KR101169214B1 - Hot forging method for superalloy material - Google Patents

Abstract

Disclosed is a hot forging method for a super heat resistant alloy material. Hot forging method for a super heat-resistant alloy material according to an aspect of the present invention, the step of manufacturing a cylindrical super-heat-resistant alloy preform having a ratio of height to diameter in a certain level range, upsetting by pressing down the preform Forming a preform, and joining the upper and lower steel plates to the upper and lower surfaces thereof, respectively, preparing the upper and lower molds for the open hot forging with the outer edges, and opening the upset preform into the open hot Positioning between the forging upper and lower molds to form the final forging.

Description

HOT FORGING METHOD FOR SUPERALLOY MATERIAL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot forging method for a super heat resistant alloy material, and more particularly, to a hot forging method for a product formed by a super heat resistant alloy material such as a turbine disk.

In the case of gas turbine engines used as power sources for aircraft and power generation, there is a tendency to increase the temperature and pressure of the combustion gas to increase the engine efficiency. 1 shows turbine disks 1, 2, 3 among the hot part parts of a gas turbine engine. The turbine disks 1, 2, 3 illustrated in FIG. 1 are composed of three stage disks, of which the first stage turbine disk 1 is the most complicated in shape and large in size. Turbine discs are hot components that support the turbine blades on the rotor, which serve to convert hot combustion gases into rotary motion. Therefore, it is necessary to support a turbine blade that rotates at high speed in a state exposed to high temperature and high pressure, and therefore, a material having excellent strength and creep characteristics at a high temperature is required. The material of the parts used in the high temperature parts satisfying these requirements is to prefer the super heat-resistant alloy material having excellent heat resistance.

However, the super-heat-resistant alloy material has a very poor properties compared to the hot formability of ordinary carbon steel because the strength at high temperature is similar to the strength at room temperature of ordinary carbon steel. As described above, in order to mold the superheat resistant alloy material having poor high temperature formability into a desired shape, the following hot forging method and constant temperature forging method are used.

FIG. 2 shows a general hot forging method for obtaining a disk of a desired shape by pressing the flat mold 4 above and below while the material is heated to a high temperature in order to lower the flow stress of the material. In FIG. 2, reference numeral 5 denotes an upsetted block, and reference numeral 6 denotes a rough product profile. At this time, since the mold 4 is in contact with the hot material in a state of being preheated to room temperature or to a temperature of about 150 to 400 degrees or less, the surface temperature of the material to be molded drops sharply. In the case of a material whose temperature has fallen, defects such as cracks are generated as the molding proceeds as the high temperature material is deformed. To prevent this, a method of increasing the amount of material or forming a simple mold shape is used.

The second method for manufacturing the turbine disk of the super heat-resistant alloy material is to use a constant temperature forging equipment as shown in FIG. Constant temperature forging is a method of forging by making the temperature of the metal mold | die 8 and 10 which shape a raw material, and the raw material 9 shape | forms into the same state. In FIG. 3, reference numeral 7 denotes a constant temperature forging heat shield, which blocks the molds 8 and 10 and the material 9 from the outside to maintain a constant temperature of the heated material 9 and the molds 8 and 10. Function This is to minimize the drop of the temperature of the raw material 9 by the molds 8 and 10 during forging by keeping the molds 8 and 10 at a high temperature.

When manufacturing a turbine disk through the conventional general hot forging and constant temperature forging method as described above, there are the following problems.

First, turbine disc manufacturing by general hot forging takes into account excessive forging allowance in consideration of the occurrence of cracks on the surface of the forging due to the temperature of the material falls into contact with the mold. In addition, the general hot forging method has a problem in that when the size of the turbine disk becomes large, the forming load becomes excessive and it cannot be molded. Therefore, when the turbine disk is manufactured by general hot forging using an expensive super heat-resistant alloy material, there is a problem that excessive material cost and the size of the moldable disk are limited to small.

In the case of constant temperature forging, which is the second of the existing manufacturing methods, it is difficult to determine the material of the molds 8 and 10 that must be maintained at the same temperature as the material to be molded. That is, when forming a super heat resistant alloy material, the strength of the super heat resistant alloy material at a high temperature is similar to that of ordinary steel at room temperature, so that a mold material capable of forming a super heat resistant alloy is very expensive and difficult to process. . Therefore, in order to manufacture a turbine disk using a constant temperature forging equipment, there is a problem in that the economic efficiency only if a large amount of production, and in the case of producing a small amount of economic efficiency.

