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Introduction Of Carbon
The matter to which these notes are primarily directed is the...

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

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

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

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

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

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

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

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

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Critical Points
One of the most important means of investigating the properti...

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

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

Sulphur
SULPHUR is another element (symbol S) which is always found i...

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

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

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

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...



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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