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Nickel
Nickel may be considered as the toughest among the non-rare a...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

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

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

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

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

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

Hardness Testing
The word hardness is used to express various properties of me...

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...



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.





Next: Carburizing Low-carbon Sleeves

Previous: Temperature Recording And Regulation



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