Accordingly, the present invention has been made to solve the above-described problems, to provide a hot forging method for the super heat-resistant alloy material having excellent quality by combining the characteristics of the super-heat-resistant alloy material with excellent economic efficiency using hot forging. do.

Other objects of the present invention will become more apparent through the preferred embodiments described below.

Hot forging method for a super heat-resistant alloy material according to an aspect of the present invention, the step of manufacturing a cylindrical super-heat-resistant alloy preform having a ratio of height to diameter in a certain level range, upsetting by pressing down the preform Forming a preform, and joining the upper and lower steel plates to the upper and lower surfaces thereof, respectively, preparing the upper and lower molds for the open hot forging with the outer edges, and opening the upset preform into the open hot Positioning between the forging upper and lower molds to form the final forging.

Hot forging method for a super heat-resistant alloy material according to the present invention may include one or more of the following embodiments. For example, the ratio of height to diameter of the preform may be 2.0 or less. And the upper and lower steel plates can be formed by carbon steel.

And heating the upset preform, in which the upper and lower steel plates are combined, to a hot forging temperature, and preheating the upper and lower molds for open hot forging.

The present invention can provide a hot forging method for a super heat-resistant alloy material that can produce a forged product of high quality while reducing the manufacturing cost because it can use a general hot forging device without using a constant temperature forging device that requires a high cost Can be.

In addition, the present invention can provide a hot forging method for a super heat-resistant alloy material that can obtain a high material recovery rate that cannot be obtained by a general hot forging process.

1 is a diagram of a first stage, two stage and three stage turbine disk of a gas turbine engine.
2 is a view showing a conventional hot forging method.
3 is a view showing a conventional constant temperature forging equipment.
4 is a view showing a state where the cylindrical billet is located between the flat mold for upsetting.
5 is a diagram illustrating an upset billet.
6 is a view showing an upset preform.
7 is a view illustrating a state where the steel plate is coupled to the upper and lower surfaces of the upset preform, respectively.
8 is a view showing a general hot forging die.
9 is a view showing a state in which the preforms joined to the upper and lower steel plates are placed in the upper and lower molds for open hot forging.
10 is a view showing an example of performing a forging process using the upper and lower molds for open hot forging according to the present invention.
It is a figure which shows the final forging after hot forging by this invention.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout the specification and claims. The description will be omitted.

The hot forging method for the super heat-resistant alloy material according to the present invention includes the steps of manufacturing and designing a preform to enable molding of a material of an initial billet state in a forging die, and a method of hot forging a second preform. Divided. Turbine disk to which the present invention can be applied is a case in which the pressure reduction force of the hydraulic press is a capacity of about 7,000 tons, a nickel-based super heat-resistant alloy material having a diameter of 550mm and a size of 220mm in height. In addition, it is not a general upsetting disk but a forging having a shape of irregularities following the shape of the final product as shown in FIG. 11.

4 is a view showing a state in which the cylindrical billet 11 is located between the upsetting flat die 4, and FIG. 5 is a view showing the upset billet 11.

4 to 5, the cylindrical billet 11 is upsetting to a size capable of forging as an initial step for manufacturing the preform. The upset billet 11 or preform is cylindrical and has a constant height H0 and a diameter D0. At this time, in order to prevent defects such as buckling, folding or tearing when forging the upset billet 11, the ratio of the height to the diameter of the cylindrical preform (H0 / D0) ) Can be made 2.0 or less.

The preformed body formed as described above (formed) so that the ratio of the height to the diameter is 1.3 or less is pressed into a form that can be forged as shown in FIG. 6. 6 shows an upset preform 12 pressed down by a planar mold 4. The preform 12 formed as described above can be seen that the ratio of height to diameter is much reduced compared to the cylindrical preform of FIG. 5.

FIG. 7 illustrates a state in which steel plates 13 and 14 are coupled to upper and lower surfaces of the upset preform 12, respectively.

After the upset preform 12 is formed, the upper steel plate 13 and the lower steel plate 14 are coupled to the upper and lower surfaces of the preform 12, respectively, as shown in FIG. The upper and lower steel plates 13, 14 serve as lubrication between the molds 18, 19 and the molding material at high temperatures and heat shielding for hot forging dies (see 18 and 19 of FIGS. 8 to 10).

