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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/Torque7/25/2019 Drill Tool Dynamometer (1)
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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 $+
http://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_generatorhttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_generatorhttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_current7/25/2019 Drill Tool Dynamometer (1)
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motor is a varia'le6frequency driveand the control unit for a D+ motor is a D+ drive. In
'oth cases, regenerative control units can transfer power from the unit under test to the
electric utility. )here permitted, the operator of the dynamometer can receive payment-or credit from the utility for the returned power.
1.3.5 D-$)*,*#!#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_Drives7/25/2019 Drill Tool Dynamometer (1)
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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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;. 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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