A process for preforming a large superalloy cone disc green tire mold blank

Abstract

The present application belongs to the technical field of forging of high-temperature alloy conical disc forgings, and particularly relates to a process method for preforming of a large high-temperature alloy conical disc die blank. The present application realizes uniform deformation by means of the "die blank", distributes deformation of each part by means of "die preforming", removes the deformation dead zone through local cold die layer processing in the subsequent process, realizes die forging deformation distribution, realizes uniformity of the structure by means of "die forging", and uses small equipment to do big things, and completes the hot working process of the structure and the performance under the controllable deformation condition.

Description

Technical Field

[0001] This invention belongs to the field of forging technology for high-temperature alloy cone-shaped forgings, specifically relating to a process method for preforming large high-temperature alloy cone-shaped forging blanks using a mold. Background Technology

[0002] With the development of domestically produced aerospace engines, the working environment of engine components is becoming increasingly harsh. GH4169 is widely used in conditions ≤650℃, and it has been reported that GH4169 material accounts for more than 34% of the total weight of aero-engines. As a key component of the engine, this conical disc forging requires that all performance aspects meet the requirements and be free of defects. Its structure requires deformation in both the radial and axial directions, and the deformation must be uniform to prevent inconsistent microstructure caused by uneven deformation in different parts of the forging process. Therefore, the consistency of deformation during its forming process is particularly important. Current production processes use upsetting to form a billet and die forging, which requires large equipment tonnage and has a large deformation dead zone, making it impossible to effectively guarantee microstructure uniformity and resulting in localized uneven deformation in the forging. Summary of the Invention

[0003] Purpose of the invention: To provide a process method for preforming a large high-temperature alloy conical disc blank using a mold, establishing a process of "mold blank making" to achieve uniform deformation, "mold preforming" to distribute the deformation of each part, and subsequent processing of local cold mold layers to remove deformation dead zones, thereby achieving the distribution of deformation in die forging, and "die forging" to achieve uniform microstructure. Moreover, it uses small equipment to do a lot of work, and completes the heat treatment process of microstructure and properties under controllable deformation conditions.

[0004] Technical solution:

[0005] A process for preforming a large high-temperature alloy conical disc mold blank includes:

[0006] The first step is upsetting the mold: The mold has a vertically oriented, rotationally symmetrical cavity running along its axis. Along its longitudinal direction, it includes a first through hole, a second through hole, a third through hole, and an ejector through hole located below the third through hole. The inner diameter of the first through hole is larger than the outer diameter of the large end of the forging; the inner diameter of the second through hole is smaller than the outer diameter of the small end of the forging; the sum of the heights of the first and second through holes is less than the axial height of the forging; the lower section of the upsetting ejector plate has the same shape as the third through hole, and the middle section has the same shape as the lower part of the second through hole, with a first positioning platform on its upper surface; the height of the first positioning platform is greater than the height of the second through hole; the lower section of the pre-forming ejector plate has the same shape as the third through hole, with a second positioning platform on its upper surface.

[0007] First, the bar stock with a height of h and a φ250mm-φ300mm and pre-machined positioning holes is heated to the deformation temperature by upsetting with a mold. After heat preservation, it is placed on the mold with the upsetting ejector plate installed. The upper mold is a flat mold. The initial mold parting distance H1 is equal to the bar stock height h minus the height of the first through hole of the mold. The bar stock is pressed down to the reserved height A with a gradually decreasing pressing speed. After air cooling for 10 minutes, it is returned to the furnace for reheating.

[0008] The second step is preforming the mold: after the forging is heated by replacing the preforming ejector plate, place the forging on the preforming mold. The initial parting surface distance is H2. Press the bar down to the parting surface distance of 2mm with a gradually decreasing pressing speed.

[0009] Step 3: Die forging: Heat the processed rough die to the deformation temperature. After heat preservation, place the rough die on the final forging die and press it down at a gradually decreasing speed until the parting surface is 6mm away. Then, use air cooling.

[0010] Furthermore, the sides of the first through hole, the second through hole, and the third through hole have draft angles.

[0011] Furthermore, the height of the first through hole is one-third to one-quarter of the height of the forging.

[0012] Furthermore, the minimum distance between the second positioning platform and the upper surface of the mold is 35-45mm.

