Composite extrusion device and method for strengthening and toughening metal materials

Abstract

The present invention belongs to the technical field of metal plastic processing, and specifically relates to a composite extrusion device and method for strengthening and toughening metal materials. It includes a fixed seat and a rotary extrusion die, an inlet and outlet side extrusion die, a piston side extrusion die and a rotary drive mechanism arranged on the fixed seat, wherein the inlet and outlet side extrusion die, the rotary extrusion die and the piston side extrusion die are coaxially connected in sequence, and the rotary extrusion die can rotate, and the interior of the inlet and outlet side extrusion die, the rotary extrusion die and the piston side extrusion die forms an extrusion cavity, the piston side extrusion die provides extrusion power, and the rotary drive mechanism is connected to the rotary extrusion die, and the rotary drive mechanism is used to drive the rotary extrusion die to rotate, thereby realizing rotary extrusion of the metal blank in the extrusion cavity. The present invention is easy to operate and has high processing efficiency. It can effectively refine the grains, improve the strength and plasticity of the material, and thus improve the mechanical properties of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of metal plastic processing, and in particular relates to a composite extrusion device and method for strengthening and toughening metal materials. Background Art

[0002] Severe plastic deformation (SPD), as an emerging plastic deformation method, can introduce large strains during deformation (traditional plastic deformation struggles to achieve true strains greater than 1), effectively thinning metals (to the submicron or nanometer scale) and producing intact, large-scale bulk specimens. By controlling the microstructure during deformation, bulk nanomaterials with both high strength and high plasticity can be obtained. Equal channel angular pressing (ECAP) is the most widely studied severe plastic deformation method.

[0003] While equal-channel angular extrusion (EACC) is an effective method for producing ultrafine-grained materials, existing die structures still suffer from limited plastic deformation capacity and low efficiency in practical applications. During high-pressure torsional extrusion, the material undergoes intense shear deformation at the die corners, which can easily cause the material to deform, crack, or even break along the shear stress direction, ultimately preventing subsequent extrusion passes. Therefore, improving the die's plastic deformation capacity and efficiency is an urgent issue. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a composite extrusion device and method for strengthening and toughening metal materials, so as to solve the problems of limited plastic deformation capacity of the blank and low working efficiency of the mold in the existing mold structure.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a composite extrusion device for strengthening and toughening metal materials, including a fixed seat and a rotary extrusion die, an inlet and outlet side extrusion die, a piston side extrusion die and a rotary drive mechanism arranged on the fixed seat, wherein the inlet and outlet side extrusion die, the rotary extrusion die and the piston side extrusion die are coaxially connected in sequence, and the rotary extrusion die can rotate, an extrusion cavity is formed inside the inlet and outlet side extrusion die, the rotary extrusion die and the piston side extrusion die, the piston side extrusion die provides extrusion power, and the rotary drive mechanism is connected to the rotary extrusion die, and the rotary drive mechanism is used to drive the rotary extrusion die to rotate, thereby realizing rotary extrusion of the metal blank in the extrusion cavity.

[0007] In one possible implementation, the rotary extrusion die includes a rotary extrusion middle cavity and at least one rotary extrusion side cavity provided on the side of the rotary extrusion middle cavity, wherein a servo hydraulically controlled rotary extrusion rod is provided in the rotary extrusion side cavity;

[0008] The piston side extrusion die includes a piston side extrusion middle cavity and at least one piston side extrusion side cavity provided on the side of the piston side extrusion middle cavity, a piston end side extrusion rod controlled by servo hydraulic pressure is provided in the piston side extrusion side cavity; an ejection piston controlled by servo hydraulic pressure is provided in the piston side extrusion middle cavity;

[0009] The inlet and outlet side extrusion die includes an inlet and outlet side extrusion middle cavity and at least one inlet and outlet side extrusion side cavity provided on the side of the inlet and outlet side extrusion middle cavity, and a servo hydraulically controlled inlet and outlet end extrusion rod is provided in the inlet and outlet side extrusion side cavity; an inlet and outlet port is provided at the end of the inlet and outlet side extrusion middle cavity, and the inlet and outlet port is sealed by an inlet and outlet end sealing cover;

[0010] The piston side extrusion middle cavity, the rotary extrusion middle cavity and the inlet and outlet side extrusion middle cavity are of equal diameter and are interconnected to form a middle extrusion cavity.

