A multi-channel grain refinement device and an extrusion method using the same

Abstract

The present invention relates to the technical field of extrusion devices, specifically to a multi-channel grain refining device and an extrusion method using the device, comprising an inner extrusion cylinder, the bottom surface of which is provided with a cylindrical groove, and the outer side of the inner extrusion cylinder is sleeved with an outer extrusion cylinder; an upper die is arranged inside the cylindrical groove, and a lower die is arranged at the bottom end of the cylindrical groove; a punch is arranged above the upper die, and a forming cavity and a punch outer corner are arranged on the surface of the punch; the beneficial effects are as follows: the multi-channel grain refining device and the extrusion method using the device proposed in the present invention have multi-channel variable diameter angular extrusion channels formed by a combination of grooves distributed on the punch and the die, thereby realizing multi-channel simultaneous variable diameter angular extrusion, with a unique structural design and space saving.

Description

Technical Field

[0001] The invention relates to the technical field of extrusion devices, in particular to a multi-channel grain refining device and an extrusion method using the device. Background Art

[0002] The grain size of metal materials determines the mechanical properties of the materials to a large extent. The finer the grains, the higher the strength of the material, and the plasticity and toughness of the material are also improved.

[0003] In the prior art, Chongqing University's patent "Method and Die for Preparing Magnesium Alloy Profiles by Extrusion and Shaping with Continuous Angular Shearing" (application number: CN200810233106.0, publication number: CN101406906A, publication date: 2009.04.15) discloses a continuous angular extrusion die for magnesium alloys. An extrusion channel with a continuously deflected angle is designed in the die, and the heat-treated magnesium alloy billet is extruded through the die, thereby refining the grains and realizing the preparation of high-strength magnesium alloy profiles; and the equal-diameter and equal-angle extrusion method is changed to the equal-diameter and variable-angle extrusion method, and the grain size of the prepared magnesium alloy profile reaches about 10μm, and the strength of the alloy is significantly improved.

[0004] However, with the development of modern industry, there is an urgent need for isotropic high-strength and toughness alloy profiles to avoid the common problems of ordinary profiles, such as excellent axial performance of extruded profiles but poor longitudinal performance; there is an urgent need to develop isotropic high-strength and toughness extruded profiles, and how to combine ordinary forward extrusion with large plastic deformation technology to give full play to the advantages of large plastic deformation technology in microstructure refinement and obtaining equiaxed crystal structure. Summary of the invention

[0005] The object of the present invention is to provide a multi-channel grain refinement device and an extrusion method using the device, which combines forward extrusion with a large plastic deformation process to directly obtain a material with an ultrafine equiaxed crystal structure, which has excellent mechanical properties and is basically isotropic, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a multi-channel grain refining device, the multi-channel grain refining device comprising:

[0007] An inner extrusion cylinder, the bottom surface of which is provided with a cylindrical groove, and an outer extrusion cylinder is sleeved on the outer side of the inner extrusion cylinder;

[0008] An upper concave die is disposed inside the cylindrical groove, and a lower concave die is disposed at the bottom end of the cylindrical groove; and

[0009] The punch is arranged above the upper die, and the surface of the punch is provided with a forming cavity and a punch outer corner.

[0010] Preferably, the lower concave die is a circular ring plate, the inner ring opening of the lower concave die is one of circular, square, rectangular, and hexagonal, the inner extrusion cylinder is a truncated cone structure, the inner ring opening of the inner extrusion cylinder is a circular opening, and the inner ring diameter of the inner extrusion cylinder is smaller than the diameter of the cylindrical groove.

[0011] Preferably, the outer extrusion cylinder is in a circular tube structure, the inner ring opening of the outer extrusion cylinder is in a truncated cone opening, and the inner ring opening of the outer extrusion cylinder matches the outer ring of the inner extrusion cylinder.

[0012] Preferably, the height of the outer extrusion cylinder is equal to that of the inner extrusion cylinder, and reserved holes are provided on the surfaces of the outer extrusion cylinder and the inner extrusion cylinder, and the two groups of reserved holes are penetrated by thermocouples.

