[PSUBS-MAILIST] Re: Fabricating "T" bars

[Daniel Lance <lanceind@earthlink.net>]

Cliff,
There are two ways you can roll your flat bars to get the proper radius
along the whole bar.
One way is to cut the bar to the exact length and pre bend the end portion
that doesn't get formed by the roller ( a length equal to the center line
distance of your two bottom rolls).
The other way is to cut the bar over length by two times the center line
distance of the bottom rolls of your roller and then cut off the unrolled
portion after forming.
In Metal Fabricaters jargon your "T" bar will consist of two parts, one
rolled the easy way(the flange) and one rolled the hard way( the web).
Six inch rolls are what you need for rolling 1/4" thick SA516 GR70 (at least
the easy way)
When calculating bar lengths;
For outside diameter dimensions: subtract one plate thickness (or bar thk.)
from diameter before calculating circumference for proper length after
rolling.
For inside dimensions: add one plate thk. ( bar thk.) to diameter before
calculating circumference for proper length after rolling.
" The reason is as follows, the length of a piece of plate is only constant
for both sides as long as it is flat. When it is rolled, its length(or
circumference of the arc or circle it describes) becomes longer on the
outside and shorter on the inside. The only portion of the plate that
retains the original length is the middle of the plate thicknes, referred to
as the mean or neutral circumference". *
I hope this helps you,
Dan Lance


* The Metal Trades Handbook, IPT Industrial Publishing    Edmonton, Alberta
Canada  1985 



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