Bme Lab Manual Fe

VIDYA PRATISHTHAN’SCOLLEGE OF ENGINEERING, BARAMATI

DEPARTMENT OF MECHANICAL ENGINEERING

LABORATORY MANUAL

SUBJECT: BASIC MECHANICAL ENGINEERING[SUBJECT CODE: 102013]

CLASS: F.E.YEAR: 2011-12

APPROVED BY:

H.o.D. [Mech] PRINCIPALProf. P. R. Chitragar Dr. S. B. Deosarkar

VALIDITY UP TO: ACADEMIC YEAR 2012 – 2013

LABORATORY IN-CHARGE: PROF. SACHIN. M. BHOSLE

VIDYA PRATISHTHAN’SCOLLEGE OF ENGINEERING, BARAMATI

DEPARTMENT OF MECHANICAL ENGINEERING

List of ExperimentsYEAR: 20010-11 SUBJECT: Basic Mechanical Engineering

1. Assembly and working of 4-bar, 6- bar, 8-bar planar mechanisms.2. Finding relation between input angle and output angle for various link lengths.3. Demonstration of operations of centre Lathe4. Demonstration of operations on drilling machine5. Demonstration of Two stroke and four stroke engine6. Study of Package type boilers7. Study of domestic refrigerator & window air conditioner.8. Study of power transmitting elements: couplings, gears & bearings.9. Study Joule’s Porous plug experiment10. Joule’s paddle wheel experiment11. Experimental verification of effect of insulating material on heat transfer.

Prof. Sachin M. Bhosle[Lab-Incharge]

BASIC MECHANICAL ENGINEERING – LABORATORY MANUAL

DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE

EXPERIMENT NO. 1

TITLE: ASSEMBLY AND WORKING OF 4-BAR, 6-BAR, 8-BAR PLANARMECHANISMS

Aim: - To study of Assembly and working of 4-bar, 6-bar and 8-bar planarmechanism.Theory: - Kinematic links: A resistant body or group of resistant bodies withrigid connections preventing their relative movement is known as link. A link maybe defined as a member or a combination of members of a mechanism,connecting other members and having motion relative to them. Thus a link mayconsist of one or more resistant bodies. A slider crank mechanism consist offour links; Frame and guides, crank connecting rod and slider. However, theframe may consist of bearings for the crank shaft. The crank link may havecrankshaft and flywheel also, forming one link having no relative motion ofthese.

Links can be classified into Binary, ternary, quaternary etc. depending uponits ends on which revolute or turning can be placed.

Fig. 1Kinematic pair:

A kinematic pair or simply a pair is a joint of two links having relativemotion between them. In slider-crank mechanism, link 2 rotates relative to link



1 and constitutes a revolute or turning pair. Link 4 (slider) reciprocates relativeto link 1 and is a sliding pair.Type of kinematic pair:

Kinematic pairs can be classified according to Nature of contact Nature of relative motion

Kinematic pair according to nature of contacta) Lower pair: A pair of links having surface or area contact between

the members is known as a lower pair. The contact surfaces of the twolinks are similar.

Example: Nut turning on a screw, shaft rotating in a bearing, all pairs of aslider-crank mechanism, universal joint etc.

b) Higher pair: When a pair has appoint or line contact between thelinks, it is known as higher pair. The contact surfaces of the two links aredissimilar.

Example: wheel rolling on a surface, cam and follower pair, tooth gears,balls and roller bearings, etc.Kinematic pairs according Nature of relative motion

a) Sliding pair: If two links have a sliding motion relative to eachother, they form a sliding pair.

A rectangular rod in a prism is a sliding pair.b) Turning pair: when one link has a turning or revolving motion relative

to each other, they constitute a turning pair or revolving pair.In slider-crank mechanism, all pairs except the slider and guide pair are turningpairs. A circular shaft revolving inside a bearing is a turning pair.

c) Rolling pair: when the links of a pair have a rolling motion relative toeach other, they form a rolling pair, e.g. a rolling wheel on a flat surface,ball and roller bearing, the ball and the shaft constitute one rolling pairwhereas the ball and the bearing is the second rolling pair.

d) Screw pair: If two mating links have turning as well as slidingmotion between them, they form a screw pair. This is achieved by cuttingmatching threads on the two links.

The lead screw and the nut of a lathe is a screw pair.e) Spherical pair: when one link in the form of a sphere turns inside a

fixed link, it is spherical pair.The ball and socket joint is a spherical pair.Kinematic Chain:



A kinematic chain is an assembly of links in which the relative motions of thelinks is possible and the motion of each relative to the others is definite.

