KR101140296B1 - Method for manufacturing blade ring for gas turbine by centrifugal casting - Google Patents

Abstract

PURPOSE: A method for centrifugal casting of a blade ring for a gas turbine is provided to minimize the inflow of molten metal through a joint between auxiliary molds. CONSTITUTION: A method for centrifugal casting of a blade ring for a gas turbine is as follows. Connection sides of auxiliary molds(40), which are installed in contact with each other, are radially arranged at a set angle in the rotational direction of a rotating plate. Molten metal(50) is injected into a centrifugal casting mold(30) while rotating the rotating plate, thereby forming a ring-shaped preform. The preform and the auxiliary molds connected to the preform are separated from the centrifugal casting mold. The auxiliary molds are removed from the preform. The preform is heat-treated and cut into a blade ring.

Description

Method for manufacturing blade ring for gas turbine by centrifugal casting

The present invention relates to a manufacturing method by centrifugal casting, and more particularly, to a manufacturing method by centrifugal casting of a blade ring for a gas turbine having excellent productivity and economy by a non-metal auxiliary mold having an efficient coupling structure.

In general, a blade blade for a turbine is a ring-shaped structure for supporting a blade (Moving Blade) in which the combustion gas is converted to the rotational power of the flow (Steam Flow) having the optimum steam direction, the rotational power is turbine turbine (Turbine Rotor) rotates the generator rotor to get useful power.

The outer portion of such a blade ring is assembled and fixed inside the casing of the turbine portion in the gas turbine, and a plurality of vanes are assembled and fixed inside the blade ring, such blade ring is the core device of the turbine portion most important in the gas turbine.

The blade ring is manufactured to have a bent portion in the outer diameter or the inner diameter, and for this purpose, in the related art, first, by heating an ingot (ingot), which is an intermediate material, a second type of cutting is performed by bending a straight bar into a ring shape by pressing and forging. This was applied. This method requires a lot of production time and cost due to the complicated manufacturing process, there is a fear of product failure if the uniformity of the cross-sectional uniformity of the metal material of the initial straight bar was poor. In addition, secondly, such a blade ring may be manufactured using sand casting, but the mechanical properties of the large sand casting product have low disadvantages.

In order to solve this problem, the ring-shaped mold is installed on the upper rotating plate rotated horizontally by the power unit, and the molten metal is injected into the inner space to produce the ring-shaped base material by the centrifugal force generated through the rotation and the secondary cutting. Centrifugal casting methods for manufacturing turbine blade rings through processing have been developed and used.

However, the base material manufactured by the centrifugal casting method has a problem in that it takes a lot of time for cutting processing time to form a plurality of bent parts such as grooves for coupling the sealing means to the inner circumference or the outer circumference. In addition, the adhesive phenomenon occurs in the process of contact with the mold body inner diameter in the state that the temperature of the molten metal is 1500 ℃ or more, there was also a problem that the mold body is deformed or damaged by thermal stress.

Thus, the molten metal is formed in the inner diameter of the centrifugal casting mold body so as not to contact the inner diameter of the centrifugal casting mold body so as to have a shape corresponding to a plurality of bent portions, such as a groove portion for coupling the sealing means to the inner or outer circumference of the manufactured base material. Techniques for installing ceramic segments have been developed.

However, in the actual production process, the arrangement is disturbed by the inertia generated when the ceramic segments closely placed on the inner circumference of the centrifugal casting mold body, and a nonuniform interval is generated between the segments, so that the molten metal is introduced and penetrated at the interval. In close contact with the inner circumference of the centrifugal casting mold body, there is a problem that still causes the conventional problems such as damage to the parts or the time required for the second cutting process.

In particular, the liquid molten metal flowing through the gap causes fine vortices or vortices to cause uneven flow, so that even after formation of the base material, the density of components is uneven in the corresponding portion, and the strength due to the local notch generation of the manufactured blade ring outer periphery. There was a serious problem that causes the product to degrade by lowering.

Korea Patent Registration No. 10-492195

The present invention is to solve the above problems to provide a manufacturing method by centrifugal casting of gas turbine blade ring excellent in productivity and economy by a non-metal auxiliary mold having an efficient coupling structure.

