Method of manufacturing ultra-large high strength turbine disc forged structure using rotate forging
Patent Information
- Application Number
- KR1020250015775
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-07
- Publication Date
- 2026-08-14
Smart Images
Figure PAT00001_ABST
Abstract
Description
Technology Field
[0001] The technical concept of the present invention relates to a method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging. Background Technology
[0002] High-strength superalloys such as Inconel 706 consist primarily of nickel, iron, and chromium; they possess high strength and corrosion resistance at high temperatures and are used as key materials in the aerospace and power generation industries. The aforementioned Inconel 706 is, 700 o It has excellent heat resistance that maintains high strength even in high-temperature environments above C, excellent corrosion resistance against oxidation and corrosion at high temperatures, maintains strong durability even under repetitive stress, provides structural stability even in extreme high-temperature environments, and has excellent weldability, which enables the fabrication of parts with complex structures and maintains high strength even after welding. Therefore, the Inconel 706 can be applied to the aerospace industry, such as high-temperature turbine blades, jet engine parts, and aircraft engines; the power generation industry, such as power plant gas turbine parts; the nuclear power industry, such as reactor parts that must maintain corrosion resistance and strength in high-temperature environments; and the automotive and marine industries, such as vehicle exhaust system parts and marine structures, where performance is critical in high-temperature and corrosive environments.
[0003] However, since the above Inconel 706 has very high strength, there is a limitation in that it is difficult to form a forged structure using a conventional forging process, and in particular, it is difficult to manufacture extra-large parts by a forging process. The problem to be solved
[0004] The technical problem that the technical concept of the present invention aims to solve is to provide a method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging.
[0005] However, these tasks are exemplary, and the technical concept of the present invention is not limited thereto. means of solving the problem
[0006] A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging according to the technical concept of the present invention for achieving the above technical problem may include: a pre-forming step of pre-forming a manufacturing target by performing at least one of upsetting and cogging on the manufacturing target; a manufacturing target placement step of placing the manufacturing target on a lower die for rotary forging; a first rotary forging step of forming a first region spaced apart from the center of the manufacturing target by applying pressure using an upper die for rotary forging; a manufacturing target rotation step of rotating the manufacturing target by rotating the lower die for rotary forging; and a second rotary forging step of forming a second region spaced apart from the center of the manufacturing target, different from the first region of the manufacturing target, by applying pressure using the upper die for rotary forging.
[0007] In one embodiment of the present invention, the extra-large high-strength turbine disk forged structure may be formed as a stepped structure on one side.
[0008] In one embodiment of the present invention, the step of rotating the manufacturing target and the second rotational forging step may be performed repeatedly.
[0009] In one embodiment of the present invention, the step of rotating the manufacturing target may be performed by rotating it clockwise or counterclockwise around the center of the manufacturing target.
[0010] In one embodiment of the present invention, the step of rotating the manufacturing target may be performed by rotating the lower mold for rotary forging at an angle ranging from 1 to 45 degrees.
[0011] In one embodiment of the present invention, the step of rotating the manufacturing target may be such that the lower mold for rotary forging is rotated at the same angle each time it is rotated.
[0012] In one embodiment of the present invention, before or during the performance of the preforming step, the first rotary forging step, or the second rotary forging step, the manufacturing target is 950 o C to 1250 o It can be heated at least once to a temperature in the C range.
[0013] In one embodiment of the present invention, the forged structure may have a cylindrical shape with dimensions ranging from 1200 mm to 1800 mm in diameter and 300 mm to 450 mm in thickness, and may have a protrusion in the center having a diameter ranging from 200 mm to 600 mm and a thickness ranging from 100 mm to 300 mm.
[0014] In one embodiment of the present invention, the protrusion may be formed on one surface of the forged structure or on both surfaces.
[0015] In one embodiment of the present invention, the forged structure may be made of stainless steel 304, stainless steel 316, or Inconel 706.
[0016] In one embodiment of the present invention, a method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging may include: a pre-forming step of pre-forming the manufacturing target by performing one or more of upsetting and cogging on the manufacturing target; a manufacturing target placement step of placing the manufacturing target on a lower die for rotary forging; a first face rotary forging step of forming a first protrusion by pressing and forming a first face of the manufacturing target using an upper die for rotary forging; a step of placing a lower opening die for rotary forging; and a second face rotary forging step of forming a second protrusion by pressing and forming a second face opposite to the first face of the manufacturing target using the upper die for rotary forging.
[0017] In one embodiment of the present invention, the first surface rotary forging step may include: a first rotary forging step of forming by pressing a first area spaced apart from the first central portion of the first surface of the manufacturing object using the upper die for rotary forging; a first manufacturing object rotation step of rotating the manufacturing object by rotating the lower die for rotary forging; and a second rotary forging step of forming by pressing a second area spaced apart from the first central portion of the manufacturing object, which is different from the first area of the manufacturing object, using the upper die for rotary forging.
[0018] In one embodiment of the present invention, the step of placing the lower opening mold for rotary forging may include: removing the object to be manufactured from the lower mold for rotary forging; placing the lower opening mold for rotary forging having an opening on the lower mold for rotary forging; and placing the object to be manufactured on the lower opening mold for rotary forging such that a first protrusion of the object to be manufactured is inserted into the opening provided in the lower opening mold for rotary forging.
[0019] In one embodiment of the present invention, the second surface rotary forging step may include: a third rotary forging step of forming by pressing a third region spaced apart from the second central portion of the second surface of the manufacturing object using the upper die for rotary forging; a second manufacturing object rotation step of rotating the manufacturing object by rotating the lower opening die for rotary forging; and a fourth rotary forging step of forming by pressing a fourth region spaced apart from the second central portion of the manufacturing object, which is different from the third region of the manufacturing object, using the upper die for rotary forging.
