function of mechanical comparator
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Mechanical Comparators
1. COMPARATORS
2. The general principle of comparator is to indicate the differences in size between the standard and the work being measured by means of some pointer on a scale with sufficient magnification It thus does not measure the actual dimension but indicates how much it differs from the basic dimension
3. All comparators consist of three basic features 1)A sensing device • which faithfully senses the input signal 2) A Magnifying or amplifying system • to increase the signal to suitable magnitude. Mechanical, Optical, Pneumatic,hydraulic and electronic methods are used for this purpose. 3) A display system (usually a scale and pointer) Which utilizes the amplified signal to provide a suitable readout.
4. Need for a comparator A comparator is used in mass production to inspect the components to close tolerances with high degree of precision and speed. Ex: Piston • Use of line standards such as vernier and micrometer calipers require considerable skill • Many dimensions can be checked in a very short time Comparators can be classified as 1. Mechanical 2. Optical 3. Electrical &Electronic 4. Pneumatic 5. Fluid displacement comparators 6. Mechanical optical comparator 7. Electro-mechanical comparator 8. Multi-check comparator.
5. Design Consideration 1.Ability to record variation of at least 0.0025 mm 2.Linear recording scale 3.Variance free (Instrument readings should not vary when repeated measurements of given quantity are made 4.Scale indicators clear and free from oscillations 5.Free from backlash, unnecessary friction &clearances inertia should be low. 6.Measuring pressure should be low and constant 7.Supporting frame to be rigid and withstand reasonable ill usage without permanent damage 8.Capable of measuring wide range.