In case, the motion of a link results in indefinite motions of other links, it isa non-kinematic chain.Mechanism:

If one of the links of a kinematic chain is fixed to the ground and if motions ofeach link results in definite motions of the others, the linkage is known asmechanism.To obtain constrained or definite motions of some of the links of themechanism, it is necessary to know how many inputs are needed. In some linksand are said to have one degree of freedom. In other mechanism, two inputsmay be necessary to get a constrained motions of the another links and are saidto have two degrees of freedom and so on.Four bar mechanism:

A four bar mechanism is the most fundamental of the lane kinematiclinkages. It is much preferred mechanical device for the mechanization andcontrol of motion due to its simplicity and versatility. Basically it consists offour rigid links which are connected in the form of a quadrilateral by four pinjoints.

A link that make complete revolutions is the crank, the link opposite to thefixed link is the coupler and the fourth link a lever or rocker if oscillates or ananother crank, if rotates.A four bar mechanism has the following characteristics based on the lengths ofits link.1. It is impossible to have a four bar mechanism if length of the one of the

links is greater than the sum of the other three.2. If the sum of the lengths of the largest and the shortest links is less than

the sum of the other two links, the linkage is known as class-I, four- barmechanism.

Fig.2



If the links of the four bar mechanism obtained above, are fixed, differentmechanisms are obtained known as Inversion

a. Shortest link is fixedIf the shortest link is fixed, the adjacent link b and d makes completerevolutions. The mechanism thus obtained is known as crank- crank or doublecrank or rotary- rotary mechanism.

b. Link adjacent to the shortest link is fixed;If any of the link adjacent to the shortest link is fixed, the shortest link makescomplete revolution and acts as a crank, and the link opposite to the crank isoscillates. The mechanism is known as a crank-rocker or crank-lever mechanismor a rotary-oscillating converter.

c. link opposite to shortest link is fixed:If the shortest link a is made coupler and the link opposite to it, i.e. c, is fixed,the other two links b and d would oscillate. The mechanism is known as a rocker-rocker or double rocker or double lever mechanism or oscillating-oscillatingmechanism.

3. When the sum of the lengths of the shortest and largest links is morethan the sum of the lengths of the other two links known as class-II, four barmechanism. In such mechanism, fixing any of the links always results in arocker- rocker mechanism. In other words, the mechanism and its inversionsgive the same type of motion i.e. double-rocker mechanism.

4. Parallel-crank four-bar linkage: If in a four-bar linkage, two opposite linksare parallel and equal in length, then any of the links can be made fixed. Thefour links form a parallelogram in all the positions of the cranks, provided thecrank rotates in the same sense.The use of such a mechanism is made in the coupled wheels of locomotive inwhich the rotary motion of one wheel is transmitted to the other wheel. Forkinematic analysis, link d is treated as fixed and the relative motions of theother links are found. However, in fact, d has a translator motion parallel to thetrails.6-bar planar mechanism:

In case of four-bar chain does not provide the required performance of anapplication, one of the two single-degree of freedom six bar chain with seventurning or revolute pairs is considered. There are two types of six-bar chains.

1. Watt chain: In watt chain the ternary links are adjacent for Watt six-bar chain



Fig. 3 Watt-I & Watt-II mechanisms2. Stephenson chain: In Stephenson chain ternary links separated by binary

links refer fig. for Stephenson-I six-bar mechanism, For Stephenson-II six-barmechanism and For Stephenson-III six-bar mechanism. It may be noted that inboth these types of mechanism some triangular shaped links are truly ternarylinks while other are known as triangular to indicate the possible path of tracerpoints on floating links.

Fig. Stephenson -I, II &I II mechanisms

Conclusion: -

References:



EXPERIMENT NO. 2

TITLE: POWER TRANSMITTING ELEMENTS

Aim: - Study of Power transmitting element.Theory :- (**refer Dr. Kodgire’s Material Science and Metallurgy)Type of Fracture :- (**refer Dr. Kodgire’s Material Science and Metallurgy)

Shaft coupling:Shaft couplings are used to join two or more pieces of the shaft.

Types of shaft coupling:Shaft couplings are divided into two groups as follows

1) Rigid couplingIt is used to connect two shafts which are perfectly aligned. Following are

the type of rigid couplinga) Sleeve or muff couplingb) Clamp or split muff or compression coupling andc) Flange coupling

2) Flexible couplingIt is used to connect two shafts which are having both lateral and

angular misalignment. Following are the type of rigid couplinga) Bushed pin type couplingb) Universal couplingc) Oldham coupling

Sleeve or muff coupling:It is the simplest type of rigid coupling made of cast iron. It consists of a

hollow cylinder whose inner diameter is same as that of shaft. It is fitted overthe ends of the two shafts by means of a gib head key as shown in fig. thepower is transmitted from one shaft to the other shaft by means of sleeve.

