Drill Tool Dynamometer (1)

7/25/2019 Drill Tool Dynamometer (1)

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INTRODUCTION

In the era of high competition, every manufacturing industry want to increase their

productivity, quality for satisfying their customer at the minimum production cost.Failure cost has the major role in the production cost. Hence the ideas of DRILL !!L

D"#$%!%&&R come in to picture 'y us. (ecause the main fault in the

manufacturing industry, in production line the failure of drill 'it.)henever the wor* is perform on the +#+ the cause of failure of drill 'it is the

difference in the composition of material in the another lot and when the operator wor*s

at manual drilling machine the cause of failure may 'e over pressure or load applied 'y

the operatorwor*er.

Hence the implementation of our project can reduce or eliminate this failure, 'ecause

with the help of drill tool dynamometer wor*er can see the load applied on the wor*

piece and he can stop the machine or can change the wor* -material if the load e/ceed

to the strength of drill 'it,so that the failure of drill 'it can 'e avoided.


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$ strain gauge type drilling dynamometer and its major components.


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TYPES OF DRILL MACHINES

SR.NO. DRILL MACHINE APPLICATION

1 0pright 1ensitive Drill 2ress

2 Radial $rm Drill 2ress

3 3ang Drill %achine

4 %ultiple 1pindle Drilling %achine

5 %icro Drilling %achine

6 urret ype Drilling %achine


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BASIC TYPES OF DRILLING MACHINES

Drilling machines or drill presses are one of the most common machines found in the

machine shop. $ drill press is a machine that turns and advances a rotary tool into a

wor* piece. he drill press is used primarily for drilling holes, 'ut when used with the

proper tooling, it can 'e used for a num'er of machining operations. he most common

machining operations performed on a drill press are drilling, reaming, tapping, counter

'oring, countersin*ing, and spot facing.

here are many different types or configurations of drilling machines, 'ut most drilling

machines will fall into four 'road categories4 upright sensitive, upright, radial, and

special purpose.

Uprig! "#$"i!i%# &ri'' pr#""


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Fig(r# 1Uprig! "#$"i!i%# &ri'' pr#""

he upright sensitive drill press -Figure 5

is a light6duty type of drilling machine that

normally incorporates a 'elt drive spindle

head. his machine is generally used for

moderate6to6light duty wor*. he upright

sensitive drill press gets its name due to the

fact that the machine can only 'e hand fed.

Hand feeding the tool into the wor* piece

allows the operator to 7feel7 the cutting

action of the tool. he sensitive drill press

is manufactured in a floor style or a 'ench

style.

Uprig! &ri'' pr#"" he upright drill press -Figure

8 is a heavy duty type of drilling machine

normally incorporating a geared drive

spindle head. his type of drilling machineis used on large hole6producing operations

that typically involve larger or heavier

parts. he upright drill press allows the

operator to hand feed or power feed the tool

into the wor* piece. he power feed

mechanism automatically advances the tool

into the wor* piece. 1ome types of upright

drill presses are also manufactured with

automatic ta'le6raising mechanisms.Fig(r# 2Uprig! &ri'' pr#""


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R)&i)' )r* &ri'' pr#""he radial arm drill press -Figure 9 is the hole producing wor* horse of the machine

shop. he press is commonly refered to as a radial drill press. he radial arm drill press

allows the operator to position the spindle directly over the wor*piece rather than move

the wor*piece to the tool. he design of the radial drill press gives it a great deal of

versatility, especially on parts too large to position easily. Radial drills offer power feed

on the spindle, as well as an automatic mechanism to raise or lower the radial arm. he

wheel head, which is located on the radial arm, can also 'e traversed along the arm,

giving the machine added ease of use as well as versatility. Radial arm drill presses can

'e equipped with a trunion ta'le or tilting ta'le. his gives the operator the a'ility to

drill intersecting or angular holes in one setup.


