Heating Of Manganese Steel
Another form of heat-treating furnace
is that which is used for the heating of manganese and other alloy
steels, which after having been brought to the proper heat are drawn
from the furnace into an immediate quenching tank. With manganese
steel in particular, the parts are so fragile and easily damaged
while hot that it is frequent practice to have a sloping platform
immediately in front of the furnace door down which the castings
may slide into a tank below the floor level. Such a furnace with
a quenching tank in front of its door is shown in Fig. 108.
These tanks are covered with plates while charging the furnace
and the cold castings are placed in a moderately cool furnace.
Since some of these steels must not be charged into a furnace where
the heat is extreme but should be brought up to their final heat
gradually, there is little discomfort during the charging process.
When quenching, however, from a temperature of 1,800 deg. to 1,900 deg.,
it is extremely unpleasant in front of the doors. The swinging
shield is here adapted to give protection for this work. As will
be noted it is hung a sufficient distance in front of the doors,
that it may not interfere with the castings as they come from the
furnace, and slide down into the tank.
To facilitate the work, and avoid the necessity of working with
the bars outside the edges of the shield, the slot-like hole is
cut in the center of the shield, and through this the bars or rakes
for dragging out the castings are easily inserted and manipulated.
The advantage of such a swinging shield is that it may be readily
moved from side to side, or forward and back as occasion requires.
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