Improvements in and in connection with Steam Turbine Rings of Blades.
Year: 1899

page_text: Date of Application, 10th Aug., 1899
Complete Specification Left, 20th Apr., 1900-Accepted, 21st July, 1900.
Date of Application, 10th Aug., 1899
Complete Specification Left, 20th Apr., 1900—Accepted, 21st July, 1900.
PROVISIONAL SPECIFICATION,
Improvements in and in connection with Steam Turbine Rings of
Blades.
We, The Honourable CHARLES ALGERNON PARSONS, GEORGE GERALD STONEY,
and HUGH FRANCIS FULLAGAR, Engineers, all of Heaton Works, Newcastle-on-
Tyne, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the construction and arrangement
of blades for steam turbines and in mechanism for producing the improved con-
struction.
In one method of construction, the blades are cast into a shrouding of brass or
other suitable metal or alloy; this shrouding may contain one end of the blades
which will then project like the teeth of a comb, or it may cast around both ends
of the blades leaving the middle clear for the passage of steam, or there may be
three or more shroudings in the lengths of the blades. It is preferred in this
combination for facility in casting, to deal with moderately short sections circum-
ferentially though long sections may be used.
In the case of the parallel flow type of turbine, the sections will be annular
sectors forming portions of a complete row or circle of blades.
In the case of the radial flow type of turbine the sections will be like combs
bent laterally to a part of a cylindrical ring.
In either form of turbine it is preferred to let the shrouding into grooves turned
in the drums or dises, and to secure it therein by suitable caulking of the metal
of the shrouding or the metal edges of the grooves or both.
The system of casting preferred is carried out as follows:-Thin strips of sheet
zine or other suitable material are perforated in a stamping press with holes of
the same section as the blades, and at the desired pitch or pitches and angles at
which it is desired that they shall be fixed; these strips are then mounted on a
brass frame of suitable construction, which holds them in their proper relative
position; blades of suitable length are inserted in the perforations the frame and
blades are then placed in the moulding box and rammed up. When the frame is
removed the perforated strip and blades are left in position in the sand and the
impression left by the frame in the sand forms the mould for the reception of the
cast metal shrouding.
The hot metal melts and absorbs most of the zinc strip, and if the strip be of
harder metal it lies against it, or may be caused to adhere to it more or less as
desired the result of the process is in any case a clean casting of shrouding
around the blades, and good passage ways for the steam through the blades.
When cast the section may be machined or pressed or stamped, so as to finish
it accurately to fit the grooves and make it of accurate shape.
The castings may also be treated with acid or pickled in the usual way, to
remove loose zinc or other material.
Another method of manufacture of sections of longer or shorter length or some-
times of complete circles of blades, which we sometimes prefer also enables blade

page_text: sections of single, double or multiple shrouding to be constructed by a mechanical
method wholly, which however, may be supplemented by soldering, brazing, cast-
ing, burning, electric welding, electroplating, or other means.
In the application of this method of construction to blade rings for parallel flow
turbines suitable strips of ductile metal, preferably brass, are bent into a circle
or sector of a circle, on one edge of which teeth of a spiral shape are cut by a
mechanism hereafter described. The form of the teeth is such that when the
blade sections are laid in the grooves and the teeth turned over upon them, the
teeth and blades fit each other closely and form a secure fastening or mechanical
joint. This joint is sometimes made more secure by notching or perforating the
blades before insertion, so as to interlock with the strip. One or more rings or
shroudings may be put upon the blades at the same operation or at separate opera-
tions, and the mechanical joints may be treated by soldering, brazing, burning,
electric welding, electroplating, or in any other convenient way, if desired. The
blade section so formed is inserted and caulked into grooves in the turbine drums
and cylinders.
Sometimes it is preferred to use a wider metal strip, the extra width forming a
tread or ring of brass around the drum or cylinder, so that in the case where these
are made of iron or steel and subject to corrosion, the presence of this strip at the
spot where a steam joint is required, maintains the minimum clearance intact
and tends to prevent an increase of leakage.
This method of formation is equally suitable to the radial flow type, the shroud-
ing material being bent in the other direction and cut on the other face.
The blade material may also he notched by milling, rolling or other means and
the blades inserted and the teeth bent over, securing them before the shrouding
is bent to the desired circle.
In Parsons' Patent No. 14994, 1890, the method of steam packing of the dummy
pistons by longitudinal adjustment of the turbine shaft, is described and claimed.
