A method for rolling tall cylindrical forgings

Abstract

This invention discloses a method for rolling high-cylindrical forgings, with the following specific steps: S1: Pre-treat the billet to ensure the rolling angle meets the rolling requirements; S2: Heat the pre-treated billet to 1150℃~1200℃ and hold for 1.5~2 hours before rolling into a ring; S3: Pre-set the initial ring speed increase of the ring rolling mill to V0, at which point the outer diameter of the billet is R0; S4: In the first ring rolling stage, control the ring speed increase to V0 until the outer diameter of the billet reaches R1; S5: In the second ring rolling stage, control the ring speed increase to V1 and continue rolling until the outer diameter of the billet reaches R2; S6: In the third ring rolling stage, control the ring speed increase to V2 until the outer diameter of the billet reaches R3; S7: In the fourth ring rolling stage, control the ring speed increase to V3 and roll the ring to the final size. This invention designs the billet ring rolling process and, by controlling the rolling curve, not only improves the quality of the rolled ring but also reduces the forging allowance and lowers production costs.

Description

Technical Field

[0001] This invention belongs to the field of forging technology, and in particular to a method for rolling high cylindrical forgings. Background Technology

[0002] With the rapid development of my country's aerospace industry, modern defense industry, and transportation industry, the demand for high-profile cylindrical forgings is increasing as one of the main components of spacecraft. High-profile cylindrical forgings refer to forgings with a height / outer diameter ratio ≥ 2.

[0003] Traditional spacecraft's tall cylindrical shell sections widely employ two machining processes: 1) direct ring rolling by increasing the blank machining allowance; 2) welding multiple forging sections. However, both methods involve relatively large blank machining allowances, leading to low material utilization and high production costs. Furthermore, they place high demands on the forming process. If the rolling angle is large during ring rolling, the forging will have uneven ends, with excess material accumulating at one end. If the rolling angle is small, pits will appear on the forging surface, resulting in poor finished product stability and reliability. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention discloses a method for rolling high cylindrical forgings. By designing the billet ring rolling process and controlling the rolling curve, not only is the quality of the rolled ring improved, but the forging allowance is also reduced, thereby lowering production costs.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A method for rolling tall cylindrical forgings, the specific steps of which are as follows:

[0007] S1: Pre-treat the billet to ensure that the rolling angle of the billet meets the rolling requirements;

[0008] S2: Heat the pretreated billet to 1150℃~1200℃ and hold it for 1.5~2 hours before taking it out of the furnace for ring rolling;

[0009] S3: Pre-set the initial ring speed of the ring rolling mill to V0. At this time, the outer diameter of the billet is R0.

[0010] S4: During the first ring rolling stage, the ring speed is controlled to be V0 for ring rolling until the outer diameter of the billet reaches R1;

[0011] S5: During the second ring rolling stage, the control ring speed increases to V1 to continue ring rolling until the outer diameter of the billet reaches R2;

[0012] S6: During the third ring rolling stage, the ring speed is controlled to increase to V2 for ring rolling until the outer diameter of the billet reaches R3;

[0013] S7: During the fourth ring rolling stage, the control ring speed is reduced to V3, and the ring is rolled to the final size.

[0014] Preferably, the rolling angle θ satisfies the following condition:

[0015]

[0016] In the formula, H1 is the height of the billet before rolling the ring; H2 is the height of the billet after rolling the ring; D1 is the wall thickness of the billet before rolling the ring; D2 is the wall thickness of the billet after rolling the ring; and the value of θ ranges from 0.4 to 0.5.

[0017] Preferably, the cycle growth rates V0, V1, V2, and V3 satisfy the following conditions:

[0018] V1≥V2≥V0≥V3;

[0019] Preferably, the deformation of R1 satisfies the following equation:

[0020]

[0021] Where C1 is the deformation rate, and its value ranges from 5% to 10%.

[0022] Preferably, the deformation of R2 satisfies the following equation:

[0023]

[0024] Where C2 is the deformation rate, and its value ranges from 5% to 10%.

[0025] Preferably, the deformation of R3 satisfies the following equation:

[0026]

[0027] Wherein, C3 is the deformation rate, and its value ranges from 5% to 10%.

[0028] Beneficial effects: This invention discloses a method for irregularly shaped rolling of large high-temperature alloy casings for aerospace applications, which has the following advantages:

[0029] (1) The present invention reduces the rolling allowance of forgings and lowers production costs by designing the rolling ring process;

[0030] (2) By controlling the rolling curve and adopting segmented rolling, the present invention not only reduces the end face pits in the early stage of ring rolling, but also rounds the ring in the later stage of ring rolling, eliminating the elliptical and large-small head phenomenon, thereby improving the rolling quality. Attached Figure Description

[0031] Figure 1 The rolling curve of Example 1;

[0032] Figure 2 This is a schematic diagram of the finished product of Example 1;

[0033] Figure 3 The rolling curve is for Comparative Example 1;

[0034] Figure 4 This is a schematic diagram of the finished product of Comparative Example 1;

[0035] Figure 5 The rolling curve is for Comparative Example 2;

[0036] Figure 6 This is a schematic diagram of the finished product of Comparative Example 2. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] Example 1

[0039] like Figure 2 The high-cylindrical forging shown has the following dimensions: Φ665×Φ500×1300 (mm). The raw material (stainless steel 1Cr12Ni2WMoVNbN) has the following specifications: Weighing 1600kg, its specific rolling steps are as follows:

[0040] S1: Pre-treat the billet to ensure the rolling angle meets rolling requirements. The specific pre-treatment method is as follows:

[0041] S1-1: Round and upset the raw material to Φ660×600;

[0042] S1-2: The uplifted billet is then punched to: Φ670×Φ200×600;

[0043] S1-3: Lengthen the blank mandrel to: Φ480*Φ200*1315;

[0044] S1-4: Expand the hole of the elongated billet frame to: Φ520*Φ280*1315; at this time, the rolling angle θ is satisfied to be 0.4.

