A manufacturing apparatus and method for large aluminum alloy thin-walled hemispherical parts

Abstract

This invention discloses a manufacturing apparatus and method for large aluminum alloy thin-walled hemispherical parts, relating to the technical field of machining. The invention aims to solve the problems of complex processes and low efficiency in the production of large aluminum alloy thin-walled hemispherical parts. The invention includes a press, comprising a lower worktable, a crossbeam mounted on the top of the lower worktable via a column, an upper worktable mounted on the outer wall of the column via a guide sleeve, a hydraulic cylinder mounted in the middle of the top of the crossbeam, and the hydraulic cylinder connected to the upper worktable via a piston rod. A drawing punch is connected to the upper worktable via a connecting flange, and a drawing die is mounted in the middle of the top of the lower worktable. The parts are formed by hot drawing using the press, and then machined to the required dimensions using a CNC vertical lathe. All equipment used is general-purpose production equipment, resulting in low equipment costs. Through process optimization, the product qualification rate and production efficiency are improved, and manufacturing costs are reduced.

Description

Technical Field

[0001] This invention relates to the field of machining technology, specifically to a manufacturing apparatus and method for large aluminum alloy thin-walled hemispherical parts. Background Technology

[0002] Large aluminum alloy thin-walled hemispheres are commonly used in the manufacture of fuel tanks for aviation and aerospace industries. Their structural characteristics include large size, light weight, thin walls, and high dimensional accuracy. The typical manufacturing methods for hemispherical parts involve high-pressure spinning, forging, casting, superplastic forming, or explosive forming, followed by machining to the required dimensions using large CNC five-axis machining centers and other precision equipment. This process requires specialized equipment, which is scarce, expensive, complex, costly, inefficient, and has a relatively low yield rate. Summary of the Invention

[0003] To address the aforementioned problems, specifically those raised in the background section, this invention provides a manufacturing apparatus and method for large aluminum alloy thin-walled hemispherical parts. The apparatus includes a press, comprising a lower worktable. A crossbeam is mounted on the top of the lower worktable via a column. An upper worktable is mounted on the outer wall of the column via a guide sleeve. A hydraulic cylinder is mounted in the center of the top of the crossbeam. The hydraulic cylinder is connected to the upper worktable via a piston rod. A drawing punch is connected to the upper worktable via a connecting flange. A drawing die is mounted in the center of the top of the lower worktable.

[0004] A further configuration of the present invention is that the drawing punch is located directly above the drawing die.

[0005] A further provision of the present invention is that the deformation size of the drawing punch and drawing die per pass ranges from 20% to 30%.

[0006] A further provision of the present invention includes the following manufacturing method:

[0007] S1. Fix the drawing punch on the upper worktable and the drawing die on the lower worktable, and cut the blank according to the part drawing;

[0008] S2. Place the part blank in a heat treatment furnace and heat it evenly to 370℃;

[0009] S3. Position the heated and heat-preserved part blank in the deep drawing die, start the press, and the upper worktable drives the deep drawing punch to slowly press the part blank into the deep drawing die to complete one pre-drawing forming.

[0010] S4. Place the pre-drawn part blank in a heat treatment furnace and heat it evenly to 175°C. After holding it at that temperature for 8 hours, anneal it to relieve stress.

[0011] S5. Replace the drawing punch and drawing die of different sizes, and repeat S2-S4 for four to six passes to perform hot drawing and shape correction.

[0012] S6. The shaped part blank is subjected to solution treatment, heated to 510℃-540℃, held at the temperature for 2 hours and then rapidly cooled to room temperature.

[0013] S7. After solution treatment, the part blank is subjected to aging treatment. The temperature is heated to 120℃-140℃ and held for 16-20 hours.

[0014] S8. Perform CNC rough turning on the aged part blank, leaving a 1mm finishing allowance on both the inner and outer surfaces of the part blank.

[0015] S9. Perform CNC finish turning on the part blank after CNC rough turning.

[0016] The beneficial technical effects of the present invention are as follows: The present invention provides a manufacturing device and method for large aluminum alloy thin-walled hemispherical parts, which are formed by hot deep drawing process of press and then machined by CNC vertical lathe to meet the dimensional requirements. All the equipment used are general production equipment, and the equipment cost is low. Through process optimization, the product qualification rate and production efficiency are improved, and the manufacturing cost is reduced.

