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Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

Tungsten, as an alloy in steel, has been known and used for a...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

Double Annealing
Water annealing consists in heating the piece, allowing it to...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

Hardening Operation


Hardening a gear is accomplished as follows:
The gear is taken from the furnace by the furnaceman and placed in
the lower die, surrounding the centering jaws, as shown at H in
Fig. 62 and C in Fig. 63. Air is then turned into the cylinder
D, and the piston rod E, the die carrier B, the top die F
and the expander G descend. The pilot H enters a hole in the
center of the lower die, and the expander G enters the centering
jaws I, causing them to expand and center the gear C in the
lower die. On further advance of the piston rod E, the expander
G is forced upward against the pressure of the springs J and
the upper die F comes in contact with the upper surface of the
gear. Further downward movement of the dies, which now clamp the
work securely, overcomes the resistance of the pressure weight
K (which normally keeps up the plunger A), and the gear is
submerged in the oil. The quenching oil is circulated through a
cooling system outside the building and enters the tempering machine
through the inlet pipe L. When the machine is in the position
shown, the oil passes out through the ports M in the lower plunger
to the outer reservoir N, passing to the cooling system by way of
the overflow O. When the lower plunger A is forced downward,
the ports M are automatically closed and the cool quenching oil
from the inlet pipe L, having no other means of escape, passes
through the holes in the lower die and the grooves in the upper,
circulating in contact with the surfaces of the gear and passes to
the overflow. When the air pressure is released, the counterweights
return the parts to the positions shown in Fig. 63, and the operator
removes the gear.

The gear comes out uniformly hard all over and of the same degree of
hardness as when tempered in an open tank. The output of the machine
depends on the amount of metal to be cooled, but will average from
8 to 16 per hour. Each machine is served by one man, two furnaces
being required to heat the work. A slight excess of oil is used
in the firing of the furnaces to give a reducing atmosphere and
to avoid scale.

Next: Carburizing Low-carbon Sleeves

Previous: Temperature Recording And Regulation

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