Large turbine disc forge piece manufacturing device and method

Abstract

The invention relates to the technical field of difficult-to-deform high-temperature alloy forging, in particular to a large turbine disc forge piece manufacturing device and method. The device comprises N split type forging die sets and N punches in one-to-one correspondence, N is larger than or equal to 3, and each split type forging die set comprises an anvil block, a left side die, a right side die and a die sleeve; the left side mold and the right side mold are half revolved bodies and are combined to form an inner cavity matched with the appearance of a cast ingot or a forged piece; the anvil block is of a rotary body structure, and the upper end of the anvil block is provided with positioning holes matched with the lower ends of the left side mold and the right side mold. The die sleeve sleeves the peripheries of the left and right side dies and is in conical surface positioning fit; the punches are matched with the anvil blocks and used for applying forging pressure to cast ingots or forgings in the die, and the contact ends of the punches used for adjacent heating number forging and the anvil blocks are alternately arranged in a concave-flat mode. According to the method, the phenomena of upsetting instability and surface cracking are eliminated, the material utilization rate is increased, the mass production quality consistency is guaranteed, and the method is suitable for preparing the large-scale difficult-to-deform high-temperature alloy turbine disc forgings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of difficult-to-deform superalloy forging, in particular to a large turbine disc forging preparation device and method. BACKGROUND

[0002] Turbine disc is the core component of aero-engine, gas turbine and other power equipment, and its working environment is harsh, which needs to withstand high temperature, high pressure and complex alternating load. Therefore, the high temperature strength, plasticity, toughness and microstructure uniformity of the material are extremely high. Difficult-to-deform superalloy has excellent high temperature performance due to the addition of a large amount of alloying elements, and becomes the preferred material for manufacturing large turbine discs.

[0003] Casting ingot breakdown is the first process of hot working forging of deformed superalloy turbine disc, and its core purposes are two: one is to break the as-cast dendritic structure, obtain uniform and fine structure meeting the grain size requirement, and improve the plasticity of the material; the other is to change the geometry of the casting ingot, laying a foundation for subsequent processing. However, for some difficult-to-deform superalloys, due to the high content of alloying elements, the diameter of the casting ingot prepared by electroslag remelting continuous directional solidification process is usually less than 350 mm, and in order to avoid element segregation during solidification, the chemical composition and microstructure uniformity of the casting ingot need to be strictly controlled.

[0004] In the prior art, for high-temperature alloy casting ingots with a diameter of less than 350 mm, the length of the casting ingot is usually controlled to be less than 2.5 times of the diameter to ensure the forging quality. This is because when the ratio of the height of the casting ingot to the diameter exceeds 2.5, instability phenomenon is prone to occur during the upsetting process, which leads to cracking on the surface of the casting ingot, and the crystal structure of the material cannot be refined to the ideal effect. As shown in FIG. 1, using a traditional forging equipment, the punch 2 is a flat bottom punch, and the anvil 1 is a flat top anvil. The anvil 1 and the punch 2 will form a forged casting ingot after forging the cylindrical casting ingot with a diameter less than 350 mm, which includes a full-section grain refinement sufficient zone 301, an upper insufficient grain refinement zone 302 and a lower insufficient grain refinement zone 303, and the full-section grain size cannot meet the standard. Figure 1

[0005] To solve the above problems, the prior art usually adopts upsetting and drawing combined forging process, but for large turbine disc forgings, the realization of the drawing process is extremely difficult, not only the process flow is complex, but also it will lead to increased material loss, reduced production efficiency, and it is difficult to ensure the consistency of product quality in batch production. Therefore, there is an urgent need for a new technical solution to break through the constraints of the existing casting and forging process, and to realize the efficient and high-quality preparation of difficult-to-deform superalloy large turbine disc forgings. SUMMARY

[0006] ​To address the aforementioned problems, the present invention aims to provide a large turbine disk forging preparation apparatus and method, thereby solving the problems in the prior art such as upsetting instability, surface cracking, and insufficient crystal structure refinement caused by the high-diameter ratio limitation of difficult-to-deform high-temperature alloy ingots, as well as the complex preparation process, low material utilization, and unstable batch production quality of large turbine disk forgings.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The present invention provides a large turbine disk forging preparation device, including N sets of split forging die groups and N corresponding punches, where N≥3. Each set of the split forging die group includes an anvil, a left die, a right die and a die sleeve.