[0011] In one possible implementation, the rotary extrusion rod, the inlet and outlet extrusion rod and the piston end side extrusion rod have the same structure, all including an extrusion eccentric rod and an extrusion head arranged at the end of the extrusion eccentric rod. The extrusion eccentric rod and the extrusion head are eccentrically arranged, and the end face of the extrusion head is a spatial extrusion curved surface.

[0012] In one possible implementation, a sealing column protrudes axially from the center of the inner end face of the inlet and outlet sealing cover, and the end face of the sealing column is a curved surface. The sealing column extends axially to the position where the curved surface at the end corresponds to the extrusion side cavity on the inlet and outlet side.

[0013] In one possible implementation, an ultrasonic vibrator is installed on the outer side of the inlet and outlet sealing covers to assist in grain refinement of the extruded metal blank.

[0014] In one possible implementation, a process temperature control module for controlling the temperature of the extrusion process is provided on the outside of the rotary extrusion die; the extrusion die on the feeding and discharging side and the extrusion die on the piston side are connected to electrodes for realizing electric field-assisted grain refinement during the extrusion process; and a shock-absorbing floater is provided at the bottom of the fixed seat.

[0015] In one possible implementation, the rotary drive mechanism includes drive I, drive II, a worm and a worm wheel, wherein the two ends of the worm are respectively connected to drive I and drive II mounted on the fixed seat, the worm wheel is fixed on the rotary extrusion die, and the worm wheel is engaged with the worm, and drive I and drive II synchronously drive the worm to rotate, thereby driving the rotary extrusion die to rotate through the worm wheel.

[0016] In one possible implementation, there are four groups of rotary drive mechanisms, which are symmetrically arranged in pairs at both ends of the rotary extrusion die.

[0017] Another aspect of the present invention provides a composite extrusion method for strengthening and toughening a metal material using the above-mentioned device, comprising the following steps:

[0018] Step S1: Position initialization: the rotary extrusion rod, the piston end extrusion rod, and the inlet and outlet extrusion rods are extended to an initial position closed with the middle extrusion cavity;

[0019] The ejector piston in the piston-side extrusion die moves to an initial position away from the inlet and outlet sealing covers, opening the inlet and outlet sealing covers;

[0020] Step S2: placing the cylindrical metal blank into the middle extrusion cavity, installing the inlet and outlet sealing covers, and evacuating the extrusion cavity;

[0021] Step S3: the servo hydraulic pressure controls the ejection piston to press and extrude the metal blank, and the extrusion rod is synchronously rotated to draw and extrude the metal blank;

[0022] Step S4: the rotary extrusion die rotates, the rotary extrusion rod presses and extrude the metal blank, the inlet and outlet extrusion rods and the piston end extrusion rod draw and extrude the metal blank, and the metal grains in the metal blank are subjected to double-helix high-pressure torsional friction stirring to refine the grains;

[0023] Step S5: the rotary extrusion die rotates, the rotary extrusion rod draws and extrudes the metal, the inlet and outlet extrusion rods and the piston end extrusion rod press and extrude the metal blank, and the metal grains in the metal blank are subjected to double-helix high-pressure torsional friction stirring in reverse to refine the grains;

[0024] Step S6: Repeat steps S4 and S5 for a specified number of times;

[0025] Step S7: performing heat treatment on the metal using mold temperature control;

[0026] Step S8: The servo hydraulic pressure controls the ejection piston to move away from the metal blank, and the extrusion rod is synchronously rotated to press the metal blank; the inlet and outlet extrusion rods and the piston end side extrusion rod are closed with the middle extrusion cavity;

[0027] Step S9: removing the inlet and outlet sealing covers and ejecting the nanocrystalline cylindrical metal product through the ejection piston;

[0028] Step S10: performing macroscopic mechanical property testing and microscopic material science testing on the nanocrystalline cylindrical metal product.