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Fig(r# 3 R)&i)' )r* &ri'' pr#""

SPECIAL PURPOSE DRILL MACHINES

here are a num'er of types of special purpose drilling machines. he purposes of these

types of drilling machines vary. 1pecial purpose drilling machines include machines

capa'le of drilling 8: holes at once or drilling holes as small as :.:5 of an inch.

G)$g &ri'' pr#""


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Fig(r# 4G)$g &ri'' pr#""

he gang style drilling machine -Figure ; or

gang drill press has several wor* heads

positioned over a single ta'le. his type of

drill press is used when successive operations

are to 'e done. For instance, the first head

may 'e used to spot drill. he second head

may 'e used to tap drill. he third head may

'e used, along with a tapping head, to tap thehole. he fourth head may 'e used to

chamfer.

M('!i"pi$&'# &ri'' pr#""


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he multiple spindle drilling machine is commonly

refered to as a multispindle drill press. his special

purpose drill press has many spindles connected to one

main wor* head -Figure


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Fig(r# 6Mi+r, &ri'' pr#""

T(rr#! !-p# &ri''i$g *)+i$#urret drilling machines are

equipped with several drilling heads

mounted on a turret -Figure =. &ach

turret head can 'e equipped with a

different type of cutting tool. he turret

allows the needed tool to 'e quic*ly

inde/ed into position. %odern turret

type drilling machines are computer6

controlled so that the ta'le can 'e

quic*ly and accurately positioned.Fig(r# 6CNC !(rr#! !-p# &ri''i$g *)+i$#


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TYPES OF DRILL BITS

Sr.N,. N)*# , T,,' Bi!" Sp#+ii+)!i,$

1 ungsten +ar'ide Inserts

2 Roller +one 'its &ach cone has teeth made of hard steel,

tungsten6car'ide

3 1elf 1harpening (its

4 2oly +rystalline Diamonds -2D+

5 Fishing tools


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DRILL TOOL SPECIFICATIONS

I$+ M* S#g*#$!

5;> = 568.


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8>


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#e/t, we assume that we are also measuring two perpendicular cutting forces that are

horiEontal, and perpendicular to the figure a'ove. his then allows us to e/amine specific forces

involved with the cutting. he cutting forces in the figure 'elow -Fc and Ft are measured using

a tool force dynamometer mounted on the lathe.


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1.2.1 F,r+# C)'+(')!i,$"

5.8.5.5 6 Force +alculations


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he forces and angles involved in cutting are drawn 'elow,

Having seen the vector 'ased determination of the cutting forces, we can now loo* at

equivalent calculations


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he velocities are also important, and can 'e calculated for later use in power calculations.

he elocity diagram 'elow can also 'e drawn to find cutting velocities.


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$ final note of interest to readers not completely familiar with vectors,

the forces Fc and Ft, are used to find R, from that two other sets of equivalent forces are found.

1.2.1.2 / M#r+)$!0" F,r+# Cir+'# i! Dr)!i$g Op!i,$)'

%erchantGs Force +ircle is a method for calculating the various forces involved in the cutting

process. his will first 'e e/plained with vector diagrams, these in turn will 'e followed 'y a

few formulas.

he procedure to construct a merchants force circle diagram -using drafting

techniquesinstrumentsis,


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5. 1et up /6y a/is la'eled with forces, and the origin in the centre of the page.

he scale should 'e enough to include 'oth the measured forces.

he cutting force -Fc is drawn horiEontally, and the tangential force -Ft is drawnvertically.

-hese forces will all 'e in the lower left hand quadrant

-#ote4 square graph paper and equal / y scales are essential

8. Draw in the resultant -R of Fc and Ft.

9. Locate the centre of R, and draw a circle that encloses vector R. If done correctly, the heads

and tails of all 9 vectors will lie on this circle.;. Draw in the cutting tool in the upper right hand quadrant, ta*ing care to draw the correct ra*e angle - from

the vertical a/is.