[0020] In one embodiment of the present invention, the extra-large high-strength turbine disk forged structure may be formed as a double-sided stepped structure. Effects of the invention
[0021] The method for manufacturing a super-large high-strength turbine disk forged structure using rotary forging according to the technical concept of the present invention allows for overall forging and forming by continuously forging and forming a super-large manufacturing target while rotating it, and can reduce the magnitude of the forming load applied for forging, and can facilitate the forging of super-large high-strength alloys that are difficult to forge due to their high strength, such as Inconel 706 alloy.
[0022] The effects of the present invention described above are illustrative and the scope of the present invention is not limited by these effects. Brief explanation of the drawing
[0023] FIGS. 1 and 2 are flowcharts illustrating a method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention. FIGS. 3 and 4 are schematic diagrams illustrating a rotary forging apparatus for performing a method of manufacturing an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention. FIG. 5 illustrates a rotary forging forming step in a method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention. FIG. 6 is a cross-sectional view illustrating an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention. FIG. 7 is a schematic diagram illustrating a method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention. FIG. 8 is a cross-sectional view illustrating an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention. FIGS. 9 and 10 are photographs of actual prototypes of a manufactured object manufactured by applying the method for manufacturing a super-large high-strength turbine disk forging structure according to an embodiment of the present invention, according to the manufacturing process steps. FIG. 11 shows various shapes and weights to which the method for manufacturing a super-large high-strength turbine disk forged structure according to one embodiment of the present invention is applied. FIGS. 12 to 17 describe an extra-large high-strength turbine disk forging structure formed by a method for manufacturing an extra-large high-strength turbine disk forging structure according to an embodiment of the present invention. Specific details for implementing the invention
[0024] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments of the present invention are provided to more completely explain the technical concept of the present invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the technical concept of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the technical concept of the present invention to those skilled in the art. In this specification, the same reference numerals denote the same elements throughout. Furthermore, various elements and areas in the drawings are depicted schematically. Accordingly, the technical concept of the present invention is not limited by the relative sizes or spacing depicted in the attached drawings.
[0025] Upsetting and cogging as described in this specification are commonly defined terms. For example, upsetting may refer to a process of reducing height and increasing cross-sectional area by applying axial pressure. Cogging may refer to a process of reducing thickness. The upsetting and cogging may be applied in directions perpendicular to each other.
[0026] A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging according to the technical concept of the present invention provides a method for forming a forged structure of a high-strength material such as Inconel 706 using a forging process.
[0027] Inconel 706 is a Ni-Fe-Cr precipitation-hardening alloy that is a high-strength alloy with excellent machinability and high-temperature properties, and possesses excellent machinability. Specifically, 870 o C to 1150 o Excellent hot formability in the C range, and 980 o C to 1150 o Mechanical properties are excellent when formed in the C range. Additionally, surface finishing may be required prior to forging, thermal management is required during and after forging, and grain growth needs to be inhibited.
[0028] The above Inconel 706 comprises iron (Fe): 35 wt% to 45 wt%, chromium (Cr): 14 wt% to 17 wt%, and the remainder being nickel (Ni) and unavoidable impurities. Additionally, the above Inconel 706 may further comprise molybdenum (Mo): 1.0 wt% to 2.0 wt% and titanium (Ti): 0.6 wt% to 1.0 wt%. Additionally, the above Inconel 706 may comprise iron (Fe): 35 wt% to 45 wt%, chromium (Cr): 14 wt% to 17 wt%, molybdenum (Mo): 1.0 wt% to 2.0 wt%, titanium (Ti): 0.6 wt% to 1.0 wt%, and the remainder being nickel (Ni) and unavoidable impurities.
[0029] In the forging process, a workpiece is placed between an upper mold and a lower mold, and then the upper mold presses or strikes the workpiece to produce a product.
[0030] The rotary forging process is a method of repetitive forming that applies a local load to a workpiece by rotating a mold. The rotary forging process described above includes an upper mold rotation method, in which the upper mold is rotated, and a lower mold rotation method, in which the lower mold is rotated. The upper mold rotation method has limitations in that it is difficult to scale up to a size of 8,000-ton forming load, as it has low compatibility with existing equipment and presents difficulties in equipment maintenance and repair. Additionally, in the case of the upper mold rotation method, there are limitations in equipment design because the rotating device must be mounted on the mold fixing part on the lower surface of the press's crosshead. On the other hand, the lower mold rotation method has the advantage of high equipment flexibility, such as the rotating device being able to be installed as a separate device without needing to be attached to the press. Therefore, in the present invention, the lower mold rotation method is applied in the rotary forging process.
[0031] FIGS. 1 and 2 are flowcharts illustrating a method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention.
[0032] Referring to FIG. 1, a method (S200) for manufacturing a super-large high-strength turbine disk forged structure using rotary forging comprises: a pre-forming step (S210) of pre-forming a manufacturing target by performing one or more of upsetting and cogging on the manufacturing target; a manufacturing target placement step (S220) of placing the manufacturing target on a lower die for rotary forging; a first rotary forging step (S230) of forming a first area spaced apart from the center of the manufacturing target by pressing it using an upper die for rotary forging; a manufacturing target rotation step (S240) of rotating the manufacturing target by rotating the lower die for rotary forging to rotate the manufacturing target; and a second rotary forging step (S250) of forming a protrusion by forming a second area spaced apart from the center of the manufacturing target, which is different from the first area of the manufacturing target, by pressing it using the upper die for rotary forging.