[0009] The left mold and the right mold are half of a rotating body with the same structure. The left mold and the right mold are combined to form a mold with a complete rotating body structure, and the combined mold forms an inner cavity that is adapted to the shape of the ingot or forging.

[0010] The anvil is a rotating structure, and its upper end is provided with positioning holes that are adapted to the lower ends of the left and right molds;

[0011] The mold sleeve is fitted around the outer periphery of the merged left and right molds, and the upper end of the mold sleeve is in a conical positioning fit with the left and right molds;

[0012] The punch cooperates with the anvil to apply forging pressure to the ingot or forging in the mold, and the contact ends of the punch and the anvil used in adjacent forging operations are alternately arranged with concave and flat shapes.

[0013] The inner cavity formed by the merging of the left mold and the right mold includes a small-diameter hole segment and a large-diameter hole segment. The diameter of the small-diameter hole segment is adapted to the outer diameter of the small-diameter segment of the corresponding fire-cast ingot or forging. The diameter of the large-diameter hole segment is larger than the outer diameter of the corresponding segment of the corresponding fire-cast ingot or forging.

[0014] The height of the large-diameter hole section satisfies the following condition: the height of the non-contact portion with the corresponding ingot or forging is less than 2.5 times the initial ingot diameter.

[0015] The punch used in the first forging is a dome punch, whose dome is used to contact the upper end face of the initial ingot; the punch used in the second forging is a flat-bottom punch, whose flat end is used to contact the upper recess of the corresponding forging.

[0016] The anvil used in the first forging is a domed anvil, the domed end of which is used to contact the lower end face of the initial ingot; the anvil used in the second forging is a flat anvil, the flat end of which is used to contact the lower recess of the corresponding forging.

[0017] The split forging die set used in the Nth forging is a closed die structure. After the left die, right die, anvil and punch are matched, they form a fully enclosed constraint on the Nth forging, realizing flash-free forging.

[0018] The inner cavity shape of the mold is determined by simulating the deformation region distribution of the upsetting process of the forging workpiece to ensure that the grain size of the forging workpiece is uniform and controllable.

[0019] The initial ingot is a cylindrical alloy ingot with a height-to-diameter ratio greater than 2.5 and a diameter less than 350 mm.

[0020] The initial ingot is forged through N sets of split forging dies, and its diameter gradually increases.

[0021] The forgings corresponding to the split forging die set used in the Nth forging are stepped forging discs. The forgings have three forging radii and their microstructure is a uniform fine-grained microstructure with an average grain size of not less than ASTM 8.0.

[0022] The positioning hole on the anvil is a frustum hole. The lower ends of the left mold and the right mold are provided with a semi-frustum. The semi-frustum fits into the frustum hole of the anvil to form a mold taper friction self-locking structure, which is used to ensure the stability of the mold after mold closing.

[0023] Another aspect of the present invention provides a method for preparing a large turbine disk forging using the device described above, comprising the following steps:

[0024] Step S1: Prepare N sets of split forging die sets and N corresponding punches, where N is greater than or equal to 3;

[0025] Step S2: Heat N sets of split forging die sets and N corresponding punches to a predetermined temperature of 480°C to 490°C and hold at that temperature for 4 to 4.5 hours.

[0026] Step S3: Hold the initial ingot at 1000-1050℃ for 18-20 hours;

[0027] Step S4: Place the initial ingot after heat preservation into the first set of split forging molds, and use the corresponding punch to perform local upsetting and forging at a speed of 25mm / s~30mm / s until the outer circumference of the ingot matches the inner circumference of the mold to obtain a hot forging.

