US2128268A - Means for securing turbine blades - Google Patents

Description

1938. 2 F-. SMALL ET AL 2,128,268

MEANS FOR SECURING TURBINE BLADES Original Filed May 14, 1931 2 Sheets-Sheet 1 Il'l a I I !%l I I L.F.SMALL., P. FLEE Fig.4' I AAJENNINGS INVENTORS ATTORN Y Aug. 30, 1938. 1 SMALL ET AL 2,128,268

MEANS FOR SECURING TURBINE BLADES Original Filed May 14, 1931 2 Sheets-Sheet 2 L. F. SMALL. P.F. LEE

A.A.JENNINGS INVENTORS ATTOIZ EY Patented Aug. 30, 1938 UNITED STATES PATENT OFFICE MEANS FOR SECURING TURBINE BLADES Lisle F. Small and Paul F. Lee, United States Navy, and Arvah A. Jennings, Vallejo. Calif.

2 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) their lacing without liability to harmful distortion of the blades arising from such spacing and securement.

In the accompanying drawings illustrating the embodiment of our invention, Fig. 1 indicates a top plan view of a portion of a row of turbine blades, which may be either rotor or stator, and our improved tool for spacing the blades the proper equal distance apart throughout the row. Figs. 2 and 3 are opposite side views of the tool shown in Fig. 1.

Fig. 4 is a front elevation view, partially in section, of a portion of a row of blades or vanes and the relation of the spacing tool thereto when employed in spacing the blades or vanes the proper equal distance apart throughout the row.

Fig. 5 is a side elevation view of the tool we have devised for securing each blade or vane in a row to the lacing.

Fig. 5A is a perspective view of the bifurcated portion of the juxtaposed jaws 22, 23 wherein a turbine blade I I is adapted to occupy the vertical space extending through and between such jaws, while the juxtaposed surfaces of the jaws deform the lacing member I4 simultaneously on opposite sides of the blade I I, and

Fig. 6 is a top plan view of the forward portion of the jaws of the tool shown in Fig. 5 relative to some of the blades or vanes to be secured to their lacing.

The subject matter hereof is a division of our copending application Serial No. 537,380, filed May 14, 1931, and patented on April 3, 1934, as Patent No. 1,953,089, entitled Turbine blade lacing and method of making the same, to which reference may be had for a more complete understanding of the invention of which this application forms a part.

In steam turbine practice the blades or vanes are at times subject to wide changes in temperature, and in operation are subjected to high speeds. These exacting conditions render it highly desirable that each blade or vane be secured in place normally without strains. Strains in such blades or vanes we have found most productive of distortion, due to expansion and contraction action by the wide temperature changes. We have always found that such distortion as well as any unequal spacing of the blades or vanes in each of their several rows tends to destroy the static as well as dynamic balance of the rotor, and may lead to interference between the juxtaposed alternate rows of rotor and stator blades or vanes, which interference may result in very great damage to the turbine. These substantial problems are successfully, conveniently and economically solved by the means provided by our present invention.

In the drawings, in which like characters of reference indicate the same parts, III represents, in the ins ance shown in Fig. 4, a portion of a turbine rotor in which the turbine blades or vanes extend radially outward therefrom. It is perfectly obvious to anyone skilled in the art that the turbine stator units each form a circle having the turbine blades or vanes secured at their outer ends thereto and extending radially inward therefrom, and that our invention may be similarly applied to both rotor and stator vanes or blades.

II represents the typical turbine blades or vanes. A preferably round hole is punched or drilled through each blade near its free end, which free end is the outer end in the rotor blades or vanes and the inner end in the stator blades or vanes. Through each of these holes is passed a preferably round rod or tube I4 of a length that will pass through the desired number of blades I I, which number of blades form a group. The blades II of each group are uniformly spaced apart and are then secured in such position by flattening the rod or tube I4 intermediate each blade II. This flattening of tube I4 provides a surface I5 of substantial area between each blade I I and in a plane substantially at right angles to the length of each blade I I and serves the further purpose of tending to confine the greater portion of the motive fluid axially flowing through the turbine between the blades II and the stator or rotor and the tubes I4 and thus tends to minimize the leakage of the motive flu d at the free ends of the blades. The tubes I4 provide adequate strength as well as lightness in weight and at the same time are more readily flattened into broader surfaces I5 which serve the two-fold purpose of securing the properly spaced blades at their free ends and to reduce leakage of motive fluid at the free ends of the blades to an advantageous extent beyond that of the normal member Hi.