[0033] The extra-large high-strength turbine disk forging structure formed by performing the manufacturing method (S200) of the extra-large high-strength turbine disk forging structure of FIG. 1 may have a shape having a protrusion protruding from the central part of one surface. The extra-large high-strength turbine disk forging structure may be formed as a stepped structure on one surface.
[0034] The above preliminary forming step (S210) may be configured to sequentially perform an upsetting step and a cogging step, and may also be configured to repeat each step multiple times.
[0035] The above manufacturing object rotation step (S240) and the above second rotational forging step (S250) may be performed repeatedly. The number of such repetitions may be determined as the number of times the entire surface area of the manufacturing object is pressed.
[0036] The first rotary forging step (S230) and the second rotary forging step (S250) may be performed by the upper die for rotary forging pressing or striking the workpiece to be manufactured.
[0037] In order to perform the above manufacturing object rotation step (S240), the upper mold for rotary forging can be moved to be spaced apart from the manufacturing object.
[0038] The above manufacturing object rotation step (S240) may be performed by rotating the manufacturing object in a clockwise or counterclockwise direction around the center of the manufacturing object. The above manufacturing object rotation step (S240) may be performed by rotating the lower die for rotary forging at an angle ranging from 1 degree to 45 degrees. The above manufacturing object rotation step (S240) may be performed by rotating the lower die for rotary forging at the same angle each time it is rotated.
[0039] Before or during the performance of the above pre-forming step (S210), the above first rotary forging step (S230), or the above second rotary forging step (S250), the manufacturing object, for example, 950 o C to 1250 o It can be heated at least once to a temperature in the C range. The heating temperature may vary depending on the material and process conditions of the object to be manufactured.
[0040] Referring to FIG. 2, a method (S300) for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging comprises: a pre-forming step (S310) of pre-forming the manufacturing target by performing one or more of upsetting and cogging on the manufacturing target; a manufacturing target placement step (S320) of placing the manufacturing target on a lower mold for rotary forging; a first surface rotary forging step (S330) of forming a first protrusion by pressing and forming a first surface of the manufacturing target using an upper mold for rotary forging; a step (S340) of placing a lower opening mold for rotary forging; and a second surface rotary forging step (S350) of forming a second protrusion by pressing and forming a second surface opposite to the first surface of the manufacturing target using the upper mold for rotary forging.
[0041] The above pre-molding step (S310) and the above manufacturing target placement step (S320) may be the same or similar as the above pre-molding step (S210) and the above manufacturing target placement step (S220) described with reference to FIG. 1.
[0042] The first surface rotary forging step (S330) comprises: a first rotary forging step (S331) of forming a first area spaced apart from the first central portion of the first surface of the manufacturing object by applying pressure using the upper die for rotary forging; a first manufacturing object rotation step (S332) of rotating the manufacturing object by rotating the lower die for rotary forging; and a second rotary forging step (S333) of forming a second area spaced apart from the first central portion of the manufacturing object, different from the first area of the manufacturing object, by applying pressure using the upper die for rotary forging.
[0043] The step of placing the lower opening mold for rotary forging (S340) comprises: removing the object to be manufactured from the lower mold for rotary forging; placing the lower opening mold for rotary forging having an opening on the lower mold for rotary forging; and placing the object to be manufactured on the lower opening mold for rotary forging such that a first protrusion of the object to be manufactured is inserted into the opening provided in the lower opening mold for rotary forging.
[0044] The second surface rotary forging step (S350) comprises: a third rotary forging step (S351) of forming a third area spaced apart from the second central portion of the second surface of the manufacturing object by applying pressure using the upper die for rotary forging; a second manufacturing object rotation step (S352) of rotating the manufacturing object by rotating the lower opening die for rotary forging; and a fourth rotary forging step (S353) of forming a fourth area spaced apart from the second central portion of the manufacturing object, different from the third area of the manufacturing object, by applying pressure using the upper die for rotary forging.
[0045] The super-large high-strength turbine disk forging structure formed by performing the manufacturing method (S300) of the super-large high-strength turbine disk forging structure of FIG. 2 may have a shape having a first protrusion protruding from the first central part of the first surface and a second protrusion protruding from the second central part of the second surface opposite to the first surface. The super-large high-strength turbine disk forging structure may be formed as a double-sided stepped structure.
[0046] The above preliminary forming step (S310) may be configured to sequentially perform an upsetting step and a cogging step, and may also be configured to repeat each step multiple times.
[0047] The first manufacturing object rotation step (S332) and the second rotational forging step (S333) may be performed repeatedly. The second manufacturing object rotation step (S352) and the fourth rotational forging step (S353) may be performed repeatedly. The number of such repetitions may be determined as the number of times the entire surface area of the manufacturing object is pressed.
[0048] The first surface rotary forging step (S330) and the second surface rotary forging step (S350) may be performed by the upper die for rotary forging pressing or striking the workpiece.
[0049] In order to perform the first manufacturing object rotation step (S332) and the second manufacturing object rotation step (S352), the upper mold for rotary forging can be moved so as to be spaced apart from the manufacturing object.
[0050] The first manufacturing object rotation step (S332) and the second manufacturing object rotation step (S352) can be performed in the same manner as the manufacturing object rotation step (S140).
[0051] Before or during the performance of the above pre-forming step (S310), the above first plane rotary forging step (S330), or the above second plane rotary forging step (S350), the manufacturing object, for example, 950 o C to 1250 o It can be heated at least once to a temperature in the C range. The heating temperature may vary depending on the material and process conditions of the object to be manufactured.
