US1547838A - Turbine element and method of making the same - Google Patents

Description

July 28, 1925. 1,547,838

C. SSTEENSTRUP TURBINE ELEMENT AND BETHOD OF MAKING- THE SAME Filed March 30, 1923 Im/entor: Christian steenstrup, Mz ;i

His Attorney.

Patented July 2 8, 1925.

UNITED STATES PATENT OFFICE.

'cmus'rmn smnnsrnur, or scnnimc'ranr, miw'Yonx, ASSIGNOB 'ro GENERAL mnornxc comrm, A oonronn'rron or NEW YORK.

TU'BBINE ELEMENT AND METHOD OF MAKING THE SAME.

Application filed March 80, 1923. Serial No. 828,828.

To all whom it may concern: Be it known thatI CHRISTIAN STEnN- srnnr, a citizen of the llnited States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Turbine -Elements and Methods of Making the Same,

of which the following is a specification.

An elastic-fluid turbine depends primarily, for its efliciency upon the proper size and shape of the parts which direct or guide the fluid as it flows from the inlet to the exhaust, and particularly in the case of a multistage impulse-turbine upon the nozzles which are carried by the diaphragms and are commonly called stage nozzles. Briefly stated each diaphragm has a large number of nozzle passages which are closely associated so that the fluid issues therefrom in the form of an annular belt or stream. Each passage has two circumferentially-extending walls and two radially-extending walls, commonly called partitions, each partition being'common to two passages. The diaphragm. structure also comprises a central disk-like member and an outer ring, the ends of the partitions being secured to both parts. The load on these diaphragms due to the fluid pressure thereon is very heavy and for that reason they are usually. made of steel castings. When the nozzle partitions are cast-jointed to the disk and ring. trouble is frequently experienced in the casting operation due to failure of the metal to completely fill the mold, to blow holes, imperfect bonding of the partitions, and to casting strains which in some cases are so great as to crack or distort the partitions. In such a construction there is no fusion of the side edges of the partitions with the cast metal support. To securely fasten the partitions it is necessary to provide them with special anchoring means into which the molten metal flows in the casting operation. Further, it is a very diflicult matter'to finish the circumferent-ially-extending walls or surfaces of the diaphragm between the partitions owing to the smallness of the space between them andto the peculiar shape of the partitions themselves. In some cases the passages are so small that there is' no practical way to finish themand as a result od of making such turbine elements or :lia-

phragms.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the attached drawing, Fig. 1 is a cross-section of a diaphragm for a steam turbine; Fig. 2 is a partial plan view of the same; Fig. 3 is a partial cross sectional view of a slight modification showing special anchoring means; Fig. 4 is a perspective view showing a modified form of nozzle structure; Figs. 5 and 6 show in section modified forms of diaphragm structures; Fig. 7 is a plan view of a diaphragm which is built up of segmental pieces or sections,

and Figs. 8 and 9 are detail views of modified structures.

10 indicates the central member of a cast steel diaphragm for a turbine which is normally subjected to heavy pressure and at times to great changes of pressure and temperature. It is provided with the usual central opening 11 which receives the packing for the- Wheel shaft. 12 indicates a cast steel outer ring or member. Between the central and outer members are the nozzles 13 which serve to direct the steam from one stage of the turbine to the bucket wheel of the adjacent stage. Each nozzle has four walls, two of which extend circumferentially and-two radially as best shown in Fig. 2. 14 indicates a rin which is employed in the process of manufacturing and is afterwards cutaway. It has two concentric shoulders with which the inner and outer members of the diaphragm engage and are held in position thereby. In the ring are two concentric annular slots 15 in which are seated two concentric and properly shaped partitions 16 which form the smooth circumferential walls of each nozzle or nozzle section. The upper edges of these walls or partitions are retained in their proper position with respect to the axis of the diaphragm by a number of short bars or clamps 17 which are slotted to receive-the partitions 16 and are spot-welded or otherwise secured at their ends to the main members of the diaphragm. In the ring-like Walls or partitions 16 are formed slots or openings'which contain short radial partitions 18 as shown generally in Figs. 2 and 4. The ends of these partitions project through the circular walls to form anchors. It will be seen that the nozzle partitions are located in a chamber or container, the bottom of which is formed by thering 14 and the sides by the outer surface of the central part of the diaphragm and the inner surface of the outer member, the top being open. The annular partitions 16 form the outer and inner walls of the nozzle and .being smooth require no further finishing after they are united with the supporting parts.

