A precision forging method and forging die for a large-sized superalloy rotor mating shaft

Abstract

The present invention discloses a precision forging method and forging die for a large high-temperature alloy rotor adapter shaft, belonging to the field of high-end equipment manufacturing technology. The forging method comprises processing a cylindrical blank; heating the blank to a forging temperature; placing the blank in a lower die cavity; then controlling the upper and lower dies to close; controlling the left and right horizontal punches to move separately to form the inner cavity of the blank; controlling the left and right horizontal punches to return to their initial positions; controlling the left and right horizontal dies to move separately to complete upsetting of the prefabricated blank; shaping the inner cavity of the forging; and finally, obtaining the desired rotor adapter shaft. The forging die comprises an upper die, a lower die, a left horizontal die, a right horizontal die, a left horizontal punch, and a right horizontal punch. The present invention can meet the urgent demands of advanced heavy-duty gas turbines for product quality and manufacturing cost, and has significant economic and social benefits.

Description

Technical Field

[0001] The present invention belongs to the field of high-end equipment manufacturing, and in particular to the field of forging technology, and specifically to a precision forging method and a forging die for a large high-temperature alloy rotor adapter shaft. Background Art

[0002] The rotor adapter shaft is one of the most critical load-bearing components in heavy-duty gas turbines. Its characteristic shape is an axisymmetric body of revolution, consisting of a cylindrical main body with a through hole and a flange at each end. It primarily serves as a connection to the rotating shaft and must withstand high temperatures, high pressures, and transmission torque for extended periods. Its service life is extremely harsh, placing high demands on the rotor adapter shaft's performance in terms of high-temperature tensile strength, high-temperature durability, high-temperature creep, and high-cycle fatigue. Therefore, in addition to selecting expensive high-temperature alloys, the rotor adapter shaft also places stringent demands on its manufacturing process.

[0003] The rotor adapter shaft forgings for heavy-duty gas turbines generally weigh more than 1 ton. Using traditional ordinary die forging technology, due to the need for demolding, it is necessary to design and add a process block between the two flanges. This results in a great waste of expensive metal materials and high production costs. In addition, the streamlines of the cylindrical main body of the rotor adapter shaft die forging are cut off and exposed, affecting the comprehensive mechanical properties of the parts, such as service fatigue.

[0004] Multi-directional die forging is currently an important method for manufacturing hollow, special-shaped parts. However, using multi-directional die forging for large high-temperature alloy rotor adapter shaft forgings presents significant challenges: high-temperature alloy materials have extremely high deformation resistance. Using conventional multi-directional die forging technology, the horizontal forging load would exceed 20,000 tons, and existing equipment cannot provide such high forging capacity. High-temperature alloy materials also have a narrow deformation process window. If the forging deformation in any one pass is less than 30%, the risk of the forging's microstructure and performance failing will increase dramatically, leading to scrap. Therefore, it is impossible to achieve rotor adapter shaft forging through multi-pass multi-directional die forging.

[0005] Therefore, how to reduce the forging forming load to achieve precision forging of the high-temperature alloy rotor adapter shaft has become a technical problem that those skilled in the art continue to solve. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to solve the problems of high material consumption and incomplete streamlines in traditional production processes, and to provide a precision forging method and forging die for a large high-temperature alloy rotor adapter shaft, which can meet the urgent needs of advanced heavy-duty gas turbines in terms of product quality and manufacturing costs, and has great economic and social benefits.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a method for precision forging a large high-temperature alloy rotor adapter shaft, characterized in that it includes the following steps:

[0008] Step 1: Process the cylindrical blank according to the outer dimensions of the forging;

[0009] Step 2: Heat the blank to the forging temperature, then take out the blank, cover the surface of the blank with glass powder binder, and then cover it with insulation cotton, and heat the blank again for a certain period of time;

[0010] Step 3: Place the heated blank in the cavity of the lower mold, then control the upper mold to move downward, and continue to move downward after contacting the blank until the upper mold and the lower mold are closed, completing the downward pressing action;

[0011] Step 4: The upper die maintains a downward pressure state, and then controls the left horizontal punch to move to the right to contact the blank. At the same time, controls the right horizontal punch to move to the left to contact the blank. Continue to simultaneously control the left and right horizontal punches to move to the designated target positions, respectively, to form the inner cavity of the blank.