[0052] FIGS. 3 and 4 are schematic diagrams illustrating a rotary forging apparatus for performing a method of manufacturing an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention.
[0053] Referring to FIG. 3, the rotary forging device (200) includes a lower die (210) for rotary forging in which a workpiece (20) is placed on the upper side, an upper die (220) for rotary forging placed on the upper side of the workpiece (20) and applying pressure, a rotary drive unit (230) for rotating the lower die (210) for rotary forging, and a press unit (240) for providing pressure to the upper die (220) for rotary forging.
[0054] Referring to FIG. 4, a rotary forging device (200a) comprises a lower opening mold (250) for rotary forging in which a workpiece (20) is placed on the upper side, an upper mold (220) for rotary forging placed on the upper side of the workpiece (20) to apply pressure, a rotary driving unit (230) for rotating the lower mold (210) for rotary forging, and a press unit (240) for providing pressure to the upper mold (220) for rotary forging. The lower opening mold (250) for rotary forging has an opening (252), and a first protrusion (28) of the workpiece (20) is inserted into the opening (252).
[0055] FIG. 5 illustrates a rotary forging forming step in a method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention.
[0056] Referring to FIG. 5, a manufacturing object (20) placed on a lower mold (210) for rotary forging is first pressed by an upper mold (220) for rotary forging. The area of the manufacturing object (20) that is first pressed by the upper mold (220) for rotary forging is a first area (21) and is spaced apart from the central part (c) of the manufacturing object (20).
[0057] Next, the lower die (210) for rotary forging is rotated to rotate the workpiece (20). The workpiece (20) is secondarily pressed by the upper die (220) for rotary forging. The area of the workpiece (20) that is secondarily pressed by the upper die (220) for rotary forging is the second area (22). As the workpiece (20) rotates, the second area (22) becomes a different area from the first area (21), and a part of the second area (22) may overlap with the first area (21).
[0058] In this way, a third region (23), a fourth region (24), a fifth region (25), and a sixth region (26) can be formed by the rotation of the lower mold (210) for rotary forging and the pressure applied by the upper mold (220) for rotary forging. Additionally, if necessary, the manufacturing target (20) can be rotated again and then pressured again, and the pressure can be applied to the first region (21) of the manufacturing target (20) in the same way as the first pressure.
[0059] In FIG. 5, the entire surface of the manufacturing target (20) can be pressed by six pressurizations. However, this is exemplary and the number of pressurizations can be varied.
[0060] The above rotary forging step can be applied to the first to fourth rotary forging steps described above. Additionally, the lower die (210) for rotary forging can be replaced with a lower opening die (250) for rotary forging.
[0061] A protrusion may be formed in the center (c) by such pressure. The protrusion may be a first protrusion formed on the first surface of the manufacturing object (20) or a second protrusion formed on the second surface of the manufacturing object (20).
[0062] Accordingly, the method for manufacturing a super-large high-strength turbine disk forged structure according to the present invention allows for overall forging and forming by continuously forging and forming a super-large manufacturing target while rotating it, and can reduce the magnitude of the forming load applied for forging, and can facilitate the forging of super-large high-strength alloys that are difficult to forge due to their high strength, such as Inconel 706 alloy.
[0063] The forged structure may have a cylindrical shape with dimensions ranging from 1200 mm to 1800 mm in diameter and 300 mm to 450 mm in thickness. Additionally, it may have a protrusion in the center having a diameter ranging from 200 mm to 600 mm and a thickness ranging from 100 mm to 300 mm. The protrusion may be formed on one side or on both sides of the forged structure.
[0064] The above-mentioned forged structure may be made of, for example, stainless steel 304, stainless steel 316, or Inconel 706. However, the dimensions and material of the above-mentioned forged structure are exemplary, and the technical concept of the present invention is not limited thereto.
[0065] The upper die for rotary forging described above may have a length in the range of 1000 mm to 1800 mm and a width in the range of 300 mm to 800 mm. However, the dimensions of the upper die for rotary forging described above are exemplary, and the technical concept of the present invention is not limited thereto.
[0066] The upper die for rotary forging described above may have a length equal to or greater than the diameter of the workpiece being manufactured, and may have a width smaller than the diameter of the workpiece being manufactured. Accordingly, the surface area of the upper die for rotary forging in contact with each other may be smaller than the surface area of the workpiece being manufactured.
[0067] Since the surface area of the upper die for rotary forging is smaller than the surface area of the object to be manufactured, the entire surface area of the object to be manufactured cannot be pressed by the upper die for rotary forging in a single forging operation. Therefore, by performing rotary forging in which the object to be manufactured is rotated and continuously pressed by the upper die for rotary forging, the desired surface area of the object to be manufactured can be pressed.
[0068] In addition, as the upper die for rotary forging repeatedly rotary forges the above-mentioned manufacturing object, the pressurized areas of the above-mentioned manufacturing object may overlap. The amount of overlap of the areas of the above-mentioned manufacturing object pressed by the upper die for rotary forging may be, for example, in the range of 20% to 50%. However, the amount of overlap of the above-mentioned manufacturing object is exemplary, and the technical concept of the present invention is not limited thereto.
[0069] The amount of reduction applied by rotary forging to the above-mentioned manufacturing target may be divided into two or more steps. For example, the amount of reduction applied by rotary forging to the above-mentioned manufacturing target may be divided into a number of steps ranging from 2 to 10. However, the number of divisions is exemplary, and the technical concept of the present invention is not limited thereto.
