US906400A - Process for attaching turbine-blades to their carrying elements. - Google Patents

Description

S. Z. DE FERRANTI.

PROCESS EOE ATTAGHING TURBINE BLADES TO THEIR CARRYING ELEMENTS.

APPLIOATIOI FILED DEC. 15, 1905. 906,400. Patented Dec. 8,1908.

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S. Z. DE FERRANTI.

PROCESS FOR ATTAGHING TURBINE BLADES TO THEIR CARRYING ELEMENTS.

APPLICATION FILED DEO.15, 1905.

906,400. I Patented Dec. s, 1908 3 SHEETS-SHEET 2.

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S. Z. DE FERRANTI.

PROCESS FOR A'E'IAGHING TURBINE BLADES TO THEIR CARRYING ELEMENTS. APPLICATION FILED DEC. 15, 1995.

906,400. Patented Dec. s, 1908.

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r- 1 1 122 :Grj IK I! Q 1 25 I! 1 E 24. 5 25 Attest: Inventor, 2 0C. '1 77 3 t m SEBASTIAN ZIANI DE FEREANTI, OF HAMPSTEAD, LONDON, ENGLAND.

PROCESS FOR ATTACHING TURBINE-BLADES TO THEIR CARRYIN G ELEMENTS;

Specification'of Letters Patent.

Patented Dec. 8, 1908.

Application filed. December 15, 1905. Serial No. 291,933.

To all whom it may concern:

.] centrifugal force but also tangential force is Be it known that I, SEBASTIAN ZIANI DE I produced.

FERRANTI, a subject of the King of Great Britain and Ireland, and residin at 31 Lyndhurst road,. Hampstead Lon on, N. W., England, have invented certain new and use ul Improvements in QProcesses for Attaching Turbine-Blades to Their Carrying Elements, of which the following is a specification.

This invention relates to the welding of turbine. blades on to the wheels, rings or drums carrying them and also to apparatus used in connection therewith.

The object of my present invention is to improve upon processes at present em loyed for electrically welding turbine bla es to their carrying elements so as to obtain with reater certainty a stronger weld and there- Iore a better attachment of the blade.

A. further object of my invention is to effect the weld with less disturbance of the neighboring metal so as to obtain a smooth passage through the blades.

It has heretofore been proposed to make the disk, ring or drum at the point at which each blade is welded of approximately the same section and conductivit as the blade itself. According to one met od which has been pro osed a wheel of rather less thick ness at t e rim than at the width of the blades istaken and grooves out across the rim thus leaving teeth of the'necessar section projecting therefrom on to whic the blades were welded. This construction left the projecting tooth .on to which the blade was welded of a difierent cross section from that of the blade itself, the metal in the I to this method than according to that described above.

Now the present mvention consists in so forming the ends of the blades and the parts upon which they are welded thata smooth path of any desired form is made and that a weld of great strengthnot only in resisting Referring now to the accompanying drawings which form part of the specification Figure 1 shows a developed edge View of part of a wheel built up of two disks, each provided with angled slits, Fig. 2 being a corres onding section taken on the line A B of Fig. 1, and Fig. 3 a part elevation looking on one of the adjacent faces of a disk; Fig. 4 shows an elevation of a turbine blade having a welding shank or tag; Figs. 5 and 6 c0rrespond respectively to Figs. 1 and 2, the wheel however being built up of three disks instead of two; Fig. 7 is a developed edge view of part of a wheel built up of several disks of equal thickness assembled stepwise as regards the welding teeth. Fig. 8 being similar generally but showing a wheel built up of disks of different thickness; Fig. 9 shows a section through the rim portion of a wheel built up of two flanged disks, Fig. 10 being a similar view of a modified form in which a center disk is added to the above; Fig. '11 shows a multiple wheel built up of component wheels of the type shown in Fig. 9; Fig. 12 illustrates a method of welding in which circumferential grooves are cut in a wheel, while Fig. 12 shows a modification of the wheel shown in Fig. 12 but with V-shaped grooves. Figs. 13 and 14 show the same plan adapted to multistage turbines having 0 lindrical and conical drums respectively;

lg. 15 shows a wheel in which the circumferential rings are burred' or rolled over; Figs. 16 and 17 illustrate a method of welding in which a punched strip is interposed between the turbine wheel and blade; Fig.

16* shows a modification of the method illustrated in Figs. 16 and 17, and in which an unperforated strip is inter osed between the wheelv and the blade. igs. 18, 19 and 20 show wheels built up of disk portions of bending over; Fig. 24 shows a form in-which .the welding takes place-at the bottom of a comparatively dee groove, packing pieces beingjcalked into t is groove between adj a- 20 the center plane of its wheel disk and interin the different figures.

' make the wheel-of two disks, a, a, of slightly more combined width at their rims than the width of the blades, 6.

