Rotary aluminum pipe based on forward extrusion process and method for manufacturing the same

Abstract

This invention relates to the field of aluminum profiles, specifically disclosing a rotating aluminum tube based on a forward extrusion process and its preparation method. The preparation method includes: (1) heating an aluminum alloy ingot and loading it into an extrusion cylinder; (2) using an extrusion rod to extrude the aluminum alloy in the extrusion cylinder into an extrusion die; wherein, the extrusion die includes an upper die and a lower die, the upper die is provided with a die bridge, and a flow divider is formed between adjacent die bridges; the lower die includes a welding chamber and a die hole; (3) under the pressure of the extrusion rod, the die bridge splits the aluminum alloy ingot, forming a metal flow along the flow divider; wherein, along the direction from the upper die to the lower die, the die bridge deflects clockwise or counterclockwise, and the die... The bridge points to the extension line of the mold core, which deviates from the center line of the mold core, so that the metal flow rotates clockwise or counterclockwise during the flow process; (4) Under the pressure of the extrusion rod, the metal flow from the diversion hole enters the welding chamber, and the multiple metal flows flowing out through multiple diversion holes are re-welded in the welding chamber; (5) Under the pressure of the extrusion rod, the re-welded metal flow flows into the working zone formed between the mold core and the mold hole, and a rough blank is formed; (6) The rough blank is quenched and aged to obtain a rotating aluminum tube. Implementing this invention can improve the mechanical properties of the aluminum tube.

Description

Technical Field

[0001] This invention relates to the field of aluminum profiles, and more particularly to a rotating aluminum tube based on a forward extrusion process and its preparation method. Background Technology

[0002] Currently, aluminum alloy tubes on the market are mainly divided into seamless tubes and ordinary tubes. Seamless tubes have superior performance, but require expensive reverse extrusion equipment, resulting in high manufacturing costs. Ordinary tubes, while cheaper, are formed using a forward extrusion + flow-dividing combination die, inevitably leaving weld lines on the tube wall. The microstructure around these weld lines is uneven, with coarse grains, becoming stress concentration areas. Moreover, since the weld line is directly opposite the center, the stress on the outer wall acts directly perpendicularly on the weld line, making it extremely prone to cracking in corrosive or high-pressure environments, thus becoming the weakest link in the entire tube.

[0003] On the other hand, for pipes with larger cross-sectional areas, in order to optimize the flow rate of the extruded metal, more die bridges are often introduced to form more flow dividers, so as to optimize the uniformity of metal flow and improve the extrusion quality. Therefore, the extrusion die of larger aluminum alloy pipes generally needs to be set with 6 to 8 die bridges, which also makes the pipe have 6 to 8 welding lines, which can easily cause defects during use. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a rotary aluminum tube based on a forward extrusion process and its preparation method, which has low manufacturing cost, fewer weld lines in the finished product, and excellent mechanical properties, pressure resistance, and corrosion resistance.

[0005] To address the aforementioned problems, this invention discloses a method for preparing a rotating aluminum tube based on a forward extrusion process, comprising:

[0006] (1) Heat the aluminum alloy ingot and load it into the extrusion cylinder;

[0007] (2) An aluminum alloy in an extrusion cylinder is extruded into an extrusion die using an extrusion rod; wherein the extrusion die includes an upper die and a lower die, the upper die is provided with a die bridge, and a flow divider is formed between adjacent die bridges; the lower die includes a welding chamber and a die hole;

[0008] (3) Under the pressure of the extrusion rod, the die bridge splits the aluminum alloy ingot to form a metal flow along the diversion hole; wherein, along the direction from the upper die to the lower die, the die bridge deflects clockwise or counterclockwise, and the extension line of the die bridge to the die core deviates from the center line of the die core, so that the metal flow rotates clockwise or counterclockwise during the flow process;

[0009] (4) Under the pressure of the extrusion rod, the metal flow from the diversion hole enters the welding chamber, and the multiple metal flows flowing out through the multiple diversion holes are re-welded in the welding chamber.

