Method for controlling wall thickness uniformity of large-length-diameter-ratio thin-wall seamless aluminum alloy lining

Abstract

The invention discloses a large-length-diameter-ratio thin-wall seamless aluminum alloy lining wall thickness uniformity control method which comprises the steps that firstly, an aluminum alloy pipe is clamped on a double-spinning-roller numerical control spinning machine, a pipe blank for closing is prepared through multiple passes in a staggered spinning mode, then the pipe blank is clamped on a clamp of closing spinning equipment after being subjected to annealing treatment, and the aluminum alloy pipe is subjected to high-speed spinning. And the pipe blank extends out of the end face of the clamp, combined track closing-in spinning is adopted till the pipe blank is spun to be in a preset shape, and a lining blank is formed. And the lining blank is subjected to heat treatment, finally, the lining blank subjected to heat treatment is machined, and the formed aluminum alloy lining is obtained. According to the method, a multi-pass rolling spinning method is adopted for preparing the closing-in pipe blank, a combined track is adopted for closing-in spinning, the wall thickness is reduced through the technology combining turning and milling and mainly adopting milling, and high-precision preparation of the large-length-diameter-ratio thin-wall seamless aluminum alloy lining is achieved.

Description

Technical Field

[0001] The invention relates to a method for controlling the uniformity of the wall thickness of a thin-wall seamless aluminum alloy liner with a large aspect ratio, and belongs to the technical field of manufacturing the liner of a seamless gas cylinder for aerospace use. Background Art

[0002] The lining of seamless gas cylinders for aerospace use requires light weight and high precision. Before the end-spinning, the wall thickness of the tube blank must be uniform and high precision must be maintained. After the end-spinning, the inner surface must be free of defects such as wrinkles and cracks. After the outer surface is machined, there are high requirements for wall thickness deviation and uniformity, straightness, and roundness (wall thickness ≤2.0mm, wall thickness tolerance ≤0.20mm, straightness ≤1.0mm, roundness ≤0.50mm), which greatly increases the process requirements for each process. At present, foreign countries have mastered the manufacturing technology of thin-walled high-precision seamless aluminum alloy linings. The thickness of the seamless aluminum lining produced by the American Structural Composites Industries in 2011 can reach 0.8mm. At present, the following method is used to prepare thin-walled seamless linings in China, that is, multiple sets of molds are used to deep-draw and form the lining tube blanks, and the outer surface of the lining is manually polished after the closing and spinning. The manufacturing process has many flow steps and takes a long time. At the same time, the lining is manually polished to thin the wall thickness, which is very easy to cause uneven wall thickness distribution and large deviation, and deviation from the design requirements. The user is either forced to make concessions or directly scrap the components that deviate from the requirements. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, and propose a method for controlling the uniformity of the wall thickness of a thin-walled seamless aluminum alloy lining with a large aspect ratio, adopt a multi-pass rolling and thinning spinning method to prepare a closed tube blank, adopt a combined trajectory for closing spinning, and adopt a process combining turning and milling with milling as the main method to thin the wall thickness, so as to achieve high-precision preparation of a thin-walled seamless aluminum alloy lining with a large aspect ratio, without defects such as wrinkles and cracks on the inner surface of the lining, and the wall thickness deviation (the difference between the measured maximum wall thickness and the minimum wall thickness) is ≤0.20mm.

[0004] The technical solution of the present invention is:

[0005] A method for controlling the uniformity of the wall thickness of a thin-walled seamless aluminum alloy lining with a large aspect ratio, comprising:

[0006] Step 1: Mount the aluminum alloy tube on a double-wheel CNC spinning machine, adopt a staggered spinning method, and go through multiple passes to prepare a tube blank for closing;

[0007] Step 2: annealing the tube blank after thinning and spinning;

[0008] Step 3: Clamp the annealed tube blank onto the fixture of the closing spinning equipment, extend the tube blank out of the fixture end face, and use a combined trajectory to close the tube blank until the tube blank is spun into a preset shape to form a liner blank;

[0009] Step 4: heat treating the lining blank;

[0010] Step 5: Mechanically process the heat-treated liner blank to obtain a formed aluminum alloy liner.