-'Across one circumferential corner or edge of each wheel disk, (1, I cut grooves or slits, c, by means of a fine circular saw or other con-- venient means, the plane of each cut, ('i.e., the plane of the saw, if a saw is used) being inclined at anangle of 45 or thereabouts to secting this latter plane in a radial line. Consecutive cutsare put at an angle to each other as shown so that when the two wheel disks, a, Which are cut right and left hand,

* are put together, the cuts mark off on the v I root of the blade to edges of the disks a series of parts, d, which approximate in shape to that portion of the e welded to them. The metal, e, of the wheel rim is not cut away between these parts, (1, but is left .standing, the rim thus consisting of partially cut teeth,' (1 and e, alternately disposed, the blades being welded to those marked (1, while those marked 6 are left blank.

The blade ends I form by punching or other suitable means with a shank, f, (see Fig. 4) which may stand out from the body of the blade say one twentieth of an inch.

The blades when, being welded are held in closely fittin jaws shaped to clear adjacent blades theb ade being placed in the jaws so that only the shank, f, rojects. I In cutting the tootl i on to which, the welding takes lace andin proportioning the end of the blade and the conductivity of the jaws which hold it, I am careful to arrange the various sections, sizes, and conductivities so that the tooth on to which welding is tov take lace is at first heated more rapidly than t e shank of the blade. The effect of this and the above described arrangement is that the rincipal heating first. takes place between t e bladeand the tooth, 'i. e., on the surface of the part on to which welding is to be effected. A very .considerable pressure is applied durin the process, and this results, when the a ove arrangement is carried ouig in the actual welding surface being force into the wheel or other part and the surface of the wheel beingl left clean and smooth and untouched by t e disturbing bur which takes place at the weld. Moreover, the forcing into the wheel of the blade shank spreads the metal I wheel instead of being built up of two dlsks,

under the heat of welding and largely fills,

up the saw cuts,in the rim. This has the e ect of allowing a good weld to be made with a fair amount of metal crushed out, which is a very desirable feature. It also makes the welded end of the blade fit the side of the grooves into which it is forced and so greatly supports the blade against side strain. So fullyis this carried out in practice when the blade welding is done according to mypresent invention, that it is possible to hammer over the blades at right angles to their original position without cracking the metal-of the weld, thus showing that great strength and rigidity are obtained accordingr'to the method of my present invention.

' he arrangement above described as typical of my invention may be varied in many ways. Thus according to a modification the a, as shown in Fig. 1, may be formed of threedisks, (see' Figs. 5 and 6)a center one, at, which has slits, 0, out straight across the edge from face to face instead of at an angle and two side disks, 0, disposed one on each'side of the center one, n, to make up the thickness of the finished "wheel as desired, he side disks being right and left hand an having grooves or slits, a, cut in them at anangle, as already described. The section, d, of the face of each tooth on to which the weldingis to be efiected ap roaches even more closely to the section of t e blade according to this method than in the arran ement above described.' The complete w eelgmay 'thus'by an obvious extension of the method of the preceding paragraph be made up of any number of separate disks that is found convenient, provided that the abovedescribed methods are adhered to of'separating those pprtio'ns on to which the wel ing is to take ace. p According to -another method, when the wheel is built up of several disks instead of cutting some or all ofthe slits at an angle, eachdlsk is rovided with slits, such as those shown at 0, i s. 5 and 6, cut strai ht across the edge but 1n this case the wi th of the teeth on to which welding is to take place must be graded and stepped round so as to '115 approximate as closely as possible to the sect1on of the blade. Thus referring to Fig. 7, a

wheel isindicated as built u of six disks, 1',

of equal thickness, the combined thickness of the central four being equal to the widthof the blade shank. Cross slits, s, are cut as mdicated so as to leave broad welding teeth, t, on the two central disks and narrower teeth, at on the second and fifth disks. By assembiing the disks in a stepped manner as shown,

the welding surfaces can be arranged to fol-' low closely the section of the blade. According to a modification of this-method, (see 8) the disks, 0, to which the blades are ed may conveniently be made. of different thicknesses and assembled in a symmetrical manner with the thickest in the middle, the thicknesses of succeeding plates decreasing towards the sides. The disks are rovided with cross slits, s, as before so as to eave welding teeth, t, of different widths. By thus combining disks of different thicknesses with welding teeth of different breadths arranged in a stepped manner, it is easy with straightcross grooving to provide an isolated welding surface which approximates very closely to the shape desired.

According to another modification of the above described "methods, where I desire to weld on to a smooth face of either cylindrical or conical section'and where owing to the moderate speed of the turbine the disks can be made of thin metal, I form the wheel, (see cylindrical portion,the grooves or slits, c,

being cut at an angle so as to isolate portions of the faces where the welding is to be done in a manner precisely similar to that already de- This method, for example, may be carried.

