A device and process for preparing high-performance magnesium alloy pipes by asymmetric internal rotation extrusion

Abstract

The present invention belongs to the technical field of light metal plastic forming, and specifically relates to an asymmetric internal rotation extrusion device and process method for preparing high-performance magnesium alloy pipes. The present invention rotates a rotating cam inside the pipe, so that the c-axis of the pipe grains is deflected along the linear velocity direction of the rotating cam, and the strong base surface texture is weakened. Since the upper and lower linear velocities of the rotating cam are in opposite directions, the c-axis deflection directions of the upper and lower grains of the pipe are opposite, which greatly weakens the texture, reduces anisotropy, and improves the comprehensive mechanical properties of the magnesium alloy pipe. The upper and lower shapes of the inner cavity of the die are different, which leads to different upper and lower flow rates of the material during the extrusion process, forming upper and lower asymmetric shearing, and the grain refinement effect is significant. The rotating cam rotates and moves to the right, so that the shear extrusion space formed by the rotating cam and the inner cavity of the die changes all the time, the end face area and height change all the time, and the upper and lower flow rates of the material are different, which aggravates the upper and lower asymmetric shear deformation and makes the grains more refined.

Description

Technical Field

[0001] The invention belongs to the technical field of light metal plastic forming, and specifically relates to a device and a process method for preparing high-performance magnesium alloy pipes by asymmetric inward rotation extrusion. Background Art

[0002] Magnesium and its alloys are currently the lightest metal structural materials. They have the advantages of low density, high specific strength, high specific stiffness, good damping and shock absorption, good thermal conductivity, good electromagnetic shielding effect, excellent machining performance, stable part size, and easy recycling and processing. Therefore, they occupy an important position in the automotive, 3C, aerospace, military and other fields, and are even known as the "green energy material of the 21st century."

[0003] However, due to its close-packed hexagonal crystal structure, magnesium alloys have only three slip systems at room temperature, which does not meet the principle of coordination of polycrystalline plastic deformation with five slip systems. The macroscopic performance is poor room temperature mechanical properties. In addition, due to the large difference in the critical shear stress of basal and non-basal slip of magnesium alloys, it is not easy to start non-basal slip during low-temperature deformation, which makes the grains in the material have preferential orientation after deformation to form a strong basal texture, which is not conducive to subsequent deformation and limits the application of magnesium alloys in various fields. Grain refinement can significantly improve the mechanical properties of metal materials, and this is also true for magnesium alloys. Severe plastic deformation technology has been proven to be able to effectively refine magnesium alloy grains, such as high pressure torsion (HPT), multi-directional forging (MDF), equal channel angular pressing (ECAP), and rotary extrusion (TE), which can extremely refine the grains and even obtain ultrafine grain structure.

[0004] Therefore, it is very important to invent an effective device and method for weakening the deformation texture and refining the grain of magnesium alloy to expand the application range of magnesium alloy. Summary of the invention

[0005] The present invention aims to solve the above problems and provides a device and a process for preparing high-performance magnesium alloy pipes by asymmetric internal rotation extrusion. Through the device and its processing method, the magnesium alloy billet undergoes continuous and severe asymmetric shear deformation during the processing, thereby achieving grain refinement, weakening texture, reducing anisotropy, improving the room temperature mechanical properties of magnesium alloys, and expanding the application range of magnesium alloys.

[0006] The device of the present invention is realized by the following technical scheme: a device for preparing high-performance magnesium alloy pipes by asymmetric internal rotation extrusion, comprising an external die frame, an asymmetric internal rotation shearing device and a power device, wherein:

[0007] The external mold frame includes a left baffle, a right baffle, a plurality of bolts and heating cotton;

[0008] The asymmetric inward-rotating shearing device comprises an annular punch, a die, a center rod, a rotating cam, a rack, and a positioning frame; the die is horizontally provided with an inner cavity that passes through left and right; the center rod is provided with an internal space, the rotating cam is placed in the internal space of the center rod, the rotating cam is axially horizontal and perpendicular to the center rod, the internal space is connected to the outside world from top to bottom, the internal space protrudes outward on both sides of the axial direction of the rotating cam to form a protrusion, the rotating cam protrudes axially outward and a gear is installed on the protruding part; the internal space of the center rod also includes a pair of long grooves opened in a direction parallel to the axial direction of the center rod, the right ends of the pair of long grooves pass through two protrusions respectively, and the center rod is provided with a left space that passes through the left end of the long groove; an opening is provided at the bottom of the annular punch;

[0009] The power device comprises a horizontal extruder, a pressure motor, an extrusion telescopic chamber, and a horizontally arranged extrusion telescopic pressure head connected to the extrusion telescopic chamber;

[0010] The left and right baffles are installed on the horizontal extruder, the die is fixed between the left and right baffles, the left and right baffles are connected together by multiple bolts, the heating cotton is wrapped around the die, and through holes are opened on the left and right baffles at positions corresponding to the inner cavity of the die; the annular punch is fixed to the extrusion telescopic pressure head, is placed coaxially with the die and can extend into the die from the left end; the center rod extends into the annular punch from the right end and is placed coaxially with the die; the rack is placed horizontally in the long groove in the internal space of the center rod and meshes with the gear on the protruding part of the rotating cam; the positioning frame extends from the opening at the bottom of the annular punch into the space on the left side of the center rod to fix the rack; the space between the die, the annular punch, the center rod and the rotating cam together constitutes the shear extrusion space.

[0011] The extrusion space includes three areas, which are arranged from left to right in sequence, namely, the material placement area I, the asymmetric inward rotation shearing area II and the material discharging area III. The material placement area I places the original magnesium alloy tube, the asymmetric inward rotation shearing area II performs asymmetric shearing up and down, and the rotating cam rotates and moves to the right at the same time, so that the upper and lower shearing end faces change all the time, and the material discharging area III will extrude the magnesium alloy tube in the asymmetric inward rotation shearing area II. When the extrusion telescopic pressure head pushes the annular punch and the center rod to move to the right, the rack is fixed by the positioning frame, and the extended part of the rotating cam in the center rod meshes with the rack and starts to rotate, and the rotation angular velocity is ω. At this time, the upper and lower parts of the material in the die begin to be asymmetric sheared by the asymmetric shape of the channel up and down, and the relative flow rate of the upper and lower materials is different. The rotating cam rotates and moves to the right at the same time, and the die is fixed so that the shearing end faces formed by the upper and lower rotating cam and the inner wall of the die change all the time. The rotating cam rotates in opposite directions with the upper and lower linear velocities, weakening the texture while causing the upper and lower grains to deflect in the opposite direction.