The formation of a shrouding of the blades in accordance with the present
invention permits of a similar steam packing for both fixed and moving blade
rings and so reduces leakage: for this purpose the shrouding may be formed
with one or more collar bearing surfaces.
In some cases portions of the blade rings, preferably the guide blade rings, may
he left blank, and such portions may be varied so as to reduce the capacity or pass-
age way of such rings of blades, and provide additional means of graduating
expansion in the turbines.
Sometimes we prefer to make the guide blades of our usual form for accelerat-
ing the flow of steam in the tangential direction, while the moving blades are
of the paddle or plano circular form for turning the flow back, the passage ways
in these latter blades being of nearly uniform sectional area, producing a small
change of pressure only in passing through them, and throwing the bulk of the
head or drop in pressure on the fixed guide blades.
The machine for producing the sections of blade rings is constructed with the
object of firstly milling, planing, rolling or otherwise forming teeth in the blank
strip intended for the shrouding. We however, prefer for the parallel flow type
of turbine to bend the strip into a circle of the desired diameter, then to place it
in a groove of a circular table of a milling machine and for multiple shrouding
several strips in concentric or nearly concentric grooves.
Over this table milling cutters of suitable shape operate and cut the teeth auto-
matically or by hand at the desired pitch.
A subsequent operation fills the grooves so cut with blades automatically or by
hand.
Lastly another operation on the same or another machine is performed auto-
matically or by hand, which closes the teeth down by bending them upon the
blades and each other. This operation may be performed by dies of suitable shape
actuated by crank, cam, hydraulic or other suitable means.
The blade material may be formed of our usual drawn sectional wire cut to suit-

page_text: able lengths, notched, perforated, headed, or otherwise operated on to form a
secure mechanical connection with the shrouding material; or the blades may be
formed by drop forging or otherwise in any suitable form to secure good attach-
ment.
In accordance with one modification the operation of the mechanism is as
follows: Brass strips, preferably of rectangular section, are bent into circles
of the desired radii to form the shrouds. They are then cut accurately to semi-
circles or sectors, and placed in the concentric grooves of a circular table. The
table is then made to revolve and a tool or milling cutter turns the upper edges of
the shrouds true, and may also slightly bevel them to suit the dovetail grooves
in the spindles and cylinders.
The strips thus prepared are placed with the turned edge downwards, in the
grooves on the table of the assembling machine, and clamped there firmly by suit-
able eccentric clamps.
The table is rotated at intervals through a small angle corresponding to that
between a consecutive pair of blades. This angle may be varied within wide
limits by means of change wheels, always remaining however an exact divisor
of two right angles. At each position of the table a milling cutter or saw, run-
ning at a high speed approaches each strip and cuts in it a tooth or suitable form.
In advance of each cutter is a vertical punch which descends and acts on the teeth
thus made, successively. A blade is placed in the notch in front of the tooth and
the punch descending closes the latter over the blade, and squeezes it into any
notches etcetera formed in the blade, making a solid joint of the greatest firmness
and the minimum weight. By this method also any stretching or creeping of the
shroud is prevented or corrected and the blades have a determinate position and
accurate width of opening.
Instead of single cutters numbers may be employed on each spindle, the first of
which rough out the tooth and the last finishes to the correct shape.
The spindle may be given a vertical motion with the punch, if only one shroud
is required, but if two or more are required close together the cutters are prefer-
ably given a horizontal motion across the table.
..
Instead of circular cutters straight saws or quills with teeth suitably shaped
and backed off may be used, one stroke of such a quill sufficing to cut a notch.
Further a small variable end motion may be given to the cuiter spindle so that
a single cutter of a simple form may be made to cut teeth with varying contour,
and the opening between the blades rapidly adjusted.
The rings of blades thus assembled are taken from the machine and placed on
the table previously mentioned where a milling cutter or tool turns off the pro-
jecting ends of the blades and the tops of the teeth to an exact gauge.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in and in connection with Steam Turbine Rings of
Blades.
We, CHARLES ALGERNON PARSONS, GEORGE GERALD STONEY, and HUGH FRANCIS
FULLAGAR, all of Heaton Works, Newcastle-on-Tyne, in the County of Northum
berland, Engineers, do hereby declare the nature of this invention and in what

page_text: manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:―
This invention relates to improvements in the construction and arrangement of
rings of blades for steam turbines, and in mechanism for producing the improved
construction.