[0010] (5) Under the pressure of the extrusion rod, the re-welded metal flow flows into the working zone formed between the die core and the die hole, and a rough blank is formed;

[0011] (6) Quench and age the billet to obtain a rotating aluminum tube.

[0012] As an improvement to the above technical solution, the temperature of the lower mold is 10-15°C higher than the temperature of the upper mold;

[0013] The temperature of the extrusion cylinder wall is 20-40°C lower than the temperature of the heated aluminum alloy ingot.

[0014] As an improvement to the above technical solution, along the direction from the upper mold to the lower mold, the flow divider includes an inlet flow divider, an intermediate flow divider, and an outlet flow divider; the width of the inlet flow divider is greater than the width of the intermediate flow divider, and the width of the intermediate flow divider is greater than the width of the outlet flow divider.

[0015] As an improvement to the above technical solution, in step (3), the flow velocity of the metal flow at the inlet diversion hole is less than the flow velocity of the metal flow at the intermediate diversion hole, and the flow velocity of the metal flow at the intermediate diversion hole is greater than the flow velocity of the metal flow at the outlet diversion hole.

[0016] As an improvement to the above technical solution, the width of the outlet diversion hole is greater than the width of the inlet diversion hole.

[0017] As an improvement to the above technical solution, the side wall of the welding chamber and the rear wall of the welding chamber have a smooth transition;

[0018] The rear wall of the welding chamber includes at least one inclined section, which is inclined from the side closer to the upper mold to the side closer to the working zone;

[0019] The tilt angle of the inclined section is 10° to 15°.

[0020] As an improvement to the above technical solution, a blocking part is provided on the rear wall of the welding chamber; the width of the blocking part is 1 / 12 to 1 / 8 of the length of the rear wall of the welding chamber; the height of the blocking part is 1 / 15 to 1 / 6 of the length of the side wall of the welding chamber.

[0021] As an improvement to the above technical solution, the sidewall of the blocking part on the side away from the working belt is inclined, and the inclination angle is 60° to 70°.

[0022] As an improvement to the above technical solution, the depth of the welding chamber is 1 / 4 to 2 / 5 of the thickness of the lower mold.

[0023] Accordingly, the present invention also discloses a rotating aluminum tube, which is prepared by the above-described method for preparing rotating aluminum tubes based on a forward extrusion process.

[0024] Implementing this invention has the following beneficial effects:

[0025] In one embodiment of the present invention, a method for preparing a rotating aluminum tube based on a forward extrusion process is employed, using an extrusion die of a specific shape. Specifically, in this embodiment, the die bridge of the extrusion die is slightly curved in the front-to-back direction, forming a shape similar to a fan blade. Furthermore, the die bridge is not perpendicular to the die core and does not point towards the center of the die core. This structure allows the metal flow to rotate clockwise or counterclockwise, perpendicular to its flow direction, under the guidance of the die bridge. Consequently, the weld line of the aluminum tube also exhibits a curved shape, increasing the bonding area of ​​the extruded metal flow in different flow channels, significantly improving the bonding force, optimizing the crystal quality of the weld area, and resulting in a substantial improvement in the mechanical properties, pressure resistance, and corrosion resistance of the extruded aluminum tube. In addition, the preparation method of the present invention features high extrusion speed and low cost. Attached Figure Description

[0026] Figure 1 This is a flowchart of a method for preparing a rotating aluminum tube based on a forward extrusion process in one embodiment of the present invention;

[0027] Figure 2 This is a front view of the extrusion die in one embodiment of the present invention;

[0028] Figure 3 This is a cross-sectional view of an extrusion die according to an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of the side wall, rear wall and blocking part of the welding chamber in one embodiment of the present invention;

[0030] Figure 5 This is a physical image of the aluminum tube prepared in one embodiment of the present invention.

[0031] In the diagram, 1 is the welding line, 100 is the upper mold, 110 is the mold core, 120 is the mold bridge, 130 is the flow divider hole, 131 is the inlet flow divider hole, 132 is the middle flow divider hole, 133 is the outlet flow divider hole, 200 is the lower mold, 210 is the mold hole, 211 is the working zone, 220 is the welding chamber, 221 is the side wall of the welding chamber, 222 is the rear wall of the welding chamber, 223 is the inclined section, 230 is the blocking part, and 231 is the side wall of the blocking part. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0033] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", 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 this application 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 this application.