[0012] The device can realize the preparation of high-performance magnesium alloy tubes by asymmetric inward rotation extrusion through a built-in rotating cam.

[0013] Furthermore, the inner space of the center rod for accommodating the rotating cam is in the shape of an arc on both sides of the center rod axis to form a circular track, and the inner wall of the die cavity corresponding to the rotating cam is a wave-shaped structure connected by multiple arcs of different radii.

[0014] When the center rod moves to the right with the annular punch, the rack remains stationary under the fixation of the positioning frame, and the rotating cam rotates counterclockwise under the meshing of the rack. At the beginning, due to the limited rightward movement distance of the center rod and the small rotation angle of the rotating cam, the boundary of the rotating cam cannot extend out of the center rod. At this time, it is mainly affected by the different upper and lower arc radii of the inner cavity of the die for asymmetric shear deformation and extrusion; when the center rod moves a certain distance and the rotating cam rotates to a certain angle, the two sides of the boundary of the rotating cam extend the center rod upward and downward respectively. At this time, in addition to the different upper and lower arc radii of the inner cavity of the die, the asymmetric shear deformation is greatly aggravated by the extension of the center rod by the boundary of the rotating cam. The end face shape of the deformation space is formed by the inner cavity of the die and the rotating cam. The rotation angle of the rotating cam changes with the movement of the central axis, so the end faces of each part of the deformation zone change with the movement of the central rod at this time; when the rotating cam rotates 90°, the inner rotating cam boundary extends the longest distance, the end face height is the smallest, and the asymmetric shear caused by the built-in rotating cam is the most severe; when the rotation angle of the rotating cam exceeds 90°, the extended part of the built-in rotating cam boundary gradually decreases, and the degree of asymmetric shear caused gradually decreases; when the built-in rotating cam rotates a certain angle, its rotation boundary is completely transferred into the central rod, and the degree of asymmetric shear caused by the built-in rotating cam is the smallest, and its state is mirror-symmetrical with the state at the beginning; as the central rod moves to the right, the rotating cam continues to rotate, and the extended part of the rotating cam is mirror-symmetrical with the extended part at 0°~180°, and the movement state is the same, but due to the different boundary arc radii of the rotating cam, the end face shape of the asymmetric shear space formed thereby is different from the end face when it rotates 0°~180°, and the degree of asymmetric shear caused is different.

[0015] Furthermore, the asymmetric inward rotation shear region II is affected by the shape of the inner cavity of the die to form asymmetric shear. This violent plastic deformation can effectively refine the grains. At the same time, the rotating cam rotates and moves to the right, so that the shear space of the asymmetric inward rotation shear region II formed by the die and the rotating cam changes all the time. The end face area and height change all the time. The material flow rates in the deformation area are different up and down, which aggravates the asymmetric shear and greatly refines the grains.

[0016] Furthermore, the built-in rotating cam rotates inside the tube, causing the c-axis of the grain to deflect along the linear velocity direction of the rotating cam, and the strong base surface texture is effectively weakened. At the same time, since the upper and lower linear velocities of the built-in rotating cam are in opposite directions during rotation, the c-axis deflection directions of the upper and lower grains of the tube are opposite, which greatly weakens the texture.

[0017] Furthermore, heating cotton is arranged outside the concave mold; the concave mold is connected to the left and right fixing plates by four bolts.

[0018] Furthermore, the materials of the annular punch, die, center rod, rotating cam, rack and positioning frame are all hot working die steel 4Cr5MoSiV1, wherein the inner diameter, outer diameter, length and height of the annular punch, die, center rod, rotating cam and positioning frame are all different; the surface roughness of the annular punch, die, center rod, rotating cam, rack and positioning frame are all Ra0.16~0.4μm.

[0019] The method for preparing a high-performance magnesium alloy tube by asymmetric internal rotation extrusion of the present invention comprises the following steps:

[0020] S1-1. Use 600-mesh sandpaper to polish the inner and outer surfaces of the magnesium alloy tube to remove oil stains, and then use 800-mesh, 1000-mesh, and 1200-mesh sandpaper to polish in sequence until the surface of the magnesium alloy tube is smooth;

[0021] S1-2, mixing acetone and anhydrous ethanol in a volume ratio of 3:2 in a cleaning tank and stirring evenly to prepare a cleaning solution;

[0022] S1-3, immersing the magnesium alloy tube prepared in step S1-1 into the cleaning solution prepared in step S1-2, placing the cleaning tank on an ultrasonic cleaning machine to ultrasonically clean the magnesium alloy tube for 60 minutes, then taking out the magnesium alloy tube and cleaning it with anhydrous ethanol, and finally drying it with a hair dryer;

[0023] S1-4, applying graphite oil solution to the inner and outer surfaces of the magnesium alloy tube prepared in step S1-3 for use in the next step;

[0024] S2. Preheating of magnesium alloy pipes: Set the heating temperature of the vacuum atmosphere heating furnace to 450°C. After the heating furnace temperature reaches the set temperature, put the magnesium alloy pipes into the heating furnace and keep them warm for 3 hours.

[0025] S3. Lubrication, assembly and preheating of asymmetric internal rotation extrusion forming device:

[0026] S3-1, Lubrication: Apply graphite oil solution to the inner cavity of the die, the inner and outer surfaces of the annular punch, the inner and outer surfaces of the center rod, the outer surface of the rack, the outer surface of the positioning frame and the outer surface of the rotating cam;

[0027] S3-2, Assembly:

[0028] First, the die is connected to the left baffle and the right baffle with bolts, and installed on the horizontal extruder, and the heating cotton is placed around the die; the extrusion telescopic ram is fixed to the annular punch, and the annular punch is extended into the die and placed coaxially with the die; the rack is placed inside the center rod, and then the rotating cam is placed in the corresponding space inside the center rod and meshed with the rack, and then the center rod is extended from the right end into the annular punch and contacts with the extrusion telescopic ram; the positioning frame is connected to the rack and extended from under the die and the center rod and fixed on the horizontal extruder;

[0029] S3-3, preheating: control the heating temperature to 300~500℃, keep it warm for 2~4 hours after reaching the set temperature, and reserve it for later use;

[0030] S4, asymmetric inward rotation extrusion forming: the space between the concave die, the annular punch, the center rod and the rotating cam together constitutes a shearing extrusion space; the shearing extrusion space includes three areas arranged from left to right, namely, a material placement area I, an asymmetric inward rotation shearing area II and a material discharge area III;

[0031] S4-1. Place the magnesium alloy tube on the right side of the annular punch and contact it. Then, the extrusion telescopic pressure head pushes the annular punch, the center rod and the tube to the right into the die. When the tube reaches the material placement area I, it stops. The motor is started to extrude the tube into the shear extrusion space. The center rod moves to the right. At the same time, since the rack is fixed, the rack and the extended part of the rotating cam are engaged, and the rotating cam starts to rotate. Due to the different shapes of the upper and lower inner cavities of the die, asymmetric shearing is formed. The rotating cam rotates and moves to the right, so that the upper and lower shear extrusion spaces change all the time. The end surface area and height of the shear extrusion space change all the time, which aggravates the asymmetric shearing. During the asymmetric internal rotation extrusion forming process, the heating temperature is controlled to be 300~500℃.