[0012] Step 5: Control the left and right horizontal punches to perform return motion respectively until they return to their initial positions, thereby completing the preparation of the preform with the inner cavity;

[0013] Step 6: Control the left horizontal die to move rightward until it contacts the preform, and at the same time, control the right horizontal die to move leftward until it contacts the preform. Then, simultaneously control the left and right horizontal dies to move to designated target positions, respectively, to complete the upsetting of the preform.

[0014] Step 7: Control the left horizontal die and the right horizontal die to make a return motion respectively, and stop after reaching the designated position. Then control the left horizontal punch to move to the right again and enter the inner hole of the blank. At the same time, control the right horizontal punch to move to the left and enter the inner hole of the blank until the left and right horizontal punches move to the designated target positions respectively, completing the shaping of the inner hole of the forging.

[0015] Step 8: Finally, control the left horizontal punch, the right horizontal punch, the left horizontal die, the right horizontal die and the upper die to return to their initial positions to obtain the required rotor adapter shaft.

[0016] Furthermore, the diameter of the cylindrical blank is 0.1-5 mm smaller than the maximum diameter of the inner hole formed after the upper mold and the lower mold are closed.

[0017] Furthermore, the thickness of the thermal insulation cotton covering the surface of the cylindrical blank is 5 to 10 mm.

[0018] Furthermore, in step four, after the left and right horizontal punches move to the designated target positions, the distance between the left and right horizontal punches is 40-60 mm, so that the thickness of the skin between the left inner cavity and the right inner cavity of the blank is 40-60 mm.

[0019] Furthermore, in step 4, the forging load of the blank is 2900 tons.

[0020] Furthermore, in step six, the forging load of upsetting is 5000 tons.

[0021] Furthermore, in step seven, the forging load for shaping the inner cavity is 800 tons.

[0022] A precision forging die for a large high-temperature alloy rotor adapter shaft, characterized in that: it includes an upper die, a lower die, a left horizontal die, a right horizontal die, a left horizontal punch and a right horizontal punch; the shape of the inner hole formed after the upper die and the lower die are combined matches the side shape of the rotor adapter shaft to be processed; the left horizontal die and the right horizontal die are respectively arranged at both ends of the lower die, and their axis lines coincide with the axis line of the inner hole formed after the upper die and the lower die are combined, and can slide in the inner hole formed after the upper die and the lower die are combined; through holes are opened on the left horizontal die and the right horizontal die respectively along their axis lines, and the stamping ends of the left horizontal punch and the right horizontal punch respectively pass through the left horizontal die and the right horizontal die and extend into the lower die, and are respectively connected to the left horizontal die and the right horizontal die in a sliding manner.

[0023] Furthermore, the end faces of the left horizontal mold and the right horizontal mold extending into the lower mold are both stepped surfaces, wherein the inner ring surface close to the inner side of the end faces of the left horizontal mold and the right horizontal mold protrudes from the outer ring surface close to the outer side, and the thickness of the protruding part is 10~20mm, the area of the inner ring surface is 0.8~1.2 times the area of the outer ring surface, and the connection between the inner ring surface and the outer ring surface is chamfered.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1) By adopting the method of multiple partitioned local loading, the traditional large-contact-area extrusion deformation in the horizontal direction of multi-directional die forging is transformed into extrusion punching + ring upsetting + punching shaping with a small contact area. This can significantly reduce the forming load of large high-temperature alloy rotor adapter shaft forgings during multi-directional die forging by more than 60%.

[0026] 2) The present invention adopts a single-fire precision forging process, which avoids the problem of streamline being cut off at the cylindrical body of the rotor adapter shaft die forging. The maximum forming load is only 6,000 tons, the number of forging fires is reduced by 75%, the forming load is reduced by 87.5%, material consumption can be reduced by more than 30%, and machining time can be reduced by more than 20%. The material cost alone can save 141,000 yuan per piece, which has significant economic benefits.

[0027] 3) It can realize the complete forming of the overall characteristic structure of the rotor adapter shaft without adding auxiliary features such as process blocks and flash, realizing the full streamline forging of metal, improving the comprehensive mechanical properties of the product, ensuring product quality, and high production efficiency, which helps to meet the service requirements of advanced heavy equipment for the safety and reliability of key components. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A forging flow chart for machining a rotor adapter shaft forging according to the present invention.

