A forming method of large-thickness-difference, multi-step long straight no-weld aluminum alloy cylindrical part

Abstract

The application provides a forming method of a large-thickness-difference, multi-step long straight weldless aluminum alloy cylindrical piece, and relates to the field of aluminum alloy cylindrical piece forming. When forming a large-thickness-difference, multi-step thin-walled weldless aluminum alloy cylindrical piece, the prior art is often restricted in many aspects, and the formed aluminum alloy cylindrical piece is difficult to meet the requirements. Therefore, the application provides a novel method, which comprises the following steps: performing multi-pass spinning on a pipe blank, and interspersing annealing heat treatment of the pipe blank in the spinning process; wherein three spinning wheels are used to spin the pipe blank, and the parameters of the spinning wheels are as follows: an entry spinning angle is 10-30 DEG, an exit spinning angle is 10-20 DEG, a forming radius is 15-30 mm, a diameter is 450-550 mm, and the thickness is 60-80 mm. The inner diameter deviation of the 5-series aluminum alloy cylindrical piece prepared by using the forming method is less than or equal to 0.5, the roundness deviation is less than or equal to 0.5, the straightness deviation is less than or equal to 0.5, the yield strength is greater than 175 MPa, the tensile strength is greater than 340 MPa, and the elongation is greater than 25%.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy cylindrical parts forming, and in particular to a method for forming long, straight, weld-free aluminum alloy cylindrical parts with large thickness differences and multiple steps. Background Technology

[0002] Currently, the main technologies are: plate rolling + longitudinal weld + thick step welding, and extruding thick tubes + machining into thin tubes + thick step welding.

[0003] 1. Plate rolling + longitudinal weld + thick step welding: (1) Plate rolling has poor roundness and requires multiple reshaping; (2) Longitudinal weld + thick step welding has a long welding time and requires subsequent weld quality inspection, which is very complicated and has low production efficiency, and cannot meet the needs of mass production.

[0004] 2. Extrusion of thick tubes + machining into thin tubes + welding: (1) It is difficult to extrude seamless tubes into thin tubes. It is difficult to achieve an extrusion thickness of less than 5% for a diameter of 300mm, and it is generally more than 10mm. It is often extruded into thick-walled tubes and then machined into thin-walled tubes. (2) It is also difficult to extrude thick-walled tubes and then machine them into thin-walled tubes. It is difficult to control the roundness and straightness. Thus, the extrusion is very difficult, the machining is very difficult, the material utilization rate is very low, the production efficiency is very low, and it is impossible to meet the needs of mass production.

[0005] Spin forming also presents some challenges: (1) Spin forming is used for thick-walled tubes: no spinning is done where there are steps, and spinning is done where there are thin walls. This presents a problem: the spun areas may have increased or decreased diameters, resulting in inconsistent dimensions with the non-spun areas; this places demands on the spinning process; (2) Spin forming is a localized process, and the roundness and straightness may need to be ensured through the process, which places high demands on the spinning process; (3) 5-series aluminum alloys are prone to hardening during spin forming, requiring multiple annealing passes; this places demands on the annealing process.

[0006] In summary, there is an urgent need for a method to form large-sized, multi-step, thin-walled, weld-free aluminum alloy cylindrical parts. Summary of the Invention

[0007] To address the aforementioned problems, the first aspect of this invention provides a forming method for a long, straight, weldless aluminum alloy cylindrical part with a large thickness difference and multiple steps, which can solve the problems of diameter expansion or contraction, as well as insufficient roundness and straightness accuracy, that occur during the processing of aluminum alloy cylindrical parts with large thickness differences.

[0008] The first aspect of this invention provides a method for forming a long, straight, weldless aluminum alloy cylindrical part with large thickness difference and multiple steps. The method includes: performing multiple spinning operations on the tube blank, with annealing heat treatment interspersed during the spinning process; wherein, three spinning wheels are used to spin the tube blank, and the parameters of the spinning wheels are as follows: the infeed angle is 10~30°, the outfeed angle is 10~20°, the forming radius is 15~30 mm, the diameter is 450~550 mm, and the thickness is 60~80 mm.

