JPS60116874A - Runner for use in hydraulic machine - Google Patents

Abstract

PURPOSE:To increase the strength of a runner used in a hydraulic machine, by forming rib plates on the surfaces of a runner crown and a runner band to extend in the radial and circumferential directions, and selecting the thickness of the radial rib plates and that of the circumferential rib plates to take particular different ratios respectively to the thickness of a cover plate. CONSTITUTION:A runner is composed of a runner crown 2a, a runner band 2b and a plurality of runner blades 2c held between the runner crown 2a and the runner band 2b. A plurality of rib plates 3 are arranged on the surfaces of the runner crown 2a and the runner band 2b to extend in the radial and circumferential directions, in the manner of forming a grid-like structure, and the opening of each grid is covered by a cover plate 4. Here, providing that the thickness of the cover plates 4 is T, the thickness tR of the radial rib plates is selected to satisfy the following relationship, tR>=(2T)<1/2>, and the thickness tC of the circumferential rib plates is selected to satisfy the following relationship, tc>=T.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a runner for hydraulic machinery, and particularly to a runner for a hydraulic machine.
→ SO J-77'1 Rikishi ^ 1 non, P Boo, J -71+ M = 1s X: l/P r, t
：1#nRelates to a hydraulic machine in which the opening of the cover plate is covered with a cover plate.

[Technical background of the invention]

In general, large 7-lancine water turbine runners are made so that the runner can be divided into an initial number of runner pieces due to production reasons or transportation requirements. It is often transported to and assembled.

In this case, a flange is formed at the joint of each launch piece, and during assembly, the flange joint surfaces of the runner pieces are butted against each other, and the flange parts are bolted together. When the flange is connected in this way, the flange protrudes from the surface of the launch crown or runner band, so when the runner rotates, the protruding flange agitates the water.
There was a problem that the frictional resistance of water increased and hydraulic efficiency decreased.

Therefore, in order to reduce the resistance caused by the protruding flange, the flange joint of the runner was covered with a cover plate.
The runner is designed so that there are no partial protrusions around the entire circumference. Figures 1 and 2 show the launch of this type of hydraulic machine, and the runner 1 consists of a runner crown 2a, a runner band 2b, and a plurality of runner blades 2C held between them. ing. Among these, a plurality of groove plates 8 are provided on the upper surface of the runner crown 2a.
are welded and connected in a grid pattern in the radial and circumferential directions. Each of the openings in the area surrounded by these rib plates 8 is covered by a cover plate 4, and the entire periphery of these cover plates 4 is welded together along the weld line indicated by reference numeral 6 in FIG. has been done. By covering the flange joint portion of the split runner with the rib plate 3 and cover plate 4 in this way, the underwater frictional resistance of the runner during rotation can be reduced.

Similarly, the rib plate 8 is also placed on the side of the lunch band 2b.
, 3 are welded together, the cover plate 4 is attached, and the shielding portion is welded together. Note that a balance hole 6 is bored in the cover plate 4 in order to reduce the pressure difference acting on the inner and outer surfaces.

[Problems with background technology]

When the runner 2 configured as described above rotates at high speed in water, high-frequency pulsating water pressure acts on the surface of the cover plate 4, so that the cover plate 4 is affected as shown in FIGS. 8 and 4. High frequency bending moments MA and MB are generated. In particular, the bending moments J and MB generated in the vicinity of the center of the welded sides at both ends of the cover plate 4 are larger than the moments generated in other parts of the cover plate. Therefore, the cover plate 4 given by the quintic equation
The repeated stresses σ8 and σB generated in the vicinity of the center of the welding sides at both ends of the inner surface of each of the inner surfaces of the cover plate v-) also have larger values compared to other parts of the cover plate v-).

Here, σ is the bending stress, MU bending moment, 2 is the section modulus of the plate with respect to bending deformation, and h is the plate thickness. It is known that as a result of high repeated stress occurring in the welded joint of the cover plate 4, fatigue cracks are likely to occur, and once cracks occur, they propagate rapidly.

For this reason, conventional measures have been taken to prevent such risks by increasing the thickness of the cover plate 4 to reduce the bending stress.

By the way, conventionally, as mentioned above, efforts have been made to improve the fatigue strength of the cover plate by focusing only on the bending stress generated by the cover plate. This is based on the assumption that the deformation mode of the plate 4 is symmetrical, that is, in phase, across the radial slope plate 8.