In order to solve the above problems, the present invention is to arrange the centrifugal casting mold on the upper surface of the rotating plate provided to be rotated by a hydraulic motor, a plurality of arc-shaped auxiliary mold formed on the inner surface of the inner wall surface of the centrifugal casting mold A first step of closely contacting each other, wherein the side to which the auxiliary molds are connected is arranged to be inclined at an angle set from a radial waterline from the center of rotation of the rotating plate; A second step of forming a ring-shaped base material by injecting molten metal into the centrifugal casting mold while rotating the rotating plate; A third step of separating the base material and the auxiliary mold coupled thereto from the centrifugal casting mold; Crushing to separate the auxiliary mold from the base material; And it provides a manufacturing method by centrifugal casting of the blade ring for a gas turbine comprising a fifth step of heat-treating the base material and cutting to form a blade ring.

Here, in the first step, the side connected to each of the auxiliary mold is preferably disposed to be inclined toward the rotation direction side of the rotating plate on the basis of the radial water line.

In addition, the auxiliary mold is provided with a refractory clay layer as a thickness set on the outer surface of the center core formed of a heat-resistant material, it is preferable to separate the auxiliary mold by crushing the refractory clay layer in the fourth step.

And, the side of each of the auxiliary mold is formed with an alignment groove and an alignment protrusion coupled to each other, the alignment protrusion has a convex outer surface so as not to be separated in the circumferential direction is formed in the alignment groove, the alignment protrusion in the first step It is preferable to connect the vertically inserted into the alignment groove of the adjacent auxiliary mold.

On the other hand, the present invention is a rotating plate provided to be rotated by a hydraulic motor; A centrifugal casting mold installed on an upper surface of the rotating plate; And installed close to the inner wall surface of the centrifugal casting mold, the predetermined bending is formed on the inner surface, the arrangement angle of the side portion to be connected is arranged to be inclined at an angle set in the direction of rotation of the rotating plate from the radial water line from the center of rotation of the rotating plate Provided is a manufacturing apparatus by centrifugal casting of a blade ring for a gas turbine including a plurality of arc-shaped auxiliary molds.

Through the above solution, the manufacturing method by centrifugal casting of the blade ring for a gas turbine of the present invention provides the following effects.

First, since the spacing between the side surfaces of the respective auxiliary molds is inclined to be close to the rotational direction of the rotating plate, the molten metal can be substantially blocked from flowing between the gaps, and the inflow through the gaps between the auxiliary molds. By minimizing the molten metal it is possible to block the occurrence of fine vortex to vortex. Through this, by maintaining the uniform flow and centrifugal casting state of the injected molten metal, even after the formation of the base material, the density and strength of the components distributed on the outer surface are maintained uniformly, thereby preventing the occurrence of local notches and significantly improving the product quality. You can.

Second, both sides of the adjacent auxiliary molds maintain a stable position without deviating each auxiliary protrusion even by inertia during rotation through the coupling structure of the alignment groove and the alignment protrusion, and the arrangement is disturbed by the centrifugal force even if each auxiliary mold is rotated. Closed connections between adjacent sub-moulds are maintained without being supported, thereby minimizing the influx of melt between them.

1 is a cross-sectional view of a manufacturing apparatus by centrifugal casting of a blade ring for a gas turbine according to an embodiment of the present invention.
Figure 2 is a cross-sectional view of the main part showing the structure of the base material by the manufacturing apparatus by centrifugal casting of the blade ring for the gas turbine according to an embodiment of the present invention.
Figure 3 is a perspective view of the base material produced by the manufacturing apparatus by centrifugal casting of the blade ring for the gas turbine according to an embodiment of the present invention.
Figure 4 is a flow chart showing a manufacturing method by centrifugal casting of the blade ring for the gas turbine according to an embodiment of the present invention.
Figure 5 is a perspective view of the auxiliary mold applied to the manufacturing apparatus by centrifugal casting of the blade ring for the gas turbine according to an embodiment of the present invention.
Figure 6 is a plan view showing the coupling and arrangement of the auxiliary mold applied to the manufacturing apparatus by centrifugal casting of the blade ring for the gas turbine according to an embodiment of the present invention.

Hereinafter, a manufacturing method by centrifugal casting of a blade ring for a gas turbine according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a manufacturing apparatus by centrifugal casting of a gas turbine blade ring according to an embodiment of the present invention, Figure 2 is a manufacturing apparatus by centrifugal casting of a gas turbine blade ring according to an embodiment of the present invention. It is sectional drawing of the principal part which shows the formation structure of the base material by this.

1 and 2, the manufacturing apparatus by centrifugal casting of the blade ring for the gas turbine is a rotary plate 20, the centrifugal casting mold 30 is rotatably provided to receive the power of the hydraulic motor (10). And, the sub mold 40 is included.