[0009] In one feasible embodiment, the tube blank is spun in three or four passes; the same spinning wheel is used for the first and second spinning passes, and the same spinning wheel is used for the third and fourth spinning passes.

[0010] In one feasible embodiment, the parameters of the spinning wheels used in the first and second spinning processes are as follows: inlet spin angle of 18~30°, outlet spin angle of 10~20°, forming radius of 15~30 mm, diameter of 450~550 mm, thickness of 60~80 mm, rotation speed of 50~100 rpm, feed rate of 0.5~2 mm / rpm, reduction of 2~6 mm, and offset between the spinning wheels of 10~15 mm; the parameters of the spinning wheels used in the third and fourth spinning processes are as follows: inlet spin angle of 10~24°, outlet spin angle of 10~20°, forming radius of 15~30 mm, diameter of 450~550 mm, thickness of 60~80 mm, rotation speed of 50~100 rpm, feed rate of 0.5~2 mm / rpm, reduction of 2~6 mm, and offset between the spinning wheels of 3~8 mm.

[0011] In one feasible embodiment, during the three-stage and four-stage spinning processes, the parameters of the three spinning wheels are as follows: First spinning wheel: inlet angle 20°, outlet angle 18°, forming radius 20 mm, diameter 500 mm, thickness 80 mm, rotation speed 60 rpm, feed 1 mm / rpm, reduction 2 mm, and offset between the spinning wheels 6 mm; Second spinning wheel: inlet angle 16°, outlet angle 18°, forming radius 20 mm, diameter 500 mm, thickness 80 mm, rotation speed 60 rpm, feed 1 mm / rpm, reduction 2 mm, and offset between the spinning wheels 6 mm; Third spinning wheel: inlet angle 12°, outlet angle 18°, forming radius 20 mm, diameter 500 mm, thickness 80 mm, rotation speed 60 rpm, feed 1 mm / rpm, reduction 2 mm, and offset between the spinning wheels 6 mm.

[0012] In one feasible embodiment, after each spinning pass, the tube blank is subjected to annealing heat treatment; wherein, the annealing heat treatment temperature is 400~550 ℃ and the annealing time is 0.5~8 hours.

[0013] In one feasible embodiment, the thinning amount of the first-order spinning is 30-40%; the thinning amount of the second-order spinning is 30-40%; the thinning amount of the third-order spinning is 20-40%; and the thinning amount of the fourth-order spinning is 10-20%.

[0014] In one feasible embodiment, the spun tube blank is post-processed to obtain a finished tube blank; wherein, the post-processing includes residual stress heat treatment, precision machining, and stabilization treatment.

[0015] In one feasible embodiment, before the formal spinning is performed, a buffer groove is first spun out in front of and / or behind the preset step position of the tube blank to form a step; during the spinning process, each section of the tube blank is spun separately with the step as the dividing line; the starting position and the ending position of the spinning of each section of the tube blank are both buffer grooves.

[0016] The second aspect of the present invention provides a thin-walled, weld-free aluminum alloy cylinder with a large thickness difference and multiple steps, which is prepared by the method provided in the first aspect of the present invention; wherein the difference between the maximum and minimum wall thickness of the aluminum alloy cylinder is 6 to 7 times; preferably, the maximum wall thickness of the aluminum alloy cylinder is greater than 30 mm and the minimum wall thickness is less than 5 mm.

[0017] In one feasible embodiment, the seamless aluminum alloy cylinder is a 5-series aluminum alloy with an inner diameter deviation ≤ ±0.5, a roundness deviation ≤ 0.5, a straightness deviation ≤ 0.5, a yield strength greater than 175 MPa, a tensile strength greater than 340 MPa, and an elongation greater than 25%.