[0029] Figure 2 It is a structural schematic diagram of the forging die in the present invention.

[0030] Figure 3 The figure is a schematic structural diagram of a rotor adapter shaft forging for a heavy-duty gas turbine according to an embodiment of the present invention.

[0031] In the figure: 1—cylindrical blank, 2—lower die, 3—upper die, 4—left horizontal punch, 5—right horizontal punch, 6—left horizontal die, 7—right horizontal die. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not require further definition or explanation in subsequent figures. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the figures, or the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and are not to be construed as indicating or implying relative importance. Furthermore, terms such as "horizontal" and "vertical" do not imply that a component must be absolutely horizontal or overhanging, but rather may be slightly tilted. For example, "horizontal" simply refers to a direction that is more horizontal than "vertical," and does not imply that the structure must be completely horizontal, but rather may be slightly tilted. In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0035] Example: See Figure 1 A method for precision forging a large high-temperature alloy rotor adapter shaft comprises the following steps:

[0036] Step 1: Process a cylindrical blank 1 according to the outer dimensions of the forging (rotor adapter shaft to be processed); at the same time, select or process a corresponding combination die according to the forging size.

[0037] Step 2: Heat the blank to the forging temperature, then take out the blank, cover the surface of the blank with glass powder binder, and then cover it with insulation cotton, and heat and keep the blank warm again for a certain period of time; wherein, the thickness of the insulation cotton covering the surface of the cylindrical blank 1 is 5~10mm; thereby improving the insulation effect.

[0038] Step 3: Place the heated blank in the cavity of the lower mold 2, then control the upper mold 3 to move downward, and continue to move downward after contacting the blank until the upper mold and the lower mold are closed, completing the downward pressing action. The diameter of the cylindrical blank 1 is smaller than the maximum diameter of the inner hole formed by the upper mold 3 and the lower mold 2 after closing, which is 0.1-5mm. In this way, the diameter of the cylindrical blank 1 is slightly smaller than the diameter of the cylindrical body of the sleeve forging. When the upper mold and the lower mold are closed to extrude the cylindrical blank 1, no flash will be formed at the die mouth of the combined mold; thereby effectively reducing the processing steps, ensuring the processing quality, and improving the processing efficiency.

[0039] Step 4: The upper die 3 remains in a downward pressure state, and then the left horizontal punch 4 and the right horizontal punch 5 join the action, controlling the left horizontal punch 4 to move to the right to contact the blank, while controlling the right horizontal punch 5 to move to the left to contact the blank; continue to simultaneously control the left and right horizontal punches 5 to move to the designated target positions, forming the inner cavity of the blank. That is, a cylindrical groove is formed at each end of the cylindrical blank 1, and the gap between the two cylindrical grooves forms a skin; by controlling the stroke of the horizontal punch, the thickness of the formed skin can be accurately controlled, avoiding secondary processing, thereby helping to improve the processing accuracy and efficiency of the entire forging. Among them, the forging load of the blank is 2900 tons. As an embodiment, after the left and right horizontal punches 5 move to the designated target positions, the spacing between the left and right horizontal punches 5 is 40-60 mm, so that the thickness of the skin between the inner cavity on the left and the inner cavity on the right of the blank is 40-60 mm.

[0040] Step 5: Control the left and right horizontal punches 5 to perform return motion respectively until they return to their initial positions, thereby completing the preparation of the preform with the inner cavity.

[0041] Step 6: The left and right horizontal dies 6 and 7 are activated, controlling the left horizontal die 6 to move rightward until it contacts the preform. Simultaneously, the right horizontal die 7 is controlled to move leftward until it contacts the preform. Then, the left and right horizontal dies 6 and 7 are simultaneously controlled to move to their designated target positions, completing the upsetting of the preform. The upsetting forging load is 5,000 tons.

[0042] Step 7: Control the left horizontal die 6 and the right horizontal die 7 to make a return motion respectively, and stop after reaching the designated position; then the left horizontal punch 4 and the right horizontal punch 5 join the action again, control the left horizontal punch 4 to move to the right and enter the inner hole of the blank, and at the same time, control the right horizontal punch 5 to move to the left and enter the inner hole of the blank, until the left and right horizontal punches 5 move to the designated target positions respectively, completing the shaping of the inner hole of the forging; wherein, the forging load of the inner hole shaping is 800 tons. When shaping the inner hole, the side wall of the forging is always under the constraints of the upper and lower dies 2, so it will not deform; at the same time, the overall deformation of the inner hole shaping is very small, and the deformation is mainly concentrated in the inner hole of the forging, so the deformation of the end face of the forging can be ignored.