[0013] Preferably, a heating ring is provided on the outer ring surface of the outer extrusion cylinder.

[0014] Preferably, the top surface of the punch is a circular surface, and the bottom surface of the punch is integrally formed with a punch spherical surface, the diameter of the punch spherical surface is Φ5 to Φ50 mm, the outer angles of the punch are distributed on the arc surface of the punch spherical surface, the outer angles of the punch correspond to the molding cavity one by one, and the outer angles of the punch and the molding cavity are connected.

[0015] Preferably, there are multiple molding cavities, which are arranged in a circle around the center of the top surface of the punch, and the diameter of the molding cavity is Φ5~Φ20mm. Multiple outer corners of the punch are spirally structured and converge at the center of the bottom surface of the punch, and the spiral angle is 5°~60°.

[0016] Preferably, the diameter of the upper die spherical surface is equal to the diameter of the punch spherical surface, and after the punch and the upper die are closed, an upsetting and mixing extrusion cavity is formed between the punch spherical surface and the upper die spherical surface.

[0017] Preferably, the alloy blank is loaded into the inner ring opening of the inner extrusion cylinder, and an extrusion rod is movably inserted into the inner ring opening of the inner extrusion cylinder, and the extrusion rod is located above the alloy blank.

[0018] An extrusion method for a multi-channel grain refinement device, the extrusion method comprising the following steps:

[0019] After the punch, the upper die and the lower die are placed in the cylindrical groove, the inner extrusion cylinder and the outer extrusion cylinder are molded together, the heating ring is installed after the mold is closed, and the thermocouple is inserted into the reserved holes on the surface of the outer extrusion cylinder and the inner extrusion cylinder;

[0020] Put the alloy billet into the inner ring of the inner extrusion cylinder, and then put the extrusion rod into the inner ring of the inner extrusion cylinder. The press pushes the extrusion rod downward to apply a pre-pressure of 1 to 3 MPa on the extruded material to ensure close contact between the alloy billet and the extrusion rod, the punch, the upper die and the lower die.

[0021] The extrusion die and the alloy billet are heated by a heating ring, and the heating temperature is monitored by a thermocouple. The temperature is heated to the extrusion temperature required by the alloy to ensure the formability of the alloy billet during the extrusion process and improve the effect of grain refinement. The temperature is kept for 5 to 20 minutes to ensure that the alloy billet is heated evenly.

[0022] The press pushes the extrusion rod downward, causing the alloy billet to flow through the forming cavity first and converge in the upsetting mixed extrusion cavity, and then extrude through the upper and lower concave dies to prepare ultrafine equiaxed crystal extrusion profiles of the required size. The extrusion rate is 2 to 10 m / min. During the extrusion process, the die and the alloy billet to be extruded are continuously heated, and the heating is stopped after the extrusion is completed.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The multi-channel grain refinement device and the extrusion method using the device proposed by the present invention have a multi-channel variable diameter angular extrusion channel formed by a combination of grooves distributed on the punch and the die, thereby realizing multi-channel simultaneous variable diameter angular extrusion, having a unique structural design and saving space;

[0025] When the alloy billet passes through the punch and the upper die, the angle of the forming cavity changes, so it will be subjected to great shear force, resulting in a large number of dislocation accumulations and cellular structures inside the material. Under the action of extrusion temperature and shear force, dynamic recrystallization occurs at the dislocation accumulation, and the cellular structure is transformed into a subgrain boundary with a small curvature through the rearrangement of dislocations, thereby achieving grain refinement. In addition, the spiral cavity design at the bottom of the punch means that the outer angle ψ of the die is constantly changing, which is equivalent to several times of variable diameter angular extrusion. Combined with the multi-channel structural design, it greatly increases the flow, flipping and shearing times of the material in the die, thereby further refining the grains and improving the performance of the material;

[0026] The upsetting mixed extrusion cavity formed by the male die and the upper female die has an upsetting effect. Through upsetting, the banded structure produced in the traditional extrusion process is eliminated, and an equiaxed crystal structure can be obtained, making the material isotropic. Then the material is extruded through the upper female die and the lower female die to obtain an ultra-fine equiaxed crystal material.

