LINEAR MEASUREMENT. Prof.H M Prajapati & Prof. A R Sankhla

Transcription

1 LINEAR MEASUREMENT

2 Introduction Classification Based on the type of standard Line measurement End measurement Based on precision Precise Direct: Vernier caliper, Micrometer Indirect: Telescopic gauge, bore gauge Non-precise Direct: Steel rule Indirect: Caliper

3 Engineer s Steel rule Material: Hardened steel L. C. = 0.5 or 1 mm Length = 150, 300, 600, 1000 mm Types: Shrink rule, folded form Parallax

4 CALIPERS Material Leg: Carbon steel or alloy steel Hardness: 650 ±50 HV Spring: Carbon spring steel Classification Spring and Firm joint caliper Outside, Inside, Transfer, Hermophrodite Nominal size Firm joint caliper: 100, 150, 200, 300 mm Spring caliper: 75, 100, 150, 200, 250, 300 mm

5 Outside CALIPERS How to get numeric value?

6 Inside CALIPERS How to get numeric value?

7 CALIPERS Inside caliper (Firm joint & Spring) Outside caliper (Firm joint & Spring)

8 Transfer CALIPERS

9 Hermophrodite CALIPER

10 Divider

11 Vernier caliper When two scales or divisions slightly different in size are used, then difference between them can be utilized to enhance the accuracy of measurement.

12 Vernier Caliper Parts of vernier caliper

13 Vernier Caliper (cont.) All values are in cm Different L.C in vernier caliper

14 Vernier Caliper (cont.) Reading vernier caliper

15 Vernier Caliper (cont.) Type A vernier caliper

16 Vernier Caliper (cont.) Type B vernier caliper

17 Vernier Caliper (cont.) Type C vernier caliper

18 Vernier Caliper (cont.) Material Steel Hardness: 650 HV min. Range: 0-125, 0-200, 0-250, 0-300, 0-500, 0-750, , , 750, 2000 mm Flatness 0.05 mm for nominal lengths upto 300 mm Straightness 0.01 mm for measuring range of 200 mm Precautions in use Errors

19 Vernier Height Gauge

20 Vernier Height Gauge Base Flatness: mm Beam Parallelism of measuring jaw by mm/ 10 mm projection of scriber when 1 kg is applied at maximum height of scriber Straightness of guiding edge 0.02 (250), 0.04(500), 0.06(750), 0.08(1000) Flatness of beam face 0.04 (250), 0.06(500), 0.10(750), 0.12(1000) Perpendicularity 0.04 mm /100 mm

21 Vernier Height Gauge Measuring jaw and scriber Parallelism of jaw face with base: mm Graduation Thickness of graduation: 0.05 to 0.1 mm Length of graduation: 2 to 3 times the width of interval between adjacent lines Measure of height Slider Good sliding fit

22 Vernier Depth Gauge

23 Dial Caliper (cont.)

24 Digital Caliper

25 Micrometer Principal of Micrometer Micrometers work on the principle of screw and nut When a screw is turned through nut by one revolution, it advances by one pitch distance If circumference of the screw is divided into number of equal parts say n, its rotation through one division will cause the screw to advance through (pitch/n) length Thus the minimum length that can be measured by such arrangement will be ( pitch/n)

26 Least count of Micrometer L.C = (Pitch of the thread / total numbers of divisions on the thimble) = ( Pitch / n) = ( 0.5 / 50) L.C = 0.01

27 Micrometer

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29 Micrometer Frame Material Cast steel, steel or malleable cast iron, light alloy Stiffness: 1 kg force should not change distance by 1.5µm for 0-25 range, 2µm for range Anvil and spindle About 3mm protrusion from frame Tungsten carbide tip Ratchet driver 0.5 to 1 kgf Thimble and barrel Adjusting nut

30 How to read Micrometer? Zero error Reading a micrometer

31 VERNIER MICROMETER Vernier micrometer

32 Use of Ratchet Mechanism To maintain uniform contact pressure less than 1 kgf. It completely remove the error because of lack of sense of feel.

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34 Precaution used for micrometer The micrometer should be wiped clean and free from oil, dirt, dust etc. Start with zero setting on micrometer. Use spanner to correct the error with slight rotation of barrel. Micrometer dimension is set slightly larger than the size of Part whose dimensions to be measured and part is slid over the contact surfaces of micrometer. After this thimble is turned till the measuring tip just touches the part and the final movement should be done by ratchet. The micrometers are available is various sizes and ranges, select appropriate micrometer.

35 Errors Anvil and spindle tips should be parallel and flat to each other. Axis of both should be coincide to each other. Zero error. Wear of threads.