[0070] Experimental Example
[0071] Preferred experimental examples are presented below to aid in understanding the present invention. However, the following experimental examples are intended only to aid in understanding the present invention and do not limit the present invention. Details not described herein can be sufficiently technically inferred by those skilled in the art, so their description is omitted.
[0072] The extra-large, high-strength turbine disk forged structure using rotary forging was designed as a large turbine disk having a diameter of 1,550 mm or more and a thickness of 500 mm or more. To reduce the cost of expensive raw materials, it may be shaped with a step. The raw material required to manufacture the turbine disk can be designed to be approximately 6,000 tons, and based on this, product shapes and process reviews for each shape were conducted. As shown in Fig. 6, shapes with a step on one of the upper or lower surfaces and shapes with a step on both surfaces were reviewed. Considering material loss during the process, the analysis was based on a maximum dimension of 5,900 kg.
[0073] FIG. 6 is a cross-sectional view illustrating an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention.
[0074] Referring to FIG. 6, (a) is a one-sided stepped structure and is an extra-large high-strength turbine disk forged structure, and (b) is a two-sided stepped structure and is an extra-large high-strength turbine disk forged structure. The dimensions of the structures are indicated in the drawing.
[0075] Due to the heavy weight characteristics of the product, a high load is required. Considering that a load of 6,000 tons was required to form a forging with an outer diameter of 1,018 mm and a thickness of 184 mm when using a lower die for shaping, forming within the equipment load limit may be impossible. Even when utilizing a die with an upper shape, forming within the load limit requires the use of a very narrow die, making it difficult to secure sufficient overlap. Furthermore, even if sufficient overlap is secured, processability is significantly reduced, which may lead to an increase in the number of heating cycles.
[0076] Therefore, in order to form a step (i.e., a protrusion) in the central part, a method was selected to impart a shape to the upper surface through repetitive molding using a flat mold.
[0077] Next, the molding process of a product having a step difference in the center in both directions was examined. When using a mold with a lower shape, the load increases rapidly, and a process was established to resolve this and impart the shape.
[0078] Accordingly, a method was selected in which a process of forming a protrusion on the first surface was performed first, the formed protrusion was placed on a lower mold having an opening that supports the protrusion without damage, and then the second surface was formed again. In such cases, an increase in the number of reheating cycles may be essential.
[0079] FIG. 7 is a schematic diagram illustrating a method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention.
[0080] Referring to FIG. 7(a), a manufacturing method for forming an extra-large high-strength turbine disk forged structure as a one-sided stepped structure is illustrated, and a first protrusion (28) is formed on one side of the manufacturing target (20).
[0081] Referring to FIG. 7(b), a manufacturing method for forming an extra-large high-strength turbine disk forged structure as a double-sided stepped structure is illustrated, wherein a first protrusion (28) is formed on one side of the manufacturing target (20), and a second protrusion (29) is formed on the other side of the manufacturing target (20).
[0082] Next, a detailed process design was carried out for the production of a prototype of an extra-large high-strength turbine disk forged structure. The raw material for the disk was Inconel 706, with an outer diameter of 1120 mm, a height of 700 mm, and a weight of 5549 kg. To produce a prototype of an extra-large high-strength turbine disk forged structure with a diameter of 1550 mm and a height of 500 mm or more, a design of the prototype shape and dimensions was performed to satisfy the target dimensions, enable production within a limited weight, and reflect the shape and dimensions of the final processed product.
[0083] FIG. 8 is a cross-sectional view illustrating an extra-large high-strength turbine disk forged structure using rotary forging according to an embodiment of the present invention.
[0084] Referring to FIG. 8, a perspective view of an extra-large high-strength turbine disk forged structure is shown in (a), and a cross-sectional view and dimensions are shown in (b).
[0085] The forged structure of Fig. 8 has a step (i.e., a protrusion) formed on only one side, taking into account the additional reheating required when forming steps on both sides. If the number of reheating cycles increases, material properties may deteriorate due to microstructure coarsening. Therefore, when forming steps on both sides of a cylindrical raw material without preforming, two or more reheating cycles may be required compared to a step on one side. The material heating temperature for forging is 1120°C o It was set to C. The above temperature was selected to inhibit tissue coarsening.
[0086] As an example of the manufacturing method of the super-large high-strength turbine disk forged structure of the present invention, a rotating device for rotary forging of a turbine disk was designed. The rotating device was designed such that a forming load of approximately 8,000 tons is applied to the central part or its surroundings. In addition, considering the forming load, detailed specifications and quantities for springs, bearings, etc. were selected based on the specifications of the drive unit, and kinematic analysis reflecting this was performed to design a final drawing consisting of a drive unit, an upper and lower frame, and a top plate, and a control system for controlling the device was designed to manufacture the rotating device.
[0087] Preliminary experiments were conducted to verify the fabricated rotating device and to pre-examine the subsequent turbine disk manufacturing process. For the manufacturing target, stainless steel was used instead of the expensive Inconel material. Subsequently, an actual prototype of the manufacturing target was produced. To this end, a mold was fabricated by sequentially performing design, forging, heat treatment, and machining, and an actual prototype was produced using the said mold. The manufacturing process consisted of an upsetting stage, a cogging stage, and a final rotating forging stage. For the final rotating forging stage, a lower die rotation method was selected.
[0088] FIGS. 9 and 10 are photographs of actual prototypes of a manufactured object manufactured by applying the method for manufacturing a super-large high-strength turbine disk forging structure according to an embodiment of the present invention, according to the manufacturing process steps.
