Swaging-> Thread Rolling (E) Flashcards
SWAGING
Uses multiple dies that close on the part along radial paths. can be done with large machines or HAND TOOLS
HYDRAULIC SWAGING TOOLS
Use a pumping action for deforming ferrous metals
HAND SWAGING TOOLS
Oversized pair of pliers that uses a compound lever action to generate large forces between the jaws (dies)
FERRULE
A metal ring or cap that strengthens the end of a cable and prevents it from splitting or wearing.
INDUSTRIAL SCALE SWAGING
uses multiple dies that all move towards the center simultaneously
Why is SWAGING used to produce RATCHET SOCKET WRENCH SETS?
superior strength is required but minimal metal is available to resist the loads
SOCKETS of a RATCHET SOCKET WRENCH
hollow but suddenly transition from a hexagonal hole (to slip over the nut/bolt) to a square hole (to attach to the ratchet drive lug)
Why should the SOCKET holes never be cut?
Cutting them would sever the grain flow and compromise strength
How are holes created in SWAGING?
MANDRELS
MANDREL
a metal tool around which other metal is formed, mirrors the internal cavity of the part
What must happen to the metal used for SWAGING?
first, it must be OPEN DIE FORGED to create a WROUGHT structure. then it is formed into a tubular shape with internal and external dimensions slightly larger than the final product.
ROTARY SWAGING
the process that allows long lengths of material to be SWAGED. A ring of cam followers is rotated while being driven inwards and outward.
How are “cold hammer forged barrels” for long guns made?
ROTARY SWAGING
How is a Philips head screwdriver made?
SWAGING, doesn’t need a MANDREL because it is solid, not hollow
ROLL-FORGING
A manufacturing process in between rolling and forging. Discrete products can be created between rotating dies (rollers) with an evolving shape attached around their perimeter.
SKEW ROLLING
An example of ROLL-FORGING used to make steel balls for use in bearings. Two conical rollers with helical grooves of semicircular cross-section are offset at an angle (skewed).
ROLLING
A process that produces very long lengths of stock material using dies in the form of ROLLERS.
CONTINUOUS CASTING
molten metal is formed into SLABS which then enters into the ROLLER stages which is a non-stop process
PLATE/SHEET STOCK
material rolled using smooth and featureless rollers
ROLLERS
crush the CAST STRUCTURE and turn it into a WROUGHT STRUCTURE, reduce thickness.
HOT ROLLING
ROLLING done at temperatures above recrystallization to avoid microcracking.
ADVANTAGE of ROLLING
it provides stock with forged-like strength, inexpensive, long pieces of stock
ROLLING MILLS
facilities where ROLLING is performed. these buildings can be up to 1/4 miles long.
Stages of ROLLING PROCESS
reheat furnace
roughing mill
coil box
tensioning
finishing mill
cooled and coiled
HOT ROLLED PLATE or SHEET
the final result of rolling processing
What is the difference between PLATE and SHEET material?
PLATE material must be stacked flat
SHEET material can be coiled
MILL SCALE/BLACK IRON OXIDE
black/gray coloration that forms on the surface at elevated temperatures. it can be cleaned off during the ROLLING process, but it will reform if hot enough. it is somewhat protective of the underlying metal and will hinder corrosion.
What are the additional processing steps that turn HOT ROLLED STEEL into COLD ROLLED STEEL
ANNEALING & PICKLING, TEMPER ROLLING
ANNEALING
softening heat treatment of the hot rolled steel
PICKLING
mill scale is removed
TEMPER ROLLERS
reduce the thickness by a few thousandths of an inch at room temperature.
advantage and disadvantage of COLD ROLLED STEEL
it is more refined, but more expensive
SHAPE or PROFILE ROLLING
uses grooves rollers to create STRUCTURAL STOCK from cast “bloom”, but can include a variety of additional rollers of various sizes, shapes, and orientations to form the required cross-sections.
ROLLING DEFECTS
wavy edges
zipper cracks in the center of the flat rolling
edge cracks
alligatoring
How are ROLLING DEFECTS generally caused?
heating issues, too aggressive thickness reduction steps, or deficient rigidity/concentricity of the roller systems
ALLIGATORING
ROLLING DEFECT where the end of the rolled product resembles the open jaws of an alligator. It is caused by the upper and lower surfaces of the material getting attached to the rollers.
How do rolling mills avoid alligatoring?
it is standard practice to saw a foot or so off the ends of rolled product to remove the possibility of hidden alligator cracks.
RING ROLLING
used to create large circular workpieces using rollers
SPLINE ROLLING
done with linear style dies or with more traditional rollers similar to those in ROLL-FORGING.
SPLINES
grooves used to concentrically attach shafts together for torque transmission, and require proper grain flow for strength
BOLTS
critical for assembling structures and must be strong.
HEADING or ORBITAL FORGING
used to create the heads of BOLTS and ensure proper grain flow.
THREAD ROLLING
ROLLERS with helical grooving or LINEAR DIES with angled grooves create the threads of a bolt to be strong
CUTTING THREADS
will always produce weak, smooth, sharp, precise threads, and will result in a major diameter EQUAL to the shank.
ROLLED THREADS
very strong, more rounded, and result in a major diameter that is LARGER than the shank.
PRECISION BOLTS
“best of both worlds” between ROLLED and CUT THREADS