[0034] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly, for example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0037] See Figure 1 An embodiment of the present invention provides a method for preparing a rotating aluminum tube based on a forward extrusion process, which includes the following steps:

[0038] S1: Heat the aluminum alloy ingot and load it into the extrusion cylinder;

[0039] S2: The aluminum alloy in the extrusion cylinder is extruded into the extrusion die using an extrusion bar;

[0040] S3: Under the pressure of the extrusion rod, the die bridge splits the aluminum alloy ingot, forming a metal flow along the diversion hole;

[0041] S4: Under the pressure of the extrusion rod, the metal flow from the diversion hole enters the welding chamber, and the multiple metal flows flowing out through the multiple diversion holes are re-welded in the welding chamber;

[0042] S5: Under the pressure of the extrusion bar, the re-welded metal flow flows into the working zone formed between the die core and the die hole, forming a rough blank;

[0043] S6: Quench and age the billet to obtain a rotating aluminum tube.

[0044] Among them, see Figure 2 , Figure 3In one embodiment of the present invention, the extrusion die includes an upper die 100 and a lower die 200 fixedly connected. The upper die 100 includes a die bridge 120, a die core 110, and a flow divider hole 130. The die core 110 is disposed inside the upper die 100, and the die bridge 120 is disposed between the die core 110 and the outer wall of the upper die 100. The flow divider hole 130 is formed between the die cores 110. The lower die 200 includes a welding chamber 220 and a die hole 210. The welding chamber 220 is disposed close to the upper die 100, and the die hole 210 is disposed away from the upper die 100. The welding chamber 220 and the die hole 210 are connected. The die core 110 is partially inserted into the die hole 210, and a working zone 211 is formed between the die core 110 and the die hole 210. In this embodiment, the mold bridge 120 deflects clockwise or counterclockwise along the direction from the upper mold 100 to the lower mold 200, and the extension line of the mold bridge 120 pointing towards the mold core 110 deviates from the center line of the mold core 110. The mold bridge 120 in this embodiment deflects clockwise or counterclockwise, meaning it is slightly curved in the front-to-back direction (from the upper mold 100 to the lower mold 200), forming a shape similar to a fan blade. Furthermore, in the direction from the outer wall of the upper mold 100 to the mold core 110, the extension line of the mold bridge 120 deviates from the center line of the mold core 110, meaning the mold bridge 120 is not completely perpendicular to the mold core 110 and does not point towards the center of the mold core 110. This structure allows the metal flow to rotate clockwise or counterclockwise perpendicular to its flow direction under the guidance of the mold bridge 120, thereby causing the weld line of the aluminum tube to also exhibit a curved shape (see...). Figure 5 This means that the bonding area of ​​the metal flow in different diversion holes 130 is increased, the bonding force is greatly improved, the crystal quality of the welding area is optimized, and the mechanical properties, pressure resistance and corrosion resistance of the extruded aluminum tube are greatly improved.

[0045] Specifically, in some embodiments, in step S1, the material of the aluminum alloy ingot can be common aluminum alloys in the art, such as 6063, 6061, 6082, 6101, 7003, and 3203, but is not limited to these. The heating temperature of the aluminum alloy ingot can be determined according to the specific alloy type. For example, when the alloy is 6063 aluminum alloy, the temperature of the aluminum alloy ingot is 510-530°C; when the alloy is 7001 aluminum alloy, the heating temperature is 480-510°C, but is not limited to these.

[0046] Preferably, in some embodiments, the temperature of the heated aluminum alloy ingot minus the extrusion cylinder wall temperature is controlled to be 20–40°C. In this invention, the temperature difference between the aluminum alloy ingot and the extrusion cylinder is small, which is beneficial for uniformizing the temperature of the aluminum alloy ingot cross-section, thereby maintaining the uniformity of the metal flow velocity during extrusion. This reduces flow velocity unevenness caused by extrusion cylinder friction, optimizes weld quality, and improves the mechanical properties, pressure resistance, and corrosion resistance of the aluminum tube.

