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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

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

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

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

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

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

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

Connecting Rods
The material used for all connecting rods on the Liberty engi...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

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

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

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Nickel-chromium
A combination of the characteristics of nickel and the charac...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...



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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