US2157679A - Method of making turbine elements - Google Patents

Description

y 9, 1939- H. F. SCHMIDT 2,157,679

METHOD OF MAKING TURBINE ELEMENTS Fi led Dec. 31, 1957 2 Sheets-Sheet l WITNESSES: INVENTOR w ,YM F7 Q- a I HENRY F SCHMIDT. *MT /M I BY an no, R i

ATTORNEY H F. SCHMIDT May 9, 1939.

METHOD OF MAKING TURBINE ELEMENTS Filed Dec. 31, 1937 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patented May 9, 1939 PATENT OFFICE METHOD OF MAKING TURBINE ELEMENTS Henry, F. Schmidt, :Lansdowne, Pa., assignor t0 Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 31, 1937, Serial No. 182,664

3 Claims.

This invention relates to steam turbines and more particularly to nozzle devices therefor.

In single-row impulse turbines of the re-entry type, steam leaving the blades after one step of velocity energy abstraction is re-directed one or more times, usually once for one or more further step or steps of energy abstract by the same row of blades. To accomplish this, use is made of a reversing chamber, and my invention has for an object to provide an improved method of making reversing chambers for this purpose.

A particular object of my invention is to provide an improved method, permitting of economy of construction, the method comprising milling the desired groove or grooves in a straight or flat blank or block and then bending the grooved block to the desired curvature; and, more particularly, my invention has for an object the production of reversing chambers in this way.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings forming a part of this application, in which:

Fig. 1 is a plan view of a reversing chamber made in accordance with my invention, shown in its association with a set of blades and a nozzle;

Fig. 2 is a perspective View of the reversing chamber block after initial shaping;

Fig. 3 is a view similar to Fig. 2 showing a first fluid passage in the block;

Fig. 4 is a view similar to Fig. 3 with a second fluid passage added to the block;

Fig. 5 shows the structure of Fig. 4 provided with bolt holes;

Fig. 6 is an exploded view of the completed reversing chamber, the cover therefor, and the bolts for connecting the chamber and cover; and,

Fig. 7 is an elevational view of one means for curving the reversing chamber block.

Fig. 8 is a perspective View of a modification.

Referring to the drawings more in detail, in Fig. 1, there is shown diagrammatically the important elements of a re-entry turbine comprising a nozzle In which converts pressure energy of steam into velocity energy and directs the highvelocity steam for passage through the blades ll carried by rotor l2 to effect the initial stage of velocity energy abstraction. Steam leaving the blades after the first step of energy abstraction'is redirected by the nozzle chamber at l3 for passage again through the blades to effect a further step of velocity energy abstraction. Usually the reversing chamber comprises a block l3 having a convex upper face l4 conforming to the blade row curvature and a side edge I5 extending parallel to the exit edges of the blades. The block has grooves 11 and I8 opening through the upper face thereof and having their ends opening through the adjacent side edge [6. A plate 2| is attached to the block to cover the grooves in order to complete the steam passages. The passages are curved suitably to receive steam from the blades, to change the direction thereof, and to re-direct it for passage through the blades; and such passages, or at least the end portions thereof, have a depth suitable to the height of the blade passages. The block is provided with tapped openings 22 and registering with openings 23 in the cover for the reception of screws 24 for attaching the cover to the block, and the block and the cover have registering openings 26 and 21 extending therethrough for the reception of means for supporting the reversing chamber from stationary structure of the turbine.

It is customary practice to cast the block with the grooves therein, to machine the convex top face and the side edge thereof, and to mill out the grooves to finished dimensions. Because of the curvature of the block, both machining of the top face and milling of the grooves are complicated and special cams or templets have to be provided for each size of reversing chamber, these things contributing to high cost of construction. My invention is concerned not only with more economical production of reversing chambers, but with production from mechanically worked or rolled metal, with the result that casting imperfections are entirely avoided.

In accordance with my invention, as shown in Fig. 2, a blank A is cut from suitable bar stock, the faces and edges thereof being sufiiciently smooth as not to require machining. Next, a suitably curved reversing groove or channel [1, Fig.

' 3, is provided by a single cut with an end miller,

using a milling machine of standard design. If desired, a second groove or channel l8 may be milled in the block A, in a similar manner, the grooves l1 and I8 joining to form the larger groove I9 shaped, as is well known in the art, to direct the steam for further impact on the blades. The blank A is provided with a plurality of holes 22 and 26, the holes 22 being tapped.

After having formed the grooves or channel, and the openings in the block 13, and having drilled and tapped all holes, the block is bent by rolling or by pressing so that its faces are curved about the same axis, the milled grooves or channels preferably extending through the convex face, as shown in Fig. 6. In Fig. 7, there is illustrated one means for bending the block, the means. consisting of a die 28 and a ram 29, the former having an upper concave surface 3! and the latter having a lower cooperating convex surface 32. In Fig. 7, the dot-and-dash lines indicate the blank prior to the bending and the full lines show the blank bent to final shape.

A cover 2| of thin sheet metal having holes 23 and 21 and having the same outline as the curved blank or block !3, is curved to conform to the convex surface thereof and to cover the passages aforesaid.

Instead of first giving the blank the desired peripheral shape and then milling the passages, I may mill the passages for a plurality of reversing chambers at spaced points in the surface of a bar, and thereafter roll or bend the entire bar to the desired curvature, after which the bar may be sectioned to provide individual curved blanks or blocks, each with its grooves.

While screw and bolt openings are preferably provided before bending, it will be apparent this may be done afterwards if desired, the principal feature of the invention being machining a straight block followed by bending thereof.

From the foregoing, it will be seen that all steps of my method are performed on stock material with the use of ordinary or standard type machine shop equipment, thus eliminating material items of expense, such as, pattern making, casting, special milling machine design and construction, etc.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore,

that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. A method of producing reversing chamber structures for fluid turbines comprising providing a fiat blank having opposite faces and end and side edges, milling a curved channel in the blank and through one of its faces, the channel having its ends opening through one side edge of the blank, bending the blank so that its faces are curved about the same axis, forming a cover for the curved channeled face, and attaching the cover to provide a structure having a reversing chamber formed by the channel and the cover.

2. A method of producing steam passage structures for turbines; comprising providing an elongated fiat strip of metal, machining one or more longitudinally extending passages of uniform depth at spaced intervals therealong in a surfacethereof, bending said metal strip uniformly so that said passages are in the convex surface thereof with their bottoms in a plane curved longitudinally of the strip of metal, and separating the metal strip transversely into a plurality of steam passage structures.

3-. A method of producing a fluid turbine reversing chamber; comprising providing a flat piece of metal with a longitudinal channel of uniform depth in the upper surface thereof with both ends of the channel opening through a side thereof, bending said metal piece uniformly so that the channel is in the convex surface with its bottom in a plane curved longitudinally of said channel, and attaching a curved cover plate to the convex surface of the metal piece.

HENRY F. SCHMIDT.

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