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

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

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

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

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

Nickel-chromium
A combination of the characteristics of nickel and the charac...

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

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

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

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

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

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

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...



Hardening Operation






Category: HEAT TREATMENT OF STEEL

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.





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Previous: Temperature Recording And Regulation



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