Types of Rivets - ITI Engineering Drawing Theory
ITI Exam
1 Snap head rivet
(Fig 1) Draw a snap head rivet suitable for joining plates of 25 mm
thick.
Diameter of
rivet = 6 x 25 = 6 x 5 = 30 mm
• Draw a
thin horizontal line.
• Draw
vertical centre lines.
• Mark
diameter of rivet shank and head.
• Form the rivet head as per proportions.
• Draw the
shank with short break.
• Draw firm
lines of the edges of the rivet.
• Show the
dimensions in terms of dia of shank. (Fig 1)
2 Pan head rivet
Draw a pan head rivet of shank diameter 30 mm. (Fig 2)
• Follow the
procedure of snap head rivet.
3 Conical head rivet
Draw a
conical head rivet of shows diameter 25 mm. (Fig3)
• Draw a
horizontal thin line.
• Draw a
vertical centre line.
• Mark the diameter of rivet head and shank as
per proportion.
• Set off
0.8d on the centre line as shown in Fig 3 from the horizontal line.
• 0.25d as
radius, draw an arc as shown in Fig 3.
• 1.5d as
radius, draw another arc, tangential to the previous arc of radius 0.25d.
• Draw the
firm lines of the edges of the rivet.
• Show the
dimensions in terms of diameter of shank.
4 Countersunk head rivet
Draw a countersunk head rivet of shank
diameter 25 mm.
• Draw a
horizontal line.
• Draw a
centre line.
• Follow the
procedure of earlier exercises and complete the rivet head.
Types of rivets:
• Boiler
rivets
• Hot forged
rivets for hot closing
• Cold
forged solid steel rivets for hot closing
•
Non-ferrous rivets
• Cold
forged rivets for cold closing
•
Bi-furcated rivets for general purposes
• Solid
drilled tubular and semi-tubular rivets.
Rivets are
also broadly classified as:
• Structural
rivets
• Boiler
rivets
• Small
rivets for general work
• Rivets for
ship building
• Aircraft
rivets.
Rivets are
manufactured either by cold heading or hot forging. Cold headed rivets are
adequately heat-treated so that the stresses set up in the cold heading process
are eliminated. If they are hot forged, the finished rivets are cooled
gradually. The rivets should be concentric with the shank. They shall be free
from imperfection and heavy scales. The ends of the rivets shall be clearly
sheared and free from rags or burrs.
They are
available in different lengths and selected according to the requirements
(IS:1928 for boiler rivets, dia 12 to 48mm).
Boiler
rivets of different types of heads as per IS:1928-1961 are shown in Fig 2. They
are
• Snap head
•
Ellipsoidal head
• Pan head
type I & II
• Pan head
with taper neck
• Conical
head
•
Countersunk head
• Rounded
countersunk head
• Flat head
• Steeple
head
Boiler
rivets are used in boiler shells, mountings gussets stays etc. They have
generally tapered necks at 60° chamfer for preventing the leakages of steam.
Table 1 shows the preferred length and diameter combination for boiler rivets.
Structural/General purpose rivets IS:1929, IS:2155:
Structural rivets
are used in structures like girders of bridges, trusses of roof etc.
Their shank
dia (IS:1929) varies from 12 mm to 36 mm. The proportions shown are for rivets
of diameter from 12 mm to 36 mm. The above rivets are used even for general work.
The dimensions
are from 12 mm to 50 mm. Structural rivet and boiler rivets are made of low
carbon steel and wrought iron. (Fig 3)
Small rivets
are used for general work, may be made of "non-ferrous metals" viz
copper, brass or aluminium. Diameters are 1.6, 2, 2.5, 3, 4, 5, 6, 8 and 10 mm
of varying lengths in steps of 2 mm upto 24 mm and then in steps of 3 mm.
IS:2907.
Rivets are
designated by its shape, dia, length, IS. No and materials.
ITI ED Exam - ITI Engineering Drawing
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