[0028] Step S5: Iteratively execute steps S3 and S4, replace the subsequent split forging die set for N-stage forging. In adjacent forging stages, the upper and lower ends of the forging and the die switch between concave and flat surfaces. The height of the large-diameter hole section of each die set satisfies the requirement that the height of the non-contact part of the corresponding forging is less than 2.5 times the initial ingot diameter, and finally obtains a stepped forging disc-shaped N-stage forging.

[0029] The present invention has the following beneficial effects and advantages:

[0030] 1. Effectively solves the problem of instability during upsetting of difficult-to-deform high-temperature alloy ingots with a height-to-diameter ratio exceeding 2.5. This invention avoids bulging and surface cracking during the upsetting process of ingots by using a dedicated split forging die set, switching between concave and flat contact states at the upper and lower ends of adjacent forging passes, and precise design of the die cavity shape, thereby obtaining billets with high-quality surface finish.

[0031] 2. Achieving sufficient refinement of the as-cast microstructure. The mold cavity shape of this invention is designed based on the deformation region distribution simulated in a simulation. Combined with N-stage upsetting, it can fully break up the as-cast dendritic structure, promote dynamic recrystallization, and enable the forging to obtain a uniform fine-grained microstructure with an average grain size of not less than ASTM 8.0, which meets the requirements for the use of large turbine disks.

[0032] 3. Simplified process and improved production efficiency. This invention eliminates the need for traditional upsetting and drawing processes. Large turbine disk forgings can be prepared through N-stage progressive upsetting forging. The process is simple, easy to operate, and the deformation can be accurately calculated, ensuring the consistency and stability of batch production quality.

[0033] 4. Improve material utilization and reduce production costs. This invention adopts a flash-free triaxial compressive stress forging method. The height of the large-diameter semi-hole of the die is greater than the length of the corresponding ingot or forging, which avoids material waste caused by flash, reduces subsequent machining allowance, improves material utilization, and saves resources of difficult-to-deform high-temperature alloys.

[0034] 5. The mold is highly adaptable and requires no additional lubrication or sheathing. The split mold of this invention eliminates the mold-forging locking problem caused by thermodynamic and engineering mechanics factors in traditional tubular internal molds. It eliminates the need for glass lubricant powder or forging soft sheathing, avoiding damage to the crystal structure of the forging surface caused by lubricant powder or sheathing. At the same time, it eliminates the need to design draft angles, simplifying the mold processing technology.

[0035] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a cross-sectional schematic diagram of a traditional forging equipment;

[0039] Figure 2 This is a three-dimensional schematic diagram of the first-stage split forging die assembly in this invention;

[0040] Figure 3 This is a schematic axial cross-sectional view of the first-stage split forging die assembly in this invention;

[0041] Figure 4 for Figure 3 Enlarged view of a portion of point A in the middle;

[0042] Figure 5 for Figure 3 Enlarged view of a portion of point B in the middle;

[0043] Figure 6 This is a schematic diagram of the axial cross-section of the second-stage split forging die assembly in this invention;

[0044] Figure 7 for Figure 6 Enlarged view of a portion of point C in the middle;

[0045] Figure 8 This is a cross-sectional schematic diagram of the Nth split-type forging die assembly in this invention.

[0046] In the diagram: 1. Anvil; 2. Punch; 301. Sufficiently refined crystallization zone; 302. Upper insufficiently refined crystallization zone; 303. Lower insufficiently refined crystallization zone; 4. First anvil; 401. First anvil's frustum-shaped hole; 402. First anvil's plane; 403. First anvil's dome; 5. First left-side mold; 501. Small-diameter half-hole of the first left-side mold; 502. Large-diameter half-hole of the first left-side mold; 503. Semi-frustum of the first left-side mold; 504. Semi-conical surface of the first left-side mold; 6. First right-side mold; 601. Small-diameter half-hole of the first right-side mold; 602. First... 603. Large-diameter half-hole of the right mold; 604. Semi-circular frustum of the first right mold; 605. Semi-conical surface of the first right mold; 7. First mold sleeve; 8. First punch; 806. Dome of the first punch; 9. Initial ingot; 10. Second anvil; 11. Second punch; 12. First-fired forging; 1207. Lower concave surface of the second-fired forging; 1208. Upper concave surface of the second-fired forging; 13. Second left mold; 14. Second right mold; 15. Nth anvil; 16. Nth left mold; 17. Nth right mold; 18. Nth-fired forging; 19. Nth punch; 20. Nth mold sleeve. Detailed Implementation