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CONCEPT OF TOOL DYNAMOMETER

he cutting force measurements allow in the past to analyEe and develop

accurate conventional cutting methods. #owadays with a constant demand for high

precision machining oriented to high accuracy and even smaller dimensions also, the


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development of relia'le and sensitive measuring instruments assumes a wide

importance. In fact they have a fundamental role in the analysis, optimiEation and

monitoring of a machine processes, selecting machines, tools and materials. Forcemeasurements are also fundamental for the definition of optimum cutting conditions, the

'rea*age 'ehavior of the micro end mills, the process of chip formation and how they

influence the cutting forces and the machining process. +utting speed, depth of cut, feed

rate, wor* piece material, tool material, cutting geometry, wear of the tool and cutting

fluid are the main factors determining the magnitude and direction of cutting forces.

However the small diameter of the tools requires high rotational speeds to

ahieve a reasona!le utting speed and material removal rate" #ith suh

rotational speed$ in the order of ten thousand of rotation per minute$ the tool

e%itation on the wor& piee has high frequen'" (his requires measuring

sensors with a orrespondingl' high natural frequen' in order to avoid

resonane" )oreover the fore pea&s are ontained in the range of few

newtons"

1.1 GENERAL ASPECTS

he term dynamometer refers to an instrument used to measure force. It can also

'e used to refer to a testing machine capa'le of applying force of a given precision. $

dynamometer is composed of a transducer comprising a metallic test specimen which

receives the force to 'e measured and deforms elastically 'y the application of this

force. In modern transducers such deformation -strain is communicated to a miniature

electric circuit attached to the test specimen, resulting in a modification of the electric

resistance. his resistance variation is measured 'y the )heatstone 'ridge method,

where'y two legs of the electric circuit are supplied with an analog voltage, continuous

or intermittent and an analogue voltage varia'le according to the force applied to the

dynamometer is collected 'etween the two other legs in the circuit.

he necessary equipment to supply voltage, collect and process the output signal and

display usa'le values constitutes the electronic element connected to the transducer.

raditional electronic instruments sta'iliEed and multimeter supply can 'e used.


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ransducer manufacturers have developed specific electronic equipment allowing to

optimiEe settings, measurement conditions and precision.

he latest advances in the technique of dynamometers consist in integrating the

electronic equipment associated to the digitaliEation of the signal and the transducer, so

as to constitute a single device that powered 'y 88: , releases an output digital signal

according to the force applied to the transducer.

)hen the relationship 'etween the force applied to a dynamometer and the

measurement of its output signal cannot 'e accurately determined 'y means of a

calculation, it is necessary to cali'rate the dynamometer, which consists in esta'lishing

the e/act relationship 'etween the force applied to a dynamometer 6 input 6 and the

electrical signal it releases 6 output. In essence, the operation consists in applying forcesthat can 'e accurately measured to a dynamometer and registering the values provided

'y the electronic equipment connected to the transducer. his operation is generally

performed 'y applying the protocol esta'lished 'y the international standard I1! 9@=.

his standard provides for a classification of the dynamometer according to precision

criteria. he results of the cali'ration of a dynamometer lead to the determination of a

mathematical polynomial of 8nd or 9rd degree, which allows calculating the value of the

force applied to the dynamometer 'ased on the indication provided 'y the electronic

equipment. he formula allowing calculating the level of uncertainty of this value is also

part of the cali'ration. Dynamometers are often used as the sensitive element of

weighing instruments. In this case, the shape of the test specimen is determined so as to

o'tain an output signal that is e/actly proportional to the mass of the specimen placed on

the of the instrument loading tray.

1.2 DYNAMOMETER

$ dynamometer or 7dyno7 for short is a machine used to measure torque and

rotational speed-rpm from whichpowerproduced can 'e measured.

1.2.1 D#"ig$ Cri!#ri,$" )$& M)!#ri)' , D-$)*,*#!#r
http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Rotational_speedhttp://en.wikipedia.org/wiki/Revolutions_per_minutehttp://en.wikipedia.org/wiki/Power_(physics)http://en.wikipedia.org/wiki/Rotational_speedhttp://en.wikipedia.org/wiki/Revolutions_per_minutehttp://en.wikipedia.org/wiki/Power_(physics)http://en.wikipedia.org/wiki/Torque


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1ensitivity, rigidity, elasticity, accuracy, easy cali'ration, cost and relia'ility in

the cutting environment have 'een ta*en into account in designing the dynamometer.

