CAD CAM 2009 November

Code No: N0302 Set No. 1

IV B.Tech I Semester Regular Examinations, November 2009CAD-CAM

( Common to Mechanical Engineering, Metallurgy & Material Technology,Production Engineering and Aeronautical Engineering)

Time: 3 hours Max Marks: 80Answer any FIVE Questions

All Questions carry equal marks? ? ? ? ?

1. What is a 21/2 D model? Sketch some examples. [16]

2. Given three points P1, P2 and P3 that belong to a geometric model and given threeother points Q1, Q2 and Q3 find the transformation matrix [T] that:

(a) Transforms P1 to Q1

(b) Transforms the direction of the vector (P2- P1) into the direction of the vector(Q2- Q1)

(c) Transforms the plane of the three points P1, P2 and P3 into the plane of Q1,Q2 and Q3. [16]

3. The figure 3 shows six points.

Figure 3

(a) Find the equation of the Bezier surface defined by the six data points. Usethe u and v directions shown. Find the surface tangent and normal vectors atpoint u = 0.5 and v = 0.5.

(b) Find the two quadratic Bezier curves that bound the Bezier surface. Findthe equation of the ruled surface that uses the two curves as its rails. Is itidentical to Bezier surface? [16]

4. Three point sets in E2 define three valid polygonal solids S1, S2 and S3. The threesolids are bounded by three boundary sets bS 1, bS2 and bS3 given by their comerpoints as: bS1 := {(2, 2), (5, 2), (5, 5), (2, 5)}, bS2 = {(3, 3), (7, 3), (7, 6), (3, 6)} andbS3 = {(4, 1), (6, 1), (6, 4), (4, 4)}. Find S1 ∪ S2 ∪ S3, S1 ∩ S2 ∩ S3 and S1 - S2 - S3.

[16]

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5. (a) An end milling operation is performed on an NC machining center. The totallength of travel is 625 mm along a straight line path to cut a particular workpiece. Cutting speed = 2.0 m/sec and chip load (feed/tooth) = 0.075 mm.The end milling cutter has two teeth and its diameter = 15.0 mm. Determinethe feed rate and time to complete the cut.

(b) Write the NC manual part programming to reduce the diameter of componentfrom 40mm to 30mm over a length of 40mm. Assume suitable data. [8+8]

6. Apply the rank order clustering technique to the following part-incidence matrix togroup parts into part families. Minimum duplication of machines is allowed. [16]

Machines PartsA B C D E F G H I

1 1 1 1 12 1 13 1 1 14 1 1 15 1 16 1 17 1 1 1

7. What is meant by AS/RS? How is it implemented in FMS? [16]

8. Discuss the various network topologies used in CIM. Explain their relative advan-tages and disadvantages. [16]

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1. (a) Specify a digitizer for the CAD application and justify your choice

(b) What are the various constructional methods employed in the making of adigitizer? [16]

2. A square with an edge length of 15 units is located in the origin with one of theedge at an angle of 300 with the +X axis. Calculate the new position of the squareif it is rotated about Z axis by an angle 300 in the clockwise direction. [16]

3. The figure 3 shows four points.

Figure 3

(a) Find the equation of the Bezier surface defined by the four data points. Usethe u and v directions shown. Find the surface tangent and normal vectors.Are they constant? What is your conclusion?

(b) Using the same data points, find the equation of the ruled surface. Is itidentical to Bezier surface. [16]

4. Three point sets in E2 define three valid polygonal solids S1, S2 and S3. The threesolids are bounded by three boundary sets bS 1, bS2 and bS3 given by their comerpoints as: bS1 := {(2, 2), (5, 2), (5, 5), (2, 5)}, bS2 = {(3, 3), (7, 3), (7, 6), (3, 6)} andbS3 = {(4, 1), (6, 1), (6, 4), (4, 4)}. Find S1 ∪ S2 ∪ S3, S1 ∩ S2 ∩ S3 and S1 - S2 - S3.

[16]

5. (a) What is meant by numerical control of machine tools? Explain.

(b) List the nature of jobs that are suitable for NC manufacturing. [8+8]

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6. Four machines used to produce a family of parts are to be arranged into a GT cell.The From-To data for the parts processed by the machines are shown in the Tablebelow.

(a) Determine the most logical sequence of machines for this data using HollierMethod .

