FLANGED COUPLING What is coupling? •
A device that is used to connect two shafts together for the purpose of power transmission.
General types of couplings: •
Rigid: for aligned shafts
•
Flexible: for non-aligned shaft
Rigid couplings: Rigid couplings are aligned shaft couplings that are designed to draw two shafts together so that no motion can occur between them
Types of rigid couplings: 1-Flanged
2-Sleeve/Muff 2-Sleeve/Muff Coupling
3-Clamp/Split muff/Compression Coupling
Flexible couplings: i. Used Used to to join join shaf shafts ts tha thatt mee meett at at a sli sligh ghtt angl angle. e. ii. Angle Angle may still still chang change e whil while e runni running ng due due to vibrat vibration ion or load.
Types of flexible couplings: 1-Universal Coupling2-Bushed Coupling2-Bushed Pin Type Coupling
3-Olbham Coupling
Flanged Coupling: Flange: A flange is defined as a plate type device, normally round, that is attached to the end of a pipe, fitting, valve or other object to facilitate the assembly and disassembly of a piping system.
Flange coupling:Each flange is mounted on the shaft and keyed to it. Faces are turned up at right angle to the axis of the shafts. One of the flange has a projected portion and other has a corresponding recess. Two flanges are coupled together by bolts and nuts.
Types of flange couplings:
1-Protected type flange coupling 2-Unprotected type flange coupling 3-Marine type flange coupling
Unprotected type flange coupling: In this type of flange coupling each shaft is keyed to the boss of a flange with a counter sunk key and the flanges are coupled together by means of bolts (Generally 3,4,6 bolts are used.)Keys are staggered at right angle along the circumference of the shafts in order to divide weakening effect caused by key ways.
Unprotected type flange coupling:
The usual proportions for an unprotected type cast iron flange couplings, are shown as follows:
Let d = Diameter of shaft or inner diameter of hub, D = Outer diameter of hub,
d 1 = Nominal or outside diameter of bolt, D 1 = Diameter of bolt circle, n = Number of bolts, tf = Thickness of flange,
τs , τb, τk = Allowable shear stress for shaft, bolt and key material respectively τc = Allowable shear stress for the flange material i.e . cast iron, cb , and σ ck ck = Allowable crushing stress for bolt and key σ cb
material respectively
1-Design for hub: The hub is designed by considering it as a hollow shaft, transmitting the same torque (T) as that of a solid shaft. T=3.14/16×τc(D^4-d^4/D) Here D=2d and L=1.5d
2-Design for key: The key is designed with usual proportions and then checked for shearing and crushing stresses. The material of key is usually the same as that of shaft. The length of key is taken equal to the length of hub.
3-Design for flange: The flange at the junction of the hub is under shear while transmitting the torque. Therefore the torque transmitted, T= Circumference of hub × Thickness of flange × Shear stress of shaft ×Radius of hub =3.14D×tf×τc×d/2=3.14D^2/2×τc×tf Here
tf=1.5d
Therefore from the above relation, the induced shearing stress in the flange may be checked.
4-Design for bolts:
The bolts are subjected to shear stress due to the torque transmitted. transmitted. The number of bolts (n)depends upon the diameter of shaft. And D1=3, load on each each bolt=3.14/4×(d1)^2 bolt=3.14/4×(d1)^2 τb Total load on all all the bolts=3.14/4(d1)^2 τb×n And torque is transmitted T=3.14/4(d1)^2τb×n×D/2 From this equation, the diameter of bolt (d1) may be obtained. Now, the diameter of bolt may checked in crushing. Area resisting crushing of all the bolts =n×d1×tf And crushing stress for all the bolts =( n×d1×tf) σcb Torque, T=( n×d1×tf×σcb)D1/2 n×d1×tf×σcb)D1/2 From this equation, the induced crushing stress in the bolts may be checked.
