Improvements in Screw Propellers.
Year: 1895

page_text: Date of Application, 16th Feb., 1895
Complete: Specification: Left, 30th Sept., 1895-Accepted, 23rd Nov., 1895
PROVISIONAL SPECIFICATION..
Improvements in Screw Propellers.
I, JOHN GARDINER PENN, of the Exchange, Bute Docks, Cardiff, in the
County of Glamorgan, Engineer, do hereby declare the nature of my invention to
be as follows:
..
F
1.
This invention relates to the manufacture of screw propellers and propeller
blades for steam- and other vessels, and to forming the blade of the particular
quality of cast iron necessary for the purpose of being afterwards annealed by
any of the well-known processes for effecting that purpose, the resultant blade,
thereby becoming the materiál known as malleable cast iron.
.Y
I do not confine myself to the making of separate blades only but the whole
propeller may be made of the material-known as malleable cast iron and treated in
the same way as above specified for the manufacture of propeller blades only.
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My object in making propellers of this material is for the purpose of not only.
reducing theweight of the propeller and increasing its strength, but to make a
propeller that shall perform its functions without undue displacement and..cut
through the water without churning and absorbing, a large amount of motive
power, as is the case with all thick and heavy bladed propellers. When the
propeller is made with an ordinary cast iron boss, my improved malleable iron
blades will be as thin as bronze blades, at a very much less cost and with the-same
advantages, being of equal, if not of greater strength.
The blades may be made interchangeable and be fixed in any convenient manner
as may be found most desirable. To facilitate the annealing of the large flange
necessary for securing the blade to the boss, the metal may be cored out and made
very much thinner, than is possible with a cast iron or steel blade.
My invention includes annealing cast iron by any known method for the purpose
of making propellere, in the whole or part.
Dafad this 16th day of Rohro
Improvements in Screw Propellers.
I, JOHN GARDINER PENN of the Exchange, Bute Docks, Cardiff, in the
County of Glamorgan, Engineer, do hereby declare the nature of my invention
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
My invention relates to improvements in screw propellers and consists in an
improved process for the manufacture, and in the result of such improved
process an improved screw propeller.
The invention is equally applicable to screw propellers and to the blades of
screw propellers, in respect of the process of manufacture and of the articles
themselves.

page_text: In carrying the invention into effect, I prepare a mould or moulds and core
boxes for the propeller blades or the screw propeller, as the case may be,
because the first step in the improved process above mentioned is one of founding.
But special attention is required by my invention to be given to the thickness
of the patterns, to reduce the weight without lessening the strength, because,
according to the present invention, the iron casting. is converted into- malleable
cast iron by being heated to redness in a bed of red hematite ore, black oxide
of iron, or other material that will effect the same purpose: Now an iron casting
of a given transverse section is endowed with a definite strength in virtue of such
section, but after that casting has been converted from cast iron into malleable cast
iron, it finds itself endowed with a considerably increased strength. Consequently,
the patterns for the casting must be dimensioned to allow not only for the well
known: shrinkage of the cast iron in the mould but also add herein the novelty of
the present invention makes itself felt as a factor in the whole process for the
increment in strength due to the conversion......
The shrinkage of cast iron. in, the mould is on the average slightly-under an
eighth of an inch to the foot.
"'
The allowance to be made for the increment in strength cannot be stated pres
cisely because it varies with the quality of the metals and also with-tho-bcctional
area of the casting..
4.7.
=
The second step in the improved process is the conversion.
:
a 1.
This is effected in the usual and well known way, as far as regards the conversion
of the mass of the metal, but special-care must be taken that the skin is rendered
impervious to the action of the sea water by a due and regular oxidation
1
Having now particularly described and ascertained, the nature of my said
invention add in what, mander it is to be performed, I declare that what
Iclaim is
" .j
FLY.
The herein before described improved process for the manufacture of propeller
blades and screw propellers, consisting in casting them in cast iron in the mould
from a special pattern, converting the casting in a bed of red hematite or at a
red heat and effecting the oxidation of its skin.
2. The improved iron propeller blade or screw propeller, as set forthy
Dated this 30th day of September 1893
PHILLIPS & LEICH
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