[0011] Furthermore, in step 1, staggered spinning is used to prepare the closed tube blank, and a support device is placed at 80mm-100mm away from the starting position of spinning to support the spinning die, and the wall thickness deviation of the prepared closed tube blank is ≤0.30mm. The support device includes a base and a support roller, and the support roller contacts the circumferential end surface of the spinning die and moves with the rotation of the spinning die, thereby supporting the spinning die and avoiding the "lower head effect" of the spinning die.

[0012] Further, in step 1, 4 passes are used to prepare the tube blank for closing, and all 4 passes are cold spinning and positive spinning; the front roller is defined as No. 1, and the lagging roller is defined as No. 2, that is, roller No. 1 is 6mm-10mm ahead of roller No. 2; the inner diameter of the tube blank for closing is 350mm-450mm, the length is 1.3m-1.5m, and the wall thickness is 6mm-8mm. The specific forming process is as follows:

[0013] In the first pass, the gap between the No. 1 roller and the die is 16.10mm-16.20mm, the gap between the No. 2 roller and the die is 14.50mm-14.60mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 70mm / min-80mm / min;

[0014] For the second pass, the clearance between the No. 1 roller and the die is 14.30mm-14.40mm, the clearance between the No. 2 roller and the die is 12.20mm-12.30mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 70mm / min-75mm / min;

[0015] For the third pass, the gap between the No. 1 roller and the die is 10.90mm-11.05mm, the gap between the No. 2 roller and the die is 9.05mm-9.10mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 60mm / min-70mm / min;

[0016] For the 4th pass, the gap between the No. 1 roller and the die is 7.80mm-7.90mm, the gap between the No. 2 roller and the die is 7.00mm-7.10mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 70mm / min-80mm / min.

[0017] Further, in step 3, the inner diameter of the tube blank is 350mm-450mm, and the closing spinning adopts a combined trajectory, which includes 3 groups, as follows:

[0018] In the first group of trajectories, the forward spinning process is used to spin the end face of the tube blank extending out of the fixture into a cone with a cone angle of 45°-60°; the spinning passes are 8-12 passes, the single-pass spinning wheel pressing amount is 2mm-3mm, and the subsequent passes increase gradually, with an increase of 3mm-4mm per pass; the starting temperature is 160-200℃, and based on 2 passes, the ignition and shutdown are repeated in a cycle, that is, the first 2 passes are ignited for compensation heating, followed by 2 passes to stop the compensation heating, and then 2 passes to continue ignition for compensation heating; the temperature of the first group of trajectories throughout the entire spinning process does not exceed 230℃;

[0019] The second set of tracks adopts the reverse spinning process to pile up and thicken the tapered end formed by the first set of tracks; the spinning passes are 6-8 passes, the effective displacement of the tapered end in a single pass is 5mm-8mm, and compensatory heating is performed throughout the rotation. The heating position is 60mm-100mm away from the tapered end. The temperature of the second set of tracks does not exceed 280℃ throughout the rotation.

[0020] The third set of trajectories uses a forward spinning process to spin the tube blank that has undergone the second set of trajectories into a preset shape, that is, a formed ellipsoidal head + nozzle contour; the spinning passes are 8-10 passes, and 3 passes are used as a benchmark, and the ignition and shutdown are repeated. The temperature of the third set of trajectories during the entire spinning process does not exceed 320°C.

[0021] Furthermore, in step five, when mechanical thinning is performed, first, multiple points are evenly selected on the lining blank, and the selected points are scanned to outline the outer contour of the lining blank in real time; then the wall thickness of each point is detected, and the inner surface contour of the lining blank is reversed and outlined in real time through the wall thickness, which is used as a processing reference.

[0022] Furthermore, in step five, when mechanical thinning is performed, a plurality of points are first evenly selected on the lining blank, with the number of points being more than 3,000, covering the entire outer surface of the lining blank.

