Large frame type aluminum alloy product and preparation method thereof

Abstract

The invention relates to the technical field of frame type aluminum alloy preparation, and particularly discloses a preparation method of a large frame type aluminum alloy product, and the preparation method comprises the following steps: pretreatment: preparing a support ring and a support template for later use; the aluminum alloy cast ingot is machined into a ring piece; remelting and heating: forming a nested part in the support ring part, and remelting and heating the nested part; frame forging is conducted, specifically, the nesting piece subjected to remelting heating treatment is transferred to a forging and pressing platform, the supporting templates are symmetrically arranged on the two sides of the nesting piece, the nesting piece and the supporting templates form a combined die, and a mandrel penetrates through the combined die and can drive the combined die to rotate; in the forging process, the combined module rotates to replace the forging surface, and forging is performed until the ring piece is formed into a frame piece; and heat treatment is conducted, specifically, the frame part is taken out, and the frame-type aluminum alloy product is obtained after heat treatment. The production efficiency is high, the cost is low, and the prepared frame type aluminum alloy product is good in mechanical property and excellent in overall performance and can better meet the requirements of aerospace on aluminum alloy frame pieces.

Description

Technical Field

[0001] The present invention relates to the technical field of frame-type aluminum alloy preparation, and in particular to a large-scale frame-type aluminum alloy product and a preparation method thereof. Background Art

[0002] Alloy frames exceeding 3 meters in length and width are considered ultra-large, load-bearing components and are crucial aircraft structural components. They are typically fabricated from high-strength aluminum alloys to meet the stringent requirements for structural strength, lightweighting, and reliability. The current mainstream processing method in the industry is sheet blanking followed by CNC milling, but this technology has significant limitations: First, material utilization is low. Because a large amount of redundant material must be removed from the entire sheet during milling, the actual material utilization rate is less than 10%, resulting in significant resource waste. Second, there are production efficiency bottlenecks. The milling process requires multiple, high-precision passes for ultra-large sheet materials, resulting in lengthy production cycles that are difficult to meet the efficient delivery requirements of modern aviation manufacturing. Furthermore, cost control challenges, combined with low material utilization and long processing cycles, directly drive up the overall manufacturing cost of the product and limit its potential for large-scale application. Furthermore, during milling, the material's original deformation streamlines do not align with the actual structural shape of the part, resulting in significant disruption of streamlines. This issue directly reduces the actual performance allowable value of the part, significantly limiting its performance and potential for improvement during service.

[0003] Conventional forging processes for these large frame components present complex process flows and can easily cause uneven local deformation at the four corners during forming, leading to low elongation and poor overall performance. Currently available technical solutions, including 3D printing, can precisely form large frame parts, but their performance still falls short of the requirements for load-bearing structural components, particularly those used in aerospace applications. Therefore, the production and processing of these large alloy frame products urgently needs improvement. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a method for preparing large-scale frame-type aluminum alloy products, so as to further improve the comprehensive performance of large-scale frame-type aluminum alloy products while increasing production efficiency and reducing costs.

[0005] The technical problem solved by the present invention is also to provide a large-scale frame-type aluminum alloy product with excellent comprehensive performance to better meet the needs of aerospace components.

[0006] The technical problem solved by the present invention is achieved by adopting the following technical solutions: A method for preparing a large frame-type aluminum alloy product comprises the following steps: Pretreatment: Prepare support rings and support templates for standby use; process aluminum alloy ingots into rings; Reheating: placing the cold support ring in the hot ring to form a nested part, and reheating the nested part to make the expansion of the support ring greater than the thermal expansion of the ring to form an interference fit and generate radial compressive stress; Forging frame: The nested parts that have been reheated are transferred to the forging platform. The support templates are symmetrically arranged on both sides of the nested parts. The nested parts and the support templates form a combined die. The mandrel passes through the combined die and can drive the combined die to rotate. During the forging process, the combined die rotates to replace the forging surface. The forging is carried out until the ring is formed into a frame and the inner edge of the frame is flush with the edge of the support template. Heat treatment: The frame is taken out and subjected to heat treatment to obtain a frame-type aluminum alloy product.

