Heat treatment shape and property control method for large-length-diameter-ratio thin-wall seamless aluminum alloy lining

Abstract

The invention discloses a shape control and property control method for heat treatment of a large-length-diameter-ratio thin-wall seamless aluminum alloy lining, aiming at the structural characteristics of the large-length-diameter-ratio seamless cylindrical lining, a shape control heat treatment tool is innovatively designed, the deformation of a lining pipe nozzle is effectively controlled, the distortion effect of the lining is eliminated, the profile tolerance of a molded surface of the lining is guaranteed, and the service life of the lining is prolonged. Meanwhile, the lining can be in full contact with a quenching medium through the hollow structure, rapid cooling is achieved, a supersaturated solid solution is formed, and the mechanical property of the lining can be guaranteed; and in combination with the quenching process of step-by-step gradient sinking of the quenching medium, air in the lining can be fully discharged, deformation caused by relative movement between the lining and the tool due to buoyancy of the quenching medium is avoided, and the profile tolerance of the molded surface of the lining is further guaranteed. The overall rapid cooling effect of the lining is guaranteed, and the mechanical property uniformity of different areas of the lining is good.

Description

Technical Field

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

[0002] After the 6061 large aspect ratio thin-walled seamless aluminum alloy lining is formed, it needs to undergo T6 heat treatment to achieve strengthening, that is, solid solution-quenching-artificial aging. The quenching process after solid solution treatment is the key link in controlling the profile and mechanical properties of the aluminum alloy lining during the T6 heat treatment stage. Usually, for large aspect ratio lining components, the following method is used for quenching: the lower end enters the quenching medium vertically, and the upper end is sprayed at the same time. The above-mentioned method for quenching can ensure the formation of a supersaturated solid solution inside the lining material, so that it can disperse and precipitate the strengthening phase in the subsequent artificial aging stage, thereby ensuring the mechanical properties of the lining; however, the difference in cooling rates between the upper and lower ends will cause the lining nozzle to deform, resulting in a "twisting effect", which seriously affects the profile of the lining, resulting in the phenomenon that the local area has reached the lower wall thickness difference in the subsequent mechanical processing stage, while some areas still have a large processing allowance, resulting in the overall lining being out of tolerance and overweight and unable to be used. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to propose a heat treatment shape control and property control method for a thin-walled seamless aluminum alloy lining with a large aspect ratio, to design a heat treatment shape control tooling, to fix the aluminum alloy lining batch in the heat treatment shape control tooling for quenching treatment, to effectively restrain the deformation of the lining nozzle, to eliminate the "twisting effect", to ensure the profile of the lining surface, and at the same time, the mechanical properties of the lining meet the design requirements, and the uniformity in different areas is good.

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

[0005] A method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy liner with a large aspect ratio, wherein the aluminum alloy liner is a columnar structure with nozzles at both ends, and the method comprises:

[0006] Step 1: Prepare a heat treatment control tooling for clamping the aluminum alloy lining for heat treatment;

[0007] Step 2: vertically fix the aluminum alloy lining in the heat treatment shape control tooling to form an assembly;

[0008] Step 3: placing the assembly into a heat treatment furnace for solution treatment. After the treatment is completed, the assembly is taken out of the furnace and sunk into a quenching medium;

[0009] Step 4: After quenching, place the assembly into a heat treatment furnace for aging treatment. After the treatment is completed, remove the aluminum alloy lining from the heat treatment shaping tooling.

[0010] Further, the heat treatment shape-controlling tooling includes an upper grid, a lower grid, a fully threaded tie rod and a nut;

[0011] The upper and lower grids have the same structure, both of which are cylindrical structures with one end open, and hollow grid structures are distributed on the circumferential side walls and bottom surfaces; the open ends of the upper and lower grids are placed opposite to each other up and down, and the two ends of the aluminum alloy lining are fixed to the bottom surfaces of the upper and lower grids respectively;

[0012] A plurality of fully threaded tie rods are connected to the outer edges of the opening ends of the upper grid and the lower grid, and the fully threaded tie rods are fixed by nuts.

