Forging method and die for journal alloy forge piece

Abstract

The invention relates to the technical field of alloy forge piece manufacturing, in particular to a forging method and die for a journal alloy forge piece. The method comprises the following steps: determining the size specification of a forging material; heating the forging material to a first forging temperature and preserving heat; performing one-heating blank making to obtain a prefabricated forging material with a positioning characteristic; the prefabricated forging material is wrapped with heat preservation cotton, returned to the furnace and heated to the second forging temperature, and heat preservation is conducted; the prefabricated forging material obtained after heat preservation is placed in a finish forging lower die, and positioning is conducted through the positioning characteristic of the prefabricated forging material and the finish forging lower die; a finish forging upper die is used for pressing the prefabricated forging material downwards, one-heating-number die forging is completed, and a die forging piece without a flash is obtained; by integrating the blank manufacturing procedure and the die forging procedure, only two heating times are needed, the special tool and die design is combined, the heating times are effectively reduced, flash is avoided, uniform deformation is ensured, and flash is avoided through the gap type die; and therefore, the metal flowing path is optimized, and material performance degradation in traditional multi-heating-number forging is prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy forging manufacturing, in particular to a forging method and die for journal alloy forgings. BACKGROUND

[0002] Large high-temperature alloy journal forgings are mostly used in some extreme environments in industrial production, and the materials are required to have excellent high-temperature resistance, corrosion resistance and mechanical strength, etc. The shape structure of such forgings is composed of a disc and a stepped shaft, which is similar to a mushroom-shaped body of revolution.

[0003] The structure of the above-mentioned journal forging is relatively special and the forming process also has certain difficulty. Not only is it required that the deformation of each part of the forging is relatively uniform during forming, but also the grain size grade of the forging body is improved, and the comprehensive mechanical performance indicators of the forging, such as high-temperature tensile, high-temperature endurance, high-temperature creep and high-cycle fatigue, are improved, so as to better serve in extreme harsh environments for a long time. Large journal forgings are mostly made of expensive high-temperature alloy, and due to the special nature of the material, the production and raw material cost are also relatively high. The traditional forging method usually deforms the forging stock by upsetting or elongating, and then performs multi-fire forging on a die forging press, but for large high-temperature alloy journal forgings, this method has the disadvantage that too many forging fires will cause the material to overheat, resulting in coarse grains or mixed crystal structure, which damages the performance of the material. SUMMARY

[0004] The main purpose of the present application is to provide a forging method for journal alloy forgings, which aims to solve the problem of coarse grains or mixed crystal structure in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides a forging method for journal alloy forgings, which is used for forging a forging stock into a flash-free journal alloy forging, and the method comprises the following steps: determining the size specification of the forging stock; heating the forging stock to a first forging temperature and keeping it warm; placing the kept-warm forging stock on a pre-fabricated lower tooling, using a pre-fabricated upper tooling to perform one-fire blanking to obtain a pre-fabricated forging stock with positioning features; wherein the pre-fabricated lower tooling has a stepped surface structure for constraining the radial freedom of the forging stock, and the pre-fabricated upper tooling has a sinusoidal curve cavity structure; wrapping the pre-fabricated forging stock with insulation cotton, and re-heating it to a second forging temperature and keeping it warm; placing the kept-warm pre-fabricated forging stock in a final forging lower die, and positioning it with the final forging lower die using the positioning features of the pre-fabricated forging stock; using a final forging upper die to press down the pre-fabricated forging stock to complete one-fire die forging, so as to obtain a flash-free die forging.

[0006] Optionally, determining the size specifications of the forging includes the following steps: The dimensions of the forging are determined based on the theoretical diameter of the journal alloy forging, and the following conditions must be met: The diameter of the forging is 0mm to 10mm smaller than the diameter of the plane of the platform at the journal of the journal alloy forging after it is moved down 50mm.

[0007] Optionally, in the process of heating the forging material to a first forging temperature and holding it at that temperature, the first forging temperature ranges from 960°C to 1000°C, and the holding time ranges from 240 min to 360 min.

[0008] Optionally, the heating temperature for the single-pass blanking is 980℃, the deformation rate is 8mm / s, and the deformation range is 0~70%.

[0009] Optionally, the deformation rate of the single-pass forging is 5 mm / s.