Fig. 1Clamp or split muff or compression coupling:



In this case, the muff of sleeve is made into two halves and is boltedtogether as shown in fig. The shaft ends are made to abut each other and asingle key is fitted directly in the keyways of both the shafts. One-half of themuffs are fixed from below and the other half is placed from above. Both thehalves are held together by means of mild steel studs or bolts and nuts. Thenumber of bolts may be two, four or six. The nuts are recessed into the bodiesof the muff castings. This coupling may be used for heavy and moderate speeds.The advantage of this coupling is that the position of the shafts need not bechanged for assembling and disassembling of the coupling.

Flange coupling:A flange coupling usually applies to a coupling having two separates

cast iron flanges. Each flange is mounted on the shaft end and keyed to it. Thefaces are turned up at right angle to the shaft. One of the flanges has aprojected portion and the other flange has a corresponding recess. This helpsto bring the shafts into line and to maintain alignment. The two flanges arecoupled together by means of bolts and nuts. The flange coupling is adapted toheavy loads and hence it is used on large shafting.

Fig. 2Flexible coupling:A flexible coupling is used so as to permit an axial misalignment of the shaftwithout undue absorption of the power which the shafts are transmitting.Following are the type of different types of flexible couplings

1. Bushed pin flexible coupling:A Bushed pin flexible coupling is a modification of the rigid type of flangecoupling. The coupling bolts are known as pins. The rubber or leather bushes areused over the pins. The two halves of the coupling are dissimilar n construction.



A clearance of 5mm is left between the faces of the two halves of the coupling.There is no rigid connection between them and the drive takes place throughthe medium of the compressible rubber or leather bushes.

Fig. 3a. Oldham coupling

It is used to join two shafts which have lateral mis-alignment. it consist of twoflanges With slots and a central floating part with two tongues at right anglesas shown in fig. the central floating part is held by means of a pin passingthrough the flanges and the floating part. The tongue fits into the slot offlange and allows for ‘to and fro’ relative motion of the shafts, while anothertongue fits into the slot of another flange and allows for vertical relativemotion of the parts. The resultant of these two components of motion willaccommodate lateral misalignment of the shafts as they rotate.

Fig. 4



3. Universal or hook’s couplingA universal or hook’s coupling is used to connect two shafts whose axesintersect at a small angle. The inclination of the shafts may be constant, but inactual practice, it varies when the motion is transmitted from one shaft toanother. The main application of the universal coupling is found in transmissionfrom gear box to the differential or back axle of the automobiles. In such acase, we use two Hook’s coupling, one at each end of the propeller shaft,connecting the gear box at one end and the differential on the other end. Ahook’s coupling is also used for transmission of power to different spindles ofmultiple drilling machines.

Fig. 5

GearsGears are used to transmit motion from one shaft to another or between ashaft and a slide. This is accomplishing by successively engaging teeth.

Gears use no intermediate link or connector and transmit the motion bydirect. In this method, the surfaces of two bodies make a tangential contact.The two bodies have either a rolling or a sliding motion along the tangent at thepoint of contact.

Classification of gearsGears can be classified according to the relative positions of their shaft axesas follows:

1. Parallel shaftsRegard less of the manner of contact, uniform rotary motion between twoparallel shafts is equivalent to the rolling of two cylinders, assuming no slipping.Depending upon the teeth of the equivalent cylinder that is straight or helical,following are the main types of gears to join parallel shafts.



Spur GearsThey are straight teeth parallel to the axis and thus, are not subjected to axialthrust due to tooth load. At 6he time of engagement of two gears, the contactextends across the entire width on a line parallel to the axis of rotation. Thisresults in sudden application of the load, high impact stresses and excessivenoise at high speeds. Further, if the gears have external teeth on the outersurface of the cylinder, the shafts rotate in the opposite direction. In aninternal spur gear, the teeth are formed on the inner surface of an annulus ring.An internal gear can mesh with an external pinion (smaller gear) only and thetwo shafts rotate in the same direction as shown in the fig

.Fig. 5

Spur Rack And pinionSpur Rack is a special case of spur gear where it is made of infinite diameter sothat the pitch surface is plane. The spur rack and pinion combination convertsrotary motion into translatory motion, or vice versa. It is used in a lathe inwhich the rack transmits motion to the saddle.