The material of the steel plates 13 and 14 according to the present embodiment may be general carbon steel. And the size and thickness of the steel plate (13, 14) can be determined based on the simulation results using a molding analysis program. The shape of the preform 12 of the super-heat-resistant alloy material is changed according to the size and thickness of the steel plates 13 and 14, and the shape of the final forged product is also affected. If the size of the steel plate 13, 14 is too large, the forging proceeds as a result of the folding phenomenon that the steel plates 13, 14 are folded and are stuck to the surface of the superheat-resistant alloy material or the steel plates 13, 14 are driven to one side. This happens. On the contrary, when too small, the heat blocking between the forging material and the molds 18 and 19, which are the original roles of the steel plates 13 and 14, is limited to a part.

And if the thickness of the steel plate (13, 14) is too thick in the process of forming the preform 12 of the super heat-resistant alloy, the steel plate (13, 14) in the unnecessary portion while pushing out the steel plate (13, 14) ) Is driven into the surface of the final forging. In addition, when the steel plates 13 and 14 are too thin, the heat shielding effect between the forging material and the molds 18 and 19 is reduced, and the buffering effect is also reduced. Thus, a phenomenon such as forging a super heat resistant alloy material with a general hot forging is performed. This happens.

Therefore, the size and thickness of the steel plate 13, 14 should be appropriately selected so that the above problems do not occur.

FIG. 8 is a view showing general hot forging dies 16 and 17.

As shown in FIG. 8, when the mold is completely closed, as in the conventional general hot forging dies 16 and 17, a very large reduction force is required in forging a material. In particular, since the super-alloy material has a 4 to 5 times higher flow stress at higher temperatures than ordinary carbon steel, a special mold design is particularly required to forge the super-alloy material with a small capacity press. In particular, in the case of using the closed hot forging dies 16 and 17, the portion where the forging reduction force is rapidly increased corresponds to the case where the material fills the outer portion 15.

In order to solve such a problem, the present invention uses the open hot forging dies 19 and 20 as shown in FIGS. 9 and 10. FIG. 9 shows a state in which the preforms 12, to which the upper and lower steel plates 13 and 14 are bonded, are placed on the open and forged upper and lower molds 19 and 20, and FIG. 10 is an open type according to the present invention. 1 is a diagram illustrating an example of performing the forging process using the upper and lower molds 19 and 20 for hot forging.

9 to 10, the upper and lower steel plates 13 and 14 are respectively bonded to the upper and lower surfaces of the preform 12 and heated to a hot forging temperature of about 850 to 1250 ° C., and then for open hot forging. It is positioned between the upper and lower molds 19 and 20. At this time, the upper and lower molds 19 and 20 for open hot forging are preheated and prepared at about 150 to 400 ° C. And when the upper mold 19 is lowered to the desired stroke, the outer portion 18 is open, so that the pressing force can be reduced drastically, while the outer portion 18 in the forging effect in terms of the forging effect of the disk from the cylindrical shape Since it is formed in the form, it is possible to obtain a sufficient forging effect.

FIG. 11 shows the final forged product 21 after hot forging obtained by performing the above process.

Although the above has been described with reference to an embodiment of the present invention, those skilled in the art may vary the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that modifications and variations can be made.

1, 2, 3: 1, 2, 3 turbine turbine disc 4: flat die for upsetting
7: constant temperature forging heat shield 8, 10: mold for constant temperature forging
11: billet 12: upset preform
13: upper steel plate 14: lower steel plate
15: outer part 16: hot forging upper mold
17: hot die forging lower mold 18: outer portion
19: open hot forging die
20: open hot forging die bottom mold
21: Final forging

Claims (4)

Preparing a cylindrical superheat-resistant alloy preform having a ratio of height to diameter in a predetermined range;
Pressing the preform to form an upset preform, and coupling upper and lower steel plates to upper and lower surfaces thereof, respectively;
Preparing upper and lower molds for open hot forging whose outer portions are open; And
And placing the upset preform between the upper and lower molds for open hot forging to form a final forged product. The method of claim 1,
The ratio of the height to the diameter of the preform is hot forging method for the super heat-resistant alloy material, characterized in that 2.0 or less. The method of claim 1,
The upper and lower steel plate is hot forging method for the super heat-resistant alloy material, characterized in that formed by carbon steel. The method of claim 1,
Heating the upset preform, in which the upper and lower steel plates are combined, to a hot forging temperature; And
And preheating the upper and lower molds for open hot forging.

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