Improvements in the Construction of Steam Turbines.
Year: 1893

page_text: Date of Application, 30th Dec., 1893
Complete Specification Left, 1st Oct., 1894-Accepted, 17th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Steam Turbines.
I, JOHN SMITH RAWORTH, of 24 Kirkstall Road, Streatham, in the County of
Surrey, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to improvements in the construction of steam turbines of
the impulse type, and has for its object the manufacture of the turbine wheel in
such a manner as to ensure a firm and permanent structure with economy in working
and in prime cost.
Steam turbines of the type to which my invention applies, involve the principle
of the Pelton water turbine in which the motive fluid impinges successively on a
number of curved buckets each of crescent form, whereby the fluid after impinging
on the bucket is turned in a contrary direction and delivered with the least possible
circular or tangential velocity.
In steam turbines the velocity of rotation is so high-from ten to forty
thousand revolutions per minute-that the chief problem to be solved is the
construction of the wheel in such a manner that it may fulfil the condition of
economical generation of power from a jet of steam and not be destroyed by
centrifugal force.
To this end I construct the buckets of suitable metal such as steel, stamped to
the required shape, that is to say crescent shape in cross section and forming say
about 120° of a cylinder, or spoon shaped. I prefer the spoon shape as it is stronger
and more effective. It is obvious that the buckets may be made of the required
form by cutting out of the solid, but they may be made of greater strength and at
less cost by stamping. The buckets thus formed are then secured at equal distances
apart upon or to one or more rings to which they are united as for example by
soldering, brazing or electric welding so as to permanently connect the various
parts together and form a wheel consisting practically of one piece. For this
purpose according to one construction I provide the shank of each bucket with a
hole which by preference is of rectangular shape with semicircular ends and which
is arranged with its principal dimension in a radial direction, and I thread the
buckets thus formed on to a metal ring having a slit in it. After all the buckets
have been threaded onto the ring, electrically weld the ring so as to make it
I then pack
continuous and equally strong at every point in its circumference.
the buckets at equal distances apart and solder or electrically weld the whole
together so as to form practically one piece. According to another construction
instead of threading the buckets on a ring, the same or a similar result is obtained
by using two rings let into recesses formed in opposite sides of the buckets, the
buckets and rings being then soldered or welded together as before.
A turbine wheel constructed as described, may be mounted on a suitable base
by soldering or electric welding, or may be clamped between two metal discs or
cheeks.
A
1000

page_text: Improvements in the Construction of Steam Turbines.
I, JOHN SMITH RAWORTH, of 24 Kirkstall Road, Streatham, in the County of
Surrey, Engineer, do hereby declare the nature of this 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 the construction of steam turbines of
the impulse type, and has for its object the manufacture of the turbine wheel
in such a manner as to ensure a firm and permanent structure with economy in
working and prime cost.
Steam turbines of the type to which my invention applies, involve the principle
of the Pelton water turbine in which the motive fluid impinges successively on
a number of curved buckets each of crescent form, whereby the fluid, after
impinging on the bucket, is turned in a contrary direction and delivered with
the least possible circular or tangential velocity.
In steam turbines the velocity of rotation is so high-from ten to forty
thousand revolutions per minute-that the chief problem to be solved is the
construction of the wheel in such a manner that it will fulfil the condition of
economical generation of power from a jet of steam and not be destroyed by
centrifugal force.
To this end I construct the buckets of suitable metal such as steel, stamped to
the required shape, that is to say crescent shape in cross section and forming say
about 12 of a cylinder, or spoon shaped. I prefer the spoon shape as it is
stronger and more effective. It is obvious that the buckets may be made of the
required form by cutting them out of the solid, but they may be made of greater
strength, and at less cost, by stamping. The buckets thus formed are then
secured at equal distances apart upon or to one or more rings to which they are
united, as for example by soldering, brazing or electric welding, so as to
permanently connect the various parts together and form a wheel consisting
practically of one piece.
In the accompanying drawings,
Fig. 1 shows in cross section a turbine wheel constructed according to this
invention.
In this case each of the buckets a, shown as of spoon shape, has a shank a
of wedge shape in cross section and formed with a hole a having its principal
dimension in a radial direction. The buckets with shanks thus formed are
threaded on to a metal ring having a transverse slit in it to enable this to
be done. After all the buckets have been threaded onto the ring, I electrically
weld the two ends of the divided ring together so as to make it continuous and
equally strong at every point in its circumference. I then pack the buckets at
equal distances apart by distance pieces placed between the shanks of the buckets
and partly embracing the ring , and solder or electrically weld the whole
together so as to form practically one piece.
Fig. 2 is a similar view to Fig. I showing another construction of turbine
wheel according to this invention wherein, instead of threading the buckets on a
divided ring the same or a similar result is obtained by using two rings b¹³ let
into recesses a³ formed in opposite sides of the shanks a' of the buckets, the
buckets and rings being then soldered or welded together as before.
A turbine wheel constructed as described, may be mounted on a suitable case
by soldering or electric welding; or it may be mounted upon a boss or sleeve c
on a shaft das in each of the examples shown, by clamping it between two
centrally perforated metal discs or cheeks e e' that are forced tightly against
the opposite sides of the wedge shaped shanks « by nuts ff screwed on the

page_text: boss or sleeve c so as to firmly fix the wheel on the latter and prevent any
liability of parts of the wheel being thrown outward by centrifugal force.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The construction of the wheel of a steam turbine in the improved manner
hereinabove described, that is to say by securing the shanks of the buckets
previously stamped or otherwise made of the required form, at proper distances
apart upon one or more metal rings and uniting them to the said ring or rings, as
by soldering, brazing or electric welding, so as to permanently connect the various
parts together and form a wheel consisting practically of one piece as set forth.
2. The improved wheels for steam turbines constructed and mounted substantially
as hereinbefore described with reference to and shown in the drawings annexed.
Dated this 1st day of Notobon 1401
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.