Here, the centrifugal casting mold 30 is installed on the upper surface of the rotating plate 20, when the molten molten metal 50 of the alloy ingot, such as stainless steel flows through the upper injection hole 60, the rotating plate 20 The molten metal is distributed in a ring shape by being in close contact with the inner wall surface side of the centrifugal casting mold 30 by the centrifugal force due to the rotation of the metal.

At this time, the auxiliary mold 40 is installed in close contact with the inner wall surface of the centrifugal casting mold 30, the auxiliary mold 40 is a plurality of grooves for coupling of the sealing means to be formed on the outer surface of the designed blade ring. Preset bends 40a, such as protrusions, are formed on the inner surface to correspond to the bent portions of.

Figure 3 is a perspective view of the base material produced by the manufacturing apparatus by centrifugal casting of the blade ring for the gas turbine according to an embodiment of the present invention.

Referring to FIG. 3, as the centrifugal casting mold rotates, the molten metal is in close contact with the inner surface of the auxiliary mold by centrifugal force to form a ring-shaped base material 51. At this time, in response to the bending of the auxiliary mold, a plurality of bent portions 51a are formed on the outer surface of the base material 51 such as a groove portion for coupling the sealing means. In this way, after the production of the base material 51, the amount of cutting for forming the grooves is reduced, thereby improving productivity and reducing the amount of molten metal supplied for the centrifugal casting, thereby reducing unnecessary energy to materials and processing. This can save you time and money.

On the other hand, Figure 4 is a flow chart showing a manufacturing method by centrifugal casting of the blade ring for the gas turbine according to an embodiment of the present invention.

As shown in FIGS. 1 to 4, first, the centrifugal casting mold 30 is disposed on the upper surface of the rotating plate 20 provided to be rotated by the hydraulic motor 10, and the inner wall surface of the centrifugal casting mold 30 is disposed. The predetermined curvature 40a is in close contact with the plurality of arc-shaped auxiliary molds 40 formed on the inner surface. At this time, as described later, the side to which each auxiliary mold 40 is connected is arranged to be inclined at an angle set from a radial waterline from the center of rotation of the rotating plate (s100).

Thereafter, while rotating the rotating plate 20, the molten metal 50 is injected into the centrifugal casting mold 30 to form a ring-shaped base material 51 (S110).

Next, the base material 51 and the auxiliary mold 40 coupled thereto are separated from the centrifugal casting mold 30 (s120), and the auxiliary mold 40 is crushed and separated from the base material 51. (S130).

In this case, the auxiliary mold 40 may be formed by firing refractory clay or bauxite, but is not limited thereto and may be provided with a refractory clay layer attached to the outer surface of the center core formed of a heat resistant material. In this case, the auxiliary mold 40 can be easily separated by crushing only the refractory clay layer formed on the outer surface of the central core. Here, the central core is formed of a rigid body made of a refractory material having a melting point higher than the melting point of the molten metal, and may be recycled by forming a refractory clay layer on its outer surface after crushing and separating.

Through this, the consumption of refractory clay can be reduced by the volume of the central core, thereby reducing the material cost and improving the economics.

Thereafter, the base material 51 formed as described above may be heat-treated and cooled, and cut through a precision machining factory such as CNC to form a blade ring having a desired design dimension (s140).

On the other hand, Figure 5 is a perspective view of the auxiliary mold applied to the manufacturing apparatus by centrifugal casting of the gas turbine blade ring according to an embodiment of the present invention, Figure 6 is a gas turbine blade ring according to an embodiment of the present invention Is a plan view showing the coupling and arrangement of the auxiliary molds applied to the manufacturing apparatus by centrifugal casting.

As shown in FIG. 5, an alignment groove 42 and an alignment protrusion 41 are formed at sides of each of the auxiliary molds 40, and the alignment protrusion 41 is formed in the alignment groove 42. It has a convex outer surface so as not to deviate in the circumferential direction. At this time, the shape of the alignment protrusion 41 and the alignment groove 42 may be formed in a variety of shapes as well as the shape of a circular or arc-shaped cross section.

Accordingly, the inner wall surface circumferential direction of the centrifugal casting mold (30 in FIG. 1) is connected by vertically inserting and connecting the alignment protrusion 41 formed on one side of the auxiliary mold 40 to the alignment groove 42 of the adjacent auxiliary mold. Accordingly, the auxiliary mold 40 may be assembled and arranged in a ring shape.

Through this, both side surfaces of the adjacent auxiliary mold 40 can maintain a stable position without each sub-mould 40 is separated by the inertia during rotation through the coupling structure of the alignment groove 42 and the alignment protrusion 41. have. In addition, the close connection between the adjacent sub-moulds can be maintained firmly to minimize the flow of the molten metal between them.

