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UNIT 4 RIVETED JOINTS

Riveted Joints

Structure
4
...
2

Riveting

4
...
4

Nomenclature

4
...
6

Answers to SAQs

4
...

Whenever such joints are required to be permanent and capable of carrying high loads,
the engineers find choice between riveted and welded joints
...
Though
the riveted joints are no more favorite of engineers who have begun to prefer welded
structures for their strength, versalility and convenience of application, yet study of
riveted joints present classic advantage in drawing and mechanics
...


4
...
The rivets and sheets to be joined are
normally of the same material for economy and strength
...
1
...
The length of the cylindrical region
is equal to plate thicknesses through which the rivet passes
...

The plates are placed such that holes are coaxial, the rivet is inserted so that the tail part
protrudes out of the plate
...
If
cold, the tail is beaten through a die to shape into another head and if hot it is pressed
under the die to the head
...


75

Machine Drawings

Figure 4
...
2 along with the head formation by the die
...


Figure 4
...
3)
...
3

76

Rivets of several shaped heads are used mainly dictated by available space
...
Figure 4
...


Riveted Joints

Figure 4
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3 TYPES OF RIVETED JOINTS
The two types of riveted joints are apparent from application point of view
...
The standard plates, I-sections,
angle sections or channel sections or T-sections may be used in built up section
...
5 shows a large I-section built up from three plates (1), (2) and (3) and four
angles (4), (5), (6) and (7), such beams are called girders
...
5

The boiler joints, used in boilers and pressure vessel serve double purpose of providing
strength and stay leak proof
...

We have already seen a riveted joint in Figure 4
...
In this joint two plates to be joined are
placed over each other so that they partly overlap
...
In yet another type of plates are placed in the same planes so that their edges butt
each other
...
Instead of one cover there may be two-one top
77

Machine Drawings

and other below the butting edges
...
Figure 4
...
Figure 4
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(a) Single Riveted Lap Joint

(b) Double Riveted Lap Joint

Figure 4
...
6(a) and
Figure 4
...
Note that classifying a single riveted lap joint only one row of rivets passes
through two overlapping plate but for a single riveted butt joint one row of rivets passes
through each of the butting plate
...
7(b)
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(a) Single Riveted Butt Joint

(b) Double Riveted Butt Joint

(c) Chain Riveting

(d) Zig-Zag Riveting
Figure 4
...
In a lap joint
these forces do not act in a line but their lines of action are separated by a distance equal
to thickness of plate
...
In a butt joint the
tensile forces act in the same line if two covers are used
...


If in a double riveted joint in any one row there is a rivet corresponding to each in the
other row, the riveting is called chain
...
The joints in Figures 4
...
7(a) and (b) but the joint in Figures 4
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Riveted Joints

4
...
6 and 4
...

Pitch
Pitch, denoted by ‘p’, is the centre distance between adjacent holes in a row p = 3d
(minimum)
...
It is
denoted by pb , pb = 2d in chain or pb = 0
...
6 p in
zig zag riveting
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Margin
It is denoted by ‘m’ and represents the distance between a rivet hole centre and
nearest edge of the plate
...

The cover plate thickness is denoted by tc and tc = t/2 for double cover and tc = t for
single cover
...
Both d and D have been used to denote diameters of rivet and rivet
hole
...


SAQ 1
(a)

Figure 4
...
The plate
thickness is 12 mm, the rivet hole diameter is 21 mm and rivet diameter is
20 mm
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Figure 4
...
Find rivet
hole diameter, margin, pitch and back pitch
...
Draw the
front sectional view and plan
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9
...
Draw the front and
plan for three rivet length
...
9

(d)

Figure 4
...
Take the thickness of two cover plates as 0
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Draw two views of the joint if t = 16 mm
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10

(e)

80

Two steel plates 12
...

The steel plates are 320
...
11 with proposed holes
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Figure 4
...
12 are riveted as shown in
Figure 4
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5
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Riveted Joints

Figure 4
...
13

(g)

Two plates 22 mm thick are joined by double riveted butt joint with rivets of
27 mm diameter
...
2 mm
...
5 mm each
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4
...
Overwhelming
application of such joining in fabrication of bridge, ships and pressure vessel was due to
convenience and economy
...
The study of riveted joints by way of drawing helps understand
drawing of complicated objects
...
Drawing of these joints will be greatly useful
...
6 ANSWERS TO SAQs
SAQ 1
(a)

The sectional front view and full plan are shown in Figure 4
...

Take p = 3 D = 3 × 20 = 60 mm, m = 1
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5 × 20 = 30 mm
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14 : Two Views of a Single Riveted Lap Joint

(b)

Rivet hole diameter, d = 6 t = 6 16 = 24 mm
...
5 d = 1
...
8 p for chain riveting
pb = 0
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Figure 4
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15 in isometric view
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16
...
16 : Two Views of Chain Double Riveted Lap Joint

(c)

The Figure 4
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Riveted Joints

Diameter of rivet hole, D = 6 t = 6 12 = 20
...

The diameter of rivet may be taken as d = 20 mm
...
6p for zig-zag riveting
pb = 0
...
5d = 1
...
86 mm

The two views of the joint are drawn in Figure 4
...


Figure 4
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625 × 16 = 10 mm

Diameter of rivet hole,

d= 6

Diameter of rivet,

d1 = 23 mm

t = 6 16 = 24 mm

P = 3d = 3 × 24 = 72, m = 1
...
5 × 24 = 36 mm
The front view in section and full top view (plan) are shown in Figure 4
...


Figure 4
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19 is the indicative drawing of the butt joint known as
lozzenge joint due to its appearance
...


Figure 4
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13 shows the indicative drawing and based upon this draw the third
view from Figure 4
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Figure 4
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21
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Develop the elevation and section
along AA
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21

84



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