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0049] An embodiment of the present invention provides a large turbine disk forging preparation device, including N sets of split forging die groups and N corresponding punches, where N≥3. Each set of split forging die groups includes an anvil, a left die, a right die, and a die sleeve. The left die and the right die are half-rotation bodies with the same structure. After the left die and the right die are combined, they form a complete rotation body structure and an inner cavity adapted to the shape of the ingot or forging. The anvil is a rotation body structure and has a positioning hole at its upper end that matches the lower end of the left die and the right die. The die sleeve is fitted around the outer periphery of the combined left die and the right die, and the upper end of the die sleeve is positioned with the left die and the right die by a conical surface. The punches cooperate with the anvil to apply forging pressure to the ingot or forging inside the die, and the contact ends of the punches and the anvil used in adjacent forging passes are alternately arranged with concave and flat shapes.

[0050] Furthermore, the inner cavity formed by merging the left and right molds includes a small-diameter hole segment and a large-diameter hole segment. The diameter of the small-diameter hole segment matches the outer diameter of the small-diameter segment of the corresponding hot-fired ingot or forging, while the diameter of the large-diameter hole segment is larger than the outer diameter of the corresponding segment of the corresponding hot-fired ingot or forging. The shape of the mold's inner cavity is determined by simulating the deformation region distribution during the upsetting process of the forging to ensure uniform and controllable grain size of the forging.

[0051] Specifically, the height of the large-diameter hole section satisfies the following: the height of the non-contact part with the corresponding fire-cast ingot or forging is less than 2.5 times the diameter of the initial ingot; the diameter of the initial ingot gradually increases after being forged by N sets of split forging die groups.

[0052] Furthermore, the positioning hole on the anvil is a frustum hole, and the lower ends of the left and right molds are provided with semi-frustums. The semi-frustums fit into the frustum holes of the anvil to form a mold taper friction self-locking structure, which is used to ensure the stability of the mold after mold closing.

[0053] See Figures 2 to 5As shown in the embodiment of the present invention, the split forging die assembly used in the first forging includes a first anvil 4, a first left-side die 5, a first right-side die 6, a first die sleeve 7, and a first punch 8. The first punch 8 has a first punch dome 801, which is used to contact the upper end face of the initial ingot 9. The first anvil 4 has a first anvil frustum hole 401, and a first anvil dome 403 is provided at the center of the first anvil plane 402 at the bottom of the first anvil frustum hole 401. The first anvil dome 403 is used to contact the lower end face of the initial ingot. The first left-side die 5 and the first right-side die 6 are identical half-rotor bodies. The inner side of the first left-side die 5 has a first left-side die small-diameter half-hole 501 and a first left-side die large-diameter half-hole 502 from top to bottom. The lower end of the outer circumference of the first left-side die 5 has a first left-side die semi-frustum 503, and the upper end has a first left-side die semi-conical surface 504. The inner side of the first right mold 6 has a small-diameter semi-hole 601 and a large-diameter semi-hole 602 from top to bottom. The lower end of the outer circumference of the first right mold 6 has a semi-circular frustum 603, and the upper end has a semi-conical surface 604. After the first left mold 5 and the first right mold 6 are combined into a whole rotating body, their lower surfaces abut against the plane 402 of the first anvil, and the semi-circular frustums 503 and 603 of the first left mold fit into the frustum hole 401 of the first anvil, forming a frictional self-locking relationship of the mold taper. The positioning relationship between the upper end of the first left mold 5 and the first right mold 6 and the first mold sleeve 7 is the same as that between the lower end, forming a frictional self-locking relationship through the conical surface fit. After the first left mold 5 and the first right mold 6 are combined into a single rotating body, the small-diameter semi-hole 501 of the first left mold and the small-diameter semi-hole 601 of the first right mold are adapted to the outer diameter of the initial ingot 9. The diameter of the large-diameter hole segment formed by the large-diameter semi-hole 502 of the first left mold and the large-diameter semi-hole 602 of the first right mold is larger than the diameter of the initial ingot 9. The height of the large-diameter semi-hole 502 of the first left mold and the large-diameter semi-hole 602 of the first right mold is less than 2.5 times the diameter of the initial ingot 9.

