Embed Size (px)
Citation preview
Riveted jointsWelded jointsPin joints
Siddharth Kotecha div :T roll no. 3 Akshay Phadtare div :T roll no. 27
rivets
Solid rivetsSemi tubular rivetsBlind rivetsDrive rivetsFlush rivetsFriction-lock rivets
Solid rivets consist simply of a shaft and head which are deformed with a hammer or rivet gun.
Solid rivets are driven using a hydraulically, pneumatically, or electromagnetically driven squeezing tool or even a handheld hammer.
Similar to solid rivets, except they have a partial hole (opposite the head) at the tip.
The force needed to apply a semitubular rivet is about 1/4 of the amount needed to apply a solid rivet.
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.
blind rivets are mainly used when access to the joint is only available from one side.
A drive rivet is a form of blind rivet that has a short mandrel protruding from the head that is driven in with a hammer to flare out the end inserted in the hole.
A flush rivet is used primarily on external metal surfaces where good appearance and the elimination of unnecessary aerodynamic drag are important.
pto
Cherry friction-locks were available in two styles, hollow shank pull-through and self-plugging types. The pull-through type is no longer common, however, the self -plugging Cherry friction-lock rivet is still used for repairing light aircraft.
Cold Rivets -permanently join plates together.
Steel rivets used for joining steel plates while aluminium rivets used for aluminium plates.
Rivets available made from materials such as copper and brass.
The material of the rivet normally matches the material to be riveted together.
Generally rivets made from aluminium, steel, copper or brass
Head of the rivet is set to rest in the 'dome' of a ‘dolly’. A typical 'dolly' is shown on the left. This tool is held in an engineers vice and it supports the rivet’s head.
The plates are placed over the rivet, resting on the top surface of the dolly.
4.
The plates pushed over rivet and in order to ensure there are no gaps between them a rivet set is pushed pushed down, over the rivet's shaft.
The rivet's shaft fits inside a small hole at the base of the rivet set.
This closes any gap between the two plates.
.
A ball pen hammer is used to tap the plates together.
If this is not done, the plates may be move slightly, even after a series of rivets have been hammered in position
The ball pein hammer is reversed and used to expand the ‘tail’ of the rivet.
This may take several slight taps. At this point the rivet cannot be removed from the plates.
The ball pein side of the hammer is used to form the rivet head.
The head should form a dome.
The final shaping of the rivet head is formed using the rivet snap.
The plate should be permanently fixed together at this stage.
Over 3Million rivets were used in the construction of
The Titanic
SNAP RIVETS
Snap rivet joint in folded metal
Riveted levis jeans pocket which we use daily…This riveted pocket is patented by levis strauss
Butt JointCorner JointT-JointLap JointEdge Joint
Butt joint- a joint between two members aligned approximately in the same plane
Corner joint - a joint between two members located at right angles to each other
T-JointT- joint - a joint between two members located approximately at right angles to each other in the form of a T
Lap Joint
Lap Joint- a joint between two overlapping members
Edge Joint
Edge joint- a joint between the edges of two or more parallel or nearly parallel members
(a) round pins
(b) Taper pins
(c) Dowel pins (d) Split pins
Round and taper pins are simple cylindrical pins with or without a taper and they
offer effective means of fastening pulleys, gears or levers to a shaft. It may be
fitted such that half the pin lies in the hub and the other half in the shaft.
These joints give positive grip and the pins are subjected to a shear load. For example, for the shaft in the assembly
These are used to
keep two machine parts in proper alignment.
figure demonstrates the use of dowel pins. Small cylindrical pins are normally used for this purpose.
These are sometimes called cotter pins also and they are made of annealed iron
or brass wire. They are generally of semi-circular cross section and are used to
prevent nuts from loosening . These are extensively
used in automobile industry.
Large: structural work of buildings and bridges Aerospace equipment Small Blind: blind riveting is a technique for setting a
rivet without access to the reverse side of the joint
LARGE RIVETS
MISCELLANEOUS FASTENERS
RIVETEDJOINTS
MISCELLANEOUS FASTENERS
MISCELLANEOUS FASTENERS
RIVETEDJOINTS
CONVENTIONAL RIVET SYMBOLS
MISCELLANEOUS FASTENERS
1 2 3 4
Hand Vice
Machine Vice
Twist Drill
Pillar Drill Ball Pein Hammer
Snap and Set
1. Snap head
2. Countersunk
3. Pan head
4. Flat head
STEP 1
Cut rivet to appropriate length. Length protruding through metal
should be equal to the diameter of the hole.
STEP 2
Put the set and snap in the vice and place the
rivet in position.
STEP 3
Use the set and snap to ensure there is no space between the metal or the rivet. This is
known as “setting” the material.
STEP 4
Using the ball pein hammer swell the tail of the rivet so that the material is locked in
position before you start to “dome” the head.
STEP 5
Using the ball end of the ball pein hammer dome the swolen tail of the rivet into a rough
snap head shape.
To finish off use the “snap” on the set and snap tool to produce a neat snap head.
Cut rivet to correct length
Bring pieces of metal together with rivet set
Swell the rivet with the flat face of the hammer
Form rivet with ball pein hammer
Finish forming head with snap
Example of Pop Riveted Work
Pop Rivets Pop Rivet Gun
Pop rivet loaded in gun and fed through material.
The pin is removed and the pop rivet leaves a permanent joint between the metal.
As handle is squeezed, the pop rivet pin is pulled into the gun and lower piece is deformed.
Example of Brazed Joint
Safety Glasses
SafetyGloves
Gas Torch
Brazing Hearth
(Part of the Forge)
Brazing Rod/ Spelter
(copper-zinc alloy)
Flux
STEP 1
Thoroughly clean/degrease the area to be joined (typically using steel wool or emery cloth) to ensure no grease or
rust will interfere with the joining process.
Once cleaned, apply flux. Flux prevents oxidation taking place on the metal
surfaces – which would prevent brazing being successful.
STEP 2
Focus of the torch on the area to joined, slowly moving the
torch backwards and forwards so that the area is evenly
heated to a bright red colour.
STEP 3
A brazing rod (copper-zinc alloy) is then pushed gently against the joint and if the temperature is
right the end of the rod will melt and begin to run along the joint. The rod is fed into the joint
until a brazed joint is complete.
It should be noted that the steel is allowed to cool slowly. If cooled quickly, such as quenching in water, the joint can crack or
become distorted.
KEY:
1) Direction of travel
2) Contact tube
3) Electrode
4) Shielding gas
5) Molten weld metal
6) Solidified weld metal
7) Workpiece.
Spot welding is a type of welding used to weld various sheet metals. Typically the sheets are in the 0.5-3.0 mm thickness range.
The process uses two shaped copper alloy electrodes to concentrate welding current and force between the materials to be welded.
The result is a small "spot" that is quickly heated to the melting point, this forms a nugget of welded metal after the current is removed.
Applying the current for too long can result in molten metal being expelled as weld splash, or can even burn a hole right through the materials being welded.
Adjust with use of spanners.Countersunk head can be flush with surface if hole is also countersunk.
Wing nut can be adjusted by hand, without tools.
Plain washed used to spread load from nut/protect surfaces from being tarnished when nut tightened against it – e.g. wood, painted surfaces, plastics.
Spring washers commonly used to lock nuts in place, especially when parts are vibrating such as an engine.