In order to unite the nozzle partitions with the inner and outer members of the diaphragm I employ a composite material invented by me and which forms the subject matter of another application filed by me of even date herewith Serial No. 628,926. Briefly stated this material comprises for the present purpose a base of smooth, selfpacking metal particles, made of mild steel for example, having spaces between the particles which are capillary in their nature, and a void-filling, fusing or uniting metal such, for example, as boronized copper or copper which has been treated in a hydrogen furnace to remove the impurities. In the best form of the invention the base material is composed of small steel balls or shot and for simplicity the term shot will be employed hereafter.

1 After the parts have been assembled, as shown in Fig. 1, small steel shot are poured into the chambers around the partitions to the desired, level, usually to the-tops of the inner and outer members of the diaphragm. To, facilitate the settling or packing of the shot the structure may be jarred by suitable means such as a pneumatic hammer. On top of the shot in each chamber is placed boronized copper, usually in .small pieces, and of sufficient amount when meltedv to fill the voids between the shot. If there is any excess it may drain out at the bottom through small drains provided for the purpose. The structure is then placed in a closed furnace in which a supply of hydrogen or other selected gas is constantly maintained. The temperature of the furnace is then raised to a point where the copper melts and fuses the diaphragm members, partitions and shot into a unitary structure, said temperature being below the melting points of the shot. After being properly cooled the diaphragms may be machined in the ordinary manner during which operations the temporary ring 14 and the clamps 17 are removed. Since all of the partitions are finished before being assembled nothing the fusing operation is not excessive at any time any strains which may exist in the casting have a chance to and do equalize themselves. The diaphragm parts may be rough-turned before the assembling and fusing operations, but the final machine work should be done afterwards. The composite metal has about the strength of mild steel and for that reason is considerably in excess of that of the uniting metal and because of that fact and also because there is a certain amount of alloyage of the copper and steel shot with the diaphragm members and the nozzle partitions it follows that inner and outer members will be well united or bonded and that as a whole the resulting structure is extremely rugged 14, as by spot-welding or calking at a num-' ber of places around the circumference. The base ring and partitions are then mounted'in a suitable machine, as a boring mill for example, in which the metal forming the partitions is spun to the desired shape. Afterwards the partitions are slotted to receive the radial partitions. It is to be noted that both partitions flare outwardly The purpose of this.

from the base ring. construction is to form a throat for the steamin which there is a gradual conversion of pressure into velocity, andsince the shape largely determines the efficiency of theturbine a very exact relation of parts must be obtained and preserved during the subsequent operations.

Diaphragms constructed in accordance with my invention may be made in one piece or, as is usually the practice, in two pieces,

with the plane of division between them, corresponding to that of the shaft so as to facilitate the opening of the machine.

Fig. 3 shows a slight modification in which either the inner or the outer member of the diaphragm or both are provided with dovetail or equivalent slots 19 to afford additional anchoring means.

Fig. 4 illustrates another construction -clamps 17 as before.

suitable for the nozzle partitions. In this case the temporary ring 14 is provided as before and inserted in the annular slots 15 thereof are short segmental pieces 20 which when assembled form annular members. These pieces may be stamped out of sheet metal with a suitable die and afterwards formed to shape in a forming die. In-the stamping operation slots are, provided for the radial partitions 18. These latter may be uniform in thickness or they may be thicker at the upper or steam receiving end than at the bottom or discharge end. In this construction it is preferable to calk the partitions 20 into the grooves in the base ring but they can be spot-welded if desired.-

The radial partitions being held between the circumferential partitions do not require any additional temporary securing means but there is no objection to providing them if desired. The fact that the steel shot will freely run into the surrounding chamber and will not exert any appreciable pressure means that only very light attachments are i necessary.

Fig. 5 illustrates another form of diaphragm which is composed chiefly of com.- posite material, in this case steel shot, and

-a void-filling material, in'this case, copper.