[0023] Furthermore, in step 5, the mechanical thinning process is divided into three stages, namely, rough machining, semi-finishing, and finishing, as follows:

[0024] Rough machining is done by turning, with a turning amount of 3mm-4mm;

[0025] Semi-finishing uses a combination of turning and milling, with a turning amount of 1mm-2mm; then the area where the measured wall thickness deviates from the theoretical value by more than +0.30mm is marked, and the marked area is milled to control the wall thickness deviation within +0.30mm;

[0026] The finishing process is carried out by milling, with a milling volume of 0.5mm-0.8mm. The wall thickness is monitored in real time during the milling process until the wall thickness deviation in all areas is ≤0.20mm.

[0027] Furthermore, after the machining is completed, the aluminum alloy lining is polished as a whole, and the polishing amount is 0.01mm-0.02mm.

[0028] The advantages of the present invention compared with the prior art are:

[0029] (1) The present invention adopts a multi-pass thinning and spinning method to prepare a closed tube blank, adopts a combined trajectory for closing spinning, and adopts a process combining turning and milling with milling as the main method to thin the wall thickness. At the same time, the above three links are coordinated and controlled to achieve high-precision preparation of a thin-walled seamless aluminum alloy lining with a large aspect ratio. The inner surface of the lining has no defects such as wrinkles and cracks, and the wall thickness deviation (the difference between the maximum wall thickness and the minimum wall thickness measured) is ≤0.20mm.

[0030] (2) The present invention prepares the closed tube blank by rolling and spinning, reasonably matches the offset of the double spinning wheels, and combines the coordinated design of the spinning passes, gap design, feed speed, spindle speed, etc. to ensure that the wall thickness deviation of the prepared closed tube blank is ≤0.30mm, laying the foundation for ensuring the uniformity of the lining wall thickness.

[0031] (3) The present invention adopts a combination of trajectories for closing spinning. The increasing pressing amount of the first group of trajectories helps to quickly close the diameter. The thickening of the second group of trajectories helps to ensure the wall thickness at the R corner of the liner nozzle. The repeated ignition and shutdown compensation heating method of the first and third groups of trajectories helps to suppress the heating rate of the entire closing spinning process, which can not only ensure the smooth flow of materials during the closing spinning process and avoid defects such as wrinkles and microcracks on the inner surface (especially near the R corner of the nozzle); but also eliminate the abnormal grain growth caused by excessive lining temperature.

[0032] (4) The present invention adopts point scanning + wall thickness reverse estimation to outline the inner and outer contours of the lining blank in real time, ensuring the reliability of the processing benchmark, effectively avoiding local processing deviations caused by the deviation between the theoretical and actual contours, and helping to ensure the uniformity of the lining wall thickness.

[0033] (5) The present invention adopts staged mechanical thinning, combining turning and milling with milling as the main method, and real-time monitoring of wall thickness during the processing process, which helps to ensure the uniformity of the lining wall thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0035] Figure 1 This is a schematic diagram of the thin spinning clamping of the present invention;

[0036] Figure 2 It is a schematic diagram of the closed tube blank formed by rolling thinning of the present invention;

[0037] Figure 3 It is a schematic diagram of the contour change during the closing spinning process of the present invention;

[0038] Figure 4 This is a schematic diagram of the lining blank of the present invention;

[0039] Figure 5 This is a schematic diagram of the inner lining contour drawn by scanning points in the present invention;

[0040] Figure 6 The present invention is a flow chart of the method for controlling the uniformity of the wall thickness of a thin-walled seamless aluminum alloy lining with a large aspect ratio. DETAILED DESCRIPTION

[0041] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0042] The present invention proposes a method for controlling the uniformity of the wall thickness of a thin-walled seamless aluminum alloy lining with a large aspect ratio. Figure 6 As shown, the following steps are included:

[0043] Step 1: Mount the aluminum alloy tube 1 on the double-wheel CNC spinning machine. Figure 1 As shown, a staggered spinning method (two spinning wheels have a spacing along the axial direction of the spinning core mold) is adopted, and a tube blank 2 for closing is prepared through four passes, as shown in FIG. Figure 2 shown.