CALCULATIONS: Statement: Design flange coupling with diameter of shaft 60mm and material of shaft is high carbon steel, material of key, coupling and bolt is low carbon steel with factor of safety 2. Data: d = 50mm For high carbon steel Sy = 380 MPa For low carbon steel Sy = 300 MPa FOS = 2 Solution: For shaft:
Τ all = 0.4 Sy =0.4×380 = 152 MPa Σ all = 0.9 Sy = 0.9×380 = 342 MPa nf = T all/ Td Td = 152/2 = 76 MPa Tmax = pi/16 d3 Td =pi/16 (0.06) 76= 3221.64 Nm
For hub, key,bolts,:
tall = 0.4 Sy = 0.4×300 = 120 MPa σall = 0.9 Sy = 0.9×300 = 270 MPa nf = tall/td td = tall/ nf = 120/2 = 60 MPa σd = σall/ nf = 270/2 = 135 MPa 1-Design of hub:
D = 2d = 2×60 = 120mm L = 1.5d = 1. ×560 =90mm T = pi/16 tc[D^4 – d^4] / D 3221640 = pi/16 tc (120^4 – 60^4 )/ 120 tc = 10.13 MPa<60MPa which is designed stress so design is safe here. 2-Design of key:
w= d/4 = 60/4 = 15 mm t = d/6 = 60/6 = 10mm l = 1.5d = 1.5×60 = 90m Shear of the key:
T = tk×w×l(d/2)w
tk = T/w×l× (d/2) = 3221640/ 15×90×30=79.54 Mpa Crushing of the key:
σ ck ck = 2T/ t×l× (d/2) = 6443280/ 27000 = 238.64 MPa 3-Design for flange:
tf = 0.5 d=30mm Resistive area=piD T=tc.pid^2/2.tf , tc =2T/piD^2tf=4.75MPa =2T/piD^2tf=4.75MPa While for flange: td=60MPa
It means the actual shear stress(4.75MPa) in flange is less than designed(60MPa)so our design is in safe range.
4-Design for bolts: D1=3d=3(60)
=180mm T=tb×pi/4×db^2×n×D1/2 db^2=8T/tb.pi.n.D1/2 db =19.49mm From Market point of view 22mm or 22M. Now, T=σcb×n×(db×tf)×D1/2 σcb = 2T/n.db.tf.D1 =13.55 MPa<135MPa which is designed stress so design is safe.
Objective
• The objective of this project is to
design and fabricate a Bushed-pin type flexible coupling. coupling. •
Its function is to transmit power betw betwee een n sh shaf afts ts that that are are part partia iall lly y misaligned
and
it
also
absorbs
shock loads. •
It empl employ oys s rubb rubber er bush bushes es fi fitt tted ed over pins that transmit torque by means of shear resistance.
•
Design will be carried out by choosing a prime mover having an
output of 5000 W and a speed of 750 rpm.
PHOTOGRAPHIC VIEWS OF THE COUPLING
AUTOCAD DIAGRAM OF THE COUPLING
LIST OF COMPONENTS USED • INPUT FLANGE
: It is keyed to the input shaft coming from the prime mover and transmits power to the pins through the rubber bush.
• OUTPUT FLANGE : It obtains obtains power from the pins by means of shear resistance, is keyed to the output shaft.
•
PINS
: The pins here are nothing but unthreaded bolts.
They connect the two flanges and also maintain a clearance between the two shafts shafts for angular misalignment.
•
RUBBER BUSHES : These rubber bushes are provided to absorb shock loads, torsional vibrations and angular misalignments. They are provided with brass linings to reduce wear.
