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# Andhra University 2009-8th Sem B.B.M - Question Paper

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Eighth Semester B.Tech. Degree Examination, November 2008
(2003 Scheme)
Branch : Production
03.804 : MACHINE TOOL DESIGN (P)
Time : three Hours Max. Marks : 100
Instructions: 1) ans all ques. from Part A.
2) ans 1 ques. from every Module in Part B.
3) Use of approved design data book permitted.
4) presume suitable data wherever necessary.
PART – A
1. Why geometric progression is used for spindle speeds ?
2. discuss the significance of Petroff's formula in bearing design.
3. elaborate the factors governing the design of Ball and Roller bearings ?
4. List out the important physical characteristics of a good bearing material.
5. When do we prefer herringbone gears over spur and helical gears ?
6. elaborate the advantages of helical gears over spur gears ?
7. What is meant by interference in gears ? How it will be overcome ?
8. Why a combination of flat and V kind slideways is preferred for machine tools ?
9. elaborate the basic requirements of a machine tool ?
10. discuss the significance of speed diagrams in machine tool design.
(10×4=40 Marks)
Reg. No. : .....................................
Name : ..........................................
P.T.O.
7116 -2- ______
PART – B
Module – I
11. Design a bearing and journal to support a load of 4500 N at 600 rpm using a
hardened steel journal and a bronze backed babbit bearing. An abundance of oil is
supplied by means of oiling rings. The oil viscosity is 250 2nd saybolt at 37.8°C
and the specific gravity is 0.90 at 15.6°C. The bearing is relieved for 20 degree
from the normal to the load line. 20
12. A ball bearing operates on the subsequent work cycle.
Element No.
Speed (rpm) Element time (%)
1 3000 720 30
2 7000 1440 50
3 5000 900 20
The dynamic load carrying capacity of the bearing is 16.6 kN. obtain
a) The avg. speed of rotation.
c) The bearing life. 20
Module – II
13. A pair of spur gears is to be used for a sugar crusher. Design the gears for strength.
Power transmitted = 25 kW
Speed of pinion = 400 rpm
Speed reduction ratio = 4:1
Tooth profile = 20° full depth involute
Velocity = six m/sec (limited). 20
______ -3- 7116
14. Design a worm gear drive to transmit three KW at 600 rpm. Speed of worm wheel is
40 rpm. Tabulate the outcomes neatly. 20
Module – III
15. discuss with sketches the various kinds of machine tool beds and their design
features. 20
16. a) provide an account about design of slide ways for wear resistance. 10
b) Enumerate the basic procedure associated with Ram-type structures. 10

Eighth Semester B.Tech. Degree Examination, November 2008

(2003 Scheme)

Branch : Production

03.804 : MACHINE TOOL DESIGN (P)

Time : 3 Hours Max. Marks : 100

Instructions: 1) Answer all questions from Part A.

2) Answer one question from each Module in Part B.

3) Use of approved design data book permitted.

4) Assume suitable data wherever necessary.

PART A

1. Why geometric progression is used for spindle speeds ?

2. Explain the significance of Petroffs equation in bearing design.

3. What are the factors governing the design of Ball and Roller bearings ?

4. List out the important physical characteristics of a good bearing material.

5. When do we prefer herringbone gears over spur and helical gears ?

6. What are the advantages of helical gears over spur gears ?

7. What is meant by interference in gears ? How it will be overcome ?

8. Why a combination of flat and V type slideways is preferred for machine tools ?

9. What are the basic requirements of a machine tool ?

10. Explain the significance of speed diagrams in machine tool design.

(104=40 Marks)

Reg. No. : .....................................

Name : ..........................................

P.T.O.

7116 -2- ______

PART B

Module I

11. Design a bearing and journal to support a load of 4500 N at 600 rpm using a

hardened steel journal and a bronze backed babbit bearing. An abundance of oil is

supplied by means of oiling rings. The oil viscosity is 250 Second saybolt at 37.8C

and the specific gravity is 0.90 at 15.6C. The bearing is relieved for 20 degree

from the normal to the load line. 20

12. A ball bearing operates on the following work cycle.

Element No.

Speed (rpm) Element time (%)

1 3000 720 30

2 7000 1440 50

3 5000 900 20

The dynamic load carrying capacity of the bearing is 16.6 kN. Find

a) The average speed of rotation.

c) The bearing life. 20

Module II

13. A pair of spur gears is to be used for a sugar crusher. Design the gears for strength.

Power transmitted = 25 kW

Speed of pinion = 400 rpm

Speed reduction ratio = 4:1

Tooth profile = 20 full depth involute

Velocity = 6 m/sec (limited). 20

______ -3- 7116

14. Design a worm gear drive to transmit 3 KW at 600 rpm. Speed of worm wheel is

40 rpm. Tabulate the results neatly. 20

Module III

15. Explain with sketches the different types of machine tool beds and their design

features. 20

16. a) Give an account about design of slide ways for wear resistance. 10

b) Enumerate the basic procedure associated with Ram-type structures. 10

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