[0010] Optionally, during the reheating to a second forging temperature and holding, the second forging temperature ranges from 980°C to 1040°C, and the holding time ranges from 60 min to 120 min.

[0011] Optionally, wrapping the precast forged material with insulation cotton includes the following steps: Insulating cotton is wrapped around the upper end of the preformed forging to increase the dynamic recrystallization driving force of the forging during the die forging process.

[0012] To achieve the above objectives, the present invention also provides a forging die, the forging die comprising: Forging fixture, the forging fixture includes a pre-made upper fixture and a pre-made lower fixture, the pre-made upper fixture is provided with a sinusoidal curve cavity structure, the pre-made lower fixture is provided with positioning features, and the pre-made upper fixture and the pre-made lower fixture are used to cooperate to perform one-time billet production. The final forging die includes an upper final forging die, a lower final forging die, and a lower ejector rod. The upper final forging die has a protruding structure at the center of its cavity, and the outer diameter of the protruding structure decreases from top to bottom. The lower final forging die also has a sinusoidal curve cavity structure at the center of its cavity, and the lower ejector rod moves through the lower final forging die.

[0013] Optionally, after the upper and lower molds of the final forging die are fitted together, the gap between the mating surfaces ranges from 2 mm to 2.3 mm.

[0014] Optionally, the slope of the protruding structure ranges from 3.5° to 4.5°, and the rounded corners are designed to be R15mm.

[0015] Optionally, the positioning feature is a stepped surface, the step surface has a drop of 50mm, and the outer diameter of the step surface is the diameter at which the plane of the platform at the journal of the journal alloy forging intersects with the curvature of revolution of the journal alloy forging after the plane is moved down parallel to the journal by 50mm.

[0016] Optionally, the difference between the outer diameter and the inner diameter of the positioning feature is in the range of 30 mm to 50 mm.

[0017] Optionally, the slope of the mating surface between the upper and lower final forging dies is 2°.

[0018] This invention integrates the billet preparation and die forging processes, requiring only two heating cycles. Combined with specialized tooling and die design, it effectively reduces the number of heating cycles, avoids flash, and ensures uniform deformation. The dimensions of the forging material are determined based on the geometric characteristics of the journal alloy forging to ensure it fits the die cavity in subsequent forging, avoiding incomplete filling or material waste due to dimensional deviations. Furthermore, the forging material is heated to a first forging temperature and held to achieve a uniform plastic state, providing suitable deformation conditions for billet preparation and reducing deformation resistance. Subsequently, the held-temperature forging material is placed on a pre-fabricated lower tooling and subjected to a single heating cycle using a pre-fabricated upper tooling. The stepped surface structure of the pre-fabricated lower tooling constrains the radial degree of freedom of the forging material, preventing lateral flow, while the pre-fabricated upper tooling... The sinusoidal cavity structure is specially designed to guide the metal flow along the curved path, promoting uniform deformation during the billet preparation stage and forming positioning features. After the pre-forged material is wrapped with insulating cotton, it is reheated in the furnace to the second forging temperature. The insulation cotton maintains the temperature uniformity of the forging material, reduces heat loss, provides a stable thermal environment for die forging, and prevents local overheating or incomplete filling caused by uneven temperature. Then, the pre-forged material after insulation is placed in the lower die of the final forging process. The positioning features of the pre-forged material are used to position it with the lower die of the final forging process, achieving rapid and accurate alignment, ensuring stable position during die forging, and avoiding geometric deviations caused by offset. Finally, the upper die of the final forging process presses down on the pre-forged material to complete the single-fire die forging, and the gap die design avoids the generation of flash. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the method in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the forging fixture in Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the prefabricated upper tooling structure in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the prefabricated lower tooling in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of the final forging die in Embodiment 2 of the present invention; Figure 6This is a schematic diagram of the final forging die in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram of the final forging die in Embodiment 2 of the present invention.

