C S (Main) MECHANICAL ENGINEERING Paper I

SECTION A
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Ql. Draw a cranked-slider quick return mechanism and explain its principle with figure. 10

Explain the fundamental law of gearing with a neat sketch. 10

A circular punch, 20 mm in diameter, is used to punch a hole through a steel plate 10 mm thick. If the force necessary to drive the punch is 250 kN, determine the maximum shearing stress developed in the plate. 10

A spherical gas container made of steel has 5·4 m outer diameter and wall thickness of 10 mm. Knowing that the internal pressure is 400 kPa, determine the hoop stress and longitudinal stress in the container. 10

What are the advantages of tempering carbon steel Show with the help of iron-carbon equilibrium diagram, how low, medium and high temperature tempering are done. 10

Q2. Consider a hollow circular shaft whose outside diameter is 0·0762 m and whose inside diameter is equal to one-half the outside diameter. The shaft is subjected to twisting moment of 2259·584 N-m as welJ as bending moment of 3389·376 N-m. Determine the principal stresses. Also determine the maximum shear stress. 20

For the beam shown in Figure write the equations for the shear force and bending moment at any point. Also draw the shear force and bending moment diagrams.

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Find the centroid of the element shown in Figure
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Q3. An epicyclic gear train consists of a pinion, a wheel of 40 teeth and an annulus with 84 internal teeth concentric with the wheel. The pinion gears with the wheel and the annulus. The arm that carries the axis of
the pinion rotates at 100 rpm.
Find the speed of the wheel.
Find the speed of the annulus, if the wheel is fixed. 20

A machine of mass 20 kg is mounted on springs and dashpot as shown schematically in the Figure The total stiffness of the springs is 100 N/cm and the total damping is 1·5 N-sec-cm-1. If the system is .initially at rest and a velocity of 10 cm/sec is imparted to the mass, determine

the displacement and velocity of the mass as a function of time,
the displacement and velocity at the time equal to one second. 20
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What is the composition of maraging steel? What are its uses? Give the composition of austenitic stainless steel and state some of its applications. . 10


Q4.(a) An automobile with the distance between front and rear wheels 3·0 m and height of centre of gravity 300 mm is travelling over a roadway inclined at an angle 6 with horizontal. The coefficient of static and dynamic friction are and respectively. The automobile is a rear
wheel drive and has a load of 18 kN. What is the maximum inclination 6max that the automobile can climb at uniform speed? 20

A riveting machine is driven by a constant torque 4 kW motor. Each riveting operation takes 1 second and requires 9000 N-m of energy. A flywheel of mass 130 kg and radius of gyration 0·5 m is fitted to the riveting machine. If the speed of the flywheel is 420 rpm before riveting, find

the fall in the speed of the flywheel after riveting,
the number of rivets fitted per hour. 20

What are the advantages of annealing steel Explain the process of annealing with a sketch of Time Temperature transformation and ending with spheroidizing. 10

SECTIONB

Q5. What are the different tool wear causes that are responsible for wearing of tool Explain crater, flank and wear. 10

There are five jobs each of which must go through machines B and C in the order A B C. Processing times are as per the following table:

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Determine the sequence for the five jobs that will minimize the elapsed time. 10

Derive the relationship between tensile and shear yield stresses by applying the following:
Von-Mises criterion (Maximum distortion energy)
Tresca criterion

Discuss the advantages and limitations of 'Process Layout'.
A 20 mm diameter shaft and bearing are to be assembled with a clearance fit. The tolerance and allowances are as under:
Allowance =0·002 mm
Tolerance on hole 0·005 mm
Tolerance on shaft 0·003 mm
Find the limits of size for the hole and shaft, if
the hole basis system is used,
the shaft basis system is used.
The tolerances are disposed off unilaterally. 10

Q6. In,an orthogonal cutting operation, the tool has a rake angle 10°. The clip thickness before the cut mm and the cut yields a deformed clip thickness 1·125 mm.
Calculate
shear plane angle,
shear strain for the operation.
Derive the formulae that are to be used while finding out the shear plane angle and shear strain. 20

How is plasma arc welding different from tungsten inert gas welding Why is plasma arc welding associated with higher temperatures? With the heip of neat sketches, explain transferred and non-transferred plasma arc welding. 20

Briefly explain the different types of jigs. What do you understand by intermediate jig concept? 10

Q7. Derive an expression for Economic Order Quantity when stock replenishment is non-instantaneous (Production Model) with the following assumptions 10

I. Item is sold and consumed at the constant rate which is
known.
II. Set-up cost is constant and does not change with lot size.
III. The increase in inventory is not instantaneous but gradual.

A contractor undertakes to supply diesel engines to a truck· manufacturer at the rate of Rs.25 per day. Cost of holding a completed engine in stock is Rs.16/month. Production of engines is undertaken in batches. Each time a new batch is started, a set-up cost of Rs.10,000 is required irrespective of the number of engines produced. How frequently should the batches be started and what will be the minimum average inventory cost and production time, ifthe production rate is 40 engines/day? Assume 300 working days in a year. 10

A dairy firm has three plants located in a State. The daily milk production at each plant is as follow:
Plant 1 6 million litres
Plant 2 1 million litres
Plant 3 10 million litres

Each day, the firm must fulfil the needs of its four distribution centres.The minimum requirement of each centre is as follows
Distribution Centre 1 7 million litres
Distribution Centre 2 5 million litres
Distribution Centre 3 3 million litres
Distribution Centre 4 2 million litres
Cost (in hundreds of rupees) of shipping one million litres from each
plant to each distribution centre is given in the following table:

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Find the initial basic feasible solution for minimum total cost by
Least Cost Method, and
Vogel's Approximation Method.

Will Just-In-Time work in service requirement as well as it works in production environment Enlist the applications of JIT in service industry. 10

Q8. Use the dual simplex method to solve the following problem
Maximize: z 2xl 3x2
subject to: xl
2xl x2<_10
xl 8
with xl and x2 non-negative. 20

With the help of a neat schematic sketch explain the electrochemical machining process. Also discuss its applications. 20

Discuss the advantages and limitations of NC manufacturing process. Also enlist the advantages of CNC manufacturing over NC manufacturing process. 10