[0027] The final female die outlet can be of any cross-sectional shape, so that continuous grain refinement can be achieved while directly extruding into ultrafine equiaxed crystal extruded profiles or rods of various cross-sectional shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the present invention;

[0029] Figure 2 It is a schematic diagram of the structure of the punch of the present invention;

[0030] Figure 3 It is a cross-sectional view of the punch structure of the present invention;

[0031] Figure 4 It is a top view of the male mold structure of the present invention;

[0032] Figure 5 It is a cross-sectional view of the upper die structure of the present invention.

[0033] In the figure: ultrafine equiaxed crystal extrusion profile 1, lower die 2, upsetting mixed extrusion cavity 3, thermocouple 4, alloy billet 5, extrusion rod 6, outer extrusion cylinder 7, inner extrusion cylinder 8, cylindrical groove 81, punch 9, forming cavity 91, punch spherical surface 92, punch outer corner 93, upper die 10, upper die spherical surface 101, heating ring 11. DETAILED DESCRIPTION

[0034] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "one", "first", "second", "third", "fourth", "fifth", "sixth" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] For the purpose of simplicity and illustration, the principles of the embodiments are mainly described by reference to examples. In the following description, many specific details are proposed to provide a thorough understanding of the embodiments. However, it is obvious that for those of ordinary skill in the art, these embodiments may not be limited to these specific details in practice. In some instances, known methods and structures are not described in detail to avoid making these embodiments unnecessarily difficult to understand. In addition, all embodiments can be used in combination with each other.

[0038] See also Figures 1 to 5 The present invention provides a technical solution: a multi-channel grain refining device, the multi-channel grain refining device comprises an inner extrusion cylinder 8, a cylindrical groove 81 is provided on the bottom surface of the inner extrusion cylinder 8, an outer extrusion cylinder 7 is sleeved on the outer side of the inner extrusion cylinder 8, the outer extrusion cylinder 7 is a circular tube structure, the inner ring opening of the outer extrusion cylinder 7 is a truncated cone opening, the inner ring opening of the outer extrusion cylinder 7 matches the outer ring of the inner extrusion cylinder 8, the height of the outer extrusion cylinder 7 is equal to the height of the inner extrusion cylinder 8, and the surfaces of the outer extrusion cylinder 7 and the inner extrusion cylinder 8 are both provided with reserved holes, the two groups of reserved holes are penetrated by thermocouples 4, and the outer ring surface of the outer extrusion cylinder 7 is provided with a heating ring 11;

[0039] The upper die 10 is arranged inside the cylindrical groove 81, and the lower die 2 is arranged at the bottom end of the cylindrical groove 81; the final die outlet can be of any cross-sectional shape, so that the continuous grain refinement can be achieved while directly extruding into ultra-fine equiaxed crystal extrusion profiles or rods of various cross-sectional shapes; the lower die 2 is a circular ring plate, and the inner ring opening of the lower die 2 is one of a circular, square, rectangular, and hexagonal shape; the inner extrusion cylinder 8 is a truncated cone structure, and the inner ring opening of the inner extrusion cylinder 8 is a circular opening, and the inner extrusion cylinder 8 is a circular opening. The inner ring diameter of the inner extrusion cylinder 8 is smaller than the diameter of the cylindrical groove 81, the alloy blank 5 is loaded into the inner ring mouth of the inner extrusion cylinder 8, and the inner ring mouth of the inner extrusion cylinder 8 is movably connected with an extrusion rod 6, and the extrusion rod 6 is located above the alloy blank 5; the upsetting mixed extrusion cavity formed after the male die and the upper female die are combined has an upsetting effect, and the banded structure produced in the traditional extrusion process is eliminated through upsetting, and an equiaxed crystal structure can be obtained, making the material isotropic, and then the material is extruded through the upper female die and the lower female die to obtain an ultra-fine equiaxed crystal material;

