Thapar University 2006 B.E Mechanical Engineering Computer Aided Manufacturing - Question Paper
Thapar Institute Of Engineering & Technology, Patiala
End Semester Examination, 2006
Computer Aided Manufacturing (ME 018)
, End Semester Exam I' '
Sub: Computer Aided Manufacturing (ME 018)
B.E. Final Year. Mechanical, Date: 13/12/2006
Instructions:
Attempt Question I and any 5 from the rest Time: 3 Hours
All questions carry equal marks Instructor: T. Chakraborty
Use graph paper for question no 6(a)
Answer for a particular question should be at one place Assume suitable data wherever necessary
t. (i) Under what circumstances are closed loop NCs used? Give example.
(ii) Justify the use of *Ruby* as probe tip inCMM.
(iii) What situation warrants the use of * paint strips \ in vehicle guidance technology in AGVs?
(iv) SCARA robot doesnt come with a separate wrist assembly- Give reason.
(v) What do you mean by APT Major and APT Minor words? Give example.
(vi) Why retrieval type CAPP is also known as variant type CAPP? [6*1]
2. (a) .Write a short note on CODE system used in part classification and coding. [3] (b) Give an example each for 'fixed', \flexible and programmable automation [1.5]
(b) With a neat sketch show the various modes of approximation of a curved path done by a NC system. [ 1.5]
3. (a) A component has to be machined as shown below. The upper profile needs to be machined using an end
mill cutter of diameter <J>16mm. Two holes on the finished surface needs to be drilled with a <D8mm drill. The path to be taken by the tool to generate the profile is shown as centerline. Write the complete part program without using radius compensation and drilling canned cycles. Clearly show the axes and the set point. [4+1]
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2 Holes 8* |
(b) Categorize the following APT statements: OUTTOL, MACHIN, LOADTL, FINI
[1]
4. (a) Illustrate with a neat sketch the tool change procedure with a double gripper tool change arm in an ATC.
(b) FMS milling and drilling technology is more mature than FMS turning - Discuss [1.5]
(c) Mention the most suitable robot configuration for the following:
(i)Placing a component in a CNC machine tool, (ii) picking a part from a moving conveyor, (iii) placing an object in an oven for heat treatment, (iv) welding a steel almirah, (v) inserting a peg into a hole. [2.5]
5. (a) State with reason whether the following are permissible symbols or not in APT geometry statement:
(i)PA2CD9F (ii) 135246 (iii) CIRCLE (iv) P1.5 [1]
(b) A stepper motor with 200 step angles is coupled to lead screw through a gear reduction of 5:1(5 rotations of motor for each rotation of lead screw). The lead screw has 2.4 threads/cm. the worktable driven by the lead screw must move a distance = 25 cm at a feed rate of 75cm/min. determine (a) number of pulses required to move the table (b) the required motor speed and (c) the pulse rate to achieve the desired table speed. [3]
(c) With the aid of a neat sketch, describe briefly the pitch\ 'yaw' and *roll motion of a robot wrist. [2]
6. (a) The following APT statements gives complete geometry of a part
PARTNO SAMPLE PART MILLING OPERATION
MACHIN/M1LLING, 01
UNITS/MM
REMARK Part geometry
PINPOINT/ 40, (160+40- 10) r
P2= POINT/40,40 Ll=LINE/Pl,P2 L5=LINE/XAXIS
L4=LINE/PARLEL, L5, YLARGE, 40 L2=LINE/PARLEL, L4, YLARGE, 160 L3=LINE/ (POINT/ (40+120), (40+160)), ATANGL, 135 C2=CIRCLE/ YLARGE, L4, XSMALL, L3, RADIUS, 20 A= SQRT (40*40-30*30)
Cl CIRCLE/(40+A), 160,40 FIN I
Using a graph paper draw the entire part with proper dimensions to the scale. [4.5]
(b) Differentiate between an AS/RS and a carousel in terms of storage structure, motion and storage retrieval operation. [1.5]
7. (a) The length of one aisle in an AS/RS is 100m and its height is 20m. Horizontal travel speed is 2 m/sec. the
vertical speed is so specified that the storage structure is square in time (i.e. L/Vy =H/V1). The pick up and deposit time is 15 sec. Determine the expected transactions per hour for the aisle if the ratio of single to dual command cycles is 2 :1. The system operates continuously during the hour. [3]
(b) Explain the term "fixedzero' and 'floating zero in context of NC. [2]
(c) With an example, differentiate between GOTO and GODLTA command in APT. [1]
8. (a) Three point locations on the surface of a drilled hole have been measured by a CMM in the X-Y axes. The three coordinates are (34.41, 21.07), (55.19, 30.50) and (50.10,13.18) mm. The given coordinates have been corrected for probe radius. Determine (a) coordinates of the hole center (b) hole diameter as they would be computed by the CMM software. [4.5}
(b) Differentiate between an FMS and an FMC. [1.5]
NB: The evaluated answer scripts.will be available for viewing at the course instructors office (S.M Lab) on 15tb December 2006, between 9:30 AM -12:00 PM
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| Earning: Approval pending. |