[0020] Figure label: 1-Forging fixture, 11-Prefabricated upper fixture, 12-Prefabricated lower fixture; 2-Final forging die, 21-Upper final forging die, 22-Lower final forging die, 23-Lower ejector pin.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0026] Example 1: As attached Figure 1 As shown, this embodiment provides a forging method for journal alloy forgings. The method is used to forge a forging material into a journal alloy forging without flash. The method includes the following steps: Determine the dimensions and specifications of the forging; The forging material is heated to the first forging temperature and held at that temperature; The heat-insulated forging is placed on the prefabricated lower tooling 12, and the prefabricated upper tooling 11 is used to perform one-time blanking to obtain a prefabricated forging with positioning characteristics; wherein, the prefabricated lower tooling 12 has a stepped surface structure for constraining the radial degree of freedom of the forging, and the prefabricated upper tooling 11 has a sinusoidal curve cavity structure. The precast forging is wrapped with insulating cotton, then reheated in the furnace to the second forging temperature and kept warm. The heat-insulated pre-forged material is placed in the final forging lower die 22, and the positioning characteristics of the pre-forged material are used to position it with the final forging lower die 22. The pre-formed forging material is pressed downward using the final forging die 21 to complete a single-pass forging process, thereby obtaining a forging without flash.

[0027] It should be noted that several key technical problems remain to be solved in the forging process of traditional large high-temperature alloy journal forgings. Specifically, excessive forging passes can easily lead to material overheating, resulting in coarse grains or mixed grain structures, which adversely affects the high-temperature tensile properties, high-temperature creep properties, high-temperature creep properties, and high-cycle fatigue properties of the forgings. At the same time, the multi-pass forging process requires the switching of multiple sets of tooling / dies, which not only prolongs equipment occupancy time and increases energy consumption, but also significantly increases manufacturing costs. In addition, the metal flow path is difficult to control effectively under the traditional open die forging method, resulting in uneven deformation distribution and defects such as incomplete filling of deep cavity areas in the forgings. Furthermore, the flash generated during the die forging process further reduces the utilization rate of raw materials, affecting the overall process economy.

[0028] Based on the above problems, this embodiment proposes a forging method for journal alloy forgings, used to forge forgings into journal alloy forgings without flash. The stepped surface structure of the prefabricated lower tooling 12 refers to a stepped surface on the lower tooling used to constrain the radial degree of freedom of the forging. This can be achieved using step designs with different geometric profiles, preferably inclined transition steps, primarily to limit the radial displacement of the forging during the forging process. Furthermore, the sinusoidal cavity structure of the prefabricated upper tooling 11 can also be achieved using other periodic curved cavity structures, such as cosine curves or parabolic cavity structures, primarily to regulate the metal flow path to promote uniform deformation distribution.

[0029] It should also be noted that in practical applications, wrapping the precast forging with insulation cotton can be done by covering specific areas of the forging with the insulation material, such as using aluminum silicate fiber felt to wrap the central area of ​​the forging. This is mainly to reduce heat loss and maintain temperature field stability. The positioning features of the precast forging can be achieved using boss or groove structures, such as forming an annular groove on the surface of the precast forging. This is mainly to cooperate with the corresponding structure of the final forging die 22 to achieve positional calibration. Specifically, completing a single-pass forging is mainly to prevent metal overflow and flash formation and to improve material utilization efficiency.

[0030] In summary, this embodiment integrates the billet preparation and die forging processes and optimizes the tooling structure design, requiring only two heating cycles to complete the forging process. This effectively avoids the problems of material overheating and coarse grains caused by multiple heating cycles, while eliminating flash and ensuring uniform metal deformation. Thus, it solves the technical problems of excessive heating cycles, high mold costs, uneven metal flow, and material waste in traditional methods.

[0031] Understandably, the above methods significantly reduce the number of forging passes, preventing material overheating and coarse grains; closed-die forging eliminates flash and improves raw material utilization; the stepped surface structure and sinusoidal cavity ensure uniform metal flow, avoiding incomplete filling. Specifically, by precisely controlling the forging size and temperature parameters, the metal flow path is optimized, preventing material performance degradation in traditional multi-pass forging; special tooling design enables efficient connection between billet preparation and die forging processes, reducing equipment occupancy and energy consumption; the introduction of positioning features ensures the geometric accuracy of the die forging process, thus comprehensively solving the technical problems of excessive forging passes leading to material overheating and coarse grains, increased costs and energy consumption caused by multiple dies, incomplete filling due to uneven metal flow, and low raw material utilization due to flash in large high-temperature alloy journal forgings.

[0032] In this embodiment, determining the size specifications of the forging includes the following steps: The dimensions of the forging are determined based on the theoretical diameter of the journal alloy forging, and the following conditions must be met: The diameter of the forging is 0mm to 10mm smaller than the diameter of the plane of the platform at the journal of the journal alloy forging after it is moved down 50mm.