[0047] Specifically, in some embodiments, in step S3, the extrusion rod contacts the aluminum alloy ingot through the extrusion pad. The extrusion rod forces the die bridge 120 to split the aluminum alloy ingot, forming multiple streams of metal flowing along the diversion hole 130. Furthermore, the specific shape of the die bridge 120 guides the flow in a clockwise or counterclockwise direction.

[0048] Preferably, in some embodiments, the flow divider 130 includes an inlet flow divider 131, an intermediate flow divider 132, and an outlet flow divider 133 arranged sequentially. The flow velocity of the metal stream at the inlet flow divider 131 is lower than that at the intermediate flow divider 132, and the flow velocity of the metal stream at the intermediate flow divider 132 is higher than that at the outlet flow divider 133. Based on this embodiment, the flow velocity uniformity of the metal stream at the outlet of the flow divider 130 is higher, while effectively maintaining the rotation trend, thus improving the welding quality.

[0049] Specifically, in step S4, since the welding chamber 220 is a hollow cavity as a whole and does not have a segmented structure like the mold bridge 120, multiple metal streams are re-welded here.

[0050] Preferably, in some embodiments, the temperature of the lower mold 200 is controlled to be 20-40°C higher than that of the upper mold 100, and the depth of the welding chamber 220 is correspondingly increased. Based on this control, the weld line can be further reduced and shortened, and the crystal quality of the welding area can be improved. It should be noted that although the deflected mold bridge 120 bends the weld line, improves the bonding surface, and optimizes the crystal quality, the deflected mold bridge 120 also increases the flow distance of the metal flow in the diversion hole 130, and the friction distance between the wall and the metal flow also increases, which makes the crystal lattice more prone to distortion and the formation of coarse-grained structures. Therefore, the present invention increases the temperature of the lower mold 200 and deepens the welding chamber 220, which improves the mixing degree of the metal flow in the welding chamber 220, thereby effectively reducing coarse grains and making the weld line thinner and shallower. Preferably, in some embodiments, the depth of the welding chamber 220 (i.e., its depth in the Y direction) is 1 / 4 to 2 / 5 of the thickness of the lower mold 200.

[0051] Specifically, in some implementations, step S6 involves quenching by methods such as air cooling, water cooling, or mist cooling, but is not limited to these methods.

[0052] The structure of the extrusion die is described in detail below. For ease of explanation, please refer to [link / reference]. Figure 2 , Figure 3 A first direction, a second direction, and a third direction are set on the extrusion die, which are mutually orthogonal. The first direction is defined as the left-right direction of the die (i.e., Figure 2 The second direction is defined as the front-to-back direction of the mold (i.e., the X direction). Figure 3The Y-direction is defined, and the side of the upper die 100 is defined as the front, and the side of the lower die 200 is defined as the rear, meaning that during extrusion, the metal flow is from the front to the rear. The third direction is defined as the up-down direction (i.e.,...). Figure 2 , Figure 3 (in the Z direction).

[0053] In this embodiment, the upper die 100 and lower die 200 of the extrusion die are fixedly connected by connecting screws or the like, but are not limited to this. Before the upper die 100 and lower die 200 are fixedly connected, they can also be assembled and positioned by locating pins.

[0054] Specifically, in some embodiments, the cross-section (the cross-section parallel to the XZ plane) of the diversion hole 130 is circular, fan-shaped, waist-shaped, or other irregularly shaped, but is not limited thereto. Preferably, in some embodiments, see [reference needed]. Figure 2 The cross-section of the diversion hole 130 is fan-shaped. This shape of the diversion hole 130 can effectively balance the flow rate of the extruded metal flow, reduce turbulence, and make the extruded metal flow appear as a rotating flow in the die hole 210, further optimizing the mechanical properties, pressure resistance and corrosion resistance of the aluminum tube.

