MACHINE DESIGN 2 PAPER

DOWNLOAD MECHANICAL ENGINEERING PREVIOUS YEARS QUESTION PAPERS PTU B.TECH

MACHINE DESIGN II 6th Semester (ME 302) Dec. 2006

Note: Question No. 1 carrying 20 marks is compulsory. Attempt any four questions from Section B and any two from Section C
Section A 2 marks each

I

1. Chain drives are not suitable for timing applications, why?
2. Specify the conditions which must be satisfied for the hydrodynamic lubrication to be possible.
3. Enlist approximate values of efficiencies of worm drive with different number of starts.
4. In a fly wheel, the major axis of the elliptical section of the arm is in the plane of rotation. Write down the reason for this arrangement.
5. Design of a disc clutch is based on uniform wear condition. Why?
6. What do you mean by ‘Surge’ in springs?
7. Sketch a 6 x 19 wire rope and name its parts.
8. What does morphology mean when applied to CAD process?
9. What is 3D CAD?
10. What is the general structure of CAD software?

Section B 5 marks each

II A v-belt drive transmits 25 hp from a 250 mm diameter v-pulley operating at 1800 r.p.m. to a 900 mm diameter pulley. The centre distance is 1 m and the groove angle is 40 o. Take  = 0.2. If the weight of the belt is 0.01 N/cm2 and allowable stress is 2 N/mm2 for belt material, what will be the number of belts required if C-size v belts having 2.3 cm2 cross-sectional area are used?

III A band brake has to absorb 4.5 kW at 150 r.p.m. For long life, the maximum pressure between band and drum is 0.7 MPa. The width of band is 50 mm and  = 0.12. Find the angle of wrap if the brake drum diameter is 300 mm.

IV A punching press pierces 35 holes per minute in a plate using 10 kN-m of energy per hole during each revolution. Each piercing takes 40% of the time needed to make one revolution. If the motor efficiency is 80%, find the fluctuation of energy.

V Discuss the roles of computers in design process.

VI Write short note on the lubrication in the gear transmission system.

Section C 10 marks each

VII A compressor running at 250 r.p.m. is driven by a 15 kW 870 r.p.m. motor through a 14 ½ o full depth spur gears. Estimate he module, the beam width and number of teeth on each gear. Assume suitable materials for pinion and gear. Sketch the teeth.

VIII A compressor spring is required to exert a minimum force of 250 N and maximum force of 600 N. The deflection for this change of load is to be 15 mm. The spring must be fit in a hole of 300 mm diameter. The load is essentially static. Design appropriate spring and sketch the same.

IX Design a journal bearing for a centrifugal pump. The load on the bearing is 3.5 kN and the journal diameter is 75 mm. The shaft runs at 900 r.p.m. The ambient temperature may be taken as 25 oC.