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Steel Making

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

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

Pyrometry And Pyrometers
A knowledge of the fundamental principles of pyrometry, or th...

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Silicon prevents, to a large extent, defects such as gas bubb...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

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

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

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

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Impact Tests
Impact tests are of considerable importance as an indication ...

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

The Modern Hardening Room
A hardening room of today means a very different place from ...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

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

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

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

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.

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