This set of Engineering Metrology Multiple Choice Questions & Answers (MCQs) focuses on “Rotary Tables”.
1. Which of the following is used in mechanical type rotary tables?
a) Bevel gear
b) Spur gear
c) Worm and gear
d) Pinion gear
Explanation: Mechanical rotary table which is cam compensated employs worm and gear as the angle measuring element but cam-compensation of gear error established the final accuracy of this type of rotary table.
2. What is the principle on which precision index table works?
a) Circle divider
b) Taylor’s principle
c) Principle of least square
d) Interference principle
Explanation: Rotary tables are the best-known and widely used circle dividing instrument. Precision index table is a type of rotary table. It is a serrated tooth table which is based on the principle of circular divider.
3. How many teeths are present in the serrated divider in precision index table?
Explanation: The indexing in precision index table corresponds to the number of teeth through which the table is indexed. The serrated divider is limited to 360 teeth. Serrated teeth indexer has been developed in 0.25° increment with accuracy of ± 0.1 second of arc.
4. By which curve, the small increments of angles are achieved in averaging type optical rotary machines?
a) Tan curve
b) Cos curve
c) Sine curve
d) Cot curve
Explanation: Smaller increments of angle are achieved by the sine curve which is generated by electronic or optical pulsing in the averaging type optical rotary table. The circular scale could be read by electrical or by Moire fringe method.
5. How the final unresolved error can be overcome in a mechanical cam compensated rotary table?
a) By the perfection of gear
b) By compensation
c) There is no unresolved final error
d) Perfection of gear is the better in this case than compensation
Explanation: In mechanical cam-compensated type rotary table, accuracy depends upon the accuracy of the worm and gear. Compensation is used to overcome the final unresolved error, rather than perfection of the gear.
6. How many face gears are used by precision index table?
Explanation: Precision index table uses two face gears. Both the gears have serrated teeth. Both gears are same in diameter, shape and number of teeth. When both face gears are brought into contact root to crest, then lock together and prevent rotation.
7. Which of the following is not true for the periodic error in worm and gear rotary table?
a) It can be affected by tooth spacing of the gear
b) This error is not taken into consideration
c) It can be affected by the thread form
d) It is the error within two turn of the hand wheel
Explanation: The periodic error is the error within one turn of the hand wheel. It is not taken into consideration. This error is affected by factors like the thread form and tooth form, drunkenness, line up, runout of worm, errors of eccentricity, and spacing of tooth of the gear.
8. What is the effect of lack of true spindle rotation in accurate worm and gear rotary table?
a) Angular error
b) Centre distance error
c) Both angular and centre distance error
d) Decrease repeatability
Explanation: Lack of true spindle rotation in accurate worm and gear rotary table results in both angular error and centre distance error. Rotary table has the advantage of trouble free operation and good repeatability.
9. Which of the following option is true about rotary tables?
Statement 1: Index is not used with optical rotary table.
Statement 2: Accurate worm and gear rotary table can be used with an index plate.
a) T, T
b) T, F
c) F, T
d) F, F
Explanation: It can be used with an index plate to divide the circle, without the loss of accuracy and necessity of reading angle. Optical rotary table cannot use index, because it’s worm and gear is not accurate.
10. Which of the following is true for accurate worm and gear rotary tables?
a) Bidirectional approach is used for setting
b) Can be used for inspection of angles
c) Can’t be used for generation of angles
d) Worm and gear are highly accurate
Explanation: A unidirectional approach is used in accurate worm and gear type table for setting to take care of unavoidable presence of backlash. The accurate worm and gear has an advantage for the inspection and generation of angles.
Sanfoundry Global Education & Learning Series – Engineering Metrology.
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