An isothermal rolling method for aluminum alloy rings

Abstract

This invention provides an isothermal rolling method for aluminum alloy rings, comprising: heating the aluminum alloy ring billet to a target initial rolling temperature for ring rolling, wherein the ring rolling includes: an adaptation stage, a speed-up stage, a stabilization stage, a deceleration stage, and a rounding stage; the adaptation stage and the speed-up stage control the amount of coolant to reduce the temperature rise trend; the stabilization stage controls the feed speed and main roll speed to reduce the temperature drop trend; the deceleration stage and the rounding stage heat the main roll and tapered roll to ensure that the final rolling temperature of the ring is within the target temperature range. This invention employs isothermal rolling, regulating the feed speed and main roll speed, and supplementing with heating and cooling systems to achieve a more uniform and stable temperature distribution in the aluminum alloy ring, controlling the ring forming temperature within a very narrow range to refine grains, reducing rolling defects such as folding, peeling, and cracking, and achieving a uniform microstructure in each quadrant of the aluminum alloy ring, effectively controlling its overall microstructure and properties.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy ring technology, and particularly relates to an isothermal rolling method for aluminum alloy rings. Background Technology

[0002] Aluminum alloy rings are a critical type of connector and structural component, used in connectors, transition rings, and adapter frames of spacecraft such as launch vehicles and space stations. As the commercial aerospace sector enters a stage of rapid development, the market gap for them is enormous, and higher performance requirements are being placed on them.

[0003] Existing aluminum alloy ring rolling technology generally involves hot rolling, which involves heating and holding the aluminum alloy ring billet at high temperatures for a long time, resulting in significant energy loss. During the hot rolling process, the temperature on the ring is unevenly distributed, with the highest temperature in the central area and gradually decreasing towards the outer diameter. The lowest temperature is at the outer diameter of the ring. In the early stages of hot rolling, there is a significant temperature rise, leading to grain growth. As the diameter increases and the wall thickness decreases, the temperature drops in the later stages of hot rolling, resulting in uneven grain size and properties, which can easily lead to rolling defects such as folding, peeling, and cracking.

[0004] During the rolling process, the surface of the ring exchanges heat with various media such as the main roll, cone roll, core roll, clamping roll, and air, resulting in rapid cooling. However, the core exchanges heat with the surface area with a smaller temperature difference, resulting in less significant cooling. As rolling progresses, the core is prone to temperature rise. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an isothermal rolling method for aluminum alloy rings. The method provided by the present invention provides aluminum alloy rings with uniform microstructure in each quadrant, which can effectively control the overall microstructure and properties.

[0006] This invention provides an isothermal rolling method for aluminum alloy rings, comprising:

[0007] The aluminum alloy ring billet is heated to the target initial rolling temperature and then ring rolled, the ring rolling comprising:

[0008] The stages are: adaptation, acceleration, stabilization, deceleration, and completion.

[0009] The adaptation and acceleration phases control the amount of coolant to reduce the tendency for temperature rise.

[0010] The stabilization phase controls the feed speed and main roll speed to reduce the tendency of temperature drop;

[0011] The deceleration and rounding stages heat the main roll and tapered roll to ensure that the final rolling temperature of the ring rolling is within the target temperature range.

[0012] Preferably, the aluminum alloy ring blank is composed of 2A14 aluminum alloy.

[0013] Preferably, the aluminum alloy ring blank is an aluminum alloy ring blank that has undergone multi-directional forging.

[0014] Preferably, the holding time during the heating process is controlled at 1.5 to 3 min / mm based on the minimum thickness of the aluminum alloy ring blank;

[0015] The heating process also includes:

[0016] Heat the main roll and tapered roll to the target rolling temperature;

[0017] The target initial rolling temperature is the upper limit of the ring rolling temperature range.

[0018] Preferably, the temperature difference during the ring rolling process is 10–30°C.

[0019] Preferably, the diameter growth rate during the ring rolling process is 1–5 mm / s;

[0020] The outer diameter of the adaptation stage is 50-180 mm larger than the outer diameter of the aluminum alloy ring blank.

[0021] The change in outer diameter during the acceleration phase accounts for 25-40% of the total change in outer diameter during the acceleration and stabilization phases.

