Rivet is used to connect two or more plates inserted through the hole in plates and pressed on the other side.
The Unwin’s formula gives the diameter of the rivet hole for a given plate:
d = 6*t0.5
where, t = Thickness of plate in mm and
d = Diameter of the rivet in mm which is used to denote dimension of the rivet.
For steel plates, the rivets are made of low carbon steel. The rivets in copper add to resistance against corrosion and aluminum rivets can be used to lower the weight of the structure.
Rivets with countersunk head and oval countersunk rivets shown in bottom image are not as strong as button head rivets. Countersunk head and oval countersunk rivets are used only when protruding rivet heads are objectionable. Pan heads and conical heads are less frequently used and are difficult to produce. Tubular rivets have a special deviation from solid rivet shank. Tubular rivets are used in aircraft.
The classification of riveted joints can be done in following ways:
1. According to the purpose of rivets:
Based on purpose the riveted joints can be classified into three types:
1.1 Strong Joints: Strong rivet joints strength is the only criterion. These joints are used in engineering structure such as trusses, beams and machine frames.
1.2 Tight Joints: Tight rivet joints provide strength as well as are leak proof against low pressures. Joints in reservoirs, containers, and tanks fall under this group.
1.3 Strong Tight Joints: Strong tight rivet joints are used in boilers and pressure vessels and ensure both strength and leak proofless.
Classification of rivets based on purpose has no sound basis and is arbitrary. This classification of rivets helps to understand the basis of design and manufacturing.
2. According to the position of plates connected:
According to the position of plates connected riveted joints are classified into two types:
2.1 Lap joint: In a lap joint the edges of plates are simply laid over each other and riveted.
2.2 Butt joint: In Butt, joint plates lie in the same plane and joined through cover plates.
Reference: Riveted Joints PDF by IGNOU – The People’s University