[0029] The advantages and beneficial effects of the present invention are: the composite extrusion device for strengthening and toughening metal materials provided by the present invention realizes the rotational extrusion of the metal blank through the coordinated action of each mold and combined with the rotary drive mechanism, completes the internal grain refinement friction of the high-pressure torsion metal violent plastic deformation, and the extrusion cavity gradient changes throughout the entire process, which can adjust the stirring friction state of coarse and fine grains of metal grains, improve the plastic deformation ability of the blank, avoid metal cracking, improve the working efficiency of the mold and the mechanical properties of the product, and has good grain uniformity and high refinement efficiency. The relationship between the internal grain refinement friction of the microscopic high-pressure torsion metal violent plastic deformation and the macroscopic extrusion device operation process can be studied to obtain the process parameters for optimizing the extrusion efficiency.

[0030] This invention achieves spatial multi-spiral friction stirring of metal grains through high-pressure torsional extrusion of metal blanks, effectively refining the grains and improving the material's strength and plasticity. Furthermore, the device is equipped with a variety of auxiliary equipment, such as ultrasonic vibrators, process temperature control modules, and electric field auxiliary equipment, to further optimize the grain refinement effect.

[0031] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 This is an axonometric diagram of a composite extrusion device for strengthening and toughening metal materials according to the present invention;

[0035] Figure 2 A cross-sectional view of a composite extrusion device for strengthening and toughening metal materials according to the present invention;

[0036] Figure 3 for Figure 2 A partial enlarged view of the middle A;

[0037] Figure 4 for Figure 2 A partial enlarged view of point B in the middle;

[0038] Figure 5 Schematic diagram of the installation of the rotary drive mechanism of the present invention;

[0039] Figure 6This is an axonometric view of the rotary extrusion die of the present invention;

[0040] Figure 7 This is an axonometric view of the extrusion die on the feed and discharge sides of the present invention;

[0041] Figure 8 This is an axonometric view of the piston-side extrusion die of the present invention;

[0042] Figure 9 This is an axonometric view of the inlet and outlet sealing covers of the present invention;

[0043] Figure 10 This is a schematic diagram of the extrusion principle of a composite extrusion device for strengthening and toughening metal materials according to the present invention.

[0044] In the figure: 1. fixing seat; 101. base; 102. column; 2. ejector piston; 3. rotary extrusion die; 301. rotary extrusion middle cavity; 302. rotary extrusion side cavity; 4. rotary drive mechanism; 401. drive I; 402. drive II; 403. worm; 404. worm gear; 5. inlet and outlet side extrusion die; 501. inlet and outlet side extrusion middle cavity; 502. inlet and outlet side extrusion side cavity; 6. sealing element; 7. rotary extrusion rod; 701. rotary extrusion rod a; 702. rotary extrusion rod b; 8. inlet and outlet end extrusion rod; 801. inlet and outlet end extrusion rod a; 802. inlet and outlet end extrusion rod b; 9. piston end side extrusion rod; 901. piston end side extrusion rod a; 902. piston end side extrusion rod b; 1 0. Inlet and outlet sealing covers; 1001. Curved surface; 11. Middle extrusion chamber; 12. Inlet and outlet radial extrusion chamber; 13. Piston end radial extrusion chamber; 14. Rotating radial extrusion chamber; 15. Piston hydraulic chamber; 16. Bolt; 17. Hydraulic drive chamber for the inlet and outlet extrusion rod; 18. Hydraulic drive chamber for the rotary extrusion rod; 19. Hydraulic drive chamber for the piston side extrusion rod; 20. Grain extrusion space trajectory A; 21. Grain extrusion space trajectory B; 22. Grain extrusion space trajectory C; 23. Grain extrusion space trajectory D; 24. Piston side extrusion die; 2401. Piston side extrusion middle chamber; 2402. Piston side extrusion side chamber; 25. Spatial extrusion curved surface; 27. Extrusion eccentric rod; 28. Extrusion head; 29. ​​Piston sealing cover. DETAILED DESCRIPTION