[0013] Furthermore, a raised structure is provided on the bottom surface of the upper grid and the lower grid, and the center of the raised structure is located on the center of the bottom circle; the inner diameter and height of the raised structure match the outer diameter and length of the aluminum alloy nozzle, the outer edge has an R structure, the R structure matches the R angle of the nozzle, and the raised structure is mounted on the nozzle.

[0014] Furthermore, a plurality of raised structures are provided on the bottom surfaces of the upper grid and the lower grid, and the center points of the raised structures are evenly distributed on a circle concentric with the bottom surface. Aluminum alloy liners having the same number as the raised structures are placed one by one in each raised structure, thereby achieving simultaneous fixation of multiple aluminum alloy liners.

[0015] Furthermore, the circumferential side walls of the upper and lower grids are layered with hollow grids, which are rectangular and have an outline of 200*55mm; the grid spacing between two adjacent layers is 45-60mm; the bottom surface is provided with multiple rows of hollow grids, which are square and have an outline of 80*80mm, and the spacing between two adjacent grids is 45-60mm.

[0016] Furthermore, the upper end faces of the upper and lower grids have the same number of threaded holes, which are evenly distributed on the outer edges of the upper end faces; the number of threaded holes is the same as the number of full-threaded pull rods, and both ends of the full-threaded pull rods are inserted into the threaded holes of the upper and lower grids and fixed by nuts.

[0017] Further, in step 2, the aluminum alloy lining is vertically fixedly installed in the heat treatment shape control tooling, and the specific method is as follows:

[0018] The nozzle at the lower end of the aluminum alloy liner is installed into the raised structure of the lower grid, and all the fully threaded tie rods are installed one by one in the threaded holes on the upper end surface of the lower grid, and tightened one by one with nuts; another nut is taken and fixed one by one in the middle position of each fully threaded tie rod;

[0019] Place the upper grid upside down on the aluminum alloy lining so that the nozzle at the upper end of the lining is inserted into the raised structure of the upper grid, and then rotate the upper grid until the threaded holes on the upper end surface of the upper grid contact the free ends of each fully threaded tie rod one by one; rotate each fully threaded tie rod in the opposite direction so that the free ends of the fully threaded tie rods are fixed in the corresponding threaded holes of the upper grid, and press the nuts in the middle position of the fully threaded tie rods one by one to the corresponding positions on the upper end surface of the upper grid.

[0020] Further, in step three, the assembly is sunk into the quenching medium, and the sinking method is: one-third of the height direction of the aluminum alloy lining in the assembly is completely in contact with the quenching medium, and paused for 3 seconds; then continue to sink into one-third of the height of the aluminum alloy lining, and also pause for 3 seconds; finally, the remaining aluminum alloy lining is completely sunk into the quenching medium until it is completely cooled.

[0021] Furthermore, in step three, the quenching transfer time of the assembly does not exceed 12 seconds.

[0022] Furthermore, the material of the heat treatment shape-controlling tooling is 16Mn structural steel.

[0023] The advantages of the present invention compared with the prior art are:

[0024] (1) In view of the structural characteristics of the seamless cylindrical lining with a large aspect ratio, the present invention innovatively designs a heat treatment shape-controlling tooling of "symmetrical hollow grid + tie rod-nut + local constraint structure", which effectively controls the deformation of the lining nozzle, eliminates the "twisting effect" of the lining, and ensures the surface contour of the lining. At the same time, the hollow structure allows the lining to fully contact with the quenching medium, achieving rapid cooling and forming a supersaturated solid solution, which helps to ensure the mechanical properties of the lining.

[0025] (2) The present invention adopts a quenching process of step-by-step gradient sinking into the quenching medium, so that the air in the liner can be fully discharged, avoiding deformation caused by relative movement between the liner and the tooling due to the buoyancy of the quenching medium, which helps to ensure the surface contour of the liner.

[0026] (3) The quenching transfer time of the present invention does not exceed 12 seconds, which ensures the rapid cooling effect of the entire lining and makes the mechanical properties of different areas of the lining uniform.

[0027] (4) The present invention can realize T6 heat treatment of multiple lining batches, greatly improving production efficiency.