[0007] Furthermore, in the pretreatment step, the thickness of the support ring is kept consistent with that of the ring member.

[0008] Furthermore, in the preprocessing step, the ratio of the outer diameter of the ring to the outer diagonal length of the frame is 1~1.05:1; the ratio of the inner diameter of the ring to the inner frame diagonal length of the frame is 0.95~1:1; the outer diameter of the support ring matches the inner diameter of the ring; the length and width of the support template are respectively consistent with the length and width of the inner frame of the frame.

[0009] Furthermore, in the pretreatment step, the support ring is made of aluminum alloy ingot or aluminum alloy forging, and the support template is die steel.

[0010] Furthermore, in the pretreatment step, the aluminum alloy ingot is heated to 440-480° C. and kept warm for 10-14 hours, subjected to multi-directional forging to open the blank, punched, and then ring rolled to obtain a ring.

[0011] Furthermore, in the reheating step, the nested parts are reheated at 440-480° C. for heat preservation. When the temperature of the support ring rises to 320-380° C., the reheating is completed.

[0012] Furthermore, the interference fit between the support ring and the ring member is 0.7-0.9%.

[0013] Furthermore, the frame-type aluminum alloy product is a 2050 aluminum alloy frame or a 7050 aluminum alloy frame.

[0014] Furthermore, the length and width of the frame-type aluminum alloy product are both greater than or equal to 3000 mm.

[0015] Furthermore, in the frame forging step, the forging is performed by using a flat anvil and single-sided pressing method.

[0016] A large frame-type aluminum alloy product is prepared by any of the above methods, and has a tensile strength greater than 560 MPa, a yield strength greater than 520 MPa, and an elongation greater than 10.5%.

[0017] Beneficial effects: The method for preparing large-scale frame-type aluminum alloy products described in the present invention uses ring rolling to produce a ring with continuous streamlines, and then forms an interference fit by nesting a cold support ring with a hot ring, and then the mosaic and the support template together form a combined die. During forging, a single-sided forging method combined with rotary continuous forging is used to solve the problems of low performance, low production efficiency, and high cost of existing large-scale frame-type aluminum alloy products. The preparation process of the present invention is simple, the production efficiency is high, and the material utilization rate is high. Compared with the traditional process of plate blanking and CNC milling, the material utilization rate of the present invention is increased from the traditional 15% to 65%. At the same time, the processing cycle of a single piece is shortened from the traditional at least 15 days to within seven days, which has good practical promotion and application value.

[0018] The frame-type aluminum alloy products prepared by the present invention have good mechanical properties, a tensile strength greater than 560 MPa, a yield strength greater than 520 MPa, uniform local deformation of the four corners of the square frame, an elongation greater than 10.5%, and excellent overall performance, which can better meet the aerospace demand for aluminum alloy frames. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the combined die in the frame forging step of the present invention.

[0020] Figure 2 Schematic diagram of the structure of the nested parts in the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of the frame-type aluminum alloy product of the present invention.

[0022] Figure 4 This is the metallographic structure diagram of the corner of the aluminum alloy frame in Example 1 of the present invention.

[0023] Figure 5 This is the metallographic structure diagram of the corner of the aluminum alloy frame in Example 2 of the present invention.

[0024] Figure 6 This is the metallographic structure diagram of the corner of the aluminum alloy frame in comparative example 1 of the present invention.

[0025] Figure 7 This is the metallographic structure diagram of the corner of the aluminum alloy frame in Comparative Example 2 of the present invention.

[0026] Among them: 1. Ring; 2. Support ring; 3. Core shaft; 4. Bolt assembly; 5. Support template; 6. Positioning block. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below with reference to specific embodiments.