[0018] The forming method for long, straight, weld-free aluminum alloy cylindrical parts with large thickness variations and multiple steps provided by this invention has the following beneficial effects: The aluminum alloy cylindrical parts prepared by this invention, especially 5-series aluminum alloy cylindrical parts, have the characteristics of low straightness deviation, low roundness deviation, low inner diameter deviation, and high elongation. Specifically, the 5-series aluminum alloy cylindrical parts prepared by this invention have an inner diameter deviation ≤ ±0.5, a roundness deviation ≤ 0.5, a straightness deviation ≤ 0.5, a yield strength greater than 175 MPa, a tensile strength greater than 340 MPa, and an elongation greater than 25%. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the rotating wheel in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the blank in an embodiment of the present invention.

[0021] Figure 3 This is a cross-sectional view of the blank in an embodiment of the present invention.

[0022] Figure 4This is a schematic diagram of the structure of a long, straight, weldless aluminum alloy cylindrical component with large thickness difference and multiple steps in an embodiment of the present invention.

[0023] Figure 5 As described in the embodiments of the present invention Figure 2 Cross-sectional view.

[0024] Figure 6 As described in the embodiments of the present invention Figure 2 Partial cross-sectional view. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "inflection angle," "outflection angle," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, 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.

[0027] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0029] Before providing a further detailed description of the present invention, the nouns and terms used in the embodiments of the present invention are explained, and the nouns and terms used in the embodiments of the present invention are subject to the following interpretations:

[0030] <1> Spinning: Spinning is a point-continuous, localized plastic forming process. Its basic principle is: a metal plate or preform (circular sheet or tube) is clamped on the mandrel of the spinning machine and rotated together with the spindle. Then, one or more pressure-applying rollers feed the blank point by point in a continuous radial or axial manner along a preset trajectory.

[0031] <2> Strong spinning thinning: Specifically refers to the process in which a spinning wheel applies enormous radial pressure to a rotating billet during a strong spinning process, forcing the material to extend circumferentially and elongate axially, thereby achieving a regular and significant reduction in wall thickness.

[0032] <3> Spinning wheel: A forming tool on a spinning machine that applies localized, continuous, and controllable pressure to a rotating metal billet. The working principle of the spinning wheel is to extrude and roll the metal billet, with key parameters including the forming radius, the infeed angle, and the outfeed angle.

[0033] <4> Angle of attack (also known as the rake angle or angle of attack). It is the angle between the rake's forward-tilting surface and the workpiece's formed surface. The surface at the angle of attack is the guiding surface, pointing in the direction of the rake's forward movement. In the normal spinning feed direction, the rake's forward-tilting surface, where the angle of attack is located, always contacts the workpiece first.

[0034] <5> Exit angle: also known as back angle. It is the angle between the back slope of the spinning wheel and the forming surface of the workpiece. The surface with the exit angle β is the following surface, facing the area that has already been formed or contacted. In the normal spinning feed direction, the back slope surface where the exit angle of the spinning wheel is located is always the last to contact the workpiece.

[0035] <6> Forming radius: The radius of the rounded corner at the top of the working part of the spinning wheel, where the pressure peaks and the material undergoes the most significant plastic deformation and thinning.

[0036] This invention provides a method for forming a long, straight, weld-free aluminum alloy cylindrical part with large thickness variations and multiple steps, aiming to address two key problems in the spinning process of cylindrical parts. The first problem is that spinning can cause the cylindrical part to expand or shrink in diameter, especially for cylindrical parts with large thickness variations and multiple steps. The areas where the part is spun will expand or shrink, resulting in a significant diameter difference between the spun and unspun areas. The second problem is that as the wall thickness of the cylindrical part decreases during spinning, its roundness and straightness become increasingly difficult to control.

[0037] Therefore, the present invention provides a forming method for a long, straight, weldless aluminum alloy cylindrical part with large thickness difference and multiple steps, aiming to solve the above two problems. The method includes:

[0038] The tube blank is spun in multiple passes, with annealing heat treatment interspersed during the spinning process. Three spinning wheels are used to spin the tube blank, and the parameters of the spinning wheels are as follows: the infeed angle is 10~30°, the outfeed angle is 10~20°, the forming radius is 15~30 mm, the diameter is 450~550 mm, and the thickness is 60~80 mm.