Dimensions, shape and material of dynamometer are considered to 'e effective factorson dynamic properties of the dynamometer. $ dynamometer essentially consists of an

important ring element. he rigidity, high natural frequency, corrosion resistance and

high heat conductivity factors were ta*en into consideration while selecting the ring

materials. $lso, deformation under the load should conform to that of strain gauges.

1.3 TYPES OF DYNAMOMETER

SR.NO. DYANMOMETER SPECIFICATION

1 &ddy +urrent Dynamometer

2 %agnetic 2owder Dynamometer

3 Hysteresis (ra*e Dynamometer

4 &lectric %otor3enerator Dynamometer

5 1train 3auge ype Dynamometer

1"3"1 *dd' +urrent ,'namometer

&+ dynamometers are currently the most common a'sor'ers used in modern

chassis dyno. he &+ a'sor'ers provide the quic*est load change rate for rapid load

settling. 1ome are air cooled, 'ut many require e/ternal water cooling systems. &ddy

current dynamometers require the ferrous core or shaft, to rotate in the magnetic field to


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produce torque. Due to this, stalling a motor with an eddy current dyno is usually not

possi'le.

1"3"2 )agneti -owder ,'namometer

$ magnetic powder dynamometer is similar to an eddy current dynamometer, 'ut

a fine magnetic powder is placed in the air gap 'etween the rotor and the coil. he

resulting flu/ lines create 7chains7 of metal particulate which are constantly 'uilt and

'ro*en apart during rotation creating great torque. 2owder dynamometers are typically

limited to lower R2% due to heat dissipation issues.

1"3"3 H'steresis ,'namometer

Hysteresis dynamometers, such as %agtrol IncMs HD series, use a proprietary

steel rotor that is moved through flu/ lines generated 'etween magnetic pole pieces.

his design allows for full torque to 'e produced at Eero speed, as well as at full speed.

Heat dissipation is assisted 'y forced air. Hysteresis dynamometers are one of the most

efficient technologies in small dynamometers.

1"3"4 *letri )otor./enerator ,'namometer

&lectric motorgenerator dynamometers are a specialiEed type of adjusta'le6

speed drives.he a'sorptiondriver unit can 'e either an alternating current-$+ motor

or a direct current-D+ motor. &ither an $+ motor or a D+ motor can operate as a

generator which is driven 'y the unit under test or a motor which drives the unit under

test. )hen equipped with appropriate control units, electric motorgenerator

dynamometers can 'e configured as universal dynamometers. he control unit for an $+
http://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_generatorhttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_generatorhttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_current


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motor is a varia'le6frequency driveand the control unit for a D+ motor is a D+ drive. In

'oth cases, regenerative control units can transfer power from the unit under test to the

electric utility. )here permitted, the operator of the dynamometer can receive payment-or credit from the utility for the returned power.

1.3.5 D-$)*,*#!#r i! S!r)i$ G)(g#

he traditional configuration of a dynamometer for cutting force measurements

in drilling operations consists of four elastic octagonal rings on which strain gages are

mounted with the necessary connection to form the )heatstone measuring 'ridge.

1emiconductor strain gages are small in siEe and mass, low in cost, easily attached and

highly sensitive to strain 'ut insensitive to am'ient or process temperature variations.

1train gages required simple construction 'ut tend to change resistance with the time so

they are suita'le for test of short duration the rings are fi/ed and held 'etween two metal

plates.

his type of dynamometer produces an output voltage corresponding to the

elastic deformation of its structure under an applied force. !ne of the critical pro'lems is

the stiffness of the components that is in conflict with the sensitivity of the

dynamometer however the main limitation is the low 'andwidth of the system.

