MEGHANICAL ENGINEERING, PAPER- I – 2003, SECTION B

                     Time Allowed: three Hours                  Maximum Marks: 200

Candidates should attempt Questions 1 and 5 which are compulsory, and any THREE of the remaining questions selecting at least ONE question from each Section. Assume suitable data, if considered necessary, and indicate the same clearly. Newton may be converted to kg using the relation 1 kilonewton (1 kN) = 100 kg if found necessary.    

SECTION B

5.       Answer any  four of the following (each answer should conform to a limit of around 150 words)
                  (a)    (i) Explain the differences between tolerance and allowance.

(ii) Discuss the terms ‘roughness’ weaviness’ and ‘lay’

(b)   (i) Why is springback important in cold forming?

(ii) Why most press forging often employ heated dies?

(iii) What is 3-2-1 concept related to jig and fixture design?

(c)    (i) What are various types of valve? What do you personally gain from value engineering?

(ii) Give some examples of waiting time situations existing in industry.

(d)   (i) Draw figure showing four waiting line structures.

(ii) What types of distributions are assumed for arrivals and services?

(iii) In a single channel waiting line if μ = λ, what will be the utilization factor and mean waiting time for a customes before being served μ = Av. No. of services provided per unit time and λ = Av. No. of arrivals per unit time.

                    (e)   (i) Write the purpose of subroutine in a computer program including its general form.

(ii) Name three types of plotters used in computers to produce hard copy.

6.       (a) (i) write the circuits which make control loop unit (CLU) in CNC machine

(ii) What is meant by the following codes?

g 9 0

m 0 3

      (b)  DC servomotor is coupled directly to a lead screw which drives the table of an NC machine tool. A digital encoder, which emits 500 pulses per revolution, is mounted on the other end of the lead screw. If the lead screw pitch is 5 mm and motor rotates at 800 rpm calculate.

(i)                  The linear velocity of the table

(ii)                The basic length unit (BLU) of the N.C system

(iii)               The frequency of the pulses transmitted by the encoder. 1 pulse = 1 BLU.

        (c)   (i) Explain with a figure stylus profile device for measuring surface roughness.

                    (ii) How Ra (arithmetic mean) value of surface roughness is defined.

7.       (a) Florence Health INC is a Professional II nursing home aspiring to become Professional I nursing home. Administrator prepares the following list of activities:

Activity	Predecessor’s Activity	Time estimates  (Weeks)
		to	tm	tp
B. Build Facility	None	20	24	30
F. Safety Inspection	B	2	3	4
C. Install Equipment	B	8	16	20
D.Recruit Staff	None	2	2	3
E. Train Staff	D	4	5	6
A. Perform Pilot	C. E. F	6	5	9

Draw the PERT diagram and show the critical path (consider β- distribution) what is Time / Cost tradeoff?
           (b) Solve the assignment problem represented by the matrix given below:

	a	b	c	d	e	F
A	9	22	58	11	19	27
B	43	78	72	50	63	48
C	41	28	91	37	45	33
D	74	42	27	49	39	32
E	36	11	57	22	25	18
F	3	56	53	31	17	28

8.       (a) (i) Discuss the principles and applications of slip gauges. What are the different grades of accurac
            (ii)  Draw Merchant’s circular force diagram and write the assumptions.

       (b) Solve the following linear programming problem:

Maximize      z= 3x₁ + 2x₂ + 5x₃

Subject to

X₁ + 2X₂   + X₃ ≤ 430

3X₁ + 2X₃ ≤ 460

X₁ + X₂ ≤ 420

X₁ ≥ 0, X₂ ≥ 0, X₃ ≥ 0.