JPS61138802A - Manufacturing method of diaphragm for steam turbine - Google Patents

Abstract

PURPOSE:To reduce thermal influence in a nozzle blade, by dividing a nozzle ring into two pieces, and a second nozzle ring is welded to a nozzle partition, then a first nozzle ring and the nozzle partition are tightly joined together. CONSTITUTION:A nozzle ring is divided into two pieces. A nozzle partition 12 disposing nozzle blades 16 in the circumferential direction is welded to the inside of a second nozzle ring 8 at the tip end side by means of electron beam welding. Next, a steam chest 6 and a first nozzle ring 7 as well as the nozzle partition 12 are all tightly joined together. With this constitution, thermal influence on these nozzle blades 16 during welding is reducible.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for manufacturing a diaphragm for a steam turbine, and in particular, to a method for manufacturing a diaphragm of a steam turbine, in particular, a nozzle blade is subjected to a surface hardening treatment. The present invention relates to a method for manufacturing a steam turbine tire, which is suitable for manufacturing a steam turbine tire with high precision and commercial quality.

[Background of the invention]

The first stage pressure control diaphragm 72 of the steam turbine is generally of the nozzle box type shown in FIGS. 6 and 47. This nozzle box type diaphragm is composed of a steam chest 1, a nozzle ring 2, and a nozzle partition 3. The nozzle partition 3Fi.

It is constructed by connecting several nozzles g4 at equal intervals in the circumferential direction, and is fixed within the nozzle ring 2 by welding 5. In addition, in Figure 6.

4' indicates the cross-sectional shape of the nozzle blade.

During turbine operation, the nozzle blade 4 has
In order to prevent erosion caused by solid particles in steam,
Publication No. 4-59507 and JP-A-55-164706
As shown in the publication, a method was adopted in which a surface hardening treatment was performed by performing a Cr--C treatment after gold boriding or carburization, and then welding to the nozzle ring 2.

However, the hardness of the surface hardened layer of the nozzle blade 4 that has been previously subjected to surface hardening treatment is as high as 1500 to 2oooi-t÷, so when the nozzle ring 2 and the nozzle partition 3 are in bath contact, the surface hardened layer has a negative effect, and even the nozzle! A4 is welded and deformed, and the hardened surface layer easily peels off.
There was a problem that the reliability of this hardened surface layer was reduced.

As a countermeasure for this, O
i, 6!1. A method of absorbing deformation of the nozzle 4 by providing a deformation prevention groove on the nozzle 4 outlet end side of the ring in a nozzle partition configured by connecting two nozzles 4;
As shown in Japanese Patent Application Laid-Open No. 58-186535, a method is adopted in which (after nozzle partitions t-a are created by connecting nozzles x' to each other, a boriding treatment is applied to the nozzle texture.

However, in the former case, there is a problem in that it takes a lot of time to machine the deformation-preventing grooves provided on the inner and outer rings. In addition, in the case of Kamaha, when welding the nozzle ring and nozzle part 7, there is still some peeling of the surface hardened layer due to deformation of the nozzle 4, which can avoid the adverse effect on the surface hardening layer. There is.

[Purpose of the invention]

The object of the present invention is to solve the problems of the prior art, and to provide a nozzle partition in which a nozzle ring and a nozzle blade, which has been subjected to a surface hardening treatment in advance, are connected to each other, so as not to adversely affect the surface hardened layer of the nozzle A/A. The purpose of the present invention is to provide and share a method for manufacturing a diaphragm for a steam turbine, which can be fixed by contacting with a bath, and can manufacture a diaphragm of high quality.

[Summary of the invention]

The first uninvented invention, as set forth in claim 1, includes a nozzle ring that includes a first nozzle ring portion on the steam chest side in the turbine axial direction, and a nozzle 2 on the tip side of the first nozzle ring portion. and the ring part, and inside this nozzle ring part of g2.

A mantissa number of nozzles gt-arranged at equal intervals in the circumferential direction and a nozzle partition / which has been subjected to a surface hardening treatment to each nozzle A are arranged, and the second nozzle ring portion and the nozzle partition 'f ! :The feature is that the steam chest, the first nozzle ring part, and the nozzle party ring part are connected by tm to the nozzle ring part of tlc2, which is fixed by electron beam welding. In addition, the surface hardening applied to the nozzle 4 in advance allows welding without any adverse effect on dK, thus making it possible to manufacture a diaphragm with high precision and high quality.

