# chap05 - 67 PART II DESIGN OF MECHANISMS 68 [Page...

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Unformatted text preview: 67 PART II DESIGN OF MECHANISMS 68 [Page intentionally blank.] 69 Chapter 5 Cam Design 5.1 The reciprocating radial roller follower of a plate cam is to rise 2 in with simple harmonic motion in 180 o of cam rotation and return with simple harmonic motion in the remaining 180 ° . If the roller radius is 0.375 in and the prime-circle radius is 2 in, construct the displacement diagram, the pitch curve, and the cam profile for clockwise cam rotation. 5.2 A plate cam with a reciprocating flat-face follower has the same motion as in Problem 5.1. The prime-circle radius is 2 in, and the cam rotates counterclockwise. Construct the displacement diagram and the cam profile, offsetting the follower stem by 0.75 in in the direction that reduces the bending stress in the follower during rise. 5.3 Construct the displacement diagram and the cam profile for a plate cam with an oscillating radial flat- 70 face follower that rises through 30 ° with cycloidal motion in 150 ° of counterclockwise cam rotation, then dwells for 30 o , returns with cycloidal motion in 120 ° , and dwells for 60 ° . Determine the necessary length for the follower face, allowing 5 mm clearance at each end. The prime-circle radius is 30 mm, and the follower pivot is 120 mm to the right. Notice that, with the prime circle radius given, the cam is undercut and the follower will not reach positions 7 and 8. The follower face length shown is 200 mm but can be made as short as 195 mm (position 9)from the follower pivot. Ans. 71 5.4 A plate cam with an oscillating roller follower is to produce the same motion as in Problem 5.3. The prime-circle radius is 60 mm, the roller radius is 10 mm, the length of the follower is 100 mm, and it is pivoted at 125 mm to the left of the cam rotation axis. The cam rotation is clockwise. Determine the maximum pressure angle. From a graphical analysis, max 39 ϕ = ° Ans. 5.5 For a full-rise simple harmonic motion, write the equations for the velocity and the jerk at the midpoint of the motion. Also, determine the acceleration at the beginning and the end of the motion. Using Eqs. (5.18) we find 1 sin 2 2 2 2 L L y θ π π π β β β ′ = = = ÷ Ans. 3 3 3 3 1 sin 2 2 2 2 L L y θ π π π β β β ′′′ = = - = - ÷ Ans. 2 2 2 2 cos0 2 2 L L y θ π π β β β ′′ = = = ÷ Ans. 2 2 2 2 1 cos 2 2 L L y θ π π π β β β ′′ = = = - ÷ Ans. 72 5.6 For a full-rise cycloidal motion, determine the values of θ for which the acceleration is maximum and minimum. What is the formula for the acceleration at these points? Find the equations for the velocity and the jerk at the midpoint of the motion....
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## This note was uploaded on 04/03/2012 for the course MECHATRONI 111 taught by Professor Jung during the Spring '11 term at Hanyang University.

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chap05 - 67 PART II DESIGN OF MECHANISMS 68 [Page...

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