'blades upon wheels, rings, or drums, the

scribed above with reference to Figs. 1 to 3.

into effectwith two disks each of sa one tenth of an inch in thickness and turned over sufficiently round the'periphery to present a surface half an inch in width to correspond to the width of the blades.

The method just described may itself be modified by making the wheel of three thin disks, namely a central one, Z, and two side ones bent over as above described, (see Fig.

10), the, center one being provided with slits, 0, cut straight across the edge as in the form described with reference to Figs. 5 and 6, and the side disks being cut at an angle through a circumferential corner as before. The welding then takes place across the edges of all three disks.

When multiple wheels of this description are built to go on a shaft, the spaces in between the rims (see Fig. 11) may be filled up with circumferential rings, 2, of channel section or the like into which the shrouded ends of the standingv blades, 3, project thus forming an effective guard and preventing undue friction with the working fluid. T he shrouding ring of the running and the standing blades may be attached by any of the well known methods.

According to another method I weld the welding surface of which is cut up into rings by means of circumferential grooves of the desired width and spacing run round about them; but, unlike the arrangement of my previous invention, I leave a smooth face with comparatively narrow grooves cut in them, and also grade the width of the circumferential rings which are left between the grooves in such a way that the surface presented under each part of the blade is approximately of the same width, as the surface at right angles of the blades, i. e., the thickness of the blades, at each part. Moreover, I form the blade with a projecting shank as already described herein, and carry it in jaws as already described. Welding inay then'be most satisfactorily effected between the blade shank and the ring surface, the shank of the blade being forced into this anda smooth path being left between the blades, any little disturbance on the surface, due to the weld, be-

ing flattened by the jaws, which are flush.

with the end of the blade proper and which come in contact with the surface on to which rings, 6, and these may have any desired graded widths to suit the particular case in point as explained above. It is convenient to cutfour circumferential slits, 5, thus leaving three rings, 6, on to which to weld, a central wide one and a narrower one on each side,- the exterior rings against which the cut ends of the blade butt when pressed home not being used for welding.

Referring to Fig. 13, the circumferential groove method is shown applied to both the running blades, 5, and the standing blades, 3, of a multistage turbine having a cylindrical drum, 7, while in Fig. 14, a conical drum, 8, is shown all the blades being provided with shrouding rings; in this latter case, however, I prefer to cut grooves or recesses, 9, into which the shrouding rings on the standing and the running blades may enter both in the conical drum, 8, spectively.

Where I'desire to get a still smoother face, i. e. rim surface, than is obtainedwith the plain circumferential grooving on to which the tag or shank of the blade is welded,-I ma after providing the-wheel or the like and in the casing, 10, re.

wit grooves, 11, as before (see Fig. 15), roll its surface, i. e., the surface of the rings, 6,

formed on the wheel, so as to close the grooves o'ver, although the inner part of the slot remains and so insulates the heat that welding takes place satisfactorily asalready explained. In order to facilitate the burring over of-the surface of the rings, 6, I may make the grooves of V section Fig. 12 instead of" the section shown in Fig. 12. When the burring roller is then applied, the metal s reads out more readily so asto close over t e grooves; after the rolling, the wheel may have its surface machined or ground so, as to finish it.

According to another method I obtain a smoother assage between the root portions of the bla es by means of covering the ringed surface or edge of a wheel prepared as shown in Fig. 12 with a thin strip of metal, 12, continuous or in sections .(see Figs. 16 and 17) out of which holes, 13, are punched of asimilar shape to but larger than the cross section of the tag or shank of the blade. The tags, f, are then put through the punched holes, 13, in the stri direct on to the circumferential rin s; 6, fbr welding. The tag is made rather onger according to this process and the edges of the blades coming down on to the side portions of the strip hold it in position a art from any attachment which isobtaine by the fusing together of the parts in welding.

According to another method Fig. 16, I may cover the circumferential grooves with a ver thin strip of metal, such as that numbere 12 in Fi .16, but without holes punched in it; the wel ing is then effected just in the same way as though the stri was not present. Special care must be taken when work ing according to this method as regards the proportioning of the o osing'sections and the adjusting of the weI mg current so that the parts may be satisfactorily welded together.