In addition, the second invention of the present invention is claim 5g4.
As described in Section 1, the nozzle ring is divided into a first nozzle ring part on the steam chest side in the turbine axial direction and a second nozzle ring part on the tip side of this, and inside this second nozzle ring part. In addition to arranging a plurality of nozzle blades at equal intervals in the circumferential direction and arranging a nozzle partition in which each nozzle blade is subjected to a surface hardening treatment,
The nozzle part 7 is positioned within the nozzle ring part of the Yon T-42, and the second nozzle ring part and the nozzle partition are brought into contact with each other by T-Seiko beam welding, and then the front 6 steam chest and the first nozzle are connected. The feature is that the ring part is connected in tg contact with the #G20 nozzle ring part to which the nozzle partition is fixed, and with this configuration, it is possible to manufacture a diaphragm with even higher abrasion and higher quality. .

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of a method for manufacturing a diaphragm according to the present invention.

In the method of the present invention, as shown in FIG. 1 before assembly.

It is divided into a steam chest 6, a nozzle ring, and a nozzle partition 12.

The nozzle ring has a first section on a dividing surface in the turbine axial direction.
It is divided into 42 nozzle ring parts 7.8, and the broom 1
The nozzle ring part 7 of is connected to said steam chest 6, and the second nozzle ring part 8 is adapted to be connected to said first nozzle ring part 7.

In the present invention, the reason why the nozzle rings TGT and GZ are divided into nozzle ring parts 7 and 8 is to weld the nozzle partition 12 inside the nozzle ring by Seiko beam welding, as will be described later. This is because the range is narrow.

A positioning plate 9 is integrally attached to the tip of the second nozzle ring portion 8, and a groove 10.11 for positioning the nozzle partition 12 is formed in the positioning plate 9. 2. The positioning plate 9 is removed after the nozzle partition 12fr is welded by electron beam fd contact.

The nozzle partition 712ri is constructed by connecting a plurality of arc-shaped four nozzle units 13 in a half/rig shape. The nozzle blade unit 13 has an arc shape, and
It is constructed by connecting fJ1a nozzles 9X16 at equal intervals between the outer ring pieces 14 and 15. Nozzle blade 1
6 is formed of 130r*. The hardness of the coating surface hardening layer of the nozzle blade 16 is , since the hardness of solid particles in steam is 500 Hv.

It is set to be about 1500 to 2000 Hv which is harder than this. Thereby, corrosion resistance can be imparted to the steam passage surface of the nozzle blade 16. After subjecting the nozzle blade 16 to surface hardening treatment, the four nozzle blade units 13 are hardened at the grooved portion.
contact,#? ') They are connected in a 7-g shape, and the d-contact part is indicated by the reference numeral 17.

As mentioned above, the nozzle No. 16 having a single mantissa is connected between the inner and outer ring pieces 14 and 15 to form the nozzle blade unit 13'rt.
The reason why the multiple nozzle blade units 13 are formed into a semi-ring shape and then assembled into a ring-shaped nozzle partition/12 is to reduce the number of welded parts when manufacturing the nozzle partition 12. This is done in order to reduce welding deformation and to minimize the influence on the hardened surface layer applied to the nozzle No. 16 during welding.

Next, as shown in FIG. 4, the half-ring-shaped part and the nozzle part 7 12 combined in a ring-shape are arranged in the second nozzle ring part 8, and the positioning plate 9 is formed on the positioning plate 9. The nozzle sensing unit 1 constituting the nozzle partition 12 is placed in the groove 10.11 for
3, fit and position the ring formed by the outer/glue 14 and 15, and position the nozzle part 7 yong 1 during welding.
2 retains its shape so that it does not deform.

Next, the second nozzle ring part 8 and the nozzle part 7 yon 12 are welded together by electron beam welding from the inlet end of the nozzle 160 to the outlet end, as shown by arrow a in FIG. do. The welded portion of the second nozzle ring portion 8 and the seven nozzle partition 12, which are welded by electron beam welding, is indicated by reference numeral 18. The electron beam welding does not require a welding groove angle, and since the melting range is narrow, the heating range is also small. Therefore, the negative effect f# during welding due to surface hardening of the nozzle blade 16 is significantly reduced. Moreover, since this electron beam welding is performed in a vacuum, there is no influence of hydrogen, and ffj-tangential cracking of the nozzle partition 12 can be completely eliminated.

Furthermore, as mentioned above, by welding the second nozzle ring portion 8 and the nozzle partition 12 from the nozzle fi 160 end side toward the outlet end side, the outlet of the nozzle blade 16 has a thin wall thickness. Since the end portion is gradually heated by the welding heat when the four-wire beam is connected, thermal stress can be reduced, and peeling of the hardened surface layer around the exit end portion due to thermal deformation can be reliably prevented. can. Moreover, the nozzle partition 12' is located! @to, t for deciding
Since the nozzle partition 12 is positioned through the hole 2, deformation of the nozzle partition 12 with respect to the nozzle ring portion 8 of the metal 2 can be prevented.

