Aluminum alloy thin-wall seamless liner and its precision spinning forming method and application

Abstract

An aluminum alloy thin-walled seamless liner and its precision spinning forming method and application. The present invention belongs to the field of aluminum alloy forming technology. The purpose of the present invention is to solve the technical problems of the current aluminum alloy liner parts, such as the imperfect overall forming process and poor forming accuracy. The liner of the present invention includes an integrally formed bottle mouth and bottle body, and the bottom of the bottle body is provided with a cylindrical boss integrally formed with the bottle body, with a height of 10 to 25 mm, a diameter of Φ15 to 30 mm, and a roundness of 0.05 mm. The method of the present invention: first perform a single-pass shear spinning; then perform multiple passes of general spinning; then perform multiple passes of closing spinning; finally, perform solid solution aging strengthening and precision machining to cut into the final parts. The liner of the present invention is used in the field of aerospace, and the method of the present invention is used to form thin-walled seamless one-piece bottles or cans.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy forming, and in particular relates to an aluminum alloy thin-wall seamless liner and a precision spinning forming method and application thereof. Background Art

[0002] Gas cylinders are widely used in industries such as industry, healthcare, firefighting, and household applications. Aerospace cylinders, for example, are both valuable and challenging. These include oxygen tanks, power sources, liquid oxygen cylinders, and power and propellant storage devices on board aircraft. The harsh and demanding aerospace environment places higher demands on the cylinders' sealing properties and pressure resistance. High-pressure gas cylinders have evolved from simple pure metal cylinders to composite wrapped cylinders.

[0003] Composite-wrapped gas cylinders typically consist of a fiber-wound material and a metal liner. Compared to traditional steel cylinders, these cylinders combine the high specific strength of composite materials with the airtightness and corrosion resistance of a metal liner. This significantly improves the cylinder's performance, providing a higher specific strength and preventing sudden damage from overload. The liner is typically made of a metal material with excellent strength and rigidity, such as titanium alloy or aluminum alloy, to effectively protect the high-pressure gas or liquid within the cylinder and enhance its safety and reliability.

[0004] Compared with other metal materials, aluminum alloy has the characteristics of good formability, low cost, low density and excellent resistance to intergranular corrosion. It has now become an ideal material for metal liners. Aluminum alloy metal liners have the advantages of excellent air tightness, low density, high specific strength, long service life and high stability. In addition, aluminum alloy has excellent processing performance and can be formed in one piece to form a weldless lining, which can minimize the potential fatigue damage and cost.

[0005] Liner components must be designed to withstand internal pressure, maintain a sufficient volume, and maintain a total weight no greater than a certain value. They also require a long shelf life, no welds, and strict internal surface accuracy and roughness requirements. Therefore, aluminum alloy liner components require a certain level of strength and strictly controlled wall thickness in straight sections. Due to the significant difference in wall thickness and diameter between the bottle body and the neck (the thin-walled, large diameter bottle body and the thick-walled, small diameter neck), forming these parts using traditional forging and internal high-pressure methods is difficult. However, the closed boss structure makes it difficult to meet product requirements using traditional neck-spinning processes. Summary of the Invention

[0006] The purpose of the present invention is to solve the technical problems of the current aluminum alloy liner parts, such as the imperfect overall forming process and poor forming accuracy, and to provide an aluminum alloy thin-walled seamless liner and its precision spinning forming method and application.

[0007] The technical solutions of the present invention are as follows:

[0008] One of the purposes of the present invention is to provide an aluminum alloy thin-walled seamless liner, comprising an integrally formed bottle mouth and bottle body, characterized in that a cylindrical boss integrally formed with the bottle body is provided at the bottom of the bottle body, with a height of 10 to 25 mm, a diameter of Φ15 to 30 mm, and a roundness of 0.05 mm.

[0009] It is further specified that the nominal outer diameter of the straight cylindrical section of the bottle body is Φ90~130mm, and the inner liner volume is 0.6~3.0L.

[0010] It is further defined that the wall thickness of the straight section of the bottle body is 0.7 to 1.5 mm, and the wall thickness of the elliptical end surface is 1.2 to 2.0 mm.

