Aircraft Rivets |
Ice Box Rivets | Aircraft Rivets brief description
Aircraft Rivets
The structure of
an aircraft are constructed by joining metal sheets together, and this is often
done with solid shank Aluminum-alloy rivets. When a rivet is made, it resembles a
metal pin with a formed head on one end. A hand or pneumatic tool upsets
(deforms) the rivet's shank after it has been inserted into a drilled hole. The
second head, which can be produced manually or with pneumatic tools, is
referred to as a "shop head."
Like a nut on a
bolt, the shop head serves the same purpose. Rivets are used to join spar
sections, hold rib sections in place, secure fittings to various parts of the
aircraft, and fasten countless bracing members and other parts together in
addition to joining aircraft skin sections. A bond formed by the rivet is at
least as durable as the materials being joined.
The common solid
shank type, which requires the use of a bucking bar, and the special (blind)
rivets, which can be installed in situations where a bucking bar cannot be
used, are two of the main types of rivets used in aircraft.
Hardware store
rivets are not used in aircraft. Hardware store rivets should never be used in
place of rivets of aeronautical quality. The materials used to make the rivets
might vary substantially, as can the strength and shear strength
characteristics of the rivets. Hardware store countersunk rivets feature 78°
angle heads, whereas aircraft countersunk rivets have 100° angle heads for
greater surface contact to hold it in place.
Compared to
rivets made for ordinary use, aircraft rivets are produced to significantly
higher standards and requirements. Different manufacturers had various rivet
head designs when aeroplane manufacturers began producing all-metal aircraft in
the 1930s. There were 78° countersunk heads, button heads, mushroom heads,
modified brazier heads, and brazier heads. Four rivet head designs largely
replaced all the others as aircraft standardized. The most common types of
rivets used for airflow exposure are universal head MS20470 or 100° countersunk
head MS20426 rivets. The flathead MS20442 and roundhead MS20430 are typically
used for rivets in internal structures.
Ice Box Rivets
A solid shank
aircraft rivet made of 2017-T or 2024-TAluminium-alloy are known as Ice box rivets, are annealed and must be kept refrigerated until they are
to be driven. These rivets are too hard to drive in the condition they are
received from the manufacturer without heat treatment. On receipt from the
manufacturer, these rivets are heat treated to make it soft and, thereafter,
quenched in water. These rivets are then kept in a refrigerator/ icebox until
they are ready to be used.
In Aluminuim-alloy structures when higher strength is required than can be achieved
with the same size 2217-T rivet, the 2017-T and 2024-T rivets are employed.
After being removed from refrigeration, the 2017-T rivet should be driven in
about an hour and the 2024-T rivet in about ten to twenty minutes.
Particularly
with aluminum-alloy rivets, metal temper plays a significant role in the
riveting process. The heat-treating properties of aluminum-alloy stock and
rivets are identical. They can undergo the similar annealing and hardening
processes as aluminum. Before a nice head may form, the rivet must be soft or
rather soft. Prior to driving, the 2017-T and 2024-T rivets are annealed. Age
makes them harder.
Similar to heat
treating (annealing) stock, rivets are treated in a similar manner. It is
necessary to use an electric air furnace, a salt bath, or a hot oil bath.
Depending on the alloy, the heat-treating temperature ranges from 625 °F to 950
°F. Rivets are heated in a wire basket or tray for easy handling. After being
heat treated, they are promptly quenched in cold water (70 °F).
The
heat-treatable 2017-T and 2024-T rivets start to age harden within a few
minutes of exposure to ambient temperature. They must therefore be put in cold
storage if not used right once after quenching.
Refrigeration is
the most popular method for preserving heat-treatable rivets at low
temperatures (below 32 °F). "Icebox" rivets are the name given to
them. They can be kept in this storage situation for up to two weeks and still
be soft enough to drive on. Any rivets that aren't used within that time frame
need to be taken out for reheat treating.
After driving,
icebox rivets reach roughly half of their maximum strength in about an hour,
and their full strength in about four days. 2017-T rivets must need reheat
treatment if they are left at room temperature for more than an hour. This also
holds true for 2024-T rivets that have spent longer than 10 minutes at room
temperature.
An icebox rivet
should never be mixed with rivets that are still in cold storage after it has
been removed from the refrigerator. If you take out more rivets from the fridge
than you can use in 15 minutes, store the extra ones for reheating in a
different container. If done correctly, heat treating rivets can be done
repeatedly.