The object of the invention is to assemble and bind together steam turbine
blades in such a manner as to make a firm ring, semi-circle, or sector which can be
separately finished and readily attached to the turbine cylinder, spindle or case,
thereby permitting the ready renewal or exchange of blades as well as providing
a very firm and mechanical mode of securing the blades to either the rotating or
fixed parts of the turbine.
The first part of our invention consists in assembling and binding together
turbine blades by means of one or more metallic strips provided with notches to
receive the blades, the strips being formed in rings, semi-circles, or sectors, and the
notches closed to grip the blades. This part of our invention consists further in
mechanism for cutting the notches in the metallic strips, and mechanically closing
the said notches upon the blades when inserted.
According to this part of our invention, a number of blades are assembled and
bound together by one or more strips of brass or other metal to form a shroud or
shrouds to the blades, in such a manner as to make a firm ring, semi-circle, or
sector, which can be readily attached to the turbine spindles or cylinders. The
rings or sectors thus made may be machined and finished completely to gauge
before being attached, and the exchange or renewal of the blades is thereby
facilitated.
This part of our invention is equally applicable to steam turbines of the parallel
How type, and to those of the radial flow type. In the former type the blades have
a radial direction, and in the latter they have a direction parallel to the axis.
The second part of our invention consists in casting the blades into a shroud-
ing of brass or other suitable metal or alloy. This shrouding may contain one
end of the blades which will then project like the teeth of a comb, or it may be
cast around both ends of the blades leaving the middle clear for the passage of
steam, or there may be three or more shroudings in the lengths of the blades. It
is preferred in this combination, for facility in casting, to deal with moderately
short sections circumferentially though long sections may be used, and will be
fully described later. Referring now to Figures 1-17 inclusive of the accom-
panying drawings which illustrate the first part of our invention:-
Figures 1 to 10* inclusive, relate to the construction of rings of blades for
parallel flow turbines.
Figures 11 and 12 to radial flow turbines and
Figures 13 to 17 inclusive, relate to the mechanism for cutting the strips, and
inserting the blades.
Figure 1 is a view in perspective of part of a sector of blades for a parallel flow
turbine, in which the blades are held by two shrouds; several of the notches are
shewn without blades in the position before closing
Figure 2 is an elevation of part of a sector of blades also having two shrouds,
as in Figure 1.
Figure 3 is a transverse section through the shrouds on the line A B, Figure 2.
Figure 4 is a view on the flat of a separate blade.
Figure 5 is a bottom plan of the heavy shrouds looking in the direction of the
arrow 1 (Figure 2), shewing the bottom ends of the blades gripped in the notches.
Figure 6 is a plan of the light shroud looking in the direction of the arrow 2
(Figure 2), shewing the upper ends of the blades gripped in the notches.
Figure 7 is a bottom plan, as in Figure 5, but some of the notches are shewn
in their open position before closing down on the blades.
Figure is a similar plan corresponding to Figure 6.
Figure 9 is a longitudinal section through a part of a parallel flow steam turbine,

page_text: shewing the arrangement of double shrouded sectors or rings of blades on the
rotating and on the fixed portions of the turbine.
Figure 10 is a transverse section on the line C D (Figure 9).
Figure 10 is a perspective view of portions of two sectors for the fixed rings
of blades showing one method of supporting the blades at the joints of the shrouds
of each fixed ring.
Figure 11 is a perspective view of a part of a sector of double shrouded blades
as applied to a radial flow turbine.
Figure 12 is a longitudinal section through a portion of such a turbine.
Figure 13 is a side elevation of a machine for cutting the notches in the shrouds
and closing in the blades. The elevation is taken looking in the direction of
the arrow 3 (Figure 14).
Figure 13 is a detail view corresponding to Figure 13.
Figure 14 is a plan of the machine.
Figure 15 is a front elevation.
Figure 16 is a side elevation, looking in the direction of the arrow 4 (Figure 14)
and
Figure 17 is a detail view of the device for adjusting the angular movement of
the table which determines the pitch of the blades.
In carrying the invention into effect, as applied to a parallel flow turbine, suit-
able strips of ductile metal, preferably brass, are bent into a circle or sector of a
circle. On one edge of the strip teeth of a special shape are cut by the mechanism
hereinafter described. The form of the teeth is such that when the blade sec-
tions are laid in the grooves, and the teeth turned over upon them, the teeth and
blades fit each other closely, and form a secure fastening or mechanical joint.
