Method and apparatus for forming a variable diameter aluminum alloy tube

Abstract

The present application relates to a kind of reducing aluminum alloy pipe forming method and its device, belong to metal material forming technical field, solve the machining allowance of prior art inner hole, machining pass is more, production cycle is long, manufacturing cost is high;Inner hole deformation streamline is cut off, and performance is influenced.The present application proposes a kind of special near-net forming reducing pipe device.With the aid of the device, a kind of near-net forming reducing pipe method is proposed, not only can near isothermal backward extrusion forming reducing aluminum alloy pipe, but also can be accurately controlled deformation temperature and deformation, near-net forming reducing pipe.Not only can reduce the machining allowance of inner hole, shorten processing cycle, but also can reduce the deformation streamline cut-off of inner hole, improve the comprehensive performance of pipe.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal material forming, in particular to a variable-diameter aluminum alloy pipe forming method and device. BACKGROUND

[0002] In the field of aerospace, ship, etc., the shell of equipment develops towards large size, high performance and low cost, and the requirements for the variable-diameter aluminum alloy pipe for the shell are also higher and higher. In order to meet the use requirements of the shell, the common method is to first prepare an equal-wall-thickness pipe, and then process the equal-wall-thickness pipe into a shell part with a variable-diameter inner hole according to a part drawing. However, this method has two problems, on the one hand, the machining allowance of the inner hole is large, the machining passes are many, the production cycle is long, and the manufacturing cost is high; on the other hand, the deformation streamline of the inner hole is cut off, and the performance is affected.

[0003] In order to solve the above problems, a near-net forming variable-diameter pipe can be considered, which can not only reduce the machining allowance of the inner hole, shorten the processing cycle, but also reduce the deformation streamline cut-off of the inner hole, and improve the comprehensive performance of the shell. How to near-net form the variable-diameter pipe has become an urgent problem to be solved. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a variable-diameter aluminum alloy pipe forming method and device to at least solve one of the following problems: (1) there are still many problems to be solved in how to near-net form the variable-diameter pipe in the prior art; (2) the machining allowance of the inner hole is large, the machining passes are many, the production cycle is long, and the manufacturing cost is high in the prior art; (3) the deformation streamline of the inner hole is cut off, and the performance of the pipe is affected in the prior art.

[0005] In one aspect, the embodiments of the present application provide a variable-diameter aluminum alloy pipe forming device, which comprises an extrusion rod, an extrusion punch, a heating and heat preservation device, a concave die, a lower ejector rod and a lower punch;

[0006] The extrusion punch is fixed at the lower end of the extrusion rod, and the extrusion of the extrusion punch on the ingot is realized by the movement of the extrusion rod; the concave die is fixed on the base of the forming device and is fixed relative to the base to form a closed forming cavity to provide a forming space for the ingot; the inner cavity shape of the forming cavity matches the cross-sectional shape of the aluminum alloy pipe to be formed; the heating and heat preservation device surrounds the concave die for temperature control; the lower ejector rod is movably inserted into the hole provided in the center of the base for supporting the ingot during the forming process and ejecting the finished product from the concave die after the forming is completed; the lower punch is fixed on the upper surface of the base in the forming cavity, the lower punch is provided with a lower ejector rod through hole, and the lower ejector rod is in sealing connection with the lower ejector rod through hole.

[0007] Further, the variable-diameter aluminum alloy pipe is a three-section wall thickness pipe or a two-section wall thickness pipe; the outer diameter of the variable-diameter aluminum alloy pipe is consistent,

[0008] the inner diameter of the concave die 凹模 = d 外径 , wherein d 外径 is the outer diameter of the variable-diameter aluminum alloy pipe;

[0009] The variable-diameter aluminum alloy pipe is a three-section wall thickness pipe, and the wall thicknesses of the pipe from top to bottom are B1, B3 and B2 in sequence, the height of the lower punch is l2, the height of the lower ejector rod on the base is l2+l3-h, the diameter of the extrusion punch is D1=d 凹模 -2×B1, the diameter of the lower punch is D2=d 凹模 -2×B2, and the diameter of the lower ejector rod is D3=d 凹模 -2×B3.

[0010] wherein h is the forming allowance, l2 and l3 are the pipe lengths corresponding to the wall thicknesses B2 and B3 respectively.

[0011] Further, the variable-diameter aluminum alloy pipe is a two-section wall thickness pipe, and the wall thicknesses of the pipe from top to bottom are B1 and B2 in sequence, the height of the lower punch and the height of the lower ejector rod on the base are consistent, both being l2-h, the diameter of the extrusion punch is D1=d 凹模 -2×B1, the diameter of the lower punch is D2=d 凹模 -2×B2, and the diameter of the lower ejector rod is D3<D2.