[0039] In one example embodiment, the tube blank is spun in three or four passes. The same spinning wheel is used for the first and second spinning passes, and the same spinning wheel is used for the third and fourth spinning passes.

[0040] Specifically, the parameters of the spinning wheels used in the first-order spinning and second-order spinning are as follows: the inlet spin angle is 18~30°, the outlet spin angle is 10~20°, the forming radius is 15~30 mm, the diameter is 450~550 mm, the thickness is 60~80 mm, the rotation speed is 50~100 rpm, the feed is 0.5~2 mm / revolution, the reduction is 2~6 mm, and the offset between the spinning wheels is 10~15 mm.

[0041] Preferably, the incident angle is any one of 18~22°, 22~26°, or 26~30°.

[0042] Preferably, the spin angle is any one of 10~12°, 12~14°, 14~16°, 16~18°, and 18~20°.

[0043] Preferably, the forming radius is any one of 15~20 mm, 20~25 mm, or 25~30 mm.

[0044] Preferably, the diameter is any one of 450~480 mm, 480~510 mm, 510~540 mm, and 540~550 mm.

[0045] Preferably, the thickness is any one of 60~65 mm, 65~70 mm, 70~75 mm, and 75~80 mm.

[0046] Preferably, the rotational speed is any one of 50~70 rpm, 70~90 rpm, or 90~100 rpm.

[0047] Preferably, the feed rate is any one of 0.5~2 mm / revolution, 1~1.5 mm / revolution, or 1.5~2 mm / revolution.

[0048] Preferably, the compression amount is any one of 2~3 mm, 3~4 mm, 4~5 mm, and 5~6 mm.

[0049] Preferably, the offset between the rotating wheels is any one of 10~12 mm, 12~14 mm, or 14~15 mm.

[0050] Specifically, the parameters of the spinning wheels used in the three-stage spinning and four-stage spinning are as follows: the infeed angle is 10~24°, the outfeed angle is 10~20°, the forming radius is 15~30 mm, the diameter is 450~550 mm, the thickness is 60~80 mm, the rotation speed is 50~100 rpm, the feed is 0.5~2 mm / rpm, the reduction is 2~6 mm, and the offset between the spinning wheels is 3~8 mm.

[0051] Preferably, the incident angle is any one of 10~14°, 14~18°, 18~22°, and 22~24°.

[0052] Preferably, the spin angle is any one of 10~12°, 12~14°, 14~16°, 16~18°, and 18~20°.

[0053] Preferably, the forming radius is any one of 15~20 mm, 20~25 mm, or 25~30 mm.

[0054] Preferably, the diameter is any one of 450~480 mm, 480~510 mm, 510~540 mm, and 540~550 mm.

[0055] Preferably, the thickness is any one of 60~65 mm, 65~70 mm, 70~75 mm, and 75~80 mm.

[0056] Preferably, the rotational speed is any one of 50~70 rpm, 70~90 rpm, or 90~100 rpm.

[0057] Preferably, the feed rate is any one of 0.5~2 mm / revolution, 1~1.5 mm / revolution, or 1.5~2 mm / revolution.

[0058] Preferably, the compression amount is any one of 2~3 mm, 3~4 mm, 4~5 mm, and 5~6 mm.

[0059] Preferably, the offset between the rotating wheels is any one of 10~12 mm, 12~14 mm, or 14~15 mm.

[0060] Specifically, the thinning amount of the first-order spinning is 30-40%; the thinning amount of the second-order spinning is 30-40%; the thinning amount of the third-order spinning is 20-40%; and the thinning amount of the fourth-order spinning is 10-20%.

[0061] Furthermore, after each spinning pass, the tube blank is subjected to annealing heat treatment; wherein the annealing heat treatment temperature is 400~550 ℃ and the annealing time is 0.5~8 hours.