[0032] S4-2, the pipe is placed in the placing area I by the press machine, and asymmetric shear deformation is performed in the asymmetric inward rotation shearing area II, and finally the discharge is completed in the discharge area III; asymmetric inward rotation extrusion deformation occurs, so that the grains of each section of the magnesium alloy pipe are refined and the texture is weakened; the annular punch moves to the right to a certain distance, and then the stop button is pressed to complete the asymmetric inward rotation extrusion deformation of the magnesium alloy pipe, and a uniform high-performance magnesium alloy pipe with finer grains is obtained;

[0033] S4-3. Take out the magnesium alloy tube obtained in step S4-2, polish its surface with sandpaper, then clean the magnesium alloy tube with the cleaning solution prepared in step S1-2, finally clean it twice with anhydrous ethanol, and dry it with a hair dryer to obtain a high-performance magnesium alloy tube that can be put into use directly.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The rotating cam rotates inside the tube, causing the c-axis of the tube grain to deflect along the linear velocity direction of the rotating cam, and the strong base surface texture is weakened. Since the upper and lower linear velocities of the rotating cam are in opposite directions, the c-axis of the upper and lower grains of the tube are deflected in opposite directions, which greatly weakens the texture, reduces anisotropy, and improves the comprehensive mechanical properties of the magnesium alloy tube.

[0036] 2. The upper and lower shapes of the inner cavity of the die are different, which leads to different upper and lower flow velocities of the material during the extrusion process, forming upper and lower asymmetric shearing, resulting in severe plastic deformation, significant grain refinement effect, and more uniform structure of the obtained magnesium alloy tube.

[0037] 3. The rotating cam rotates and moves to the right, so that the shear extrusion space formed by the rotating cam and the inner cavity of the die changes all the time, the end surface area and height change all the time, and the material flow rate is different up and down, which aggravates the asymmetric shear deformation up and down, and the plastic deformation is more severe, making the grains finer, and can also effectively weaken the texture and improve the mechanical properties of the magnesium alloy pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of a device for preparing high-performance magnesium alloy tubes by asymmetric internal rotation extrusion in the present invention;

[0039] Figure 2 for Figure 1 Distribution map of the middle deformation area;

[0040] Figure 3 This is the change diagram of the cavity in the deformation area during the extrusion process;

[0041] Figure 4 It is the structural diagram of the annular punch;

[0042] Figure 5 is a structural diagram of a rotating cam;

[0043] Figure 6 This is the structural diagram of the right half of the center rod;

[0044] Figure 7 This is the structural diagram of the left half of the center rod;

[0045] Figure 8 It is the structural diagram of the inner cavity of the die;

[0046] Fig. 9 This is a diagram of the internal and external states of the magnesium alloy tube blank.

[0047] In the figure: 1—base, 2—horizontal extruder, 3—display screen, 4—indicator light, 5—power switch, 6—heating switch, 7—telescopic pressure head switch, 8—emergency brake switch, 9—connecting wires, 10—pressure motor base, 11—pressure motor, 12—pressure motor transmission belt, 13—extrusion telescopic cavity, 14—extrusion telescopic pressure head, 15—annular punch, 16—positioning frame, 17—rack, 18—center rod, 19—left baffle, 20—heating cotton, 21—die, 22—rotating cam, 23—right baffle, 24—bolt, 25—magnesium alloy pipe.

[0048] Ⅰ-loading area; Ⅱ-asymmetric inward shearing area Ⅱ; Ⅲ-discharging area. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0050] A device for preparing high-performance magnesium alloy pipes by asymmetric internal rotation extrusion, comprising an external die frame, an asymmetric internal rotation shearing device and a power device, wherein:

[0051] The external mold frame includes a left baffle 19, a right baffle 23, a plurality of bolts 24 and a heating cotton 20;

[0052] The asymmetric internal rotation shearing device includes an annular punch 15, a die 21, a center rod 18, a rotating cam 22, a rack 17, and a positioning frame 16; the die 21 is horizontally opened with an inner cavity that passes through left and right; the center rod 18 is opened with an internal space, and the rotating cam 22 is placed in the internal space of the center rod 18, the rotating cam 22 is axially horizontal and perpendicular to the center rod, the internal space is connected to the outside world from top to bottom, and the internal space protrudes outward on both sides of the axial direction of the rotating cam 22 to form a protrusion, the rotating cam 22 protrudes axially outward and a gear is installed on the protruding part; the internal space of the center rod 18 also includes a pair of long grooves opened in a direction parallel to the axial direction of the center rod, the right end of the long groove passes through two protrusions, and the center rod 18 is opened with a left space that passes through the left end of the long groove; the bottom of the annular punch 15 is provided with an opening;

[0053] The power device includes a horizontal extruder 2, a pressure motor 11, an extrusion telescopic chamber 13, and a horizontally arranged extrusion telescopic pressure head 14 connected to the extrusion telescopic chamber 13;

[0054] The left and right baffles are installed on the horizontal extruder 2, and the die 21 is fixed between the left and right baffles, which are connected together by multiple bolts 24. The heating cotton 20 is wrapped around the die 21, and through holes are opened at positions corresponding to the through holes of the die 21 on the left and right baffles; the annular punch 15 is fixed to the extrusion telescopic pressure head 14, is coaxially placed with the die 21 and can extend into the die 21 from the left end; the center rod 18 extends into the annular punch 15 from the right end and is coaxially placed with the die 21; the rack 17 is horizontally placed in the long groove of the internal space of the center rod 18 and meshes with the gear on the protruding part of the rotating cam 22; the positioning frame 16 extends from the opening at the bottom of the annular punch 15 into the space on the left side of the center rod 18 to fix the rack 17; the space between the die 21, the annular punch 15, the center rod 18 and the rotating cam 22 together constitutes the shear extrusion space.