[0055] Specifically, in some embodiments, the number of diversion holes 130 is ≤ 5. Too many diversion holes 130 result in more weld lines in the extruded aluminum tube, leading to a decrease in its mechanical properties, pressure resistance, and corrosion resistance. However, if the number of diversion holes 130 is ≥ 2, firstly, too few diversion holes 130 result in uneven flow rate of the extruded metal, which is detrimental to welding; secondly, too few diversion holes 130 also lead to a decrease in production efficiency. Preferably, in some embodiments, the number of diversion holes 130 is 2 to 4. More preferably, it is 2 to 3.

[0056] Specifically, in some embodiments, the die core 110 is a cylindrical die core 110, a conical die core 110, or a boss-shaped die core 110, but is not limited to these. Preferably, in some embodiments, the die core 110 is a conical die core 110. This shape of the die core 110 can further optimize the flow direction of the extruded metal flow and reduce the width of the weld line; moreover, this shape of the die core 110 can optimize the strength of the extrusion die, further reduce the number of die bridges 120, and thus reduce the number of weld lines in the aluminum tube, further improving the mechanical properties, pressure resistance, and corrosion resistance of the aluminum tube.

[0057] Specifically, in some embodiments, the cross-section of the mold bridge 120 (i.e., the cross-section parallel to the XZ plane) is rectangular, chamfered rectangular, teardrop-shaped, or trapezoidal, but is not limited to these. Preferably, in some embodiments, the cross-section of the mold bridge 120 is trapezoidal, that is, its thickness on the side near the mold core 110 is less than its width on the side near the upper mold 100 body, and the mold bridge 120 has arc-shaped transition portions at both ends near the upper mold 100 body and near the mold core 110. Based on this cross-sectional shape of the mold bridge 120, the flow diversion hole 130 can be wider on the side near the upper mold 100 body, optimizing the rotation of the extruded metal flow and further improving the mechanical properties, pressure resistance, and corrosion resistance of the aluminum tube.

[0058] More specifically, along the direction from the upper mold 100 to the lower mold 200, the diversion orifice 130 includes an inlet diversion orifice 131, an intermediate diversion orifice 132, and an outlet diversion orifice 133; the width of the inlet diversion orifice 131 is greater than the width of the intermediate diversion orifice 132, and the width of the intermediate diversion orifice 132 is greater than the width of the outlet diversion orifice 133. Even though the width of the diversion orifice 130 generally shows a gradual decrease followed by a gradual increase, it should be noted that the width here refers to the width of the diversion orifice 130 in the XZ plane. If the shape of the diversion orifice 130 in this cross-section is circular, the width is the diameter; if the cross-section is fan-shaped, it is its arc length, but it is not limited to this. Specifically, the wider inlet diversion orifice 131 means a thinner die bridge 120 in this area, which reduces extrusion pressure, facilitates splitting the metal flow, and allows metal to flow more easily into the diversion orifice 130, thus improving extrusion efficiency. Conversely, the narrower width of the intermediate diversion orifice 132 increases the flow velocity of the metal and strengthens the rotational tendency; this also means a thicker die bridge 120 in this area, resulting in higher strength. The wider outlet diversion orifice 133 means a smaller distance between different metal flows, which facilitates welding and optimizes the mechanical properties, pressure resistance, and corrosion resistance of the aluminum tube.

[0059] More preferably, in some embodiments, the width of the outlet diversion orifice 133 is greater than the width of the inlet diversion orifice 131. This results in a slower metal flow velocity in the region near the outlet of the diversion orifice 130, optimizing the welding process, resulting in a thinner and shorter weld line, and further optimizing the mechanical properties, pressure resistance, and corrosion resistance of the aluminum tube.

[0060] Specifically, in some embodiments, the thickness of each cross-section (i.e., the cross-section parallel to the XY plane) of the mold bridge 120 in the direction from the upper mold 100 to the lower mold 200 is the same, with only the cross-sectional thickness varying, but this is not limited to this. Preferably, in some embodiments, the thickness of the mold bridge 120 in the direction from the upper mold 100 to the lower mold 200 exhibits a trend of first gradually increasing and then gradually decreasing, i.e., it is spindle-shaped. This structure can strengthen the support of the mold core 110, thereby enabling this embodiment to further reduce the number of mold bridges 120, reduce the number of aluminum tube welding lines, and improve the mechanical properties, pressure resistance, and corrosion resistance of the aluminum tube.

