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Steel Making

The crankshaft was the most highly stressed part of the entir...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

The Thermo-couple
With the application of the thermo-couple, the measurement of...

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

Molybdenum steels have been made commercially for twenty-five...

Steel is hardened by quenching from above the upper critical....

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Piston Pin
The piston pin on an aviation engine must possess maximum res...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

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

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

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

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

Manganese adds considerably to the tensile strength of steel,...

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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