[0089] Referring to Fig. 9, photographs of preliminary tests conducted using stainless steel prior to the fabrication of a prototype using Inconel 706 are shown. Depending on the material properties, the appropriate heating temperature is 1250 oHeating was performed at C. Since the material had not undergone a prior forging process to ensure internal integrity, upsetting and cogging were performed to ensure integrity. Subsequently, rounding and upsetting were performed, followed by rotary forging. For the purpose of the preliminary test, process characteristics were examined by applying light and heavy compression compared to the dimensions of the target for development. No equipment issues occurred, and it was confirmed that it is possible to form a target product of excellent quality in terms of process and product. However, considering the high-temperature strength of Inconel 706 and prior research results regarding forming load, a higher load is required compared to stainless steel, so further consideration of additional measures may be necessary.
[0090] Referring to Fig. 10, photographs of preliminary tests conducted using Inconel 706 are shown. Considering the increased load during the manufacturing process of the Inconel 706 turbine disk forged structure, a flat die with a width of 650 mm was fabricated and used for rotary forging. 1120 o The material heated to C was upset using a rotary forging process to form it to the final dimensions. The process can be divided into a first upset process to form the central part to the target dimensions and a second forming process to form the parts outside the central part to the target dimensions, and a reheating of 2 hours was performed between the first upset and the second upset.
[0091] When the entire area was compressed during the first upsetting, it was impossible to reduce it to the target dimensions due to load constraints, so additional reduction was performed using rotary forging. It was confirmed that smooth forming to the final target dimensions was achieved through local forming in both the first and second processes; specifically, the roughing amount was 5.0 mm compared to the target value of 7 mm or less, and 1635.3 mm compared to the disk diameter of 1550 mm or more. Thus, the effectiveness of the proposed process was verified.
[0092] Accordingly, the final prototype of the extra-large high-strength turbine disk forged structure formed from Inconel 706 could be formed into the final target shape through one reheat without any issues during the process.
[0093] A review was conducted regarding the forging shape, weight, and manufacturing process for fabricating an ultra-large, high-strength turbine disk forged structure. Considering the high cost of materials, a preliminary review was conducted on the weight reduction effects when applying the shape.
[0094] FIG. 11 shows various shapes and weights to which the method for manufacturing a super-large high-strength turbine disk forged structure according to one embodiment of the present invention is applied.
[0095] Referring to FIG. 11, (a) is a form without a step and has a weight of 4266 kg, (b) is a form with a step in one direction in the center and has a weight of 4178 kg, (c) is a form with a step in one direction in the end and has a weight of 4053 kg, and (d) is a form with a step in the center and a step in the end and has a weight of 4002 kg. Compared to the form without a step (a), the weight reduction amounts were found to be 88 kg for (b), 213 kg for (c), and 264 kg for (d), respectively. Therefore, it was confirmed that applying a step in the end is more effective than applying a step in the center. In particular, regarding the additional process for applying a step in the center, further research on efficiency may be necessary when considering the increase in the number of reheating cycles, the increase in process time, and the increase in process costs relative to the weight reduction.
[0096] Subsequently, detailed design was carried out for the fabrication of small and medium-sized turbine disks. For the form without steps, a post-forging weight of 4,266 kg was required, and for the form with steps at the ends, 4,053 kg was required; however, since the usable material was limited to 2,884 kg, the design was re-executed based on the height of the target product. In terms of analyzing the effects of reheating and forging ratios, the review of the load during billetizing revealed that 1120, which is expected to require a high load, o Even under C upsetting process conditions, it is expected to be up to 3089 tons, so it was determined that testing would be possible within the equipment specifications.
[0097] FIGS. 12 to 17 describe an extra-large high-strength turbine disk forging structure formed by a method for manufacturing an extra-large high-strength turbine disk forging structure according to an embodiment of the present invention.
[0098] Referring to FIG. 12(a), the shape and dimensions of an extra-large high-strength turbine disk forged structure made of a three-stage single-sided stepped structure are shown. The three-stage single-sided stepped structure has a diameter of 1700 mm or more, a thickness of 500 mm or more, and three steps.
[0099] Referring to Fig. 12(b), the shape and dimensions of an extra-large, high-strength turbine disk forged structure made of a double-sided stepped structure are shown. The double-sided stepped structure was implemented for the purpose of verifying actual turbine disk application and is a product intended to confirm the possibility of securing economic feasibility through UT characteristics and raw material reduction.
[0100] These are forms that increase the outer diameter by applying additional compression to the outer diameter to create a step. Since Inconel 706 is expensive and difficult to process, forming it into a shape close to the final product during the forging process yields significant benefits. Considering this, a design was carried out that reflected the shape of the final processed product and the weight of the raw material, and the shape and dimensions of the disc prototype for commercialization verification were selected. By creating a step on both the top and bottom surfaces, weight can be reduced, and the diameter was the target value of 1700 mm.
[0101] A forging process design was performed to fabricate a three-stage single-sided stepped structure. During the process, additional reduction was applied to the outer diameter of the existing prototype to create a step and increase the diameter. Although an increase in process time is expected due to the additional reduction, considering that the reduction amount is not large (approximately 80 mm), the final shape and dimensions can be secured with only one reheating cycle without increasing the number of reheating cycles.
[0102] The heating temperature is 1120 o It was set to C, as an increase in forging temperature can lead to growth in microstructure size. Changes in shape cause an increase in forming load due to factors such as increased working time due to additional reduction, decreased material temperature, increased load resulting from this, thinning of the outer diameter, increased deformation resistance, and increased load resulting from this. As a solution to overcome this, rotary forging was performed using high-load press equipment.