[0045] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0046] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0047] See also Figures 1 to 10 As shown, the present invention provides a composite extrusion device for strengthening and toughening metal materials, including a fixed seat 1 and a rotary extrusion die 3, an inlet and outlet side extrusion die 5, a piston side extrusion die 24 and a rotary drive mechanism 4 arranged on the fixed seat 1, wherein the inlet and outlet side extrusion die 5, the rotary extrusion die 3 and the piston side extrusion die 24 are coaxially connected in sequence, and the rotary extrusion die 3 can rotate relative to the inlet and outlet side extrusion die 5 and the piston side extrusion die 24, and the interior of the inlet and outlet side extrusion die 5, the rotary extrusion die 3 and the piston side extrusion die 24 forms a closed extrusion cavity, the piston side extrusion die 24 provides extrusion power, and the rotary drive mechanism 4 is connected to the rotary extrusion die 3, and the rotary drive mechanism 4 is used to drive the rotary extrusion die 3 to rotate, thereby realizing rotary extrusion of the metal blank in the extrusion cavity.

[0048] See also Figure 1 As shown, in the embodiment of the present invention, the fixed base 1 includes a base 101 and a column 102 mounted on the base 101. The base 101 is insulated and fixed to the ground. The feed and discharge side extrusion die 5 and the piston side extrusion die 24 are mounted on the base 101, and the rotary drive mechanism 4 is mounted on the column 102.

[0049] See also Figure 2 、 Figures 6 to 10As shown, in the embodiment of the present invention, the rotary extrusion die 3 includes a rotary extrusion center cavity 301 and at least one rotary extrusion side cavity 302 disposed on the side of the rotary extrusion center cavity 301. The rotary extrusion side cavity 302 is provided with a servo-hydraulic-controlled rotary extrusion rod 7. The piston-side extrusion die 24 includes a piston-side extrusion center cavity 2401 and at least one piston-side extrusion side cavity 2402 disposed on the side of the piston-side extrusion center cavity 2401. The piston-side extrusion side cavity 2402 is provided with a servo-hydraulic-controlled piston end-side extrusion rod 9. The piston-side extrusion center cavity 2401 is provided with a servo-hydraulic-controlled ejector piston 2. The side of the ejector piston 2 facing away from the extrusion cavity is a piston hydraulic chamber 15, which is sealed by a piston sealing cover 29. The piston sealing cover 29 is connected to the end of the piston-side extrusion die 24 via bolts 16. The axial movement of the ejector piston 2 is controlled by the hydraulic pressure within the piston hydraulic chamber 15. The feed and discharge extrusion die 5 comprises a central extrusion chamber 501 and at least one side extrusion chamber 502 positioned to the side of the central extrusion chamber 501. A servo-hydraulic-controlled inlet and outlet extrusion rod 8 is located within the side extrusion chamber 502. The ends of the central extrusion chamber 501 are provided with inlet and outlet ports, which are sealed by inlet and outlet sealing caps 10. The piston-side extrusion chamber 2401, the rotary extrusion chamber 301, and the central extrusion chamber 501 are of equal diameter and interconnected to form a central extrusion chamber 11. The volume of the central extrusion chamber 11 changes due to the movement of the ejection piston 2.