[0033] By dynamically linking the forging dimensions with the geometric characteristics of the stress concentration region in the journal forging, the basic dimensional parameters are first determined based on the theoretical diameter. Then, a reference plane is positioned 50mm lower to obtain the intersection diameter with the surface of revolution. Subsequently, the forging diameter is set to be slightly smaller than this intersection diameter. During the die forging stage, this interference range promotes the uniform extension of the metal material along the deep cavity contour under dynamic recrystallization conditions. This ensures sufficient filling of the metal to the bottom of the cavity to eliminate incomplete filling defects, while strictly constraining the radial flow of metal volume to suppress flash formation. This achieves synergistic optimization of metal flow behavior and cavity geometry. Consequently, it effectively solves the problem of imbalance between metal flow and cavity matching during die forging, reduces flash generation and incomplete filling defects, and improves material utilization and forging quality.

[0034] In this embodiment, during the heating and holding of the forging material to a first forging temperature, the first forging temperature ranges from 960°C to 1000°C, and the holding time ranges from 240 min to 360 min.

[0035] Understandably, the first forging temperature range refers to the temperature range for heating the forging material, which can be set to specific values ​​such as 960℃, 970℃, 990℃, or 1000℃. Its purpose is to ensure that the material is in a suitable single-phase temperature range, which can provide sufficient plasticity to adapt to subsequent billet deformation, while avoiding abnormal grain growth caused by excessive temperature. The holding time range refers to the duration of holding, which can be specific durations such as 240min, 270min, 330min, or 360min. Its purpose is to ensure that the internal temperature of the material is fully and uniformly distributed, providing stable thermodynamic conditions for single-pass billet forming, while preventing uneven deformation caused by insufficient holding time or grain coarsening caused by excessive holding time.

[0036] It is also understandable that the above steps, by heating the forging to the first forging temperature range and holding it at that temperature within the holding time range, enable the material to reach a uniform thermodynamic state before billet formation. The selection of the temperature range is based on the phase transformation characteristics of high-temperature alloys, which avoids abnormal grain growth. At the same time, the control of the holding time is based on the size characteristics and heat conduction law of large forgings, which ensures uniform temperature distribution, thereby providing stable conditions for subsequent single-pass billet formation and effectively preventing structural defects caused by overheating of the material.

[0037] In this embodiment, the heating temperature of the first-pass blanking is 980℃, the deformation rate is 8mm / s, and the deformation range is 0~70%.

[0038] It should be noted that a complete technical system is formed through the coordinated control of heating temperature, deformation rate, and deformation amount: the heating temperature of 980℃ is set to maintain the high-temperature alloy in its optimal state within the plastic deformation window, ensuring that the material flow stress is within a suitable range; the deformation rate of 8mm / s is configured to match the metal's hot deformation dynamics, ensuring that the metal flows stably and continuously along the sinusoidal cavity structure during the pressing process; the deformation amount range of 0~70% is adjusted to balance recrystallization requirements and geometric forming accuracy, enabling the forging to achieve radially uniform deformation under the constraint of the stepped surface structure. The precise combination of the above parameters effectively suppresses the non-uniformity of metal flow, avoids the problem of insufficient filling of deep cavities, and provides process assurance for the formation of precise positioning features in the pre-formed forging.

[0039] In this embodiment, the deformation rate of the single-fusing die is 5 mm / s. By setting the deformation rate of the single-fusing die to 5 mm / s, in coordination with the second forging temperature range and holding time, the metal flows along the cavity surface at a stable speed during the final forging pressing stage. This rate, based on the plastic deformation characteristics and thermal conductivity of high-temperature alloys at high temperatures, effectively controls the thermodynamic behavior during the pressing process, preventing local overheating or sudden temperature drops due to improper rates. This promotes uniform filling of the metal within the sinusoidal cavity structure and drives the orderly progress of the dynamic recrystallization process, ultimately achieving grain refinement and uniform distribution.

[0040] In this embodiment, during the reheating to the second forging temperature and holding, the second forging temperature ranges from 980°C to 1040°C, and the holding time ranges from 60 min to 120 min.