[0028] Example 1

[0029] The method for preparing a large-scale frame-type aluminum alloy product of the present invention is a 2050 aluminum alloy frame; the preparation method comprises the following steps: Preprocessing: Use scrapped aluminum alloy forgings to process into a support ring 2 with a diameter of 3650mm, a thickness of 150mm, and an inner hole diameter of 400mm for standby use; Two support templates 5 are made of 5CrNiMo alloy steel. The length and width of the support template 5 are both 2600 mm and the thickness is 80 mm. There is a through hole in the center of the support template 5, which matches the inner hole of the support ring 2. The aluminum alloy ingot was heated to 460° C. in a heating furnace and kept warm for 12 hours. After the holding was completed, multi-directional forging was performed to open the blank. After the blank was opened, it was kept warm at 460° C. for 4 hours, and then punched and ring rolled to obtain a ring 1 with an outer diameter of 4250 mm.

[0030] Reheating: The cold support ring 2 at room temperature is placed inside the hot ring 1 to form a nested part. The nested part structure is as follows: Figure 2 As shown, the nested parts are returned to the furnace and kept warm at 460°C; the temperature of the support ring 2 blank is monitored. When the temperature reaches 350°C, the expansion of the support ring 2 is greater than the thermal expansion of the ring 1, forming an interference fit to generate radial compressive stress. At this time, the interference fit range is 0.7~0.9%.

[0031] Forging frame: transfer the nested parts after the reheating treatment to the forging platform, and set the support template 5 symmetrically on both sides of the nested parts. The nested parts and the support template 5 form a combined mold. The combined mold structure is as follows: Figure 1 As shown, the nested part and the support template 5 are fixed by the positioning block 6 and the bolt assembly 4. The core shaft 3 passes through the combined die and can drive the combined die to rotate under the action of external force. The flat anvil single-sided pressing method is adopted. During the forging process, the ring 1 and the support ring 2 with interference fit with the ring 1 are deformed at the same time. During the forging process, the combined die can be rotated in sequence to replace the forging surface. The forging is carried out until the ring 1 is formed into a frame and the inner frame edge of the frame is flush with the edge of the support template. The frame structure is shown in FIG. Figure 3 As shown, the frame dimensions are 3000mm×3000mm on the outside, 2600mm×2600mm on the inside, and 150mm in thickness.

[0032] Heat Treatment: The frame is removed and heated to 510°C for 5 hours. After this, it is quenched in room temperature water and cold-deformed, with the bulging controlled to 3%. After cold deformation, it is aged at 145°C for 40 hours. This completes the heat treatment to produce the aluminum alloy frame product.

[0033] The metallographic structure of the corner of the aluminum alloy frame prepared in this embodiment is as follows: Figure 4 shown.

[0034] Example 2 The method for preparing a large-scale frame-type aluminum alloy product of the present invention is a 7050 aluminum alloy frame; the preparation method comprises the following steps: Preprocessing: Use scrapped aluminum alloy forgings to process into a support ring 2 with a diameter of 3650mm, a thickness of 150mm, and an inner hole diameter of 400mm for standby use; Two support templates 5 are made of 5CrNiMo alloy steel. The length and width of the support template 5 are both 2600 mm and the thickness is 80 mm. There is a through hole in the center of the support template 5, which matches the inner hole of the support ring 2. The aluminum alloy ingot was heated to 450°C in a heating furnace and kept warm for 12 hours. After the holding was completed, multi-directional forging was performed to open the blank. After the blank was opened, it was kept warm at 450°C for 4 hours, and then punched and ring rolled to obtain a ring 1 with an outer diameter of 4250 mm.

[0035] Reheating: The cold support ring 2 at room temperature is placed inside the hot ring 1 to form a nested part. The nested part structure is as follows: Figure 2 As shown, the nested parts are returned to the furnace and kept warm at 450°C; the temperature of the support ring 2 blank is monitored. When the temperature reaches 320°C, the expansion of the support ring 2 is greater than the thermal expansion of the ring 1, forming an interference fit to generate radial compressive stress. At this time, the interference fit range is 0.7~0.9%.