[0028] (5) The heat treatment shape control and property control method of the present invention for a thin-walled seamless aluminum alloy lining with a large aspect ratio is simple in process, easy to implement, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Various other advantages and benefits will become apparent to those skilled in the art by reading the following detailed description of the preferred embodiments.

[0030] Figure 1 This is a schematic diagram of the structure after the heat treatment shape control tooling and the lining are assembled according to an embodiment of the present invention;

[0031] Figure 2 It is a partial cross-sectional enlarged view of the heat treatment shape control tooling and the liner after being assembled according to an embodiment of the present invention;

[0032] Figure 3 It is a schematic diagram of the partial structure after the heat treatment shape control tooling and the lining are assembled according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] 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.

[0034] The present invention proposes a heat treatment shape control and property control method for a thin-walled seamless aluminum alloy lining with a large aspect ratio, comprising the following steps:

[0035] Step 1: Prepare a liner heat treatment shape control tooling, which can simultaneously clamp 4 liners 3 for heat treatment.

[0036] Lining heat treatment control tooling such as Figure 1 As shown, it includes an upper grid 2, a lower grid 1, a full-thread tie rod 4, and a nut 5, which are 1, 1, 8, and 16 in number, respectively, and are all made of 16Mn structural steel. The nut 5 matches the full-thread tie rod 4.

[0037] The upper grid 2 and the lower grid 1 are symmetrically designed, with a height of 500-600mm, an outer diameter of 2400-2600mm, and a thickness of 25mm. The designed size is based on the ability to envelop all the liners 3 to be loaded. The upper grid 2 and the lower grid 1 are distributed with hollow grid structures in the circumference and bottom, where the circumferential grid is rectangular with an outline of 200*55mm, distributed in 6 height bands, and each height band is evenly distributed with 24 grids; the grid spacing between two adjacent height bands is 45-60mm. The bottom grid is square with an outline of 80*80mm, and the spacing between two adjacent grids is 45-60mm. The design of the hollow grid structure allows the lining to fully contact with the quenching medium, achieve rapid cooling, and form a supersaturated solid solution, which helps to ensure the mechanical properties of the lining. At the same time, the upper grid 2 and the lower grid 1 with hollow grids must meet the quenching requirements and will not be unable to completely sink into the quenching medium due to excessive buoyancy.

[0038] There are 4 local constraints 6 at the bottom of the upper grid 2 and the lower grid 1, such as Figure 2 As shown, the centers of the four local constraints 6 are evenly distributed on a circle with a diameter of 1400-1500mm, and the circle with a diameter of 1400-1500mm is concentric with the bottom. The four local constraints 6 are convex structures, whose inner diameter and height match the outer diameter and length of the liner 3 nozzle, and the thickness of the convex structure is 5-10mm; the outer edge of the convex structure has an R structure, which matches the R angle of the liner 3 nozzle. The design of the local constraint 6 effectively controls the deformation of the liner nozzle, eliminates the "twisting effect" of the liner, and ensures the profile of the liner.

[0039] The upper end surfaces of the upper grid 2 and the lower grid 1 are each provided with 8 threaded holes 7, such as Figure 3 As shown, and are evenly distributed on the upper end surface, with a depth of 60-80mm.

[0040] The assembly method of this tool is as follows: 8 fully threaded tie rods 4 are installed one by one in the threaded holes 7 on the upper end surface of the lower grid 1, and the tie rods 4 are in contact with the bottom ends of the threaded holes 7; after the upper grid 2 is inverted on the lining 3 and the threaded holes 7 on the upper end surface of the upper grid 2 are in the position of the 8 tie rods 4, the 8 tie rods 4 are rotated in the opposite direction, and the reverse displacement of the tie rods 4 is half the depth of the threaded holes 7, so that the free ends are fixed in the corresponding threaded holes 7 of the upper grid 2. The 16 nuts 5 are tightly matched with the upper end surfaces of the upper grid 2 and the lower grid 1.