1.4 STRAIN GAUGE

It is a device used to determine the strain at a specified place. he smallest gauge

developed and sold commercially to date is the electric resistance type. his gauge is

prepared from an ultra thin alloy foil which is photo etched to produce the intricate grid

construction with a gauge of :.8mm. !n the other hand, mechanical strain gauges are

still employed in civil engineering structural application where the gauge length is8::mm -(erry strain gauge. hese (erry gauges are rugged, simple to use and

sufficiently accurate in structural application where the stain distri'ution is

appro/imately linear over the 8::mm gauge length.
http://en.wikipedia.org/wiki/Variable-frequency_drivehttp://en.wikipedia.org/wiki/Adjustable-speed_drive#DC_Driveshttp://en.wikipedia.org/wiki/Variable-frequency_drivehttp://en.wikipedia.org/wiki/Adjustable-speed_drive#DC_Drives


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1train gauge system has four 'asic characteristics namely gauge length,

sensitivity, range of strain and the accuracy or precision.

3auge length is the distance 'etween two *nife edges in contact with the

specimen and 'y the width of mova'le *nife edges in a mechanical strain gauge.

1ensitivity is the smallest value of strain which can 'e read on the scale

associated with the strain gauge.

Range represents the ma/imum strain which can 'e recorded without resetting

the strain gauge.

2recision is ery sensitive instruments are quite prone to errors unless they are

employed with at most precision.

1train 3auges are 'roadly classified as follows

%echanical

!ptical

&lectrical

$coustical

1.4.1 E'#+!ri+)' S!r)i$ G)(g#&lectrical 1train 3auges are classified as 'ellow

1.4.1.1 R#"i"!)$+# S!r)i$ G)(g#

he resistance of an electrically conductive material changes with dimensional

changes which ta*e place when the conductor is deformed elastically.

)hen such a material is stretched, the conductors 'ecome longer and narrower,

which causes an increase in resistance. his change in resistance is then converted to ana'solute voltage 'y a wheatstone 'ridge. he resulting value is linearly related to strain

'y a constant called the gauge factor. his is the type of strain gauge are 'eing used in

the la'oratory.


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1.4.1.2 C)p)+i!)$+# S!r)i$ G)(g#

+apacitance devices, which depend on geometric features, can 'e used to

measure strain. he capacitance of a simple parallel plate capacitor is proportional to4

N-5.5)here4

Cis the capacitance,

)is the plate area,

is the dielectric constant, and

!is the separation 'etween plates.

he capacitance can 'e varied 'y changing the plate area OaG or the gap OtG. he

electrical properties of the materials used to form the capacitor are relatively

unimportant. 1o capacitance strain gauge materials can 'e chosen to meet the

mechanical requirements. his allows the gauges to 'e more rugged, providing asignificant advantage over resistance strain gauges.


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1.4.1.3 P,!,#'#+!ri+ S!r)i$ G)(g#

$n e/tensometer -an apparatus with mechanical levers attached to the specimen

is used to amplify the movement of a specimen. $ 'eam of light is passed through a

varia'le slit, actuated 'y the e/tensometer, and directed to a photoelectric cell. $s the

gap opening changes, the amount of light reaching the cell varies, causing a varying

intensity in the current generated 'y the cell.

1.4.1.4 S#*i+,$&(+!,r S!r)i$ G)(g#In pieEoelectric materials, such as crystalline quartE, a change in the electronic

charge across the faces of the crystal occurs when the material is mechanically stressed.

he pieEoresistive effect is defined as the change in resistance of a material dueto an applied stress and this term is used commonly in connection with semiconducting

materials. he resistivity of a semiconductor is inversely proportional to the product of

the electronic charge, the num'er of charge carriers, and their average mo'ility. he

effect of applied stress is to change 'oth the num'er and average mo'ility of the charge

carriers. (y choosing the correct crystallographic orientation and doping type, 'oth

positive and negative gauge factors may 'e o'tained. 1ilicon is now almost universally

used for the manufacture of semiconductor strain gauges.