[0012] wherein h is the forming allowance, d 凹模 is the inner diameter of the concave die, and l2 is the pipe length corresponding to the wall thickness B2.

[0013] Further, the bottom surface of the extrusion punch is tapered at an angle α 冲头 = 1°-5°, and the round corner is R 冲头 = R3-R8; the wall surface of the concave die is tapered at an angle α 凹模 = 0.5°-1°.

[0014] In another aspect, the embodiment of the present application provides a variable-diameter aluminum alloy pipe forming method, which uses the forming device described above, and includes the following steps:

[0015] S1, setting the forming device according to the wall thickness of the target variable-diameter pipe;

[0016] S2, heating the aluminum alloy ingot and the forming device respectively;

[0017] S3, using the set forming device to perform near-net forming of the variable-diameter pipe through near-isothermal backward extrusion.

[0018] Further, in S1, the target variable-diameter pipe material is a two-section wall thickness pipe material, the height of the lower punch and the height of the lower ejector rod on the base are consistent.

[0019] Further, in S1, the target variable-diameter pipe material is a three-section wall thickness pipe material, the pipe wall thicknesses from top to bottom are B1, B3 and B2, the height of the lower punch is less than the height of the lower ejector rod on the base, and the diameter D3 of the lower ejector rod is equal to d 凹模 -2xB3, wherein d 凹模 is the concave die forming inner diameter.

[0020] Further, in S2, the heating temperature T 装置 is T 锭坯 ±20℃.

[0021] Further, in S3, the near-net forming variable-diameter pipe material formed by the near-isothermal backward extrusion has a forming speed S of 2-6 mm / s, and the forming pressure excess is not less than 15 mm.

[0022] Further, S3 includes:

[0023] S301. Placing the heated ingot into the concave die forming cavity in the heated forming device;

[0024] S302. Opening the hydraulic machine connected to the extrusion rod, pushing the extrusion rod to drive the extrusion punch downward to apply pressure to the ingot, and the ingot first flows to the space between the concave die and the lower punch and the lower ejector rod, and then flows along the inner wall of the concave die to the opening end of the concave die;

[0025] S303. Closing the hydraulic machine, stopping the movement of the extrusion punch, and completing the forming process;

[0026] S304. Changing the pressure direction of the hydraulic machine to push the lower ejector rod to move upward to eject the formed metal piece from the concave die.

[0027] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0028] 1) Although the near-net forming variable-diameter pipe material has been studied, the method has very high requirements for the forming device and the material, and it is still difficult to find a suitable and exact near-net forming variable-diameter pipe material method. The present application proposes a special near-net forming variable-diameter pipe material device, which can be used for near-isothermal backward extrusion forming variable-diameter aluminum alloy pipe material of aluminum-based composite materials, magnesium alloy and other difficult forming materials, and can also accurately control the deformation temperature and deformation amount to near-net form the variable-diameter pipe material and improve the comprehensive performance of the pipe material.

[0029] 2) The existing method for forming variable-diameter aluminum alloy pipes has a large machining allowance for the inner hole, multiple machining passes, a long production cycle, and high manufacturing cost. The present application proposes a method for near-net forming variable-diameter pipes, which can precisely adjust the inner hole and wall thickness of the pipe during the forming process by setting the diameters of the corresponding tools of the device, to meet the design requirements, thereby helping to reduce the machining allowance at the inner hole, reduce the machining passes and production cycle, and reduce the manufacturing cost. The material utilization rate can be increased from the traditional 10% to 20% to more than 50%, reducing material waste.

[0030] 3) The existing method for forming variable-diameter aluminum alloy pipes has deformation flow lines cut off at the inner hole, affecting the performance of the pipe. The present application is a gentle forming of the material, which can reduce the damage and stress concentration of the material. By precisely controlling the deformation and stress distribution during the forming process, near-net forming of the pipe is achieved, thereby reducing the cut-off of the deformation flow lines at the inner hole and improving the overall performance of the pipe.