[0040] The punch 9 is arranged above the upper die 10. The surface of the punch 9 is provided with a molding cavity 91 and a punch outer corner 93. The top surface of the punch 9 is a circular surface. The bottom surface of the punch 9 is integrally formed with a punch spherical surface 92. The diameter of the punch spherical surface 92 is Φ5 to Φ50 mm. The punch outer corner 93 is distributed on the arc surface of the punch spherical surface 92. The punch outer corner 93 corresponds to the molding cavity 91 one by one, and the punch outer corner 93 and the molding cavity 91 are connected. A plurality of molding cavities 91 are provided. The plurality of molding cavities 91 are arranged in a circular shape around the center of the top surface of the punch 9. The diameter of the molding cavity 91 is Φ5 to Φ20 mm. The plurality of punch outer corners 93 are spirally structured and converge at The center of the bottom surface of the punch 9 has a spiral angle of 5° to 60°, and the diameter of the upper die spherical surface 101 is equal to the diameter of the punch spherical surface 92. After the punch 9 and the upper die 10 are closed, the punch spherical surface 92 and the upper die spherical surface 101 form an upsetting mixed extrusion cavity 3; when the alloy billet passes through the punch and the upper die, due to the change in the angle of the forming cavity, it will be subjected to a great shear force, resulting in a large number of dislocation accumulations and cellular structures inside the material. Under the action of extrusion temperature and shear force, dynamic recrystallization occurs at the dislocation accumulation, and the cellular structure is transformed into a subgrain boundary with a small curvature through the rearrangement of dislocations, thereby achieving grain refinement. In addition, the spiral cavity design at the bottom of the punch means that the outer angle ψ of the mold is constantly changing, which is equivalent to performing several times of variable diameter angular extrusion. Combined with the multi-channel structural design, the number of material flows, flips and shears in the mold is greatly increased, thereby further refining the grains and improving the performance of the material.

[0041] An extrusion method for a multi-channel grain refinement device, the extrusion method comprising the following steps:

[0042] After the male die 9, the upper female die 10 and the lower female die 2 are placed in the cylindrical groove 81, the inner extrusion cylinder 8 and the outer extrusion cylinder 7 are molded together, and after the molds are closed, the heating ring 11 is installed, and the thermocouple 4 is inserted into the reserved holes on the surfaces of the outer extrusion cylinder 7 and the inner extrusion cylinder 8;

[0043] Put the alloy billet 5 into the inner ring opening of the inner extrusion cylinder 8, and then put the extrusion rod 6 into the inner ring opening of the inner extrusion cylinder 8. The press pushes the extrusion rod 6 to move downward, and applies a pre-pressure of 1 to 3 MPa on the extruded material to ensure that the alloy billet 5 is in close contact with the extrusion rod 6, the punch 9, the upper die 10 and the lower die 2;

[0044] The extrusion die and the alloy blank 5 are heated by the heating ring 11, and the heating temperature is monitored by the thermocouple 4. The alloy blank 5 is heated to the extrusion temperature required by the alloy to ensure the formability of the alloy blank 5 during the extrusion process and improve the effect of grain refinement. The alloy blank 5 is kept warm for 5 to 20 minutes to ensure that the alloy blank 5 is heated at a uniform temperature.

[0045] The press pushes the extrusion rod 6 to move downward, causing the alloy billet 5 to first flow through the forming cavity 91 and converge in the upsetting mixed extrusion cavity 3, and then be extruded through the upper die 10 and the lower die 2 to prepare an ultrafine equiaxed crystal extruded profile 1 of the required size. The extrusion rate is 2 to 10 m / min. During the extrusion process, the mold and the alloy billet 5 to be extruded are continuously heated, and the heating is stopped after the extrusion is completed.

