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Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

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

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

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

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

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

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

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

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

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

Drop Forging Dies
The kind of steel used in the die of course influences the he...

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

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

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

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

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

Plant For Forging Rifle Barrels


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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