Rivet

From Wikipedia, the free encyclopedia

For other uses, see Rivet (disambiguation).

A riveted buffer beam on a steam locomotive

A rivet is a permanent mechanical fastener. Before it is installed it consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is simply called the buck-tail. On installation the rivet is placed in a pre-drilled hole. Then it is "upset" (i.e. deformed) so the shaft fills the hole and the tail expands to about 1.5 times the original shaft diameter and holds the rivet in place. To distinguish between the two ends of the rivet, the original head is called the factory head and the deformed end is called the buck-tail.

There are several methods for upsetting the rivet. Rivets that are small enough and soft enough are often "bucked". In this process the installer places a rivet gun against the factory head and holds a bucking bar against the tail or a hard working surface. The bucking bar is a specially shaped solid block of metal. The rivet gun provides a series of high-impulse forces that upset the rivet in place. Rivets that are large or hard may be more easily installed by squeezing instead. In this process a tool in contact with each end of the rivet clinches to deform the rivet.

Because there is effectively a head on each end of an installed rivet it can support tension loads (loads parallel to the axis of the shaft); however, it is much more capable of supporting shear loads (loads perpendicular to the axis of the shaft). Bolts and screws are better suited for tension applications.

Three aluminium blind rivets: 1/8", 3/32", and 1/16". The shaft pulls out leaving only a rivet—everything below the flange.

Blind rivets are tubular and are supplied with a mandrel through the center. The rivet assembly is inserted into a hole drilled through the parts to be joined and a specially designed tool used to draw the mandrel into the rivet. This expands the blind end of the rivet and the mandrel snaps. This gives the rivets their common name of pop rivet (See blind rivet). Blind rivets are often avoided for critical structural joints because they generally have less load carrying capability than solid rivets. Furthermore, because of the mandrel they are more prone to failure from corrosion and vibration.

[edit] Types of rivets

There are a number of types of rivets: solid rivets, blind rivets, multi-grip rivets, grooved rivets, peel type blind rivets, self-pierce rivets, plastic rivets, drive rivets, tubular rivets, etc. Fastenings used in traditional wooden boat building like copper nails and clinch bolts work on the principle of the rivet but they were in use long before the term rivet was invented. So, where they are remembered, they are usually classified among the nails and bolts respectively.

Original rivet from the Forth Bridge.

Before welding techniques and bolted joints were developed, metal framed buildings and structures such as the Eiffel Tower and the Sydney Harbour Bridge were generally held together by riveting. Also automobile chassis were riveted. Riveting is still widely used in applications where light weight and high strength are critical, such as in an aircraft.

Common but more exotic uses of rivets are to reinforce jeans and to produce the distinctive sound of a sizzle cymbal.

The stress and shear in a rivet is analyzed like a bolted joint.