[0013] Furthermore, during the upsetting process of the die, the bar stock is pressed down to the reserved height A at a gradually decreasing pressing speed. Specifically, this includes: first pressing it down to one-half to two-thirds of the difference between the initial parting distance H1 and the reserved height A at an initial speed of 7 mm / s to 8 mm / s; then pressing it down to the reserved height A at 4 mm / s, air-cooling it for 10 minutes, and then reheating it in the furnace.

[0014] Furthermore, during the pre-forming process of the mold, the bar stock is pressed down to a distance of 2mm from the parting surface at a gradually decreasing pressing speed. Specifically, this includes pressing down to one-third of the initial parting surface distance H2 at an initial speed of 5mm / s, and then pressing down to a distance of 2mm from the parting surface at 3mm / s.

[0015] Furthermore, the third step, prior to die forging, includes: machining to remove the cold die layer and core skin of the rough mold.

[0016] Furthermore, in the third step, the pressure is gradually reduced until the parting surface is 6mm away, and air cooling is provided. Specifically, this includes: first pressing at an initial speed of 7mm / s to three-quarters of the forging pressure, then pressing at 3mm / s to the parting surface distance of 6mm, and air cooling is provided.

[0017] Beneficial effects:

[0018] This forming method uses a set of molds and two ejector plates for upsetting and preforming, which effectively distributes the deformation amount. The subsequent die forging process can obtain forgings with qualified dimensions and performance with a smaller tonnage, thereby improving the unevenness of forging deformation while saving economic costs. Attached Figure Description

[0019] Figure 1 Drawing of GH4169 cone-shaped die forging;

[0020] Figure 2 A schematic diagram of the mold and upsetting ejector plate during the upsetting process;

[0021] Figure 3 This is a schematic diagram of the mold and preforming ejector platen during the preforming process;

[0022] Figure 4 Diagram showing the removal of the cold mold layer by machining;

[0023] Figure 5 This is a drawing of a forging die. Detailed Implementation

[0024] This invention focuses on forgings of this shape (e.g.) Figure 1 This method, designed to address the issue of inconsistent microstructure, overturns the traditional "free blanking + die forging" method. Instead, it establishes a new method based on "mold blanking" to achieve uniform deformation, "mold pre-forming" to distribute deformation across different parts, and subsequent processing of local cold mold layers to remove deformation dead zones, thus achieving uniform microstructure through "die forging." Furthermore, it utilizes small equipment to perform large-scale tasks, completing the thermal processing of microstructure and properties under controllable deformation conditions.

[0025] Reference Figure 1-5 The present invention mainly includes the following steps:

[0026] Step 1, Mold Upsetting: The mold has a vertically oriented, rotationally symmetrical cavity running along its axis. Along the longitudinal direction, it includes a first through hole, a second through hole, a third through hole, and an ejector through hole located below the third through hole, all with gradually decreasing dimensions. The sides of the first and second through holes have draft angles. The inner diameter of the first through hole is larger than the outer diameter of the large end of the forging. The height of the first through hole is one-third to one-quarter of the forging's height. The inner diameter of the second through hole is smaller than the outer diameter of the small end of the forging. The sum of the heights of the first and second through holes is less than the axial height of the forging.

[0027] Preferably, the height of the second through hole is one-third of the height of the forging.

[0028] This step reduces the height of the bar stock. Considering that the part that first contacts the mold during the upsetting process cools faster and has the smallest deformation, it is easy to form a deformation dead zone. The upper positioning platform of the upsetting ejector plate has the same shape as the positioning platform of the pre-forging ejector plate. The axial height of the second step of the upsetting ejector plate is two-thirds of the height of the second through hole of the mold, which is to reserve deformation space for pre-forming. The deformation of the large deformation area during upsetting is 50% to 75%, and the deformation of the small deformation area on the outer edge of the lower end face is 20% to 35%.

[0029] The lower section of the upsetting ejector plate has the same shape as the third through hole, the middle section has the same shape as the lower part of the second through hole, and the upper end face is provided with a first positioning platform; the height of the first positioning platform is greater than the height of the second through hole.

[0030] The lower section of the preformed ejector plate has the same shape as the third through hole, and a second positioning platform is provided on the upper end face; the minimum distance between the second positioning platform and the upper end face of the mold is 35-45mm.

