2 chain drives
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ME‐205 : Element of machine dynamics and design
Dr. Muhammad WasifAssistant Professor – I.M.D.
Ph.D. (CAD/CAM – Canada), M.Engg. (Mfg. Engg. – NEDUET), B.E. (Mech. Engg. – NED UET). Member ASME and PEC
Room : 1st on LHS of main corridor, ground floor – IM Building
Machine dynamics : Chain Drives
1
Chain Drives• Roller chain is mostly used to transmit power.
• A chain is a power transmission element made
as a series of pin‐connected links.
• Load is applied by the driving sprocket on the
chain, the load is transmitted to a bushing, pin,
and pair of link plates, pins and link plates push
the driven sprocket to run.
2ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives
3ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives ‐ Advantages• Due to no slippage, constant velocity is obtained.
• Less width is occupied, due to metal strength.
• Can be used for short as well as long center distances.
• High transmission efficiency (97‐99%).
• One chain can transfer power to multiple shafts.
• Can be operated at high temperature.
• Permits high speed ratio of 8 to 10.
• Multiple reduction stages are made, for high reduction ratio.4ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives ‐ Limitations• Installation and component cost is higher.
• Require maintenance and lubrication.
• Velocity fluctuation occurs, when mounted inaccurately.
5ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives – Roller chainsRoller dia (d)
b1
6ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives ‐ Nomenclature• Pitch
Is the distance between the centers of two adjacent pins.
• Pitch circle radius (rc)
Distance between the pin
center and the center of
sprocket, when the hinge
is meshed with that
sprocket.
7ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives ‐ Classification• Hoisting and hauling (or crane) chains
‐ Can be used up to 0.25m/s‐ Two types : Oval and square links
• Conveyor Chains‐ Used for elevating and conveying within 0.8 to 3m/s.‐ Two types : Detachable or hook joint, closed joint type.
8ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives ‐ Classification• Power Transmitting Chains‐ Used for short center distance.‐ Three types :‐ Block or bush chain‐ Bush roller chain‐ Silent chain
9ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives – Lubrication• The performance of chain assembly is improved by
proper lubrication. It reduces the friction and act as
a coolant.
• Improper lubrication produces premature chain
failure.
• Lubrication types depend upon the speed and
environment.
10ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives – Lubrication• Manual lubrication : Lube is applied periodically
using brush or oil can. e.g. cycle or bike chain.
• Drip lubrication : oil drips with sufficient flow is
directed on the chain. e.g. Conveyor chains, engine.
11ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives – Lubrication• Bath or Disc lubrication : chain runs
through an oil sump or bath in the drive
housing. In disc lubrication, a disc picks
up the oil and deposit on chain. Oil
level is to be maintained in these cases.
• Stream lubrication : Some nozzles
attached with supply of oil, are set on
chain to spray the oil on chain near
sprocket engagement.
12ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Chain Drives – Roller chains
13ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Recommendations
• 17, 120
, = No. of teeth on small, large sprocket
• Velocity Ratio (V.R.) =n1 n2⁄ 7
• 30 pitches center distance (C) 50 pitches
• Pitch (p) should be even.
• Chain length (L)=2C ∙
14ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains – problem solving steps1. Specify a service factor and compute the design power.
Ks=K1.K2.K3 ; Pt=Ks x P
Multiple strand factor (1,2,3) ‐ Km=1.7, 2.5, 3.3 – Pt/Km15ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation2. Compute the velocity ratio. V.R. = n1/n23. Select the chain pitch, and rpm of smaller sprocket.
16ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation
17ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation4. Number of teeth of small sprocket.
5. Pitch of the chain
18
Roller chains ‐ Calculation
Roller dia (d)
b1
19ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation6. Compute number of teeth of larger sprocket.
T2 = T1 V.R (check in catalogue)
7. Compute the actual expected output speed
n2= n1 (T1/T2)
8. Compute the pitch diameters of the sprockets.
°⁄ °⁄
9. Compute the length of the chain (L).20ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation10. Corrected center distance.
