JPH023005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hollow nozzle blade for a turbine in which a turbine nozzle blade is formed by joining curved plate members. In particular, the present invention relates to a turbine nozzle blade in which two plate members, a curved belly plate and a back plate, are joined together and a rib member is fitted into the inner space thereof.

As is well known, a steam turbine expands the energy of steam using turbine nozzle blades, converts this into interlocking energy, and obtains the rotational force of a generator. Therefore, in order to provide an efficient steam turbine, the nozzle blades must efficiently convert energy, which requires nozzle blades with a complex shape and high precision. In particular, the nozzle blades in the final stage of the turbine have a particularly complex shape due to the flow of a large amount of steam, and require high precision.

As shown in FIG. 1, turbine nozzle blades (hereinafter referred to as nozzle blades) 17 are installed radially across an outer ring 18 and an inner ring 19, and as shown in FIG.
passes between the nozzle blades 17 and the rotor blades (not shown)
gives rotational force to. Commonly used nozzle blades 1
The shape of 7 shown in FIGS. 3 and 4 is adopted. That is, the profile C of the nozzle blade 17 increases in the direction in which the height dimension l of the nozzle blade 17 increases, and the nozzle blade 17 has a complicated shape in which the twist angle θ changes. This complicated nozzle blade 17
As shown in FIGS. 5 and 6, there are two methods for manufacturing the rectangular steel material 10 by machining, and as shown in FIG. Formed abdominal plate 1
One end edge of the back plate 2 is welded to the back plate 2, a piece 3 is welded to the other end edge, and the piece 3 is processed into the nozzle blade contour. However, the machined part shown in FIG. 6 has the disadvantage that many parts are discarded as chips, which not only wastes steel but also requires an enormous number of machining steps.
Moreover, the one in FIG. 8 also has the disadvantage that not only the piece 3 must be processed as described above, but also the outer surfaces of the belly plate 1 and back plate 2 must be processed because welding deformation occurs. Was.

That is, as shown in FIGS. 3 and 4,
As the height l of the nozzle blade 17 increases, the profile C of the nozzle blade 17 becomes larger than the profile _C0 at one end thereof, and the torsion angle θ increases as described above.
also changes. In FIG. 9, the horizontal axis shows the torsion angle θdeg, and the vertical axis shows the ratio of the dimension l to the total height dimension L of the nozzle blade 17, that is, the nozzle blade height ratio l/L. After changing almost to the negative side, it undergoes a complicated change such that it increases from the position l/L corresponding to the inflection point R to the positive side as l/L increases. In addition, in FIG. 10, when the horizontal axis shows the profile enlargement ratio C/C ₀ and the vertical axis shows the nozzle blade height ratio l/L, the outline of the nozzle blade 17 becomes curved as shown by curve A. Change. As described above, the nozzle 17 is formed from a complicated three-dimensional curved surface.

The method for manufacturing this complicated nozzle blade 17 is as follows:
Conventionally, methods have been adopted, such as cutting from rectangular steel, casting and forging, and hollow nozzle blades in which a steel plate is formed into a curved shape and then welded to form the nozzle blade profile.

As shown in Fig. 5 and Fig. 6, the method of cutting a rectangular steel material is as shown in Figs. ₅ and ₆ .
A predetermined nozzle blade 17 is formed by cutting two trapezoidal members and scraping off the hatched portion in FIG. As is clear from the figure, the shaded area becomes chips, and as the nozzle blade 17 becomes longer and the profile becomes larger, the amount of chips increases, deteriorating the product yield of steel products. Furthermore, cutting out a complicated shape requires a large number of machining steps, which not only poses problems in terms of work efficiency, but also has the disadvantage of being expensive.

Solid type nozzle blades made by precision casting or precision forging do not require the above-mentioned machining, but they have the disadvantage of being heavy, inconvenient to handle, and expensive.

The hollow nozzle blade 17 is made by bending a plate member 17a into a curved shape and forming the outline of the nozzle blade 17 on the outer surface of the plate member 17a, as shown in _FIG .
It is formed from L ₂ , L ₄ and a straight portion L ₃ . Since it is impossible to form a contour consisting of these curved portions and straight portions by bending a single plate member, a method is adopted in which the plate is divided into several parts and joined together. Since the curved portion _L1 has a small radius of curvature and is difficult to form, the curved portion L1 is
Use piece 3 instead of L ₁ , and attach abdominal plate 1 to piece 3.
One end edge of the back plate 2 is welded, and the other end edges of the belly plate 1 and the back plate 2 are welded together. 2 with only belly plate 1 and back plate 2 without using piece 3
The above method is used because the split type has large deformation and SR deformation during welding, making it difficult to form the nozzle blade contour. However, as mentioned above, with this method, it is not only necessary to cut out the piece 3 and process it into a predetermined shape, but also the welding line is 3-wire welding consisting of a ₁ , a ₂ , and a ₃ , which causes welding deformation and SR. This has the drawback that deformation occurs and the desired nozzle blade shape cannot be obtained unless the outer surfaces of the belly plate 1 and the back plate 2 are finally processed. Furthermore, if the cross-sectional shape taken along the line X--X in FIG. This results in some disadvantages. As described above, the conventional nozzle blade manufacturing method does not require machining, and it has not been possible to obtain a nozzle blade that is lightweight, inexpensive, and free from problems in strength.