Helical or helical spur gearsIn helical gears the teeth are curved, each being in helical in shape. Two matinggears have the same helix angle, but have teeth of opposite hands. At thebeginning of engagement contact occurs only at the point of leading edge of thecurved teeth, as the gears rotate, the contact extends along a diagonal lineacross the teeth. Thus, load application is gradual which results in low impact



stresses and reduction in noise. Therefore, the helical gears can be used athigher velocities than the spur gear and have greater load carrying capacity.

Helical gears have the disadvantage of having in thrust as there is a forcecomponent along the gear axis. The bearings and the assemblies mounting thehelical gears must be able to withstand thrust loads.

Fig. 62. Intersecting shafts

Kinematically, the motion between two intersecting shafts is equivalent to therolling of two cones, assuming no slipping.When teeth formed on the cones are straight, the gears are known as straight

bevel and when inclined, they are known as spiral or helical gear.

Straight bevel gearThe teeth are straight, radial to the point of intersection of the shaft axis andvary in cross section through out their length. Usually, they are used to connectshafts at right angles to each other are known as mitre gears, at the beginningof engagement , straight bevel gear make the line contact similar to spur gear.They can also be internal bevel gears analogous to internal spur gears.



Fig. 7

Spiral bevel gear:When the teeth of a bevel gear are inclined at an angle to the face of thebevel, they are known as spiral bevel or helical bevels. They are smoother inaction and quieter than straight tooth bevels as there is gradual load applicationand low impact stresses. Of course, there exists an axial thrusts calling forstronger bearings and supporting assemblies these are used for the drive to thedifferential of an automobile.

Fig. 8

BearingA bearing is the machine element which supports another machine element(

known as journal). It permits a relative motion between the contact surfaces ofthe members, while carrying the load. Due to the relative motion between thecontact surfaces, a certain amount of power is wasted in overcoming thefrictional resistant and if the rubbing surfaces are in contact, there will berapid wear. In order to reduce frictional resistance and wear and in some casesto away the heat generated, a layer of fluid known as lubricant may be provided.The lubricant used to separate the journal and bearing is usually a mineral oilrefined from petroleum, but vegetable oils, silicon oils, greases etc may be used.

Classification of bearingsThough the bearing may be classified n many ways, yet the following areimportant from the subject point of view.1. Depending upon the direction of load to be supported;The bearing under this group are classified as:a) Radial bearing:



The load acts perpendicular to the direction of motion of the moving element asshown in following figure.

Fig. 9b) Thrust bearing:If load acts along the axis of rotation of the shaft, then the bearing whichsupports such shaft is called as thrust bearing.

Fig. 10

2. Depending upon the nature of contacta) Sliding contact bearing:

Sliding takes place along the surfaces of contact between the moving elementand the fixed element. They are also known as plain bearing. The sliding contactbearing are also known as journal bearing. They have surface contact withmoving element.

b) Rolling contact bearing;Rolling motion takes place along the surfaces of contact between the parts.Steel balls or rollers are interposed between the moving and fixed elements,which offer rolling friction. They are also known as antifriction bearings. Theyhave point or line contact with moving element.



Fig. 11



EXPERIMENT NO. 1

TITLE: VERIFICATION OF EFFECT OF INSULATING MATERIAL ONHEAT TRANSFER

Aim: - Experimental Verification of effect of insulating material on heattransfer.Apparatus: Metal rod apparatus, Electric heater, Cu rod, Thermocouples

Theory: - Insulating materials: The material of low coefficient of thermalconductivity are called insulating material.The material which retards the flow of heat with responsible effectiveness isknown as insulation.Insulation serves the following purpose

1. It prevents the heat flow from system to surrounding.2. It prevents heat flow from surrounding to the system.

Desirable properties:1. It is able to withstand high or low temperature2. It should have long life and could withstand rough handling3. It must be easy to apply.4. It is economical

Applications:1. boilers and steam pipes2. Air conditioning systems3. food prevent stores and refrigerators4. Insulating bricks5. preservation of liquid gases

Experimental set up:It consists of metal rod which is insulated all over its structure with layer

of insulating material. An electric coil is fixed to one end of rod while other rodends in water. A number of thermocouples are fitted along the length of rod.Thermocouples are fitted along to measure temperature of inside insulation andwater inlet and outlet.

Control panel consist of temperature indicator with selector switch. Avoltmeter and n ammeter is provided to measure voltage and current supplied to



the water heater. Dimmerstat is provided to the control voltage supply toheater.

Procedure;1. Switch on the main switch2. Adjust the dimmerstat to give required heat input to the metal rod ( in

the range of 80 v to 120v).