[0050] Furthermore, the rotary extrusion rod 7, the inlet and outlet extrusion rod 8, and the piston end extrusion rod 9 have the same structure, each including an extrusion eccentric rod 27 and an extrusion head 28 disposed at the end of the extrusion eccentric rod 27. The extrusion eccentric rod 27 is eccentrically disposed with the extrusion head 28, and the end surface of the extrusion head 28 is a spatial extrusion curved surface 25. Within the rotary extrusion side chamber 302, on either side of the extrusion head 28 of the rotary extrusion rod 7 are a rotary radial extrusion chamber 14 and a rotary extrusion rod hydraulic drive chamber 18; within the feed and discharge side extrusion side chamber 502, on either side of the extrusion head 28 of the inlet and outlet extrusion rod 8 are an inlet and outlet radial extrusion chamber 12 and a feed and discharge side extrusion rod hydraulic drive chamber 17; within the piston side extrusion side chamber 2402, on either side of the extrusion head 28 of the piston end extrusion rod 9 are a piston end radial extrusion chamber 13 and a piston side extrusion rod hydraulic drive chamber 19; the rotary radial extrusion chamber 14, the inlet and outlet radial extrusion chamber 12, and the piston end radial extrusion chamber 13 all vertically penetrate the middle extrusion chamber 11, forming an equal-diameter angular extrusion die. The rotary extrusion rod hydraulic drive chamber 18, the feed and discharge side extrusion rod hydraulic drive chamber 17 and the piston side extrusion rod hydraulic drive chamber 19 are respectively sealed by a sealing member 6, and the sealing member 6 forms a dynamic seal with each extrusion rod.

[0051] Specifically, the spatial extrusion curved surface 25 of the end face of the extrusion head 28 is a spatial intersection section of the extrusion side cavity and the middle extrusion cavity 11 , and the curved surface boundary of the spatial extrusion curved surface 25 is a spatial saddle line.

[0052] In this embodiment, two rotary extrusion side cavities 302 are symmetrically provided on the side of the rotary extrusion middle cavity 301, and rotary extrusion rods a701 and rotary extrusion rods b702 are respectively provided in the two rotary extrusion side cavities 302; two inlet and outlet side extrusion side cavities 502 are symmetrically provided on the side of the inlet and outlet side extrusion middle cavity 501, and inlet and outlet end extrusion rods a801 and inlet and outlet end extrusion rods b802 are respectively provided in the two inlet and outlet side extrusion side cavities 502; two piston side extrusion side cavities 2402 are provided on the side of the piston side extrusion middle cavity 2401, and piston end side extrusion rods a901 and piston end side extrusion rods b902 are respectively provided in the two piston side extrusion side cavities 2402, see Figure 9 shown.

[0053] See also Figure 2 and Figure 9 As shown, in this embodiment of the present invention, a sealing column protrudes axially from the center of the inner end surface of the inlet and outlet sealing cover 10. The end surface of the sealing column is a curved surface 1001. The sealing column extends axially to a position where the curved surface 1001 corresponds to the inlet and outlet extrusion cavity 502. The curved surface 1001 at the end of the inlet and outlet sealing cover 10 effectively prevents corner dead zones in the metal blank and improves the uniformity of grain refinement.

[0054] Furthermore, an ultrasonic vibrator is installed on the outside of the inlet and outlet sealing cover 10 to assist in grain refinement of the extruded metal blank. A process temperature control module for controlling the temperature of the extrusion process is provided on the outside of the rotary extrusion die 3; the inlet and outlet side extrusion die 5 and the piston side extrusion die 24 are connected to electrodes for realizing electric field assisted grain refinement during the extrusion process; and a shock-absorbing float is provided at the bottom of the fixed seat 1. Specifically, the process temperature control module includes a heating coil, a cooling water channel and a temperature sensor, etc., so as to realize process temperature control of the extrusion process. The rotary extrusion die 3 is preferably made of zirconia ceramic with good insulation performance. Therefore, by connecting electrodes to the piston side extrusion die 24 and the inlet and outlet side extrusion die 5, electric field assisted grain refinement during the extrusion process can be realized. Installing an ultrasonic vibrator on the outside of the inlet and outlet sealing cover 10 can assist in grain refinement of the extruded metal.