25 indicates a container made of thin sheet steel which defines-generally the shape of the finished structure. Instead of providing a separate grooved ring 14, the bottom wall of the container is grooved to receivethe nozzle walls or partitions 16. The upper ends of the partitions are held in place by After the circumferential nozzle walls and partitions are mounted in place the container is filled with steel shot and the necessary amount of void-filling copper. After this is done the whole structure is placed in a hydrogen furnace or one containing another selected gas and the whole fused in a solid mass. Fig. 6 shows a similar construction with the exception that instead of using steel shotonly as the base material larger pieces of steel 26.

form part of the filling and which are later fused with the shot. These pieces may be in the form of bars and large enough to form reinforcing means for the diaphragm. In machining these diaphragms either the whole of the container may be machined off or only those portions, which are necessary to complete the same. 1

Fig. 7 shows still another form of the invention as applied to a diaphragm wherein a solid center member 10 is provided and the outer member is composed of segmental pieces 27 which are formed separately. They may be formed by the usual methods or by the fusion method previously described. However they are formed they are placed around the center member in the manner and in elevation in Fig.. 8. -After being assembled on a suitable support, thesegments are temporarily united by a number of short pieces 29 which may bespot-welded or otherwise secured to said sections. Opposite each piece 29 and on the inside of the nozzle between two adjacent radial partitions are thin temporary pieces of material 30 preferably but not necessarily non-metallic, the function of these temporary pieces is to hold the parts together and to assist in forming chambers and prevent the steel shot from running into the nozzle space. The joints at the inner part of the nozzle are similarly provided with pieces'iil for the same reason, the peripheral surface of the disk 10 forming the inner wall of the chambers. After being thusassembled steel shot are poured into the chambers at the joints; and the necessary void-filling copper added at the proper point-s. After this the whole structure" is.

Fig. 9 shows a slightly different form of I diaphragm in which the inner or center member 10 is made solid as before and the outer member is composed wholly of mycomposite material except for the thin wall container and the nozzle partitions. In this case a thin steel band 32 is provided to define the periphery of the diaphragm and also the outer wall of the shot-receiving chamber. The bottom of the chamber is or may be formed of heat-resisting material such as a slab of asbestos 33.

In carrying out my invention it will be observed that the relatively small and .delicate parts areformed as aseparate'strue ture, which means that they can be formed as accurately as conditions require, and that the relatively massive pieces are also formed separately and that all of said parts or pieces are united into an integral whole by composite material. Due to the nature of said material it does not exert any pressure on 'the delicate parts during the manufacturing operation and hence the accuracy of said parts is in no way disturbed and further, that since they are accurately formed work or finishing thereof is required. It follows from this that a substantial saving is effected.

to shape and size, no additional machine Instead of making the nozzles as an integral part of their support they may be formed separately and afterwards bolted or otherwise secured to their support. .Such

nozzles having the-builtup arran emegtof' the walls may be used for the big pressure end of the turbine.

What I claim as new and desire to secure by Letters Patent of the United States,

1. In a turbine element, the combination to form fluid-directin means with a composite metal support t erefor comprising a base of self-packing metal particles and a metal of lower melting point than the base which fills the voids in said base and intimately unites the particles and the directing means, the strength of the composite support being greater than that of the uniting metal.

2. In a, turbine element, the combination of separately built up fluid-directing means comprising thin metal parts which define the fluid passage or passages with a: composite metal support therefor comprising steel shot and void-filling copper which latter intimately unites the shot and fluiddirecting means, the strength of the support being greater than that of the copper.

3. In a turbine element, the combination of fluid-directing means comprising annular walls which form the circumferential boundaries of the fluid passages, radially-extending partitions which form the other boundaries of the passages, and a composite metal support for said means comprising a base material of self-packing metal particles and a metal of lower melting point than the base material which fills the voids in the said base material and intimately unites the same with the said fluid-directing means,

said composite support having a greater strength than the uniting metal.

4. In a turbine element, the combination of fluid-directing means comprising a structure built up of sheet metal parts, the walls of said parts forming the guiding surfaces for the fluid, and a carrier therefor of com posite material which backs up and supports the parts comprising a mass of selfpacking metal particles having voids of a capillary nature between them, and a voidfilling metal which has a'lower melting point than the particles and which intimately unites said structure and the particles, said composite material having a greater strength than that of the void-filling metal.