[0011] It is further defined that the length of the bottle mouth is 15 to 35 mm, the outer side of the bottle mouth is threaded, the thread specification is M12 to 20, the inner diameter of the bottle mouth is Φ6 to 8 mm, and the roundness of the center hole is 0.02 mm.

[0012] A second object of the present invention is to provide a precision spinning method for a thin-walled seamless aluminum alloy liner, the method being carried out in the following steps:

[0013] (1) Fix the aluminum alloy sheet on the mandrel of the spinning machine, perform a shear spinning in a heated state, and form an open bowl-shaped part with a certain cone angle. Stop heating, remove the workpiece after cooling, and perform annealing heat treatment;

[0014] (2) fixing the workpiece obtained in step (1) on a cylindrical mandrel, performing multiple passes of conventional spinning in a heated state until a straight cup-shaped part with a taper angle of 0 is obtained, stopping heating, removing the workpiece after cooling, and performing annealing heat treatment;

[0015] (3) cutting the bottom of the cup-shaped part obtained in step (2) to obtain a workpiece having a boss structure;

[0016] (4) Fixing the boss end of the workpiece obtained in step (3) on a fixture, performing multiple-pass closing spinning on the open end of the cup-shaped part under heating, stopping heating, removing the workpiece after cooling, and performing solid solution aging heat treatment to obtain an inner liner blank;

[0017] (5) Fine turning the inner liner blank obtained in step (4) to obtain an aluminum alloy inner liner.

[0018] It is further defined that in step (1), the cone angle is 30° to 75°, and the wall thickness of the bowl-shaped part is 5 to 6 times the wall thickness of the straight cylindrical section of the bottle body.

[0019] It is further defined that the number of ordinary spinning passes in step (2) is 8 to 12 passes.

[0020] It is further defined that the wall thickness of the cup-shaped part in step (2) is 2 to 3 times the wall thickness of the straight cylindrical section of the bottle body.

[0021] It is further defined that the diameter reduction in the closing spinning pass in step (4) is not greater than the radius of the spinning wheel corner.

[0022] It is further defined that in step (4), the solution temperature is 525-575°C, the solution time is 15-45 min, the aging temperature is 180-300°C, the aging time is 4-12 h, and the heating rates in the solution and aging stages are both 5-20°C / min.

[0023] It is further defined that before the spinning process in steps (1), (2) and (4), the core shaft and the spinning wheel of the spinning machine are preheated to 120-200°C.

[0024] It is further defined that the heating method in steps (1), (2) and (4) is oxygen / propane flame heating.

[0025] A third object of the present invention is to provide an aluminum alloy thin-walled seamless liner for use in the aerospace field.

[0026] A fourth object of the present invention is to provide a forming method for forming a thin-walled seamless one-piece bottle or can.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The present invention provides a precision spinning forming method for an aluminum alloy seamless liner, which generally adopts a spinning processing method. Starting from a plate, parts of required shape and size are formed in sequence according to the processes of shear spinning, ordinary spinning, and closing spinning, thereby solving the overall manufacturing process of thin-walled aluminum alloy gas cylinder liner parts. The processing process has the characteristics of low energy consumption, low pollution, high material utilization rate, stable process, and low cost. The formed aluminum alloy gas cylinder liner parts have the advantages of safety and reliability, large volume, good performance, thin wall thickness, high precision, and no welds, providing an efficient, economical, and green forming solution for similar parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the aluminum alloy thin-walled seamless liner structure of the present invention;

[0030] Figure 2 Schematic diagram of the structure of the open bowl-shaped piece obtained in step (2) of the forming method of the present invention;

[0031] Figure 3 Schematic diagram of the structure of the closed cup-shaped part obtained in step (3) of the forming method of the present invention;

[0032] Figure 4This is a photo of the aluminum alloy thin-walled seamless liner obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present disclosure. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0034] In the description of the present disclosure, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," and the like, indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely for the purpose of facilitating the description of the present disclosure and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present disclosure. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the present disclosure, "plurality" means two or more, unless otherwise expressly and specifically defined.

