Technology Features of Apollo HDD Machine, Its Technical Specification with C...
Cotter joint
1. Subject :- Machine Design And Industrial Drafting
Topic :- Design of cotter joint
•Made By :-
-Utkarsh Gandhi -150990119007
-Digvijaysinh Gohil-150990119008
-Jaimin Prajapati-150990119010
-Abhijitsinh Kher-150990119012
•Guided By :-
-Mr. Rudra Parmar
2. COTTER JOINT
•A cotter joint is used to connect rigidly two co-axial rods or bars which
are subjected to axial tensile or compressive forces . It is a temporary
fastening.
• A cotter is a flat wedge shaped piece of rectangular cross section and its
width is tapered (either on one side or on both sides) from one end to
another for an easy adjustment.
.
Socket Cotter
Spigot
3. APPLICATIONS OF COTTER
1. Connection of the piston rod with the cross heads
2. Joining of tail rod with piston rod of a wet air
pump
3. Foundation bolt
4. Connecting two halves of fly wheel (cotter and
dowel arrangement)
4. Design of Spigot and Socket Cotter
Let P = Load carried by the rods,
d = Diameter of the rods,
d₁ = Outside diameter of socket,
d₂ = Diameter of spigot or inside
diameter of socket,
d₃ = Outside diameter of spigot
collar,
t₁ = Thickness of spigot collar,
d₄ = Diameter of socket collar,
c = Thickness of socket collar,
b = Mean width of cotter,
t = Thickness of cotter,
l = Length of cotter,
a = Distance from the end of the slot to the end of rod,
σt = Permissible tensile stress for the rods material,
τ = Permissible shear stress for the cotter material, and
σc = Permissible crushing stress for the cotter material.
5. SPIGOT BREAKING IN
TENSION OUTSIDE THE
JOINT
SPIGOT BREAKING IN
TENSION ACROSS
SLOT
Cotter joint – modes of failure
18. Example :- Design a socket and spigot joint to resist a
tensile load of 28kN. All the parts of the joints are
made from same material with following allowable
stresses:
σt=50 N/mm2 , σc=60 N/mm2 , τ=35 N/mm2 .
Solution,
Data :- P=28kN
σt=50 N/mm2
σc=60 N/mm2
τ=35 N/mm2
19. 1. Diameter of rod (d) :-
• Tensile stress induced in rod,
4/2
d
P
t
4/
10*28
50 2
3
d
mmd 30
20. 2. Diameter of spigot (dt) and thickness of cotter (t) :-
• Taking t=0.3d=0.3*30=9mm
• The tensile stress in spigot,
)9*4/( 1
2
dd
P
t
)9*4/(
10*28
50
1
2
3
dd
mmd 341
21. • The crushing stress in cotter and spigot:-
• Taking larger dia,
td
P
c
1
9*
10*28
50
1
3
d
mmd 521
mmd 521
22. 3.outside diameter of socket (Dt) :-
• The tensile stress in socket,
tdDdD
P
t
11
2
1
2
1 4/
9524/52
10*28
50
1
22
1
3
DD
mmD 601
23. 4.Distance from the end of slot to the end of spigot
(a):-
ad
P
12
a*52*2
10*28
35
3
mma 8
24. 5. Diameter of socket collar (D2) :-
tdD
P
c
)( 12
9)52(
10*28
60
2
3
D
mmD 602
25. 6. Thickness of socket collar (c) :-
• The direct stress in socket collar,
cdD
P
)(2 12
c)52104(2
10*28
35
3
mmc 8
26. 7. Diameter of spigot collar (d2) :-
• The crushing stress in spigot collar,
4/
2
1
2
2 dd
P
c
4/52
10*28
22
2
3
d
c
mmd 582
27. 8. Thickness of spigot collar (t1) :-
• The direct stress in spigot collar,
11td
P
1
3
*52*
10*28
35
t
mmt 51
28. 9. Width of the cottar (b) :-
• The direct shear stress in cottar,
bt
P
2
9*2
10*28
35
3
b
mmb 45
29. 10. Cottar under bending :-
• The maximum bending moment on cottar ,
42262
1112 dPddDP
M
462
112 ddDP
4
52
6
52104
2
10*28 3
mmN.10*033.3 3
30. • The maximum bending stress in a cottar,
3
12
1
2/*
tb
bM
I
MX
yy
b
2
6
tb
M
b
2
3
*9
10*033.3*6
50
b
mmb 64