[0022] The change in outer diameter during the steady-state phase accounts for 60-75% of the total change in outer diameter during the acceleration and steady-state phases.

[0023] The outer diameter change during the deceleration and circularization stages is 50–180 mm.

[0024] Preferably, the spray rate of the coolant is 10-40 L / min.

[0025] Preferably, the feed rate is 0.3 to 1.5 mm / s.

[0026] Preferably, the main roller rotation speed is 300-1250 r / min.

[0027] Preferably, the main roll and the cone roll are heated within 1 to 3 minutes to ensure that the final rolling temperature of the ring rolling is within the target temperature range.

[0028] This invention employs isothermal rolling, adjusting the feed speed and main roll speed, and supplementing with heating and cooling systems to make the temperature distribution of the aluminum alloy ring more uniform and stable. By controlling the ring forming temperature within a very narrow range, grain refinement is achieved, reducing rolling defects such as folding, peeling, and cracking. This results in a uniform microstructure in each quadrant of the aluminum alloy ring, effectively controlling its overall microstructure and properties. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides an isothermal rolling method for aluminum alloy rings, comprising:

[0031] The aluminum alloy ring billet is heated to the target initial rolling temperature and then ring rolled, the ring rolling comprising:

[0032] The stages are: adaptation, acceleration, stabilization, deceleration, and completion.

[0033] The adaptation and acceleration phases control the amount of coolant to reduce the tendency for temperature rise.

[0034] The stabilization phase controls the feed speed and main roll speed to reduce the tendency of temperature drop;

[0035] The deceleration and rounding stages heat the main roll and tapered roll to ensure that the final rolling temperature of the ring rolling is within the target temperature range.

[0036] In this invention, the aluminum alloy ring blank is preferably composed of 2A14 aluminum alloy.

[0037] In this invention, the aluminum alloy ring blank is preferably an aluminum alloy ring blank with a suitable inner hole size obtained through multi-directional forging. In this invention, the method for preparing the aluminum alloy ring blank preferably includes:

[0038] The aluminum alloy billet is forged by five upsetting and four drawing processes. The forged billet is then punched and expanded to obtain an aluminum alloy ring billet.

[0039] In this invention, the first upsetting and drawing in the five-upsetting and four-drawing process is pre-forging; the single deformation amount in the upsetting process is preferably 45-70%, more preferably 50-65%; the upsetting speed is preferably <10mm / s, more preferably 5-8mm / s; the single deformation amount in the drawing process is preferably 20-50%, more preferably 30-40%, and most preferably 35%; the drawing pressing speed is preferably <25mm / s, more preferably 15-20mm / s.

[0040] In this invention, the outer diameter of the aluminum alloy ring blank is preferably 1250-1350 mm, more preferably 1280-1320 mm, and most preferably 1300 mm; the wall thickness is preferably 250-350 mm, more preferably 280-320 mm, and most preferably 300 mm; the height is preferably 200-300 mm, more preferably 220-280 mm, and most preferably 240-260 mm.

[0041] In this invention, the holding time during the heating process is preferably controlled at 1.5 to 3 min / mm based on the minimum thickness of the aluminum alloy ring blank, and most preferably at 2 min / mm.

[0042] In this invention, the heating process preferably further includes:

[0043] Heat the main roll and tapered roll to the target rolling temperature.

[0044] In this invention, the target initial rolling temperature is preferably the upper limit of the ring rolling temperature range. Specifically, the target initial rolling temperature is preferably 190–210°C, more preferably 195–205°C, and most preferably 200°C; the holding time during the heating process is preferably 450–550 min, more preferably 480–520 min, and most preferably 500 min.

[0045] In this invention, the ring rolling is preferably carried out in a ring rolling mill, where ring rolling process parameters are input and the material is fed for ring rolling.

[0046] In this invention, the temperature difference during the ring rolling process is preferably 10–30°C, more preferably 15–25°C, and most preferably 20°C. In this invention, the ring rolling temperature is preferably 190–210°C, more preferably 195–205°C, and most preferably 200°C.