[0035] In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, removable, or integral connections; mechanical, electrical, or intercommunication connections; direct or indirect connections through an intermediary; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on specific circumstances.

[0036] In this disclosure, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a lower level than the second feature.

[0037] The disclosure below provides many different embodiments or examples for realizing different structures of the present disclosure. In order to simplify the disclosure of the present disclosure, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present disclosure. In addition, the present disclosure may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present disclosure provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0038] The preferred embodiments of the present disclosure are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0039] See also Figure 1 As shown, the present invention provides an aluminum alloy thin-walled seamless liner, including an integrally formed bottle mouth and bottle body, the bottle body consisting of five sections, a middle straight cylindrical section, two elliptical end surfaces, and a transition zone between the middle straight cylindrical section and the two elliptical end surfaces, characterized in that: a cylindrical boss integrally formed with the bottle body is provided at the bottom of the bottle body, with a height of 10 to 25 mm, a diameter of Φ15 to 30 mm, and a roundness of 0.05 mm.

[0040] In some optional embodiments, the nominal outer diameter of the straight section of the bottle body is Φ90-130 mm, the total length of the liner is 150-400 mm, the volume of the liner is 0.6-3.0 L, and the total weight of the liner is 120-500 g.

[0041] The length of the straight tube section is 60 to 250 mm, and the wall thickness of the straight tube section is 0.7 to 1.5 mm.

[0042] The wall thickness of the elliptical end face is 1.2 to 2.0 mm, the semi-major axis of the outer profile of the elliptical end face connected to the bottle mouth is 45 to 65 mm, the semi-minor axis is 25 to 40 mm, the semi-major axis of the inner profile is 44.3 to 63.5 mm, and the semi-minor axis is 23 to 38 mm; the semi-major axis of the outer profile of the elliptical end face connected to the boss is 45 to 65 mm, the semi-minor axis is 25 to 40 mm, the semi-major axis of the inner profile is 44.3 to 63.5 mm, and the semi-minor axis is 24.3 to 38.5 mm.

[0043] The length of the transition zone is 15 mm to 30 mm, and the wall thickness of the transition zone is 1.2 to 2.0 mm.

[0044] The length of the bottle mouth is 15 to 35 mm, the outside of the bottle mouth is threaded, the thread specification is M12 to 20, the inner diameter of the bottle mouth is Φ6 to 8 mm, the roundness of the center hole is 0.02 mm, the inner surface roughness of the bottle mouth is less than Ra 0.8 μm, and the roughness of the rest of the bottle mouth except the inner surface is less than Ra 3.2 μm.

[0045] The outer end face of the boss has a 2.5mm A-type center hole for machining and clamping.

[0046] See also Figure 2-3 As shown, the present invention provides a precision spinning forming method for preparing the above-mentioned aluminum alloy thin-walled seamless liner, which is carried out in the following steps:

[0047] Step (1): determining the incoming state of the aluminum alloy sheet, annealing the aluminum alloy sheet, and processing the original aluminum alloy sheet into a circular sheet with a thickness of 20 to 30 mm and a diameter of Φ150 to 300 mm according to the size specifications of the formed parts;

[0048] Spray a layer of graphite lubricant evenly on the spindle of the spinning machine to reduce the friction between the blank and the spindle during the forming process. Clamp the circular sheet on the spindle and start the spindle of the spinning machine to make the sheet rotate with the spindle.