[0041] It should be noted that the second forging temperature range refers to the precise control range of the material heating temperature before die forging. It can be achieved by using a resistance furnace or a gas furnace in conjunction with a high-precision thermocouple and a closed-loop temperature control system. The purpose is to avoid grain boundary weakening and abnormal grain growth caused by excessively high temperatures, while preventing a surge in deformation resistance and cavity filling defects caused by excessively low temperatures. The holding time range refers to the constant temperature period maintained at the second forging temperature. It can be achieved by using a programmable timer combined with the material's thermal conductivity characteristics for dynamic adjustment. The purpose is to ensure a uniform temperature field distribution inside the forging material, promote sufficient dynamic recrystallization, and thus balance the risks of thermal stress concentration and grain coarsening.

[0042] It should also be noted that the above method, by strictly limiting the second forging temperature to the range of 980℃ to 1040℃, enables the high-temperature alloy to obtain suitable plastic flow capacity during the die forging stage, which not only suppresses the microstructure deterioration caused by overheating, but also ensures the uniform filling of the metal into the deep cavity. At the same time, by controlling the holding time to the range of 60min to 120min, the temperature homogenization and recrystallization kinetics process are effectively coordinated, allowing the internal thermal stress of the material to be fully released and the grain structure to be refined. The synergistic effect of the two ensures the controllability of deformation behavior and the stability of microstructure evolution during the die forging process.

[0043] In this embodiment, wrapping the precast forged material with insulation cotton includes the following steps: Insulating cotton is wrapped around the upper part of the pre-forged material to increase the dynamic recrystallization driving force during the die forging process. By precisely positioning the insulating cotton around the upper part of the pre-forged material, the characteristic that this area preferentially contacts the final forging die 21 during final forging effectively suppresses rapid heat loss. Since the upper part is prone to a sudden temperature drop due to the initial impact force, maintaining a local high-temperature environment here significantly enhances the dynamic recrystallization driving force. The optimized temperature gradient makes it easier for the metal to recrystallize fully during deformation, avoiding the temperature distribution imbalance caused by traditional uniform wrapping, thereby ensuring grain refinement and microstructure uniformity.

[0044] Example 2: Please refer to the attached document as well. Figures 2 to 7 This embodiment provides a forging die, the forging die comprising: Forging fixture 1, the forging fixture 1 includes a pre-made upper fixture 11 and a pre-made lower fixture 12, the pre-made upper fixture 11 is provided with a sinusoidal curve cavity structure, the pre-made lower fixture 12 is provided with positioning features, and the pre-made upper fixture 11 and the pre-made lower fixture 12 are used to cooperate to perform one-time billet forming. The final forging die 2 includes an upper final forging die 21, a lower final forging die 22, and a lower ejector rod 23. The upper final forging die 21 has a protruding structure at the center of its cavity, and the outer diameter of the protruding structure decreases from top to bottom. The lower final forging die 22 also has a sinusoidal curve cavity structure at the center of its cavity, and the lower ejector rod 23 moves through the lower final forging die 22.

[0045] Based on the above structure, this embodiment combines the sinusoidal cavity structure with the positioning features in a single-fire forging method, thereby significantly reducing the number of heating fires to avoid material overheating and coarse grains; at the same time, the convex structure of the upper forging die 21 and the sinusoidal cavity structure of the lower forging die 22 work together in a closed-die forging method to guide the metal to flow uniformly along the curved path and suppress flash formation, thereby improving the utilization rate of raw materials and the uniformity of the internal structure of the forging.

[0046] Specifically, the sinusoidal cavity structure of the prefabricated upper tooling 11, in conjunction with the positioning features of the prefabricated lower tooling 12, generates a prefabricated forging with a precise geometric profile during the billet preparation stage. This ensures stable positioning within the final forging die 22, preventing incomplete filling defects caused by uneven metal flow. The design of the outer diameter of the protruding structure of the final forging upper die 21, decreasing from top to bottom, effectively guides the metal to flow directionally towards the cavity sidewall through slope control, preventing overflow into the flash area. Combined with the sinusoidal cavity structure of the final forging lower die 22, it maintains surface continuity, further optimizing the deformation path and reducing the risk of local overheating. The lower ejector rod 23 moves through the final forging lower die 22, assisting in ejecting the forging by dynamically adjusting the metal flow resistance, ensuring the complete forming of the flash-free die forging. Thus, this embodiment integrates the billet preparation and final forging functions, requiring only two heating cycles to complete the forging process. This effectively solves the material performance degradation problem caused by traditional multi-heating processes and significantly improves raw material utilization efficiency by eliminating flash through the closed die structure.