After welding the second nozzle ring portion 8 and the nozzle part 7 yon 12 by Seiko beam welding, the end of the second nozzle ring portion 8 to be welded to the 5g1 nozzle ring portion 7 is welded to the finishing line 20. Mechanical power loe and
The end portion where the positioning plate 9 is provided is machined to the position of the finishing line 21, and the positioning plate 9 is removed. Due to this machining.

In addition to the unnecessary positioning plate 9, it is also possible to remove spike defects 19't that occur at the tip of the melt in electron beam welding.

After machining the second nozzle ring part 8 to which the nozzle partition 12 is fixed, the first nozzle ring part 7 and the second nozzle ring part 8 and the steam chest 6 and the first nozzle ring part 7 are assembled. and are respectively welded by normal welding to obtain a diaphragm gold as a product. In addition, 2 in FIG. 5 and 1. The Mg2 portion of the second nozzle ring portion 7°8 is indicated by the symbol 22, and the welded portion between the steam chest 6 and the first nozzle ring portion 7 is indicated by the symbol 23.
Indicated by Further, in 1 tJ , FIGS. 3, 4, and 5, 16' indicates the cross-sectional shape of the nozzle.

The method of constructing the diaphragm of the embodiment described above has a similar effect.

■ A plurality of nozzle rods 16 are connected at equal intervals between the inner and outer/glue pieces 14 and 15 to form a nozzle 4 unit 13, and the nozzle No. 16 is subjected to surface hardening treatment to form a plurality of nozzle rods 16.
Nozzle Beninit 13? Spring contact is made in the shape of a half ring, and the nozzle partition 1 is created by combining the half ring shapes.
2i configuration, there are fewer welded parts to form the nozzle partition 12't 11th, thereby reducing welding deformation of the nozzle 16th, and nozzle b
In addition to being able to eliminate the shadow*1 on the hardened surface layer of 116, it is also possible to improve work efficiency. A groove 10 for positioning is attached to this. Form these grooves 10. Since the seven nozzle partitions 12 are positioned within the second nozzle ring portion 8 via the nozzle ring portion ll' and then welded by electron beam welding, the nozzle partitions relative to the second nozzle ring portion 8 during welding are 12 thermal deformation can be prevented, and therefore welding can be performed with high precision.

■ By dividing the nozzle ring into first and second nozzle ring parts 7.8 at the dividing plane in the turbine axial direction,
For welding the nozzle ring and nozzle partition 12,
Enables the adoption of electron beam welding with a narrow melting range, making it possible to
Nozzle ring part 8 and nozzle partition 1:l:
f! :'! By iE child wide beam welding,
As a result of narrowing the heating range, it is possible to significantly reduce the amount of heat applied to the nozzle blade 16 subjected to surface hardening treatment, and since electron beam welding is performed in a vacuum,
Since there is no influence of hydrogen, joint cracking of the nozzle g16 can be completely eliminated, and a high quality diaphragm kg can be manufactured.

■ When welding the second nozzle ring portion 8 and the nozzle partition 12 by electron beam welding, the nozzle blades 16
Since welding is performed from the artificial end side to the outlet end side, the thermal stress at the thin outlet end of the nozzle 16 during welding can be reduced, and the nozzle blade 16 due to thermal deformation can be reduced. The surface around the exit end (hardened layer can be prevented from peeling off).

■ When removing the positioning plate 9 attached to the second nozzle ring portion 8 by machining, the spike defect 19 that occurs at the welding tip of electron beam bath welding can be removed at the same time. Quality problems associated with spike defects can be eliminated.

〔Effect of the invention〕

According to the first aspect of the present invention described above, the nozzle ring is divided into the first nozzle ring portion on the steam chest side in the turbine axial direction and the second nozzle ring portion on the tip thereof (on the Sfl side). , a nozzle partition in which a plurality of nozzle blades are arranged at equal intervals in the circumferential direction and a surface hardening treatment is applied to each nozzle A is arranged in this second nozzle ring portion, and the second nozzle The ring part and nozzle partition are welded together using electron beam welding.