[0049] Use flame heating to preheat the mandrel, sheet and roller, controlling the temperature of the mandrel and roller at 120-200°C, and the temperature of the sheet at 280-350°C;

[0050] Start the preset program of the spinning machine and perform shear spinning. During the shear spinning process, the temperature of the sheet forming zone is always kept at 280-350°C. The spinning equipment adopts a commercially available double-wheel CNC spinning machine with a mirror function. The spinning method is single-wheel shear spinning. The gap value between the wheel and the mandrel is set to 10-15mm, the spindle speed is 100r / min, the mandrel taper angle is 30°-75°, the mandrel length is 1.2-1.5 times the length of the formed part, the spinning feed ratio is 2-7.5mm / r, and the spinning machine is stopped at the end of forming. After the workpiece cools to room temperature, it is removed to obtain an open bowl-shaped part with a taper angle of 30°-75°. The bowl wall thickness (0.5δ) of the bowl-shaped part is 5-6 times the wall thickness of the straight tube section of the bottle body (structure as shown in FIG. Figure 2 shown);

[0051] Place the workpiece in a vacuum annealing furnace and heat it with the furnace at a heating rate of 5-20℃ / min. Start the insulation timer when the temperature reaches 300-400℃. Wait for 1-2 hours and then turn off the power. Take out the workpiece after cooling it with the furnace.

[0052] Step (2): spray a layer of graphite lubricant evenly on the cylindrical core shaft to reduce the friction between the workpiece and the core shaft during the forming process. The length of the core shaft is 1.2 to 1.5 times the length of the workpiece after forming. Then, the workpiece obtained in step (1) is fixed on the core shaft using the tail of the spinning machine, and the spindle of the spinning machine is started to rotate the workpiece with the spindle.

[0053] Use flame heating to preheat the mandrel, workpiece and roller, control the temperature of the mandrel and roller at 120-200℃, and control the temperature of the workpiece at 280-350℃;

[0054] Start the preset program of the spinning machine and perform ordinary spinning. During the ordinary spinning process, the temperature of the workpiece forming zone is always maintained at 280-350°C. The spinning equipment uses a commercially available double-wheel CNC spinning machine with a mirror function. The spinning method is single-wheel multi-pass ordinary spinning, the spinning passes are 8-12 times, the spindle speed is 100r / min, and the feed ratio during spinning is 2-7.5mm / r. After forming, a straight cup-shaped part with a taper angle of 0 is obtained (structure as shown in FIG. Figure 3 As shown in the figure, the wall thickness of the cup-shaped part is 2 to 3 times the wall thickness of the straight section of the bottle body. Stop the spinning machine, wait for the workpiece to cool to room temperature, and then use the unloading plate matched with the mandrel to push the workpiece out.

[0055] Place the workpiece in a vacuum annealing furnace and heat it with the furnace at a heating rate of 5-20℃ / min. Start the insulation timer when the temperature reaches 300-400℃. Wait for 1-2 hours and then turn off the power. Take out the workpiece after cooling it with the furnace.

[0056] Step (3): machining the workpiece obtained in step (2) using a high-precision CNC lathe, turning the straight cylindrical section and the elliptical end surface of the cup-shaped part to a wall thickness of 2 to 4.5 mm according to the contour of the inner surface, and forming a boss structure with a height of 10 to 25 mm, a diameter of Φ15 to 30 mm, and a roundness of 0.05 mm;

[0057] High-precision CNC lathes are used for fixed-length processing, so that the length of the straight section of the cup-shaped part is 1.2 times the sum of the lengths of the bottle body and the curved generatrix of the bottle mouth of the liner, to prevent instability caused by the excessive length of the spun bottle mouth;

[0058] The inner surface of the workpiece is machined using a CNC lathe with a maximum inner diameter feed of 0.5 mm, and an inner surface is turned out that is consistent with the shape, contour and features of the straight section and transition zone of the aluminum alloy liner part;

[0059] The workpiece is cleaned with an ultrasonic cleaner and dried with a drying device after cleaning.

[0060] Step (4): placing the workpiece obtained in step (3) into a split-type hollow spindle with one end closed. The split-type hollow spindle has two parts connected by bolts. When clamping, the end face of the workpiece boss is in close contact with the inner end face of the hollow spindle. Start the spindle of the spinning machine to rotate the workpiece together with the hollow spindle.

[0061] Use flame heating to preheat the mandrel and the roller, controlling the temperature of the mandrel and the roller at 120-200°C. At the same time, preheat the free end of the workpiece (the part exposed outside the hollow spindle) and control the temperature of the workpiece at 280-350°C.