[0055] Furthermore, when the extrusion telescopic ram 14 pushes the annular punch 15 and the center rod 18 to move to the right, the rack 17 is fixed by the positioning frame 16, and the protruding part of the rotating cam 22 in the center rod 18 meshes with the rack 17 and starts to rotate, with an angular velocity of ω. At this time, the upper and lower parts of the material in the die 21 begin to be asymmetrically sheared due to the asymmetric shape of the channel, and the relative flow rates of the upper and lower materials are different. The rotating cam 22 rotates and moves to the right at the same time, and the die 21 is fixed so that the shear end surface formed by the upper and lower rotating cam 22 and the inner wall of the die 21 changes all the time. Due to the rotation of the rotating cam 22, the pipe is sheared in the upper and lower directions, and the shearing in the same direction as the center rod 18 is promoted, and the shearing in the opposite direction to the center rod 18 is suppressed, so that the upper and lower shearing degrees are different, and the strong base surface texture is effectively weakened.

[0056] Furthermore, the inner space of the center rod 18 for accommodating the rotating cam 22 is in the shape of an arc on both sides of the axial direction of the center rod 18 to form a circular track, and the inner cavity of the die 21 and the inner wall corresponding to the rotating cam 22 are in a wave-shaped structure connected by multiple arcs with different radii.

[0057] When the center rod 18 moves to the right with the annular punch 15, the rack 17 remains stationary under the fixation of the positioning frame 16, and the rotating cam 22 rotates counterclockwise under the meshing of the rack 17. At the beginning, due to the limited rightward movement distance of the center rod 18 and the small rotation angle of the rotating cam 22, the boundary of the rotating cam 22 cannot extend out of the center rod 18. At this time, it is mainly affected by the different upper and lower arc radii of the inner cavity of the die 21, and the asymmetric shear deformation and extrusion are mainly caused; when the center rod 18 moves a certain distance, when the rotating cam 22 rotates to a certain angle, the two sides of the boundary of the rotating cam 22 extend the center rod 18 upward and downward respectively. At this time, in addition to the different upper and lower arc radii of the inner cavity of the die 21, the asymmetric shear deformation is greatly aggravated by the extension of the boundary of the rotating cam 22 from the center rod 18. The end face shape of the deformation space is formed by the inner cavity of the die 21 and the rotating cam 22. The rotation angle of the rotating cam 22 changes with the movement of the central axis, so at this time, the end faces of each part of the deformation zone change with the movement of the central rod 18; when the rotating cam 22 rotates 90°, the inner rotating cam 22 has the longest boundary extension distance and the smallest end face height, and the asymmetric shear caused by the built-in rotating cam 22 is the most severe; when the rotation angle of the rotating cam 22 exceeds 90°, the extended part of the boundary of the built-in rotating cam 22 gradually decreases, and the degree of asymmetric shear gradually decreases; when the built-in rotating cam 22 rotates 90°, the extended part of the boundary of the built-in rotating cam 22 gradually decreases, and the degree of asymmetric shear gradually decreases. After the cam 22 rotates a certain angle, its rotation boundary is completely transferred into the center rod 18. At this time, the asymmetric shear degree caused by the built-in rotating cam 22 is minimal, and its state is mirror-symmetrical to the initial state. As the center rod 18 moves to the right, the rotating cam 22 continues to rotate. At this time, the extended portion of the rotating cam 22 is mirror-symmetrical to the extended portion at 0°~180°, and the motion state is the same. However, due to the different boundary arc radii of the rotating cam 22, the end face shape of the asymmetric shear space formed thereby is different from the end face when it rotates 0°~180°, resulting in a different degree of asymmetric shear.

[0058] Furthermore, the extrusion space includes three areas, namely, a loading area I, an asymmetric inward rotation shearing area II and a discharging area III, which are arranged in sequence from left to right. The loading area I places the original magnesium alloy tube 25, and the symmetric shearing area II performs asymmetric shearing up and down. At the same time, the rotating cam 22 rotates and moves rightward so that the upper and lower shearing end faces change all the time, and the discharging area III extrude the magnesium alloy tube 25 of the asymmetric inward rotation shearing area II. The device can realize the preparation of high-performance magnesium alloy tubes by asymmetric inward rotation extrusion and deformation.

[0059] Furthermore, the asymmetric inward rotation shear region II is affected by the shape of the inner cavity of the die 21 to form asymmetric shear. This drastic plastic deformation can effectively refine the grains. At the same time, the rotating cam 22 rotates and moves to the right, so that the shear space of the asymmetric inward rotation shear region II formed by the die 21 and the rotating cam 22 changes all the time, and the end face area and height change all the time. The material flow rates in the deformation area are different up and down, which aggravates the asymmetric shear and greatly refines the grains.

[0060] Furthermore, the built-in rotating cam 22 rotates inside the magnesium alloy tube 25, causing the c-axis of the grain to deflect along the linear velocity direction of the rotating cam 22, and the strong base surface texture is effectively weakened. At the same time, since the upper and lower linear velocities of the built-in rotating cam 22 are in opposite directions when rotating, the c-axis deflection directions of the upper and lower grains of the magnesium alloy tube 25 are opposite, which greatly weakens the texture.

[0061] Furthermore, heating cotton is arranged outside the concave mold 21; the concave mold 21 is connected to the left and right fixing plates by four bolts.

[0062] Furthermore, the materials of the annular punch 15, the die 21, the center rod 18, the rotating cam 22, the rack 17 and the positioning frame 16 are all hot working die steel 4Cr5MoSiV1, wherein the inner diameter, outer diameter, length and height of the annular punch 15, the die 21, the center rod 18, the rotating cam 22 and the positioning frame 16 are all different; the surface roughness of the annular punch 15, the die 21, the center rod 18, the rotating cam 22, the rack 17 and the positioning frame 16 are all Ra0.16~0.4μm.

