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Steel Making

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

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

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

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

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

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

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

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

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

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

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

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

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

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

SULPHUR is another element (symbol S) which is always found i...

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

It is considered good practice to quench alloy steels from th...

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

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

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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