14 ∙ 2 2 8 ∙ 2
11. Compute the angle of wrap of the chain for eachsprocket
180 ° 2. − /2
180 ° 2. − /2
21ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ CalculationDesign a chain drive for a heavily loaded coal conveyorto be driven by a gasoline engine through a mechanicaldrive. The input speed will be 900 rpm, and thedesired output speed is 230 to 240 rpm. The conveyorrequires 15.0 hp. (variable load with mild shock, 20 hr)
1. Ks=1.25(.8)(1.4)=1.4; Pt=Ks x P = 1.4 x 15 = 21hp
2. V.R. = n1/n2 = 900/235 = 3.83
3. Pt = 15hp = 21hp x 0.7456 kW/hp = 15.6576kW
22ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation3. Select the chain pitch, and rpm of smaller sprocket.
23ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation4. Number of teeth on sprockets.
5. Pitch
24
Roller chains ‐ Calculation6. T2= T1 x V.R = 23 x 3.83 = 88.09 89
7. n2= n1x(T1/T2) = 900(23/89) = 232.58 rpmRange given 230‐240 – OK
8. °⁄ = .
°⁄ 139.902mm
°⁄ = .
°⁄ 539.790mm
25ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation9. Length of the chain
C = 40pitch (30 to 50 is recommended)
L 2C ∙
L 138.757pitch 140 pitches (even recommended)L 140(19.05) 2667 mm
Corrected center distance
C ∙ 8 ∙
C 40.64 pitch
C = 40.64(19.05) = 774.248mm26ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation
10. Angle of wrap
180 ° 2. − /2 =175.114°
180 ° 2. − /2 184.885°
27ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Design summary
175.114°184.885°
774.240mm
139.902mm
539.790mm
ChainPitch : No. 12B, 19.05mm Length : 140pitches = 2667mmCenter distance : 774.24mm maximumSprockets : Single strand, No. 12B, 19.05mm pitchSmall : 23 teeth, D = 139.902mmLarge : 89 teeth, D = 539.790mmLubricationBath lubrication is recommended due to 1000 rpm, large sprocket dip in bath.
28ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Compact Redesign 1. Transmitted power (design for 3 strands) Km=3.3
Pt = 15.6576/3.3 = 4.745kW2. V.R. = 3.833. Chain selection
29
Roller chains ‐ Calculation4. Number of teeth on sprockets.
5. Pitch
30
Roller chains ‐ Calculation6. T2= T1 x V.R = 23 x 3.83 = 88.09 89
7. n2= n1x(T1/T2) = 900(23/89) = 232.58 rpmRange given 230‐240 – OK
8. °⁄ = .
°⁄ 93.268mm
°⁄ = .
°⁄ 359.860mm
31ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation9. Length of the chain
C = 35pitch (30 to 50 is recommended)
L 2C ∙
L 129.151pitch 130 pitches (even recommended)L 130(12.7) 1651mm
Corrected center distance
C ∙ 8 ∙
C 35.443 pitch
C = 35.443(12.7) = 450.137mm32ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Roller chains ‐ Calculation
10. Angle of wrap
180 ° 2. − /2 =171.592°
180 ° 2. − /2 188.408°
33ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Design summary
171.592°188.408°
450.137mm
93.268mm
359.860mm
ChainPitch : No. 08B, 12.7mm Length : 130pitches = 1651mm Center distance : 450.137mm maximum (41.86% reduced)Sprockets : three strand, No. 08B, 12.75mm pitchSmall : 23 teeth, D = 93.268mm (33.33% reduced)Large : 89 teeth, D = 359.860mm (33.33% reduced)LubricationBath lubrication is recommended due to 1000 rpm, large sprocket dip in bath.
34ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
Refernces
35
• R.S. Khurmi, G.K. Gupta, 2005, A text book of machine design, New Dehli‐ India, EURASIA PUBLISHING HOUSE.
• R. G. Budynass, J.K. Nisbett, 2005, Shigley’s Mechanical Engineering Deisgn, New York –USA, McGraw Hill.
• R. L. Mott, 2004, Machine Elements in Mechanical Design, USA, Pearson Prentice‐Hall.
• R. L. Norton, 1996, Machine design an integrated approach, NJ USA, Prentice‐Hall.• B. J. Hamrock, B. O. Jacobson, S. R. Schmid, 1999, Fundamental of Machine
Elements, New York –USA, McGraw‐Hill.• U. C. Jinbal, 2010, Machine Design, India, Pearson .• R. O. Parmley, 2005, Machine devices and components, USA, McGraw‐Hill.
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