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The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Annealing Work
With the exception of several of the higher types of alloy s...

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

Hardening
Steel is hardened by quenching from above the upper critical....

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

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

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

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

Machineability
Reheating for machine ability was done at 100 deg. less than ...

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...

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

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

Phosphorus
PHOSPHORUS is an element (symbol P) which enters the metal fr...

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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