[0044] The offset is 6-10mm, and all four passes are cold spinning and positive spinning. The front roller is defined as No. 1, and the lagging roller is defined as No. 2, that is, roller No. 1 is 6-10mm ahead of roller No. 2. The specific forming process is as follows:

[0045] In the first pass, the gap between the No. 1 roller and the die is 16.10-16.20 mm, the gap between the No. 2 roller and the die is 14.50-14.60 mm, the spindle speed is 75-80 rap / min, and the roller feed speed is 70-80 mm / min;

[0046] For the second pass, the gap between the No. 1 roller and the die is 14.30-14.40 mm, the gap between the No. 2 roller and the die is 12.20-12.30 mm, the spindle speed is 75-80 rap / min, and the roller feed speed is 70-75 mm / min;

[0047] For the third pass, the gap between the No. 1 roller and the die is 10.90-11.05 mm, the gap between the No. 2 roller and the die is 9.05-9.10 mm, the spindle speed is 75-80 rap / min, and the roller feed speed is 60-70 mm / min;

[0048] For the 4th pass, the clearance between the No. 1 roller and the die is 7.80-7.90 mm, the clearance between the No. 2 roller and the die is 7.00-7.10 mm, the spindle speed is 75-80 rap / min, and the roller feed speed is 70-80 mm / min;

[0049] The whole process of preparing the closed tube blank 2 by staggered spinning is strong spinning, and a support device is placed 80-100mm away from the starting position of spinning to lift the spinning mold 3 to avoid the "lower head effect" of the spinning mold 3. The wall thickness deviation of the closed tube blank 2 prepared by staggered spinning is ≤0.30mm.

[0050] Step 2, annealing the tube blank 2 that has undergone thinning and spinning;

[0051] Step 3: Mount the annealed tube 2 on the fixture of the special end-spinning equipment and extend it out of the end face of the fixture by a certain length (250-270 mm), with a roundness jump of <0.3 mm. The end-spinning adopts a combined trajectory until the tube 2 is spun to a preset shape.

[0052] The first set of trajectories uses a positive spinning process to spin the tube blank 2 extending out of the end face of the fixture into a cone, such as Figure 3 As shown, the cone angle is 45-60°; the number of spinning passes is 8-12, the pressing amount of the spinning wheel in a single pass is 2-3mm, and the subsequent passes increase gradually, with an increase of 3-4mm per pass; the starting temperature is 160-200℃, and based on 2 passes, the ignition and shutdown are repeated in a cycle, that is, the first 2 passes are ignited for compensation heating, followed by 2 passes to stop the compensation heating, and then 2 passes to continue ignition for compensation heating..., the temperature of the first group of trajectories throughout the entire spinning process does not exceed 230℃;

[0053] The second set of trajectories uses a reverse rotation process to pile up and thicken the tapered end formed by the first set of trajectories, such as Figure 3 As shown; the spinning passes are 6-8 passes, the effective displacement of the tapered end in a single pass (contraction along the axis) is 5-8mm, compensatory heating is performed throughout the entire rotation, the heating position is 60-100mm away from the tapered end, and the temperature of the second set of tracks throughout the entire rotation does not exceed 280°C;

[0054] The third set of trajectories adopts a positive spinning process to spin the tube blank 2 after the second set of trajectories to a preset shape, that is, to form an ellipsoidal head + nozzle profile; the spinning passes are 8-10 passes, and 3 passes are used as a benchmark, and the ignition and shutdown are repeated. The temperature of the third set of trajectories during the entire spinning process does not exceed 320°C;

[0055] Turn and clamp the other end of the tube blank 2, and repeat the above three sets of trajectories;

[0056] The formed liner blank 4 is cut, and its inner surface forming quality is good, without defects such as wrinkles and cracks, the inner surface contour has no deviation, and the R angle position of the nozzle is significantly thickened.

