Bulging method for large aluminum alloy annular forgings

Abstract

The invention relates to a bulging method for a large aluminum alloy annular forge piece, in particular to a method for eliminating residual stress of the large annular forge piece by adding a cold bulging procedure and increasing the temperature of a solid solution medium. According to the method, water at the temperature of 85 DEG C or above is used as a solid solution medium, the fluidity of the solid solution medium is improved, and the residual stress level of the ring forging is reduced. And cold bulging is carried out within 2 hours after solid solution, and the bulging deformation is controlled to be 2%. The residual stress level is reduced; and the stress distribution is improved. It is guaranteed that the ring forgings do not deform during machining, and the product percent of pass is increased. The method for eliminating the residual stress is mainly used for machining large ring forgings in the fields of aviation, aerospace, weaponry, industrial machinery and the like.

Description

Technical Field:

[0001] The present invention relates to a method for bulging a ring-shaped part, and particularly to a method for bulging a large aluminum alloy ring forging. Background Art:

[0002] The casing ring forging is an important type of part in an aeroengine, and is usually machined from a blank ring forging provided by a forging factory. The new engine 2A70 aluminum alloy casing parts are a common type of large ring forgings, and often deform during machining, resulting in scrapping of the parts. Relevant data shows that an important factor causing part machining deformation is the excessive internal residual stress in the blank ring forging. Reducing the internal residual stress of the blank ring forging can effectively alleviate the deformation caused by the release of residual stress during the machining process of the part. In the production process of such parts, the residual stress is often eliminated by means of ring tying, solution treatment and then aging treatment of the blank ring forging. However, in actual production, there is still a relatively high residual stress in the blank ring forging after the above-mentioned processes.

[0003] The Chinese invention patent CN102489590A published on June 13, 2012 discloses a cold bulging method for an aluminum alloy ring forging. As shown in the attached drawings of this specification, Figure 1 this method is to sleave the cold-rolled aluminum alloy rectangular ring forging 4 around the periphery of the bulging block 3, and start the bulging machine to extrude the ring rolling part from the inner circumferential surface of the ring rolling part along the radial direction to complete the bulging. Through this method, the dimensional accuracy of the ring rolling part can be effectively improved. However, this patent only simply expounds the function of the cold bulging process in improving the dimensional accuracy of the ring rolling part, and does not disclose the cold stretching essence of the cold bulging process and the function of eliminating the residual stress of the ring rolling part. Summary of the Invention:

[0004] The technical problem to be solved by the present invention is to provide a method for eliminating the residual stress of a large aluminum alloy ring rolling part, that is, adding a cold bulging step between the solution and aging steps and increasing the solution medium temperature to achieve the purpose of eliminating the residual stress of the large ring forging.

[0005] To solve the above problems, the present invention provides a method for bulging a large aluminum alloy ring forging. The steps are as follows:

[0006] Cut the aluminum alloy bar into a certain specification. After heating the heating furnace to 450 ± 10 °C, put the aluminum alloy bar into the heating furnace and keep it warm for 12 hours; then transfer the heat-preserved aluminum alloy bar to the press, and the transfer time is less than 50 seconds; upset the blank to H on the press, the deformation process takes about 13 s, and the downward pressing speed of the upper pressing block is 30 mm / s to 40 mm / s; use a punch to punch a blind hole, the press presses the whole punch into the blank, and after punching the blind hole, turn the forging over so that the blind hole with the punch faces down and place it on the drain pan to punch a through hole until the aluminum alloy ring blank is obtained;

[0007] Adopt multi-pass rolling. For the first pass, heat the punched aluminum alloy ring blank back to the furnace while it is still hot, keep it at 450 ± 10 °C for 6 hours, and roll it on the ring rolling machine. The dimensional requirements are Ф670 ± 10 × Ф370 ± 10 × Hmm, and level the height to H = 270 ± 5 mm; for the second pass, heat the aluminum alloy ring blank back to the furnace while it is still hot, keep it at 450 ± 10 °C for 6 hours, and roll it on the ring rolling machine. The dimensional requirements are Ф904 ± 10 × Ф704 ± 10 × Hmm, and level the height to H = 265 ± 5 mm; for the third pass, heat the aluminum alloy ring blank back to the furnace while it is still hot, keep it at 450 ± 10 °C for 6 hours, roll it on the ring rolling machine. The dimensional requirements are Ф1218 ± 10 × Ф1078 ± 10 × Hmm, and level the height to H = 260 ± 5 mm; for the fourth pass, heat the aluminum alloy ring blank back to the furnace while it is still hot, keep it at 450 ± 10 °C for 6 hours, and perform the final rolling on the ring rolling machine. The dimensional requirements are Ф1490 ± 5 × Ф1378 ± 5 × 247 ± 5 mm, and level the height to H = 260 ± 5 mm; thus obtaining the aluminum alloy ring rolled piece.

[0008] After heating the heating furnace to 530 ± 5 °C, load the aluminum alloy ring rolled piece after final rolling into the heating furnace and keep it for 3 hours, then cool it in hot water at a temperature higher than 85 °C for 15 minutes, and then transfer it to a cold water tank to cool it to room temperature.