[0031] The above technical solutions in the present application can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood by implementing the present application. The purpose and other advantages of the present application can be achieved and obtained from the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0033] Figure 1 Figure 1 is a schematic diagram of the variable-diameter aluminum alloy pipe forming device of the present application;

[0034] Figure 2 Figure 2 is a schematic diagram of the key dimensions of the lower punch of the present application; Figure 1

[0035] Figure 3 is a schematic diagram of the key dimensions of the extrusion punch of the present application; Figure 3 Figure 1 Figure 4 is a schematic diagram of the variable-diameter pipe of the present application;

[0036] Figure 4 Figure 1 Figure 5 is a schematic diagram of the machining of the equal-wall-thickness pipe into the variable-diameter pipe of the present application;

[0037] Figure 5

[0038] Figure 6 ​​​A comparison chart of the flow lines of the equal-wall-thickness pipe machined into the variable-diameter pipe and the flow lines of the variable-diameter pipe of the present application.

[0039] Reference signs:

[0040] 1 - extrusion rod; 2 - extrusion punch; 3 - heating and insulation device; 4 - concave die; 5 - lower ejection rod; 6 - ingot blank; 7 - lower punch; 8 - acting force; 9 - crack; 10 - base. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application, and together with the embodiments of the present application serve to explain the principles of the present application, and are not intended to limit the scope of the present application.

[0042] One specific embodiment of the present application discloses a variable-diameter aluminum alloy pipe forming device, which can near-net shape the variable-diameter pipe, and the specific structure is as shown in Figure 1 which comprises an extrusion rod, an extrusion punch, a heating and insulation device, a concave die, a lower ejection rod and a lower punch.

[0043] The extrusion punch is fixed at the lower end of the extrusion rod, and the extrusion of the extrusion punch on the ingot blank is realized by the movement of the extrusion rod; the concave die is fixed on the base of the forming device and is fixed relative to the base to form a closed forming cavity to provide forming space for the ingot blank; the inner cavity shape of the forming cavity matches the cross-sectional shape of the aluminum alloy pipe to be formed; the heating and insulation device surrounds the concave die to control the temperature; the lower ejection rod is movably inserted into the hole provided in the center of the base, and is used to support the ingot blank during the forming process and to eject the finished product from the concave die after the forming is completed; the lower punch is fixed on the upper surface of the base in the forming cavity, the lower punch is provided with a lower ejection rod through hole, and the lower ejection rod is sealingly connected with the lower ejection rod through hole.

[0044] Further, the variable-diameter aluminum alloy pipe is a three-segment wall thickness pipe or a two-segment wall thickness pipe; the outer diameters of the variable-diameter aluminum alloy pipes are consistent,

[0045] The forming inner diameter d of the concave die 凹模 = d 外径 , where d 外径 is the outer diameter of the variable-diameter aluminum alloy pipe, because the final ingot blank will gradually form the outer diameter of the pipe through the inner wall of the concave die;

[0046] The variable-diameter aluminum alloy pipe is a three-segment wall thickness pipe, as shown in Figure 4 , the pipe wall thickness is different from top to bottom, and is B1, B3 and B2 in turn, corresponding to the lengths l1, l3, l2, and in general, B3 is thicker than B1 and B2, and l1 is longer than l3 and l2.

[0047] The height of the lower punch is l2, the height of the lower ejector rod on the base is l2+l3-h, the diameter of the extrusion punch is D1=d 凹模 -2×B1, the diameter of the lower punch is D2=d 凹模 -2×B2, the diameter of the lower ejector rod is D3=d 凹模 -2×B3; wherein h is the forming allowance, l2 and l3 are the lengths of the pipe wall thicknesses B2 and B3 respectively.

[0048] The variable-diameter aluminum alloy pipe material is a two-section wall thickness pipe forming, the pipe wall thicknesses are different from top to bottom, and are B1, B2 in turn, the corresponding lengths are l1, l2 respectively, and generally l1>l2.

[0049] The height of the lower punch is l2, the height of the lower ejector rod on the base is l2+l3-h, the diameter of the extrusion punch is D1=d 凹模 -2×B1, the diameter of the lower punch is D2=d 凹模 -2×B2, the diameter of the lower ejector rod is D3<d;

[0050] wherein h is the forming allowance, d 凹模 is the concave die forming inner diameter, l2 and l3 are the lengths of the pipe wall thicknesses B2 and B3 respectively.

[0051] Further, the concave die forming height h 凹模 =h 锭坯 +(50-70)mm, h 锭坯 is the billet height. Increasing the height by 50-70mm, such as 50mm, 55mm, 60mm, 65mm, 70mm, provides sufficient space for the metal to flow uniformly and completely fill the concave die during extrusion, reducing cavities and defects.

