JP3592664B2 - Method for manufacturing turbine casing - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a turbine casing having a cooling hole in an outer peripheral portion, and more particularly to a method for manufacturing a cast turbine casing.
[0002]
[Prior art]
FIG. 7 is a cross-sectional view showing a part of the gas turbine, wherein 1a and 1b are moving blades, and 2a and 2b are stationary blades. The stationary blades 2a and 2b are supported by a turbine casing 3. Since the turbine casing 3 is warmed by the high-temperature and high-pressure combustion gas GAS flowing through the passage portion 4, the turbine casing 3 is made of a material having sufficient strength to withstand the environment of the high-temperature and high-pressure combustion gas GAS. Is required.
[0003]
When made of a material having a low high-temperature strength, such as a cast iron turbine casing, a large number of cooling holes 5 extending in the axial direction are provided in the outer peripheral portion to cool the whole.
[0004]
Further, even when the turbine casing is made of a material having high-temperature strength, such as a turbine casing made of cast steel or the like, cooling for cooling the entire turbine casing from a difference in radial thermal expansion with the adjacent exhaust casing 7. Holes may be required.
[0005]
By the way, when the turbine casing 3 is formed of a material having a good flow of molten metal such as a molten metal for cast iron, a method of manufacturing the cooling holes 3 with cast holes 5 'as shown in FIG. The most common. However, in the case of molten metal for cast steel, since the flow of molten metal is poor, it may be very difficult to manufacture the cooling hole 3 with the cast hole 5 ′.
[0006]
[Problems to be solved by the invention]
When it is not possible to produce a cooling hole by using a cast hole as in the case of the cast steel turbine casing described above, it is usual to perform machining using a drill such as an end mill. However, drilling holes by mechanical processing, such as small diameter cooling holes, long axial lengths, angles to the horizontal direction, or complicated shapes such as taper, take a considerable amount of time. Costly.
[0007]
The present invention has been made in view of such conventional circumstances, and even when casting a turbine casing with a molten metal in which the flow of molten metal is poor and the production of a cooling hole by a cast hole is difficult, the cooling hole is easily formed. It is an object of the present invention to obtain a method of manufacturing a turbine casing that can be used.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is a method for manufacturing a cast turbine casing having a plurality of cooling holes in an outer peripheral portion, wherein a plurality of axial directions are provided on an outer peripheral portion of the turbine casing after casting. The molten metal is cast into a mold formed so as to form a groove extending into the mold, and after solidification of the molten metal, a turbine casing, which is a casting, is taken out of the mold and formed on the outer peripheral portion of the cast turbine casing. The groove is covered with a lid, and the lid and the outer periphery of the turbine casing are welded to form a cooling hole.
[0009]
According to a second aspect of the present invention, in the method for manufacturing a cast turbine casing having a plurality of cooling holes on an outer peripheral portion, a plurality of axially extending grooves and a plurality of circumferentially extending grooves are formed on the outer peripheral portion of the cast turbine casing. The molten metal is cast into a mold formed to form a flange portion in the direction, and after solidification of the molten metal, a turbine casing, which is a casting, is taken out of the mold, and the groove formed in the turbine casing after the casting is formed. Is covered with a lid, the lid is welded to the outer periphery of the turbine casing, and a hole is formed in the flange by machining to form a cooling hole.
[0010]
Further, the invention according to claim 3 is characterized in that a plurality of the grooves are covered with a single lid, and the lid and an outer peripheral portion of the turbine casing are welded.
Still further, the invention according to claim 4 is that a step is formed at an edge of the groove, a groove to be fitted with the step is formed in the lid, and a periphery of the lid is welded to a turbine casing. Features.
[0011]
According to these inventions, at the time of casting of the gas turbine casing, a groove for the cooling hole is manufactured in advance, and then the cooling hole is fixed to the groove by covering the groove with a separately manufactured lid and by welding. It can be formed to the end. This makes it possible to easily form cooling holes in a turbine casing made of cast steel or the like having a complicated shape that is difficult to machine with a drill.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a method for manufacturing a turbine casing according to the present invention will be described with reference to the drawings.
(First Embodiment)
FIGS. 1, 2 and 3 are diagrams showing a first embodiment of the present invention. FIG. 1 is a perspective view showing a part of a process of manufacturing a turbine casing, FIG. 2 is a perspective view showing a part of a state of a turbine casing after casting removed from a mold, and FIG. 3 is a cover for covering a groove. It is a perspective view of.
[0013]
In FIG. 1, a plurality of grooves 8 extending in the axial direction except for the flange portion 6 are formed on the outer periphery of the cast turbine casing 2 at predetermined intervals in a circumferential direction. This shows a state in which each is covered with one lid 9 and the turbine casing 3 and the lid 9 are welded and fixed by laser welding between adjacent grooves 8. Reference numeral 10 denotes a laser weld, 11 denotes a hole formed in the flange 6, and 12 denotes a hole drill such as an end mill.
[0014]
Hereinafter, a method for manufacturing a turbine casing according to the present invention will be described.
FIG. 2 shows the turbine casing 3 after casting. This turbine casing 3 is manufactured as follows. First, a mold (not shown) is formed so that a plurality of grooves 8 extending in the axial direction are formed in the outer peripheral portion of the turbine casing after casting, and a molten metal such as cast steel is cast into the mold.
[0015]
Next, after solidification of the molten metal, the turbine casing, which is a casting, is taken out. FIG. 2 shows the state after the removal.
Next, as shown in FIG. 1, three of the plurality of grooves 8 are collectively covered with one separately manufactured lid 9, and the turbine casing 3 and the lid 9 are interposed between adjacent grooves. And fix it by laser welding.
[0016]
Finally, in order to make a hole 11 communicating with the cooling hole 5 in the flange portion 6, machining is performed by a drill 12 such as an end mill from the downstream side of the flange portion 6. The cooling hole is completed by connecting the hole 11 to the cooling hole 5.
[0017]
As described above, according to the method for manufacturing a turbine casing of the present invention, in the casting process, an axial groove is formed in advance on the outer periphery of the turbine casing, and the cooling hole is formed by covering the groove with a lid. Even when the turbine casing is cast from a molten metal for cast steel in which the flow of the molten metal is poor and it is difficult to form the cooling holes by the cast holes, the cooling holes can be easily formed.
[0018]
(Second embodiment)
FIGS. 4, 5, and 6 are views showing a second embodiment of the present invention. 4 is a perspective view showing a part of a process of manufacturing the turbine casing, FIG. 5 is a perspective view showing a part of the turbine casing taken out of a mold, and FIG. 6 is a perspective view of a lid covering a groove. is there.
[0019]
In the present embodiment, a mold is formed so that a step 8a is formed at the edge of the groove 8, and a groove 13 is formed in the lid 9 so as to match the groove 8 with the step 8a. After fitting the groove 9 into the groove 8, the periphery of the lid 9 is welded by TIG welding or the like. Reference numeral 14 denotes a TIG weld. The other points are the same as those in the first embodiment, and thus the description is omitted.
[0020]
According to the present embodiment, the groove 13 of the lid 9 is fitted into the step 8a provided at the edge of the groove 8, so that the positioning of the lid 9 can be performed accurately and the periphery of the lid 9 is welded by TIG welding or the like. By doing so, the weldability between the turbine casing 3 and the lid 9 can be further enhanced.
[0021]
【The invention's effect】
As described above, according to the present invention, even when it is difficult to form a cooling hole with a cast hole at the time of casting due to poor molten metal flow, a groove of the cooling hole is previously formed on the outer peripheral portion of the turbine casing at the time of casting. Since the lid is manufactured, a separately manufactured lid is put on the groove, and then the periphery of the lid is attached by welding, the cooling hole of the turbine casing can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a part of a process of manufacturing a turbine casing according to a first embodiment.
FIG. 2 is a perspective view showing a part of a state of the turbine casing after casting according to the first embodiment.
FIG. 3 is a perspective view of a lid that covers a groove according to the first embodiment.
FIG. 4 is an exemplary perspective view showing a part of a process of manufacturing a turbine casing according to the second embodiment;
FIG. 5 is a perspective view showing a part of a state of a turbine casing after casting according to a second embodiment.
FIG. 6 is a perspective view of a lid that covers a groove according to a second embodiment.
FIG. 7 is a cross-sectional view showing a part of a gas turbine. FIG. 8 is a schematic view showing a shape of a cast hole when casting a turbine casing according to a conventional example.
[Explanation of symbols]
1a, 1b: moving blade, 2a, 2b: stationary blade, 3: turbine casing, 4: passage portion, 5: cooling hole, 5 ': cast hole, 6: flange portion, 7: exhaust casing, 8: groove, 8a: stepped portion, 9: lid, 10: laser welded portion, 6: cooling hole in rear flange portion, 12: drill, 13: groove, 14: TIG welded portion, GAS: combustion gas.