(b) Construct the flow diagram for the data, showing where and how many partsenter and exit the system,

(c) Compute the percentage of in-sequence moves and the percentage of back-tracking moves in the solution.

(d) Develop a feasible layout plan for the cell. [16]

From To1 2 3 4

1 0 10 0 402 0 0 0 03 50 0 0 204 0 50 0 0

7. A flexible machining system consists of two machining workstations and a load/unloadstation. Station 1 is the load/unload station. Station 2 performs milling operationsand consists of two servers (two identical CNC milling machines). Station 3 hasone server that performs drilling (one CNC drill press). The stations are connectedby a part handling system that has four work carriers. The mean transport timeis 3.0 min. The FMS produces two parts. A and B. The part mix fractions andprocess routings for the two parts are presented in the table below. Compute theproduction rate, manufacturing time and waiting time when the number of unitsin the system is 4. [16]

Part Part Mix Operation Description Station Process time (min)A 04. 1 Load 1 4

2 Mill 2 303 Drill 3 104 Unload 4 2

B 0.6 1 Load 1 42 Mill 2 403 Drill 3 154 Unload 1 2

8. Discuss the various network topologies used in CIM. Explain their relative advan-tages and disadvantages. [16]

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1. A 60 Hz non interlaced colour display terminal has a resolution of 1024 horizontalx 768 vertical pixels with the ability to display 256 colours simultaneously. Find:

(a) The RAM size of the bit map (frame buffer)

(b) The time required to display a scan line and a pixel.

(c) The optimal resolution design if the bit map size is to be reduced by half. [16]

2. Show that

(a) Translation is commutative.

(b) Mirror and 2D rotation about the Z axis are not commutative.

(c) Scaling and 2D rotation about the Z axis are commutative. [16]

3. Find the condition that degenerates a cubic Bezier curve to a line connecting P0

and P3. Derive a method by which you can force a Bezier curve to pass through agiven point in addition to the starting and end points of its polygon. Achieve thatby changing the position of only one control point, say P2. [16]

4. What information do you need to define a coordinate system? Why do CAD/CAMsystems allow you to define a coordinate system (i.e., what is the use of it)? Providean example. [16]

5. The part in the following figure 5 is to be drilled on a turret-type drill press. Thepart is 15.0 mm thick. There are three drill sizes to be used: 8 mm, 10 mm, and 12mm. These drills are to be specified in the part program by tool turret positionsT01,T02, and T03. All tooling is high-speed steel. Cutting speed = 75 mm/minand feed = 0.08 mm/rev. Use the lower left corner of the part as the origin inthe x-y axis system. Write the NC part program. Use absolute positioning. Alldimensions are given in mm. [16]

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Figure 5

6. (a) What is meant by a part family in GT? What is the need of grouping partsinto part families?

(b) What are the differences between Design attributes and Manufacturing at-tributes? [8+8]

7. Describe the following operational issues related to FMS.

(a) Scheduling and dispatching

(b) Machine loading. [8+8]

8. Describe the role of Manufacturing Automation Protocol (MAP) in integrating thevarious programmable devices in CIM. [16]

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1. A 60 Hz non interlaced colour display terminal has a resolution of 1024 horizontalx 768 vertical pixels with the ability to display 256 colours simultaneously. Find:

(a) The RAM size of the bit map (frame buffer)

(b) The time required to display a scan line and a pixel.

(c) The optimal resolution design if the bit map size is to be reduced by half. [16]

2. Show that

(a) Translation is commutative.

(b) Mirror and 2D rotation about the Z axis are not commutative.

(c) Scaling and 2D rotation about the Z axis are commutative. [16]

3. Find the equation of an open quadratic B-spline curve defined by five control points.[16]

4. Explain linear, diameteral, radial and angular dimensioning in AutoCAD with aneat sketch. [16]

5. (a) Explain the working of BTR type of interface used in DNC?

(b) What are the differences between CNC and DNC? [8+8]

6. Explain the Retrieval CAPP with an example. What are its relative advantageswhen compared to the Generative CAPP? [16]

7. Describe the various methods of work and tool probing in FMS. What are itsbenefits? [16]

8. Describe the role of Manufacturing Automation Protocol (MAP) in integrating thevarious programmable devices in CIM. [16]

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