JPS61192802A - Padding welding of blade tennon - Google Patents

Abstract

PURPOSE:To markedly improve the padding work performance by fitting a holding plate onto a tennon left at the top edge of the vane of a vane wheel of a steam turbine and applying the padding welding onto the residual tennon in the space between the penetration hole on the holding plate and the residual tennon. CONSTITUTION:A tennon (residual tennon) 12 having the nearly equal height (s) to the thickness of a shroud 13 is formed at the top part of a vane 3, and a holding plate 25 which consists of a copper plate having a penetration hole 26 which has the similar shape to that of the tennon 12 and into which the tennon 12 is fitted, keeping a prescribed interval between the tennon 12, and a cooling plate 30 for accelerating heat radiation are installed onto the vane 3. Then, the preparation for padding welding is performed, and in the space formed between the upper surface of the tennon 12 and the inside surface of the penetration hole 26, padding welding is performed on the residual tennon 12. With such method, the time for the achievement of the necessary padding amount 12'' can be shortened, and the padding part having high quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for welding a blade tenon of a steam turbine impeller or the like.

[Technical Background of the Invention] Generally, in a turbine impeller for a steam turbine or the like, a circumferential groove is formed in a single stage or in multiple stages in the radial direction on the outer periphery of a rotor disk. 1) are engaged to restrict movement in the radial direction.

FIG. 8 is an exploded partial view of the turbine impeller. On the outer periphery of the rotor circle ai, a plurality of grooves 2 extending on both front and rear surfaces are formed. The implanted portion 3' is fitted in a hollow shape, and the implanted portion 3'
A protrusion 4 formed on the opposing inner surface of the rotor disk 1 engages with the groove 2 of the rotor disk 1.

Incidentally, in the groove 2 forming portion of the rotor disk 1, one or more notches 5 are formed on the circumference, extending in the radial direction and having a width approximately equal to the thickness of the implanted portion 3'. After inserting the implanted part 3' of the blade 3 in the radial direction from the notch 5, slide it in the circumferential direction to remove the rotor disk 1.
By coupling to the outer periphery of the blade 3, movement of the blade 3 in the radial direction is restricted.

In this way, a predetermined number of blades 3 are pressed together in the circumferential direction and assembled into an annular body. In the final step, a stopper blade 7 having a groove 6 matching the shape of the notch 5 is engaged with the notch 5, as shown in FIG.

The FJI 6 of this stopper blade 7 and the notch 5 of the turbine disk 1
Unlike the case of the blade 3, the engagement is a simple fit, and the radial movement υ1 with respect to the rotor disk 1 is not performed, so the stop blade 7 is engaged as shown in FIG. 10 or 11. , the stop blade 7 and the adjacent blades 3a, 3
A pin hole 8 is provided in the thickness direction of the rotor disk 1 on the joint surface of the implanted portion of the blades 3C and 3d adjacent to the blade 3B, and a pin 9 is press-fitted into the hole 8. A bottle hole 10 is formed in the matching notch 5 and passes through the notch 5.
This is done by providing a pin 11 and press-fitting the pin 11 therein.

On the other hand, in FIG. 8, a protrusion (hereinafter referred to as a tenon) 12 is provided at the tip of the blade 3, which is integrally carved out from the blade 3, and a surrounding ring (hereinafter referred to as a shroud) is formed through the tenon 12. As shown in Fig. 10, the group of blades assembled into an annular body with the blades 13 pressed against each other is divided and fixed into several groups in the circumferential direction, and various excitation sources including steam power are used. It is made to be able to resist.

FIG. 12 is an enlarged view showing the joint part of the shroud 13 with the blade 3, and the tenon 12 is connected to the flat caulked part 12'.
The shroud 13 is fixed to the blade 3 by caulking until it becomes . The tenon 12 and the tenon caulking portion 12' resist steam force and high centrifugal force acting on the shroud 13.

The top of such a turbine impeller, more specifically,
When damage occurs to the shroud 13 or tenon 12.12', if the damage is severe, the blade is usually replaced with a new one, but if the damage is mild, the blade shoulder A technique called ``grinding'' has been adopted to reuse and restore damaged blades.