[0063] The outer diameter of the annular punch 15 is D 1 , inner diameter is D 2 , the length is l 1 , the length of the opening of the annular punch 15 is l 2 Width l 3 ; The length of the rotating cam 22 is l 4 , width is l 5 The width of the protruding rack is l 6 , the outer diameter of the protruding part is D 3 , inner diameter is D 4 The outer circle radii are R 1 and R 2 ; The length of the center rod 18 is l 8 The length of the internal space that accommodates the rotating gear 22 is l 7 , the length of the center rod 18 long slot is l 9The radius of the circular track inside the center rod 18 is R 3 The radius of the protruding portion of the inner space of the center rod 18 is R 4 The radius of the upper inner cavity of the die 21 is R 5 , R 6 , R 7 , the lower radius is R 8 , R 9 and R 10 , the moving distance of the annular punch 18 in the die 21 is l 10 ; where R 1 ≠R 2 ≠R 3 ≠R 4 ≠R 5 ≠R 6 ≠R 7 ≠R 8 ≠R 9 ≠R 10 , R 3 >R 2 >R 1 , D 1 ≠D 2 ≠D 3 ≠D 4 , l 1 ≠ l 2 ≠ l 3 ≠ l 4 ≠ l 5 ≠ l 6 ≠ l 7 ≠ l 8 ≠ l 9 ≠ l 10 .

[0064] In this specific embodiment, before asymmetric inward extrusion is performed to prepare a high-performance magnesium alloy tube, the materials and chemical reagents required for the preparation process are first selected:

[0065] 1. Magnesium alloy pipe 25: The material of the pipe is AZ31, containing 96% magnesium, 3% aluminum and 1% zinc;

[0066] 2. Sandpaper, solid;

[0067] 3. Graphite oil solution, viscous liquid;

[0068] 4. Anhydrous ethanol, liquid, purity 99.5%;

[0069] 5. Acetone, liquid, purity 99%.

[0070] A method for preparing a high-performance magnesium alloy tube using the asymmetric inward rotation extrusion device comprises the following steps:

[0071] S1. Pretreatment of magnesium alloy tube 25:

[0072] S1-1, grinding the surface of the magnesium alloy tube 25 with 600-mesh sandpaper to remove oil stains, and then grinding with 800-mesh, 1000-mesh, and 1200-mesh sandpaper in sequence until the surface of the magnesium alloy tube 25 is smooth;

[0073] S1-2, mixing acetone and anhydrous ethanol in a volume ratio of 3:2 in a cleaning tank and stirring evenly to prepare a cleaning solution;

[0074] S1-3, immersing the magnesium alloy tube 25 prepared in step S1-1 into the cleaning solution prepared in step S1-2, placing the cleaning tank on an ultrasonic cleaning machine to ultrasonically clean the magnesium alloy tube 25 for 60 minutes, then taking out the magnesium alloy tube 25 and cleaning it with anhydrous ethanol, and finally drying it with a hair dryer;

[0075] S1-4, applying graphite oil solution to the surface of the magnesium alloy tube 25 prepared in step S1-3 for use in the next step;

[0076] S2. Preheating the magnesium alloy tube 25: setting the heating temperature of the vacuum atmosphere heating furnace to 450° C., after the heating furnace temperature reaches the set temperature, placing the magnesium alloy tube 25 into the heating furnace and keeping it warm for 3 hours;

[0077] S3. Lubrication, assembly and preheating of asymmetric internal rotation extrusion forming device:

[0078] S3-1, lubrication: apply graphite oil solution to the inner and outer surfaces of the annular punch 15, the inner cavity of the die 21, the inner and outer surfaces of the center rod 18, the outer surface of the rotating cam 22, and the surface of the rack 17;

[0079] S3-2, Assembly:

[0080] First, the die 21 is connected to the left baffle 19 and the right baffle 23 by bolts 24, and fixed to the horizontal extruder 2, the annular punch 15 is fixed to the extrusion telescopic ram 14, the rotating cam 22 is assembled into the center rod 18, and at the same time, the right end of the rack 17 is extended into the internal space of the center rod 18, the center rod 18 is extended from the right end of the annular punch 15 and extended to the leftmost end, the left end of the rack 17 is fixed to the positioning frame 16, and the positioning frame 16 is extended from the internal space of the center rod 18 and the annular punch 15 and fixed to the horizontal extruder 2, the original magnesium alloy tube 25 is inserted from the right end of the center rod 18, and the magnesium alloy tube 25 is in contact with the die 21, the annular punch 15 is placed coaxially with the die 21, and the heating cotton 20 is surrounded around the die 21.

[0081] S3-3, preheating: operate the heating switch 6 to control the temperature of the heating cotton 20 to 300-500°C, and keep it warm for 2-4 hours after reaching the set temperature, and reserve it for use in the next step;

[0082] S4, asymmetric inward rotation extrusion forming: the female die 21, the center rod 18, the rotating cam 22, and the annular punch 15 are connected together to form an asymmetric shearing extrusion space; the torsional extrusion space includes three areas arranged from left to right, namely, the material placement area I, the asymmetric inward rotation shearing area II, and the material discharging area III;

[0083] S4-1. Push the annular punch 15 to the right so that the magnesium alloy tube 25 is placed in the loading area I, and then continue to operate the annular punch 15 to push the right at a speed of v; during the extrusion process, due to the different upper and lower shapes of the inner cavity of the die 21, the magnesium alloy tube 25 undergoes asymmetric shear deformation up and down; at the same time, the center rod 18 moves to the right driven by the annular punch 15, and the rotating cam 22 moves to the right driven by the center rod 18. Since the rack 17 is fixed by the positioning frame 16 and does not move, the rotating cam rotates under the meshing of the rack 17 and the protruding part of the rotating cam 22, and the rotating cam rotates at an angular velocity of ω. The rotation of the rotating cam 22 and the rightward movement of the rotating cam 22 driven by the center rod 18 cause the asymmetric shear space to change at all times, aggravating the asymmetric shear and making the grains more refined; due to the rotation of the rotating cam 22, the tube has reverse shearing action on the top and bottom, and the c-axis of the grain of the magnesium alloy tube 25 deflects along the linear velocity direction of the rotating cam 22, and the shearing in the same direction as the movement of the center rod 18 is promoted, and the shearing in the opposite direction to the center rod 18 is suppressed, so that the deflection degree of the upper and lower grains of the magnesium alloy tube 25 is different, and the strong base surface texture is effectively weakened. During the asymmetric internal rotation extrusion forming process, the temperature of the heating switch 6 is controlled to be 300~500℃;

[0084] S4-2, the press machine controls the pipe to undergo asymmetric shearing and extrusion deformation in the asymmetric inward rotation shearing area II, and finally discharges the pipe in the discharge area III. The asymmetric shearing and extrusion deformation occurs, so that the grains of each section of the magnesium alloy pipe are refined; wait for the annular punch 15 to move a certain distance, and then press the stop button to complete the deformation process of the pipe into a thin-walled pipe.

