Carburizing Low-carbon Sleeves
:
HEAT TREATMENT OF STEEL
:
The Working Of Steel
Low-carbon sleeves are carburized
and pushed on malleable-iron differential-case hubs. Formerly,
these sleeves were given two treatments after carburization in
order to refine the case and the core, and then sent to the grinding
department, where they were ground to a push fit for the hubs. After
this they were pushed on the hubs. By the method now employed,
the first treatment refines the core, and on the second treat
ent,
the sleeves are pushed on the hub and at the same time hardened.
This method cuts out the internal grinding time, pressing on hubs,
and haulage from one department to another. Also, less work is
lost through splitting of the sleeves.
The machine for pushing the sleeves on is shown in Fig. 64. At
A is the stem on which the hot sleeve B is to be pushed. The
carburized sleeves are heated in an automatic furnace, which takes
them cold at the back and feeds them through to the front, by which
time they are at the correct temperature. The loose mandrel C
is provided with a spigot on the lower end, which fits the hole
in the differential-case hub. The upper end is tapered as shown
and acts as a pilot for the ram D. The action of pushing on and
quenching is similar to the action of the Gleason tempering machine,
with the exception that water instead of oil is used as a quenching
medium. The speed of operation depends on a number of variables,
but from 350 to 500 can be heated and pressed on in 11 hr.