There are many blades or vanes in each rotor or stator unit of a turbine, as well as many such units in each turbine, which require many flattenings of the tubes l4. To reduce the assembly and replacement cost of turbines provided with our invention we have devised simple, readily operable, durable and inexpensive means for spacing and securing the normally free ends of each of the blades or vanes. Said means includes a securing tool which is provided with a preferably rectangular bar or body 28 having a portion 2| slidably mounted thereon. From one side and end of body 20 and portion 2| extend respectively jaws 22 and 23, Figs. and 6, whose outer ends are narrow and curved as shown, so that the juxtaposed surfaces of said jaws may extend into the space between the blades l l in the region of tube I l. erably opposite its jaw 23 extends a handle member 24 rigidly attached to or integral with said portion 2 l. A handle member 25 is provided near one end with a plurality of bearing openings 25 extending therethrough, either one of which being adapted to receive a pin 21 projecting from one side of body 20 near its upper or outer end. Said pin 21 may be integral with body 25 or independent thereof and insertable into an opening therein. Adjacent the openings 26 the handle member 25 is provided with a cam surface 28 juxtaposed to and adapted to engage the adjacent surface of portion 2!. A spring 29 connects handle member 25 and jaw 23 so that handle members 24 and 25 are normally held apart, and moved a substantial distance toward each other when engaged by the hand, the outer portions of handle members 24 and 25 being shaped to conform to the hand grip. One of the handle members 24, 25 has a screw 30, or other adjustable means, extending therethrough provided with a lock-nut 3| and whose end is adapted to contact with the other handle member for limiting the movement of said handle members and the distance apart of the juxtaposed surfaces of the jaws 22 and 23, which distance may be conformed to the distance desired between the flattened surfaces I5 of the tube 54. This distance may be varied to any desired extent by the adjustment of screw 30, and fixed by the setting of lock-nut 3!.

When handle member 25 has one or the other of its bearing openings 26 occupied by pin 21 a different leverage is adapted to be exerted by its cam surface 28 upon the sliding portion 2i and its jaw 23.

From preferably opposite sides of jaw 22 extends a pin 32 adapted to serve as a gauge against the sides of blades or vanes l l and insuring substantial uniformity in the relative positioning of jaws 22 and 23 and tube I4 between the blades l I, thus encouraging speedy manipulation of the jaws 22, 23 and the uniform efficiency of their results.

It will be understood that the tubes 54, of a length to extend through the desired number of blades or vanes I! are inserted into the opening, conforming to the size of tube l4 extending through each blade in its group, with a space indicated at 35 in Fig. 1 between the ends of tubes l4, so as to admit, without any impairment, the expansion of the tubes M under the high working temperatures prevailing in turbine practice. The screw 30 being adjusted to afford the desired ex ent to which the tube It. may be flattened, the laws 22 and 23 are then inserted between the Projecting from the side of portion 2| prefblades 5 I to an extent determinable by the pins 32, said insertion not interfering with the spacing means or tool hereinafter described. The handle members 24 and 25 are then gripped until screw 35] limits their further movement, which correspondingly flattens the portion of tube I4 between the adjacent faces of jaws 22 and 23. Such flattening of tube M by jaws 22, 23 so inserted between a pair of blades H would normally spread such pair of blades further apart by the resulting distortion of tube l4, but the portions 43, 44 of the hereafter described blade spacing and holding means, Figs. 1 and 4, engaging the outer surfaces of said pair of blades counteract the transitory strain on said blades occasioned by said flattening and thus precludes such spreading apart of said pair of blades I I. This operation is repeated on the tube 14 between each blade II. This upsets the metal of the tube l4 against each of the opposite surfaces of each blade H and substantially rivets the blades or vanes in their spaced positions due to the increased diameter, beyond that of each hole through each such blade, and which flattened diameter also tends to act as a shroud tending to limit the escape of the motive fluid from the free ends of the blades or vanes.

Where the turbine blades or vanes are long, or temporary space blocks between all of the blades are undesirable preliminary to their being secured in their spaced positions, or where such securement is desired with lesser liability of lateral displacement strain upon the blades, the jaws 22 and 23 are bifurcated as shown in Fig. 6 to slip on opposite sides of a blade ll. Such bifurcated jaws will simultaneously flatten only that portion of tube H on opposite sides of the blade between the bifurcated jaws and will not disturb the diameter of the tube juxtaposed to surfaces of adjacent blades. It will be understood that the blades H that are. each successively secured to the tube or lacing member 14 are the pair of blades II which are then being held in their proper spaced relation by the projection portions 43, 44, of the spacing and holding means hereinafter described. Such securement of blades H to tubes M will subject such portions 43, 44 to substantially less stress, due to the lesser tendency to crowd successively the blade ll away from the portion of the tube being flattened, as heretofore described, than when flattened on one side only of the blade, which latter tends to deflect and place undue strains upon the blades. The bifurcated jaws 22, 23 are preferably curved, as shown in Fig. 6, conformable to the curvature of the blade or vane adapted to occupy the bifurcation.

In flattening each tube l4 without rupturing or unduly distorting the metal of the tube adjacent each surface of each blade I l, the opposite sides of each jaw 22 and 23 is provided with a depression 36 adapted to be positioned upon opposite sides of the center of tube M to more progressively flatten such portion of the tube, substantially as indicated in Fig. 4.