[0047] In this embodiment, after the upper forging die 21 and the lower die are fitted together, the gap between their mating surfaces ranges from 2mm to 2.3mm. By limiting the gap between the mating surfaces to a specific range of 2mm to 2.3mm, based on the dynamic balance between the rheological properties of the high-temperature alloy at the forging temperature and the thermal expansion behavior of the die, it is ensured that the metal obtains a suitable flow driving force during the final forging pressing process. When the gap is within this range, sufficient cavity constraint force is maintained to prevent metal loss along the mating surface, while avoiding excessive closing resistance that could lead to uneven local deformation. This gap design effectively matches the sinusoidal cavity structure of the final forging die 2, optimizing the filling path of the metal into the deep cavity region, thereby achieving precise control of metal flow behavior under the goal of flash-free forging.

[0048] In this embodiment, the slope of the protruding structure ranges from 3.5° to 4.5°, and the fillet is designed to be R15mm. It is understood that the slope of the protruding structure refers to the angle between the outer surface of the protruding structure and the vertical direction, which can be any continuous value within the range of 3.5° to 4.5°, such as 3.8°, 4.0°, or 4.2°. Its purpose is to ensure that the metal transitions smoothly into the depth of the cavity at an appropriate rate during final forging, avoiding insufficient filling due to excessive flow resistance caused by an insufficient slope, or uneven deformation due to excessive flow caused by an excessively large slope. The fillet design refers to the transition radius of the protruding structure's edge, which can be a standard fillet of R15mm. Its purpose is to buffer the stress concentration effect during the pressing process, prevent crack defects at the corners of the cavity due to excessive stress, and maintain the continuity of metal flow.

[0049] In this embodiment, the positioning feature is a stepped surface with a drop of 50mm, and the outer diameter of the stepped surface is the diameter at which the plane of the platform at the journal of the journal alloy forging intersects with the curvature of the journal alloy forging after the plane is moved down 50mm parallel to the plane.

[0050] By using the stepped surface as a positioning reference surface, combined with the precise setting of the drop and outer diameter, the pre-forged material can be quickly centered and stably fixed in the final forging die 22. The stepped surface provides clear axial and radial positioning references, ensuring that the forging material is in the correct position at the beginning of the pressing stage; the drop is set to 50mm, based on the structural characteristics of the journal forging, ensuring sufficient positioning depth to prevent forging material deviation, while avoiding excessive height that would hinder the flow of metal into the depth of the cavity; the outer diameter is determined according to the geometric relationship of the revolution surface of the journal alloy forging, so that the upper end of the pre-forging material fits tightly with the die cavity, guiding the metal to be evenly distributed along a predetermined path during the pressing process, thereby reducing local stress concentration and suppressing flash formation.

[0051] In this embodiment, the difference between the outer diameter and the inner diameter of the positioning feature ranges from 30mm to 50mm. By limiting the difference between the outer and inner diameters of the positioning feature to within the range of 30mm to 50mm, the width of the step surface is kept moderate. When the difference is within this range, the step surface can provide sufficient support area, effectively preventing the preformed forging from shifting during the pressing process, while not excessively hindering the flow of metal into the depth of the cavity. This promotes uniform metal distribution and complete filling of the cavity, avoiding the generation of flash.

[0052] In this embodiment, the slope of the mating surfaces of the upper forging die 21 and the lower forging die 22 is 2°. By setting the slope of the mating surfaces to 2 degrees, the metal is guided by the slope during high-pressure deformation, preferentially filling into the cavity rather than overflowing laterally along the gap. This specific angle provides appropriate flow control while ensuring the structural strength of the die. It prevents disordered metal overflow caused by perpendicular mating surfaces and avoids flow turbulence or uneven filling caused by excessive slope, thereby ensuring complete filling of the deep cavity area of ​​the forging and uniform overall deformation.