[0046] Embodiment 1

[0047] This embodiment is an extrusion method for refining grains of AZ31B magnesium alloy, and the method comprises the following steps:

[0048] (1) After the male die 9, the upper female die 10, and the lower female die 2 are placed in the inner extrusion cylinder 8, the inner extrusion cylinder 8 and the outer extrusion cylinder 7 are molded together, and after the molds are closed, the heating ring 11 is installed, and the thermocouple 4 is inserted into the extrusion cylinder;

[0049] (2) The magnesium alloy billet 5 is placed in the cavity of the inner extrusion cylinder 8, and then the extrusion rod 6 is placed in the inner extrusion cylinder 8. The press pushes the extrusion rod 6 to move downward, and a pre-pressure of 1 MPa is applied to the extruded material to ensure close contact between the magnesium alloy billet 5 and the extrusion rod 6, the punch 9, the upper die 10, and the lower die 2;

[0050] (3) The extrusion die and the magnesium alloy billet 5 are heated by the heating ring 11, and the heating temperature is monitored by the thermocouple 4. The temperature is heated to 300° C. to ensure the formability of the magnesium alloy billet 5 during the extrusion process and to improve the effect of grain refinement. The temperature is kept for 5 minutes to ensure that the magnesium alloy billet 5 is heated evenly.

[0051] (4) The press pushes the extrusion rod 6 to move downward, causing the magnesium alloy billet 5 to first flow through the cavity of the punch 9 and converge in the upsetting mixed extrusion cavity 3, and then be extruded through the upper die 10 and the lower die 2 to prepare the ultrafine equiaxed crystal material 1; the extrusion rate is 8m / min, and the die and the magnesium alloy billet 5 to be extruded are continuously heated during the extrusion process, and the heating is stopped after the extrusion is completed.

[0052] The punch 9 used in this embodiment has 12 molding cavities with the same diameter evenly distributed on it. The punch spherical surface 92 has the same diameter as the upper die spherical surface 101. The spiral angle of the bottom of the punch 9 is 30°, and the aperture of the lower die is a square hole of 15×15 mm. The obtained ultrafine equiaxed crystal material 1 has good surface quality, precise size, uniform, dense and defect-free structure, and its grain size is 680 nm, the tensile strength is ≥342 MPa, and the elongation is ≥17%.

[0053] Embodiment 2

[0054] This embodiment is a method for extruding a ZK60 magnesium alloy to refine grains, the method comprising the following steps:

[0055] (1) After the male die 9, the upper female die 10, and the lower female die 2 are placed in the inner extrusion cylinder 8, the inner extrusion cylinder 8 and the outer extrusion cylinder 7 are molded together, and after the molds are closed, the heating ring 11 is installed, and the thermocouple 4 is inserted into the extrusion cylinder;

[0056] (2) The magnesium alloy blank 5 is placed in the cavity of the inner extrusion cylinder 8, and then the extrusion rod 6 is placed in the inner extrusion cylinder 8. The press pushes the extrusion rod 6 to move downward, and a pre-pressure of 3 MPa is applied to the extruded material to ensure that the magnesium alloy blank 5 is in close contact with the extrusion rod 6, the punch 9, the upper die 10, and the lower die 2;

[0057] (3) The extrusion die and the magnesium alloy billet 5 are heated by the heating ring 11, and the heating temperature is monitored by the thermocouple 4. The temperature is heated to 340° C. to ensure the formability of the magnesium alloy billet 5 during the extrusion process and to improve the effect of grain refinement. The temperature is kept for 8 minutes to ensure that the magnesium alloy billet 5 is heated evenly.

[0058] (4) The press pushes the extrusion rod 6 downward, causing the magnesium alloy billet 5 to first flow through the cavity of the punch 9 and converge in the upsetting mixed extrusion cavity 3, and then be extruded through the upper die 10 and the lower die 2 to prepare the ultrafine equiaxed crystal material 1. The extrusion rate is 5 m / min, and the die and the magnesium alloy billet 5 to be extruded are continuously heated during the extrusion process, and the heating is stopped after the extrusion is completed.

[0059] The punch 9 used in this embodiment has 6 molding cavities with the same diameter evenly distributed on it. The punch spherical surface 92 has the same diameter as the upper die spherical surface 101. The spiral angle of the bottom of the punch 9 is 60°, and the aperture of the lower die is a circular hole of Φ20 mm. The obtained ultrafine equiaxed crystal material 1 has good surface quality, precise size, uniform, dense and defect-free structure, and its grain size is 355 nm, the tensile strength is ≥360 MPa, and the elongation is ≥20%.

