Question

Consider a cam with a roller follower. The cam displacement curve is in the given order: i. for 45 degrees, a sinusoidal rise of 1 in ii. for 75 degrees, a dwell iii. for 60 degrees, a cycloidal return of 1 in iv. for 180 degrees, a dwell During the motion, the velocity is continuous but not necessarily the acceleration. a) Assume a constant cam speed of 1200 rpm. Find the maximum magnitude of the velocity (in inch/s) and acceleration (in inch/s) of the follower during rise and return. The radius of the roller is 0.5 in and the minimum radius of the pitch surface is 2.5 in. b) Determine the maximum pressure angle c) Will the cam be pointed or undercut? P.S. The questions of this problem are mainly independent.

Answer 1

The linear velocity and acceleration have been calculated from the general laws of motion. As the angular speed remains the same and the follower has to scale an additional height of 1" due to sinusoidal rise, it will cause an increase in velocity.

Com pre Nene fer Pre Ore Fel Ro Rodius of can Car of a base disabi (ai at ,20 pm w 1,200 20x20 n a uon rad & This will remain the same. max rudius at the interface 25" (for base radices of cam + 1rese a 35 Voleil, vow yon) 8.5° - 439.823 in/ser. acrelation, a whor (400) 3.5 • X2 (439 823)2 35 8,164 inis (6) (6) Max promure angle a 15", from the admetread construction This will be a pointed cam.

The normal to the pitch curve will intersect the end of dwell period at 90 deg (as shown); hence, the max. pressure angle will be 15 deg.