[0052] Further, the extrusion punch forming bottom surface taper α 冲头 =1°-5°, such as 1°, 2°, 3°, 4°, 5°. The presence of the taper helps the metal to better fill the cavity of the die during extrusion, reducing the generation of cavities and cracks. A smaller taper of 1°-5° can reduce the friction of the metal flowing with the punch, reduce the extrusion force, and help the metal flow more uniformly to the outlet of the die, thereby reducing the defects of the extruded part.

[0053] Further, the extrusion punch forming roundness R 冲头 =R3-R8, such as R3, R4, R5, R6, R7, R8. A larger roundness can reduce stress concentration when the metal flows, reducing the risk of breakage of the extruded part. R 冲头 =R3-R8 helps to obtain better surface quality of the extruded part and reduce surface defects.

[0054] Further, the concave die forming wall surface taper α 凹模 The concave die forming wall surface taper is the slope of the inner wall of the concave die from the bottom to the top. The taper helps the smooth flow of the metal in the inner wall of the concave die, reduces the flow resistance and friction. The smaller taper of 0.5°-1° can reduce the adhesion of the metal in the inner wall of the concave die, reduce the drawing force, and reduce the surface damage of the extruded part.

[0055] Further, the heating and heat preservation device is heated and preserved in a surrounding type electric heating pipe heating mode, and a K-type thermocouple is used for temperature control.

[0056] In another aspect, the application discloses a method for forming a variable-diameter aluminum alloy pipe, which uses the forming device described above, and comprises the following steps:

[0057] S1, setting the forming device according to the wall thickness of the target variable-diameter pipe;

[0058] S2, heating the aluminum alloy ingot and the forming device respectively;

[0059] S3, using the set forming device to perform near-isothermal backward extrusion to form a near-net-shape variable-diameter pipe.

[0060] Further, the method is suitable for 2xxx series, 5xxx series, 6xxx series and 7xxx series deformed aluminum alloy materials, and the pipe has an outer diameter ranging from 300 mm to 1000 mm, such as 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm and 1000 mm, and a wall thickness ranging from 25 mm to 100 mm, such as 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm and 100 mm.

[0061] It should be noted that the present application is different from the conventional method of first preparing an equal-wall-thickness pipe and then machining the equal-wall-thickness pipe into a variable-diameter pipe with a variable inner hole. Instead, the present application directly forms a near-net-shape variable-diameter pipe, and the inner hole and wall thickness of the pipe can be accurately adjusted during the forming process to meet the design requirements, which helps to reduce the machining allowance and machining passes at the inner hole, reduces the deformation flow line cut-off, and improves the overall performance of the pipe.

[0062] Further, in S1, the forming device is the forming device of the present application described above, which comprises an extrusion rod, an extrusion punch, a heating and heat preservation device, a concave die, a lower ejector rod and a lower punch;

[0063] The extrusion punch is fixed at the lower end of the extrusion rod; the concave die is fixed on the base of the forming device and is fixed opposite to the base to form a closed forming cavity; the heating and heat preservation device surrounds the concave die; the lower ejecting rod is movably inserted into the hole arranged in the center of the base; the lower convex die is fixed on the upper surface of the base in the forming cavity, and the lower convex die is provided with a lower ejecting rod through hole, and the lower ejecting rod is in sealing connection with the lower ejecting rod through hole.

[0064] Further, in S1, when the forming device is arranged,

[0065] The inner diameter d of the concave die is arranged 凹模 = d 外径 , wherein d 外径 is the outer diameter of the target variable-diameter pipe material;

[0066] The target variable-diameter pipe material is a two-section wall thickness pipe material, the height of the lower convex die and the height of the lower ejecting rod on the base are consistent, and are both l2-h.

[0067] The target variable-diameter pipe material is a three-section wall thickness pipe material, the height of the lower convex die is less than the height of the lower ejecting rod on the base, and the diameter D3 of the lower ejecting rod is arranged as d 凹模 -2×B3.

[0068] Further, in S2, the heating temperature T 锭坯 of the aluminum alloy ingot varies with different ingot materials.

[0069] Specifically, different series of aluminum alloys have different chemical compositions and heat treatment properties. In order to ensure that the strengthening phase in the alloy is fully solid-solved to improve the mechanical properties of the material, the heating temperature generally needs to be higher than the solid solution temperature, but also cannot be too high, so as to avoid causing the low-melting-point phase in the alloy to melt, resulting in a decrease in the material properties.