[0017] The hemispherical part forming process employs a multi-pass hot drawing and shaping process. By optimizing the forming process, a general-purpose press is selected for deep drawing and shaping, reducing equipment operating costs. Machining utilizes a CNC vertical lathe with specialized tooling fixtures. During finishing, a vacuum adsorption clamping method is used, allowing the thin-walled hemispherical part to be tightly bonded to the high-precision fixture surface by atmospheric pressure. This solves the problems of thin walls, poor rigidity, easy deformation, and difficulty in ensuring machining accuracy in hemispherical parts. Since mechanical clamping devices such as pressure plates are not required, the hemispherical part can be machined in one pass, avoiding machining errors caused by secondary clamping. Replacing the few and expensive specialized high-precision equipment with a general-purpose press and CNC vertical lathe saves processing costs and improves production capacity and efficiency. Attached Figure Description

[0018] Figure 1 A schematic diagram of the deep drawing device is shown.

[0019] Reference numerals: 1. Crossbeam, 2. Upper worktable, 3. Lower worktable, 4. Drawing punch, 5. Drawing die, 6. Column, 7. Hydraulic cylinder, 8. Piston rod. Detailed Implementation

[0020] The following is a reference to the appendix. Figure 1The preferred embodiments of the present invention will be described below. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0021] This invention proposes a manufacturing apparatus and method for large aluminum alloy thin-walled hemispherical parts, including a press. The press includes a lower worktable 3, with a crossbeam 1 mounted on the top of the lower worktable 3 via a column 6. An upper worktable 2 is mounted on the outer wall of the column 6 via a guide sleeve, allowing the upper worktable 2 to slide on the outer wall of the column 6. A hydraulic cylinder 7 is mounted in the middle of the top of the crossbeam 1, and the hydraulic cylinder 7 is connected to the upper worktable 2 via a piston rod 8. A drawing punch 4 is connected to the upper worktable 2 via a connecting flange. A drawing die 5 is mounted in the middle of the top of the lower worktable 3. The drawing punch 4 is located directly above the drawing die 5. The drawing punch 4 and the drawing die 5 are detachable and replaceable with different sizes, and the deformation range of the drawing punch 4 and the drawing die 5 per pass is 20%-30%.

[0022] Including the following manufacturing methods:

[0023] S1. Fix the drawing punch 4 on the upper worktable 2 and the drawing die 5 on the lower worktable 3, and cut the blank according to the part drawing.

[0024] S2. Place the part blank in a heat treatment furnace and heat it evenly to 370℃. The commonly used material for hemispheres in the aerospace field is 2219 hard aluminum alloy, which has excellent properties such as low density, corrosion resistance, heat treatment, good weldability, and high fracture toughness. The part blank has an elongation after fracture of 53% and a yield strength of 30 MPa at 370℃, which is the best state for forming performance.

[0025] S3. Position the heated and kept-warm part blank in the deep drawing die 5. Start the press, and the upper worktable 2 drives the deep drawing punch 4 to slowly press the part blank into the deep drawing die 5, completing one pre-drawing forming. The die adopts a pressure ring structure, with multiple sets of dies combined for multiple hot drawing passes, and annealing treatment is performed between passes. Based on the material's deep drawing performance, and calculating with a deformation of 25%-30% per hot drawing pass, four passes of hot drawing are used. To ensure the accuracy after forming, the part is straightened and shaped after deep drawing, and then subjected to solution aging treatment to improve the strength and hardness of the part material.

[0026] S4. The pre-drawn part blank is placed in a heat treatment furnace and uniformly heated to 175°C. After holding at this temperature for 8 hours, it is annealed to relieve stress. Annealing is mainly to eliminate stress in the hemispherical part and reduce its deformation. The material has a high strength, with an elongation of 15% and a yield strength of 75 MPa after annealing to room temperature.

[0027] S5. Replace the drawing punch 4 and drawing die 5 with different sizes, and repeat S2-S4 for four to six passes of hot drawing and shaping; according to the actual situation of the part blank, complete the drawing and shaping of different passes, and the dimensional requirements can be met after four to six passes of hot drawing.

[0028] S6. The shaped part blank is subjected to solution treatment. The temperature is heated to 510℃-540℃, held at the temperature for 2 hours, and then rapidly cooled to room temperature. Solution treatment can improve its mechanical properties and dimensional stability.