The present invention was devised to solve the above-mentioned drawbacks, and its purpose is to achieve excellent work efficiency without requiring machining, to be lightweight, inexpensive, easy to assemble and transport, and to have excellent rigidity. The purpose of the present invention is to provide a highly reliable turbine buzzle blade.

In order to achieve the above object, the present invention combines two curved belly plates and back plates, joins their respective end edges, and forms a turbine nozzle blade contour on the outer surface. At the same time, a rib member is inserted into the internal space surrounded by the abdominal plate and the back plate so as to be in contact with most of the inside of the cross-sectional shape of the abdominal plate and the back plate, and this rib member is inserted into the internal space surrounded by the abdominal plate and the back plate. It is characterized in that it is fixed to one side and pressed against the other.

Hereinafter, some embodiments of the present invention will be described based on the drawings.

FIG. 13 and FIG. 14 show one embodiment of this, and in this example, the nozzle blade 17
are curved belly plate 6, back plate 7, and rib member 5.
It is formed from. The belly plate 6 and the back plate 7 are each formed into a shape obtained by dividing the nozzle blade 17 into two by pressing or the like. The opposite end edges of the belly plate 6 and the back plate 7 are joined by welding or the like to form a two-line weld of weld lines b ₁ and b ₂ . On the other hand, abdominal plate 6 back plate 7
A plurality of rib members 5 having a contour shape smaller than the nozzle blade contour by the thickness t of the belly plate 6, etc. are fitted into the inner space 11 surrounded by. As a result of the above, nozzle blade contours are formed on the surfaces of the belly plate 6 and the back plate 7. Also rib member 5
Since welding deformation and SR deformation are prevented, there is no need to cut out the surface of the belly plate 6, etc., and
A product with excellent strength can be obtained. Moreover, since the rib members 5 do not fill the internal space and are arranged at appropriate intervals, it is possible to manufacture a lightweight nozzle blade 17.

Next, this embodiment will be explained in more detail.

As shown in FIG. 12, both end edges of the belly plate 6 and back plate 7, which have been divided into two, are welded together by welding lines b ₁ and b ₂ .
When joined by line welding, the belly plate 6 and the back plate 7 will have an arrow mark.
The nozzle blades contract inward as Q ₁ and Q, and the nozzle blade contour formed on the outer surface of the belly plate 6 etc. is deformed. Therefore, even if the belly plate 6 and the back plate are accurately formed by pressing or the like, the outer surfaces must be modified by cutting or the like after welding. On the other hand, Buzzle Wing 17 remains deformed.
If a The outflow angle of the steam changes, and the loss in the next stage blade increases. Also, if you ensure the necessary inclination angle α, the throat T
cannot be secured, the steam passage area becomes insufficient, the amount of energy conversion changes, and the necessary stage efficiency cannot be obtained. Therefore, it is not possible to use the nozzle blade 17 in its deformed state. Also, as shown in Figure 11,
Nozzle blades 17 installed across outer ring 18 and inner ring 19
The vapor pressure k acts like an indicator. For this reason,
Deflection δ occurs in the outer ring 18 and the like. This deflection occurs most often in the nozzle blades 17, which have lower rigidity than the outer ring 18 and the inner ring 19. Therefore, if the rigidity of the nozzle 17 is low and the amount of deflection exceeds a certain value, the gap between the axle (not shown) and the diaphragm increases, and to prevent this, the turbine span must be lengthened.

In order to solve the various drawbacks mentioned above, the above-described rib member 5 is adopted.

As shown in FIG. 15b, the back plate 7 is made by inserting the plate material 13 shown in FIG. 15a into an upper bending die 14 and a lower bending die 1.
5 and is press-molded into a curved shape.
In this case, the upper bending die 14 and the lower bending die 15
Considering the spring back after pressing, the back plate 7
is formed such that its outer surface forms part of the nozzle vane profile.

Next, by punching or plasma cutting, a rib member 5 is formed into a shape smaller than the contour of the nozzle blade by the thickness t of the belly plate 6 and the back plate 7, as shown in FIG. 15c, inside the back plate 7. It is fixed to the surface by welding, etc. Note that a plurality of rib members 5 are arranged at appropriate intervals. Further, it is sufficient to secure the back plate 7 and the rib member 5 by spot welding at several locations.