[0085] S4-3. Take out the magnesium alloy tube 25 obtained in step S4-2, polish its surface with sandpaper, then clean the magnesium alloy tube 25 with the cleaning solution prepared in step S1-2, finally clean it twice with anhydrous ethanol, and dry it with a hair dryer to obtain a high-performance magnesium alloy tube that can be directly put into use. Specific embodiments

[0086] A process for preparing high-performance magnesium alloy tubes by asymmetric internal rotation extrusion, comprising the following steps:

[0087] (1) Install the external die frame and asymmetric internal rotation shearing device on the horizontal hydraulic extruder. Install them firmly, ensure the positions and connections of each part are correct, and operate in sequence;

[0088] (2) The inner and outer surfaces of the AZ31 magnesium alloy tube blank were polished with 600-grit sandpaper to remove oil stains, and then polished with 1000, 1200, and 2500-grit sandpaper in sequence to ensure that the surface was clean and smooth; the polished magnesium alloy block blank was placed in a mixture of acetone and anhydrous ethanol in a volume ratio of 3:2 for ultrasonic cleaning for 30 minutes, and then cleaned with alcohol and dried with a hair dryer;

[0089] (3) Start the vacuum atmosphere heating furnace to preheat the magnesium alloy tube billet, the preset temperature is 400°C, and when the preset temperature is reached, continue to place the magnesium alloy block billet in the heating furnace for 3 hours;

[0090] (4) Turn on the heating device to heat the asymmetric inward shearing area. The heating temperature is preset to 400°C. After reaching the preset temperature, continue to keep the temperature for 3 hours;

[0091] (5) Apply high-temperature graphite oil solution on the surface of the magnesium alloy block tube blank for lubrication, and start the motor to place the preheated magnesium alloy tube blank in the material placement area I using the annular punch. In the present invention, the annular punch 15, the die 21, the center rod 18, the rotating cam 22, the rack 17, and the positioning frame 16 are all made of hot-working die steel 4Cr5MoSiV1, and the surface roughness of the annular punch 15, the die 21, the center rod 18, the rotating cam 22, the rack 17, and the positioning frame 16 are all Ra0.3μm.

[0092] (6) Turn on the motor, and the annular punch 15 moves to the right under the action of the pressure motor 11 at a speed of vThe speed is about 200mm / min. During the extrusion process, due to the different shapes of the inner cavity of the die 21, the magnesium alloy tube 25 undergoes asymmetric shear deformation. At the same time, the center rod 18 moves to the right under the drive of the annular punch 15, and the rotating cam 22 moves to the right under the drive of the center rod 18. Since the rack 17 is fixed by the positioning frame 16, the rotating cam rotates under the meshing of the rack 17 and the protruding part of the rotating cam 22, and the rotating cam rotates with an angular velocity of about 40r / min. The rotation of the rotating cam 22 and the rightward movement of the rotating cam 22 driven by the center rod 18 cause the asymmetric internal rotation shear space to change all the time, exacerbating the asymmetric shear. Due to the rotation of the rotating cam 22, the tube undergoes reverse shearing up and down, and the shearing in the same direction as the center rod 18 is promoted, and the shearing in the opposite direction to the center rod 18 is suppressed, so that the shearing degree is different up and down, and the strong base surface texture is effectively weakened.

[0093] (7) After the annular punch 15 has moved to a certain extent, the stop button is pressed to complete the deformation process of the tube into a thin-walled tube. The heating switch is turned off and the annular punch 15 is withdrawn.

[0094] (8) The magnesium alloy tube 25 is taken out, and its surface is polished with sandpaper. Then, it is placed in a mixture of acetone and anhydrous ethanol in a volume ratio of 3:2 for ultrasonic cleaning. Finally, it is cleaned with alcohol and dried with cold air from a hair dryer.

[0095] Conclusion: By inventing an asymmetric internal rotation extrusion device and process method for preparing high-performance magnesium alloy tubes, the average grain size of the magnesium alloy billet is greatly reduced compared with conventional magnesium alloys, from the original 33μm to 1.52 μm, and the upper and lower textures are asymmetric weakened. The basal texture is transformed from a strong basal texture to a deflected weak basal texture, and the texture is effectively weakened compared with the initial magnesium alloy tube.

[0096] Materials and chemical reagents used: AZ31 magnesium alloy tube blank, with an outer diameter of d = 100 mm and an inner diameter of d = 60 mm; sandpaper: SiC, 600 mesh, 2 sheets; 1000 mesh, 2 sheets; 1200 mesh, 2 sheets; 2500 mesh, 2 sheets; high temperature graphite oil solution: C, 500 g; anhydrous ethanol: CH 3 CH 2 OH, 1200ml; acetone: C 3 H 6 O, 800ml.

[0097] The principle of obtaining a high-performance magnesium alloy tube through the above steps of the present invention is described in detail below in conjunction with the accompanying drawings:

[0098] Turn on the motor, the annular punch 15 moves to the right under the action of the pressure motor 11, and its speed is v, and the original magnesium alloy tube 25 is pushed into the asymmetric internal rotation shear area II; during the extrusion process, due to the different upper and lower shapes of the inner cavity of the die 21, the magnesium alloy tube 25 undergoes asymmetric shear deformation up and down, asymmetric shear plastic deformation, and the grain structure undergoes severe plastic deformation and grain refinement. At the same time, the center rod 18 moves to the right under the drive of the annular punch 15, and the rotating cam 22 moves to the right under the drive of the center rod 18. Since the rack 17 is fixed by the positioning frame 16, the rotating cam rotates under the meshing of the rack 17 and the protruding part of the rotating cam 22, and the rotating cam rotates at an angular velocity of ω. The rotation of the rotating cam 22 and the rightward movement of the rotating cam 22 driven by the center rod 18 cause the upper and lower asymmetric shear space to change all the time, thereby aggravating the asymmetric shear; due to the rotation of the rotating cam 22, the tube undergoes reverse shearing action up and down, the shearing in the same direction as the movement of the center rod 18 is promoted, and the shearing in the opposite direction to the center rod 18 is suppressed, resulting in different degrees of shearing up and down, effectively weakening the strong base surface texture, reducing anisotropy, improving the performance of the magnesium alloy material, and effectively improving the mechanical properties, thereby obtaining a high-performance magnesium alloy tube.