[0062] Furthermore, the temperature for the first-stage annealing heat treatment is 420~450 ℃, and the annealing time is 1~2 hours; the temperature for the second-stage annealing heat treatment is 450~480 ℃, and the annealing time is 2~3 hours; the temperature for the third-stage annealing heat treatment is 480~510 ℃, and the annealing time is 3~4 hours; and the temperature for the fourth-stage annealing heat treatment is 500~530 ℃, and the annealing time is 4~6 hours.

[0063] Furthermore, before the formal spinning process, buffer grooves are first spun out in front of and / or behind the predetermined step position on the tube blank to form the step. During the spinning process, each section of the tube blank is spun separately, with the step as the dividing point. The starting and ending positions of the spinning for each section of the tube blank are both buffer grooves. For example, for steps located at both ends of the tube blank, it is only necessary to spin out buffer grooves in front of or behind the predetermined step position to form the step; for steps located in the middle of the tube blank, it is necessary to spin out buffer grooves in front of and behind the predetermined step position to form the step. The depth of the buffer groove is consistent with the feed depth of the last spinning pass; in other words, the wall thickness at the buffer groove is consistent with the wall thickness of the finished tube blank.

[0064] Furthermore, the spun tube blank is subjected to post-processing to obtain the finished tube blank; wherein, the post-processing includes residual stress heat treatment, precision machining, and stabilization treatment.

[0065] A second aspect of this invention provides a long, straight, weldless aluminum alloy cylindrical component with a large thickness difference and multiple steps, prepared using the method provided in the first aspect of this invention. The difference between the maximum and minimum wall thickness of the aluminum alloy cylinder is 6-7 times; preferably, the maximum wall thickness is greater than 30 mm, and the minimum wall thickness is less than 5 mm. Further, the weldless aluminum alloy cylinder is a 5-series aluminum alloy with an inner diameter deviation ≤ ±0.5, a roundness deviation ≤ 0.5, a straightness deviation ≤ 0.5, a yield strength greater than 175 MPa, a tensile strength greater than 340 MPa, and an elongation greater than 25%.

[0066] Example 1

[0067] In this embodiment, a 5-series aluminum alloy cylindrical part, as shown in Figures 2 and 3, is used for spinning to prepare a long, straight, weld-free aluminum alloy cylindrical part with large thickness differences and multiple steps. The spinning process employs four passes, and the parameters of the spinning wheel used in each pass are as follows:

[0068] In a single-stage spinning process, the three spinning wheels are of the same size, and the specific parameters are as follows:

[0069] The inlet swirl angle is 26°, the outlet swirl angle is 16°, the forming radius is 25 mm, the diameter is 500 mm, the thickness is 70 mm, the rotation speed is 60 rpm, the feed is 1.2 mm / rpm, the reduction is 5 mm, and the offset between the swirls is 14 mm.

[0070] The temperature for the first-stage annealing heat treatment was 420 ℃, and the annealing time was 1 hour;

[0071] In the two-stage spinning process, the three spinning wheels are of the same size, and the specific parameters are as follows:

[0072] The inlet swirl angle is 24°, the outlet swirl angle is 15°, the forming radius is 22 mm, the diameter is 500 mm, the thickness is 70 mm, the rotation speed is 70 rpm, the feed is 1.0 mm / rpm, the reduction is 4 mm, and the offset between the swirls is 12 mm.

[0073] The second-stage annealing heat treatment temperature is 450 ℃, and the annealing time is 2 hours.

[0074] The parameters of the three spinning wheels used in three-stage and four-stage spinning are as follows:

[0075] First rotating wheel: inlet angle is 20°, outlet angle is 18°, forming radius is 20 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 60 rpm, feed is 1 mm / rpm, pressing amount is 2 mm, and the offset between rotating wheels is 6 mm.

[0076] Second rotating wheel: inlet angle is 16°, outlet angle is 18°, forming radius is 20 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 60 rpm, feed is 1 mm / rpm, pressing amount is 2 mm, and the offset between rotating wheels is 6 mm.

[0077] Third rotating wheel: 12° entry angle, 18° exit angle, forming radius 20 mm, diameter 500 mm, thickness 80 mm, rotation speed 60 rpm, feed rate 1 mm / rpm, reduction 2 mm, and offset between rotating wheels 6 mm.