[0057] Step 4: subjecting the liner blank 4 that has undergone the closing and spinning forming to T6 heat treatment;

[0058] Step 5: The lining blank 4 which has undergone T6 heat treatment, such as Figure 4 As shown, machining is performed;

[0059] First, 3600 points are evenly selected on the lining blank 4, and the selected points are scanned to outline the outer contour of the lining blank 4 in real time; then the wall thickness of the above 3600 points is detected, and the inner surface contour of the lining blank 4 is deduced in real time through the wall thickness, which is used as the processing reference. Figure 5 shown.

[0060] The mechanical thinning process is divided into three stages, namely rough machining, semi-finishing and finishing.

[0061] Rough machining is done by turning, with a turning amount of 3-4mm;

[0062] Semi-finishing uses a combination of turning and milling, with a turning amount of 1-2mm. Then, the areas where the measured wall thickness deviates from the theoretical value by more than +0.30mm are marked, and these locations are milled to control the wall thickness deviation within +0.30mm.

[0063] The finishing process is done by milling, with a milling amount of 0.5-0.8mm. The wall thickness is monitored in real time during the milling process until the wall thickness deviation of all regions is ≤0.20mm. Then the lining 5 is polished as a whole, with a polishing amount of 0.01-0.02mm.

[0064] Example 1

[0065] A specific embodiment is given below. In this embodiment, the cylindrical liner is made of 6061 aluminum alloy, with a length of 1288 mm, a straight section length of 866 mm, an inner diameter of 400 mm, and a wall thickness of 2 mm. The head is ellipsoidal, the major semi-axis of the inner surface of the head is 200 mm, the minor semi-axis is 100 mm, the major semi-axis of the outer surface of the head is 202 mm, the minor semi-axis is 105 mm, the nozzle length is 56 mm, the nozzle outer circle is Φ52 mm, the nozzle inner hole is Φ28 mm, and the R angle thickness is 14 mm. The following is a specific process of the method for controlling the uniformity of the wall thickness of a thin-walled seamless aluminum alloy liner with a large aspect ratio:

[0066] Step 1: Mount the aluminum alloy tube on a double-wheel CNC spinning machine, adopt a staggered spinning method (there is a distance between the two wheels along the axial direction of the spinning core mold), and go through 4 passes to prepare a tube blank for closing.

[0067] The offset is 8mm, and all 4 passes are cold spin and positive spin;

[0068] In the first pass, the gap between the No. 1 roller and the die is 16.20 mm, the gap between the No. 2 roller and the die is 14.50 mm, the spindle speed is 75 rap / min, and the roller feed speed is 70 mm / min;

[0069] For the second pass, the gap between the No. 1 roller and the die is 14.30 mm, the gap between the No. 2 roller and the die is 12.20 mm, the spindle speed is 75 rap / min, and the roller feed speed is 75 mm / min;

[0070] For the third pass, the gap between the No. 1 roller and the die is 10.90 mm, the gap between the No. 2 roller and the die is 9.05 mm, the spindle speed is 75 rap / min, and the roller feed speed is 60 mm / min;

[0071] In the 4th pass, the gap between the No. 1 roller and the die is 7.90 mm, the gap between the No. 2 roller and the die is 7.00 mm, the spindle speed is 80 rap / min, and the roller feed speed is 70 mm / min;

[0072] The whole process of preparing the closed tube blank by staggered spinning is high-power spinning. At the same time, a support device is placed 90mm away from the starting position to support the spinning mold to avoid the "lower head effect" of the spinning mold. The wall thickness deviation of the closed tube blank prepared by staggered spinning is ≤0.25mm. The support device includes a base and a support roller. The support roller contacts the circumferential end face of the spinning mold and moves with the rotation of the spinning mold to support the spinning mold.

[0073] Step 2: annealing the tube blank after thinning and spinning;

[0074] Step 3: Mount the annealed tube on the fixture of the special end-spinning equipment, and extend it out of the end face of the fixture by a certain length (260mm), with a roundness jump of less than 0.3mm. The end-spinning adopts a combined trajectory until the tube is spun to a preset shape.