1.4.2 Op!i+)' S!r)i$ G)(g#

1.4.2.1 P,!,#')"!i+ S!r)i$ G)(g#

)hen a photo elastic material is su'jected to a load and illuminated with

polariEed light from the measurement instrumentation -called a reflection polariscope,

patterns of color appear which are directly proportional to the stresses and strains within

the material. he sequence of colors o'served as stress increases is4 'lac* -Eero stress,

yellow, red, 'lue6green, yellow, red, 'lue6green, yellow, red, etc. he transition linesseen 'etween the red and green 'ands are *nown as 7fringes.7 he stresses in the

material increase proportionally as the num'er of fringes increases. +losely spaced

fringes mean a steeper stress gradient, and uniform color represents a uniformly stressed

area. Hence, the overall stress distri'ution can easily 'e studied 'y o'serving the


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numerical order and spacing of the fringes. Furthermore, a quantitative analysis of the

direction and magnitude of the strain at any point on the coated surface can 'e

performed with the reflection polariscope and a digital strain indicator.

1.4.2.2 M,ir# I$!#r#r,*#!r- S!r)i$ G)(g#

%oire interferometry is an optical technique that uses coherent laser light to

produce a high contrast, two6'eam optical interference pattern. %oire interferometry

reveals planar displacement fields on a partMs surface, which is caused 'y e/ternal

loading or other source deformation. It responds only to geometric changes of the

specimen and is effective for diverse engineering materials. +ontour maps of planar

deformation fields can 'e generated from / and y components of displacements.

1.4.2.3 H,',gr)pi+ I$!#r#r,*#!r- S!r)i$ G)(g#

Holographic interferometry allows the evaluation of strain, rotation, 'ending,

and torsion of an o'ject in three dimensions. 1ince holography is sensitive to the surface

effects of an opaque 'ody, e/trapolation into the interior of the 'ody is possi'le in some

circumstances. In one or more dou'le6e/posure holograms, changes in the o'ject are

recorded. From the fringe patterns in the reconstructed image of the o'ject, theinterference phase6shift for different sensitivity vectors are measured. $ computer is

then used to calculate the strain and other deformations.

1.5 BASIC CHARACTERISTICS OF A STRAIN GAUGE


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he gauge should 'e of e/tremely small siEe -gauge length and width so as

to adequately estimate strain at a point. he gauge should 'e of significant mass to 'e permit the recording of

dynamic strain. he strain sensitivity and accuracy of the gauge should 'e significantly high.

he gauge should 'e unaffected 'y temperature, vi'ration, humidity and

other am'ient condition. he gauge should 'e capa'le of indicating 'oth static and dynamic strains.

It should 'e possi'le to read the gauge either on location or remotely.

he gauge should e/hi'it linear response to strain.

he gauge and associated equipment should 'e availa'le at reasona'le cost.

he gauge should 'e suita'le for use as a sensing element or other transducer

systems.

1.6 ADANTAGES 7 DISADANTAGES OF STRAIN GAUGE

he advantages of strain gauge are4

1mall siEe and mass

&ase of production over a range of siEes

Ro'ustness

3ood sta'ility, repeata'ility and linearity over large strain range

3ood sensitivity

Freedom from -or a'ility to compensate for temperature effects and other

environmental conditions

1uita'ility for static and dynamic measurements and remote recording


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Low cost

T# &i")&%)$!)g#" , "!r)i$ g)(g# )r#8

Relatively high temperature sensitivity

1emiconductor types are e/tremely nonlinear

he semiconductor gauge is considera'ly more e/pensive than ordinary

metallic gauge

D#"ig$ r#9(ir#*#$!" ,r T,,' : ,r+# D-$)*,*#!#r"

For consistently accurate and relia'le measurement, the following requirements are

considered during design and construction of any tool force dynamometers 4

S#$"i!i%i!- 4 the dynamometer should 'e reasona'ly sensitive for precision

measurement

Rigi&i!- 4 the dynamometer need to 'e quite rigid to withstand the forces without

causing much deflection which may affect the machining condition

Cr,"" "#$"i!i%i!- 4 the dynamometer should 'e free from cross sensitivity such that

one force -say 2P

does not affect measurement of the other forces -say 2Q

and

2"

1ta'ility against humidity and temperature

uic* time response


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High frequency response such that the readings are not affected 'y vi'ration within

a reasona'ly high range of frequency

+onsistency, i.e. the dynamometer should wor* desira'ly over a long period.