5. In a turbine element, the combination of fluid-directing means comprising a separately built up structure made of sheet metal, the walls of which define the guiding surfaces for the fluid, a supporting member, and a body of composite material forvsupporting the sheet metal parts and i for uniting the same with the member and comprising a mass of self-packing metal particles having voids of a capillary nature between them, and a void-filling metal which has a lower melting point than the particles and which unites said articles, structure and member, the strengt of the composite material being greater than of the v0-id-filling metal.

6. In a turbine element, the combination of fluid-directing means comprising a separately built up structure, inner and outer supporting members, and means for uniting said structure with the members which means comprises a body of composite material made up of self-packing metal particles having voids of a capillary nature. and a void-filling metal which has a lower melting point than the particles and which intimately unites the particles with the structure and'the members, the composite material having a greater strength than the void-filling metal.

7. .In a turbine element, the combination of a fluid-directing means comprising a built up structure, a central disk member,

an outer ring member, said structure and members being in spaced relation, and a filling for the spaces between the structure and members comprising steel 'shot having voids of a capillary nature between them, and a void-filling metal having a lower melting point than the shot, which intimately: unites said shot, structure and members, the said filling having a strength greater than that of the void-filling metal.

8. In a turbine structure, the combination offluid-directing means comprising circular members which form the circumferential al shot.

9. In a turbine structure, the combina tion of a nozzle having concentric walls and radial partitions, said walls and partit ons defining fluid passages, a carrier therefor, and composite metal for uniting the nozzle and carrier which comprises a base of hard-packed metal particles and an added metal of lower melting point than the base which fills the voids in said base l and intimately unites the particles, nozzle and carrier into an integral structure,

the said composite metal having a strength substantially greater than that of the added metal.

10. The method of making turbine ele- 'ments which comprises building up a thin metal structure having spaced. side members and partitions which extend across the space between the members, said members and partitions defining fluid-conveying passages,

mounting said structure in definite relation to a support, and in spaced relation thereto, filling the space between said structure and the support with self-packing metal particles having voids of a capillary nature between them, adding a metal of lower melting point than the particles in suflicient amount to fill the voids, placing the elements thus formed in a closed furnace in which a supply of selected gas is maintained, and subjecting the same to a temperature sufficiently high to 'cause the void-filling metal to fuse the said structure and particles together.

11. The method of making turbine elements which comprises assembling thin metal pieces into a structure of the desired size and shape, placing said structure between inner and outer annular supporting members which are separated therefrom by chambers, filling the chambers with metal shot, adding metal to the chamber which has a lower melting point than the shot and in sufiic-ient amount to fill the Voids between the shot, placing the element thus formed in a, closed furnace in which a supply of selected gas is constantly maintained, and subjecting the same to a temperature sufiiciently high to cause the added metal to melt andfuse the metal pieces and the balls into an integral whole.

12. The method of making turbine elements which comprises separately forming the inner and outer members, separately forming the fluid-directing means of thin metal with the walls thereof shaped to'define the finished fluid-conveying passages, placing said means in spaced position between the two members, temporarily uniting said members and means to preserve the desired relation of the Parts, filling the spaces between the members and meanswith steel shot, adding copper in sufficient amount to fill the Voids between the shot, and placing the element thus assembled in a closed furnace in which a supply of a selected gas is constantly maintained, and subjecting the same to a temperature sufliciently high to cause the copper. to fuse the parts into an integral whole.

13. The method of making turbine elements which comprises mounting a'pair of contric metal members on a temporary ring, forming said members to the desired shape by a spinning operation, slotting said mernbers, mounting partitions in the slots, surrounding the members with a composite material comprising a base of self-packing metal particles, having Voids of a capillary nature, adding a void-filling metal which has a lower melting point than the particles, placing the structure thus formed in a closed furnace to which aselected gas is supplied, subjecting the same to a temperature sufficiently high to cause the added metal to melt and fuse the parts together, and removing the temporary ring.

In witness whereof, I have hereunto set myhand this 29th day of March, 1923.

CHRISTIAN STEENSTRUP.

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