[0053] Example 3: To make the technical solution of the present invention clearer, in this embodiment, a heavy-duty gas turbine journal forging is used as an example to describe the manufacturing method of the present invention in detail. Specifically, the outer contour dimensions of the forging are φ890 (outer contour) × 690 (height) mm, the plane of the platform at the neck (journal) of the forging is translated downward by 50 mm, and the diameter where it intersects with the curved surface of the neck of the forging is 418 mm. The weight of the forging is 1155 kg. The specific manufacturing steps include: Step 1: Design the cylindrical forging material, forging fixture 1, final forging die 2, and lower ejector pin 23 according to the external dimensions of the forging. Among them, the cavity of the prefabricated upper fixture 11 adopts a sinusoidal curve structure; the cavity of the prefabricated lower fixture 12 and the contact end with the forging material adopt a "stepped surface" structure design with a step drop of 50mm. The outer diameter of the annular plane for placing the round bar in the cavity of the prefabricated lower fixture 12 is 418mm, and the inner diameter is 380mm; the final forging upper die 21 has a protruding plane feature that extends into the cavity of the final forging lower die 22. The slope of this part is designed to be 4°, and the fillet is designed to be R15mm; the bottom cavity of the final forging lower die 22 is designed with a sinusoidal curve; the top structural features of the lower ejector pin 23 are consistent with the sinusoidal curve design of the bottom cavity of the final forging lower die 22. The slope of the mating position of the upper forging die 21 and the lower forging die 22 is designed to be 2°; after the forging die 2 is closed, the gap between the upper and lower dies is 2.2mm, and the outer dimensions of the billet are 410mm in diameter and 1090mm in length. Step 2: Heat the forging material to the forging temperature of 980℃ and hold for 300 minutes; Step 3: After the forging is heated, it is placed on the "stepped surface" structure of the cavity of the prefabricated lower tooling 12. The prefabricated upper tooling 11 moves downward at a speed of 8 mm / s to press the forging, completing the single-fire billet forming operation. The cavity of the prefabricated upper tooling 11 has a sinusoidal curve structure, and the cavity of the prefabricated lower tooling 12 has a "stepped surface" structure, which reduces the contact area between the billet and the tooling during the deformation process, thus resulting in a lower forming load. In addition, the cavity feature of the prefabricated lower tooling 12 has an adaptive positioning feature for round bars, which can directly place the round bars on the annular plane and constrain their radial degrees of freedom, enabling rapid and accurate positioning. This prevents the cylindrical forging from deviating from the center position of the lower die of the prefabricated lower tooling 12, causing the billet to bend.

[0054] Step 4: After the first-pass billet preparation is completed, wrap the upper end of the pre-forged material with insulating cotton containing high-temperature binder, and reheat it in the furnace to the forging temperature; forging temperature 1010℃, hold for 90 minutes; Step 5: Place the heated pre-forged material into the cavity of the lower final forging die 22. The pre-forged material obtained by the first forging process has self-adaptive positioning characteristics, which can quickly complete the positioning with the cavity of the lower final forging die 22. The upper final forging die 21 presses the pre-forged material downward to the predetermined position, and finally completes the filling to obtain a die forging without flash.

[0055] It is understandable that if the forgings in the above embodiments are forged using traditional die forging methods, the required material weight is 1360 kg, requiring two forging passes, one pre-forging pass, and one final forging pass. After die forging, the flash also needs to be removed. However, using the technology of this invention, the material weight of the forging is reduced from 1360 kg to 1180 kg, a reduction of 13.2%; the number of forging passes is reduced from 4 to 2, a reduction of 50%; and only burrs need to be ground after die forging, without the need to remove the flash. This has significant economic benefits. As can be seen from the above data, the technology of this invention has significant beneficial results.

[0056] It is also understandable that in the above process, by designing adaptive positioning features for the forging fixture 1, the round bar and billet are automatically and quickly positioned during the billet preparation and die forging processes, respectively, and the placement position is accurate, while reducing the difficulty of on-site operation. It effectively reduces the die forging forming load and raw material cost. The traditional process has a large final forging forming load of about 80,000 tons, which causes wear and tear on the equipment and is not conducive to the complete filling of the forging metal material. The die forging forming load of this invention is only 53,000 tons, which is reduced by 33%, while the raw material consumption is reduced by 10%, and flash-free forging is achieved. Compared with the traditional manufacturing method, this invention reduces the number of forging fires. The traditional method requires 2 fires for billet preparation, 1 fire for pre-forging, and 1 fire for final forging, which increases the investment in manufacturing process and mold tooling, and increases manufacturing cost. The solution of this invention only requires 1 fire for billet preparation and 1 fire for die forging, which greatly shortens the manufacturing cycle and has significant economic benefits.