Although the belly plate 6 is not shown, it is press-formed in the same manner as the back plate 7, and then engaged with the back plate 7 so as to cover the rib member 5, as shown in FIG. 15d.
Then, as shown in FIG. 14, the opposite end edges are joined by welding lines b ₁ and b ₂ . By this joining, the forces indicated by the arrows Q ₁ and Q ₂ shown in FIG. 12 act inwardly, and the rib member 5 and belly plate 6 are brought into pressure contact with each other, so that no gap is created between them. Through the above steps, the hollow nozzle blade 17 shown in FIG. 13 is formed.

Regarding the attachment position of the rib member 5 in the direction of the nozzle blade height l, by attaching one of the rib members to the inflection point R in FIG. The amount can be reduced.

As described above, the rib member 5 eliminates the shrinkage caused when the belly plate 6 and the back plate 7 are joined, and the rib member 5 is inserted into the belly plate 6 and the back plate 7, so that cutting etc. abdominal plate 6 and back plate 7 without
It is possible to form the nozzle blade contour on the outer surface of the nozzle and maintain the required rigidity. In addition, compared to conventional solid type nozzle blades, the weight can be significantly reduced (reduced to about 1/3), and the assembly work is required when assembling and welding the nozzle blades 17 to the inner ring 19 and outer ring 18 shown in Fig. 1. becomes easier, and the second
The throat T shown in the figure can be adjusted accurately and quickly. In addition, when the inner ring 19 and outer ring 18 are cast, the nozzle blade 17 is set in advance and the inner ring 19 etc. are cast, so the weight of the nozzle blade 17 is reduced, which facilitates this setting work and shortens the setting time. can be measured. The above improves the work efficiency of nozzle blade manufacturing. Furthermore, by reducing the weight of the nozzle blades, the diaphragm also becomes lighter, making it easier to assemble and transport.

In the above embodiment, the rib member 5 is welded to the back plate 7 side, but the rib member 5 may be welded to the belly plate 6 side.

FIG. 16 shows another embodiment. A notch 8 is formed in a part of the contour of the rib member 5a that is inserted into the belly plate 6 and the back plate 7, and the rib member 5a
The contact area between the front plate 6 and the back plate 7 is reduced to facilitate pressure contact therebetween.

As is clear from the above explanation, according to the present invention, the work efficiency of nozzle blade manufacturing is improved without the need for cutting work, and it is lightweight, inexpensive, easy to assemble and transport, and has excellent rigidity and reliability. The effect of obtaining a hollow nozzle blade with improved performance is increased.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a turbine diaphragm, Fig. 2 is an explanatory drawing illustrating the steam flow, etc. in a cross section taken along the - line arrow in Fig. 1, and Fig. 3 is an explanatory drawing showing the height shape of the nozzle blade. , FIG. 4 is a perspective view showing the shape of the nozzle blade from the arrow shown in FIG. 3, FIG. An explanatory diagram illustrating the means for manufacturing the blades, FIG. 7 is a perspective view showing the overall shape of the hollow nozzle blade, FIG. 8 is a cross-sectional view showing the conventional means for manufacturing the hollow nozzle blade, and FIG. 9 shows the torsion angle and angle of the nozzle blade. A diagram showing the relationship between the nozzle blade height ratio, FIG. 10 is a diagram showing the relationship between the nozzle blade profile enlargement ratio and the nozzle blade height ratio, and FIG. 11 is an explanatory diagram illustrating the degree of diaphragm deflection. , 1st
FIG. 2 is an explanatory diagram showing the contracted state of the hollow nozzle blade during welding, FIG. 13 is a perspective view showing the hollow nozzle blade of one embodiment of the present invention, and FIG.
15A to 15D are explanatory diagrams illustrating the manufacturing procedure of the hollow nozzle blade of the embodiment, and FIG. 16 is a sectional diagram showing another embodiment. 5, 5a... Rib member, 6... Belly plate, 7... Back plate, 8
... cut portion, 11 ... internal space, 13 ... plate material, 1
4... Upper bending die, 15... Lower bending die, 17... Turbine nozzle blade, 18... Outer ring, 19... Inner ring.

Claims (1)

[Claims] 1. In a turbine nozzle blade of a diaphragm for a turbine, opposing end edges of a belly plate and a back plate which are formed in a curved shape are welded together, and the outer surfaces of the belly plate and the back plate form a contour of the turbine nozzle blade. form,
A rib member is provided in contact with most of the inner side of the belly plate and most of the inner side of the back plate in the cross-sectional shape of the turbine nozzle blade, and the rib member is fixed to either side of the belly plate or the back plate. A turbine nozzle blade characterized by being brought into pressure contact with the other side.