25-08-2017, 09:32 PM
In the primary circuit of cooling circuit, sometimes Pump or Motor stops working and they have to be dismantled and displaced to check out the fault and do the needful to resume smooth functioning of cooling system. The available manual system involves human labour to displace the part which is an uphill task. Then they delivering lecture on Cooling system, told us that he is working on developing alternative to this system and motivated us to think on same lines. He made us aware about the short comings of this system and suggested us some possible modifications. Further they provided us technical Know-how about Chain Hoisting Arrangement. After lot many brain storming sessions by the team under the guidance of them We propose a mechanical system ( Drawing Attached ) that will reduce human effort and is economical as well. 1.Members under load ( that are vulnerable to failure ) have been designed and dimensions are taken with factor of safety 2. 2. This system has been designed taking endurance limit ( 500 Million Cycles) 3. The system provides three degrees of freedom al
Project report:
Design of a Mono-Rail Attachment for Primary Cooling Water Pumps and Motors.
Introduction :- In the primary circuit of cooling circuit, sometimes Pump or Motor stops working and they have to be dismantled and displaced to check out the fault and do the needful to resume smooth functioning of cooling system. The available manual system involves human labour to displace the part which is an uphill task.
Mr. Pradeep Kumar, while delivering lecture on Cooling system, told us that he is working on developing alternative to this system and motivated us to think on same lines. He made us aware about the short comings of this system and suggested us some possible modifications.
Further Mr. Srinivas G. provided us technical Know-how about Chain Hoisting Arrangement.
After lot many brain storming sessions by the team under the guidance of Mr. Pradeep Kumar, We propose a mechanical system ( Drawing Attached ) that will reduce human effort and is economical as well.
1.Members under load ( that are vulnerable to failure ) have been designed and dimensions are taken with factor of safety 2.
2. This system has been designed taking endurance limit ( 500 Million Cycles)
3. The system provides three degrees of freedom along three perpendicular axis.
4. Chain Hoisting Arrangement used is for 500 Kg Weight.
Objective – To design a mechanism for lifting and displacing pump and motor [ Total weight = 500 kg]
Functional characteristics of the system :- 1.Lifting capacity of 500 kgwt. 2. Movement along three perpendicular axis. i.e. 3 degrees of freedom. 3. Robust. 4. Economical 5. Endurance limit [ for 500 million cycles] Approach - Initial emphasis is an determination of sub-systems that could give three degrees of freedom Subsystem 1- Functions :- For forward and backward movement of the lifting system. Characteristics :- 1. Moderate sensitivity speed of movement should not be to high that is difficult to control. Proposed System :- We have chain and sprocket arrangement attached to a shaft and actuated manually by chain. Forced that can be applied by hand easily = 100 N Diameter of this sprocket wheel = 0.1 m Torque exerted by hand = 0.05 *100 = 5Nm This torque will rotate the shaft and the shaft is connected to pinion of comparitively smaller size. This torque will be transferred from pinion to larger gear. Since point of contact. Reaction force on both G1 and G2 is same. So,the torque transmitted will be T1/T2 = r1/ r2 T2= T1 * r2/r1 Torque can be increased in magnitude. This torque is driven gear rotates the roller attached by a shaft. Hence this wheel rotates and provides forward and backward movement. Design of transmitting shaft :- Torque to be transmitted = 0.5 Nm Shear stress = TC/J For shear stress Taking ASTM AJ6 (Tensile) Yield strength = 250 MPa (Shear) Yield strength = 125 MPa 125*10^6= 2.5 *d1/2/ π /32*d1^4 *d1^3 d1^3 = 2.5/ 125* 10^6 * π /32 =5.885*10^-3 m =5.885 mm. for safety , we take d1= 1.5cm
Design of pinion :- Since power to be transmitted is very low. so, we asumme pinion to be of diameter 3cm,
Design Of Pipe :-
Material : ASTM A36
Yield Strength : 250 MPa
Endurance limit = Ultimate Strength %2 > 250 MPa
Hence design is safe for 500 million cycles.
Bending stress in the pipe will be maximum when the weight is lifted from the farthest end that is for length = 2.70 m.
Maximum weight to be lifted = 750 Kg ( Including weight of railing ).
Therefore force = 7500 N
Bending Moment ( Max) = 7500 * 2.70 = 20250 Nm
Allowable bending stress in pipe = 125 MPa
Assuming Dimensions as :
External Dia = 330 mm
Internal Dia = 300 mm
Bending stress in pipe = M*Y%I =19 MPa
Tensile stress in pipe = .6 MPa.
Hence design is safe.
Design of I Section :-
Bending stress again will be maximum when the load is at the farthest end.
Material : ASTM A572.
Yield Stress : 300 MPa
For factor of safety = 1.5, Allowable stress = 200 MPa
Bending Moment( max) = 20250 Nm
Assuming dimensions as mentioned in drawing
Again calculating bending stress = 175 MPa.
Therefore design is safe.
Design Of Vertical shaft :-
Material : ASTM A36
Again Max Bending Moment = 20250 Nm
Let the dia of shaft be d mm.
Now , Bending stress (max) = 32 *20250*1000%(3.14*d ^3)
Now, allowable stress for shaft= 125 MPa
Calculating Dia , we get diameter of shaft = 12 cm.
We take the dia in drawing as 14 cm.
Design Of Shaft carrying weight :-
Length of shaft = 20cm
Again taking ASTM A36.
Maximum Bending Moment = 7500 * .1 = 750 Nm
Calculating Dia, we get diameter of shaft = 4.2 cm
Design Of Hub :
Outer Diameter of hub = 330 mm
Inner Diameter of hub is taken as per the external diameter of bearing.
Design Of Roller :
Since roller transfers weight to the railing , therefore it is in compression.
Taking allowable stress as 100 MPa,
Diameter * thickness = 7500%100
Therefore assuming suitable dimensions as Diameter of roller = 4cm and thickness as 1.5 cm
Design Of Gears :
Spur Gears have been used to transmit motion of chain to roller and they don’t have any load acting on them .
So, we need not design gears and select them depending upon availability in market.
Size of pinion and driven gear for this system has been mentioned in the drawing.
Design Of Mounting Plate:
Entire weight of system is transferred to ground through plate.
Allowable tensile Stress = 100 MPa
Since our plate is square in shape with side = 50 cm.
Tensile stress developed = .03 MPa.
Bending stress (max) =1.94 MPa.
We can use a smaller plate as well but the area of plate should be greater than that of pipe.
Tapered roller Bearing has been used for axial load of {7500 N ( tensile) and bending stress} . Radial load is quite smaller in magnitude as compared to axial load.
Bill Of Materials :-
S.No.
Name
1.
Supporting I-Section (Cantilever)
2.
Moving Part On Rail
3.
Supporting Members for Rollers
4.
Sprocket Wheel1
5.
Shaft
6.
Plate1
7.
Plate2
8.
Roller1
9.
Sprocket Support
10.
Bearing Support
11.
Roller2
12.
Driven Gear
13.
Pinion
14.
Sprocket Wheel2
15.
Transverse Member
16.
Bolts
17.
Driven Gear for forward and backward motion
18.
Wheel on Railing