INPUT FLANGE
OUTPUT FLANGE
PINS
RUBBER BUSHES
DESIGN OUTPUT DIAGRAM DRAWN USING AUTOCAD
DESIGN OUTPUT PARAMETERS • SHAFT DIAMETER
:
16mm
•
OUTER FLANGE DIAMETER :
100 mm
•
HUB DIAMETER
•
PCD of PINS
•
LENGTH OF HUB
:
30mm
•
PIN DIAMETER
:
10mm
:
30mm :
63mm
•
LENGTH OF BUSH
•
PROTECTIVE LAYER
: :
20mm 12mm
THICKNESS •
NUMBER OF PINS
•
DIAMETER OF BUSH
•
CLEARANCE
: :
4 22mm
:
2mm
ADVANTAGES
• It can tolerate 0.5mm of lateral or axial misalignment and 1.5 degrees of angular misalignment. •
Prevents transmission of shock from one shaft to the other and absorbs vibrations.
•
It can be used for transmitting high torques.
•
It is simple in construction and easy to assemble and dismantle.
•
It is easy to design and manufacture the coupling.
•
For the same size of shafts, flexible bush coupling has larger number of bolts or
larger pitch circle diameter than rigid type coupling. This reduces the force acting on the pins and lowers bearing pressure on the rubber bush.
DISADVANTAGES
• The cost of flexible coupling is more than that of rigid coupling due to additional parts. •
It requires more radial space compared with other types of coupling.
•
Maximum allowable peripheral speed of the coupling is 30m/s.
Design of shaft coupling • Shafts are usually available up to 7 meters length due to inconvenience in transport. • In order to have a greater length, it becomes necessary to join two or more pieces of the shaft by means of a coupling
• Shaft couplings are used in machinery for several purposes, • 1.To provide for the connection of shafts of units that are manufactured separately such as a motor and generator and to provide for disconnection for repairs or alternations. • 2.To provide for misalignment of the shafts or to introduce mechanical flexibility. • 3.To reduce the transmission of shock loads from one shaft to another. • 4.To introduce protection against overloads. • 5.It should have no projecting parts
• Requirements of a Good Shaft Coupling • 1.It should be easy to connect or disconnect. • 2. It should transmit the full power from one shaft to the other shaft without losses. • 3.It should hold the shafts in perfect alignment. • 4.It should reduce the transmission of shock loads from one shaft to another shaft. • 5.If should have no projecting parts.
Types of Shafts Couplings • 1. Rigid Rigid coupli coupling ng
2. Flexib Flexible le coupli coupling ng
1. Rigid couplin coupling g : It is used to connect connect two shafts which which are perfectly aligned. • type types s of rigi rigid d coup coupliling ng are are • a)Sl a)Slee eeve ve or muff muff coup coupliling ng.. • b)Clam b)Clamp p or spli split-m t-muff uff or or compre compressi ssion on coupl coupling ing,, • c)Fl )Flange ange coup oupling ling
• 2.Fl 2.Flex exib ible le coupl couplin ing g : It is used used to conn connec ectt two two shaf shafts ts having both lateral and angular misalignment. • Type Types s of of fle flexi xibl ble e coup coupliling ng are are • a)Bu a)Bush shed ed pin pin typ type e cou coupl plin ing, g, • b)Un b)Univ iver ersa sall coup coupli ling ng,, and and • c)Ol )Oldham dham cou couplin pling g
a. Sleeve or Muff-coupling
• It is the the simpl simples estt type type of rigid rigid coupl couplin ing, g, made made of cast cast iron. • It consi consist sts s of a hollow hollow cylin cylinde derr whose whose inner inner diame diamete ter r is the same as that of the shaft (sleeve). • It is fitt fitted ed over over the the ends ends of the two two shaft shafts s by mean means s of a gib head key, key, as shown in Fig.
• The The powe powerr is tran transm smit itte ted d from from one one shaft to the other shaft by means of a key and a sleeve.
