JPS5939906A - Nozzle diaphragm - Google Patents

Abstract

PURPOSE:To perfectly release residual stress through steress removing annealing by forming the unwelded part in the intermediate part in the axial direction on the welded part between a nozzle plate and the outer or the inner ring of a diaphragm. CONSTITUTION:A nozzle plate 10 is inserted into a supporting hole 13 formed on inside and outside supporting plates 11 and 12, and the both plates are joined 14. The supporting plates 11 and 12 are joined through welding 17 with the respective inner and the outer rings 15 and 16 of a diaphragm. In this case, an unwelded part 18 is formed in the intermediate part in the axial direction on the nozzle plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention is applicable to, for example, a nozzle dianorum of a steam turbine.

[Synopsis of the invention] Fig. 1 shows a nozzle dianorum of a conventional steam turbine. In Fig. 1, the reference numeral 1 is sandwiched between an annular inner support plate 2 and an outer support plate 3. The nozzle plate is shown, and an inner support abutment plate 2 and an outer support abutment plate 3 are welded to a diaphragm inner ring 4 and a diaphragm outer ring 5, respectively, by arc welding, for example.

That is, in general, the nozzle diaphragm is constructed by arranging an inner support plate 2 and an outer support plate 3 concentrically, as shown in FIG. After inserting both ends of the nozzle plate 1 into a large number of support holes 6 punched in each direction, as shown in FIGS. 3 and 4, the ends of the nozzle plate 1 and the inner support plate 2 J3 are inserted.
and the periphery of the support hole 6 of the outer support plate 3 are welded and fixed by, for example, arc welding 7 to form a nozzle plate shaft 8, and as shown in FIG. The support plate 2 is fitted to the outer periphery of the diaphragm inner ring 4, the outer support plate 3 is fitted to the inner periphery of the diaphragm outer ring 5, and these contact parts are connected by arc welding 9. There is.

[Problems in the Background Art] However, in such conventional nozzle dianorams, the strength of the welded part, which is a strength element of the nozzle dianoram, is grasped in 1-min, and the dimensions of the welded part are The residual stress caused by stress relief annealing after welding was not released within 1 minute and remained as it was (J3).

This residual stress that is not released by the stress relief annealing is released during the operation of a steam turbine, for example, and the nozzle die is deformed to 7 norams. There is a possibility that vibration of the turbine and contact heat may cause bending of the [-1-ta].

(Purpose of the Invention) The present invention has been developed to deal with such conventional circumstances. At the same time, we provide a highly reliable nozzle diaphragm with sufficient strength.

[Summary of the invention]

That is, the present invention provides a nozzle diaphragm in which one of the plates that sandwich the nozzle plate is welded to the dianoram outer ring and the other to the dianoram inner ring. This is a nozzle diaphragm characterized in that an unwelded part is formed in the middle part of the nozzle diaphragm.

[Embodiment J of the Invention The details of the present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 5 shows a nozzle diaphragm according to an embodiment of the present invention, and in the figure, reference numeral 10 indicates a nozzle plate.

This nozzle plate 10 is held between an inner support plate 11 and an outer support plate 12, and both ends i of the nozzle plate 10 are inserted into support holes 13 formed in the inner support plate 11 and outer support plate 12, respectively. and are welded together 14.

The inner support abutment plate 11 and the outer support abutment plate 12 are welded and joined to the outer peripheral surface of the diaphragm inner ring 15 and the inner peripheral surface of the diaphragm outer ring 16, respectively.

Therefore, on both sides of the width 1 in the 111 direction of the diaphragm outer ring 16 or the diaphragm inner ring 15 of the nozzle plate 10, there is a bonded part with a length λ1113°1 and a bib 2, and in the middle part there is a bonded part with a width ρ.
A welded unwelded part 18 with a length of 3 is formed (there is a width J23 of this welded unwelded part 18).
The width β3 of the nozzle plate 10 is set to be 0.3 to 0.7 times the full width of the nozzle plate 10. If it exceeds 0.7 times, L1 is easy to break, and the stress intensity factor increases rapidly, making J1 always easy to break.

Since it is determined by the strength of the welded part of the nozzle diaphragm (the welding depth of the welded part, that is, the welding TI), the dimension β3 of the unmelted mold part 18 of the nozzle plate 10 is determined by the strength of the welded part of the nozzle diaphragm. It has a strong meaning that has been learned by hand. Further, since the nozzle plate 10 is inserted into the support holes 13 bored in the inner support plate 11 and the outer support plate 12, a gap exists between the support hole 13 and the nozzle plate 10, Mutual interference between this gap and the gap formed in the unwelded portion 18 of length J23 also has a significant effect on the strength of the welded portion.

The inventor has determined that the dimension J! of the unwelded portion 18 of the nozzle plate 10! , 3 and the strength of the welded part through testing and analysis using the finite element method.As a result, as shown in curve a shown in FIG.
length (ratio of 3 and full width of nozzle plate 10 (3/l- is 0
．． 7 or more, the difficulty of breaking the welded part tip of the nozzle plate 10 due to the gap formed between the support hole 13 of the outer support abutment plate 12 and the inner support abutment plate 11 and the nozzle plate 10. It has been found that the stress intensity factor, which indicates

In addition, in Fig. 6, the horizontal axis shows the rectangle of λ3/l-,
The stress intensity factor K at the notch tip is plotted on the vertical axis.