3. Circulate sufficient amount of water through water jacket4. Take the reading of on interval 5 min. till steady state reached.5. Note down the temperature reading (T1 to T10)

Observation table:

Sr. no. Thermocouple Temperature30 35 40 45 50 55 60 65 70 75 80

Precautions:1. See the dimmerstat is at zero position before switching on the main switch2. Operate the temperature change over switch gently.3. Be sure that steady state is reached before taking to find readings.

Conclusion: As the rate of heat transfer decreases in insulating material, it isverify that insulating material resist the heat flow.



EXPERIMENT NO. 4

TITLE: DEMONSTRATION OF TWO STROKE AND FOUR STROKEENGINE

Aim: - To study working of Two stroke and Four Stroke Engine

Theory: - Any machine which derives heat energy from the combustion of fuel& converts part of this energy into mechanical work is known as heat engine.Heat engines are divided into two groups

1) Internal combustion Engine2) External combustion Engine

Internal combustion Engine External combustion Engine

1) Combustion takes place insidecylinder

Combustion takes place outsidecylinder

2)

Fuel combustion in presence ofair takes place inside cylinder &products of combustion acts onpiston to develop power

Heat of combustion istransferred to working fluidoutside cylinder & then fluid isexpanded to develop power

3) Eg. Diesel & Petrol engine Eg. Steam engines & Turbines

Depending upon cycle of operations IC engines are classified as

Two Stroke Engine Four Stroke EngineOne power stroke in One rotation ofcrank

One power stroke in Two rotations ofcrank

So we have types of IC engines as follows1) Four stroke SI engine2) Four stroke CI engine3) Two stroke SI engine4) Two stroke CI engine

Where SI engine ═ Spark ignition = Petrol engineCI engine = Compression ignition = Diesel engine



1] Four Stroke SI engine:The working cycle of the engine is completed four stroke or Two revolutions ofcrank & Petrol is used as fuel.

1) Suction Stroke: The piston is at the Top most position (TDC) and is readyto move down drawing the mixture of air & fuel. The inlet valve is open &exhaust valve is closed. As the piston moves downwards the fresh charge of airfuel mixture enters the cylinder through the inlet valve due to suction created.This continues until piston reaches the Bottom dead centre (BDC). At thisposition the inlet value closes. This downward movement of piston is known assuction stroke & crank rotates by 180° during this period.2) Compression Stroke: During this stroke both valves ( inlet & exhaust ) areclosed & the piston moves upward & compresses the charge enclosed in thecylinder. The pressure & temperature of the mixture increases continuouslyduring this process. As the piston reaches the TDC position, the mixture isignited by an electric spark.3) Power or Expansion stroke: The increased pressure of the mixture exertsa large force & pushes the piston down. During expansion stroke both valvesremains closed. The high pressure & temperature gases pushes pistondownwards “& gas pressure gradually decreases. Piston moves from TDC to BDC.As work is done this is called power stroke. Exhaust valve opens as pistonreaches to BDC. Pressure falls down to atmospheric pressure.4) Exhaust stroke: Now piston moves upward from BDC to TDC. Exhaust valveis open & inlet valve is closed. Moving piston pushes out the burnt gases throughexhaust valve. As piston reaches TDC, again the inlet valve opens & freshcharge is taken during next suction stroke.



The engine is known as four stroke engine because one power stroke in everyfour strokes of the piston.

2] Four Stroke CI Engine:The working cycle of the engine is completed in four stroke & diesel oil is

used as a fuel therefore it is known as four stroke diesel engine.1) Suction Stroke: The piston is at the Top most position (TDC) and is ready

to move down drawing only air. The inlet valve is open & exhaust valve isclosed. As the piston moves downwards, the air enters the cylinder through theinlet valve due to suction created. This continues until piston reaches theBottom dead centre (BDC). At this position the inlet value closes. Thisdownward movement of piston is known as suction stroke & crank rotates by180° during this period.

2) Compression Stroke: During this stroke both valves (inlet & exhaust) areclosed & the piston moves upward & compresses the air enclosed in the cylinder.The pressure & temperature increases continuously during this process. As thepiston reaches the TDC position, the mixture is ignited by an electric spark.

3) Expansion Stroke: During this inlet & exhaust valve are closed & fuelvalve opens just before beginning of third stroke. Because of temperature ofair at compression stroke, fuel is ignited & combustion takes place. Highpressure & temp. Gases pushes piston down .Exhaust valve opens as pistonreaches BDC.