[0099] The assembly diagram of the asymmetric inward rotation extrusion die is as follows: Figure 1 As shown. During the extrusion process, due to the different upper and lower shapes of the inner cavity of the die 21, the magnesium alloy tube 25 undergoes asymmetric shear deformation and asymmetric shear plastic deformation, and the grain structure undergoes severe plastic deformation and grain refinement. At the same time, the center rod 18 moves to the right driven by the annular punch 15, and the rotating cam 22 moves to the right driven by the center rod 18. Since the rack 17 is fixed by the positioning frame 16 and does not move, the rotating cam rotates under the meshing of the rack 17 and the protruding part of the rotating cam 22, and the rotation angular velocity is ω. The deformation area is composed of the annular punch 15, the die 21 and the rotating cam 22, as shown Figure 2 As shown in the figure, there are three areas, namely, the material loading area I, the asymmetric inward shearing area II and the material discharging area III, which are arranged from left to right. Figure 3 As shown, during the extrusion process, the movement speed of the annular punch 15 and the center rod 18 is v, and the movement direction is shown in the figure; the angular velocity of the rotating cam 22 is ω, and the rotation direction is shown in the figure; as the center rod 18 moves to the right, the rotating cam 22 rotates, and from top to bottom are the cross-sectional views of the deformation zones of the rotating cam 22 rotating 0°, 45°, 90°, 120° and 180°, respectively, x 1 、x 2 、x 3 、x 4 and x 5 are the distances between the die 21 and the left end face of the center rod 18 when the rotating cam 22 rotates 0°, 45°, 90°, 120° and 180°, respectively. 1 、x2 、x 3 、x 4 and x 5 The difference is the moving distance of the center rod 18 when the rotating cam 22 rotates the corresponding angle. Figure 4 FIG. 1 is a structural diagram of the annular punch 15, and shows the relative movement space of the reserved positioning frame 16 inside the annular punch 15, the length of which is l 2 . Figure 6 The right half of the center rod 18 is a structural diagram showing the rack 17 in the center rod 18. The length of the rack 17 is l 9 . Figure 7 It is a structural diagram of the left half of the center rod 18, and the opening thereon is used for arranging the positioning clamp and the rack. Fig. 9 During the movement, the blank diagram of the magnesium alloy tube is shown when the center rod 18 moves different distances and the rotating cam 22 rotates different angles. A, B, C, D and E are blank diagrams when the rotating cam 22 rotates 0°, 45°, 90°, 120° and 180° respectively. With the rotation and movement of the rotating cam 22, the asymmetric shear space changes all the time, and the shear end face also changes all the time. The rotating cam 22 rotates clockwise, so that the c-axis of the tube grain deflects along the linear velocity direction of the rotating cam 22. Since the rotating linear velocity of the rotating cam 22 is opposite to that of the rotating cam 22, the forces acting on both sides of the tube are opposite, so the deflection degree of the grains on both sides is quite different. The shear in the same direction as the movement of the center rod 18 is promoted, and the shear in the opposite direction to the center rod 18 is suppressed. Therefore, the grain deflection degree on the side in the same direction as the movement of the center rod 18 is greater, and the grain deflection degree on the side in the opposite direction to the movement of the center rod 18 is smaller, and the weakening effect of the texture is more obvious.

[0100] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A device for preparing high-performance magnesium alloy pipes by asymmetric internal rotation extrusion, It is characterized in that It includes an external die frame, an asymmetric internal rotating shearing device and a power device, wherein: The external mold frame comprises a left baffle (19), a right baffle (23), a plurality of bolts (24) and heating cotton (20); The asymmetric internal rotation shearing device comprises an annular punch (15), a die (21), a center rod (18), a rotating cam (22), a rack (17), and a positioning frame (16); the die (21) is horizontally provided with an inner cavity which passes through the center rod (18) and has different shapes at the top and bottom; the center rod (18) is provided with an internal space, the rotating cam (22) is arranged in the internal space of the center rod (18), the axial direction of the rotating cam (22) is horizontal and perpendicular to the axial direction of the center rod (18), the internal space is connected to the outside world at the top and bottom, the internal space protrudes outwards on both sides of the axial direction of the rotating cam (22) to form a protrusion, the rotating cam (22) protrudes outwards axially and a gear is installed on the protruding part; the internal space of the center rod (18) also includes a pair of long grooves which are opened in a direction parallel to the axial direction of the center rod (18), the right ends of the pair of long grooves respectively pass through the two protrusions, and the center rod (18) is provided with a left space which passes through the left end of the long groove; the bottom of the annular punch (15) is provided with an opening; The power device comprises a horizontal extruder (2), a press motor (11), an extrusion telescopic chamber (13), and a horizontally arranged extrusion telescopic pressure head (14) connected to the extrusion telescopic chamber (13); The left and right baffles are installed on the horizontal extruder (2), the die (21) is fixed between the left and right baffles, the left and right baffles are connected together by a plurality of bolts (24), the heating cotton (20) is wrapped around the die (21), and through holes are opened at positions corresponding to the inner cavity of the die (21) on the left and right baffles; the annular punch (15) is fixed to the extrusion telescopic pressure head (14), is coaxially placed with the die (21) and can extend into the die (21) from the left end; the center rod (18) is extended from the right end The end of the annular punch (15) extends into the annular punch (15) and is placed coaxially with the die (21); the rack (17) is placed horizontally in the long groove in the inner space of the center rod (18) and meshes with the gear on the protruding part of the rotating cam (22); the positioning frame (16) extends from the opening at the bottom of the annular punch (15) into the left space of the center rod (18) to fix the rack (17); the space between the die (21), the annular punch (15), the center rod (18) and the rotating cam (22) together constitutes a shearing and extrusion space.

2. The device for preparing high-performance magnesium alloy pipe by asymmetric internal rotation extrusion as claimed in claim 1, It is characterized in that The portion of the inner space of the center rod (18) used to accommodate the rotating cam (22) is in the shape of an arc on both sides of the axial direction of the center rod (18) to form a circular track, and the inner cavity of the die (21) and the inner wall corresponding to the rotating cam (22) are in a wavy structure connected by multiple arcs of different radii.