This joint is sometimes made more secure by notching or perforating the blades
before insertion, so as to interlock with the strip. One or more rings or shroud-
ings may be put upon the blades. The blade sector so formed is inserted and
caulked into grooves in the turbine drums and cylinders, or is otherwise secured
to them.
Referring to Figures 1 to 10, inclusive, of the drawings, a, is a heavy shroud
having teeth cut into one side, leaving, however, sufficient breadth of metal uncut
to provide a strong strip to serve as base for the blades; b is a light shroud which
has also cut teeth, but the uncut breadth is less than in ". c, c, c, etc. are blades
which are laid in the spaces between the teeth of the two shrouds, and each tooth
is closed over on the blade held by it. On the right of Figures 1, 7, and 8 teeth
are shewn in the position occupied before closing over; the teeth of the heavy
shroud are lettered e, e, and those of the light shroud f,f: the blades c, c, are
notched at d (Figure 4), and the light shroud engages with the notches as shewn
at Figure 3.
The bases of the blades may be also notched or drilled to increase the grip
between the teeth of the heavy shroud. The teeth e, e, f,f, (Figures 7 and 8)
are formed with a discontinuous outline on the back, so that when bent over and
closed on the top of the blade the convex outline shall then be a continuous curve,
which corresponds exactly with the concave surface of the blade, and fits that
surface. By this means the teeth bear solidly all over the ends of the blades, and
form a strong continuous sector or ring as shewn.
We may cut the notches between the teeth to such a depth that the teeth when
bent over will project above the blades, and the surplus metal may be subse-
quently turned off, leaving the shroud parallel, so as to exactly fill the grooves in
the drums or cylinders.
Both the grooves in the drums and cylinders and also the shrouds, may be dove-
tailed slightly for better security and when the blade rings have been placed in
position, the teeth e are separately expanded by caulking, so as to fill the grooves
and hold the blades tightly. Sometimes we prefer to place a strip of soft metal
alongside the shroud in the groove, and caulk the strip to secure tightness of the
whole structure.

page_text: The sectors or rings are shewn in position at Figures 9 and 10, where h, h, are
drums mounted on the turbine spindle g, and is part of the cylindrical casing
of a turbine The heavy shrouds a of the rotating and fixed blades are fixed
respectively in the rotating drums and the cylindrical casing i in turned grooves
which may be dovetailed to increase the hold The base or heavy shrouds a thus
serve to firmly hold the blades to the drum or casing, while the light shrouds
serve to retain the blade ends in their true relative position to each other. It is
preferred to use for the base or heavy shroud a metal strip, considerably wider
than the blade, as shewn in those figures, and the extra width forms a tread or
ring of metal such as brass around the drum or cylinder. This has the advantage
that when the drums or cylinders are made of iron or steel, and therefore subject
to corrosion, the presence of this strip at the spot where a steam joint is required
maintains the minimum clearance intact and aids to prevent an increase of
leakage.
In parallel flow turbines where the cylinder blade rings are divided at the
junctions of the cylinder, the last blades next to the joints may not be very
securely held, and we prefer to secure these last few blades to one another by
means of pins such as 20, see Figure 10, which may be inserted into holes bored
in the blades when the latter are in position. The pins 20 we prefer to braze or
sweat to the several blades. These few end blades secured together by the pins
may also be brazed or sweated to their respective teeth e to further strengthen
the ring of blades at the joints.
Figures 11 and 12 show an application of the invention to the radial flow type
of turbine; in Figure 11 part of a sector is shewn in perspective, and in Figure 12
the turbine disc and turbine case are shewn in longitudinal section: is the
turbine disc, the spindle, and is the portion of the case carrying the fixed
blades. The heavy shrouds are lettered a, a, and the light shrouds b, b, while the
blades are lettered c, c, c. The parallel flow and radial flow types of steam furbine
are so well-known that it is unnecessary here to describe the path of flow of the
steam in either case.
In some cases portions of the circles or sectors of blade rings, but preferably
of the guide blade rings, may be left solid, that is, without openings between the
blades, and so the area of the passages available for flow of steam may be reduced
to any desired proportion. This is a convenient mode of graduating the steam
expansion between the different sets of blade rings.
Referring to Figures 13 to 17, inclusive, which illustrate a machine for manu-
facturing the rings or sectors of blades; brass strips of suitable section are bent
to the desired radius, cut accurately to semi-circles or sectors, and placed in con-
centric grooves in a metal disc. The disc is placed in a suitable lathe, and the
edges of the strips are machined true, and then they are removed and replaced
with the true edges downwards in the grooves. The disc with the strips is then
taken to the special machine illustrated, which, however, is shewn for simplicity
as adapted to deal with one shroud only.
