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

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

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

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

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

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

Quenching The Work
In some operations case-hardened work is quenched from the bo...

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

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

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

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

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

Quenching
It is considered good practice to quench alloy steels from th...

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

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

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



Plant For Forging Rifle Barrels






Category: THE FORGING OF STEEL

The forging of rifle barrels in large quantities and heat-treating
them to meet the specifications demanded by some of the foreign
governments led Wheelock, Lovejoy & Company to establish a complete
plant for this purpose in connection with their warehouse in Cambridge,
Mass. This plant, designed and constructed by their chief engineer,
K. A. Juthe, had many interesting features. Many features of this
plant can be modified for other classes of work.




The stock, which came in bars of mill length, was cut off so as to
make a barrel with the proper allowances for trimming (Fig. 21).
They then pass to the forging or upsetting press in the adjoining
room. This press, which is shown in more detail in Fig. 22, handled
the barrels from all the heating furnaces shown. The men changed
work at frequent intervals, to avoid excessive fatigue.



Then the barrels were reheated in the continuous furnace, shown
in Fig. 23, and straightened before being tested.

The barrels were next tested for straightness. After the heat-treating,
the ends are ground, a spot ground on the enlarged end and each
barrel tested on a Brinell machine. The pressure used is 3,000 kg.,
or 6,614 lb., on a 10-millimeter ball, which is standard. Hardness
of 240 was desired.

The heat-treating of the rifle blanks covered four separate operations:
(1) Heating and soaking the steel above the critical temperature
and quenching in oil to harden the steel through to the center;
(2) reheating for drawing of temper for the purpose of meeting the
physical specifications; (3) reheating to meet the machine ability
test for production purposes; and (4) reheating to straighten the
blanks while hot.

A short explanation of the necessity for the many heats may be
interesting. For the first heat, the blanks were slowly brought
to the required heat, which is about 150 deg.F. above the critical
temperature. They are then soaked at a high heat for about 1 hr.
before quenching. The purpose of this treatment is to eliminate
any rolling or heat stresses that might be in the bars from mill
operations; also to insure a thorough even heat through a cross-section
of the steel. This heat also causes blanks with seams or slight
flaws to open up in quenching, making detection of defective blanks
very easy.

The quenching oil was kept at a constant temperature of 100 deg.F.,
to avoid subjecting the steel to shocks, thereby causing surface
cracks. The drawing of temper was the most critical operation and
was kept within a 10 deg. fluctuation. The degree of heat necessary
depends entirely on the analysis of the steel, there being a certain
variation in the different heats of steel as received from the mill.





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