, the bending moment of the radial rib plate 8) M
c is close to zero, and a bending moment MD approximately equal to one deflection moment MB acting on the cover plate is generated in the circumferential rib plate 8. Generally, as shown in FIG. 6, the plate thickness t of the plate 8 of the cover plate 4 is approximately in the range of 20 mm to 40 mm, and in many cases they are approximately equal, but T=+o ++ + == ')E −
+-()"+ F et vI+ 7' plate σ) M 1
1; E T %E Since the thickness of the cover plate may be approximately 20 to 80% greater, from equations (1) and (z), the stress generated at the welded joint of the rib plate 8 can be calculated as follows:
- less than the stress generated in the welded joint of the plate 4;

Therefore, for the in-phase deformation mode of the adjacent cover plate v-), the stress generated in the cover plate can also be suppressed to below the fatigue strength of the plate material as described above.

On the other hand, recently, various studies have shown that the deformation mode of the force and the plate is not only the in-phase mode as mentioned above, but also the number of plates and the number of plates (see Fig. 7) depending on the position and number of lance holes. As shown in FIG. A bending moment MD approximately equal to the bending moment ()MB acting on the cover plate is generated, whereas the bending moment (MD) acting on the cover plate 8 is approximately equal to the bending moment (MA) acting on the cover plate.
A bending moment approximately twice as large as the Therefore, the bending stress σC2σD generated in the welded joint of the rib plate 8 due to these bending moments) MQ and MD is calculated as follows: As in the conventional case, the thickness t of the rib plate 8 is equal to the thickness t of the cover plate 4. If so, from equations (1) and (2), especially in the radial rib plate, a high bending stress of approximately twice the bending stress σ generated in the cover plate V-)4 to striking σO-2σA occurs. become. Dad, the thickness t of the rib plate is the same as the thickness T of the cover plate like in the past! Even if it is increased by 80%, the bending stress σC generated in the radial rib plate will still be about 1.2 times as high as the bending stress σ generated in the cover plate 4, according to equations (1) and (2).

In this way, for the opposite phase deformation mode of adjacent cover plates, even if we focus on the stress generated in the cover plate as in the past and conduct a stiffness design so that the stress is less than the fatigue strength of the plate material. As a result of the fact that approximately 1.2 to 2.0 times as much stress is generated in the rib plate as in the cover plate, this stress exceeds the fatigue stress of the plate material, causing fatigue cracks and the cover plate v-) There was a problem in that it could lead to damage.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a runner for a hydraulic machine which has sufficient strength even when adjacent cover plates vibrate in opposite phase deformation modes, by solving the problems of the conventional runners described above.

[Summary of the invention]

In order to achieve the above object, the runner for a hydraulic machine according to the present invention has a plurality of rib plates protruding from the surfaces of the launch crown and the runner band by welding, and each opening surrounded by the rib plates is covered with a cover plate. In a runner for a hydraulic machine in which the joint part between the cover plate and the cover plate is welded, the plate thickness of the radial lip v-1 is at least %/2 times that of the cover plate,
The plate thickness of the local direction rib plate is greater than or equal to the plate thickness of the cover plate.

[Examples of disasters caused by inventions]

An embodiment of a hydraulic machine launch according to the present invention will be described with reference to FIGS. 8 and 9.

The structure of the hydraulic machine launch according to the present invention is similar to the conventional one, and is composed of a runner crown 2a, a runner band 2b, and a plurality of runner blades 2C held between them.

A plurality of overlapping plates 8 are arranged on the surfaces of the launch crown 2ab and the runner band 2b in the radial and circumferential directions so as to form a lattice. These rib plates 8 may be welded to the runner crown 2a and the runner band 2b, or may be formed integrally from the beginning by casting.

Further, each of the openings corresponding to the grid surrounded by the rib plate 8 is closed by the cover plate 4, and the entire circumference of the cover plate 4 is covered by the rib plate 8.
It is welded to the

According to the present invention, the thickness f of the cover plate 4 is
When T, the plate thickness tR of the radial rib v-)3>
It is constructed so that v'2 T, and is printed so that ->T.

Next, the plate J of the radial and circumferential extending plate 8 is based on the thickness of the cover plate 4! The basis for determining ftR+tc as described above will be explained.

FIG. 9 shows the magnitude of the bending moment MC acting on the radial direction glide plate 8. Coverp V
-) When the 4 deformation modes are symmetrical, that is, in phase, across the radial slope plate 8, the bending moment MC acting on the radial slope plate 8 becomes almost zero, as shown by the solid line in the figure. Further, in the vicinity of the welded portion between the circumferential rib plate 8 and the cup plate 4, a bending moment MD approximately equal to that of the cover plate 4 acts on the circumferential rib plate 8. Therefore, at the welded joint between the cup (-V-) 4 and the rib plate 8, the thickness of the rib plate 8 is thicker than that of the cover plate 4, and the bending moment acting on it is also smaller, so that it is generated on the surface of the rib plate 8. The bending stress σC1σrJ generated on the surface of the cover plate 4 is equal to or equal to the bending stress σ8, σB generated on the surface of the cover plate 4.
The value is below

On the other hand, as shown in FIG. 7, when the deformation mode of the cover plate 4 is asymmetrical hitting opposite phase by sandwiching the radial slope plate 3, the deformation mode of the cover plate 4 is in the same phase as the in-phase mode on the circumferential slope plate 8. A bending moment MB that is approximately equal to the bending moment (bending moment) MB that acts on the cover plate 4 acts on the radial slope plate 3, but a bending moment MQ that is approximately twice as large as the bending moment MA that occurs on the cover plate 4 acts on the radial slope plate 3.