4) Exhaust stroke: During this inlet & fuel valve remain closed, exhaust valveremains open. Piston moves from BDC to TDC & pushes out burnt gases.

3] Two Stroke engine:The working cycle of the engine is completed Two stroke or One revolutions ofcrank.

1) Initially piston is at TDC & as it moves downwards to BDC, exhaust portgets opened & burnt gases moves downwards. With further downwardmovement inlet port is opened & suction takes place , air fuel mixture isadmitted in crank case. Further downward movement of piston givescompression stroke for fresh charge & now piston is at BDC.

2) Now while moving piston from BDC to TDC upwards, the charge iscompressed again & spark plug gives spark to initiate combustion.Combustion developes fully when piston is at TDC. Due to high pressure &temp. Piston is pushed downward.



Conclusion:-

References:



EXPERIMENT NO. 5

TITLE: Study of Package Type Boilers

Aim: - To Study of Package Type Boilers

Theory: - A steam generator known as boiler is a closed vessel made of high qualitysteel in which steam is generated by water by the application of heat. The waterreceives heat from hot gases through the heating surface of boiler. The hot gases areformed by burning fuel may be coal, oil or gas. The steam which is collected under thewater surface is taken from boiler through super heater & then suitable pipes fordriving engines or turbines. A boiler consists of not only the steam generators but alsoa number of parts to help for safe & sufficient operation of system as a whole. Theseparts are called mountings & accessories.

Classification of Boilers:

1) According to relative position of water & hot gases :i) Fire tube ii) Water tube2) According to axis of shell : i) Vertical boiler ii) Horizontal boiler3) According to method of furnace : i) Externally fired ii) Internally fired4) According to method of water circulation : i) Natural air ii) Forced air5) According to use : i) Stationary boiler ii) Mobile boiler6) Boilers which are factory assembled & mounted on skids and are ready for

operation once water & steam lines are connected are known as Package Boilers.

Requirements of Good Boiler:

A good boiler must posses following qualities:1) The boiler should be capable to generate steam at the required pressure andquantity as quick as possible with minimum fuel consumption.2) The initial cost, installation cost and the maintenance cost should be as low aspossible.3) The boiler should be light in weight, and should occupy small floor area.4) The boiler must be able to meet the fluctuating demands without fluctuations.5) All the parts of the boiler should be easily approachable for cleaning and inspection.6) The boiler should have minimum of joints to avoid leaks which may occur due toexpansion and contraction.7) The boiler should be erected at site within a reasonable time and with minimumlabour.8) The water and flue gas velocities should be high for high heat transfer rates withminimum pressure drop through the system.



9) There should be no deposition of mud and foreign materials on the inside surfaceand soot deposition on the outer surface of heat transferring parts.10) The boiler should conform to the safety regulations as laid down the boiler act.

Fig. 1Packaged Water Tube Boilers:

Capacity: 50 tons/hr with water cooled furnace

Advantages:i) Minimum weightii) Minimum maintenanceiii) Maximum structural rigidityiv) Maximum safety

Fuel used: Coal, wood, process waste

Fig shows Package boiler with feed pump, blower & other mountings provided. Air issupplied by blower & combustion of air & fuel takes place. As a result, hot highpressure gases are generated in combustion chamber & flow from front end to rearend, through central fire tube in Ist passThen the gases will flow from rear end to front end again through lower fire tube inIInd pass.Now in IIIrd pass, gases again flow from front end to rear end through upper firetubes& the exhausted through chimney.



EXPERIMENT NO. 6

TITLE: STUDY OF DOMESTIC REFRIGERATOR & WINDOW AIRCONDITIONER

Aim: - Study of Power transmitting element.Theory: - Refrigeration is defined as an art of producing and maintainingtemperature in a space below atmospheric temperature. A refrigerator is equipmentused to remove the heat continuously from space (Sink) & maintain the temperaturebelow atmospheric temperature and reject heat to the atmosphere (source).

Vapor Compression Refrigeration System:

In Vapor compression refrigeration system, the refrigerant used alternately undergoesa change of phase from vapor to liquid and liquid to vapor during the cycle. The latentheat of vaporization is utilized for absorbing the heat at low temperature from therefrigerated space. A constant temperature can be maintained in the space.

