Question

A disc cam is to give SHM (Simple Harmonic Motion) to a knife-edge follower during outstroke of 50mm. The angle ascent is 120, dwell 60, and angle of descent 90°. The minimum radius of the cam is 50mm. Draw the profile of the cam when the axis of the follower passes through the axis of the camshaft. Calculate the maximum velocity and acceleration during ascent and descent when the camshaft revolves at 240 rpm.

Answer 1

Scale for Displacement diagram

X Axis : 1 Cm = 20°

Y Axis : 1 Cm = 1 m

Steps for drawing is given in attachment.

* Given dara h = som scale: YayS: 10m = 20 YAXIS: 10m = 1m ©2 = 120* (SHM) 02= Goº (DWC) @z = goº (SHM) Ona go (Dwell) [:3602 (120+60+93) = 90') R = 50mm 6' PG PS 81 P4 g' Pg 3! B so" Pio h: 50m 190 21 11' PAL P2 Po 1' 12 2 (P12 P13 8 9 10 11 12 13 Riu 3 4 S 6 7 74 O = 120 •O3 =go (2 Make -0,=60- 04=90° — Method:- Displacement Dicgeam © First decide scale for x x y Axis . (x Ayis is for crank angle & Y Avis is for skoke) so draw 18cm x 5 cm Rectangle box as per given scale. Cx Avis: 340 = 18 cm, Y Avis 50m - soom) Devide rectangle into the the 4 box crccos ding to the CQ, O2, O3 404). a equal divisions on horizontal line in a & Oz. And deciw vertical lines from the divisions. (we have make 6 divisions). Druw semi circle on left side of Rectangle for simple Hasmonic Motion. And deride the cingle included by semi ciele (180) into the same divisions which you have plot on horizontal line! (Hele it is 6 divisions, Each aigle = Draw lines from divisions of semi cirde. And mark a horizontal parallel lines Inter section point (P1, P2, P3 PIL is called profil point for cam. And give dimensions at every ahore. 180 6 $0 = 30 16

1 ܠܠܠܠܠܠ knief edge followers 1P1 APIG 0/14 cam profile P3 Steps: Drew Buse circle of R- somm ② Devide that carek in to 4 parks @,,02,03806) Make equel divisions in ork ©g, same as the displacement diagram. 4 Make a arc 1 top, , 2 to P2 12 to Pt2 on equal divisims. Cake Distance psom Displacement Di coscim) Dreuw smooth curve from Pe. P2 B..... Piz. which is called cam profile PG O=x28 04 90° 5 IPB 13 Po * O2 = 60 Piel 12 0 Pul PG g 7 CHO Base circle Rd Pg B