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Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

The Electric Process
The fourth method of manufacturing steel is by the electric f...

Gears
The material used for all gears on the Liberty engine was sel...

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

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

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

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

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

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

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

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

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

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

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

Annealing
There is no mystery or secret about the proper annealing of d...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

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

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



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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