The machine consists essentially of a circular table w rotated at regular intervals
through a small angle, which angle can be varied by means of change wheels oper-
ated by ratchet gear. The angle is that required between two consecutive blades,
and it is preferably made an exact divisor of two right angles.
The
Above the table is a sliding block which receives a vertical movement from
a crank on a shaft by means of a connecting rod s. Suspended at one end
from the slide block t, and at the other from the frame of the machine, is a frame
or casting carrying a cutter spindle rotated by a belt driven pulley a.
cutter is carried in the slide block end of the said cutter spindle. One cutter
only is shewn. 16 is the disc having concentric grooves, which disc carries the
strip a and is mounted on the rotated table . The cutter spindle frame kis
pivoted from the main frame of the machine at m and it is suspended from the
sliding block by a pin which is free to move in a slot in the end of the cutter.
spindle frame. The cutter spindle frame is thrust down on the pin by the

page_text: spring pressed plunger 1, carried with its spring 2 in the slide block t. At each
descent of the slide block the cutter cuts a tooth or notch in the strip a. The
cutter acts in an approximately radial position and the table can be moved trans-
versely to bring any part of its diameter under the cutter. Attached to the sliding
block in front of the cutter is a punch u, suitably shaped in front to close down a
tooth upon a blade. The blades are placed in position in the notches by hand, and
the punch on descending, closes over each tooth in succession, and thus secures
the blades one by one. Meantime the notches are cut one by one a few teeth
before the punch operates, and so the blades are accurately spaced and fixed in
the strip. The stroke of the slide block punch and cutter is adjusted, by means
of the eccentric block 3 surrounding the crank pin, to be either increased or
diminished to suit the dimensions of the blades and shrouds to be operated on.
The eccentric block 3 is rotated within the connecting rods and fixed in any
desired position to produce the required length of throw. The spring 2 serves
as a relief spring, which yields if the cutter meets with an obstruction. The
pin then moves down in the slot shewn, and so no damage is done. A small
crank is provided with links n which suspend the cutter spindle frame kat
the point 4. The crank and links serve to hold the cutter 7 out of action when -
desired. Handles 5, shewn in dotted lines at Figure 13, and in detail in Fig-
ure 13, are provided to operate the crank and links. The crank pin o works
in slots in the links n to allow freedom of movement of the frame k.
The punch has independent adjustment vertically, horizontally, and about a
vertical axis. It is also arranged to pivot to the block t, at the pin 6, to enable
it to be swung out of action as required.
The shaft in Figure 14 operates the roller lever 9 by means of a cam 30.
This lever is fixed at the top of a vertical shaft 7, and the lever 8, (Figure 16) is
fixed at the bottom. The shaft is pulled in one direction by the spring 14
(Figure 17) which acts on the lever 13, and the position of the shaft at one
extreme of its angular motion is adjusted by the screw 15. The position of this
screw determines the stroke given to the pawl and ratchet device 11. The pawl
and ratchet is actuated from the lever 8 by the rod 10. The ratchet wheel actu-
ates the change wheels 12, and so rotates the table through the desired angle.
The angle of rotation is adjusted by varying the change wheels and also by vary
ing the pawl stroke by adjusting the position of the screw 15. For blade rings
with two or more shrouds, the machine is provided with a corresponding number
of cutters and punches. The punches may be mounted upon saddles on a trans-
verse slide, and worked by eccentrics or cams from a common spindle.
The cutters may be given a horizontal instead of a vertical movement, to enable
one cutter to cut through shrouds placed close together.. But in all modifications
the main features are as hereinbefore described and illustrated in the drawings.
By this method of cutting and closing, inaccuracy produced by creeping or
stretching during cutting or closing is prevented, and the circles or sectors of
blades produced have accurately pitched openings, and a determined width of
opening.
According to the second part of our invention, thin strips of sheet zinc or other
suitable material are perforated in a stamping press with holes of the same sec-
tion as the blades and at the desired pitch or pitches and angles at which it is
desired that they shall be fixed. The blades fixed in these strips are then mounted
on a brass frame of suitable construction which holds them in their proper posi-
tion. The frame, strips and blades are then placed in the moulding box and
rammed up. The frame is removed from the moulding box and the strips and
blades left in position in the sand. The impression left by the frame in the sand
forms the mould for the reception of the cast metal shrouding.