The arrangement of the components of vapor compression refrigeration systemis shown in fig. The liquid coming out from the condenser is passed through thethrottle valve (float valve). The pressure of the refrigerant is reduced as it passesthrough the throttle valve. The function of the throttle valve is to allow the liquidrefrigerant under high pressure to pass at a controlled rate into the low pressure partof the system known as evaporator. A mixture of vapor and liquid refrigerant entersthe evaporator (refrigerator) at low pressure. The liquid refrigerant absorbs the heatload on the refrigerator as its latent heat of evaporation is converted into vapor. Thefunction of the compressor is to increase the pressure of the refrigerant so that the



refrigerant vapor would be able to dissipate its latent heat to the atmosphere. Thehigh pressure, high temperature refrigerant vapor leaving the compressor enters intothe condenser where the latent heat of refrigerant is removed by circulating eitheratmospheric air or water. The liquid refrigerant leaving the condenser again enters thethrottle valve and the cycle is repeated.

Domestic Refrigerator:The basic components are

i) Evaporatorii) Compressoriii) Condenseriv) Expansion device

The evaporator where the refrigerant (working fluid) evaporates absorbs the latentheat of vaporization is the part of the freezer cabinet, where it is loaded. In modernfrost free refrigerators, the evaporator is located outside the cabinet, as fancirculates air from evaporator to the freezer. Just below the freezer, there is achiller tray. Further below are compartments with progressive higher temperature.The bottom most compartment means of vegetable is the cold one. The cold air beingheavier flows down from the freezer to the bottom of the refrigerator. The warm airbeing lighter flows upward from vegetable box to freezer gets cooled & flows downagain. Thus natural convection current is set up which maintains a temperature gradientbetween top & bottom of refrigerator. The temperature maintain in the freezer is -15°C . The condenser is usually a wire & tube type mounted at the back of therefrigerator. Having no fan, the refrigerator vapor is condensed with the help ofsurrounding air which rises above by natural convection as it gets heated afterabsorbing the latent heat of condensation from refrigerant. After condensation, thehigh pressure liquid refrigerant is reduced to the low pressure of the evaporator bypassing through liquid. Refrigerant is reduced to the low pressure of the evaporator bypassing through an expansion device (throttle) valve or capillary tube and cycle iscompleted.

Window Air Conditioning:Let us consider a room to be maintained at a constant temperature of 25°C. The

air from the atmosphere drawn by a fan & is made to pass over a cooling coil ofevaporation, the surface of which is maintained at a temperature of 10°C.

After passing over the coil, the air is cooled to around 10°C before beingsupplied to the room at 25°C by the fan. In the cooling coil, the refrigerant R-22 or R-134 enters at say 5°C & evaporator absorbing the latent heat of vaporization from theroom air.

The refrigerator from the evaporator is compressed to high pressure beforeentering the condenser where the atmospheric air at about say 45°C in summer is



circulating by a fan. After picking up the latent heat of condensation from therefrigerant, the air is thrown back to the atmosphere say at 55°C. The high pressureliquid refrigerant from the condenser is reduced to the low evaporator pressure bypassing through the expansion device (capillary tube) before entering the evaporator.The cycle repeats itself.

BASICS OF MECHANIACAL ENGINEERING – LABORATORY MANUAL


EXPERIMENT NO 7

TITLE: DEMONSTRATION OF OPERATIONS ON CENTRE LATHE

APPARATUS: lathe machine and mild steel rod.

OBJECTIVE: To study the various operations such as turning, step turning,facing, boring, taper turning, knurling, grooving, threading of center lathe.

THEORY: A product is made up of many components which are manufacturedby various manufacturing processes such as casting, forging, welding; machiningetc depends on the application and cost of that particular component. In themachining process various operations comes like turning, step turning, facing,boring, taper turning, knurling, grooving, threading. All these operations can bedone on center lathe hence center lathe is one of the importance type ofmachines. In this practical we are going to study the operations which arementioned above.Lathe is a machine tool which rotates the work piece on its axis to performvarious operations such as cutting, sanding, knurling, drilling or deformation withtools that are applied to the work piece to create an object whichhas symmetry about an axis of rotation. Examples of objects that can beproduced on a lathe include candlestick holders, gun barrels, sticks,table legs, bowls, baseball bats, musical instruments (especially woodwindinstruments), crankshafts and camshafts.Parts of lathe and their functionBed: Almost all lathes have a horizontal beam is called as bed. It has guide wayson it for sliding and supporting tail stock and carriage.Head stock: At one end of the bed (almost always the left, as the operatorfaces the lathe) is a headstock. It contains drive mechanism with necessaryspeed change arrangement to achieve different speeds. It also has chuck whichis used to hold the job.Tail stock: It is places opposite to headstock. It can move along guide ways. Itsmain applications are to hold long jobs to avoid vibrations and excessivedeformation and for drilling axial holes in the work piece it can also hold thetools such as drill, reamer, tap to do the operations like drilling, reaming etc.Carriage: It is located between head stock and tail stock. It can be moved inlongitudinal direction and can be fixed at any position. Carriage has followingpartsa. Saddle: Its base portion, located across lathe bed and carries cross slide andtool post, it can be moved longitudinally along the bed.b. Apron: it is attached to saddle and appears as hanging on front side. Itconsists of gears for motion transmission.