[0062] The preset program of the spinning machine is started to perform closing spinning. During the closing spinning process, the temperature of the workpiece forming zone is always maintained at 280-350°C. The spinning equipment adopts a commercially available double-wheel CNC spinning machine with a mirroring function. The spinning method is a multi-pass closing spinning process in which the double wheels are used alternately, with a total of 11-15 passes. The roller corner radii are 5 mm and 8 mm respectively. The spindle speed during spinning is 100 r / min, and the feed ratio during spinning is 1-5 mm / r. As the number of passes increases, the feed ratio gradually decreases from 5 mm / r to 1 mm / r to form an aluminum alloy liner formed part. The heating is stopped, and after the workpiece cools to room temperature, the aluminum alloy liner formed part is removed from the hollow spindle.

[0063] The obtained aluminum alloy liner formed part is placed in a box furnace for heating at room temperature, with a heating rate set at 5-20°C / min and a solution temperature of 525-575°C. When the furnace temperature reaches the preset temperature, the workpiece is kept warm for 15-45 minutes. After the timer expires, the workpiece is taken out and quenched with water, and the box furnace power is turned off.

[0064] After solution treatment, the workpiece is placed in an aging furnace, the heating rate is set to 5-20℃ / min, and the aging treatment is carried out at 180-300℃ for 4-12 hours. After the aging is completed, the power is turned off, and the workpiece is taken out after cooling to room temperature in the furnace to obtain an aluminum alloy inner liner billet.

[0065] Step (5): Processing of the outer profile of the straight tube section and the elliptical end face: clamping the obtained aluminum alloy inner liner blank on a CNC lathe, and turning the outer diameter of the straight tube section and the outer profile of the elliptical end faces on both sides. At this time, the diameter of the boss is also processed;

[0066] The bottle mouth is processed by using a CNC lathe and special tooling for bottle mouth processing to cut the center hole and external thread of the bottle mouth to obtain the aluminum alloy inner liner parts;

[0067] Use high-pressure water spraying device to clean the aluminum alloy liner parts as a whole, remove the residual aluminum chips, cutting fluid and other pollutants that affect the surface finish;

[0068] Conduct finished product inspection on the processed aluminum alloy liner parts. Use a calibrated ultrasonic wall thickness gauge to measure the wall thickness of typical points of the aluminum alloy liner parts, and use an outside micrometer to measure the outside diameter of the straight section.

[0069] Use a high-precision balance to weigh the empty weight of the aluminum alloy liner parts, then slowly inject pure water into the liner to the bottle mouth, wait for it to stand, then weigh the full weight, and calculate the volume of the aluminum alloy liner parts;

[0070] Place the inner tank in alcohol to check for tightness, pass 1.2-1.5 MPa air pressure for 5-7 minutes, and no bubbles are generated.

[0071] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0072] Example 1: The aluminum alloy thin-walled seamless liner of this embodiment includes an integrally formed bottle mouth and bottle body. The bottle body is composed of five sections, a middle straight cylindrical section, elliptical end surfaces at both ends, and a transition zone between the middle straight cylindrical section and the elliptical end surfaces at both ends. It is characterized in that a cylindrical boss integrally formed with the bottle body is provided at the bottom of the bottle body, with a height of 20 mm, a diameter of Φ16 mm, and a roundness of 0.05 mm.

[0073] The nominal outer diameter of the straight section of the bottle body is Φ115mm, the total length of the inner liner is 200mm, the inner liner volume is 1.3L, and the total weight of the inner liner is 230g.

[0074] The length of the straight section is 90 mm, and the wall thickness of the straight section is 0.8 mm.

[0075] The wall thickness of the elliptical end face is 1.5mm. The semi-major axis of the outer surface of the elliptical end face connected to the bottle mouth is 58.5mm, the semi-minor axis is 34.5mm, the semi-major axis of the inner surface is 57mm, and the semi-minor axis is 33mm; the semi-major axis of the outer surface of the elliptical end face connected to the boss is 58.5mm, the semi-minor axis is 34mm, the semi-major axis of the inner surface is 57mm, and the semi-minor axis is 32.5mm.