[0060] Embodiment 3

[0061] This embodiment is a method for extruding a ZM5 magnesium alloy to refine grains, the method comprising the following steps:

[0062] (1) After the male die 9, the upper female die 10, and the lower female die 2 are placed in the inner extrusion cylinder 8, the inner extrusion cylinder 8 and the outer extrusion cylinder 7 are molded together, and after the molds are closed, the heating ring 11 is installed, and the thermocouple 4 is inserted into the extrusion cylinder;

[0063] (2) The magnesium alloy billet 5 is placed in the cavity of the inner extrusion cylinder 8, and then the extrusion rod 6 is placed in the inner extrusion cylinder 8. The press pushes the extrusion rod 6 downward to apply a pre-pressure of 2 MPa on the extruded material to ensure that the magnesium alloy billet 5 is in close contact with the extrusion rod 6, the punch 9, the upper die 10, and the lower die 2;

[0064] (3) The extrusion die and the magnesium alloy billet 5 are heated by the heating ring 11, and the heating temperature is monitored by the thermocouple 4. The temperature is heated to 360° C. to ensure the formability of the magnesium alloy billet 5 during the extrusion process and to improve the effect of grain refinement. The temperature is kept for 5 minutes to ensure that the magnesium alloy billet 5 is heated evenly.

[0065] (4) The press pushes the extrusion rod 6 downward, causing the magnesium alloy billet 5 to first flow through the cavity of the punch 9 and converge in the upsetting mixed extrusion cavity 3, and then be extruded through the upper die 10 and the lower die 2 to prepare the ultrafine equiaxed crystal material 1. The extrusion rate is 3 m / min, and the die and the magnesium alloy billet 5 to be extruded are continuously heated during the extrusion process, and the heating is stopped after the extrusion is completed.

[0066] The punch 9 used in this embodiment has 8 molding cavities with the same diameter evenly distributed on it. The diameters of the punch spherical surface 92 and the upper die spherical surface 101 are Φ30mm. The spiral angle of the bottom of the punch 9 is 45°, and the aperture of the lower die is a rectangular hole of 10×4mm. The obtained ultrafine equiaxed crystal material 1 has good surface quality, precise size, uniform, dense and defect-free structure, and its grain size is 320nm, the tensile strength is ≥340MPa, and the elongation is ≥16%.

[0067] Embodiment 4

[0068] This embodiment is an extrusion method for refining grains of MB25 magnesium alloy, and the method comprises the following steps:

[0069] (1) After the male die 9, the upper female die 10, and the lower female die 2 are placed in the inner extrusion cylinder 8, the inner extrusion cylinder 8 and the outer extrusion cylinder 7 are molded together, and after the molds are closed, the heating ring 11 is installed, and the thermocouple 4 is inserted into the extrusion cylinder;

[0070] (2) The magnesium alloy blank 5 is placed in the cavity of the inner extrusion cylinder 8, and then the extrusion rod 6 is placed in the inner extrusion cylinder 8. The press pushes the extrusion rod 6 to move downward, and a pre-pressure of 5 MPa is applied to the extruded material to ensure that the magnesium alloy blank 5 is in close contact with the extrusion rod 6, the punch 9, the upper die 10, and the lower die 2;

[0071] (3) The extrusion die and the magnesium alloy billet 5 are heated by the heating ring 11, and the heating temperature is monitored by the thermocouple 4. The temperature is heated to 360° C. to ensure the formability of the magnesium alloy billet 5 during the extrusion process and to improve the effect of grain refinement. The temperature is kept for 10 minutes to ensure that the magnesium alloy billet 5 is heated evenly.

[0072] (4) The press pushes the extrusion rod 6 downward, causing the magnesium alloy billet 5 to first flow through the cavity of the punch 9 and converge in the upsetting mixed extrusion cavity 3, and then be extruded through the upper die 10 and the lower die 2 to prepare the ultrafine equiaxed crystal material 1. The extrusion rate is 3.5 m / min, and the die and the magnesium alloy billet 5 to be extruded are continuously heated during the extrusion process, and the heating is stopped after the extrusion is completed.