In the latter case, standard procedures may be used depending on the extent of the damage. First, if the damaged area is narrow and located close to the stop blade 7, then the group including the stop blade 7 is extracted from the group including the damaged blade and the damaged part is repaired.

To remove the blades, simply reverse the turbine impeller assembly procedure described above, but all blades are
As shown in FIG. 10, since the blades are arranged in groups, it is first necessary to separate all the blades to be extracted into individual blades.

For this purpose, the shroud 13 is usually cut using a grinder or the like as shown by the two-dot chain line in FIG. From the blades separated in this way, the stopper blade 7 shown in FIG. 10 is first removed, but for this purpose, the pin 9.11 is punched out. Once the stop blade 7 is removed, the remaining blades 3 (3a, 3b).

3C...) can be easily removed from the notch 5 by moving it stepwise in the circumferential direction along the groove 2 in FIG.

As shown in FIG. 14, the individual blades extracted in this way are obtained by first removing the tenon caulking portion 12' and extracting the shroud 13 using an appropriate tool, as shown in FIG.
Using a grinder or machining, a new tenon 14 is formed using a part of the effective part of the blade, as shown in FIG.

This is because the tenon 12' has been shaved off as described above, so when it is reassembled into the rotor disk 1 and the shrouds 13 are fitted and fixed, the tenon is to secure a caulking allowance corresponding to the tightening part 12'. . As a result, new feather 1
The height of the effective part of 5 is shortened by Δβ from the original height 1 to 12 (this is why the term "shoulder down" is usually used).

On the other hand, if the damage ranges over the entire circumference, it is necessary to lower the shoulders of all blades belonging to the pin impeller. In this case, it may be possible to separate the sound into individual sounds as described above, but it is better to remove the shroud and tenon by turning the entire circumference on a lathe. There are many.

That is, as shown in FIG. 16, first, the cutting line 1a.

The shroud 13 is scraped off from both sides along tb, leaving a tenon width. At this time, the shoulder sliding amount Δ in Fig. 15
It is also possible to cut the blade 3 deeply by an amount corresponding to β.

Next, by removing the Tenon caulked portion 12' along the cutting line (2), the remaining shroud 16 can be removed by a simple blow from the inner side as shown in FIGS. 17 and 18.

In this state, if the tops of the tenon 14 and blades 15 are finished using a grinder or the like as shown in FIG. 15, preparations for reassembly will be completed.

In this way, it is possible to repair only the top portion of the blade 3 without removing it. Of course, if manual work is done using a grinder or the like, the latter method of all-around repair can be applied to the former partial repair, and conversely, if it takes time and effort, the former method of separating into individual blades as described above can be applied. can also be applied to the latter all-around repair.

This shoulder-sliding technique is extremely effective for local repairs or as a temporary measure in emergencies, but as shown in Fig. 15, the originally required effective length of the blade 1 is removed by the shoulder-sliding amount Δ℃. Therefore, it is inevitable that the efficiency of the blade will decrease.

In particular, when this technique is applied all around the rotor impeller, its influence cannot be ignored, and when applied to multiple stages of a steam turbine, it can considerably worsen the steam turbine performance itself. Become. For example, when the above technique is applied to a 265 MV class intermediate pressure turbine of a thermal power turbine, there is a case where the heat consumption rate decreases by 0.04%.

In order to avoid such performance deterioration, avoid the above-mentioned shoulder-sharpening, that is, Tenon's scraping! 112'
It is necessary to compensate for this by some other method, and for example, as shown in FIG. 19, reshaping by Tenon overlay welding is also partially used.

The reason why this method is not generally carried out is that even if an appropriate welding rod is used and appropriate welding and heat treatment are performed, the remaining tenon 17 and the built-up portion 18 will be separated as shown in FIG. Since a heat affected zone 19 due to welding and macroscopic welding defects (hereinafter referred to as undercuts) are likely to occur at the welding start point 20a and end point 20b, it is necessary to withstand long-term high loads including vibration components. This is because the reliability of Tenon 12 is not sufficient.