[0070] In one embodiment, the 2××× series aluminum alloy ingot has T 锭坯 : 420℃-460℃; such as 420℃, 430℃, 440℃, 450℃, 460℃;

[0071] In one embodiment, the 5××× series aluminum alloy ingot has T 锭坯 : 450℃-500℃; such as 450℃, 460℃, 470℃, 480℃, 490℃, 500℃;

[0072] In one embodiment, the 6××× series aluminum alloy ingot has T 锭坯 : 470℃-530℃; such as 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃;

[0073] In one embodiment, the 7××× series aluminum alloy ingot has T锭坯 : 300℃~420℃. Such as 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃;

[0074] Further, in S2, the heating temperature T of the forming device is set to T 装置 ± 20℃; 锭坯 ± 20℃;

[0075] Specifically, the "near isothermal" between the forming device and the aluminum alloy ingot blank helps to reduce thermal stress and thermal shock, while also being beneficial to the optimization of the microstructure and properties of the material. When the temperature difference between the two is too large, it may cause uneven deformation of the material, increasing the risk of cracks and defects. In order to ensure temperature matching during the forming process and ensure the forming quality, the heating temperature T of the forming device is set to T 装置 ± 20℃. 锭坯 ± 20℃.

[0076] Further, in S3, the near-net forming pipe material by reverse extrusion has a forming speed S of 2~6mm / s, such as 2mm / s, 3mm / s, 4mm / s, 5mm / s, 6mm / s, and a forming pressure excess of not less than 15mm, such as 15mm, 18mm, 20mm.

[0077] Specifically, the aluminum alloy has good flowability after heating, but too fast forming speed can easily lead to uneven material flow and defects. The slower forming speed (2~6mm / s) of the present application can ensure that the material has enough time to flow and fill during extrusion, thereby obtaining better forming effect. The forming pressure excess of not less than 15mm can ensure that the material has enough space to fill during extrusion, avoiding the generation of voids and defects.

[0078] Further, S3 includes:

[0079] S301. Put the heated ingot blank into the already heated forming device, specifically into the concave die forming cavity, such as shown in the left figure of Figure 1 ;

[0080] S302. Open the hydraulic machine connected to the extrusion rod, push the extrusion rod to move downward, and the extrusion punch moves downward with the movement of the extrusion rod, directly contacting the ingot blank, applying pressure to the ingot blank, forcing the ingot blank to flow first to the space between the concave die and the lower punch and the lower ejector rod, and then along the inner wall of the concave die to the open end of the concave die. This process is called reverse extrusion.

[0081] S303. Close the hydraulic machine, stop the movement of the extrusion punch, and the forming process is completed.

[0082] S304. Change the pressure direction of the hydraulic machine, push the lower ejector rod to move upward, and eject the formed metal piece from the concave die.

[0083] It should be noted that in order to ensure the forming quality, the forming excess amount should not be less than 15 mm, and after the forming process is completed, the middle part of the extrusion punch and the lower ejecting rod will have a solid cylindrical ingot blank with a thickness of not less than 15 mm, which can help the lower ejecting rod to move upward and eject the formed metal piece from the concave die. After the metal piece is taken out, the cylindrical core needs to be cut off according to the diameter of the lower ejecting rod or the lower punch, so as to pass through the pipe, and then necessary inspection and subsequent processing such as cooling, trimming, etc. are carried out.

[0084] The final ingot is gradually formed into the outer diameter of the pipe through the inner wall of the concave die.

[0085] If the target pipe is a two-section wall thickness pipe, the final ingot is gradually formed into the first inner diameter of the pipe corresponding to the wall thickness B1 through the extrusion punch, and gradually formed into the second inner diameter of the pipe corresponding to the wall thickness B2 through the lower punch. Finally, the aluminum alloy pipe with wall thickness B1 and B2 is formed;

[0086] If the target pipe is a three-section wall thickness pipe, as shown in Figure 4 , the final ingot is gradually formed into the first inner diameter of the pipe corresponding to the wall thickness B1 through the extrusion punch, gradually formed into the second inner diameter of the pipe corresponding to the wall thickness B2 through the lower punch, and gradually formed into the third inner diameter of the pipe corresponding to the wall thickness B3 through the lower ejecting rod. Finally, the aluminum alloy pipe with wall thickness B1, B3 and B2 is formed.

[0087] Further, the first inner diameter is consistent with the diameter D1 of the extrusion punch; the second inner diameter is consistent with the diameter D2 of the lower punch; and the third inner diameter is consistent with the diameter D3 of the lower ejecting rod.