[0061] Specifically, in the direction from the outer wall of the upper die 100 to the die core 110, the conventional die bridge 120 is perpendicular to the die core 110 and points towards the center of the die core 110. However, this invention employs a slightly curved die bridge 120 that does not point towards the center line of the die core 110 to enhance the rotational tendency of the extruded metal flow. This results in the die bridge 120 and the outer wall of the die core 110 forming a certain angle that is not 90°. Preferably, in some embodiments, the die bridge 120 at the outlet of the diversion hole is tangent or approximately tangent to the outer wall of the die core 110, which makes the weld line thinner and less noticeable.

[0062] Specifically, in some embodiments, the number of die bridges 120 is 2 to 5. Increasing the number of die bridges 120, i.e., increasing the number of diversion holes 130, means more weld lines and a deterioration in the mechanical properties of the aluminum tube; conversely, too few die bridges 120 can easily lead to low extrusion efficiency and poor welding. Preferably, the number of die bridges 120 is 3 to 4. It should be noted that the multiple die bridges 120 deflect in the same direction (clockwise or counterclockwise). Furthermore, the multiple die bridges 120 are evenly distributed circumferentially along the die core 110.

[0063] Specifically, in some embodiments, the deflection angle of the die bridge 120 is 15° to 40° (the deflection angle at the outlet relative to the inlet). When the deflection angle is too large, the flow rate of the metal stream in the diversion hole 130 is too slow, which is not only detrimental to improving extrusion efficiency but also to welding. When the deflection angle is too small, it is difficult to effectively form an extruded metal stream with a rotational tendency, and it is difficult to form a curved weld line. Preferably, the deflection angle of the die bridge 120 is 15° to 30°, which can result in higher extrusion efficiency and better mechanical properties of the extruded aluminum tube.

[0064] Specifically, the welding chamber 220 is a cavity structure formed by a recess behind the lower die 200, and its cross-section is circular or butterfly-shaped, but not limited to these. It is preferably circular, which is more conducive to maintaining the rotational trend of the extruded metal flow, increasing the curvature of the weld line, increasing the contact area, and improving the mechanical properties of the aluminum tube.

[0065] Preferably, in some embodiments, the side wall 221 of the welding chamber and the rear wall 222 of the welding chamber form a smooth transition. This structure can reduce extrusion resistance and optimize the welding quality of the welding line.

[0066] Preferably, in some embodiments, the rear wall 222 of the welding chamber includes an inclined section 223 that slopes from the side near the upper die 100 toward the side near the working belt 211. By introducing the inclined section 223, the pressure inside the welding chamber 220 can be increased, optimizing metal welding. At the same time, the flow rate of the extruded metal flow can be increased before entering the working belt 211, thereby generating agitation of the metal flow, improving the uniformity of mixing, and making the weld line thinner and shorter.

[0067] Specifically, in some embodiments, the tilt angle of the tilting segment 223 is 10° to 15°. Figure 4 (α). When the tilt angle is too large, the flow rate is too fast, the flatness of the aluminum tube wall after extrusion decreases, and roughness defects are easily generated. When the tilt angle is too small, the mixing is insufficient, and it is difficult to effectively shorten the weld line.

[0068] Preferably, see Figure 4 In some embodiments, a blocking part 230 is provided on the rear wall 222 of the welding chamber. The blocking part 230 protrudes from the rear wall 222 of the welding chamber in the direction of the upper mold 100. By introducing the blocking part 230, the pressure can be further increased, the stirring effect can be optimized, and the welding line can be made thinner and shorter.

[0069] Specifically, the width of the blocking part 230 (i.e., the width of its cross-section) is 1 / 12 to 1 / 8 of the length of the rear wall 222 of the welding chamber, and the height of the blocking part 230 (i.e., the height of its protrusion toward the upper mold 100) is 1 / 15 to 1 / 6 of the length of the side wall 221 of the welding chamber. By controlling the width and height of the blocking part 230 as described above, the bending degree of the weld line can be increased while optimizing the stirring effect, thereby further improving the mechanical properties of the aluminum tube.