[0047] In this invention, the preferred ring rolling process parameters include: diameter growth rate, outer diameter, wall thickness, and height; the preferred diameter growth rate is 1–5 mm / s, more preferably 2–4 mm / s, and most preferably 3 mm / s. In this invention, the preferred diameter growth rate during the adaptation stage is 3–5 mm / s, more preferably 4 mm / s. In this invention, the preferred diameter growth rate during the acceleration stage is 3.5–5 mm / s, more preferably 5.0 mm / s. In this invention, the preferred diameter growth rate during the stabilization stage is 3.5–5 mm / s, more preferably 5.0 mm / s. In this invention, the preferred diameter growth rate during the deceleration stage is 0.5–1.5 mm / s, more preferably 1.0 mm / s. In this invention, the preferred diameter growth rate during the rounding stage is 0.5–1.5 mm / s, more preferably 1.0 mm / s.

[0048] In this invention, the outer diameter of the adaptation stage is preferably 50-180 mm larger than the outer diameter of the aluminum alloy ring blank, more preferably 80-150 mm, and most preferably 100-120 mm; the outer diameter change during the acceleration stage preferably accounts for 25-40% of the total outer diameter change during the acceleration and stabilization stages, more preferably 30-35%; the outer diameter change during the stabilization stage preferably accounts for 60-75% of the total outer diameter change during the acceleration and stabilization stages, more preferably 65-70%; the outer diameter change during the deceleration stage and the rounding stage is preferably 50-180 mm, more preferably 80-160 mm, more preferably 100-140 mm, and most preferably 120 mm.

[0049] In this invention, the cooling system's coolant spray volume is preferably adjusted to reduce the temperature rise trend based on the real-time temperature detection system's response. The coolant spray volume is preferably 10-40 L / min, more preferably 20-30 L / min, and most preferably 25 L / min. The temperature control during the adaptation and acceleration phases is preferably 170-220°C, more preferably 180-210°C, and most preferably 190-200°C.

[0050] In this invention, the tendency to reduce temperature drop is minimized, and the temperature at which the ring undergoes uniform deformation is maintained. In this invention, the feed speed is preferably 0.3–1.5 mm / s, more preferably 0.5–1.2 mm / s, and most preferably 0.8–1.0 mm / s; the main roller speed is preferably 300–1250 r / min, more preferably 500–1200 r / min, and most preferably 800–1000 r / min; the temperature control range during the stabilization phase is preferably 170–220°C, more preferably 180–210°C, and most preferably 190–200°C.

[0051] In this invention, the heating of the main roll and the tapered roll is preferably performed online; preferably, the rolling temperature range is reached in a short time; preferably, the ring rolling temperature is brought to 170-220°C within 1-3 minutes, more preferably within 1.5-2.5 minutes, and most preferably within 2 minutes.

[0052] Currently, most aluminum alloy rings are produced by hot rolling, which is prone to temperature rise and fall during the rolling process. This can lead to uneven performance and grain size distribution, and may result in defects such as folding, peeling, and cracking. This invention uses isothermal rolling to refine the grains, reduce cracking defects, and enable the aluminum alloy rings to have a uniform microstructure and excellent performance in each quadrant.

[0053] Example 1

[0054] The 2A14 aluminum alloy ring blank, which has undergone multi-directional forging, has dimensions of approximately Φ1285×Φ719×242mm. The specific preparation method is as follows: the forging blank is prepared by five upsetting and four drawing operations, and the deformation is controlled. The first upsetting and drawing are pre-forging operations, in which the deformation of the single upsetting operation is 65% and the deformation of the single drawing operation is 35%. The upsetting speed is 7.8mm / s and the drawing speed is 12~18mm / s.

[0055] The aluminum alloy ring billet is heated to the target initial rolling temperature of 200±5℃ and held for 500 minutes. The main roll and tapered roll are also heated to 200±5℃. The rolling temperature range of the ring is 190~210℃.