Types of aircraft rivets
The three types of rivets that are most frequently used are mechanically expanded, blind, and solid shank rivets. Nonstructural type self-plugging (friction lock) rivets and pull-through rivets, also known as mechanical lock—flush fracturing, self-plugging rivets, are two classes of mechanically expanding rivets.
Solid shank rivets
Generally, solid shank rivets are used for repairs. Their type of head, size of shank, temper state, and type of material from which they are produced are all used to identify them. The cross-sectional shape of the head determines the name of the solid shank rivet head type, such as universal head, roundhead, flathead, countersunk head, and brazier head. Special marks on the rivet head identify the temper designation and strength. The majority of aviation solid shank rivets are made of aluminum-alloy.
For
riveting buildings made of aluminium-alloy, the 2117-T rivet, also referred to
as the field rivet, is most frequently employed. The field rivet is highly
sought after since it can be used right away and doesn't require any additional
heat treating or annealing. It also has a high level of corrosion resistance
properties.
Blind Rivets
There
are numerous locations on an aeroplane where it is hard to access both sides of
a riveted structure or structural component or where there is not enough room
to employ a bucking bar. Furthermore, the entire strength of solid shank rivets
is not required for the connection of various nonstructural components, such as
flooring, deicing boots, and other interior furnishings for aircraft.
Special
rivets that can be bucked from the front have been created for use in such locations.
Special rivets can be lighter than solid shank rivets while yet being extremely
strong for the intended application. These rivets are made by a variety of
manufacturers and have distinctive qualities that call for special removal
tools, special removal techniques, special installation techniques, and special
removal techniques. They are known as unique rivets for this reason. These
rivets are also known as blind rivets because they are frequently placed in
areas where one head (typically the shop head) cannot be seen.
Self-Plugging Rivets (Friction Lock)
The
friction lock self-plugging blind rivets are produced by a variety of
companies. All of them share the same fundamental information regarding their
production, composition, uses, selection, installation, inspection, and removal
processes.
A
rivet head with a hollow shank or sleeve and a stem that extends through the
hollow shank are the two components that make up self-plugging (friction lock)
rivets.
When
a pulling force is applied to the stem of the rivet, several things happen in
the right order:
- The stem of these rivet is pulled into the rivet hollow shank.
- The mandrel portion of the stem forces the rivet shank to expand into the hole.
- When friction (or pulling force) becomes great enough, it causes the stem to snap at a breakoff groove on the stem.
Since
the plug section (bottom end of the stem) is kept in the rivet's shank, it has
a far higher shear strength than a hollow rivet would
The
two most popular head designs for self-plugging (friction lock) rivets are a
protruding head like the MS20470 or universal head and a 100° countersunk head.
From some manufacturers, you can choose from several head shapes.
The
upper portion of the stem of the self-plugging (friction lock) rivet may be a
knot, knob, or it may be serrated.
Rivets
that self-plugging (or friction lock) are made of various materials. In addition
to stem 2017 Aluminum-alloy and sleeve 2117T Aluminium-alloy, stem 2017 Aluminium-alloy and sleeve 5056 Aluminum-alloy, and stem steel and sleeve
steel, rivets are also available in the following material combinations.
Self-plugging
(friction lock) rivets are created so that only one person is needed for
installation; access from both sides is not required. Because of the rivet
stem's superior pulling power, a consistent work can always be guaranteed.
Self-plugging (friction lock) rivets can be used to attach assemblies to hollow
tubes, corrugated sheet, hollow boxes, and other materials because access to
the opposite side of the work is not required. The rivet can be used to fasten
assemblies to plastic or plywood because hammering is not required for its
installation.
Pull-Thru Rivets
The
pull-thru blind rivets are made by a number of businesses. All of them share
the same fundamental information regarding their production, composition, uses,
selection, installation, inspection, and removal processes. Two components make
up pull-thru rivets: a rivet head with a hollow shank or sleeve and a stem that
extends through the hollow shank.
When
a pulling force is applied to the stem of the rivet, several things happen in
the right order:
- The stem of these rivet is pulled through the rivet hollow shank.
- The mandrel portion of the stem forces the shank to expand forming the blind head and tightly filling the hole.
Two
common head designs are produced for pull-thru rivets: a 100° countersunk head
and a projecting head like the MS20470 or universal head. From some
manufacturers, you can choose from several head shapes.
There
are various materials used to make pull-thru rivets. The most widely utilized materials are Monel, 5056 aluminum-alloy, and 2117-T4 aluminum-alloy.
Pull-thru rivets are made to be installed by just one person; access from both
sides of the work is not required.
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