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

Critical Points
One of the most important means of investigating the properti...

Conclusions
Martien was probably never a serious contender for the honor ...

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

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

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

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

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

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

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

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

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

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

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

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...



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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