[0009] Put the aluminum alloy ring rolled piece after solution treatment on the periphery of the bulging block of the bulging machine. At room temperature, start the bulging machine to apply a downward force F on the mandrel to make it move downward, thereby driving the radial slider and the bulging block to perform radial movement. At the same time, apply an axial pressure F2 to the lower pressing ring to ensure that the axial dimension of the ring forging does not change; the bulging deformation of the aluminum alloy ring rolled piece is controlled within 2%. After cold bulging, the dimensions of the ring forging are Ф1518 ± 2 × Ф1408 ± 2 × 247 ± 6 mm, obtaining the aluminum alloy ring piece.

[0010] Perform aging treatment on the bulged aluminum alloy ring piece. Load the aluminum alloy ring piece into the heating furnace, heat it up to 170 - 200 °C along with the furnace, and keep it for 13 hours; take out the aluminum alloy ring piece and cool it by dispersing in the air.

[0011] Furthermore, the specification of the aluminum alloy bar is Ф400 × 572 mm.

[0012] Furthermore, during the upsetting process, upset the blank to H = 280 mm.

[0013] Furthermore, the specification of the punch is Ф185 mm.

[0014] Furthermore, the aging treatment is carried out within 4 hours after the solution treatment.

[0015] Furthermore, the aluminum alloy is 2A70 alloy.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] In the method for bulging a large aluminum alloy ring forging of the present invention, since the solution medium temperature is increased, the fluidity of water is increased (viscosity is reduced), the temperature uniformity during solution cooling of the ring forging is improved, and the residual stress level is reduced to a certain extent. At the same time, cold bulging is carried out within 2 hours after solution treatment, and the bulging deformation amount is controlled at 2%. Cold bulging is used to adjust the residual stress inside the ring forging, reducing the residual stress level and improving the stress distribution. It ensures that the ring forging does not deform during machining and improves the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0019] Figure 1 It is a schematic diagram of the cold bulging process.

[0020] Figure 2 It is a cross-sectional view of a large ring forging. SPECIFIC EMBODIMENTS

[0021] To implement the method for bulging a large aluminum alloy ring forging of the present invention, equipment such as a forging heating furnace, a press, a ring rolling mill, a manipulator, and a bulging machine needs to be provided. The following takes an aluminum alloy of grade 2A70 as an example to detail the specific implementation of this method:

[0022] The main chemical element contents (by weight percentage) of this alloy are: Mn content ≤ 0.20%, Si content ≤ 0.35%, Ni content 0.90% - 1.50%, Ti content 0.02% - 0.10%, Cu content 1.9% - 2.5%, Fe content 0.90% - 1.50%, Mg content 1.4% - 1.8%, Zn content ≤ 0.30%, and the balance is Al. The raw materials pass the re-inspection.

[0023] The specific steps of this method are as follows:

[0024] Cut the aluminum alloy into bars according to the specification of Ф400×572mm. After heating the heating furnace to 450 ± 10°C, put the aluminum alloy bars into the heating furnace and keep them warm for 12 hours; then transfer the heat-insulated aluminum alloy bars to the press, and the transfer time is less than 50 seconds; on the press, upset the billet to H = 280mm, and the deformation process takes about 13s, and the downward pressure speed of the upper pressure block is 30mm / s - 40mm / s. Use a punch to punch a blind hole, the specification of the punch is Ф185mm, the press presses the whole punch into the billet, and after punching the blind hole, turn the forging over so that the blind hole with the punch faces down and place it on the drain pan to punch a through hole until an aluminum alloy ring blank is obtained;

[0025] Adopt multi-pass rolling. For the first pass, heat the punched aluminum alloy ring blank in the furnace while it is still hot, keep it at 450±10°C for 6 hours, and then roll it on a ring rolling mill. The dimensional requirements are Ф670±10×Ф370±10×Hmm, and level the height to H = 270±5mm; for the second pass, heat the aluminum alloy ring blank in the furnace while it is still hot, keep it at 450±10°C for 6 hours, and then roll it on a ring rolling mill. The dimensional requirements are Ф904±10×Ф704±10×Hmm, and level the height to H = 265±5mm; for the third pass, heat the aluminum alloy ring blank in the furnace while it is still hot, keep it at 450±10°C for 6 hours, and then roll it on a ring rolling mill. The dimensional requirements are Ф1218±10×Ф1078±10×Hmm, and level the height to H = 260±5mm; for the fourth pass, heat the aluminum alloy ring blank in the furnace while it is still hot, keep it at 450±10°C for 6 hours, and then perform the final rolling on a ring rolling mill. The dimensional requirements are Ф1490±5×Ф1378±5×247±5mm, and level the height to H = 260±5mm; thus obtaining the aluminum alloy ring rolled piece.

[0026] After heating the heating furnace to 530±5°C, load the aluminum alloy ring rolled piece after final rolling into the heating furnace and keep it for 3 hours, then cool it in hot water at a temperature higher than 85°C for 15 minutes, and then transfer it to a cold water tank to cool it to room temperature.