[0055] See also Figure 1 and Figure 5 As shown, in an embodiment of the present invention, the rotary drive mechanism 4 includes a drive I 401, a drive II 402, a worm 403 and a worm wheel 404, wherein both ends of the worm 403 are respectively connected to the drive I 401 and the drive II 402 mounted on the fixed seat 1, and the worm wheel 404 is fixed on the rotary extrusion cavity 301 of the rotary extrusion die 3, and the worm wheel 404 is meshed with the worm 403 to form a meshing relationship of worm and worm; the drive I 401 and the drive II 402 synchronously drive the worm 403 to rotate, thereby driving the rotary extrusion die 3 to rotate through the worm wheel 404.

[0056] In this embodiment, there are four sets of rotary drive mechanisms 4, which are symmetrically arranged in pairs at both ends of the rotary extrusion cavity 301 of the rotary extrusion die 3. Drive I 401 and drive II 402 are preferably servo hydraulic motors and planetary reducers.

[0057] Specifically, the metal blank to be extruded includes, but is not limited to, aluminum and aluminum alloys, copper and copper alloys, pure iron, carbon steel, nickel, and other metal alloys. In this embodiment, a cylindrical blank made of 6201 aluminum alloy is preferred. The extrusion pressure is 0-10 GPa, and the rotational speed of the rotary extrusion die 3 is 0-30 rpm.

[0058] The present invention provides a composite extrusion device for strengthening and toughening metal materials, and its implementation process is as follows: first, the position is initialized, a metal blank is placed in a middle extrusion chamber 11 and vacuumed; the servo hydraulics control each component to extrude the metal blank, the rotary extrusion die 3 rotates, the rotary extrusion rod 7 cooperates with the inlet and outlet ends and the piston end side extrusion rods, so that the grains in the metal blank undergo double-helix high-pressure torsional friction stirring and refinement, and the cycle is repeated a specified number of times; heat treatment is performed; the ejection piston 2 is moved away from the metal blank, the rotary extrusion rod 7 is extruded, and the other extrusion rods are closed; the inlet and outlet ends are sealed with a cover 10 to eject the finished product; and the finished product is inspected.

[0059] See also Figure 2 and Figure 10 As shown, the present invention provides a composite extrusion device for strengthening and toughening metal materials, and its working principle is:

[0060] First, the device includes the rotary extrusion rod a701, the inlet and outlet extrusion rod a801 and the piston end side extrusion rod a901 on one side as side A, and the other side as side B. The side A and side B of the side extrusion cavity form equal diameter angular extrusion deformation with the middle extrusion cavity 11.

[0061] Specifically, during the equal diameter angular extrusion deformation process, the cylindrical metal blank may not rotate, or the cylindrical metal blank may rotate alternately around its own axis by ±90°, or the cylindrical metal blank may rotate around its own axis by +90°, or the cylindrical metal blank may rotate around its own axis by +180°. The rotation angle is selected according to actual needs.

[0062] The following is an example of a single grain trajectory:

[0063] See also Figure 10As shown, the individual grain trajectories between the A and B sides of the rotating radial extrusion chamber 14 and the piston-end radial extrusion chamber 13 are grain extrusion spatial trajectory A20 and grain extrusion spatial trajectory B21, respectively. The individual grain trajectory path of grain extrusion spatial trajectory A20 passes through the A side of the rotating radial extrusion chamber 14, the middle extrusion chamber 11, and the A side of the piston-end radial extrusion chamber 13. Similarly, the individual grain trajectory path of grain extrusion spatial trajectory B21 passes through the B side of the rotating radial extrusion chamber 14, the middle extrusion chamber 11, and the B side of the piston-end radial extrusion chamber 13. Grain extrusion spatial trajectory A20 and grain extrusion spatial trajectory B21 are spatially wound in a double helix within the middle extrusion chamber 11 to form m groups.

