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Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

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

High Speed Steel
For centuries the secret art of making tool steel was handed ...

The Thermo-couple
With the application of the thermo-couple, the measurement of...

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

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

Air-hardening Steels
These steels are recommended for boring, turning and planing...

Manganese
Manganese adds considerably to the tensile strength of steel,...

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

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

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

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

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

Silicon
SILICON is a very widespread element (symbol Si), being an es...

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

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

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

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

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



Machineability






Category: ANNEALING

Reheating for machine ability was done at 100 deg. less than the drawing
temperature, but the time of soaking is more than double. After
both drawing and reheating, the blanks were buried in lime where
they remain, out of contact with the air, until their temperature
had dropped to that of the workroom.

For straightening, the barrels were heated to from 900 to 1,000 deg.F.
in an automatic furnace 25 ft. long, this operation taking about 2
hr. The purpose of hot straightening was to prevent any stresses
being put into the blanks, so that after rough-turning, drilling
or rifling operations they would not have a tendency to spring
back to shape as left by the quenching bath.

A method that produces an even better machining rifle blank, which
practically stays straight through the different machining operations,
was to rough-turn the blanks, then subject them to a heat of practically
1,0000 for 4 hr. Production throughout the different operations is
materially increased, with practically no straightening required
after drilling, reaming, finish-turning or rifling operations.



FIGS. 24 and 25.--Roof system of cooling quenching oil.]

This method was tested out by one of the largest manufacturers and
proved to be the best way to eliminate a very expensive finished
gun-barrel straightening process.



The heat-treating required a large amount of cooling oil, and the
problem of keeping this at the proper temperature required considerable
study. The result was the cooling plant on the roof, as shown in
Figs. 24, 25 and 26. The first two illustrations show the plant as
it appeared complete. Figure 26 shows how the oil was handled in
what is sometimes called the ebulator system. The oil was pumped
up from the cooling tanks through the pipe A to the tank B.
From here it ran down onto the breakers or separators C, which
break the oil up into fine particles that are caught by the fans
D. The spray is blown up into the cooling tower E, which contains
banks of cooling pipes, as can be seen, as well as baffies F. The
spray collects on the cool pipes and forms drops, which fall on
the curved plates G and run back to the oil-storage tank below
ground.

The water for this cooling was pumped from 10 artesian wells at the
rate of 60 gal. per minute and cooled 90 gal. of oil per minute,
lowering the temperature from 130 or 140 to 100 deg.F. The water as
it came from the wells averaged around 52 deg.F. The motor was of a
7-1/2-hp. variable-speed type with a range of from 700 to 1,200
r.p.m., which could be varied to suit the amount of oil to be cooled.
The plant handled 300 gal. of oil per minute.





Next: Annealing

Previous: Plant For Forging Rifle Barrels



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