[0043] Step 8: Finally, control the left horizontal punch 4, the right horizontal punch 5, the left horizontal die 6, the right horizontal die 7 and the upper die 3 to return to their initial positions to obtain the required rotor adapter shaft.

[0044] See also Figure 2 The present invention also discloses a precision forging die for a large high-temperature alloy rotor adapter shaft, comprising an upper die 3, a lower die 2, a left horizontal die 6, a right horizontal die 7, a left horizontal punch 4, and a right horizontal punch 5. The shape of the inner hole formed after the upper die 3 and the lower die 2 are combined matches the side shape of the rotor adapter shaft to be processed, and the inner hole formed after the combination is a horizontal hole. The left horizontal die 6 and the right horizontal die 7 are respectively arranged at both ends of the lower die 2, and their axis coincides with the axis of the inner hole formed after the upper die 3 and the lower die 2 are combined, and can slide in the inner hole formed after the upper die 3 and the lower die 2 are combined. On the left horizontal die 6 and the right horizontal die 7, through holes are respectively opened along their axis, and the punching ends of the left horizontal punch 4 and the right horizontal punch 5 respectively pass through the left horizontal die 6 and the right horizontal die 7 and extend into the lower die 2, and are respectively connected to the left horizontal die 6 and the right horizontal die 7 in a sliding manner. Among them, the diameter of the horizontal punch is consistent with the inner diameter of the rotor adapter shaft forging, with a draft angle of 1~2°; the inner diameter of the horizontal die is 5~10mm larger than the diameter of the horizontal punch; the outer diameter of the horizontal die is 20~30mm smaller than the outer diameter of the rotor adapter shaft forging flange.

[0045] During implementation, the end faces of the left and right horizontal dies 6 and 7, extending into the lower die 2, are both stepped. The inner ring surface of each of the left and right horizontal dies 6 and 7 protrudes from the outer ring surface, with the thickness of the protruding portion ranging from 10 to 20 mm. The inner ring surface area is 0.8 to 1.2 times that of the outer ring surface, and the transition between the inner and outer ring surfaces is rounded. This creates a step difference between the forging end faces of the left and right horizontal dies 6 and 7, resulting in a time delay between the contact between the horizontal dies and the blank during ring upsetting deformation. The inner ring surface contacts the outer ring surface first, and then the outer ring surface contacts the blank as deformation progresses. This effectively slows the rate of increase in deformation load during ring upsetting, further reducing the horizontal forging load. In order to improve the stability and service life of the entire forging die and reduce costs, the horizontal punch and the horizontal die are made of different materials; preferably, the material of the horizontal punch is a high-temperature alloy material with excellent high-temperature performance, such as GH4169; the material of the horizontal die is an ordinary die steel material, such as 5CrMnMo.

[0046] During the forging process, the billet is placed horizontally in the lower die 2, and the upper die 3, driven by a hydraulic cylinder, is used to apply force to the top of the billet. The left horizontal die 6, right horizontal die 7, left horizontal punch 4, and right horizontal punch 5 are each driven by a hydraulic cylinder. The ends of the left horizontal punch 4 and left horizontal die 6 can respectively extend into the left opening of the die body and be used to apply force to the left side of the billet. The ends of the right horizontal punch 5 and right horizontal die 7 can respectively extend into the right opening of the die body and be used to apply force to the right side of the billet.

[0047] This solution adopts the method of multiple partitioned local loading to transform the traditional large-contact-area extrusion deformation in the horizontal direction of multi-directional die forging into extrusion punching + ring upsetting + punching shaping with a small contact area, which can significantly reduce the forming load of large high-temperature alloy rotor adapter shaft forgings during multi-directional die forging by more than 60%.