[0088] Compared with the prior art, the present application proposes a special near-net forming variable-diameter pipe device. By means of the device, a near-net forming variable-diameter pipe method is proposed, which not only can near-isothermally reverse extrude and form a variable-diameter aluminum alloy pipe, but also can near-net form a variable-diameter pipe by accurately controlling the deformation temperature and deformation amount. Not only can the machining allowance of the inner hole be reduced and the processing cycle be shortened, but also the deformation flow line cut-off at the inner hole can be reduced and the comprehensive performance of the pipe can be improved. The forming device of the present application is suitable for difficult-to-form materials such as aluminum-based composite materials and magnesium alloys, and has strong universality.

[0089] The present application will be further described below in conjunction with the examples in the specification, but the examples are only for the present application and not limit the present application.

[0090] Example 1

[0091] A forming device of aluminum alloy pipe material, comprising an extrusion rod, an extrusion punch, a heating and heat preservation device, a concave die, a lower ejector rod and a lower punch; the extrusion punch is fixed at the lower end of the extrusion rod, and the extrusion of the extrusion punch on the ingot is realized by the movement of the extrusion rod; the concave die is fixed on the base of the forming device and is fixed opposite to the base to form a closed forming cavity to provide a forming space for the ingot; the inner cavity shape of the forming cavity matches the cross-sectional shape of the aluminum alloy pipe material to be formed; the heating and heat preservation device surrounds the concave die for temperature control; the lower ejector rod is movably inserted into the hole arranged in the center of the base for supporting the ingot during the forming process and ejecting the finished product from the concave die after the forming is completed; the lower punch is fixed on the upper surface of the base in the forming cavity, the lower punch is provided with a lower ejector rod through hole, and the lower ejector rod is sealingly connected with the lower ejector rod through hole.

[0092] The taper of the forming bottom surface of the extrusion punch is α 冲头 = 3°, the forming fillet R 冲头 = R5; the heating and heat preservation device is heated by a surrounding type electric heating pipe, and a K type thermocouple is used; the forming height h 凹模 = 690mm of the concave die, the forming inner diameter d 凹模 = 445mm, the forming wall taper α 凹模 = 1°.

[0093] The forming inner diameter d 凹模 = 445mm of the concave die, the target variable diameter wall thickness B1, B2 and B3 are 25mm, 30mm and 70mm respectively, the corresponding pipe length l2 = 80mm and l3 = 60mm, and the forming pressure allowance h = 15mm, so the diameters of the corresponding extrusion punch, lower punch and lower ejector rod are set to 395mm, 385mm and 305mm respectively, the height of the lower punch is set to l2 = 80mm, and the height of the lower ejector rod on the base is set to l2 + l3 - h = 125mm.

[0094] Example 1-1

[0095] A forming device of aluminum alloy pipe material, and the difference from example 1 is only that the target variable diameter wall thickness B1 and B2 are 25mm and 30mm respectively, the corresponding pipe length l2 = 80mm, and the forming pressure allowance h = 15mm, so the diameters of the corresponding extrusion punch and lower punch are set to 395mm and 385mm respectively, and the heights of the lower punch and the lower ejector rod on the base are uniformly set to l2 - h = 65mm.

[0096] Example 2

[0097] A forming device of aluminum alloy pipe material, and the difference from example 1 is only that the taper of the forming bottom surface of the extrusion punch is α 冲头 = 2°; the forming height h 凹模= 700 mm, forming inner diameter d 凹模 = 560 mm, forming wall surface taper α 凹模 = 0.5°.

[0098] Through the concave mold forming inner diameter d 凹模 = 560 mm, target variable diameter wall thickness B1, B2, B3 are 25, 60, 70 mm respectively, corresponding pipe length l2 = 120 mm, l3 = 70 mm, forming pressure allowance h = 15 mm, it can be calculated that the corresponding extrusion punch, lower punch and lower ejector rod diameter are set to 510 mm, 440 mm, 420 mm respectively, the height of the lower punch is set to l2 = 120 mm, and the height of the lower ejector rod on the base is set to l2 + l3 - h = 175 mm.

[0099] Example 3

[0100] A forming device for an aluminum alloy pipe, and the difference from example 1 is only that the extrusion punch forming bottom surface taper α 冲头 = 5°, forming roundness R 冲头 = R8; forming wall surface taper α 凹模 = 0.8°.