[0029] S7. After solution treatment, the part blank is subjected to aging treatment at 120℃-140℃ for 16-20 hours. The elongation at break after solution treatment at room temperature is 20%, and the yield strength is 185 MPa, significantly improving overall performance and meeting product strength requirements. The hemispherical part is then reheated to a lower temperature to allow the internal solid solution to precipitate again, forming certain strengthening components. Aging treatment can significantly improve the strength and hardness of aluminum alloys.

[0030] S8. Perform CNC rough turning on the aged part blank, leaving a 1mm finishing allowance on both the inner and outer surfaces of the part blank.

[0031] S9. Perform CNC finish turning on the part blank after CNC rough turning.

[0032] Because these thin-walled hemispherical parts, with large diameters and varying wall thicknesses (the thinnest part being only about 1mm), require high dimensional accuracy, have poor rigidity, and are prone to deformation, the final dimensional accuracy must be ensured through machining. Based on the characteristics of the part, a CNC vertical lathe machining scheme was adopted. Using specialized tooling and fixtures, multiple roughing and finishing operations were performed to finally achieve the required product dimensions. After roughing, the wall thickness of the hemisphere becomes thinner, resulting in poor overall rigidity. During clamping, the part and fixture must fit tightly. To ensure a stable fit of the thin-walled hemisphere on the fixture and smooth demolding after machining, a vacuum adsorption clamping method was adopted.

[0033] The hemispherical part is clamped on the punch of the hemispherical rough turning fixture, and the outer surface of the hemispherical part is rough turned, leaving a 1mm finishing allowance. The rough-machined hemispherical part is clamped on the die of the hemispherical rough turning fixture, and the inner surface of the hemispherical part is rough turned, leaving a 1mm finishing allowance. The rough-machined hemispherical part is clamped on the die of the hemispherical finish turning fixture by vacuum adsorption, and the inner surface of the hemispherical part is finish turned on a CNC vertical lathe to meet the dimensional requirements. The hemispherical part is clamped on the punch of the hemispherical finish turning fixture by vacuum adsorption, and the outer surface of the hemispherical part is finish turned to meet the dimensional requirements. Finally, a hemispherical part with a wall thickness to inner diameter radius of curvature ratio of less than 1:1000 can be obtained.

[0034] Appendix: The vacuum adsorption fixture mentioned in this article refers to a turning fixture for large thin-walled hemispherical parts with application number CN201821595524.X.

[0035] Although the invention has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0036] In the description of this invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate direction or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those processes, articles, or apparatus / devices.

[0039] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing large aluminum alloy thin-walled hemispherical parts, comprising a press, characterized in that: The press includes a lower worktable (3), a crossbeam (1) is installed on the top of the lower worktable (3) via a column (6), an upper worktable (2) is installed on the outer wall of the column (6) via a guide sleeve, a hydraulic cylinder (7) is installed in the middle of the top of the crossbeam (1), the hydraulic cylinder (7) is connected to the upper worktable (2) via a piston rod (8), a drawing punch (4) is connected to the upper worktable (2) via a connecting flange, a drawing die (5) is installed in the middle of the top of the lower worktable (3), the drawing punch (4) is located directly above the drawing die (5), and the deformation size of the drawing punch (4) and the drawing die (5) per pass is 20%-30%; Including the following manufacturing methods: S1. Fix the drawing punch (4) on the upper worktable (2) and the drawing die (5) on the lower worktable (3). Cut the blank according to the part drawing. S2. Place the part blank in a heat treatment furnace and heat it evenly to 370℃; S3. Position the heated and heat-preserving part blank in the deep drawing die (5), start the press, and the upper worktable (2) drives the deep drawing punch (4) to slowly press the part blank to the deep drawing die (5) to complete one pre-drawing forming. S4. Place the pre-drawn part blank in a heat treatment furnace and heat it evenly to 175°C. After holding it at that temperature for 8 hours, anneal it to relieve stress. S5. Replace the drawing punch (4) and drawing die (5) of different sizes, and repeat S2-S4 for four to six passes to perform hot drawing and shape correction. S6. The shaped part blank is subjected to solution treatment, heated to 510℃-540℃, held at the temperature for 2 hours and then rapidly cooled to room temperature. S7. After solution treatment, the part blank is subjected to aging treatment. The temperature is heated to 120℃-140℃ and held for 16-20 hours. S8. Perform CNC rough turning on the aged part blank, leaving a 1mm finishing allowance on both the inner and outer surfaces of the part blank. S9. Perform CNC finish turning on the part blank after CNC rough turning.

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