[0048] At the same time, the use of a single-fire precision forging process avoids the problem of streamlines being cut off at the cylindrical body of the rotor adapter shaft die forging. The maximum forming load is only 6,000 tons, the number of forging fires is reduced by 75%, the forming load is reduced by 87.5%, material consumption can be reduced by more than 30%, and machining time can be reduced by more than 20%. The material cost alone can save 141,000 yuan per piece, which has significant economic benefits. Ultimately, the complete forming of the overall characteristic structure of the rotor adapter shaft can be achieved, without the need to add auxiliary features such as process blocks and flash, achieving full metal streamline forging, improving the comprehensive mechanical properties of the product, ensuring product quality, and high production efficiency. It helps to meet the service requirements of advanced heavy equipment for the safety and reliability of key components.

[0049] See also Figure 3The following describes the manufacturing method of the present invention in detail, using a rotor adapter shaft forging for a heavy-duty combustion turbine as an example. The forging has outer dimensions of 646 (outer diameter) x 250 (inner diameter) x 475 (height) mm, with both left and right flange widths of 116 mm. The outer diameter of the cylindrical forging is 496 mm, and the forging weighs 905 kg. The specific manufacturing steps are as follows:

[0050] Step 1: Design the die and cylindrical blank based on the forging dimensions. The horizontal punch has a diameter of 250mm and a 1° draft angle. The horizontal die has an outer diameter of 620mm and an inner diameter of 255mm. The contact end with the blank (forging end) is stepped with a 15mm height difference. The step transition has a 10mm radius. The blank dimensions are 490mm in diameter and 610mm in length.

[0051] Step 2: Heat the blank to the forging temperature of 1010℃, then take out the blank, cover the surface with glass powder binder and then wrap it with 10mm thick insulation cotton, return the blank to the furnace and heat it for 90 minutes, then place the heated blank in the lower mold cavity.

[0052] Step 3: The upper die moves downward and contacts the blank to complete the downward pressing action. This step is similar to the conventional forging deformation process, but the diameter of the cylindrical blank is 0~5mm smaller than the diameter of the cylindrical body of the sleeve forging. Therefore, after the upper die and the lower die are closed, no flash will be formed at the horizontal die opening.

[0053] Step 4: The upper die maintains pressure (downward pressure state) and stops, the left horizontal punch and the right horizontal punch join the action, the left horizontal punch moves to the right and contacts the blank, at the same time, the right horizontal punch moves to the left and contacts the blank, the left horizontal punch and the right horizontal punch move 270mm to the target position respectively, and extrude and punch the blank.

[0054] Step 5: The left horizontal punch and the right horizontal punch make a return motion respectively and stop after reaching the designated position. At this time, the prefabricated part with a skin thickness of 60 mm is completed.

[0055] Step 6: The left horizontal die and the right horizontal die join the action. The left horizontal die moves to the right and contacts the preform. At the same time, the right horizontal die moves to the left and contacts the preform. The left and right horizontal dies move 107 mm to the target position respectively, completing the ring upsetting of the preform to obtain the preformed forging.

[0056] Step 7: The left horizontal mold and the right horizontal mold make a return motion respectively, and stop when they reach the designated position. The left horizontal punch and the right horizontal punch join the action. The left horizontal punch moves to the right and contacts the inner hole of the preform. At the same time, the right horizontal punch moves to the left and contacts the inner hole of the preform. The left and right horizontal punches move 270mm to the target position respectively to shape the inner hole of the preform.

[0057] Step 8: Finally, control the left horizontal punch, the right horizontal punch, the left horizontal die, the right horizontal die and the upper die to return to their initial positions to obtain the required precision rotor adapter shaft forging.