[0057] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A forging method for a journal alloy forging, characterized in that, Includes the following steps: Determine the dimensions and specifications of the forging; The forging material is heated to the first forging temperature and held at that temperature; The heat-insulated forging is placed on the prefabricated lower tooling, and the prefabricated upper tooling is used to perform one-time billet forming to obtain a prefabricated forging with positioning characteristics; wherein, the prefabricated lower tooling has a stepped surface structure for constraining the radial degree of freedom of the forging, and the prefabricated upper tooling has a sinusoidal curve cavity structure. The precast forging is wrapped with insulating cotton, then reheated in the furnace to the second forging temperature and kept warm. The heat-insulated pre-forged material is placed in the final forging lower die, and the positioning characteristics of the pre-forged material are used to position it with the final forging lower die. The pre-formed forging material is pressed downwards using the final forging die to complete a single-pass forging process, thereby obtaining a forging without flash.

2. The forging method for a journal alloy forging as described in claim 1, characterized in that, Determining the size specifications of the forging includes the following steps: The dimensions of the forging are determined based on the theoretical diameter of the journal alloy forging, and the following conditions must be met: The diameter of the forging is 0mm to 10mm smaller than the diameter of the plane of the platform at the journal of the journal alloy forging after it is moved down 50mm.

3. The forging method for a journal alloy forging as described in claim 1, characterized in that, The process of heating the forging material to a first forging temperature and holding it at that temperature, wherein the first forging temperature ranges from 960°C to 1000°C and the holding time ranges from 240 min to 360 min.

4. The forging method for a journal alloy forging as described in claim 1, characterized in that, The heating temperature for the single-pass blanking process is 980℃, the deformation rate is 8mm / s, and the deformation range is 0~70%.

5. The forging method for a journal alloy forging as described in claim 1, characterized in that, The deformation rate of the single-pass forging is 5 mm / s.

6. The forging method for a journal alloy forging as described in claim 1, characterized in that, The furnace is being reheated to a second forging temperature and held at that temperature. The second forging temperature ranges from 980°C to 1040°C, and the holding time ranges from 60 min to 120 min.

7. The forging method for a journal alloy forging as described in claim 1, characterized in that, The step of wrapping the precast forging material with insulation cotton includes the following steps: Insulating cotton is wrapped around the upper end of the preformed forging to increase the dynamic recrystallization driving force of the forging during the die forging process.

8. A forging die, characterized in that, The forging die is used to complete the forging method of a journal alloy forging according to any one of claims 1 to 7, and the forging die includes: Forging fixture, the forging fixture includes a pre-made upper fixture and a pre-made lower fixture, the pre-made upper fixture is provided with a sinusoidal curve cavity structure, the pre-made lower fixture is provided with positioning features, and the pre-made upper fixture and the pre-made lower fixture are used to cooperate to perform one-time billet production. The final forging die includes an upper final forging die, a lower final forging die, and a lower ejector rod. The upper final forging die has a protruding structure at the center of its cavity, and the outer diameter of the protruding structure decreases from top to bottom. The lower final forging die also has a sinusoidal curve cavity structure at the center of its cavity, and the lower ejector rod moves through the lower final forging die.

9. A forging die as described in claim 8, characterized in that, After the upper and lower molds of the final forging die are fitted together, the gap between the mating surfaces ranges from 2mm to 2.3mm.

10. A forging die as described in claim 8, characterized in that, The slope of the protruding structure ranges from 3.5° to 4.5°, and the rounded corners are designed to be R15mm.

11. A forging die as described in claim 8, characterized in that, The positioning feature is a stepped surface with a drop of 50mm, and the outer diameter of the stepped surface is the diameter at which the plane of the platform at the journal of the journal alloy forging intersects with the curvature of the journal alloy forging after the plane is moved down 50mm parallel to the plane.

12. A forging die as described in claim 8, characterized in that, The difference between the outer diameter and the inner diameter of the positioning feature is in the range of 30mm to 50mm.

13. A forging die as described in claim 8, characterized in that, The slope of the mating surface between the upper and lower forging dies is 2°.

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