[0070] Preferably, in some embodiments, the sidewall 231 of the blocking portion on the side away from the working belt 211 is inclined, and the inclination angle is 60° to 70°. Figure 4 (β) By setting the above, the weld line can be shortened.

[0071] In summary, the method for preparing rotary aluminum tubes based on forward extrusion according to the above embodiments of the present invention has the following advantages: First, it allows for the production of aluminum tubes using forward extrusion, reducing production costs. Second, the weld lines of the finished product are curved, increasing the weld contact area and improving the mechanical properties, pressure resistance, and corrosion resistance of the aluminum tube. The performance level of the aluminum tube obtained by the present invention is comparable to that of traditional seamless aluminum tubes. Third, the preparation method of the present invention has high production efficiency, with extrusion speeds reaching 15–30 m / min.

[0072] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0073] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a rotary aluminum tube based on a forward extrusion process, characterized in that, include: (1) Heat the aluminum alloy ingot and load it into the extrusion cylinder; (2) An aluminum alloy ingot in an extrusion cylinder is extruded into an extrusion die using an extrusion rod; wherein the extrusion die includes an upper die and a lower die, the upper die is provided with a die bridge, and a flow divider is formed between adjacent die bridges; the lower die includes a welding chamber and a die hole, and the side wall of the welding chamber and the rear wall of the welding chamber are smoothly transitioned; the rear wall of the welding chamber includes at least one inclined section, the inclined section is inclined from the side near the upper die to the side near the working zone, and the inclination angle is 10°~15°; (3) Under the pressure of the extrusion rod, the die bridge splits the aluminum alloy ingot to form a metal flow along the diversion hole; wherein, along the direction from the upper die to the lower die, the die bridge deflects clockwise or counterclockwise, and the extension line of the die bridge pointing to the die core deviates from the center line of the die core, so that the metal flow forms a clockwise or counterclockwise rotation during the flow process; (4) Under the pressure of the extrusion rod, the metal flow from the diversion hole enters the welding chamber, and the multiple metal flows flowing out through the multiple diversion holes are re-welded in the welding chamber; wherein, a blocking part is provided on the rear wall of the welding chamber, the width of the blocking part is 1 / 12 to 1 / 8 of the length of the rear wall of the welding chamber, and the height of the blocking part is 1 / 15 to 1 / 6 of the length of the side wall of the welding chamber; the side wall of the blocking part away from the working zone is inclined, and its inclination angle is 60° to 70°; (5) Under the pressure of the extrusion rod, the re-welded metal flow flows into the working zone formed between the die core and the die hole, and a rough blank is formed; (6) Quench and age the billet to obtain a rotating aluminum tube.

2. The method for preparing a rotary aluminum tube based on a forward extrusion process as described in claim 1, characterized in that, The temperature of the lower mold is 10-15°C higher than the temperature of the upper mold; The temperature of the extrusion cylinder wall is 20-40°C lower than the temperature of the heated aluminum alloy ingot.

3. The method for preparing a rotary aluminum tube based on a forward extrusion process as described in claim 1, characterized in that, Along the direction from the upper mold to the lower mold, the flow divider includes an inlet flow divider, an intermediate flow divider, and an outlet flow divider; the width of the inlet flow divider is greater than the width of the intermediate flow divider, and the width of the intermediate flow divider is greater than the width of the outlet flow divider.

4. The method for preparing a rotary aluminum tube based on a forward extrusion process as described in claim 3, characterized in that, In step (3), the flow velocity of the metal flow at the inlet diversion orifice is less than the flow velocity of the metal flow at the intermediate diversion orifice, and the flow velocity of the metal flow at the intermediate diversion orifice is greater than the flow velocity of the metal flow at the outlet diversion orifice.

5. The method for preparing a rotary aluminum tube based on a forward extrusion process as described in claim 1, characterized in that, The depth of the welding chamber is 1 / 4 to 2 / 5 of the thickness of the lower mold.

6. A rotating aluminum tube, characterized in that, It is prepared by the method for preparing a rotating aluminum tube based on a forward extrusion process as described in any one of claims 1 to 5.

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