36 Depth micrometer

37 Inside micrometer spacing Collar Extension rods

38 Inside Micrometer Main Parts Measuring Head

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40 Possible ranges with extension bar

41 SLIP GAUGE Johannsen gauges Cross-section:30 mm 09 mm Classification As per accuracy Master slip gauge AA: ±2µ/m Reference slip gauge A: ±4µ/m Working slip gauge B: ±8µ/m As per grade Grade 2: Workshop grade Grade 1: Tool room work (setting up sine bar & Dual Gauge, checking gap gauges) Grade 0: Inspection grade (Inspection Dept.) Grade 00: Calibration of Grade 2

42 SLIP GAUGE

43 SLIP GAUGE Size Upt0 10 mm: 30 mm 9 mm Above 10 mm:35 mm 9 mm Grades Grade 0, Grade I, Grade II Material High grade steel with coefficient of thermal expansion (11.5±1.5) 10-6 per degree Celsius between 10 C and 30 C Hardness: 800HV Indian standard on slip gauges

44 SLIP GAUGE microns Wringing of slip gauges

45 Slip Gauge set as per Indian Standard M45/1 & M86/1

46 Selection of slip gauges for required Make a stake of dimension Always start with the last decimal place and deduct this from the required dimension. For example, let s the dimension is to be built up is Here for last decimal place of 0.009, select mm slip gauge. Now dimension left = = mm Select next smallest figure in the same way, find the remainder and continue this until the required dimension is completed

47 In our example second decimal place is 1.08,select 1.08 mm slip gauge Now remainder = = 53.2mm Now select 1.2 mm and 52 mm is the remaining dimension. Now select 2 mm slip gauge so remainder 50 mm. 50 mm slip gauge is available directly. Thus we have = mm

48 Care & Use of slip Gauges. Surfaces should be covered with petroleum jelly or other corrosive resistance coatings. When the gauges are not in use they should be kept in their case with size. The gauges should be used in air conditioner rooms free from dust and dirt. The fingering/handling of lapped faces should be avoided as far as possible that may corrode surfaces due to natural acid in the skin. The working surfaces should never be placed on surface plate. Use standard wringing process to make stake of gauges. The gauges should never be left wrung together for an unnecessary length of time. This may lead to micro cold welding which may cause pitting of surface when they are separated.

49 SURFACE PLATE Purpose Datum simulator for linear and angular measurement Test degree of flatness of other surfaces Material Properties Rigidity Wear resistance Hardness Corrosion resistance Capable to take high surface finish Material Cast Iron Granite Glass Manufacturing of plate Straightness 0.08 mm per meter Flatness ± to ±0.005 (150 mm diagonal) ± 0.02 to ±0.04 (2000 mm diagonal)

50 Care & Use of Surface Plate Before and after use of surface plate, it should be wiped clean from dust and other particles. Surface plate should be placed in stirred atmosphere under constant temperature control. Keep it away from direct sunlight. Load should be distributed over working surface. Full area of plate should be utilized. Do not concentrate on particular area. The excess metal due to burrs on the surface of CI surface plate should be removed. Flatness should be checked occasionally. Protect it against damage by direct falling of heavy objects. When not in use, it should always be kept oil lubricated in cover.

51 ANGLE PLATE Material Cast Iron Purpose Accessory to surface plate

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53 V-BLOCK Purpose To hold the object Checking roundness Marking centers Material Cast Iron Angle 90, 120

54 FEELER GAUGE Purpose To measure the gap/clearance between two flat parallel surfaces. Thickness 0.03 to 1 mm Width 10 mm at heel side 6 mm at tip Set Eight blades 0.03 to 0.1 in steps of 0.01

55 Sr No No. of blades Thickness of blades in mm to 0.1 in steps of , 0.03, 0.04, 0.04, 0.05, 0.05, 0.06, 0.07, , 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, , 0.04, 0.05, 0.06, 0.07, 0.1, 0.15, 0.2, 0.4, , 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.75, , 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.4, 0.75, , 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0

56 RADIUS GAUGE

57 THREAD PITCH GAUGE

58 STRAIGHT EDGE Purpose Checking straightness and flatness Material Steel (2 m) Cast Iron (3 m) Grade Grade A Scraping mm/100 mm Grade B Milling mm/100 mm Working length and total length

59 STRAIGHT EDGE (CONTD.)

60 Combination Set

61 COMBINATION SET

62 COMBINATION SET

63 SMALL BORE GAUGE

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65 TELESCOPIC GAUGE

66 PIN GAUGE METHOD TO MEASURE BORE DIAMETER

67 PIN GAUGE METHOD TO MEASURE BORE DIAMETER

68 Four Ball Method

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70 Parallax error numerical Chapter 1 Introduction Worked Examples Q 1.8 Book: Engineering Metrology by R K Jain

71 Transfer from line standard to end standard Chapter 3: Topic Book: Engineering Metrology by R K Jain Solved Examples: Q. 3.3 and 3.4