[0103] Since the above structures require a lower shape mold due to the characteristic of having shapes on both the upper and lower sides, a lower shape mold was designed based on the disc shape design, taking into account the dimensions at the forging temperature. The most significant feature reflected in the mold design is that the curvature of the stepped section has been greatly increased compared to the prototype design; this is intended to allow for smooth flow by reducing the material's resistance to deformation through the application of a larger curvature. Additionally, an insert-type separable mold was applied to the central section to enable the removal of the molded product after the process is completed.
[0104] Finite element analysis is the commercial finite element analysis program Forge TM It was performed using ). In this case, when implementing rotary forging, an MPFX file was utilized to simplify the implementation of multi-pass forming within the program. While utilizing the above MPFX file can somewhat simplify the setting of iterative analysis conditions for the analysis of the multi-pass forming process, the analysis execution time increases due to the characteristics of the process in which a large number of reductions occur, and modification of the analysis model may be required to accurately reflect the actual process characteristics.
[0105] Referring to Fig. 13(a), the results of a finite element analysis were performed to verify the suitability of the designed lower mold. An analysis was conducted on the disc manufacturing process using the designed lower mold shape. For the purpose of the analysis to verify the filling behavior of the stepped portion due to the shape of the lower mold, an upsetting process was applied to reduce the volume by 402.5 mm, and the resulting deformation behavior was verified.
[0106] Referring to Figures 13 (b) and (c), the shape change of the manufactured object before and after compression is shown.
[0107] Referring to Fig. 13 (d), the step portion filling pattern of the manufactured object after compression is shown. As shown in the analysis results, the material is formed in a way that completely fills the step portion of the mold after compression, and it was confirmed that additional mold shape modification for filling the step portion is unnecessary.
[0108] Referring to Fig. 14, the forming load during upsetting is a maximum of 34,830 tons, and it was determined that the application of a rotary forging process to reduce the forming load is absolutely necessary.
[0109] The process steps for the ultra-large, high-strength turbine disk forged structure are as follows. The raw material is 1120 o After heating to C, the final target shape was formed with one reheating cycle. During the process, the lower die used a designed shape die, and the upper die was formed under maximum load using an upsetting die, followed by localized repetitive forming, i.e., rotary forging, using a flat die.
[0110] The raw material for the ultra-large high-strength turbine disc forged structure was 5,350 kg for the production of the 3-stage single-sided stepped structure and 5,700 kg for the double-sided stepped structure, and was supplied with an additional amount of about 2% compared to the weights of 5,224 kg and 5,598 kg in the process design. Although dimensional changes are essential in the case of a weight shortfall, since the weight was overweight, the process was carried out without changing the existing design, and the excess weight was allocated as an additional margin depending on the conditions during actual operation.
[0111] Referring to FIG. 15, a process step for manufacturing an extra-large high-strength turbine disk forged structure as a three-stage single-sided stepped structure according to the forging process design described above is shown.
[0112] The material forging temperature is 1120 o When heated to C, furnace temperature standard 100 per hour o The temperature was increased at a rate of C, and a sufficient holding time was given to reach the forging temperature inside the raw material.
[0113] During the first upsetting stage, which involves reducing the entire surface of the material to the primary target thickness (i.e., 500 mm based on the cold dimension of the thickest part), the material was compressed to the equipment's maximum load using a die capable of simultaneous reduction of the entire raw material area. Subsequently, rotary forging was performed using a flat die with a width of 900 mm to reduce the number of forging operations and time, resulting in a total processing time of approximately 10 minutes. After the completion of this process, 1120 o It was loaded into a heating furnace of C and reheated for 40 minutes.
[0114] Next, rotary forging was performed to form the shape to the final target. At this time, considering that the forming load increases as the thickness of the material decreases, the upper die was changed to a flat die with a width of 500 mm, and the final dimensional forming was achieved through a process of about 15 minutes using the die. No additional surface cracking was observed in the hot-worked forging.
[0115] As the double-sided stepped structure requires a lower shape mold, the mold was manufactured by forging, heat treating, and machining according to the design.
[0116] Referring to FIGS. 16 and 17, process steps for manufacturing an extra-large, high-strength turbine disk forged structure as a double-sided stepped structure according to the forging process design described above are shown. FIG. 16 is for the case of stainless steel, and FIG. 17 is for the case of Inconel 706.
[0117] Prior to the fabrication of prototypes using Inconel 706 raw material, mold design and process verification using stainless steel were conducted. Conditions other than the heating temperature were managed in accordance with the previously established process specifications, and the heating temperature was 1250 oIt was set to C. At this time, the raw material was pre-fabricated into a circular billet shape and the test was conducted. This reflects the purpose of fabrication to verify process characteristics in advance by forming the material into a shape similar to the Inconel 706 raw material.
[0118] The process was carried out in the order of upsetting and rotary forging to secure a primary height (320 mm based on the center), followed by additional rotary forging to secure a secondary height (245 mm based on the outer edge). Reheating was performed for approximately 120 minutes during the process.
[0119] While the final molded product showed no significant issues on the side of the lower central step, some infill was observed at the outer corners. This is a common phenomenon during shape forging; however, since allowances were incorporated during the design of the forging shape and die to account for this, it is judged that there will be no impact on the product's side. Due to the excess weight, a final shape was secured in which the diameter of the upper central section was slightly larger than the target. Although dimensional deficiencies directly lead to product defects, the additional allowance can be removed in subsequent processes; therefore, it is analyzed that appropriate design was achieved in terms of the die and process.
[0120] Based on this, we fabricated a disk for commercialization verification using Inconel 706 raw material. 100 of the material at room temperature per hour o 1120 at a speed of C o The temperature was raised to C and maintained for 14 hours, after which forging was performed. The sequence of the forging process was the same as the stainless steel forging performed previously.