Claims (4)

In a method for manufacturing a cast turbine casing having a plurality of cooling holes in an outer peripheral portion,
A molten metal is cast into a mold formed so that a plurality of axially extending grooves are formed in the outer peripheral portion of the cast turbine casing, and after solidification of the molten metal, a turbine casing as a casting is taken out from the mold. A method of manufacturing a turbine casing, comprising: covering the groove formed in the outer peripheral portion of the cast turbine casing with a lid; and welding the lid and the outer peripheral portion of the turbine casing to form a cooling hole. In a method for manufacturing a cast turbine casing having a plurality of cooling holes in an outer peripheral portion,
A molten metal is cast into a mold molded so as to form a plurality of axially extending grooves and a circumferential flange portion on the outer peripheral portion of the cast turbine casing, and after the molten metal is solidified, the molten metal is cast from the mold. Take out the turbine casing as a product, cover the groove formed in the cast turbine casing with a lid, weld this lid and the outer periphery of the turbine casing, drill holes in the flange by machining, and form cooling holes A method of manufacturing a turbine casing. The method according to claim 1, wherein a plurality of the grooves are covered with a lid, and the lid and an outer peripheral portion of the turbine casing are welded. 3. A step formed at an edge of the groove, a groove to be fitted with the step is formed in the lid, and a periphery of the lid is welded to a turbine casing. 3. The method for manufacturing a turbine casing according to 1.).

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