TOOL DYNAMOMETER

he dynamometers 'eing commonly used now6a6days for measuring machining forces

desira'ly accurately and precisely -'oth static and dynamic characteristics are

either strain gauge typeor pieEoelectric type

1train gauge type dynamometers are ine/pensive 'ut less accurate and consistent,

whereas, the pieEoelectric type are highly accurate, relia'le and consistent 'ut very

e/pensive for high material cost and stringent construction.

T(r$i$g D-$)*,*#!#r

urning dynamometers may 'e strain gauge or pieEoelectric type and may 'e of one,

two or three dimensions capa'le to monitor all of 2Q

, 2"

and 2P

.

For ease of manufacture and low cost, strain gauge type turning dynamometers are

widely used and prefera'ly of 8 S D -dimension for simpler construction, lower cost

and a'ility to provide almost all the desired force values.Design and construction of a strain S gauge type 8 S D turning dynamometer are shown

schematically in Fig. 5:.A and photographically in Fig. 5:.C wo full 'ridges comprising

four live strain gauges are provided for 2P

and 2Q

channels which are connected with

the strain measuring 'ridge for detection and measurement of strain in terms of voltage

which provides the magnitude of the cutting forces through cali'ration. Fig. 5:.5:


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pictorially shows use of 9 S D turning dynamometer having pieEoelectric transducers

inside.

2hotographs of a strain gauge type 8 S D turning dynamometer and its major components.

0se of 9 S D pieEoelectric type turning dynamometer.

Dri''i$g &-$)*,*#!#r


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2hysical construction of a strain gauge type 8 S D drilling dynamometer for measuring

torque and thrust force is typically shown schematically in Fig. 5:.55 and pictorially in

Fig. 5:.58. Four strain gauges are mounted on the upper and lower surfaces of the two

opposite ri's for 2Q

S channel and four on the side surfaces of the other two ri's for the

torque channel. (efore use, the dynamometer must 'e cali'rated to ena'le determination

of the actual values of and 2Q

from the voltage values or reading ta*en in 1%( or 2+.

1chematic view of construction of a strain gauge type drilling dynamometer.

Mi''i$g &-$)*,*#!#r

1ince the cutting or loading point is not fi/ed w.r.t. the jo' and the dynamometer, the jo'

platform rests on four symmetrically located supports in the form of four !6rings. he


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forces on each !6ring are monitored and summed up correspondingly for getting the

total magnitude of all the three forces in Q, " and P direction respectively.

Fig. 5:.59 shows schematically the principle of using !6ring for measuring two forces

'y mounting strain gauges, ; for radial force and ; for transverse force.

Fig. 5:.5; typically shows configuration of a strain gauge type 9 S D milling

dynamometer having ; octagonal rings. 2ieEoelectric type 9 S D dynamometers are also

availa'le and used for measuring the cutting forces in milling

$ typical strain gauge type 9 S D milling dynamometer.

Gri$&i$g &-$)*,*#!#r

he construction and application of a strain gauge type -e/tended !6ring grinding

surface dynamometer and another pieEoelectric type are typically shown in Fig. 5:.5

REFRENCE

5. (ec*with 3 and Lewis (uc* # -5CA8 %echanical measurements.


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75

;. Ting ( and Foschi R! -5C=C +ross ring dynamometer for direct force resolution into

three

!rthogonal components. Int. U. %achine oll Design Res. ;, 9;


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76


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Documents

Drill Tool Dynamometer (1)