[0076] The transition zone is 15 mm long and has a wall thickness of 1.5 mm.

[0077] The length of the bottle mouth is 35mm, and there is a thread on the outside of the bottle mouth with a thread specification of M20. The inner diameter of the bottle mouth is Φ8mm, the roundness of the center hole is 0.02mm, the inner surface roughness of the bottle mouth is less than Ra 0.8μm, and the roughness of the rest of the bottle mouth except the inner surface is less than Ra 3.2μm.

[0078] The outer end face of the boss has a 2.5mm A-type center hole for machining and clamping.

[0079] Example 2: The precision spinning method for preparing the aluminum alloy thin-walled seamless liner described in Example 1 is carried out according to the following steps:

[0080] Step (1): Determine the incoming material state of the aluminum alloy sheet, perform annealing treatment on the aluminum alloy sheet, and process the original aluminum alloy sheet into a circular sheet with a thickness of 20 mm and a diameter of Φ250 mm according to the size specifications of the formed part;

[0081] Spray a layer of graphite lubricant evenly on the spindle of the spinning machine to reduce the friction between the blank and the spindle during the forming process. Clamp the circular sheet on the spindle and start the spindle of the spinning machine to make the sheet rotate with the spindle.

[0082] Use flame heating to preheat the mandrel, sheet and roller, controlling the temperature of the mandrel and roller at 120-200°C, and the temperature of the sheet at 280-350°C;

[0083] The preset program of the spinning machine is started to perform shear spinning. During the shear spinning process, the temperature of the sheet forming zone is always maintained at 280-350°C. The spinning equipment uses a commercially available double-wheel CNC spinning machine with a mirroring function. The spinning method is single-wheel shear spinning with one pass. The gap between the wheel and the mandrel is set to 10 mm, the spindle speed is 100 r / min, the mandrel taper angle is 30°, the mandrel length is 1.5 times the length of the formed part, and the spinning feed ratio is 5 mm / r. The spinning machine is stopped when the forming is completed. After the workpiece cools to room temperature, it is removed to obtain an open bowl-shaped part with a taper angle of 30°. The bowl wall thickness of the bowl-shaped part is 6 times the wall thickness of the straight tube section of the bottle body.

[0084] Place the workpiece in a vacuum annealing furnace and heat it with the furnace at a heating rate of 10℃ / min. Start the insulation timer when the temperature reaches 360℃. Wait for 1.5 hours and then turn off the power. Take out the workpiece after cooling it with the furnace.

[0085] Step (2): spray a layer of graphite lubricant evenly on the cylindrical core shaft to reduce the friction between the workpiece and the core shaft during the forming process. The length of the core shaft is 1.2 times the length of the workpiece after forming. Then, the workpiece obtained in step (1) is fixed on the core shaft using the tail of the spinning machine, and the spindle of the spinning machine is started to rotate the workpiece with the spindle;

[0086] Use flame heating to preheat the mandrel, workpiece and roller, control the temperature of the mandrel and roller at 120-200℃, and control the temperature of the workpiece at 280-350℃;

[0087] Start the preset program of the spinning machine and perform ordinary spinning. During the ordinary spinning process, the temperature of the workpiece forming zone is always maintained at 280-350°C. The spinning equipment uses a commercially available double-wheel CNC spinning machine with a mirroring function. The spinning method is single-wheel multi-pass ordinary spinning, with 12 spinning passes. The spindle speed is 100 r / min and the feed ratio during spinning is 2 mm / r. After forming, a straight cylindrical cup-shaped part with a taper angle of 0 is obtained. The cup wall thickness of the cup-shaped part is 3 times the wall thickness of the straight cylindrical section of the bottle body. Stop the spinning machine, wait for the workpiece to cool to room temperature, and then use a stripper plate matched with the mandrel to push the workpiece out.

[0088] Place the workpiece in a vacuum annealing furnace and heat it with the furnace at a heating rate of 10℃ / min. Start the insulation timer when the temperature reaches 360℃. Wait for 1.5 hours and then turn off the power. Take out the workpiece after cooling it with the furnace.