[0075] In the first group of trajectories, the forward spinning process is used to spin the end face of the tube blank extending out of the fixture into a cone with a cone angle of 45°; the number of spinning passes is 12, and the reduction of the spinning wheel in a single pass is 2mm, and the subsequent passes increase gradually, with an increase of 3mm per pass; the starting temperature is 160-200℃, and based on 2 passes, the ignition and shutdown are repeated in a cycle, that is, the first 2 passes are ignited for compensation heating, followed by 2 passes to stop the compensation heating, and then 2 passes to continue ignition for compensation heating. The temperature of the first group of trajectories does not exceed 215℃ throughout the entire spinning process;

[0076] The second set of tracks adopts the reverse spinning process to pile up and thicken the tapered end formed by the first set of tracks; the spinning passes are 6, and the effective displacement (contraction along the axis) of the tapered end in a single pass is 8mm. Compensation heating is performed throughout the rotation, and the heating position is 70mm away from the tapered end. The temperature of the second set of tracks does not exceed 260℃ throughout the rotation;

[0077] The third set of trajectories adopts the forward spinning process to spin the tube blank after the second set of trajectories to the preset shape, that is, the ellipsoidal head + nozzle profile; the spinning passes are 9 passes, and the ignition and shutdown are repeated based on 3 passes. The temperature of the third set of trajectories does not exceed 300℃ during the entire spinning process;

[0078] Turn and clamp the other end of the tube blank, and repeat the above three sets of trajectories;

[0079] Step 4: subjecting the liner blank 4 that has undergone the closing and spinning forming to T6 heat treatment;

[0080] Step 5: Machining the lining blank that has undergone T6 heat treatment;

[0081] First, 3600 points are evenly selected on the lining blank, and the selected points are scanned to outline the outer contour of the lining blank in real time; then the wall thickness of the above 3600 points is detected, and the inner surface contour of the lining blank is reversed and outlined in real time through the wall thickness, which is used as the processing reference.

[0082] The mechanical thinning process is divided into three stages, namely rough machining, semi-finishing and finishing.

[0083] The rough machining is done by turning, with a turning amount of 3.5 mm;

[0084] Semi-finishing uses a combination of turning and milling, with a turning amount of 1mm. Then, the areas where the measured wall thickness deviates from the theoretical value by more than +0.30mm are marked, and these locations are milled to control the wall thickness deviation within +0.30mm.

[0085] The finishing process is carried out by milling with a milling volume of 0.6mm. The wall thickness is monitored in real time during the milling process until the wall thickness deviation in all areas is ≤0.20mm.

[0086] Then the lining is polished as a whole with a polishing amount of 0.01-0.02mm.

[0087] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy lining with a large aspect ratio, characterized in that: include: Step 1: Mount the aluminum alloy tube on a double-wheel CNC spinning machine, adopt a staggered spinning method, and go through multiple passes to prepare a tube blank for closing; Step 2: annealing the tube blank after thinning and spinning; Step 3: Clamp the annealed tube blank onto the fixture of the closing spinning equipment, extend the tube blank out of the fixture end face, and use a combined trajectory to close the tube blank until the tube blank is spun into a preset shape to form a liner blank; Step 4: heat treating the lining blank; Step 5: Mechanically process the heat-treated liner blank to obtain a formed aluminum alloy liner.

2. The method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy liner with a large aspect ratio according to claim 1 is characterized in that: In step one, staggered spinning is used to prepare the closed tube blank, and a supporting device is placed 80mm-100mm away from the starting position of spinning to lift the spinning die. The wall thickness deviation of the prepared closed tube blank is ≤0.30mm.