3. The device for preparing high-performance magnesium alloy pipe by asymmetric internal rotation extrusion as claimed in claim 2, It is characterized in that The outer diameter of the annular punch (15) is D 1 , inner diameter is D 2 , the length is l 1 , the length of the opening of the annular punch (15) is l 2 Width l 3 ; The length of the rotating cam (22) is l 4 , width is l 5 The width of the protruding rack is l 6 , the outer diameter of the protruding part is D 3 , inner diameter is D 4 The outer circle radii are R 1 and R 2 ; The length of the center rod (18) is l 8 The length of the internal space portion accommodating the rotating gear (22) is l 7 , the length of the long slot of the center rod (18) is l 9 The radius of the circular track inside the center rod (18) is R 3 , the radius of the inner protruding part of the center rod (18) is R 4 ; The radii of the inner wall upper part of the inner cavity of the die (21) and the rotating cam (22) are R 5 , R 6 , R 7 , the lower radius is R 8 , R 9 and R 10 , the moving distance of the annular punch (18) in the die (21) is l 10 ; where R 1 ≠R 2 ≠R 3 ≠R 4 ≠R 5 ≠R 6 ≠R 7 ≠R 8 ≠R 9 ≠R 10 , R 3 >R 2 >R 1 , D 1 ≠D 2 ≠D 3 ≠D 4 , l 1 ≠ l 2 ≠ l 3 ≠ l 4 ≠ l 5 ≠ l 6 ≠ l 7 ≠ l 8 ≠ l 9 ≠ l 10 .

4. The device for preparing high-performance magnesium alloy pipe by asymmetric internal rotation extrusion as claimed in claim 3, It is characterized in that The materials of the annular punch (15), the die (21), the center rod (18), the rotating cam (22), the rack (17), and the positioning frame (16) are all hot working die steel 4Cr5MoSiV1; the surface roughness of the annular punch (15), the die (21), the center rod (18), the rotating cam (22), the rack (17), and the positioning frame (16) is Ra0.16~0.4μm.

5. A process for preparing high-performance magnesium alloy tubes by asymmetric internal rotation extrusion, It is characterized in that S1. Pretreatment of magnesium alloy pipes: S1-1, grinding the inner and outer surfaces of the magnesium alloy tube (25) with 600-mesh sandpaper to remove oil stains, and then grinding with 800-mesh, 1000-mesh, and 1200-mesh sandpaper in sequence until the surface of the magnesium alloy tube (25) is smooth; S1-2, mixing acetone and anhydrous ethanol in a volume ratio of 3:2 in a cleaning tank and stirring evenly to prepare a cleaning solution; S1-3, immersing the magnesium alloy tube (25) prepared in step S1-1 into the cleaning solution prepared in step S1-2, placing the cleaning tank on an ultrasonic cleaning machine to ultrasonically clean the magnesium alloy tube (25) for 60 minutes, then taking out the magnesium alloy tube (25) and cleaning it with anhydrous ethanol, and finally drying it with a hair dryer; S1-4, applying a graphite oil solution to the inner and outer surfaces of the magnesium alloy tube (25) prepared in step S1-3, and reserving it for use in the next step; S2, preheating the magnesium alloy tube: setting the heating temperature of the vacuum atmosphere heating furnace to 450° C., after the heating furnace temperature reaches the set temperature, placing the magnesium alloy tube (25) into the heating furnace and keeping the temperature for 3 hours; S3. Lubrication, assembly and preheating of asymmetric internal rotation extrusion forming device: S3-1, lubrication: applying a graphite oil solution to the inner cavity of the die (21), the inner and outer surfaces of the annular punch (15), the inner and outer surfaces of the center rod (18), the outer surface of the rack (17), the outer surface of the positioning frame (16) and the outer surface of the rotating cam (22); S3-2, Assembly: First, the die (21) is connected to the left baffle (19) and the right baffle (23) by bolts (24), and the die is installed on the horizontal extruder (2), and the heating cotton (20) is placed around the die (21); the extrusion telescopic ram (14) is fixed to the annular punch (15), and the annular punch (15) is extended into the die (21) and placed coaxially with the die (21); the rack (17) is placed inside the center rod (18), and then the rotating cam (22) is placed into the corresponding space inside the center rod (18) and meshed with the rack (17), and then the center rod (18) is extended from the right end into the annular punch (15) and contacts the extrusion telescopic ram (14); the positioning frame (16) is connected to the rack (17) and extends from under the die (21) and the center rod (18) and fixed on the horizontal extruder (2); S3-3, preheating: control the heating temperature to 300~500℃, keep it warm for 2~4 hours after reaching the set temperature, and reserve it for later use; S4, asymmetric inward rotation extrusion forming: the space between the concave die (21), the annular punch (15), the center rod (18) and the rotating cam (22) together constitutes a shearing extrusion space; the shearing extrusion space includes three areas arranged in sequence from left to right, namely, a material placement area I, an asymmetric inward rotation shearing area II and a material discharge area III; S4-1. The magnesium alloy tube (25) is placed on the right side of the annular punch (15) and in contact with it. Then, the extrusion telescopic ram (14) pushes the annular punch (15), the center rod (18) and the tube to the right into the die (21). When the tube reaches the material placement area I, it stops. The motor is started to extrude the tube into the shear extrusion space. The center rod (18) moves to the right. At the same time, since the rack (17) is fixed, the rack (17) and the extended part of the rotating cam (22) are engaged, and the rotating cam (22) starts to rotate. Since the upper and lower shapes of the inner cavity of the die (21) are different, asymmetric shearing is formed. The rotating cam (22) rotates and moves to the right, so that the upper and lower shear extrusion spaces change all the time. The end surface area and height of the shear extrusion space change all the time, which intensifies the asymmetric shearing. During the asymmetric internal rotation extrusion forming process, the heating temperature is controlled to be 300~500℃. S4-2, controlling the tube to be placed in the placing area I by means of a press, performing asymmetric shear deformation in the asymmetric inward rotation shearing area II, and finally completing the discharge in the discharge area III; performing asymmetric inward rotation extrusion deformation, so that the grains of each section of the magnesium alloy tube (25) are refined and the texture is weakened; after the annular punch (15) moves to the right to a certain distance, the stop button is pressed to complete the asymmetric inward rotation extrusion deformation of the magnesium alloy tube (25), and obtain a uniform high-performance magnesium alloy tube (25) with finer grains; S4-3. Take out the magnesium alloy tube (25) obtained in step S4-2, polish its surface with sandpaper, then clean the magnesium alloy tube with the cleaning solution prepared in step S1-2, and finally clean it twice with anhydrous ethanol and dry it with a hair dryer to obtain a high-performance magnesium alloy tube that can be directly put into use.

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