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Steel Making

Bessemer Process
The bessemer process consists of charging molten pig iron int...

Sulphur is another impurity and high sulphur is even a greate...

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

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

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

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

MANGANESE is a metal much like iron. Its chemical symbol is M...

A combination of the characteristics of nickel and the charac...

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

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

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

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

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

Leeds And Northrup Optical Pyrometer


The principles of this very popular method of measuring temperature
are sketched in Fig. 123.

The instrument is light and portable, and can be sighted as easily
as an opera glass. The telescope, which is held in the hand, weighs
only 25 oz.; and the case containing the battery, rheostat and
milliammeter, which is slung from the shoulder, only 10 lb.

A large surface to sight at is not required. So long as the image
formed by the objective is broader than the lamp filament, the
temperature can be measured accurately.


Distance does not matter, as the brightness of the image formed
by the lens is practically constant, regardless of the distance
of the instrument from the hot object.

The manipulation is simple and rapid, consisting merely in the turning
of a knurled knob. The setting is made with great precision, due to
the rapid change in light intensity with change in temperature and
to the sensitiveness of the eye to differences of light intensity.
In the region of temperatures used for hardening steel, for example,
different observers using the instrument will agree within 3 deg.C.

Only brightness, not color, of light is matched, as light of only
one color reaches the eye. Color blindness, therefore, is no hindrance
to the use of this method. The use of the instrument is shown in
Fig. 127.

Next: Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer

Previous: Placing The Thermo-couples

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