[0101] Example 4

[0102] A 7A99 aluminum alloy pipe, the forming pipe outer diameter Ф445 mm, variable diameter wall thickness B1, B2, B3 are 25 mm, 30 mm, 70 mm respectively, corresponding pipe length l2 = 80 mm, l3 = 60 mm, the pipe forming method is carried out by means of the forming device of example 1, and the device is shown as Figure 5 (right) is directly near net forming into a variable diameter pipe, the inner hole and wall thickness of the pipe can be accurately adjusted during the forming process to meet the design requirements, which helps to reduce the machining allowance and machining passes at the inner hole, including the following steps:

[0103] Step 1: aluminum alloy ingot with diameter d 锭坯 = 435 mm, height h 锭坯 = 630 mm is heated to 350℃;

[0104] Step 2: heat the forming device to 360℃.

[0105] Step 3: After the forming device is heated, the heated aluminum alloy ingot is placed at the bottom of the concave die of the device. The near-net forming variable-diameter pipe is formed by near-isothermal backward extrusion at a forming speed of 3 mm / s, and the forming pressure surplus is ensured to be not less than 15 mm to ensure the forming quality. The final ingot is gradually formed into a pipe with a first wall thickness of 25 mm, a second wall thickness of 30 mm, and a third wall thickness of 70 mm by the extrusion punch, the lower punch, and the lower ejector rod. The formed pipe is ejected from the concave die by the lower ejector rod. The solid cylindrical core formed by the forming pressure surplus in the middle part of the pipe is cut off according to the diameter of the lower ejector rod to pass through the pipe.

[0106] Example 5

[0107] A 6061 aluminum alloy pipe with an outer diameter of Ф560 mm, variable-diameter wall thicknesses of B1, B2, and B3 of 25 mm, 60 mm, and 70 mm, respectively, and corresponding pipe lengths of l2=120 mm and l3=70 mm is formed by the forming method of Example 2, which includes the following steps:

[0108] Step 1: An aluminum alloy ingot with a diameter d 锭坯 =550 mm and a height h 锭坯 =650 mm is heated to 485℃;

[0109] Step 2: The forming device is heated to 480℃.

[0110] Step 3: After the forming device is heated, the heated aluminum alloy ingot is placed at the bottom of the concave die of the device. The near-net forming variable-diameter pipe is formed by near-isothermal backward extrusion at a forming speed of 3 mm / s, and the forming pressure surplus is ensured to be not less than 15 mm to ensure the forming quality. The final ingot is gradually formed into a pipe with a first wall thickness of 25 mm, a second wall thickness of 60 mm, and a third wall thickness of 70 mm by the extrusion punch, the lower punch, and the lower ejector rod. The formed pipe is ejected from the concave die by the lower ejector rod. The solid cylindrical core formed by the forming pressure surplus in the middle part of the pipe is cut off according to the diameter of the lower ejector rod to pass through the pipe.

[0111] Example 6

[0112] A 7A99 aluminum alloy pipe is formed by the forming method of Example 1-1, which is different from Example 4 in that the variable-diameter wall thicknesses B1 and B2 are 25 mm and 30 mm, respectively, and the corresponding pipe length l2=80 mm. The forming method includes the following steps:

[0113] Steps 1 and 2 are the same as those of Example 4;

[0114] Step 3: The difference from Example 4 is that the forming speed is 4 mm / s, and the final billet is gradually formed into a pipe with a first wall thickness of 25 mm and a second wall thickness of 30 mm by an extrusion punch and a lower punch.

[0115] Comparative Example 1

[0116] A 7A99 aluminum alloy pipe, and the difference from Example 4 is that a conventional pipe forming method is used, such as Figure 5 (Left) is to first prepare an equal-wall-thickness pipe, and then machine the equal-wall-thickness pipe along the dashed line to form a pipe with a variable inner hole diameter.

[0117] Characterization tests

[0118] The flow line diagram of the variable-diameter pipe prepared by the conventional method of Comparative Example 1 is shown in Figure 6 (Left), due to the cutting effect of machining, the original flow line of the material is cut off, resulting in the integrity and performance of the material being affected, and under the action of force 8, a crack 9 is generated at the concave corner. It is shown that the conventional method is prone to cracking failure, in addition, the machining allowance of the material is large, and the machining passes are many.

[0119] The flow line diagram of the variable-diameter pipe prepared by the method of Example 4 of the present application is shown in Figure 6 (Right), the deformed flow line at the inner hole is distributed along the maximum outer contour, the flow line is continuous and not cut off, and no crack is generated at the concave corner under the action of external force. It is shown that the method of the present application is not prone to cracking failure, improves the overall performance of the pipe, in addition, near-net forming, machining allowance is small, and material utilization rate is high.