In FIG. 10, as shown in FIG. 6, the thickness of the cover plate 4 is T, the thickness of the radial slope plate 8 is tR, and tR=, / Correspondence of the ratio σC/σA of the bending stress generated on the surface of each plate given an arbitrary value of the ratio Mc/MA of the bending moment acting on each of the radial sliding plate 8 and the cover plate 4 in the case of a needle. This shows the relationship. As is clear from this figure, as % Mc/MA increases, σC
/σA also increases, but when MQ=2MA, σC matches σA.

In addition, FIG. 11 shows the thickness tH of the plate when the radial slope plate 8 receives a bending moment Mc twice that of the cover plate 4, based on the equation (1) (21).
The figure shows the relationship between the surface bending stress σC and the surface bending stress σC.

In addition, if the plate thickness tR of the radial direction plate (brake) 8 is the same as the plate thickness T of the cover plate 4 as in the conventional case, or J-t
Since the thickness becomes 1jtH (v2T) when the thickness is increased by 2 to 80%, the bending stress σC becomes a high value exceeding the bending stress σA generated on the surface of the force 1 per plate 4, as is clear from FIG.

Next, the plate 'Bta of the circumferential groove plate 8 will be considered. When the deformation mode of the cap V-14 is in the opposite phase, a bending moment MD that is approximately equal to the bending moment IA acting on the cap V-14 acts on the circumferential groove plate 8. However, if the cover foot 4 of the plate Wtce of the circumferential glide plate 3 is made more than 7, the bending stress σ generated on the surface of the circumferential glide plate 3 is
D is equal to or greater than the stress σB generated on the surface of the cover plate 4.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the thickness of the cover plate is TK, the thickness of the rib plate in the radial direction is tRftR〉%/TT, and the thickness of the rib plate in the circumferential direction is Since t O>T, even if the deformation mode of the cover plate is in the opposite phase and a bending moment approximately twice as large as the bending moment acting on the cover plate acts on the radial slope plate, the radial slope plate The bending stress generated on the surface of the cover plate can be made equal to or one degree lower than the bending stress generated on the surface of the cover plate. In fact, the bending stress generated on the surface of the rib v-) in the same direction can be suppressed to the same level or less than the bending stress generated on the surface of the cover v-). therefore,
Hydraulic machinery with sufficient strength against fatigue waves ++1 caused by high-frequency water pressure pulsations.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a part of the runner of a hydraulic machine with a cover plate, Figure 2 is a plan view of the same runner, and Figure 8
The figure is a cross-sectional view taken along the III-In line in Figure 2.
The figure is a cross-sectional view along the ■-■ line in Figure 2, and Figure 5 is an explanatory diagram showing the in-phase deformation mode of the cover plate. Figure 6 is an enlarged cross-sectional view of the welded part of the beam plate and cover plate, Figure 7 is an explanatory diagram showing the opposite phase deformation mode of the cover plate, and Figure 8 is the cover plate and radiation of the runner according to the present invention. FIG. 9 is a cross-sectional view showing the vicinity of the welded part of the radial direction glide plate, FIG. M4 and ml
Figure 11 is a diagram showing the relationship between the bending stress ratio σC/σA, and Figure 11 is a diagram showing the relationship between the plate thickness tR of the radial slope plate and the bending stress σC generated on the surface of the rib v-). be. l...Runner, 2a...Runner crown, 2b...
・Plate, 4...Cover plate. Applicant's agent Inomata Kiyoshi 1st bacterium 2nd 3rd ugliness 1st bacterium

Claims (1)

[Claims] A radial glide plate and a circumferential glide plate are provided in a grid pattern on the surface of the launch crown and runner band, each opening surrounded by the rib plate is covered with a cover plate, and the cover plate is connected to the rib plate. In the launch of a hydraulic machine in which parts are welded together; the thickness of the radial glide plate is at least five times the thickness of the cover plate, while the thickness of the circumferential glide plate is the same as the thickness of the cover plate. IF the above is true! jW
Water Kai, the runner of the Yumai.