[0078] The three-stage annealing heat treatment temperature is 480 ℃, and the annealing time is 3 hours;

[0079] The temperature for the four-stage annealing heat treatment is 500 ℃, and the annealing time is 4 hours.

[0080] The final manufactured aluminum alloy cylindrical part with large thickness difference, multi-step, long straight, and weldless structure is shown in Figures 4 and 5. The maximum wall thickness is 31.7 mm, the minimum wall thickness is 3.1 mm, the inner diameter deviation is 0.30 mm, the roundness deviation is 0.32 mm, the straightness deviation is 0.35 mm, the yield strength is 186 MPa, the tensile strength is 352 MPa, and the elongation is 28%. In Figure 6, D1 represents the minimum wall thickness, and D2 represents the maximum wall thickness.

[0081] Example 2

[0082] In this embodiment, a 5-series aluminum alloy cylindrical part, as shown in Figures 2 and 3, is used for spinning to prepare a long, straight, weld-free aluminum alloy cylindrical part with large thickness differences and multiple steps. The spinning process employs four passes, and the parameters of the spinning wheel used in each pass are as follows:

[0083] In a single-stage spinning process, the three spinning wheels are of the same size, and the specific parameters are as follows:

[0084] The inlet swirl angle is 28°, the outlet swirl angle is 18°, the forming radius is 28 mm, the diameter is 520 mm, the thickness is 75 mm, the rotation speed is 55 rpm, the feed is 1.5 mm / rpm, the reduction is 6 mm, and the offset between the swirls is 15 mm.

[0085] The temperature for the first-stage annealing heat treatment was 430 ℃, and the annealing time was 1.5 hours;

[0086] In the two-stage spinning process, the three spinning wheels are of the same size, and the specific parameters are as follows:

[0087] The inlet swirl angle is 22°, the outlet swirl angle is 14°, the forming radius is 20 mm, the diameter is 480 mm, the thickness is 65 mm, the rotation speed is 80 rpm, the feed is 0.8 mm / rpm, the reduction is 3 mm, and the offset between the swirls is 11 mm.

[0088] The second-stage annealing heat treatment temperature is 460 ℃, and the annealing time is 2.5 hours;

[0089] The parameters of the three spinning wheels used in three-stage and four-stage spinning are as follows:

[0090] First rotating wheel: inlet angle is 20°, outlet angle is 18°, forming radius is 20 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 60 rpm, feed is 1 mm / rpm, pressing amount is 2 mm, and the offset between rotating wheels is 6 mm.

[0091] Second rotating wheel: inlet angle is 16°, outlet angle is 18°, forming radius is 20 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 60 rpm, feed is 1 mm / rpm, pressing amount is 2 mm, and the offset between rotating wheels is 6 mm.

[0092] Third rotating wheel: 12° entry angle, 18° exit angle, forming radius 20 mm, diameter 500 mm, thickness 80 mm, rotation speed 60 rpm, feed rate 1 mm / rpm, reduction 2 mm, and offset between rotating wheels 6 mm.

[0093] The three-stage annealing heat treatment temperature is 480 ℃, and the annealing time is 3 hours;

[0094] The temperature for the four-stage annealing heat treatment is 500 ℃, and the annealing time is 4 hours.

[0095] The final produced aluminum alloy cylindrical part with large thickness difference, multi-step, long straight, and weldless structure is shown in Figures 4 and 5. The maximum wall thickness is 30.0 mm, the minimum wall thickness is 4.0 mm, the inner diameter deviation is 0.25 mm, the roundness deviation is 0.28 mm, the straightness deviation is 0.30 mm, the yield strength is 192 MPa, the tensile strength is 360 MPa, and the elongation is 27%.

