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The process of reducing the thickness or changing the cross section of a long workpiece by compressive forces applied through a set of rolls.
Generally have a thickness of more thatn 6 mm and are used for structural applications.
Generally less than 6 mm thick and typically are provided to manufacturing facilities as coils - weighing as much as 30,000 kg or as flat ones for further processing into various products.
A metal strip of thickness ho enters the roll gap and is reduced to thickness hf by a pair of rotating rolls, each powered individually by electric motors. The metal accelerates in the roll gap in the same manner as an incompressible fluid flowing through a converging channel.
The difference between the initial and final strip thicknesses in the flat-rolling process
When rolling is carried out only by front tension (though it has limited and specialized applications)
A rolled strip that is thicker at its center than at its edges
Grind the rols in such a way that their diameter at the ccenter is slightly larger than at the edges
When a roll becomes slightly barrel shaped due to heat generated by plastic deformation
Results from interactions between the structural dynamics of the mill stand and the dynamics of the rolling operation. Rolling speed and lubrication are found to be the two most important parameters.
The product of the first hot-rolling operation is called....
- a bloom (square cross section later structural shapes)
- a slab (plates or sheets)
- a billet (square but later made bars and rods)
A flat-rolling operation in which two or more layers of metal are rolled together, thus improving productivity.
To improve flatness, the rolled strip typically goes through a series of....
Used for hot rolling in initial breakdown passes
Two-high rolling mills
In this process, the direction of material movement is reversed after each pass, using elevator mechanism and various manipulators. The plate being rolled is repeatedly raised to the upper roll gap, rolled, then lowered to the lower roll gap, rolled, and so on.
Based on the principle that small-diameter rolls lower roll forces and power requirements and reduce spreading.
Strip is rolled continuously through a number of stands to thinner gages with each pass
Straight and long structural shapes (I-beams, rails, etc) are formed at elevated temperatures by this rolling process.
In this operation, the cross section of a round bar is shaped by passing it through a pair of rolls with profiled grooves.
A process that is typically used for making ball bearings, where roung wire or rod is fed into tthe roll gap and roughly spherical blanks are formed continuously by the action of the rotating rolls.
A thick ring is expanded into a large-diameter thinner one. The ring is placed between two rolls, one of which is driven while the other is idle. Its thickness is reduced by bringing the rolls closer together as they rotate.
A cold-forming process by which straight or tapered threads are formed on round rods or wire. The threads are formed on the rod or wire with each stroke of a pair of flat reciprocating dies.
Hot-working operation for making long, thick-walled seamless pipe and tubing. It is subjected continuously to cyclic compressive stresses and the bar begins to develop a small cavity at its center which then begins to grow.
Rotary Tube Piercing
The diameter and thickness of pipes and tubing are reduced by this method.
large facilities that involve complete integration of the activities - from the production of hot metal in the blast furnace to the casting and rolling of finished products ready to be shipped to the customer.
Facilities that utilize scrap metal that is melted in electric-rc furnaces, cast, and continuously rolled into specific lines of products.
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