELL (D-R-R-D) • DWELL – RISE – DWELL - RETURN – DWELL (D-D-R-R-D) Prof. Mannoj Paul (Kinematics of

Rizvi College of Engineering CAMS SHAPES FOLLWER MOVEMENT CONSTRAINT MANNER • PRE – LOADED SPRING CAM • POSITIVE – DRIVEN CAM • GRAVITY CAM Prof. Mannoj Paul (Kinematics of Machinery)