3. Linear & Angular Measuring Instruments(not started).pptx

8/12/2019 3. Linear & Angular Measuring Instruments(not started).pptx

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A . B . M . M A I N U L B A R IL E C T U R E R , D E P T. O F I P E

IPE 381Linear & Angular Measuring

Instrument


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Outline

LinearMeasurements

Calipers

V-BlockEngineer's taper, wire & thicknessgaugePitch Screw Gauge

VernierInstrumentsMicrometer

Telescopic InternalGaugeHemispherical

GaugeSlip GaugePivotal Stylus & Autocollimator Accessories

Surface Plate Angle Plate

AngularMeasurements

Pin Gauge

Bevel ProtractorSine BarSprit Level Autocollimator

MiscellaneousMeasurements

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Linear Measurement

CalipersConsists of two legs Accessory to scaleReduce sighting errors and increase accuracy

Two types:Firm Joint typeOutsideInside

Spring type

OutsideInsideTransferHermophrodite

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Linear Measurement

V-BlockChecking roundness of cylindrical workpieceMarking centers accurately90 angleTypes

Depending on accuracyGrade AGrade B

Depending on designOne veeTwo vee

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Linear Measurement

Engineer's taper, wire &thickness gauge

Consists of leaves forTaper measurement Wire diameter measurementThickness of small gaps

Pitch Screw GaugeContains multiple leavesMatches teeth on the leaves with teeth on work

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Linear Measurement

Vernier InstrumentsTwo scales: Main & VernierSlight difference in divisions is used enhance the accuracyThree elements: Beam, Fixed Jaw & Sliding JawErrors in measurementsDigital Caliper

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Linear Measurement

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Vernier Height GaugeSort of Vernier CaliperHave attachment tomake suitable for heightmeasurement


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Linear Measurement

MicrometersU shapedInsideMicrometer depth gauge

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Linear Measurement

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Telescopic Internal Gauge

It is used for the measurement of internal diameter of a hole during machiningoperation (Fig). It consists of two spherical contacts carried on two rods. The tworods can slide within a tube and are forced apart by an internal spring. For taking themeasurements the spring unit is compressed and inserted into the hole. The contactsthen move out so as to press on the surface. They are then locked in position bymeans of a locking screw. The telescopic gauge is then taken out and the dimensionacross two tips is measured by some other external measuring instrument.Telescopic gauge can be used for big bores only.


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TelescopicInternal Gauge


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Linear Measurement

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Hemispherical Gauge

For the measurement of bores that are too small, hemispherical gauge isconsidered to be very useful. It consists of the spring steel arms havinghemispherical ends, within which is a wedge shaped member attached to aspindle which can be moved endwise by a knurled head (Fig).Thus thehemispheres can be expanded or contracted by the movement of the wedge. Again this gauge is also operated by the sense of feel.


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Linear Measurement

Pin GaugeFor larger boresHas spherical endsLength is slightly less than the diameter to be measured

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Linear Measurement

Pivotal Stylus & Autocollimator

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Linear Measurement

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Linear Measurement

Slip GaugeRectangular blocks of 30 by 10 mmSurface hardened Wrung together due tofine finish (6-7 x 10 -6mm)

AccessoriesSurface Plate Angle Plate

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Angular Measurement

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Angle Gauge


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Angular Measurement

Bevel ProtractorBase plate contains a main scale with which there is anattached vernier scale. Adjustable blade moves along thecircular periphery of the main scale.

Various components:BodyStockBlade

Use of bevel protractor

Checking inside bevel faceChecking vee blockMeasuring acute angle

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Angular Measurement

Sine BarUses the ratio of the length of two sides of a right triangle inderiving a given angle.Measurement is usually limited to 45 0 Not complete: needs surface plate, slip gauges & indicatingdevice.Made from high carbon, high chromium, corrosion resistantsteel

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Angular Measurement

Accuracy of sine bar depends on following features:Two rollers must have equal diameter and be true cylindersThe rollers must be set parallel to each other and to the upperfaceThe precise center distance between the rollers must be knownThe upper surface must have a high degree of flatness

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Angular Measurement

Sprit LevelPurpose: Measuring small angle and positioning surfaceparallel to horizontal or vertical planeConsists of sealed glass tube on which scale is engraved. Tubeis filled with ether leaving the top part for ether vapor whichforms a bubble

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Sprit Level

Angular Measurement


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Angular Measurement

Characteristic element of a levelSensitivity: expressed as the angle of tilt in seconds for which bubble will move by one division on the tube

Sensitivity = Angle in seconds/1 division of tube

Constant of sprit level: change in tilt, expressed in mm/m Accuracy of level: base should be flat within prescribed limitsErrors: due to error in the vial, curvature being non-uniform,scale positioned incorrectly and temperature variations

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Angular Measurement

AutocollimatorInfinity telescope and collimator combined into one An optical instrument used for small angular differencesProvides very sensitive and accurate approach

ApplicationMeasurement of straightness and flatnessPrecise angular indexing

Assessment of squarenessParrallelism of components

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Angular Measurement

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Angular Measurement

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THAT IS ALL FORTODAY

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3. Linear & Angular Measuring Instruments(not started).pptx