• SHAFT - (d, T) d = diameter of the shaft , T= torque • SLEEVE – (D, L) D= Outer diameter of the sleeve • KEY- RED • l= length, w= width, t=thickness
1. Design for sleeve
• The usual proportions of a cast iron sleeve coupling • Oute Outerr dia diame mete terr of of the the slee sleeve ve,, D =2d + 13 mm
• lengt ength h of of the the sleev eeve, L=3.5d Where d = diameter of the shaft
• The sleeve is designed by considering it as a hollow shaft. • T=Torque to be transmitted by the coupling • τc=Per =Permi miss ssib ible le shea shearr stre stress ss for for the the mate materi rial al of the the sleeve which is cast rion. • τc = 14 MPa. • Torque Torque transm transmitt itted ed by by a hollow hollow sectio section n T = (π/16)×τc×(D4-d4)/D = (π/16)×τc×D3(1-K4) ... (∵k = d / D) • From From this this expre xpress ssiion, on, the the ind induced uced shear stress in the sleeve may be checked
2. Design for key • The The lengt length h of the cou coupl plin ing g key = leng length th of the the sleev sleeve e ( i.e. . 3.5d ). • The coupli coupling ng key key is is usual usually ly made made into into two two parts parts • leng length th of the the key key in each each shaf shaftt l= L/2=3.5d/2
• After fixing the length of key in each shaft, the induced shearin ring and crus rushing stresses may be checked. We know that torque transmitted,
• T = l× w×τ ×(d /2) (Considering shearing of the key) • T = l × t/2 × σ C × (d /2) (Considering crushing of the key
b. Clamp or Compression Coupling
• the the muff uff or sle sleeve eve is made ade into into two two hal halves and and are bolted together. • The halves halves of the the muff muff are made made of cast cast iron. iron. • The shaft shaft ends ends are made made to a butt butt each each other other • a sing single le key key is fitt fitted ed dire direct ctly ly in the keyw keyway ays s of both both the shafts. • One-ha One-half lf of the the muff muff is fix fixed ed from from below below and and the the other other half is placed from above.
• Both Both the the halv halves es are are held held toge togeth ther er by means means of mild mild steel studs or bolts and nuts. • The number number of bolt bolts s may may be be two, two, four four or six. six. • The The advan advanta tage ge of this this coupl couplin ing g is that the the posit positio ion n of the shafts need not be changed for assembling or disassembling of the couplings
1. Design of muff
• The usual proportions of a cast iron sleeve coupling • Oute Outerr dia diame mete terr of of the the slee sleeve ve,, D =2d + 13 mm
• lengt ength h of of the the sleev eeve, L=3.5d Where d = diameter of the shaft • The sleeve is designed by considering it as a hollow shaft.
• T=Torque to be transmitted by the coupling
• τc=Per =Permi miss ssib ible le shea shearr stre stress ss for for the the mate materi rial al of the the sleeve which is cast iron. • τc = 14 MPa. • Torque Torque transm transmitt itted ed by by a hollow hollow sectio section n T = (π/16)×τc×(D4-d4)/D = (π/16)×τc×D3(1-K4) ... (∵k = d / D) • From From this this expre xpress ssiion, on, the the ind induced uced shear stress in the sleeve may be checked
2. Design for key • The The lengt length h of the cou coupl plin ing g key = leng length th of the the sleev sleeve e ( i.e. . 3.5d ). • The coupli coupling ng key key is is usual usually ly made made into into two two parts parts • leng length th of the the key key in each each shaf shaftt l= L/2=3.5d/2 • After fixing the length of key in each shaft, the induced shearin ring and crus rushing stresses may be checked. We know that torque transmitted
• T = l× w×τ ×(d /2) (Considering shearing of the key) • T = l × t/2 × σ C × (d /2) (Considering crushing of the key
3. Design of clamping bolts
• T =Tor =Torqu que e tran transm smit ited ed by by the the sha shaft ft,, • d =Di =Diam amet eter er of sha shaft ft,,
• d b=Root or effective diameter of bolt • n=Nu n=Num mber ber of bolts olts,, • σt =Permissible tensile stress for bolt material, • µ= µ=Co Coef effi fici cien entt of frict frictio ion n betw betwee een n the the muff muff and shaft shaft,, and • L=Le L=Len ngth gth of muff muff..