[0031] Based on past production experience, when the thickness of GH4169 is pressed to below 30mm, the deformation resistance will increase instantly, and the thickness cannot be pressed down further. Therefore, the thickness of the center part of the preformed ejector plate is controlled at 35-45mm.

[0032] First, using a mold for upsetting, a φ250-300mm high bar with pre-machined positioning holes is heated to its deformation temperature. After heat preservation, it is placed on a mold with an upsetting ejector plate installed (e.g., ...). Figure 2 The upper mold is a flat mold. The initial parting distance H1 is equal to h minus the height of the first through hole of the mold. First, press it at an initial speed of 7mm / s-8mm / s to one-half to two-thirds of the difference between the initial parting distance H1 and the reserved height A; then press it at 4mm / s to the reserved height A. After air cooling for 10 minutes, return it to the furnace for reheating.

[0033] Because the forging is large in size, the deformation resistance gradually increases during the upsetting process as the billet cools and the reduction increases. The pressing speed is fast at first and then slows down. This not only reduces the cracking of the billet during the pressing process, but also improves the deformation heat generated inside the billet during the pressing process, improves the internal and external temperature field of the forging, and helps to ensure the microstructure and properties of the forging.

[0034] The second step is pre-forming the mold, replacing the pre-forming ejector plate, and after the forging is heat-insulated, placing the forging on the pre-forming mold (e.g., ...). Figure 3 The initial parting surface distance H2 is first pressed at an initial speed of 5 mm / s to one-third of the initial parting surface distance H2, and then pressed at 3 mm / s to 2 mm.

[0035] In this step, the pre-formed, upset billet can be directly placed on this ejector plate for excellent positioning. During this pressing process, the billet metal flows synchronously in the axial and radial directions, further increasing the deformation at the bottom of the billet. This pre-forming ejector plate, while forming and distributing the material, also creates a punching effect on the dead zone in the core during the upsetting process. The overall deformation of the billet is uniform, distributed across 45%-75%, and the small deformation zone at the bottom is significantly improved, with deformation reaching 30%-45%.

[0036] The third step is rough machining, such as... Figure 3 The cold die layer and core skin are removed during machining to reduce the impact of the deformation dead zone during the forging process. In die forging, the machined rough shape is heated to the deformation temperature, held at that temperature, and then placed on a forging die (e.g., ...). Figure 4 First, press the die at an initial speed of 7 mm / s to two-thirds of the forging depth, then press at 3 mm / s to a distance of 6 mm from the parting surface, then use air cooling to finish the forging process.

[0037] Because of the use of molds and sufficient pre-forming deformation, the removal of local cold mold layers through machining is beneficial to improving the forging performance and reducing the impact of residual structures due to uneven deformation in the previous process on the forging. During the forging process, the internal and external temperature fields of the forging are adjusted by first reducing the deformation speed and then increasing it, so as to achieve a good match between the temperature field and the strain of each part of the forging, resulting in a uniform and standard-compliant forging.

[0038] Example:

[0039] The technical solution of the present invention will be further described in detail below with reference to the embodiments:

[0040] Preparation of large GH4169 alloy conical disc forgings, such as Figure 1 As shown, the forging has an outer diameter of φ628mm, an axial dimension of 259mm, and a projected area of ​​approximately 0.31m². 2 .

[0041] The forging process is detailed below:

[0042] The first step involves using the designed mold and upsetting ejector plate, such as... Figure 2 The selected bar stock is placed on the lower die by bottom positioning. Upsetting is achieved by using an upper flat die and a lower punch to compress the center of the bar stock. The pressing stops at a distance of 115mm from the parting surface, leaving room for deformation in various parts of the preformed forging.

[0043] The second step involves using the designed mold and pre-formed ejector plate, such as... Figure 3 The positioning holes pressed by the upsetting ejector plate and the positioning platform of the ejector plate achieve good positioning, allowing the undeformed deformation dead zone to continue to participate in deformation, achieving synchronous deformation of the edge and core. The purpose of this step is to ensure uniform deformation of all parts of the pre-formed forging and improve the deformation consistency of the microstructure.

[0044] The third step involves machining a cold mold layer and a positioning table to form the final forging die in one pass. Variable speed pressing is used to reduce the deformation dead zone and also to reduce the equipment tonnage, which is 18,000t to 20,000t.

