Design of the machine components
Design of the shaft
The design of the shaft was carried out by considering the
properties of the material, loading on the shaft in terms of
weight of kolanut, and rubber paddles and making some basic
assumptions (Hall et al. 1983). The shaft length was 1600 mm.
The load on the shaft was partitioned as stated below:
Weight of kolanut to be processed at a time was specified
as 1 kg
Weight of kolanut ¼ 1 9:8 kgm=s2
¼ 9:81 N
Weight of flat bars and rubber paddles: this was determined
by weighing to be 50 g×16
0:8 kg 9:81 ¼ 7:848 N
Therefore equivalent load on shaft, Wt is given by
Wt ¼ weight of 16 paddles þ weight of kolanut ¼ ð9:81 þ 7:848Þ N
¼ 17:66 N
Bending and Torsional moments
Bending and torsional moment are the main factors influencing
shaft design. The point of critical stress was determined
from the bending moment diagram while the
torsional moment acting on the shaft was determined from:
Mt ¼ T1 T2 ð ÞR ð1Þ
Where,
T1 tight side of belt on pulley
T2 loose side of belt on pulley
R radius of pulley
Using the methods described by Hannah and Stephens
(2004), T1 and T2 were calculated as detailed below. The
required shaft diameter was determined by employing the
formula.
cos
θ
2
¼ r1 r2
l
ð2Þ
Where r10175 mm, r2030 mm and l0500 mm
cos θ2
¼ 0:1750:03
0:5
θ ¼ 2:553 rad
Hence angle of wrap of smaller pulley θ is 2.553 rad
V ¼ 1440 2
60
3:142 :03 ¼ 4:52 m=s
m ¼ ρ b t
Design of the machine components
Design of the shaft
The design of the shaft was carried out by considering the
properties of the material, loading on the shaft in terms of
weight of kolanut, and rubber paddles and making some basic
assumptions (Hall et al. 1983). The shaft length was 1600 mm.
The load on the shaft was partitioned as stated below:
Weight of kolanut to be processed at a time was specified
as 1 kg
Weight of kolanut ¼ 1 9:8 kgm=s2
¼ 9:81 N
Weight of flat bars and rubber paddles: this was determined
by weighing to be 50 g×16
0:8 kg 9:81 ¼ 7:848 N
Therefore equivalent load on shaft, Wt is given by
Wt ¼ weight of 16 paddles þ weight of kolanut ¼ ð9:81 þ 7:848Þ N
¼ 17:66 N
Bending and Torsional moments
Bending and torsional moment are the main factors influencing
shaft design. The point of critical stress was determined
from the bending moment diagram while the
torsional moment acting on the shaft was determined from:
Mt ¼ T1 T2 ð ÞR ð1Þ
Where,
T1 tight side of belt on pulley
T2 loose side of belt on pulley
R radius of pulley
Using the methods described by Hannah and Stephens
(2004), T1 and T2 were calculated as detailed below. The
required shaft diameter was determined by employing the
formula.
cos
θ
2
¼ r1 r2
l
ð2Þ
Where r10175 mm, r2030 mm and l0500 mm
cos θ2
¼ 0:1750:03
0:5
θ ¼ 2:553 rad
Hence angle of wrap of smaller pulley θ is 2.553 rad
V ¼ 1440 2
60
3:142 :03 ¼ 4:52 m=s
m ¼ ρ b t
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