According to a modification of the circumferential grooving method, I may form the wheels of disks, 14, put side by side (see Fi 18) with s aces 15, in between them whic corres on to the grooves or slits, 5, already descri ed above. The thickness of metal between the spaces, 15, are so proportioned that their section is'suitable.for welding in relation to the section of the blade at the particular art concerned. I may accomplish this eit 'er b different thic esses as shown in Fig. 18 or I may use disks, 16, of the same thickness as shown in Fig. 19, and group them .together so as to give the effect desired. v 4

The individual disks may either be assembled with intervening packing rings or -d1stance pieces, 17, as shown in Figs. '18 and 19? or the outer disks 18, may be dished as in Flg. 20. I form the blades with shanks and hold them in jaws as already described,

the welding then being effected in a .most

satisfactory manner. Additional disks, 19,

as shown in Fig. 18, may be put on each side .of the wheel in the first instance or afteradopting individual disks of- .their ends out either Sq}? wards; these disks are of thesame diameter as those on which the blade shank is actuall welded but owing to this projecting shan and the cutting away of the other part of the blade end, welding does not take place on to these additional disks and they, merely act as shrouds. Or according to a modified arrangement as shown in Fig. 21,1 may fastenrings, 20, in between the peripheries of the circumferentially grooved wheels in such a manner that a smooth or grooved path is formed circumferentially in between the blade ends thus giving the structure the external appearance of a drum. I may so form and assemble the component parts of i the complete drum accordin to this modification that the welding ta es place .on a conical surface as in Fig. 1 1, the path through the blades taken by the working fluid then expanding in area so as to allow for the change in velocity of the fluid as 1t does work.

I d al with any irregular surface that may be lef after welding by means of stampings, 23, (see Figs. 22 and 23) which are put in between each pair of adjacent blades; the ends of these stampings are turned over I and pressed into grooves, 24, cut round each side of the wheel rim as shown. It will be evident that according to this method the path traversed by the working fluid between the blades may either remain constant in area as in Fig. 13 or expand as in Fig. 14;

According to another method, (see Flgs. 24 and 25), I may form the blades with long shanks, 25, say & inch or thereabouts and weld these shanks on to circumferential rings, 6, formed at the bottom of grooves, 26, running round the drum or the like 1n posltions corresponding to the rings of blades to be welded. In this case the welding aws not only entirely contain the blades but also about 3/16 inch of the blade shank. Welding is then effected as already described on to the projecting rings, 6, within the mainv groove, 26, the edges of the blades left from the cutting of the shank coming down into contact with the surface of the wheel or drum on to which the welding is done.

After the welding 'is complete, packing l i'e'ces, to shape of the blades -on two sides and to the width of themain groove, 26, on the other two sides are pressed'in between the blades into the main groove and are then held in' position by means of calking, the calked packing piece adding to .the tangential stiffness and the weld at the bottom of the groove absolutely insuring the holding of the. blade in osition.

All the blades already describe may have their length and where t e blades are short, as for certain purposes, the smooth ends, 6. 0., the ends remote from the blade carrier,

are or oblique to ples of welded blade carrying members ereinbefore described are to be regarded as illustrative of my invention and not in an way limiting the scope thereof as it is evident that other modifications will readily.

suggest themselves to persons in the art.

What I claim as my invention and desire to secure by Letters Patent is 1. A process for welding turbine blades to their carriers consisting in adjustin the relative heat capacities of the parts to e welded so that the weldin part of the carrier is heated more quickly than that of the blade, and forcing the weld formed between said parts gnderneath the surface of said'carrying mem- 2. A process for welding turbine blades to theircarriers consisting in partially isolating the welding parts of the carrier from the main ortion thereof and forcing the weld forme between the blade and such isolated parts underneath the surface of said set forth. a v

3/ A process for welding turbine blades to their carriers consisting in partially isolating the welding parts ofthe carrier from the main. portion thereof b circumferential grooves and forcing the we d formed between the blade and said isolated parts underneath the surface of said parts, as set forth;

4.- A process for welding'turbine blades to their carriers consisting; in partially isolating the welding parts of the carrier from the main portion thereof by transverse slits, the surparts 'asface so isolated approximating in section to that of the blades to be attached thereto and forcing the weld formed between the blade and said isolated parts underneath the surface of said parts, as set forth.

5., A process for welding turbine blades to their carriers consisting in partially isolating the welding parts of the carrier from the main ortion: thereof and forcing the weld formed between the blade and the said isolated parts underneath the surface of said parts so that the metal crushed out during welding is incorporated with the parts of the a carrier contiguous to said welding parts, as set forth.

6. A process for welding turbine blades to their carriers .consisting in partially isolating the welding parts of the carrier from.the

main portion thereof by cutting transverse slits in. the disk members forming said carrier the said isolated parts cross section to that of the ades to be attached to said carrier and forcing the weld aplproximatingin' formed vbetween the blade and said isolated welding parts underneath the surface of said welding parts. '7. A process for welding turbine blades to their carriers consistin in partially isolating the welding parts of the carrier by spacing the disk members forming'said carrier and forcing the weld formed between the blade and said carrier, underneath the surface of said carrier.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses. I 1

SEBASTIAN ZIANI DE FERRANTI. Witnesses:

, ALBERT E. BARKER, v

BERTRAM H. MATTHEWS.

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