Our invention also provides means for the uniform spacing of adjoining blades and holding them against displacement due to the stresses occasioned by and while they are being laced or secured in such position, as indicated in Figs. 1 to 4. The securing and the spacing-holding means are severally and jointly adapted not to interfere with each other in the efficient closeness of their operative positions in which the spacing-holding means neutralizes the normal tendency to displace the blades by the stresses occasioned by the securing means, and which indicates the relationship and joint functioning of said means, which in the instance shown are several, in the attainment of their unitary result. A pair of arms 40 and 4| are pivoted at their bowed ends by pin 42 and whose opposite ends are respectively provided with curved surfaces 43 and 44 respectively adapted to fit the outer and the inner surface of each pair of turbine blades or vanes, as indicated in Fig. l. Preferably intermediate the ends of said arms 40 and 4! is a screw 45 having an angular head 46 loosely fitting opening 47 in arm 40 and pivotally secured therein by a pin 48 passing through said arm 40 and said head 46. One or more nuts 49 are threaded on screw 45 intermediate the arms 40 and 4|. The free end of screw 45 is adapted to pass through a hole in the arm 4|, in the instance shown in Figs. 1 and 2, and has threaded thereon a nut 59. When the surfaces 43 and 44 of respective arms 40 and 4| are the requisite distance apart the nut 49 is adjusted to contact with the inner adjacent surface of arm 4|, and the other nut 50, which when employed functions as a lock-nut, locks the first mentioned nut 49 in said position, which position is maintained throughout the lacing of the row of blades or vanes.

With the surfaces 43 and 44 respectively of arms 4 and 4| placed on opposite sides of a pair of blades or vanes, preferably in the relative position shown in Fig. 4 and initially on opposite sides of the ends of adjacent tubes 4, the nut 50 is tightened to clamp arm 4| firmly against its adjacent nut 49. This insures the uniform spacing of each pair of blades or vanes. The blades or vanes H are radial, and the fixed uniform distance therebetween in each row is at a fixed point in their length. To readily preserve this fixed point while progressing along the row, each of the arms 40 and 4| is provided with a rod passing through an opening therein and clamped thereto by a screw 6|, one end of each of said rods 6|] is adapted to engage the base ledge of the rotor or stator to hold the arms 40 and 4| at a point in the length of the blades or vanes l I at which the distance therebetween will be uniform throughout the row. The jaws 22 and 23 of the bifurcated lacing tool indicated in Figs. 5 and 6 are then placed on opposite sides of first one and then the other of the pair of blades or vanes, spaced and held by said portions 43, 44, adjacent ends of tubes I4. Said jaws are then clamped together to flatten the tube between them, while said arms 40 and 4| prevent the adjacent turbine blades or vanes from being spread apart as a result of the flattening of the tube between them. The spacing tool is then withdrawn and replaced on opposite sides of the next pair of blades or vanes, including the adjacent one of the pair of blades or vanes previously spaced and secured. When such succeeding pair of blades or vanes are thus properly spaced the aforesaid jaws 22 and 23 are employed to flatten the tube M in a plane intermediate the spacing arms 40 and 4|. This operation is repeated until all the blades or vanes in each row are thus securely laced together.

It will be appreciated by those skilled in the art that turbine blades and their lacing members may be made of such metal or alloy of greater efficiency than has been heretofore possible due to our invention dispensing with the requirement that rivet portions be formed on the outer or free ends of the blades or vanes and providing that the blades may be secured together of uniform spacing without strain of the blades or vanes in either their construction, assembly or replacement, and that more rigid blades or vanes result from our invention which are freer from variations due to temperature changes.

The herein described invention may be. manufactured and used by or for the Government of the United States for governmental purposes without the payment of any royalties thereon or therefor to any or all of the undersigned inventors.

Having now so fully described our invention that others skilled in the art may make and use the same therefrom, what we claim and desire to secure by Letters Patent is:

1. A tool for securing turbine blades or vanes to a lacing member extending thereacross comprising two pairs of jaws, each of a width adapted to enter between turbine blades, the jaws of each pair having opposing surfaces, there being a space intermediate the jaws of each pair adapted to receive a turbine blade, means whereby said jaws may be operated in unison to simultaneously move relatively toward each other to deform therebetween said turbine lacing member, and means associated with at least some of said jaws for definitely positioning the jaws in definite relation to the turbine blades.

2. A tool for lacing turbine blades having a deformable lacing member extending through portions thereof, comprising two pairs of jaws each having opposed faces adapted to engage the lacing member, said faces being of a width adapted to occupy only a part of the space between turbine blades, there being a space intermediate the pair adapted to receive a turbine blade, means whereby said jaws may be operated in unison to move toward each other to simultaneously deform therebetween those portions of said lacing member contiguous to opposite sides of the received turbine blade without subjecting to stress the snugly received or adjoining turbine blades, and means for limiting the placement of the jaws between the blades.

LISLE F. SMALL. PAUL F. LEE. ARVAI-I A. JENNINGS.

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