[0089] Step (3): Use a high-precision CNC lathe to machine the workpiece obtained in step (2). According to the contour of the inner surface, the wall thickness of the straight cylindrical section and the elliptical end surface of the cup-shaped part is turned to 3.5 mm, and a boss structure with a height of 20 mm and a diameter of Φ16 mm is formed;

[0090] High-precision CNC lathes are used for fixed-length processing, so that the straight section of the cup-shaped part is 150mm long, to prevent instability caused by the excessive length of the neck-spinning bottle mouth;

[0091] The inner surface of the workpiece is machined using a CNC lathe with a maximum inner diameter feed of 0.5 mm, and an inner surface is turned out that is consistent with the shape, contour and features of the straight section and transition zone of the aluminum alloy liner part;

[0092] The workpiece is cleaned with an ultrasonic cleaner and dried with a drying device after cleaning.

[0093] Step (4): placing the workpiece obtained in step (3) into a split-type hollow spindle with one end closed. The split-type hollow spindle has two parts connected by bolts. When clamping, the end face of the workpiece boss is in close contact with the inner end face of the hollow spindle. Start the spindle of the spinning machine to rotate the workpiece together with the hollow spindle.

[0094] Use flame heating to preheat the mandrel and the roller, controlling the temperature of the mandrel and the roller at 120-200°C. At the same time, preheat the free end of the workpiece (the part exposed outside the hollow spindle) and control the temperature of the workpiece at 280-350°C.

[0095] Start the preset program of the spinning machine and perform closing spinning. During the closing spinning process, the temperature of the workpiece forming zone is always maintained at 280-350°C. The spinning equipment adopts a commercially available double-wheel CNC spinning machine with a mirror function. The spinning method is a multi-pass closing spinning process in which the double wheels are used alternately. The number of passes is 13. The fillet radii of the wheels are 5mm and 8mm respectively. The spindle speed during spinning is 100r / min. The feed ratio during spinning is 5mm / r, 5mm / r, 5mm / r, 4.5mm / r, 4mm / r, 3.6mm / r, 3.2mm / r, 3mm / r, 2.5mm / r, 2mm / r, 1.5mm / r, 1mm / r, and 1mm / r, respectively, to form an aluminum alloy liner formed part. Stop heating. After the workpiece cools to room temperature, remove the aluminum alloy liner formed part from the hollow spindle.

[0096] The obtained aluminum alloy liner formed part was placed in a box furnace for heating at room temperature. The heating rate was set at 10°C / min and the solution temperature was 575°C. When the furnace temperature reached the preset temperature, the temperature was kept at 45 minutes. After the timer expired, the workpiece was taken out and quenched with water, and the box furnace power was turned off.

[0097] After solution treatment, the workpiece was placed in an aging furnace, the heating rate was set to 10°C / min, and the aging treatment was performed at 180°C for 12 hours. After the aging treatment was completed, the power was turned off, and the workpiece was taken out after cooling to room temperature in the furnace to obtain an aluminum alloy inner liner billet.

[0098] Step (5): Processing of the outer profile of the straight tube section and the elliptical end face: clamping the obtained aluminum alloy inner liner blank on a CNC lathe, and turning the outer diameter of the straight tube section and the outer profile of the elliptical end faces on both sides. At this time, the diameter of the boss is also processed;

[0099] The bottle mouth is processed by using a CNC lathe and special tooling for bottle mouth processing to cut the center hole and external thread of the bottle mouth to obtain the aluminum alloy inner liner parts;

[0100] Use high-pressure water spraying device to clean the aluminum alloy liner parts as a whole, remove the residual aluminum chips, cutting fluid and other pollutants that affect the surface finish (the finished product is shown in the figure below). Figure 4 shown);

[0101] Conduct finished product inspection on the processed aluminum alloy liner parts. Use a calibrated ultrasonic wall thickness gauge to measure the wall thickness of typical points of the aluminum alloy liner parts, and use an outside micrometer to measure the outside diameter of the straight section.