[0045] The forging process requires three heat treatments to ensure uniform microstructure. Tests show that the forging performance meets the specifications and does not exhibit defects such as mixed crystals caused by uneven forging deformation. This greatly improves upon the problem that traditional forming methods cannot meet the tonnage requirements of forging equipment, while also ensuring stable and reliable performance indicators.

Claims

1. A process for preforming a large high-temperature alloy conical disc mold blank, characterized in that, include: The first step is upsetting the mold: The mold has a vertically oriented, rotationally symmetrical cavity running along its axis. Along its longitudinal direction, it includes a first through hole, a second through hole, a third through hole, and an ejector through hole located below the third through hole. The inner diameter of the first through hole is larger than the outer diameter of the large end of the final forging; the inner diameter of the second through hole is smaller than the outer diameter of the small end of the final forging; the sum of the heights of the first and second through holes is less than the axial height of the final forging; the lower section of the upsetting ejector plate has the same shape as the third through hole, and the middle section has the same shape as the lower part of the second through hole, with a first positioning platform on its upper surface; the height of the first positioning platform is greater than the height of the second through hole; the lower section of the pre-forming ejector plate has the same shape as the third through hole, with a second positioning platform on its upper surface. First, the bar stock with a height of h and a φ250mm-φ300mm and pre-machined positioning holes is heated to the deformation temperature by upsetting with a mold. After heat preservation, it is placed on the mold with the upsetting ejector plate installed. The upper mold is a flat mold. The initial mold parting distance H1 is equal to the bar stock height h minus the height of the first through hole of the mold. The bar stock is pressed down to the reserved height A with a gradually decreasing pressing speed. After air cooling for 10 minutes, it is returned to the furnace for reheating. The second step is preforming the mold: After replacing the preforming ejector plate, the forging after the mold upsetting is completed and the heat is maintained, it is placed on the preforming mold with an initial parting surface distance of H2. The bar is pressed down to a parting surface distance of 2mm with a gradually decreasing pressing speed. Step 3: Die forging: Heat the processed rough die to the deformation temperature. After heat preservation, place the rough die on the final forging die and press it down at a gradually decreasing speed until the parting surface is 6mm away. Then, use air cooling.

2. The process method for preforming a large high-temperature alloy conical disc mold blank according to claim 1, characterized in that, The sides of the first through hole, the second through hole, and the third through hole have draft angles.

3. The process method for preforming a large high-temperature alloy conical disc mold blank according to claim 1, characterized in that, The height of the first through hole is one-third to one-quarter of the final forging height.

4. The process method for preforming a large high-temperature alloy conical disc mold blank according to claim 1, characterized in that, The minimum distance between the second positioning platform and the upper surface of the mold is 35-45mm.

5. The process method for preforming a large high-temperature alloy conical disc mold blank according to claim 1, characterized in that, During the upsetting process, the bar stock is pressed down to the reserved height A at a gradually decreasing pressing speed. Specifically, it is pressed down to one-half to two-thirds of the difference between the initial parting distance H1 and the reserved height A at an initial speed of 7 mm / s to 8 mm / s; then pressed down to the reserved height A at 4 mm / s, air-cooled for 10 minutes, and then reheated in the furnace.

6. The process method for preforming a large high-temperature alloy conical disc mold blank according to claim 1, characterized in that, During the pre-forming process of the mold, the bar stock is pressed down to a distance of 2mm from the parting surface at a gradually decreasing pressing speed. Specifically, this includes: First, press at an initial speed of 5 mm / s to one-third of the initial parting surface distance H2, then press at 3 mm / s to 2 mm of the parting surface distance.

7. The process method for preforming a large high-temperature alloy conical disc mold blank according to claim 1, characterized in that, The third step, before die forging, also includes: machining to remove the cold die layer and core skin of the rough mold.

8. The process method for preforming a large high-temperature alloy conical disc mold blank according to claim 1, characterized in that, In the third step, the pressure is gradually reduced until the parting surface is 6mm away, and air cooling is provided. Specifically, the pressure is first reduced to three-quarters of the forging pressure at an initial speed of 7mm / s, and then reduced to 6mm away at 3mm / s, and air cooling is provided.

Images