[0054] Before forging begins, the lower end of the initial ingot 9 contacts the highest point of the first anvil dome 403. The upper end of the initial ingot 9 contacts the lowest point of the first punch dome 801 of the first punch 8. The initial ingot 9 is cylindrical, with a height-to-diameter ratio exceeding 2.5 and a diameter less than 350 mm. The initial ingot 9 is preferably made of GH4065A alloy. After the first forging, the initial ingot 9 forms a stepped shaft-shaped forging 12 with concave upper and lower end faces.

[0055] See Figure 6 and Figure 7As shown in the embodiment of the present invention, the difference between the split forging die set used in the second forging and the split forging die set used in the first forging is that the second punch 11 used in the second forging is a flat-bottomed punch, and its flat end is used to contact the concave surface 1202 of the second forging of the corresponding first forging 12. The second anvil 10 used in the second forging is a flat anvil, and its flat end is used to contact the concave surface 1201 of the second forging of the first forging 12. The difference between the second left die 13 and the second right die 14 used in the second forging and the first left die 5 and the first right die 6 is that the height of the large-diameter half-hole is increased, that is, the large-diameter section of the first forging 12 contacts the large-diameter half-hole of the first left die 5 and the first right die 6, and the height of the large-diameter half-hole of the first left die 5 and the first right die 6 from the non-contact part of the first forging 12 is less than 2.5 times the diameter of the initial ingot 9. The first forging 12 is in a stepped shaft state, with the forging pressure creating a pattern of upper and lower constraint and middle deformation. After the second forging, a second forging is obtained, which is also a stepped shaft shape with flat upper and lower end faces. Compared to the first forging 12, the second forging has a longer height in the large diameter section. Similarly, subsequent forgings are performed sequentially.

[0056] See Figure 8 As shown in the embodiment of the present invention, the die set used for the Nth forging is a closed die structure, including the Nth anvil 15, the Nth left-side die 16, the Nth right-side die 17, the Nth die sleeve 20, and the Nth punch 19. After the Nth anvil 15, the Nth left-side die 16, the Nth right-side die 17, the Nth die sleeve 20, and the Nth punch 19 are engaged, they form a fully enclosed constraint on the Nth forging 18, achieving flash-free forging. The forging corresponding to the die set used for the Nth forging is a stepped forging disc shape, with three forging radii. Its microstructure is a uniform fine-grained microstructure, with an average grain size not lower than ASTM 8.0.

[0057] In adjacent forging cycles, the upper and lower ends of the forging and the die switch between concave and flat, and the diameter of the casting gradually increases. The dome shape of the punch and anvil is preferably obtained by simulating the upsetting process of the workpiece to be forged, obtaining the distribution of the deformation area during upsetting, and obtaining the special inner cavity shape and size based on the distribution of the free deformation area within the deformation area, with the aim of uniform and controllable grain size.