The hot metal melts and absorbs most of the zinc strip, and, if the strip be of
harder metal, it lies against it or may be caused to adhere to it more or less as
desired. The result of the process is in any case a clean casting of shrouding around
the blades and good passage ways for the steam through the blades,

page_text: Referring to Figures 18 to 27, inclusive, which illustrate this second part of our
invention as applied to a parallel flow turbine:
Figure 18 shows a zinc or other strip perforated and ready to receive the blades,
Figures 19 and 20 illustrate in plan and elevation a moulding frame containing
blades and strips and ready to be placed in the mould.
Figure 21 is an inverted plan of the top half of a mould box for moulding the
blade sectors horizontally.
Figure 22 is a plan of the lower half of the same.
Figure 23 is a section of the same moulding box taken on the line W X of
Figure 22.
Figure 24 shows the casting when removed from the mould.
Figure 25 is a vertical longitudinal section of the lower part of a mould box for
moulding the blade sectors vertically.
Figure 26 is a vertical longitudinal section of the upper part of the same.
Figure 27 is a cross section on the line Y Z of Figure 25.
Strips of zinc or other suitable material 21 are perforated with holes 22 and are
then bent to an arc of a circle. Held in place by these strips the blades are placed
in the frame which is made in parts, say, of two circumferential pieces 24 and 25
and two end pieces 26 and 27 all held together by screws 28. The frames with
the strips and blades are then placed in the moulding box and rammed up. The
frames may be either moulded horizontally as shewn in Figures 21, 22 and 23 or
vertically as shewn in Figures 25, 26 and 27. With short blades we prefer to
use the latter method as the sand then holds the blades firmer. In this case the
frames are then withdrawn from the moulds as shewn in Figure 25 and the hot
metal poured into the spaces left by them, forming the casting illustrated in
Figure 24. On the other hand when the frames are moulded horizontally the
parting of the mould lies along the line QRSTUV, Figure 23, and the circum-
ferential parts 24 and 25 are removed in the direction of the arrows shewn in
Figure 22.
The cast shrouds 29 are then machined or pressed to gauge, the solid ends are
cut off and the segments are fitted together and jointed to form complete blade
rings.
The castings may also be treated with acid or pickled in the usual way to
remove loose zinc or other material.
Blade rings with one or many shrouds can be made by substantially the same
process in a similar manner.
We have described this second part of our invention with regard to blade rings
for parallel flow turbines but it is obvious that blade rings for radial flow turbines
can be made in substantially the same manner.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. Assembling and binding together turbine blades by means of one or more
metallic strips, which strips are provided with notches to receive the blades, and
are formed into rings, semi-circles, or sectors, and the notches closed up to grip
the blades, substantially as herein before described.
2. Rings, semi-circles, or sectors of turbine blades, having a shroud or shrouds
in which notches are cut; blades gripped in the notches by pressure of the teeth
in the shroud or shrouds; the base shroud being considerably wider than the
blades and grooves in the rotating or fixed parts of the turbine within which the
shrouds are held, substantially as herein before described.
3. Mechanism for cutting metallic shrouds and closing in the teeth upon the
blades, comprising a rotated table, and oscillated cutter, and a reciprocating clos-
ing punch, all substantially as herein before described.
4. The method of simultaneously cutting metallic shrouds, and closing in the
teeth upon blades, so as to avoid creeping or irregular spacing of the blades, sub-

page_text: stantially as and for the purpose hereinbefore described and illustrated in the
drawings.
-
5. Casting turbine blades into a metallic shrouding by securing them by per-
forated strips and a suitable frame, ramming up the frame, strips and blades in a
moulding box, withdrawing the frame, and pouring the molten metal into the
space vacated by the frame, substantially as herein before described.
6. Moulding the blade rings of turbines by means of a frame adapted to retain
the blades in their relative positions and formed of two circumferential pieces such
as 24 and 25 and two end pieces such as 26 and 27 held together by suitable
means, substantially as herein before described.
7. In the method of casting shrouds for turbine blades as claimed in Claim 5,
a strip of metal such as 21 adapted to hold the blades in position, substantially
e: herein before described.
Dated this 20th day 01 Apr 1
MARKS & CLERK,
18, Southampton Buildings, London, W.C.,
13, Temple Street, Birmingham, and
25, Cross Street, Manchester, Agents.
MARKS & CLERK,
18, Southampton Buildings, London, W.C.,
13, Temple Street, Birmingham, and
25, Cross Street, Manchester, Agents.