C: Cross slide: it is mounted on top of the saddle and acts as support tocompound restD: Compound rest: It is mounted on cross slide and it consists of swivel and topslide. The tool post is mounted on top slide.E: Tool-post: it is used to hold the tool position the tool as per the requirement.

Fig.: Schematic Illustration of center lathe

Various Lathe operations

Turning: It is the process of removing the material fromextended surface of rotating work piece. So it is theprocess by which a piece of material (wood, metal, plastic,or stone) is rotated and a cutting tool is traversed along 2axes of motion to produce precise diameters and depths

Fig: Turning



Step Turning: It is the process of obtaining different diameters on a workpiece along the length by adjusting depth of the tool

Fig: Step Turning

Taper Turning: It is the process of giving the angle to the work piece with thehelp of compound slide.

Fig: Taper turning



Boring: It is the machining of internal cylindrical forms (generating) a) bymounting work piece to the spindle via a chuck or faceplate b) by mounting workpiece onto the cross slide and placing cutting tool into the chuck.

Fig: Boring operation

Knurling: The cutting of a serrated pattern onto the surface of a part to use asA hand grip using a special purpose knurling tool

Fig. Knurling Tool

Threading: It is the process of producing the helical V grooves on the surfacewith the help of lead screw.

Fig: Threading Process.



FacingIt is the process of removing the material from the end surface or face of workpiece.

Fig: Facing

Grooving: It is the process of producing V shape cyclical groove on the surface,the tool has similar V shape as required to produce on work piece

Fig. Grooving

CONCLUSION:Hence we have studied various operations such as turning, step turning, facing,boring, taper turning, knurling, grooving, and threading which are performed oncenter lathe.REFERENCES:

1. Elements of Workshop Technology (Vols. 1 and II) by Hajra chaudhary



EXPERIMENT NO 8

DEMONSTRATION OF OPERATIONS ON DRILLING MACHINES

APPARATUS: Drilling machine and mild steel rod.

OBJECTIVE: To study the various operations on drilling machines such asdrilling, reaming, spot facing , counter boring

THEORY: Holes in the work piece are necessary for many purposes such asfastening the object with nuts and bolts, Screws, for fixing assembly purposeSo it is necessary to make holes in the work piece. So the Drilling is a process ofmaking a hole in the blank work piece, or enlarging the existing hole. TheMachine which is used foe this purpose is called as drilling machine.It consist of spindle which is rotated by the motor and transmitting mechanism,The spindle in turn rotates the drilling tool called as drill, as drill is press fittedinto the spindle. Drill is fed into work by feed mechanism. The work piece isfixed on the table, as the drill fed into the work piece, the hole is created byremoving material in the form of chips. All the components are supported byframe. Cutting fluid is commonly used to cool the drill bit, increase tool life,increase speeds and feeds, increase the surface finish, and aid in ejectingchips.

Fig: Drilling machine



Parts of Drilling machine and their functionBase: base is the lowest horizontal part which supports the entire structure ofdrilling machine. It is made up of cast iron because cast iron absorbs vibrations.So the vibrations transmitted to foundation get reducedWork table: It is mounted on column which supports the work. Generally its hastwo types of motionsa. It can swing about columnb. it can move up and down. This facilitates the positioning of work piece whiledrilling.Spindle: It is a hollow portion which is provided with rotary motion spindleimparts this rotator motion to drill.Head: It consist of drive mechanism and feed mechanism.

Operations Performed on the drilling machineDrilling: It is the process of making a hole in blank work piece with tool known asdrill.

Fig: DrillingReaming: It is process of finishing and sizing of drilled hole with the help oftool called as reamer.

Fig: Reaming



Boring: It is process of enlarging the already existing hole to meet the requiredSize and finish.

Fig: BoringSpot facing: It is the process of machining a flat circular surface around a holeto provide a seat for a bolt head nut or washer.

Fig: Spot facing

Counter boring: It is the process of cylindrically enlarging the face of existinghole.

Fig: counter boring



CONCLUSION:Hence we studied various operations such as drilling, reaming, spot facing,counter boring which are performed on Drilling machine.REFERENCES:

1. Elements of Workshop Technology (Vols. 1 and II) by Hajra chaudhary

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