[0058] This invention provides a large turbine disk forging preparation device, employing a combination design of multiple sets of split mold groups and adaptable punches, suitable for difficult-to-deform high-temperature alloy ingots with a height-to-diameter ratio exceeding 2.5. By constraining the ingot's entire circumference through the mold cavity, combined with dimensional control ensuring the height of the large-diameter hole section is less than 2.5 times the ingot diameter, free deformation during the upsetting process is effectively limited. This completely eliminates the instability, bulging, and surface cracking phenomena caused by excessive height-to-diameter ratios in traditional forging, achieving stable forming of large height-to-diameter ratio ingots. The shape of the mold cavity is determined by simulating the deformation region distribution during the upsetting process of the forging workpiece, precisely matching the distribution law of the free deformation zone. This guides uniform metal flow within the ingot, fully breaking down the as-cast dendrite structure. Combined with the structural adaptability of multi-stage forging, it promotes sufficient dynamic recrystallization of the material, ultimately obtaining a uniform fine-grained structure with an average grain size not lower than ASTM 8.0, fully meeting the core requirements of large turbine disks for high-temperature strength, plasticity, and toughness, avoiding areas of insufficient crystal refinement present in traditional forging. This invention adopts a split mold structure to avoid the locking problem between the mold and the forging caused by thermodynamic and engineering mechanics factors in traditional tubular internal molds. It eliminates the need to design a draft angle and use glass lubricant powder or forging soft sleeve, completely preventing the scratching and damage of the crystal structure on the surface of the forging by lubricating materials or sleeves, and ensuring the surface smoothness and integrity of the forging.

[0059] Another embodiment of the present invention provides a method for preparing a large turbine disk forging, comprising the following steps:

[0060] Step S1: Prepare N sets of split forging die sets and N corresponding punches, where N is greater than or equal to 3;

[0061] Step S2: Heat N sets of split forging die sets and N corresponding punches to a predetermined temperature of 480°C to 490°C and hold at that temperature for 4 to 4.5 hours.

[0062] Step S3: Hold the initial ingot at 1000-1050℃ for 18-20 hours;

[0063] Step S4: Place the initial ingot after heat preservation into the first set of split forging molds, and use the corresponding punch to perform local upsetting and forging at a speed of 25mm / s~30mm / s until the outer circumference of the ingot matches the inner circumference of the mold to obtain a hot forging.

[0064] Step S5: Iteratively execute steps S3 and S4, replace the subsequent split forging die set for N-stage forging. In adjacent forging stages, the upper and lower ends of the forging and the die switch between concave and flat surfaces. The height of the large-diameter hole section of each die set satisfies the requirement that the height of the non-contact part of the corresponding forging is less than 2.5 times the initial ingot diameter, and finally obtains a stepped forging disc-shaped N-stage forging.

[0065] Another embodiment of this invention provides a method for preparing large turbine disk forgings. Addressing the problems of upsetting instability and insufficient crystal refinement in existing technologies caused by the height-to-diameter ratio limitation of difficult-to-deform high-temperature alloy ingots, this method employs an N-stage forging process, combined with a dedicated split-type mold assembly. By switching between concave and flat states at the upper and lower ends of adjacent forging stages and by precisely designing the mold cavity shape, stable upsetting of ingots with a height-to-diameter ratio exceeding 2.5 is achieved. This invention eliminates the need for a combined upsetting and drawing process, effectively breaks up the as-cast dendritic structure, obtains a uniform fine-grained structure with an average grain size reaching ASTM 8.0, eliminates upsetting instability and surface cracking, improves material utilization, and ensures consistent batch production quality. It is suitable for preparing large, difficult-to-deform high-temperature alloy turbine disk forgings.

[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A large turbine disk forging preparation apparatus, characterized in that, It includes N sets of split forging die sets and N corresponding punches, where N≥3. Each set of the split forging die sets includes an anvil, a left die, a right die, and a die sleeve. The left mold and the right mold are half of a rotating body with the same structure. The left mold and the right mold are combined to form a mold with a complete rotating body structure, and the combined mold forms an inner cavity that is adapted to the shape of the ingot or forging. The anvil is a rotating structure, and its upper end is provided with positioning holes that are adapted to the lower ends of the left and right molds; The mold sleeve is fitted around the outer periphery of the merged left and right molds, and the upper end of the mold sleeve is in a conical positioning fit with the left and right molds; The punch cooperates with the anvil to apply forging pressure to the ingot or forging in the mold, and the contact ends of the punch and the anvil used in adjacent forging operations are alternately arranged with concave and flat shapes.