[0036] Forging frame: transfer the nested parts after the reheating treatment to the forging platform, and set the support template 5 symmetrically on both sides of the nested parts. The nested parts and the support template 5 form a combined mold. The combined mold structure is as follows: Figure 1 As shown, the nested part and the support template 5 are fixed by the positioning block 6 and the bolt assembly 4. The core shaft 3 passes through the combined die and can drive the combined die to rotate under the action of external force. The forging is carried out by the flat anvil unilateral pressing method. During the forging process, the ring 1 and the support ring 2 with interference fit with the ring 1 are deformed at the same time. During the forging process, the combined die can be rotated in sequence to replace the forging surface. The forging is carried out until the ring 1 is formed into a frame, and the inner frame edge of the frame is flush with the edge of the support template. The frame structure is as shown in FIG. Figure 3As shown, the frame dimensions are 3000mm×3000mm on the outside, 2600mm×2600mm on the inside, and 150mm in thickness.

[0037] Heat Treatment: The frame is removed and heated to 475°C for 5 hours. After this, it is quenched in room temperature water and cold-deformed, with the bulging controlled to 1.5%. After cold deformation, it is aged at 120°C for 8 hours, followed by 160°C for 12 hours. This completes the heat treatment process to produce the aluminum alloy frame product.

[0038] The metallographic structure of the corner of the aluminum alloy frame prepared in this embodiment is as follows: Figure 5 shown.

[0039] Comparative Example 1 The large frame aluminum alloy product described in this comparative example is a 7050 aluminum alloy frame; its preparation method comprises the following steps: Preprocessing: Use scrapped aluminum alloy forgings to process into a support ring 2 with a diameter of 3650mm, a thickness of 150mm, and an inner hole diameter of 400mm for standby use; Two support templates 5 are made of 5CrNiMo alloy steel. The length and width of the support template 5 are both 2600 mm and the thickness is 80 mm. There is a through hole in the center of the support template 5, which matches the inner hole of the support ring 2. The aluminum alloy ingot was heated to 450°C in a heating furnace and kept warm for 12 hours. After the holding was completed, multi-directional forging was performed to open the blank. After the blank was opened, it was kept warm at 450°C for 4 hours, and then punched and ring rolled to obtain a ring 1 with an outer diameter of 4250 mm.

[0040] Reheating: The cold support ring 2 at room temperature is placed inside the hot ring 1 to form a nested part. The nested part structure is as follows: Figure 2 As shown, the nested parts are returned to the furnace and kept warm at 450°C; the temperature of the support ring 2 blank is monitored, and when the temperature reaches 260°C, the next step is carried out.

[0041] Forging frame: transfer the nested parts after the reheating treatment to the forging platform, and set the support template 5 symmetrically on both sides of the nested parts. The nested parts and the support template 5 form a combined mold. The combined mold structure is as follows: Figure 1 As shown, the nested part and the support template 5 are fixed by the positioning block 6 and the bolt assembly 4. The core shaft 3 passes through the combined die and can drive the combined die to rotate under the action of external force. The forging is carried out by the flat anvil unilateral pressing method. During the forging process, the ring 1 and the support ring 2 with interference fit with the ring 1 are deformed at the same time. During the forging process, the combined die can be rotated in sequence to replace the forging surface. The forging is carried out until the ring 1 is formed into a frame, and the inner frame edge of the frame is flush with the edge of the support template. The frame structure is as shown in FIG. Figure 3As shown, the frame dimensions are 3000mm×3000mm on the outside, 2600mm×2600mm on the inside, and 150mm in thickness.

[0042] Heat Treatment: The frame is removed and heated to 475°C for 5 hours. After this, it is quenched in room temperature water and cold-deformed, with the bulging controlled to 1.5%. After cold deformation, it is aged at 120°C for 8 hours, followed by 160°C for 12 hours. This completes the heat treatment process to produce the aluminum alloy frame product.