[0064] The individual grain trajectories between the A and B sides of the rotating radial extrusion chamber 14 and the inlet / outlet radial extrusion chamber 12 are grain extrusion spatial trajectory C22 and grain extrusion spatial trajectory D23, respectively. The individual grain trajectory path of grain extrusion spatial trajectory C22 passes through the A side of the rotating radial extrusion chamber 14, the middle extrusion chamber 11, and the A side of the inlet / outlet radial extrusion chamber 12. The individual grain trajectory path of grain extrusion spatial trajectory D23 passes through the B side of the rotating radial extrusion chamber 14, the middle extrusion chamber 11, and the B side of the inlet / outlet radial extrusion chamber 12. The grain extrusion spatial trajectory C22 and the grain extrusion spatial trajectory D23 are spatially wound in a double helical arrangement, forming n groups within the middle extrusion chamber 11. Spatial stir friction is also generated between the m and n groups of double helical windings, achieving a spiral gradient, ultimately resulting in a nano-grained cylindrical metal product with refined grains.

[0065] See also Figure 3 As shown, during the extrusion process, the ejector piston 2 servo feeds until the end portion penetrates into the corner corresponding to the piston side extrusion side cavity 2402, and the extrusion space at the corner is gradually reduced, so that the friction state of the grains at the extrusion corner is gradually strengthened, which can effectively prevent the metal from cracking during the extrusion process.

[0066] See also Figure 4 As shown, during the extrusion process, the extrusion head 28 of the inlet and outlet extrusion rods 8 penetrates into the middle extrusion cavity 11 and gradually servo feeds, thereby changing the end space of the middle extrusion cavity 11, so that the friction state of the grains at the end of the middle extrusion cavity 11 is gradually strengthened, thereby improving the uniformity of metal grain refinement.

[0067] The present invention provides a composite extrusion device for strengthening and toughening metal materials. The device achieves high-pressure torsion metal violent plastic deformation and internal grain refinement friction through the coordinated action of the extrusion die on the feeding and discharging side, the rotary extrusion die and the piston side extrusion die. The extrusion cavity is gradient-changed throughout the entire process. Since the stirring friction state of coarse-grained and fine-grained metal grains can be adjusted, the plastic deformation ability of the blank is improved, thereby effectively avoiding metal cracking, improving the working efficiency of the die, and improving the mechanical properties of the product.

[0068] Based on the above design concept, another embodiment of the present invention provides a composite extrusion method for strengthening and toughening metal materials, which is implemented by a composite extrusion device for strengthening and toughening metal materials in the above embodiment. The method includes the following steps:

[0069] Step S1: Position initialization: the rotary extrusion rod 7, the piston end extrusion rod 9 and the inlet and outlet extrusion rod 8 are extended to the initial position closed with the middle extrusion cavity 11;

[0070] The ejector piston 2 in the piston-side extrusion die 24 moves to an initial position away from the inlet and outlet sealing cover 10, opening the inlet and outlet sealing cover 10;

[0071] Step S2: placing the cylindrical metal blank into the middle extrusion cavity 11, installing the inlet and outlet sealing covers 10, and evacuating the extrusion cavity;

[0072] Step S3: The servo hydraulic pressure controls the ejection piston 2 to press and extrude the metal blank, and the extrusion rod 7 is synchronously rotated to extract and extrude the metal blank;

[0073] Step S4: the rotary extrusion die 3 rotates, and the rotary extrusion rod 7 presses and extrudes the metal blank, that is, the rotary extrusion rod 7 moves radially toward the middle extrusion cavity 11; the inlet and outlet extrusion rods 8 and the piston end side extrusion rod 9 draw and extrude the metal blank, that is, the inlet and outlet extrusion rods 8 and the piston end side extrusion rod 9 move radially outward, and the metal grains in the metal blank are subjected to double-helix high-pressure torsional friction stirring to refine the grains;