[0041] Step 2: vertically fix 4 cylindrical aluminum alloy liners 3 with small nozzles at both ends on the lower grid 1 of the heat treatment control tooling one by one, and the nozzle at the lower end of the liner 3 is tightly matched with the local constraint 6 of the lower grid 1; install 8 full-thread tie rods 4 one by one in the threaded holes 7 on the upper end surface of the lower grid 1, and use 8 matching nuts 5 to tighten them one by one; take another 8 matching nuts 5 and fix them one by one in the middle position of the 8 full-thread tie rods 4; turn the upper grid 2 upside down on the liner 3, so that the nozzle at the upper end of the liner 3 is tightly matched with the local constraint 6 of the upper grid 2, and then rotate the upper grid 2 until the threaded hole 7 on the upper end surface of the upper grid 2 is in the position of the 8 tie rods 4; rotate the 8 tie rods 4 in opposite directions respectively, so that their free ends are fixed in the corresponding threaded holes 7 of the upper grid 2, and press the 8 nuts 5 in the middle position of the full-thread tie rods 4 to the corresponding positions on the upper end surface of the upper grid 2 one by one.

[0042] Step 3: Place the aluminum alloy lining 3 vertically mounted on the heat treatment control tooling into the heat treatment furnace for solution treatment. After the treatment is completed, quickly remove the heat treatment tooling and the columnar aluminum alloy lining 3 from the furnace and sink them into the quenching medium. The quenching transfer time does not exceed 12 seconds. The quenching process is: after one-third of the height direction of the lining 3 is completely in contact with the quenching medium, pause for 3 seconds; then continue to sink one-third, and also pause for 3 seconds; finally, completely sink the remaining one-third into the quenching medium until it is completely cooled.

[0043] Step 4: After quenching, the shape-controlling heat treatment tooling and the columnar aluminum alloy liner 3 are placed together in a heat treatment furnace for aging treatment. After the aging treatment is completed, the aluminum alloy liner is removed from the heat treatment shape-controlling tooling.

[0044] Example 1

[0045] In this embodiment, the 6061 aluminum alloy liner is formed by spinning the ends of the aluminum alloy pipe to form a hollow liner with a small nozzle and an ellipsoidal head at both ends and a cylindrical straight section between them. The volume is 130L, the total length is 1300mm, the inner diameter is Ф400mm, the wall thickness is 7.6mm, the straight section is 870mm, the straightness of the straight section is <0.5mm, the outer diameter of the nozzle is Ф56mm, and the inner diameter is Ф20mm. The specific process of the heat treatment method is as follows:

[0046] Step (i), fix four 6061 aluminum alloy columnar liners 3 on the heat treatment shape control tooling;

[0047] Step (ii), placing the four large-volume liners 3 installed on the heat treatment tooling into the heat treatment furnace for solution treatment, keeping the temperature at 500±5°C for 60 minutes, and after the treatment, quickly taking the heat treatment tooling and the columnar aluminum alloy liners 3 out of the furnace, and then step by step gradient completely sinking them into the quenching medium, and the entire quenching transfer time does not exceed 12 seconds;

[0048] Step (iii), after quenching, the processing tool and the columnar aluminum alloy liner 3 are placed in a heat treatment furnace for aging treatment, kept at 165±5°C for 10 hours, and air-cooled. After the treatment is completed, the aluminum alloy liner 3 is removed from the heat treatment control tool.

[0049] Table 1 Mechanical properties of 130L aluminum alloy inner liner

[0050]

[0051] The mechanical properties of the treated liner 3 bottle body in this embodiment are shown in Table 1. The mechanical properties of the upper and lower nozzles and the nearby straight sections meet the design requirements. The straightness of the liner straight section is <0.5mm, which meets the design requirement of ≤1.0mm, ensuring the mechanical properties and dimensional accuracy of the product and improving the reliability of the liner.

[0052] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0053] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy liner with a large aspect ratio, wherein the aluminum alloy liner is a cylindrical structure with nozzles at both ends, characterized in that the method include: Step 1: Prepare a heat treatment control tooling for clamping the aluminum alloy lining for heat treatment; Step 2: vertically fix the aluminum alloy lining in the heat treatment shape control tooling to form an assembly; Step 3: placing the assembly into a heat treatment furnace for solution treatment. After the treatment is completed, the assembly is taken out of the furnace and sunk into a quenching medium; Step 4: After quenching, place the assembly into a heat treatment furnace for aging treatment. After the treatment is completed, remove the aluminum alloy lining from the heat treatment shaping tooling.

2. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 1, characterized in that: The heat treatment shape control tooling includes an upper grid, a lower grid, a fully threaded tie rod and a nut; The upper and lower grids have the same structure, both of which are cylindrical structures with one end open, and hollow grid structures are distributed on the circumferential side walls and bottom surfaces; the open ends of the upper and lower grids are placed opposite to each other up and down, and the two ends of the aluminum alloy lining are fixed to the bottom surfaces of the upper and lower grids respectively; A plurality of fully threaded tie rods are connected to the outer edges of the opening ends of the upper grid and the lower grid, and the fully threaded tie rods are fixed by nuts.

3. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 2, characterized in that: A raised structure is provided on the bottom surface of the upper grid and the lower grid, and the center of the raised structure is located on the center of the bottom circle; the inner diameter and height of the raised structure match the outer diameter and length of the aluminum alloy nozzle, the outer edge has an R structure, the R structure matches the R angle of the nozzle, and the raised structure is mounted on the nozzle.

4. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 3, characterized in that: A plurality of raised structures are arranged on the bottom surfaces of the upper and lower grids, and the center points of the raised structures are evenly distributed on a circle concentric with the bottom surface. Aluminum alloy liners having the same number as the raised structures are placed in each raised structure one by one, thereby achieving simultaneous fixation of multiple aluminum alloy liners.

5. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 2, characterized in that: The circumferential side walls of the upper and lower grids are layered with hollow grids, which are rectangular with an outline of 200*55mm; the grid spacing between two adjacent layers is 45-60mm; the bottom surface is provided with multiple rows of hollow grids, which are square with an outline of 80*80mm, and the spacing between two adjacent grids is 45-60mm.

6. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 2, characterized in that: The upper end faces of the upper and lower grids have the same number of threaded holes, which are evenly distributed on the outer edges of the upper end faces; the number of threaded holes is the same as the number of full-threaded tie rods, and both ends of the full-threaded tie rods are inserted into the threaded holes of the upper and lower grids and fixed by nuts.

7. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 2, characterized in that: In step 2, the aluminum alloy lining is vertically fixed and installed in the heat treatment shape control tooling. The specific method is as follows: The nozzle at the lower end of the aluminum alloy liner is installed into the raised structure of the lower grid, and all the fully threaded tie rods are installed one by one in the threaded holes on the upper end surface of the lower grid, and tightened one by one with nuts; another nut is taken and fixed one by one in the middle position of each fully threaded tie rod; Place the upper grid upside down on the aluminum alloy lining so that the nozzle at the upper end of the lining is inserted into the raised structure of the upper grid, and then rotate the upper grid until the threaded holes on the upper end surface of the upper grid contact the free ends of each fully threaded tie rod one by one; rotate each fully threaded tie rod in the opposite direction so that the free ends of the fully threaded tie rods are fixed in the corresponding threaded holes of the upper grid, and press the nuts in the middle position of the fully threaded tie rods one by one to the corresponding positions on the upper end surface of the upper grid.

8. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 1, characterized in that: In step three, the assembly is sunk into the quenching medium in the following manner: one third of the height of the aluminum alloy lining in the assembly is completely in contact with the quenching medium and paused for 3 seconds; then, the assembly is sunk into one third of the height of the aluminum alloy lining and paused for 3 seconds; finally, the remaining aluminum alloy lining is completely sunk into the quenching medium until it is completely cooled.

9. The method for heat treatment shape control and property control of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 1, characterized in that: In step 3, the quenching transfer time from when the assembly is taken out of the furnace to when it contacts the quenching medium is no more than 12 seconds.

10. The heat treatment shape control and property control method of a thin-walled seamless aluminum alloy lining with a large aspect ratio according to claim 1, characterized in that: The material of the heat treatment shape control tooling is 16Mn structural steel.

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