25-09-2013, 02:45 PM
Rolling of metals
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Objectives
• This chapter provides information on different types of metal
rolling processes which can also be divided in to hot and cold
rolling process.
• Mathematical approaches are introduced for the
understanding of load calculation in rolling processes.
• Finally identification of defects occurring during and its
solutions are included.
Introduction- Definition of rolling process
• Definition of Rolling : The process
of plastically deforming metal by
passing it between rolls.
• Rolling is the most widely used
forming process, which provides high
production and close control of final
product.
Rolling process
• The metal is subjected to high
stresses as a result of
the friction between the rolls and the
metal surface.
Ring rolls
• Ring rolls are used for tube rolling,
ring rolling.
• Ring rolls are made of spheroidized
graphite bainitic and pearlitic matrix or
alloy cast steel base.
Typical arrangement of rollers for rolling mills
• Consist of a pair of heavy backing rolls
surrounded by a large number of planetary rolls.
• Each planetary roll gives an almost constant
reduction to the slab as it sweeps out a circular
path between the backing rolls and the slab.
• As each pair of planetary rolls ceases to have
contact with the work piece, another pair of rolls
makes contact and repeat that reduction.
• The overall reduction is the summation of a
series of small reductions by each pair of rolls.
Therefore, the planetary mill can hot reduces a
slab directly to strip in one pass through the mill.
• The operation requires feed rolls to introduce the
slab into the mill, and a pair of planishing rolls on
the exit to improve the surface finish.