[0043] The metallographic structure of the corner of the aluminum alloy frame prepared in this comparative example is as follows: Figure 6 shown.

[0044] Comparative Example 2 The large frame aluminum alloy product described in this comparative example is a 7050 aluminum alloy frame; its preparation method comprises the following steps: Preprocessing: Use scrapped aluminum alloy forgings to process into a support ring 2 with a diameter of 3650mm, a thickness of 150mm, and an inner hole diameter of 400mm for standby use; Two support templates 5 are made of 5CrNiMo alloy steel. The length and width of the support template 5 are both 2600 mm and the thickness is 80 mm. There is a through hole in the center of the support template 5, which matches the inner hole of the support ring 2. The aluminum alloy ingot was heated to 450°C in a heating furnace and kept warm for 12 hours. After the holding was completed, multi-directional forging was performed to open the blank. After the blank was opened, it was kept warm at 450°C for 4 hours, and then punched and ring rolled to obtain a ring 1 with an outer diameter of 4250 mm.

[0045] Reheating: The cold support ring 2 at room temperature is placed inside the hot ring 1 to form a nested part. The nested part structure is as follows: Figure 2 As shown, the nested parts are returned to the furnace and kept warm at 450°C; the temperature of the support ring 2 blank is monitored. When the temperature reaches 320°C, the expansion of the support ring 2 is greater than the thermal expansion of the ring 1, forming an interference fit to generate radial compressive stress. At this time, the interference fit range is 0.7~0.9%.

[0046] Forging frame: transfer the nested parts after the reheating treatment to the forging platform, and set the support template 5 symmetrically on both sides of the nested parts. The nested parts and the support template 5 form a combined mold. The combined mold structure is as follows: Figure 1As shown, the nested part and the support template 5 are fixed by the positioning block 6 and the bolt assembly 4. The core shaft 3 passes through the combined die and can drive the combined die to rotate under the action of external force. The forging is carried out by single-sided segmented pressing of the flat anvil. During the forging process, the ring 1 and the support ring 2 with interference fit with the ring 1 are deformed at the same time. During the forging process, the combined die can be rotated in sequence to replace the forging surface. The forging is carried out until the ring 1 is formed into a frame, and the inner frame edge of the frame is flush with the edge of the support template. The frame structure is as shown in FIG. Figure 3 As shown, the frame dimensions are 3000mm×3000mm on the outside, 2600mm×2600mm on the inside, and 150mm in thickness.

[0047] Heat Treatment: The frame is removed and heated to 475°C for 5 hours. After this, it is quenched in room temperature water and cold-deformed, with the bulging controlled to 1.5%. After cold deformation, it is aged at 120°C for 8 hours, followed by 160°C for 12 hours. This completes the heat treatment process to produce the aluminum alloy frame product.

[0048] The metallographic structure of the corner of the aluminum alloy frame prepared in this comparative example is as follows: Figure 7 shown.

[0049] Comparative Example 3 This control example adopts the traditional plate cutting and CNC milling method for processing. The dimensions of the 7050 aluminum alloy frame prepared are 3000mm×3000mm for the outer dimension, 2600mm×2600mm for the inner dimension, and 150mm for the thickness.

[0050] The lowest performance values ​​at the corners of the aluminum alloy frames prepared in Examples 1-2 and Comparative Examples 1-3 were tested according to the tensile test of metal materials in accordance with GBT / 228.1-2021. The results are shown in Table 1.

[0051]

[0052] As shown in Table 1, the aluminum alloy frame prepared by the present invention has a high elongation at the corner of the frame and good mechanical properties. Figures 4-7 From the metallographic organization diagram analysis, it can be seen that the fine grain structure of the aluminum alloy frame prepared by the present invention is evenly distributed along the deformation direction, while there is a phenomenon of local grain unevenness in both control examples 1 and 2, which is presumably caused by the uneven deformation mode.