[0058] If the traditional die forging method is used, the weight of the forging is 1255Kg, the weight of the feed material is 1380Kg, and it requires 2 rounds of blank making, 1 round of pre-forging, and 1 round of final forging. After die forging, the flash needs to be removed. However, by adopting the technology of the present invention, the weight of the forging can be reduced from 1255Kg to 905Kg, a reduction of 27.9%; the feed weight is reduced from 1380Kg to 910Kg, a reduction of 34.1%; the number of forging rounds is reduced from 4 rounds to 1 round, a reduction of 75%; after die forging, only burrs need to be polished, and there is no need to remove flash; the material cost of a single piece can be saved by 141,000 yuan. Based on the annual demand of 50 gas turbines, 7.05 million yuan can be saved each year, which has great economic benefits. From the above data, it can be seen that compared with the existing technology, this solution has significant improvements, and has better processing accuracy, processing efficiency, and cost control.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for precision forging a large high-temperature alloy rotor adapter shaft, characterized by: A forging die is used, which includes an upper die, a lower die, a left horizontal die, a right horizontal die, a left horizontal punch, and a right horizontal punch; the shape of the inner hole formed after the upper die and the lower die are combined matches the side shape of the rotor adapter shaft to be processed; the left horizontal die and the right horizontal die are respectively arranged at both ends of the lower die, and their axis centers coincide with the axis center lines of the inner hole formed after the upper die and the lower die are combined, and can slide in the inner hole formed after the upper die and the lower die are combined; through holes are respectively opened on the left horizontal die and the right horizontal die along their axis centers, and the punching ends of the left horizontal punch and the right horizontal punch respectively pass through the left horizontal die and the right horizontal die and extend into the lower die, and are respectively connected to the left horizontal die and the right horizontal die in a sliding manner; The specific steps include: Step 1: Process the cylindrical blank according to the outer dimensions of the forging; Step 2: Heat the blank to the forging temperature, then take out the blank, cover the surface of the blank with glass powder binder, and then cover it with insulation cotton, and heat the blank again for a certain period of time; Step 3: Place the heated blank in the cavity of the lower mold, then control the upper mold to move downward, and continue to move downward after contacting the blank until the upper mold and the lower mold are closed, completing the downward pressing action; Step 4: The upper die maintains a downward pressure state, and then controls the left horizontal punch to move to the right to contact the blank. At the same time, controls the right horizontal punch to move to the left to contact the blank. Continue to simultaneously control the left and right horizontal punches to move to the designated target positions, respectively, to form the inner cavity of the blank. Step 5: Control the left and right horizontal punches to perform return motion respectively until they return to their initial positions, thereby completing the preparation of the preform with the inner cavity; Step 6: Control the left horizontal die to move rightward until it contacts the preform, and at the same time, control the right horizontal die to move leftward until it contacts the preform. Then, simultaneously control the left and right horizontal dies to move to designated target positions, respectively, to complete the upsetting of the preform. Step 7: Control the left horizontal die and the right horizontal die to make a return motion respectively, and stop after reaching the designated position. Then control the left horizontal punch to move to the right again and enter the inner hole of the blank. At the same time, control the right horizontal punch to move to the left and enter the inner hole of the blank until the left and right horizontal punches move to the designated target positions respectively, completing the shaping of the inner hole of the forging. Step 8: Finally, control the left horizontal punch, the right horizontal punch, the left horizontal die, the right horizontal die and the upper die to return to their initial positions to obtain the required rotor adapter shaft.

2. The method for precision forging a large high-temperature alloy rotor adapter shaft according to claim 1, characterized in that: The diameter of the cylindrical blank is 0.1-5 mm smaller than the maximum diameter of the inner hole formed after the upper mold and the lower mold are closed.

3. The method for precision forging a large high-temperature alloy rotor adapter shaft according to claim 1, characterized in that: The thickness of the thermal insulation cotton covering the surface of the cylindrical blank is 5~10mm.

4. The method for precision forging a large high-temperature alloy rotor adapter shaft according to claim 1, characterized in that: In step 4, after the left and right horizontal punches move to the designated target positions, the distance between the left and right horizontal punches is 40-60 mm, so that the thickness of the skin between the left inner cavity and the right inner cavity of the blank is 40-60 mm.

5. The method for precision forging a large high-temperature alloy rotor adapter shaft according to claim 1, characterized in that: In step 4, the forging load of the billet is 2900 tons.

6. The method for precision forging a large high-temperature alloy rotor adapter shaft according to claim 1, characterized in that: In step six, the forging load for upsetting is 5000 tons.

7. The method for precision forging a large high-temperature alloy rotor adapter shaft according to claim 1, characterized in that: In step seven, the forging load for shaping the inner cavity is 800 tons.

8. The method for precision forging a large high-temperature alloy rotor adapter shaft according to claim 1, characterized in that: The end faces of the left horizontal mold and the right horizontal mold at one end extending into the lower mold are both stepped surfaces, wherein the inner ring surface close to the inner side of the end faces of the left horizontal mold and the right horizontal mold protrudes from the outer ring surface close to the outer side, and the thickness of the protruding part is 10~20mm, the area of the inner ring surface is 0.8~1.2 times the area of the outer ring surface, and the connection between the inner ring surface and the outer ring surface is chamfered.

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