[0045] S2: Heat the pretreated billet to 1200℃ and hold for 1 hour, then remove it from the furnace according to... Figure 1 The rolling curve shown is used for ring rolling;

[0046] S3: The initial ring speed increase of the ring rolling mill is set to V0 as 2mm / s in advance. At this time, the outer diameter of the billet R0 is 520mm.

[0047] S4: During the first ring rolling stage, the ring speed increase is controlled at V0, which is 2 mm / s, until the billet outer diameter reaches R1 = 550 mm. At this point, the requirements are met.

[0048] S5: During the second ring rolling stage, the control ring speed increase V1 is raised to 4 mm / s to continue ring rolling until the billet outer diameter reaches R2 = 580 mm, at which point the second ring rolling stage begins. At this point, the following conditions are met:

[0049] S6: During the third ring rolling stage, the control ring speed increase V2 is set to 3 mm / s for ring rolling until the billet outer diameter reaches R3 = 630 mm. At this point, the requirements are met.

[0050] S7: During the fourth ring rolling stage, the control ring speed is reduced to V3 at 1mm / s, and the ring is rolled to the final size Φ665*Φ500*1300.

[0051] In the above rolling process, the first rolling stage is the biting stage, where the ring speed increase is relatively slow. The main purpose is to eliminate uneven wall thickness of the billet and ensure smooth rolling of the billet. The second stage is the main ring growth stage, where the ring speed increase is the fastest. The main purpose is to ensure the ring grows while reducing end face pits. The third stage is the secondary ring growth stage, where the ring speed increase slows down. The main purpose is to ensure the ring grows while reducing the speed difference between the ring growth stage and the rounding stage, and to ensure the ellipticity of the ring. The fourth stage is the ring shaping stage, where the ring speed increase slows down further. The main purpose is to ensure the ellipticity of the ring and address the issue of uneven ends.

[0052] Comparative Example 1

[0053] The raw materials are the same as in Example 1, and the pretreatment method for the billet in Comparative Example 1 is the same as in Example 1, based on the following... Figure 3 The rolling curve shown is used for ring rolling, and the final product is as follows: Figure 4 As shown, during rolling, the forging ring speed increases slowly at first and then rapidly, resulting in a large reduction at the end face. Consequently, the pressure from the upper part cannot be fully transferred to the lower part, leading to uneven forgings and elliptical shapes. Because of this unevenness, the rolling method used in Comparative Example 1 requires a larger allowance for the larger end to ensure sufficient allowance for the smaller end.

[0054] Comparative Example 2

[0055] The raw materials are the same as in Example 1, and the pretreatment method for the billet in Comparative Example 1 is the same as in Example 1, based on the following... Figure 5 The rolling curve shown is used for ring rolling, and the final product is as follows: Figure 6As shown, during rolling, the forging ring speed increases rapidly at first and then slows down. The amount of material reduced at the forging end face is relatively small, and the material in the inner hole and outer diameter is squeezed towards the center, resulting in less flow in the center of the wall thickness. This leads to pitting problems on the forging end face. Due to the tendency for end face grooves to form, the rolling method in Comparative Example 2 requires a larger height allowance to ensure the finished product dimensions.

[0056] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for rolling tall cylindrical forgings, characterized in that, The specific steps are as follows: S1: Pre-treat the billet to ensure that the rolling angle of the billet meets the rolling requirements; S2: Heat the pretreated billet to 1150℃~1200℃ and hold it for 1.5~2 hours before taking it out of the furnace for ring rolling; S3: Preset the initial ring speed of the ring rolling mill to V0. At this time, the outer diameter of the billet is R0. S4: During the first ring rolling stage, the ring speed is controlled to be V0 for ring rolling until the outer diameter of the billet reaches R1; S5: During the second ring rolling stage, the control ring speed increases to V1 to continue ring rolling until the outer diameter of the billet reaches R2; S6: During the third ring rolling stage, the ring speed is controlled to increase to V2 for ring rolling until the outer diameter of the billet reaches R3; S7: During the fourth ring rolling stage, the control ring speed is reduced to V3, and the ring is rolled to the final size; The rolling angle θ satisfies the following condition: In the formula, H1 is the height of the billet before rolling; H2 is the height of the billet after rolling; D1 is the wall thickness of the billet before rolling; D2 is the wall thickness of the billet after rolling; and θ ranges from 0.4 to 0.

5. The cycle growth rates V0, V1, V2, and V3 satisfy the following conditions: V1≥V2≥V0≥V3.

2. The method for rolling tall cylindrical forgings according to claim 1, characterized in that, The deformation of R1 satisfies the following equation: Where C1 is the deformation rate, and its value ranges from 5% to 10%.

3. The method for rolling tall cylindrical forgings according to claim 1, characterized in that, The deformation of R2 satisfies the following equation: Where C2 is the deformation rate, and its value ranges from 5% to 10%.

4. The method for rolling tall cylindrical forgings according to claim 1, characterized in that, The deformation of R3 satisfies the following equation: Wherein, C3 is the deformation rate, and its value ranges from 5% to 10%.

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