[0096] Example 3

[0097] In this embodiment, a 5-series aluminum alloy cylindrical part, as shown in Figures 2 and 3, is used for spinning to prepare a long, straight, weld-free aluminum alloy cylindrical part with large thickness differences and multiple steps. The spinning process employs four passes, and the parameters of the spinning wheel used in each pass are as follows:

[0098] In a single-stage spinning process, the three spinning wheels are of the same size, and the specific parameters are as follows:

[0099] The inlet swirl angle is 25°, the outlet swirl angle is 15°, the forming radius is 24 mm, the diameter is 500 mm, the thickness is 70 mm, the rotation speed is 65 rpm, the feed is 1.1 mm / rpm, the reduction is 4.8 mm, and the offset between the swirls is 13 mm.

[0100] The temperature for the first-stage annealing heat treatment was 410 ℃, and the annealing time was 0.8 hours;

[0101] In the two-stage spinning process, the three spinning wheels are of the same size, and the specific parameters are as follows:

[0102] The inlet swirl angle is 23°, the outlet swirl angle is 14°, the forming radius is 21 mm, the diameter is 500 mm, the thickness is 70 mm, the rotation speed is 75 rpm, the feed is 0.9 mm / rpm, the reduction is 3.8 mm, and the offset between the swirls is 11 mm.

[0103] The second-stage annealing heat treatment temperature is 440 ℃, and the annealing time is 1.5 hours;

[0104] The parameters of the three spinning wheels used in the three-stage spinning process are as follows:

[0105] First rotating wheel: inlet angle is 19°, outlet angle is 17°, forming radius is 19 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 65 rpm, feed is 0.9 mm / rpm, pressing amount is 1.8 mm, and the offset between rotating wheels is 5.5 mm.

[0106] Second rotating wheel: inlet angle is 15°, outlet angle is 17°, forming radius is 19 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 65 rpm, feed is 0.9 mm / rpm, pressing amount is 1.8 mm, and the offset between rotating wheels is 5.5 mm.

[0107] The third rotating wheel has an inlet angle of 11°, an outlet angle of 17°, a forming radius of 19 mm, a diameter of 500 mm, a thickness of 80 mm, a rotation speed of 65 rpm, a feed rate of 0.9 mm / rpm, a reduction of 1.8 mm, and a stagger between the rotating wheels of 5.5 mm. The third-stage annealing heat treatment temperature is 470 ℃, and the annealing time is 2.5 hours.

[0108] The parameters of the three spinning wheels used in the four-stage spinning process are as follows:

[0109] First rotating wheel: inlet angle is 18°, outlet angle is 16°, forming radius is 18 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 70 rpm, feed is 0.8 mm / rpm, pressing amount is 1.5 mm, and the offset between rotating wheels is 5 mm.

[0110] Second rotating wheel: inlet angle is 14°, outlet angle is 16°, forming radius is 18 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 70 rpm, feed is 0.8 mm / rpm, pressing amount is 1.5 mm, and the offset between rotating wheels is 5 mm.

[0111] The third rotating wheel has an inlet angle of 10°, an outlet angle of 16°, a forming radius of 18 mm, a diameter of 500 mm, a thickness of 80 mm, a rotation speed of 70 rpm, a feed rate of 0.8 mm / rpm, a reduction of 1.5 mm, and a stagger between the rotating wheels of 5 mm.

[0112] The four-stage annealing heat treatment is performed at a temperature of 500 ℃ for 3.5 hours.

[0113] The final produced aluminum alloy cylindrical part with large thickness difference, multi-step, long straight, and weldless structure is shown in Figures 4 and 5. The maximum wall thickness is 30.5 mm, the minimum wall thickness is 3.2 mm, the inner diameter deviation is 0.28 mm, the roundness deviation is 0.30 mm, the straightness deviation is 0.33 mm, the yield strength is 182 MPa, the tensile strength is 348 MPa, and the elongation is 27%.

[0114] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for forming a long, straight, weld-free aluminum alloy cylindrical part with large thickness difference and multiple steps, characterized in that, include: The tube blank is spun in multiple passes, with annealing heat treatment interspersed during the spinning process; specifically, three spinning wheels are used to spin the tube blank, and the parameters of the spinning wheels are as follows: The inlet spiral angle is 10~30°, the outlet spiral angle is 10~20°, the forming radius is 15~30 mm, the diameter is 450~550 mm, and the thickness is 60~80 mm.