• forc force e exe exert rted ed by by eac each h bol boltt (F) =(π/4) (d b2 ) σt • Forc Force e exer exerte ted d by the the bolt bolts s on each each side side of the shaf shaftt (F)= (π/4) (d b2 ) (σt )(n/2) • (P )be )be the the pressu pressure re on the shaf shaftt and the the muff muff surfa surface ce due to the force, then for uniform pressure distribution over the surface • P=Fo P=Forc rce/ e/Pr Proj ojec ecte ted d area area • P= (π/4) (d b2 ) (σt )(n/2)/(1/2)Ld
• ∴Frictional force between each shaft and muff, F =µ× pressure × area • F=(µ × (π/4)(d b2 )(σt )(n/2)/(1/2)Ld ) × π (1/2) d L
• F= µ × (π2 /8)(d b2 )(σt )(n)
• Torque Torque that that can can be tran transm smitt itted ed by by the the coupl coupling ing T=F × d/2 T=µ × (π2 /8)(d b2 )(σt )(n)×d/2 • From this relation, the root diameter of the bolt (d b ) may be evaluated .
µ=0.3
c. Flange coupling
• A flange flange coup couplin ling g usuall usually y applie applies s to a coupl coupling ing havi having ng two separate cast iron flanges. • Each Each flang flange e is moun mounted ted on on the shaf shaftt end end and keye keyed d to it. • The faces are turned up at right angle to the axis of the shaft • Flan Flange ge coup oupling ling are are • 1.Un 1.Unpr prot otec ecte ted d type type flang flange e coupl couplin ing g • 2. Pro Prote tect cted ed typ type e flan flange ge cou coupl plin ing g • 3. Mari Marine ne type type flan flange ge coup coupliling ng
Conclusion:
Coupling designed according to the above considerations will be more suitable, but the modifications according to our needs can also be made for more better results.
AUTOMOBILE SHOP EQUIPMENT As good workshop must have equipped undertake all types of fault finding finding and Servicing Servicing jobs. The following following is a list of tools and equipment which are must in the workshop:1. Screw Screw drivers. drivers. 2. Spanners, Wrenches etc. 3. Pl Plier iers. s. 4. Hamm Hammer er 5. Chisel Chisel 6. Files Files 7. Hack Hack saw saw 8. Drilling Drilling machine machine 9. Bench Bench vice vice 10.Grinder 11.Measuring tools 12.Chain pulley block 13.Hydraulic jack and axle stands 14.Creeper 15.lubrication equipment 16.Battery testing and charging. 17.Electric equipment.
18.hydraulic lilt 19.Tools for treys . 20.Tyre remover 21.wheel balancing equipment 22.brake testing 23.high 23. high pressure washing washing equipment 24.Engine analyzer. 25.Air 25. Air compressor compressor and pressure gauge. 26.workshop 26. workshop manuals manuals for popular vehicle 27.Hydraulic press. 28.Piston 28. Piston ring compressor. compressor. 29.Ring remover. 30.ring fitting tool 31.Piston 31. Piston grooves cleaner. cleaner. 32.Cylinder 32. Cylinder boring machine. machine. 33.cylinder 33. cylinder boring machine 34.Valve facing machine. 35.Valve seat grinding equipment. 36.Chassis 36. Chassis alignment alignment equipment. 37.Spark 37. Spark plug testing and cleaning machine. machine. 38.Steering 38. Steering geometry and alignment alignment machine . 39.Connecting 39. Connecting rod alignment alignment machine. 40.Nozzle 40. Nozzle testing and cleaning equipment. equipment.
41.Fuel injector tester. 42.Centre lathe. 43. Fire extinguisher. 44.Electric welding set.