[0073] The punch 9 used in this embodiment has 12 molding cavities with the same diameter evenly distributed on it. The punch spherical surface 92 has the same diameter as the upper die spherical surface 101. The spiral angle of the bottom of the punch 9 is 45°, and the aperture of the lower die is a circular hole of Φ40mm. The obtained ultrafine equiaxed crystal material 1 has good surface quality, precise size, uniform, dense and defect-free structure, and its grain size is 335nm, the tensile strength is ≥380MPa, and the elongation is ≥22%.

[0074] Embodiment 5

[0075] This embodiment is a method for extruding a Mg-8Gd-2Y-1Zn magnesium alloy to refine grains, the method comprising the following steps:

[0076] (1) After the male die 9, the upper female die 10, and the lower female die 2 are placed in the inner extrusion cylinder 8, the inner extrusion cylinder 8 and the outer extrusion cylinder 7 are molded together, and after the molds are closed, the heating ring 11 is installed, and the thermocouple 4 is inserted into the extrusion cylinder;

[0077] (2) The magnesium alloy blank 5 is placed in the cavity of the inner extrusion cylinder 8, and then the extrusion rod 6 is placed in the inner extrusion cylinder 8. The press pushes the extrusion rod 6 to move downward, and a pre-pressure of 5 MPa is applied to the extruded material to ensure that the magnesium alloy blank 5 is in close contact with the extrusion rod 6, the punch 9, the upper die 10, and the lower die 2;

[0078] (3) The extrusion die and the magnesium alloy billet 5 are heated by the heating ring 11, and the heating temperature is monitored by the thermocouple 4. The temperature is heated to 400° C. to ensure the formability of the magnesium alloy billet 5 during the extrusion process and to improve the effect of grain refinement. The temperature is kept for 8 minutes to ensure that the magnesium alloy billet 5 is heated evenly.

[0079] (4) The press pushes the extrusion rod 6 downward, causing the magnesium alloy billet 5 to first flow through the cavity of the punch 9 and converge in the upsetting mixed extrusion cavity 3, and then be extruded through the upper die 10 and the lower die 2 to prepare the ultrafine equiaxed crystal material 1. The extrusion rate is 4.5 m / min, and the die and the magnesium alloy billet 5 to be extruded are continuously heated during the extrusion process, and the heating is stopped after the extrusion is completed.

[0080] The punch 9 used in this embodiment is evenly distributed with 20 forming cavities of the same diameter. The punch spherical surface 92 has the same diameter as the upper die spherical surface 101. The spiral angle of the bottom of the punch 9 is 45°, and the aperture of the lower die is a rectangular hole of 10×40mm. The obtained ultrafine equiaxed crystal material 1 has good surface quality, precise size, uniform, dense and defect-free structure, and its grain size is 330nm, the tensile strength is ≥480MPa, and the elongation is ≥8%.

[0081] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-channel grain refinement device, characterized in that: The multi-channel grain refinement device comprises: An inner extrusion cylinder (8), wherein a cylindrical groove (81) is formed on the bottom surface of the inner extrusion cylinder (8), and an outer extrusion cylinder (7) is sleeved on the outer side of the inner extrusion cylinder (8); An upper concave die (10) is arranged inside the cylindrical groove (81), and a lower concave die (2) is arranged at the bottom end of the cylindrical groove (81); and The punch (9) is arranged above the upper die (10), and the surface of the punch (9) is provided with a molding cavity (91) and a punch outer corner (93); the top surface of the punch (9) is a circular surface, and the bottom surface of the punch (9) is integrally formed with a punch spherical surface (92), and the diameter of the punch spherical surface (92) is F5~F50 mm, the punch outer corners (93) are distributed on the arc surface of the punch spherical surface (92), the punch outer corners (93) and the molding cavity (91) correspond one to one, and the punch outer corners (93) and the molding cavity (91) are connected; a plurality of molding cavities (91) are provided, and the plurality of molding cavities (91) are arranged and distributed in a circular shape around the center of the top surface of the punch (9), and the diameter of the molding cavity (91) is F5-F20 mm; the plurality of punch outer corners (93) are gathered at the center of the bottom surface of the punch (9) in a spiral structure, and the spiral angle is 5°-60°; the diameter of the upper die spherical surface (101) is equal to the diameter of the punch spherical surface (92), and after the punch (9) and the upper die (10) are molded together, an upset mixed extrusion cavity (3) is formed between the punch spherical surface (92) and the upper die spherical surface (101).