In addition, in general, nozzle die (nozzle die) is used to determine the welding area mentioned above.
The decrease in rigidity of the nozzle 11 is important, and based on this, the appropriate welding amount of j2 + / L, β2 / [-, that is, 111 of i 3 / L can be determined.

However, the curve shown in FIG. 7 is a graph showing the relationship between J23/1- and the deformation m of the diaphragm inner ring 15.
The horizontal axis shows the value of fl s / L, and the vertical axis shows the value of nozzle plate 1.
The length of the unwelded part 18 of 0 (deformation ω when 3 is zero is 1.
What is the rate of increase in the amount of deformation when it is set to 0?

As is clear from this figure, (the value of 3/L is 07 or more,
In other words, when the values of β1/' and fl2/L become 0°15 or less, the amount of deformation becomes 1.5 times or more, and the probability of contact between the nozzle diaphragm, which is a stationary part, and the rotor, which is a rotating part, is high. Therefore, it is necessary to keep the value of β3/l below 0°7.

The reason why the ratio of the length β3 of the unwelded part 18 of the nozzle plate 10 to the total width of the nozzle plate 10 is set to 0.3 or more is to take into account primary creep deformation due to residual stress. .

That is, in general, stress relief annealing is performed at a temperature 10 to 20 degrees Celsius lower than the tempering temperature, and at a weld depth of 25 degrees per quarter.
Although the welding is carried out at a certain rate, residual stress remains in the weld C
If this occurs, this residual stress is released during operation of the steam turbine and appears as deformation of the nozzle diaphragm, causing the nozzle diaphragm in the static 1F section and the rotating section L
This will bring about contact with the evening.

In other words, the amount of deformation of the nozzle diaphragm is determined by two factors: the amount of deformation due to the release of residual stress and the deformation due to the acceleration of creep deformation in the primary creep region, so the gap between the rotating part and the stationary part must be considered. Then, the residual stress value needs to be 5 kg/m or less.

Generally speaking, the stress relief annealing holding time is set at 1 hour per welding depth of 25.4 mm, but if the structure is complex like a nozzle diaphragm, the heating time may be longer than this. need to be retained. However, such long-term heating results in a decrease in the strength of the material used for the nozzle diaphragm, so in order to reduce the strength of the material, the residual stress from certain culm welding is often used as it is. In this case, J > tJ during operation.
The deformation of the nozzle 77 ram will further increase.

The curve C shown in FIG. 8 shows the relationship between the residual stress value determined by the inventor based on the experimental phase solution and the linear Lino deformation d. The horizontal axis shows the residual stress value. The vertical axis shows the first rhezo deformation after 1) 4500 hours at 500°C.

As is clear from this figure, when a residual stress of approximately b kg/'*M remains, the cleavage curve sharply increases.

The curve d shown in FIG. 9 is the J
It shows the relationship between the value of 2+/L or Jl 2/L and the residual stress value, where the horizontal axis shows the value of (1/L or (2/L), and the vertical axis shows the residual stress value. There is.

This figure clearly shows J: Sea urchin! 1/1- or β2/
When the value of L is about 0.4 or more, the residual stress value is 5 kp,
/ There is a very high possibility that it will be higher than vi.

That is, when considering the nozzle diaphragm C as the complex structure mentioned above, ρ+/l- and β2/1-
The upper limit value of β3/1 is 0.35 or less, so it is necessary to set the dimension 3 of the unwelded portion 18 of the nozzle plate 10 so that the value of β3/1 is 0.30 or more.

[Effects of the Invention] As described above, the nozzle diaphragm C of the present invention forms an unwelded part in the middle part of the nozzle plate and reduces the welding amount to an allowable value in terms of strength. It is possible to almost completely release the residual stress generated in the welded part, and it is possible to provide a nozzle diaphragm in which the reliability of the welded part is greatly improved.

In addition, the risk of friction between the nozzle diaphragm, which is a stationary part, and the blade, which is a rotating part, can be reduced and the operational reliability of the turbine can be greatly improved.
Wear.

[Brief explanation of the drawing]

Figure 1 is an external view of a conventional nozzle dianoram;
The figure is an external view of the nozzle plate installed in the first state shown in Fig. 1, Fig. 3 is a sectional view taken along line I[l-1#Q in Fig. 2, and Fig. 4 is a side view of Fig. 3. Fig. 5 shows a nozzle diaphragm of an embodiment of IJ A fe. Graph 1, Figure 8 shows the relationship between residual stress and primary Cree deformation 1. Graph 1, Figure 9
The figure is a graph showing the relationship between welding amount and residual stress. 10... Nozzle plate 11...
・・・・・・Inner support plate 12・・・・・・・・・・
...Outer support plate 15...Diaphragm inner ring 16...Diaphragm outer ring Patent attorney Suyama Buddha - Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Screw 1゜j'3/L Figure 7 Figure 6

Claims (2)

[Claims] (1) In a nozzle diaphragm formed by welding one of the plates holding the nozzle plate to the diaphragm outer ring and the other to the diaphragm inner ring by welding, the middle of the width of the nozzle plate in the +l+ /j direction of the diaphragm outer ring or inner ring A nozzle diaphragm characterized by having an unwelded part formed in the welded part. (2) The width of the unwelded part of the weld is 0.3 to 0.7 times the total width in the axial direction of the diaphragm outer ring or inner ring of the nozzle plate, Range 1
Nozzle dianolum as described in section.