TOM Lab Project Anshul Padyal -120103016 Anmol Mukati – 120103014 Submitted By: Ankit Soni – 120103012 Anshul Padyal -120103016 Anmol Mukati – 120103014 Anurag Sao -102103018

New experiment suggestion JUMP-OFF SPEED OF CAM FOLLOWER

Where we can see cam-follower mechanism In IC engine

introduction Cam is a rotating machine element which gives reciprocating or oscillating motions to another element known as follower

continued Cam and follower are widely used in regulating, opening and closing of valves (inlet and exhaust) in the internal combustion engines. Proper design of cam and follower is required for perfect tuning between opening and closing of valves with cam shaft speed. For a proper design follower should always remain contact with cam, but in reality this contact remain up to a certain angular speed (critical speed) and beyond that the follower jump off the cam and design will fail.

Aim of the experiment To obtain displacement diagram and cam profile for various type of cam follower system and spring forces. To determine the “jumping speed” for different type of cam follower and speed. To determine contact forces and torque variation on cam according to the cam rotation angle. Compare all data with calculated values.

Apparatus Specifications Set up: NIT Trichy

Apparatus Specifications (continued) The unit consists of a cam profile and study of cam follower system. The instrument consists of cam mounted shaft supported by ball bearing upon which three different type of cam can be mounted. Motor rotates the cam and dial gauge is provided for plotting of follower displacement W.R.T. cam position. Cam jump speed can be found by operating different speed and effect of speed and spring force on jump speed can also be studied.

Apparatus Specifications (continued) Components:- Cam :Eccentric, tangent, circular. Follower-Knife edge, roller type & mushroom type. Variable speed motor coupled to cam shaft of suitable range and various speeds. A dial gauge. Service Required:- 230V A.C. supply Bench area of 0.5 m x 1 m at working

Range Of Experiments: Plotting and analysis of the X- Θ curve. Velocity, acceleration and jump off speed can be found by all these curves. To study the effect of follower weights (W) on the speed of bounce. To study the effect of initial spring compression (S) on the peed of bounce. Test can be repeated by changing parameters like various compression springs ,follower weights and cam speed.

Observations table Angle Of Rotation Of Cam Displacement Of Follower Velocity Of Follower Acceleration Of Follower Setup can be purchased from Super Tech Equipments Sangli, Maharashtra

Theory

Theory(continued) 1. Cycloidal Motion:- Equations for various governing motions of follower 1. Cycloidal Motion:- y = h[(θ/β) –(1/ 2п) * sin(2пθ/β)] 2. Simple Harmonic Motion:- y = (h / 2)*[1- cos(пθ/β)] 3. Constant Velocity:- y = hθ/β Where, h = Lift of the follower, θ = Angular displacement of cam, β = Angle of rise, y = vertical displacement of follower

Theory(continued) DYNAMIC ANALYSIS:- F23y = Fs + (—mŸ) --------(1) Where, Ÿ = Acceleration of the follower, F23y = Reaction of link 2 on link3 m = Mass of follower Fs = Spring force, Suppose choose harmonic motion of follower- y = (h / 2)*[1- cos(пθ/β)] assume; θ’ = пθ/β y = (h / 2)*[1- cos(θ’)]

Theory(continued) diff. equation Y’ = (h/2)* sin(θ’) * ώ again diff. equation assume constant ώ Ÿ = (h/2)* cos(θ’) * ώ2 Put in equation eq(1) >> F23y = — k*Y — m*(h/2)* cos(θ’) * ώ2 >> F23y = — k*(h / 2)*[1- cos(θ’)] — m*(h/2)* cos(θ’) * ώ2 >> F23y = (h/2)* [(k — m ώ2)*cos(θ’) — k ] >> F32y = (h/2)* [(m ώ2 — k)*cos(θ’) + k ] -----(2)

Theory(continued) contact force is maximum when θ’ = 0° and minimum when θ’=180°.This force when less than zero would result in the follower loosing contact with the surface, resulting in jump. This would happen, if the speed is increased beyond a particular critical speed ώcr and when the cam is at θ’=180° Substituting, in eq (2)

Theory(continued) >> 0 = (h/2)* [(m ώ2 — k)*(-1)+ k ] >> F32y = (h/2)* [(m ώ2 — k)*cos(θ’) + k ] >> 0 = (h/2)* [(m ώ2 — k)*(-1)+ k ] >> ώcr = √2k/m >> ωcr = п ώcr/β >> Critical speed ωcr = (п /β)* √2k/m

Expected Conclusion There are variations in jumping speed by experimentally, analytically and simulation model. The reason behind it is that friction is not considered in analytically, and simulation model whereas friction is considered in experimental method.

Suggestion in tom lab expt. (1) In whirling of shaft experiment, actually the motor is not so efficient and wouldn't go after 1000rpm . While doing the experiment, we need 2nd mode at 2800rpm so we couldn’t do that 2nd mode experiment. so that motor should be replaced with an efficient motor so that 2nd mode can be achieved.

Suggestion in tom lab expt. In Gyroscope experiment, while rotating the gyroscope the power supply wire whirl around the gyroscope so to prevent this whirling we can replace the power system by a interconnected recharge able battery.

Suggestion in tom lab expt. In governor experiment, while measuring the displacement of top of governor with vernier caliper, the top part displaced a little bit so due to that reading can’t be taken accurately. So we can replace this vernier measurement by high proximity sensor.

reference http://www.indiamart.com/supertechequip ments/theory-machine-lab.html [4] http://www.nitt.edu/home/academics/depa rtments/mech/facilitiesandservices/dynamic slab/jumpspeed/ [5] http://www.iaeng.org/publication/WCE2010/WCE2010_pp1246-1250.pdf http://www.technicaljournalsonline.com/ijaers/VOL%20I/IJAERS%20VOL%20I%20ISSU E%20II%20JANUARY%20MARCH%202012/IJAERS%2095.pdf

Thank you