[0120] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A reducing aluminum alloy tube forming apparatus characterized by comprising: The extrusion punch is fixed at the lower end of the extrusion rod, and the extrusion of the extrusion punch on the ingot blank is realized by the movement of the extrusion rod. The extrusion punch is fixed at the lower end of the extrusion rod, and the extrusion of the extrusion punch on the ingot blank is realized by the movement of the extrusion rod. The inner cavity shape of the forming cavity matches the cross-sectional shape of the aluminum alloy pipe to be formed; the heating and heat preservation device surrounds the concave die and controls the temperature; the lower ejector rod can be movably inserted into the hole arranged in the center of the base, used to support the ingot blank during the forming process, and to eject the finished product from the concave die after the forming is completed; the lower punch is fixed on the upper surface of the base in the forming cavity, the lower punch is provided with a lower ejector rod through hole, and the lower ejector rod and the lower ejector rod through hole are in sealing connection. The variable-diameter aluminum alloy pipe is a three-section wall thickness pipe or a two-section wall thickness pipe; the variable-diameter aluminum alloy pipe has a consistent outer diameter, diameter of the female die 凹模 = d 外径 where d 外径 is the outside diameter of the variable diameter aluminum alloy tube The variable-diameter aluminum alloy pipe is a three-section wall thickness pipe, the pipe wall thickness from top to bottom is B1, B3, B2 in turn, the height of the lower punch is l2, the height of the lower ejection rod on the base is l2+l3-h, the diameter D1 of the extrusion punch is d 凹模 -2×B1, the diameter D2 of the lower punch is d 凹模 -2×B2, the diameter D3 of the lower ejection rod is d 凹模 -2×B3; Wherein h is the forming pressure surplus, l2 and l3 are the pipe lengths corresponding to the pipe wall thicknesses B2 and B3 respectively.

2. The forming device of claim 1, wherein The variable-diameter aluminum alloy pipe is formed by two-section wall thickness pipe, and the pipe wall thicknesses from top to bottom are B1, B2 in sequence, the height of the lower punch and the height of the lower ejector rod on the base are consistent, both are l2-h, the diameter D1 of the extrusion punch is d 凹模 -2×B1, the diameter D2 of the lower punch is d 凹模 -2×B2, the diameter D3 of the lower ejector rod is less than D2; Where h is the forming pressure margin, d 凹模 is the inner diameter of the die, and l2 is the tube length corresponding to the tube wall thickness B2.

3. The forming device of claim 1, wherein The extrusion punch forms a bottom surface taper α 冲头 =1°~5°, forms a round corner R 冲头 =R3~R8; the concave die forms a wall surface taper α 凹模 0.5°~1°.

4. A method of forming a variable diameter aluminum alloy tube, the method comprising: The forming device of any one of claims 1-3 is adopted, comprising the following steps: S1, setting the forming device according to the wall thickness of the target variable-diameter pipe; S2, heating the aluminum alloy ingot blank and the forming device respectively; S3, using the set forming device to near-net form the variable-diameter pipe by near-isothermal backward extrusion.

5. The forming method of claim 4, wherein, In S1, the target variable-diameter pipe is a two-section wall thickness pipe, and the height of the lower punch and the height of the lower ejector rod on the base are consistent.

6. The forming method of claim 4, wherein In S1, the target variable diameter pipe is a three-stage wall thickness pipe, and the wall thickness from top to bottom is B1, B3, and B2. The height of the lower punch is set to be smaller than the height of the lower ejector rod on the base, and the diameter of the lower ejector rod is set to D3 = d 凹模 -2×B3, where d 凹模 The inner diameter of the die is formed.

7. The forming method of claim 4 wherein, In S2, the forming device is heated to a temperature T 装置 T is between 50 and 150°C 锭坯 ±20°C.

8. The forming method of claim 4, wherein, In S3, the near-isothermal backward extrusion near-net forming variable-diameter pipe has a forming speed S of 2-6 mm / s, and a forming pressure surplus of not less than 15 mm.

9. The forming method of claim 4, wherein S3 Comprising: S301. Put the heated ingot blank into the concave die forming cavity in the heated forming device; S302. Open the hydraulic machine connected with the extrusion rod, push the extrusion rod to drive the extrusion punch downward, apply pressure to the ingot blank, and the ingot blank first flows to the space between the concave die and the lower punch and the lower ejector rod, and then flows along the inner wall of the concave die to the opening end of the concave die; S303. Close the hydraulic machine, and the extrusion punch stops moving, and the forming process is completed; S304. Change the pressure direction of the hydraulic machine to push the lower ejector rod to move upward, and eject the formed metal piece from the concave die.

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