[0056] Start the ring rolling mill, input the ring rolling process parameters, set the rolling process as shown in the table below, and then load the material for ring rolling:

[0057] Diameter growth rate (mm / s) outer diameter (mm) Wall thickness (mm) Height (mm) Ring blank size / 1285 283 242 Adaptation phase 4 1335 265 242 Acceleration Phase 5 1685 208 223 Stable phase 5 2385 148 207 deceleration phase 1 2520 144 200 Complete circle stage 1 2584 140 200

[0058] During the initial rolling stage, namely the adaptation and acceleration stages, the cooling liquid spray rate of the cooling system is adjusted to 20-30 L / min based on the real-time temperature monitoring system response, in order to reduce the temperature rise trend, with a temperature range of 190-210℃.

[0059] During the stabilization stage of rolling, the feed speed is controlled at 0.4 mm / s and the main roll speed is controlled at 780 r / min to reduce the temperature drop and maintain the temperature of uniform deformation of the ring in the range of 190 to 210℃.

[0060] During the later stages of rolling, namely the deceleration and rounding stages, the main roll and tapered roll are heated within 2 minutes to ensure that the rolling temperature of the ring is within 190-210℃.

[0061] Comparative Example 1

[0062] Using the forged ring billet from Example 1, the aluminum alloy ring billet was heated to the target initial rolling temperature of 450±5℃ using a conventional hot rolling process, held for 700 min, with a diameter growth rate of 2-3 mm / min, and hot rolled to the target size of Φ2584×Φ2304×200 mm, with a final rolling temperature of 405℃.

[0063] Performance testing

[0064] The rings prepared in Example 1 and Comparative Example 1 of this invention were subjected to heat treatment. The heat treatment method was as follows: solution treatment was performed first, followed by aging treatment; the solution treatment temperature was 501±3℃, and the holding time was 8 hours; the aging temperature was 165±3℃, and the holding time was 9 hours; then the mechanical properties were tested according to GB / T228, and the test results are as follows:

[0065]

[0066] In this invention, isothermal rolling can make the temperature distribution of the ring more uniform and stable by adjusting the feed speed and main roll speed and supplementing with heating and cooling systems. The forming temperature of the aluminum alloy ring can be controlled within a very narrow range, which can effectively regulate its overall microstructure and properties.

[0067] While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not intended to limit the invention. It will be readily understood by those skilled in the art that various changes may be made to suit particular circumstances, materials, compositions, substances, methods, or processes to the objectives, spirit, and scope of this application without departing from the true spirit and scope of the invention as defined by the appended claims. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a particular order, it should be understood that these operations may be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of the invention. Therefore, unless specifically indicated herein, the order and grouping of operations are not a limitation of this application.

Claims

1. A method for isothermal rolling of an aluminum alloy ring, comprising: heating an aluminum alloy ring blank to a target rough rolling temperature for ring rolling, the target rough rolling temperature being 190-210℃, the ring rolling comprising: an adaptation stage, a speed-up stage, a stable stage, a speed-down stage, and a rounding stage; the adaptation stage and the speed-up stage controlling the amount of cooling liquid to reduce the tendency of temperature rise; the stable stage controlling the feed speed and the main roller speed to reduce the tendency of temperature drop; the feed speed being 0.3-1.5 mm / s, and the main roller speed being 300-1250 r / min; the speed-down stage and the rounding stage heating the main roller and the taper roller to make the final rolling temperature of the ring rolling within a target temperature range; a temperature difference in the ring rolling process being 10-30℃; an outer diameter size of the adaptation stage being 50-180 mm larger than that of the aluminum alloy ring blank; an outer diameter change amount of the speed-up stage accounting for 25-40% of a total outer diameter change amount of the speed-up stage and the stable stage; an outer diameter change amount of the stable stage accounting for 60-75% of the total outer diameter change amount of the speed-up stage and the stable stage; outer diameter change amounts of the speed-down stage and the rounding stage being 50-180 mm, respectively.

2. The method of claim 1, wherein, the aluminum alloy ring blank being a 2A14 aluminum alloy.

3. The method of claim 1, wherein, the aluminum alloy ring blank being an aluminum alloy ring blank after multi-directional forging breakdown.

4. The method of claim 1, wherein, a diameter growth speed in the ring rolling process being 1-5 mm / s.

5. The method of claim 1, wherein, a spraying amount of the cooling liquid being 10-40 L / min.

6. The method of claim 1, wherein, the main roller and the taper roller being heated within 1-3 min to make the final rolling temperature of the ring rolling within the target temperature range.

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