[Object of the Invention] The present invention has been made in response to the above-mentioned conventional circumstances, and is capable of reliably repairing damage to the top of a blade, typically the shroud or tenon top of a steam turbine impeller, by reshaping the tenon using overlay welding. The present invention aims to provide a method of welding and overlaying vane tenons that can be repaired with high quality.

[Summary of the Invention] In other words, the present invention provides a weld build-up method for a vane tenon in which a weld build-up portion is formed on a residual tenon remaining at the tip of a blade. A backing plate having a through hole having a shape slightly more hole-shaped than the outer circumference is fitted, and the backing plate is fixed while maintaining the gap between the remaining tenon outer periphery and the inner surface of the through hole at a predetermined value, and then, A method for welding and overlaying a vane tenon, characterized in that welding is performed on the remaining tenon in a space formed by the upper surface of the remaining tenon and the inner surface of the through hole.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail using the drawings.

FIG. 3 is a diagram showing the top of the blade after monofilament processing to apply the present invention, and for the reasons mentioned above, in the present invention, the shoulder is not lowered, so the blade 3 has the initial effective part height. Sa β
Maintaining turtles. In addition, in order to minimize the area where the material quality changes due to welding, the amount of trimming of the tenon caulking part 12' when the blade is disassembled is minimized, and the height t of the built-up part 12'' is made as small as possible. Because of the need to
It will be around n.

FIG. 1 is a diagram showing the vane 3 shown in FIG. 3 in which a contact plate 25 made of a copper plate and a cooling plate 30 are attached to prepare for overlay welding of the first layer. As shown in FIG. 2, which is taken along arrow A-A in FIG. A hole 26 having the shape of is pre-drilled, and the backing plate 25 is fixed to the blade 3 by appropriate means so that the tenon 12 is centered in the hole 26.

The cooling plate 30 is made of a copper plate together with the contact plate 25, and is fitted onto the top of the blade 3 so that its upper surface is in contact with the contact plate 25.
It has a function to quickly dissipate the heat generated by welding and prevent the heat from reaching the base material of the blade 3.

In such a state, for example, the first layer is overlay welded using an appropriate welding rod made of a material with almost the same mechanical strength as Tenon and taking appropriate steps such as preheating. Experiments have shown that by setting the above-mentioned gap C1 to approximately 0.5n for blades in the size range used in large steam turbines, undercuts occurring at the welding start part 20a or the welding end part 20b can be minimized. It has been confirmed. After overlaying the first layer, it is necessary to take measures such as removing welding slag before overlaying the second layer.
It is important to cool the contact plate 25 sufficiently so that it does not sag due to heat.

In this embodiment, instead of this cooling procedure for the contact plate 25, a contact plate 25' (not shown) having the same shape as the contact plate 25 is used, and the applicable plate 25' is the two-direction plate shown in FIG. As shown in chain 826', the shape of tenon 12 has a hole 26 with an FIA C2 greater than C1.

In FIG. 1, if the above plate 25' is used instead of the plate 25, the plate 25, which is heated to a high temperature due to the plate 25 of the first layer, will not be cooled, and the plate 25 will be able to build up the second wI. It can be carried out. If overlaying of the third and subsequent layers is required, a plurality of contact plates 25' may be prepared.

By doing this, the required overlay 1 as shown in Figure 3
12". This also means that the age and number of temperature changes in the overlay area are minimized, resulting in high quality overlay. This makes it possible to obtain a certain amount.

The above-mentioned gap C2 may be determined based on the minimum total thickness required for reshaping the Tenon after overlaying and the welding workability for that purpose, and for C+ = 0.5 m, Cz = 1. O
n is appropriate.

Further, by suppressing C1 to 0.5n, the total dovetail of the 111th overlay portion 41 can be made smaller than the finished dimension 44, as shown in FIG. Therefore, even if an undercut occurs at the welding start point 20a or the welding end point 20b, the amount can be limited to an extremely small amount, and it can be effectively removed by lightly finishing the weld joint line 45 with a grinder in the final finishing stage. .

Before re-caulking the shroud 13, standard heat treatment such as annealing, inspection, etc. are required, but the details will be omitted.