2. A multi-channel grain refinement device according to claim 1, characterized in that: The lower concave die (2) is in the form of a circular ring plate, the inner ring opening of the lower concave die (2) is one of a circular, square, rectangular, and hexagonal shape, the inner extrusion cylinder (8) is in the form of a truncated cone, the inner ring opening of the inner extrusion cylinder (8) is in the form of a circular opening, and the inner ring diameter of the inner extrusion cylinder (8) is smaller than the diameter of the cylindrical groove (81).

3. A multi-channel grain refinement device according to claim 2, characterized in that: The outer extrusion cylinder (7) is in the form of a circular tube structure, the inner ring opening of the outer extrusion cylinder (7) is in the form of a truncated cone opening, and the inner ring opening of the outer extrusion cylinder (7) matches the outer ring of the inner extrusion cylinder (8).

4. A multi-channel grain refinement device according to claim 3, characterized in that: The height of the outer extrusion cylinder (7) is equal to the height of the inner extrusion cylinder (8), and reserved holes are provided on the surfaces of the outer extrusion cylinder (7) and the inner extrusion cylinder (8), and the two groups of reserved holes are penetrated by thermocouples (4).

5. A multi-channel grain refinement device according to claim 4, characterized in that: The outer ring surface of the outer extrusion cylinder (7) is provided with a heating ring (11).

6. A multi-channel grain refinement device according to claim 1, characterized in that: The alloy blank (5) is loaded into the inner ring opening of the inner extrusion cylinder (8), and an extrusion rod (6) is movably inserted into the inner ring opening of the inner extrusion cylinder (8), and the extrusion rod (6) is located above the alloy blank (5).

7. An extrusion method of a multi-channel grain refinement device according to any one of claims 1 to 6, characterized in that: The extrusion method comprises the following steps: After the male die (9), the upper female die (10) and the lower female die (2) are placed in the cylindrical groove (81), the inner extrusion cylinder (8) and the outer extrusion cylinder (7) are molded together, and after the molds are molded together, the heating ring (11) is installed, and the thermocouple (4) is inserted into the reserved holes on the surfaces of the outer extrusion cylinder (7) and the inner extrusion cylinder (8); The alloy blank (5) is placed into the inner ring opening of the inner extrusion cylinder (8), and then the extrusion rod (6) is placed into the inner ring opening of the inner extrusion cylinder (8). The press machine pushes the extrusion rod (6) to move downward, and applies a pre-pressure of 1 to 3 MPa on the extruded material to ensure close contact between the alloy blank (5) and the extrusion rod (6), the punch (9), the upper die (10) and the lower die (2); The extrusion die and the alloy billet (5) are heated by a heating ring (11), and the heating temperature is monitored by a thermocouple (4). The alloy billet (5) is heated to the extrusion temperature required by the alloy to ensure the formability of the alloy billet (5) during the extrusion process and to improve the effect of grain refinement. The billet (5) is kept warm for 5 to 20 minutes to ensure that the alloy billet (5) is heated at a uniform temperature. The press pushes the extrusion rod (6) to move downward, causing the alloy billet (5) to first flow through the forming cavity (91) and converge in the upsetting mixed extrusion cavity (3), and then be extruded through the upper concave die (10) and the lower concave die (2) to prepare an ultrafine equiaxed crystal extruded profile (1) of a required size. The extrusion rate is 2 to 10 m / min. During the extrusion process, the die and the alloy billet (5) to be extruded are continuously heated, and the heating is stopped after the extrusion is completed.

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