2. The large turbine disk forging preparation apparatus according to claim 1, characterized in that, The inner cavity formed by the merging of the left mold and the right mold includes a small-diameter hole segment and a large-diameter hole segment. The diameter of the small-diameter hole segment is adapted to the outer diameter of the small-diameter segment of the corresponding fire-cast ingot or forging. The diameter of the large-diameter hole segment is larger than the outer diameter of the corresponding segment of the corresponding fire-cast ingot or forging.

3. The large turbine disk forging preparation apparatus according to claim 2, characterized in that, The height of the large-diameter hole section satisfies the following condition: the height of the non-contact portion with the corresponding ingot or forging is less than 2.5 times the initial ingot diameter.

4. The apparatus for preparing large turbine disk forgings according to claim 1, characterized in that, The punch used in the first forging is a dome punch, whose dome is used to contact the upper end face of the initial ingot; the punch used in the second forging is a flat-bottom punch, whose flat end is used to contact the upper recess of the corresponding forging. The anvil used in the first forging is a domed anvil, the domed end of which is used to contact the lower end face of the initial ingot; the anvil used in the second forging is a flat anvil, the flat end of which is used to contact the lower recess of the corresponding forging.

5. The apparatus for preparing large turbine disk forgings according to claim 1, characterized in that, The split forging die set used in the Nth forging is a closed die structure. After the left die, right die, anvil and punch are matched, they form a fully enclosed constraint on the Nth forging, realizing flash-free forging.

6. The apparatus for preparing large turbine disk forgings according to claim 1, characterized in that, The inner cavity shape of the mold is determined by simulating the deformation region distribution of the upsetting process of the forging workpiece to ensure that the grain size of the forging workpiece is uniform and controllable.

7. The apparatus for preparing large turbine disk forgings according to claim 1, characterized in that, The initial ingot is a cylindrical alloy ingot with a height-to-diameter ratio greater than 2.5 and a diameter less than 350 mm. The initial ingot is forged through N sets of split forging dies, and its diameter gradually increases.

8. The apparatus for preparing large turbine disk forgings according to claim 1, characterized in that, The forgings corresponding to the split forging die set used in the Nth forging are stepped forging discs. The forgings have three forging radii and their microstructure is a uniform fine-grained microstructure with an average grain size of not less than ASTM 8.

0.

9. The apparatus for preparing large turbine disk forgings according to claim 1, characterized in that, The positioning hole on the anvil is a frustum hole. The lower ends of the left mold and the right mold are provided with a semi-frustum. The semi-frustum fits into the frustum hole of the anvil to form a mold taper friction self-locking structure, which is used to ensure the stability of the mold after mold closing.

10. A method for preparing a large turbine disk forging using the device as described in any one of claims 1-9, characterized in that, Includes the following steps: Step S1: Prepare N sets of split forging die sets and N corresponding punches, where N is greater than or equal to 3; Step S2: Heat N sets of split forging die sets and N corresponding punches to a predetermined temperature of 480°C to 490°C and hold at that temperature for 4 to 4.5 hours. Step S3: Hold the initial ingot at 1000-1050℃ for 18-20 hours; Step S4: Place the initial ingot after heat preservation into the first set of split forging molds, and use the corresponding punch to perform local upsetting and forging at a speed of 25mm / s~30mm / s until the outer circumference of the ingot matches the inner circumference of the mold to obtain a hot forging. Step S5: Iteratively execute steps S3 and S4, replace the subsequent split forging die set for N-stage forging. In adjacent forging stages, the upper and lower ends of the forging and the die switch between concave and flat surfaces. The height of the large-diameter hole section of each die set satisfies the requirement that the height of the non-contact part of the corresponding forging is less than 2.5 times the initial ingot diameter, and finally obtains a stepped forging disc-shaped N-stage forging.

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