Download JNTUA M.Tech 2nd Sem 2017 Feb 9D04204 CNC And Technology Programming Question Paper

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Code: 9D04204

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Max. Marks: 60

Time: 3 hours

M.Tech II Semester Supplementary Examinations January/February 2017

CNC TECHNOLOGY & PROGRAMMING

(CAD/CAM)

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Answer any FIVE questions

All questions carry equal marks

1. (a) Explain various elements of machine control unit.
   (b) What are the important features of machining center used for higher production?
2. (a) What are the requirements of axes feed drives in CNC machine tools?
   

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   (b) Explain the arrangement of recirculation of balls in ball screw and state their advantages.
3. (a) What are the technical considerations that influence the automatic tool changer (ATC)?
   (b) List the different materials used in spindles and why AC spindles are selected in CNC machine tool.
4. (a) Explain the digital absolute encoder used for measurement of position and speed of rotary system.
   (b) Write short notes on Moire Fringes.

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5. Write a short note on:
   (a) Syncro-resolvers.
   (b) Laser interferometer.
6. The worktable of a positioning system is driven by a lead screw whose pitch = 6.0 mm. The lead
   screw is connected to the output shaft of a stepping motor through a gear box whose ratio is 5:1
   

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   (5 turns of the motor to one turn of the lead screw). The stepping motor has 48 step angles. The
   table must move a distance of 250 mm from its present position at a linear velocity = 500 mm/min.
   Determine: (i) How many pulses are required to move the table the specified distance.
   (ii) The required motor speed and pulse rate to achieve the desired table velocity.
7. Develop the part program for the following figure shown below, using APT language.
   

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   Ail dimensions in mm

8. (a) Discuss any four factors influencing selection of CNC machines.
   (b) What do you understand about the maintenance features of CNC systems and state the objectives
   of preventive maintenance?

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