2. The method according to claim 1, characterized in that, The tube blank is spun in three or four passes; the same spinning wheel is used for the first and second passes, and the same spinning wheel is used for the third and fourth passes.

3. The method according to claim 2, characterized in that: The parameters of the spinning wheels used in the first-order spinning and second-order spinning are as follows: The infeed angle is 18~30°, the outfeed angle is 10~20°, the forming radius is 15~30 mm, the diameter is 450~550 mm, the thickness is 60~80 mm, the rotation speed is 50~100 rpm, the feed is 0.5~2 mm / rpm, the reduction is 2~6 mm, and the offset between the rotating wheels is 10~15 mm. The parameters of the spinning wheels used in the three-stage and four-stage spinning processes are as follows: The inlet swirl angle is 10~24°, the outlet swirl angle is 10~20°, the forming radius is 15~30 mm, the diameter is 450~550 mm, the thickness is 60~80 mm, the rotation speed is 50~100 rpm, the feed is 0.5~2 mm / rpm, the reduction is 2~6 mm, and the offset between the swirls is 3~8 mm.

4. The method according to claim 3, characterized in that, During the three-stage and four-stage spinning processes, the parameters of the three spinning wheels are as follows: First rotating wheel: inlet angle is 20°, outlet angle is 18°, forming radius is 20 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 60 rpm, feed is 1 mm / rpm, pressing amount is 2 mm, and the offset between rotating wheels is 6 mm. Second rotating wheel: inlet angle is 16°, outlet angle is 18°, forming radius is 20 mm, diameter is 500 mm, thickness is 80 mm, rotation speed is 60 rpm, feed is 1 mm / rpm, pressing amount is 2 mm, and the offset between rotating wheels is 6 mm. The third rotating wheel has an inlet angle of 12°, an outlet angle of 18°, a forming radius of 20 mm, a diameter of 500 mm, a thickness of 80 mm, a rotation speed of 60 rpm, a feed rate of 1 mm / rpm, a pressing amount of 2 mm, and a stagger between the rotating wheels of 6 mm.

5. The method according to claim 1, characterized in that, After each spinning pass, the tube blank is subjected to annealing heat treatment; wherein the annealing heat treatment temperature is 400~550 ℃ and the annealing time is 0.5~8 hours.

6. The method according to claim 2, characterized in that, The thinning amount of the first-order spinning is 30-40%; the thinning amount of the second-order spinning is 30-40%; the thinning amount of the third-order spinning is 20-40%; and the thinning amount of the fourth-order spinning is 10-20%.

7. The method according to claim 1, characterized in that, The spun tube blank is post-processed to obtain the finished tube blank; wherein, the post-processing includes residual stress heat treatment, precision machining and stabilization treatment.

8. The method according to claim 1, characterized in that, Before the actual spinning process, a buffer groove is first spun out in front of and / or behind the pre-set step position on the tube blank to form a step. During the spinning process, each section of the tube blank is spun separately with the step as the dividing line. The starting and ending positions of the spinning of each section of the tube blank are both buffer grooves.

9. A thin-walled, weldless aluminum alloy cylinder with large thickness difference and multiple steps, prepared by the method described in any one of claims 1 to 7; wherein, The difference between the maximum and minimum wall thickness of the aluminum alloy cylinder is 6 to 7 times; preferably, the maximum wall thickness of the aluminum alloy cylinder is greater than 30 mm and the minimum wall thickness is less than 5 mm.

10. The seamless aluminum alloy cylinder according to claim 9, characterized in that, The seamless aluminum alloy cylinder is made of 5-series aluminum alloy, with an inner diameter deviation ≤ ±0.5, roundness deviation ≤ 0.5, straightness deviation ≤ 0.5, yield strength greater than 175 MPa, tensile strength greater than 340 MPa, and elongation greater than 25%.

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