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Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

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

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

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

Chromium
Chromium when alloyed with steel, has the characteristic func...

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

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

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

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

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

Corrosion
This steel like any other steel when distorted by cold worki...

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

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

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

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

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

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



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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