FIG. 6 is a diagram for explaining another embodiment of the present invention, and as shown in FIG. 7, which is a view taken along arrow B-8 in FIG. A copper plate 31 with a hole 32 having a diameter is attached to the top of the blade. This copper plate 3
2 and the abutment plate 25 are fixed in advance with a suitable fastening member 33 such as a tapered pin, positioning the tenon-shaped hole 26 and the remaining tenon 12 becomes extremely easy.

Furthermore, since the copper plate 31 also has the role of the cooling plate 30,
Cooling during welding can be made even more effective. Note that it goes without saying that the cooling plate 30 may be fixed to the copper plate 31 in advance.

[Effect of the invention 1] As described above, according to the welding overlay method for vane tenons of the present invention, the workability can be greatly improved, and high quality rebuilt overlay tenons without undercuts can be produced. Obtainable. Therefore, the repair range by Tenon overlay welding can be expanded to a wider range. Thereby, it is possible to improve the operating rate of the steam turbine and maintain economic efficiency.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing preparations for overlay welding according to an embodiment of the method of the present invention, Fig. 2 is an explanatory diagram showing the A-A arrow direction in Fig. 1, and Fig. 3 is an explanatory diagram showing the preparation for overlay welding according to an embodiment of the method of the present invention. FIG. 4 is a partially enlarged view of FIG. 2, and FIG. 5 is an explanatory view showing the top of the blade after preparation for Tenon weld build-up, and FIG. FIG. 6 is an explanatory diagram showing another embodiment of the present invention. FIG. 7 is an explanatory diagram showing the direction of arrow B-8 in FIG. 6. FIG. 8 is an external view of the turbine impeller. 9
The figure is an external view of the stopper blade, Figure 10 is a front view showing the assembly of the blade, Figure 11 is a vertical cross-sectional view taken along line C-C in Figure 10,
Fig. 12 is a longitudinal sectional view showing the joint between the shroud and the blade, Fig. 13 is an explanatory drawing showing the method of cutting the shroud, and Fig. 1
Figure 4 is an explanatory diagram showing the state in which the tenon caulking part has been removed.
Fig. 15 is an explanatory diagram showing how to shoulder the blade, Fig. 16 is an explanatory diagram showing how to cut the tenon and shroud, and Fig. 1
7 and 18 are explanatory diagrams showing the state of the tenon and the shroud after cutting, and FIG. 19 is an explanatory diagram showing a conventional welding overlay method for the tenon. 1・・・・・・・・・・・・Rotor disk 3.15
・・・・・・Blade 5・・・・・・・・・・・・Notch 12.14・
・・・・・・Tenon 13・・・・・・・・・・・・Shroud 17・
・・・・・・・・・・・・Remaining Tenon 19・・・・
・・・・・・・・・Thermo type 1 part 20a・・・・・・・
・・・・・・・・・Welding start point 20b・・・・・・・・・
・・・・・・Welding end point 25・・・・・・・・・・・・
・・・Passing plate 26・・・・・・・・・・・・ Hole 30
.........Cooling plate 31...
・・・・・・・・・Copper plate 32・・・・・・・・・・・・
...... Hole 41 ...... Overlay part 45 ...... Welding joint line agent Patent attorney Sa Suyama - Figure 1 Figure 2 Figure 3 Figure 4 Figure 12 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17

Claims (3)

[Claims] (1) In a blade tenon weld build-up method in which a weld build-up part is formed on the residual tenon remaining at the tip of the blade, a through-hole having a shape slightly larger than the outer circumferential shape of the residual tenon is formed on the outer periphery of the residual tenon. and fixed the said plate while keeping the gap size between the outer circumference of the remaining Tenon and the inner surface of the through hole at a predetermined value, and then fixing the gap between the upper surface of the remaining Tenon and the inner surface of the through hole. A method for welding and overlaying a vane tenon, the method comprising welding overlay on the remaining tenon in the space to be formed. (2) The method of welding a vane tenon according to claim 1, wherein the backing plate is replaced every time one layer of welding is added. (3) Claim 2, in which the size of the through-hole in the backing plate used for welding overlay of the first layer is smaller than that of the through-hole of the backing plate used for welding overlay of the second and subsequent layers. The method of welding overlay of the vane tenon described.