[0102] Use a high-precision balance to weigh the empty weight of the aluminum alloy liner parts, then slowly inject pure water into the liner to the bottle mouth, wait for it to stand, then weigh the full weight, and calculate the volume of the aluminum alloy liner parts;

[0103] Place the inner tank in alcohol for sealing inspection, pass 15MPa air pressure for 5 minutes, and no bubbles are generated.

[0104] The mechanical properties of the obtained product were tested, and the results showed that according to the national standard GB / T 228.1-2021, the yield strength was 330MPa, the tensile strength was 380MPa, and the elongation was 14%; the overall structure of the parts was uniform and dense, and there were no defects caused by heat processing, etc., which is of great significance to the manufacture of high-pressure gas cylinders.

[0105] The foregoing are merely preferred embodiments of the present invention. These embodiments are all different implementations based on the overall concept of the present invention. The scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A precision spinning forming method for aluminum alloy thin-walled seamless liner, characterized in that: The inner liner includes an integrally formed bottle mouth and bottle body. The bottom of the bottle body is provided with a cylindrical boss integrally formed with the bottle body, with a height of 10-25 mm, a diameter of Φ15-30 mm, and a roundness of 0.05 mm. The method: (1) Fix the aluminum alloy sheet on the mandrel of the spinning machine, perform a shear spinning in a heated state, and form an open bowl-shaped part with a certain taper angle. Stop heating, remove the workpiece after cooling, and perform annealing heat treatment; the taper angle is 30°~75°, and the bowl wall thickness is 5~6 times the wall thickness of the straight section of the bottle body; (2) Fixing the workpiece obtained in step (1) on a cylindrical mandrel, performing multiple passes of conventional spinning in a heated state until a straight cup-shaped part with a taper angle of 0 is obtained, stopping heating, removing the workpiece after cooling, and performing annealing heat treatment; the wall thickness of the cup-shaped part is 2 to 3 times the wall thickness of the straight section of the bottle body; (3) Cutting the bottom of the cup-shaped part obtained in step (2) to obtain a workpiece having a boss structure; (4) Fixing the boss end of the workpiece obtained in step (3) on a fixture, performing multiple-pass closing spinning on the open end of the cup-shaped part under heating, stopping heating, removing the workpiece after cooling, and performing solid solution aging heat treatment to obtain an inner liner blank; (5) fine turning the inner liner blank obtained in step (4) to obtain an aluminum alloy inner liner; In step (1), the temperature of the sheet material is between 280°C and 350°C; In step (2), the temperature of the workpiece is controlled at 280-350°C; The number of normal spinning passes in step (2) is 8 to 12; In step (4), the temperature of the workpiece is controlled at 280-350°C; The inner diameter of the bottle mouth is Φ6~8mm.

2. The method according to claim 1, characterized in that The nominal outer diameter of the straight section of the bottle body is Φ90~130mm, the inner liner volume is 0.6~3.0L, the wall thickness of the straight section of the bottle body is 0.7~1.5mm, and the wall thickness of the elliptical end face is 1.2~2.0mm.

3. The method according to claim 1, characterized in that The length of the bottle mouth is 15~35mm, the outside of the bottle mouth is threaded, the thread specification is M12~20, and the roundness of the center hole is 0.02mm.

4. The method according to claim 1, wherein In step (4), the diameter reduction of the closing spinning pass is not greater than the radius of the spinning wheel corner, the solution temperature is 525~575℃, the solution time is 15~45min, the aging temperature is 180~300℃, the aging time is 4~12h, and the heating rates in the solution and aging stages are both 5~20℃ / min.

5. The method according to claim 1, wherein Before the spinning process in steps (1), (2) and (4), the core shaft and the spinning wheel of the spinning machine are preheated to 120-200°C, and the heating method is oxygen / propane flame heating.

6. Application of the aluminum alloy thin-walled seamless liner obtained in claim 1 in the field of aerospace.

7. The method according to any one of claims 1 to 5 is used for forming thin-walled seamless one-piece bottles or cans.

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