[0053] In traditional similar horse forging processes, segmented local forging deformation is mostly used, which easily causes the destruction of the original deformation streamline of the ring, resulting in uneven organization and uneven grain distribution in the product. At the same time, for the semi-closed mold system used in this method, segmented local forging will lead to uncontrollable dimensions. However, the present invention creatively adopts the combination of support template and support ring. If combined with segmented local forging, as shown in Comparative Example 2 and Appendix Figure 7 The present invention adopts the support template and the support ring to meet the conditions for full pressing and combines them with the full pressing process, so that the internal structure of the prepared product can be uniform and the overall size can be controlled.

[0054] In addition, compared with the traditional plate cutting and CNC milling method in Control Example 3, the mechanical properties of the aluminum alloy frame prepared by the present invention are improved, and the material utilization rate can be increased from the traditional 15% to 65%, an increase of about 50%, and the material cost is greatly reduced. At the same time, the single-piece processing cycle is shortened from the traditional more than 15 days to less than 7 days, and the production efficiency is greatly improved.

[0055] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a large frame-type aluminum alloy product, characterized in that: The steps include: Pretreatment: Prepare support rings and support templates for standby use; process aluminum alloy ingots into rings; Reheating: placing the cold support ring in the hot ring to form a nested part, and reheating the nested part to make the expansion of the support ring greater than the thermal expansion of the ring to form an interference fit and generate radial compressive stress; Forging frame: The nested parts that have been reheated are transferred to the forging platform. The support templates are symmetrically arranged on both sides of the nested parts. The nested parts and the support templates form a combined die. The mandrel passes through the combined die and can drive the combined die to rotate. The forging is carried out by using a flat anvil single-sided pressing method. During the forging process, the combined die rotates to replace the forging surface. The forging is carried out until the ring is formed into a frame and the inner edge of the frame is flush with the edge of the support template. Heat treatment: The frame is taken out and subjected to heat treatment to obtain a frame-type aluminum alloy product.

2. The method for preparing a large frame-type aluminum alloy product according to claim 1, wherein: In the pretreatment step, the thickness of the support ring is kept consistent with that of the ring member.

3. The method for preparing a large frame-type aluminum alloy product according to claim 1, wherein: In the preprocessing step, the ratio of the outer diameter of the ring to the outer diagonal length of the frame is 1~1.05:1; the ratio of the inner diameter of the ring to the inner frame diagonal length of the frame is 0.95~1:1; the outer diameter of the support ring matches the inner diameter of the ring; the length and width of the support template are respectively consistent with the length and width of the inner frame of the frame.

4. The method for preparing a large frame-type aluminum alloy product according to claim 1, wherein: In the pretreatment step, the support ring is made of aluminum alloy ingot or aluminum alloy forging, and the support template is mold steel.

5. The method for preparing a large frame-type aluminum alloy product according to claim 1, wherein: In the pretreatment step, the aluminum alloy ingot is heated to 440-480°C and kept warm for 10-14 hours, multi-directional forging is performed to open the blank, punching is performed, and then ring rolling is performed to obtain a ring.

6. The method for preparing a large frame-type aluminum alloy product according to claim 1, wherein: In the reheating step, the nested parts are reheated at 440-480°C for heat preservation. When the temperature of the support ring rises to 320-380°C, the reheating is completed.

7. The method for preparing a large frame-type aluminum alloy product according to claim 6, characterized in that: The interference fit between the support ring and the ring member is 0.7-0.9%.

8. The method for preparing a large frame-type aluminum alloy product according to claim 1, wherein: The frame-type aluminum alloy product is a 2050 aluminum alloy frame or a 7050 aluminum alloy frame; the length and width dimensions of the frame-type aluminum alloy product are both greater than or equal to 3000 mm.

9. Large frame aluminum alloy products, characterized in that: The composite material is prepared by the method according to any one of claims 1 to 8, and has a tensile strength greater than 560 MPa, a yield strength greater than 520 MPa, and an elongation greater than 10.5%.

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