On the other hand, as shown in Figure 6, the side of each of the auxiliary mold 40 is connected to the direction of rotation of the rotary plate 30 on the basis of the radial line extending from the rotation center (C) of the rotary plate (30) The predetermined angle is disposed inclined.

Here, the molten liquid 50 injected in the state in which the rotating plate 30 is rotated at a high speed shows a tendency to stay in the rotational direction by inertia, while the auxiliary molds 40 are connected to each other. Since the side surface is disposed to be inclined by an angle θ set to the rotation direction side of the rotating plate 30 with respect to the radial water line, the molten metal 50 flows along the outer surface of the auxiliary mold 40. It can minimize the inflow into the gap between). This is due to the fact that the viscosity of the molten metal 50 is relatively high while the rotation speed of the rotating plate is high speed of 500 rpm or more.

That is, due to inertia and centrifugal force, the molten metal 50 flows radially outwards against the rotational direction of the rotating plate, and the flow angle of the molten metal is relatively opposite to the inclined direction of the side surface of the auxiliary mold 40. To achieve. Therefore, the molten metal flowing back against the rotational direction of the rotating plate 30 may flow substantially uniformly along the inner surface of the auxiliary mold rotated at high speed, and may be substantially blocked.

In addition, the molten metal (50) in contact with the outer surface of the auxiliary mold 40 is cooled in close contact with the initial rotation relatively close to the generation of the vortex can be blocked in advance.

As a result, the molten metal 50 flows smoothly along the outer surface of the auxiliary molds 40 rotated together with the rotating plate 20 and does not flow through the gap between the auxiliary molds 40. It may be distributed in density and cast.

Therefore, by minimizing the molten metal 50 introduced through the gap between the auxiliary molds 40 to block the occurrence of fine vortex or vortex to maintain a uniform flow, even after the formation of the base material density of the components distributed on the outer surface And by maintaining the strength uniformly it is possible to minimize the occurrence of local and fine notches to improve the quality of the product.

Of course, the side to be connected to each of the auxiliary mold 40 is not limited to being formed to be inclined in a straight line may be formed to be rounded in one direction.

As described above, the present invention is not limited to the above-described embodiments, but may be modified by those skilled in the art without departing from the scope of the claims of the present invention. Such modifications are within the scope of the present invention.

10: hydraulic motor 20: rotating plate
30: centrifugal casting mold 40: auxiliary mold
40a: bend 41: alignment protrusion
42: alignment groove 50: molten metal
51: base material 51a: bend

Claims (5)

The centrifugal casting mold is disposed on the upper surface of the rotating plate provided to be rotated by the hydraulic motor, and a plurality of arc-shaped auxiliary molds formed on the inner surface of the centrifugal casting mold are in close contact with each other. A first step of arranging and connecting the side surfaces of the rotary plate at an angle inclined from the radial line from the center of rotation of the rotary plate to the rotary direction side of the rotary plate;
A second step of forming a ring-shaped base material by injecting molten metal into the centrifugal casting mold while rotating the rotating plate;
A third step of separating the base material and the auxiliary mold coupled thereto from the centrifugal casting mold;
Crushing to separate the auxiliary mold from the base material; And
And a fifth step of heat-treating the base metal and cutting to form a blade ring. delete The method of claim 1,
The auxiliary mold is provided with a refractory clay layer attached to the outer surface of the central core formed of a heat-resistant material,
In the fourth step, the refractory clay layer is broken by the centrifugal casting of the blade ring for the gas turbine, characterized in that for separating the auxiliary mold. The method of claim 1,
Sides of the respective auxiliary molds are formed with alignment grooves and alignment protrusions that are coupled to each other, and the alignment protrusions have convex outer surfaces so as not to deviate in the circumferential direction by being joined to the alignment grooves.
The first step in the manufacturing method by centrifugal casting of the blade ring for the gas turbine, characterized in that for connecting the alignment projection vertically inserted into the alignment groove of the adjacent auxiliary mold. A rotating plate provided to be rotated by a hydraulic motor;
A centrifugal casting mold installed on an upper surface of the rotating plate; And
Is installed in close contact with the inner wall surface of the centrifugal casting mold, a predetermined bend is formed on the inner surface, the plurality of arrangement angle of the side portion connected to the angle set from the radial water line from the center of rotation of the rotating plate to the rotating direction side of the rotating plate A manufacturing apparatus by centrifugal casting of a blade ring for a gas turbine including two arc-shaped auxiliary molds.

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