[0121] After placing the raw material in the lower shape mold, upsetting was performed. Due to the high forming load, it was impossible to reduce it to the first height of 320 mm at the center, so rotary forging was performed using a flat die with a width of 900 mm to form it to the target height. A high forming load was required due to the influence of the material's high deformation resistance, and considering that an even higher deformation load was required due to the constraint of the mold when forming to the second target dimension, reheating was performed for approximately 180 minutes.
[0122] To reduce the forming load, forming was performed to the second target dimension using a flat die with a width of 500 mm. Although it took 15 minutes, which is slightly longer than the approximately 13 minutes required for the first forging, no process issues occurred. Additionally, for the approximately 100 kg of material added compared to the design, a diameter allowance was added to the center of the upper surface. Although jamming with the lower shape die occurred during material ejection, the ejection was completed by utilizing the pre-designed central insertion, and no abnormalities in appearance were observed in the hot and cold states compared to previous studies.
[0123] It will be obvious to those skilled in the art that the technical concept of the present invention described above is not limited to the aforementioned embodiments and attached drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical concept of the present invention. Accordingly, the scope of rights of the present invention should be determined by the claims set forth below.
Claims
Claim 1 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, comprising: a pre-forming step of pre-forming the manufacturing target by performing at least one of upsetting and cogging the manufacturing target; a manufacturing target placement step of placing the manufacturing target on a lower die for rotary forging; a first rotary forging step of forming a first region spaced apart from the center of the manufacturing target by pressing it using an upper die for rotary forging; a manufacturing target rotation step of rotating the manufacturing target by rotating the lower die for rotary forging to rotate the manufacturing target; and a second rotary forging step of forming a second region spaced apart from the center of the manufacturing target, different from the first region of the manufacturing target, by pressing it using the upper die for rotary forging. Claim 2 In claim 1, the method for manufacturing an extra-large high-strength turbine disk forging structure using rotary forging, wherein the extra-large high-strength turbine disk forging structure is composed of a one-sided stepped structure. Claim 3 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein, in claim 1, the step of rotating the manufacturing target and the second rotary forging forming step are performed repeatedly. Claim 4 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein, in claim 1, the step of rotating the manufacturing target is performed by rotating it clockwise or counterclockwise around the center of the manufacturing target. Claim 5 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein, in claim 1, the step of rotating the manufacturing target is performed by rotating the lower mold for rotary forging at an angle ranging from 1 degree to 45 degrees. Claim 6 In claim 1, the step of rotating the manufacturing target body is such that the lower mold for rotary forging is rotated at the same angle each time it is rotated, in a method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging. Claim 7 In claim 1, before or during the performance of the preforming step, the first rotary forging step, or the second rotary forging step, the manufacturing object is 950 o C to 1250 o A method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging, heating at least once to a temperature in the C range. Claim 8 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein the forged structure has a cylindrical shape with dimensions ranging from 1200 mm to 1800 mm in diameter and 300 mm to 450 mm in thickness, and has a protrusion in the center having a diameter ranging from 200 mm to 600 mm and a thickness ranging from 100 mm to 300 mm. Claim 9 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein, in claim 8, the protrusion is formed on one side or on both sides of the forged structure. Claim 10 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein the forged structure is made of stainless steel 304, stainless steel 316, or Inconel 706. Claim 11 A method for manufacturing an extra-large, high-strength turbine disk forged structure using rotary forging, comprising: a pre-forming step of pre-forming the manufacturing target by performing one or more of upsetting and cogging on the manufacturing target; a manufacturing target placement step of placing the manufacturing target on a lower die for rotary forging; a first face rotary forging step of forming a first protrusion by pressing and shaping a first face of the manufacturing target using an upper die for rotary forging; a step of placing a lower opening die for rotary forging; and a second face rotary forging step of forming a second protrusion by pressing and shaping a second face opposite to the first face of the manufacturing target using the upper die for rotary forging. Claim 12 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein the first surface rotary forging step comprises: a first rotary forging step of forming by pressing a first area spaced apart from the first central part of the first surface of the manufacturing target using the upper die for rotary forging; a first manufacturing target rotation step of rotating the manufacturing target by rotating the lower die for rotary forging; and a second rotary forging step of forming by pressing a second area spaced apart from the first central part of the manufacturing target, which is different from the first area of the manufacturing target, using the upper die for rotary forging. Claim 13 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein the step of placing the rotary forging lower opening mold comprises: removing the manufacturing object from the rotary forging lower mold; placing the rotary forging lower opening mold having an opening on the rotary forging lower mold; and placing the manufacturing object on the rotary forging lower opening mold such that a first protrusion of the manufacturing object is inserted into the opening provided in the rotary forging lower opening mold. Claim 14 A method for manufacturing an extra-large high-strength turbine disk forged structure using rotary forging, wherein the second surface rotary forging step comprises: a third rotary forging step of forming by pressing a third area spaced apart from the second central portion of the second surface of the manufacturing target using the upper die for rotary forging; a second manufacturing target rotation step of rotating the manufacturing target by rotating the lower opening die for rotary forging; and a fourth rotary forging step of forming by pressing a fourth area spaced apart from the second central portion of the manufacturing target, which is different from the third area of the manufacturing target, using the upper die for rotary forging. Claim 15 In claim 11, the method for manufacturing an extra-large high-strength turbine disk forging structure using rotary forging, wherein the extra-large high-strength turbine disk forging structure is composed of a double-sided stepped structure.