3. The method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy liner with a large aspect ratio according to claim 2 is characterized in that: In step 1, 4 passes are used to prepare the tube blank for closing, and all 4 passes are cold spinning and positive spinning; the front roller is defined as No. 1 and the lagging roller is defined as No. 2, that is, roller No. 1 is 6mm-10mm ahead of roller No. 2; the inner diameter of the tube blank for closing is 350mm-450mm, the length is 1.3m-1.5m, and the wall thickness is 6mm-8mm. The specific forming process is as follows: In the first pass, the gap between the No. 1 roller and the die is 16.10mm-16.20mm, the gap between the No. 2 roller and the die is 14.50mm-14.60mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 70mm / min-80mm / min; For the second pass, the clearance between the No. 1 roller and the die is 14.30mm-14.40mm, the clearance between the No. 2 roller and the die is 12.20mm-12.30mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 70mm / min-75mm / min; For the third pass, the gap between the No. 1 roller and the die is 10.90mm-11.05mm, the gap between the No. 2 roller and the die is 9.05mm-9.10mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 60mm / min-70mm / min; For the 4th pass, the gap between the No. 1 roller and the die is 7.80mm-7.90mm, the gap between the No. 2 roller and the die is 7.00mm-7.10mm, the spindle speed is 75rap / min-80rap / min, and the roller feed speed is 70mm / min-80mm / min.

4. The method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy liner with a large aspect ratio according to claim 1 is characterized in that: In step 3, the inner diameter of the tube blank is 350mm-450mm, and the closing spinning adopts a combined trajectory, which includes 3 groups, as follows: In the first group of trajectories, the forward spinning process is used to spin the end face of the tube blank extending out of the fixture into a cone with a cone angle of 45°-60°; the spinning passes are 8-12 passes, the single-pass spinning wheel pressing amount is 2mm-3mm, and the subsequent passes increase gradually, with an increase of 3mm-4mm per pass; the starting temperature is 160-200℃, and based on 2 passes, the ignition and shutdown are repeated in a cycle, that is, the first 2 passes are ignited for compensation heating, followed by 2 passes to stop the compensation heating, and then 2 passes to continue ignition for compensation heating; the temperature of the first group of trajectories throughout the entire spinning process does not exceed 230℃; The second set of tracks adopts the reverse spinning process to pile up and thicken the tapered end formed by the first set of tracks; the spinning passes are 6-8 passes, the effective displacement of the tapered end in a single pass is 5mm-8mm, and compensatory heating is performed throughout the rotation. The heating position is 60mm-100mm away from the tapered end. The temperature of the second set of tracks does not exceed 280℃ throughout the rotation. The third set of trajectories uses a forward spinning process to spin the tube blank that has undergone the second set of trajectories into a preset shape, that is, a formed ellipsoidal head + nozzle contour; the spinning passes are 8-10 passes, and 3 passes are used as a benchmark, and the ignition and shutdown are repeated. The temperature of the third set of trajectories during the entire spinning process does not exceed 320°C.

5. The method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy liner with a large aspect ratio according to claim 1 is characterized in that: In step five, when mechanical thinning is performed, multiple points are first evenly selected on the lining blank, and the selected points are scanned to outline the outer contour of the lining blank in real time; then the wall thickness of each point is detected, and the inner surface contour of the lining blank is reversed through the wall thickness and outlined in real time, which is used as the processing reference.

6. The method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy liner with a large aspect ratio according to claim 5 is characterized in that: In step five, when mechanical thinning is performed, firstly, multiple points are evenly selected on the lining blank, with the number of points being more than 3,000, covering the entire outer surface of the lining blank.

7. The method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 1 is characterized in that: In step 5, the mechanical thinning process is divided into three stages, namely rough machining, semi-finishing, and finishing, as follows: Rough machining is done by turning, with a turning amount of 3mm-4mm; Semi-finishing uses a combination of turning and milling, with a turning amount of 1mm-2mm; then the area where the measured wall thickness deviates from the theoretical value by more than +0.30mm is marked, and the marked area is milled to control the wall thickness deviation within +0.30mm; The finishing process is carried out by milling, with a milling volume of 0.5mm-0.8mm. The wall thickness is monitored in real time during the milling process until the wall thickness deviation in all areas is ≤0.20mm.

8. The method for controlling the wall thickness uniformity of a thin-walled seamless aluminum alloy liner with a large aspect ratio according to claim 1 is characterized in that: After the machining is completed, the aluminum alloy lining is polished as a whole, and the polishing amount is 0.01mm-0.02mm.

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