Then, the steam chest, the first nozzle ring part, and the second nozzle ring part to which the nozzle partition is fixed are connected by welding, and a nozzle ring is formed.
The nozzle partition connected to the nozzle L%, which has undergone surface hardening treatment in advance, can be in contact with the nozzle L% after the electron beam bath, and the nozzle ring, nozzle partition, and gold have a narrow heating range and have little negative effect on the nozzle blade. Since welding is carried out using the electron beam welding method, which eliminates the risk of weld cracking due to the influence of water stains, it is possible to manufacture high-precision, high-quality diaphragms. According to the invention, after the nozzle part 7 is entirely positioned within the second nozzle ring part, both members are welded by electron beam welding, t'<tt, during welding. Since thermal deformation of the nozzle partition relative to the second nozzle ring portion can be suppressed, it is possible to produce a diaphragm t-d with even higher stiffness.

[Brief explanation of drawings]

1 to 5 show an embodiment of the method of the present invention,
Figure 1 is a perspective view of each member before assembly, Figure 2 is a plan view of a part of the nozzle partition, Figure 3 is an enlarged sectional view of the nozzle partition, and Figure 4 is the second nozzle ring part and the nozzle partition. An enlarged sectional view of the assembled state,
Figure 45 is a perspective view of a part of the nine diaphragm assembled with each member. Figure 6 is a perspective view showing an example of mineral technology, and Figure 47 is a plan view of the same nozzle partition. 6... Steam chest, 7.8... No. 1.42 nozzle ring part, 9... Positioning plate, 10.11.
...Groove for positioning, 12...Nozzle partition, 13...42-knit nozzle composed of inner and outer ring pieces and multiple nozzle blades, 14.15...Inner, remove/group Piece, 16... Nozzle, d, is... J2 nozzle ring part and nozzle party, welded part of John. 20.21... Finished edge by machining of the second nozzle ring part, 22... Welded part of the gl, m2 nozzle ring part, 23... Welded part of the steam chested first nozzle ring part , a... Welding direction during electron beam welding.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a diaphragm for a steam turbine comprising a steam chest, a nozzle ring, and a nozzle partition, in which the nozzle ring is connected to a first nozzle on the steam chest side in the axial direction of the turbine. ring part and
This is divided into a second nozzle ring part on the tip side,
Within this second nozzle ring portion, a nozzle partition in which several nozzle blades are arranged at equal intervals in the circumferential direction and each nozzle blade is subjected to a surface hardening treatment is arranged, and the second nozzle ring and the nozzle partition are welded by electron beam welding, and then the steam chest, the first nozzle ring part, and the second nozzle ring part to which the nozzle partition is fixed are welded and connected. A method of manufacturing a diaphragm for a steam turbine. 2. In claim 1, the nozzle partition has a plurality of nozzle blades attached at equal intervals between arc-shaped inner and outer ring pieces to form a nozzle blade unit, and the nozzle blade unit A method for manufacturing a diaphragm for a steam turbine, characterized in that the diaphragm is surface hardened and a plurality of the nozzle blade units are welded into a circular shape. 3. In claim 1, the second nozzle ring portion and the nozzle partition are welded by electron beam welding from the nozzle blade inlet end side to the nozzle blade outlet end side. A method of manufacturing a diaphragm for a steam turbine. 4. A method for manufacturing a diaphragm for a steam turbine comprising a steam chest, a nozzle ring, and a nozzle partition, wherein the nozzle ring is a first nozzle ring portion on the steam chest side in the turbine axial direction;
This is divided into a second nozzle ring part on the tip side,
Inside this second nozzle ring part, a nozzle partition is arranged in which a plurality of nozzle blades are arranged at equal intervals in the circumferential direction and each nozzle blade is subjected to a surface hardening treatment, and the nozzle partition is the second nozzle ring part and the nozzle partition by electron beam welding;
A method for manufacturing a diaphragm for a steam turbine, characterized in that the steam chest, the first nozzle ring portion, and the second nozzle ring portion to which the nozzle partition is fixed are connected by welding. 5. In claim 4, the nozzle partition has a plurality of nozzle blades attached at equal intervals between arc-shaped inner and outer ring pieces to form a nozzle blade unit, and the nozzle blade unit A method for manufacturing a diaphragm for a steam turbine, characterized in that the diaphragm is surface hardened and a plurality of the nozzle blade units are welded into a circular shape. 6. Claim 4, characterized in that the second nozzle ring portion and the nozzle partition are welded by electron beam welding from the nozzle blade inlet end side to the nozzle blade outlet end side. A method of manufacturing a diaphragm for a steam turbine. 7. In claim 4, a positioning plate is integrally attached to the second nozzle ring portion, a positioning groove is formed in the positioning plate, and the nozzle partition is positioned through the groove. At the same time, the second
A method for manufacturing a diaphragm for a steam turbine, the method comprising: welding a nozzle ring portion and a nozzle partition together, and then cutting off the positioning plate.