[0027] As shown in the Figure 1 attachment, put 4 sets of the solution-treated aluminum alloy ring rolled pieces on the periphery of the bulging block 3 of the bulging machine. At room temperature, start the bulging machine to apply a downward force F on the mandrel 1 to make it move downward, thereby driving the radial slider 2 and the bulging block 3 to perform radial movement. At the same time, apply an axial pressure F2 to the lower pressing ring 5 to ensure that the axial dimension of the aluminum alloy ring rolled piece 4 does not change; the bulging deformation amount of the aluminum alloy ring rolled piece 4 is controlled within 2%. After cold bulging, the dimensions of the aluminum alloy ring rolled piece 4 are Ф1518±2×Ф1408±2×247±6mm, thus obtaining the aluminum alloy ring piece.

[0028] Perform aging treatment on the bulged aluminum alloy ring piece. The aging treatment should be carried out within 4 hours after the solution process; load the aluminum alloy ring piece into the heating furnace, heat it up to 170 - 200°C with the furnace, keep it for 13 hours; take out the aluminum alloy ring piece and cool it by air cooling in a dispersed manner.

Claims

1. A method for bulging a large aluminum alloy ring forging, characterized in that, It includes the following steps: Cut the aluminum alloy bar stock according to certain specifications. After heating the heating furnace to 450 ± 10 °C, put the aluminum alloy bar stock into the heating furnace and keep it warm for 12 hours; then transfer the heat-insulated aluminum alloy bar stock to the press, and the transfer time is less than 50 seconds; upset the blank to H on the press, the deformation process takes about 13 s, and the downward pressing speed of the upper pressing block is 30 mm / s to 40 mm / s; use a punch to punch a blind hole, the press presses the whole punch into the blank, after punching the blind hole, turn over the forging so that the blind hole with the punch faces down and place it on the drain pan to punch a through hole, and wait until the aluminum alloy ring blank is obtained; Adopt multi-pass rolling. For the first pass, heat the aluminum alloy ring blank with punched holes back to the furnace while it is hot, keep it warm at 450 ± 10 °C for 6 hours, and roll it on the ring rolling mill. The dimensional requirements are Ф670 ± 10 × Ф370 ± 10 × Hmm, and level the height to H = 270 ± 5 mm; for the second pass, heat the aluminum alloy ring blank back to the furnace while it is hot, keep it warm at 450 ± 10 °C for 6 hours, and roll it on the ring rolling mill. The dimensional requirements are Ф904 ± 10 × Ф704 ± 10 × Hmm, and level the height to H = 265 ± 5 mm; for the third pass, heat the aluminum alloy ring blank back to the furnace while it is hot, keep it warm at 450 ± 10 °C for 6 hours, and roll it on the ring rolling mill. The dimensional requirements are Ф1218 ± 10 × Ф1078 ± 10 × Hmm, and level the height to H = 260 ± 5 mm; for the fourth pass, heat the aluminum alloy ring blank back to the furnace while it is hot, keep it warm at 450 ± 10 °C for 6 hours, and perform the final rolling on the ring rolling mill. The dimensional requirements are Ф1490 ± 5 × Ф1378 ± 5 × 247 ± 5 mm, and level the height to H = 260 ± 5 mm; obtain the aluminum alloy ring rolled piece; After heating the heating furnace to 530 ± 5 °C, put the aluminum alloy ring rolled piece after final rolling into the heating furnace and keep it warm for 3 hours, then cool it in hot water at a temperature higher than 85 °C for 15 minutes, and then transfer it to a cold water tank and cool it to room temperature; Put the aluminum alloy ring rolled piece after solution treatment on the periphery of the bulging block of the bulging machine. At room temperature, start the bulging machine to apply a downward force F on the mandrel to make it move downward, thereby driving the radial slider and the bulging block to perform radial movement. At the same time, apply an axial pressure F2 to the downward pressing ring to ensure that the axial dimension of the ring forging does not change; the bulging deformation amount of the aluminum alloy ring rolled piece is controlled within 2%, and the size of the ring forging after cold bulging is Ф1518 ± 2 × Ф1408 ± 2 × 247 ± 6 mm, and obtain the aluminum alloy ring; Perform aging treatment on the bulged aluminum alloy ring. Put the aluminum alloy ring into the heating furnace, heat it up to 170 - 200 °C with the furnace, and keep it warm for 13 hours; take out the aluminum alloy ring and cool it by air cooling in a dispersed manner.

2. The hydroforming method of the large aluminum alloy ring forging according to claim 1, characterized in that, The specification of the aluminum alloy bar stock is Ф400 × 572 mm.

3. The hydroforming method of the large aluminum alloy ring forging according to claim 1, characterized in that During the upsetting process, upset the blank to H = 280 mm.

4. The hydroforming method of the large aluminum alloy ring forging according to claim 1, characterized in that, The specification of the punch is Ф185 mm.

5. The method for bulging a large aluminum alloy ring forging according to claim 1, characterized in that, The aging treatment is carried out within 4 hours after the solution treatment.

6. The hydroforming method of the large aluminum alloy ring forging according to any one of claims 1 to 5, characterized in that, The aluminum alloy is 2A70 alloy.

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