[0074] Step S5: the rotary extrusion die 3 rotates, the rotary extrusion rod 7 extracts and extrudes the metal, the inlet and outlet extrusion rods 8 and the piston end extrusion rod 9 press and extrude the metal blank, and the metal grains in the metal blank are subjected to double-helix high-pressure torsional friction stirring in reverse to refine the grains;

[0075] Step S6: Repeat steps S4 and S5 for a specified number of times;

[0076] Step S7: performing heat treatment on the metal using mold temperature control;

[0077] Step S8: The servo hydraulic pressure controls the ejection piston 2 to move away from the metal blank, and the extrusion rod 7 is rotated synchronously to press the metal blank; the inlet and outlet extrusion rods 8 and the piston end side extrusion rod 9 are closed with the middle extrusion cavity 11;

[0078] Step S9: dismantling the inlet and outlet sealing covers 10 and ejecting the nanocrystalline cylindrical metal product through the ejection piston 2;

[0079] Step S10: performing macroscopic mechanical property testing and microscopic material science testing on the nanocrystalline cylindrical metal product.

[0080] Through the above process steps, many nano-grain cylindrical products with different extrusion processes can be made, which can characterize the friction of the internal grain refinement caused by the severe plastic deformation of the micro-high-pressure torsion metal, and the relationship with the macro-extrusion device operation process (including but not limited to extrusion size, pressure, speed, electric field, temperature field, ultrasonic and other gradient process parameters), thereby obtaining process parameters for optimizing extrusion efficiency.

[0081] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A composite extrusion device for strengthening and toughening metal materials, characterized in that: The invention comprises a fixed seat (1), a rotary extrusion die (3) arranged on the fixed seat (1), an inlet and outlet side extrusion die (5), a piston side extrusion die (24) and a rotary drive mechanism (4), wherein the inlet and outlet side extrusion die (5), the rotary extrusion die (3) and the piston side extrusion die (24) are coaxially connected in sequence, and the rotary extrusion die (3) can rotate, and the inlet and outlet side extrusion die (5), the rotary extrusion die (3) and the piston side extrusion die (24) form an extrusion cavity inside, and the piston side extrusion die (24) provides extrusion power, and the rotary drive mechanism (4) is connected to the rotary extrusion die (3), and the rotary drive mechanism (4) is used to drive the rotary extrusion die (3) to rotate, thereby realizing rotary extrusion of the metal blank in the extrusion cavity; The rotary extrusion die (3) comprises a rotary extrusion middle cavity (301) and at least one rotary extrusion side cavity (302) arranged on the side of the rotary extrusion middle cavity (301), and a servo hydraulically controlled rotary extrusion rod (7) is provided in the rotary extrusion side cavity (302); The piston side extrusion die (24) comprises a piston side extrusion middle cavity (2401) and at least one piston side extrusion side cavity (2402) arranged on the side of the piston side extrusion middle cavity (2401); a servo hydraulically controlled piston end side extrusion rod (9) is arranged in the piston side extrusion side cavity (2402); and a servo hydraulically controlled ejection piston (2) is arranged in the piston side extrusion middle cavity (2401); The inlet and outlet side extrusion die (5) comprises an inlet and outlet side extrusion middle cavity (501) and at least one inlet and outlet side extrusion side cavity (502) arranged on the side of the inlet and outlet side extrusion middle cavity (501), wherein a servo hydraulically controlled inlet and outlet end extrusion rod (8) is arranged in the inlet and outlet side extrusion side cavity (502); an inlet and outlet port is provided at the end of the inlet and outlet side extrusion middle cavity (501), and the inlet and outlet port is sealed by an inlet and outlet end sealing cover (10); The piston side extrusion middle cavity (2401), the rotary extrusion middle cavity (301), and the inlet and outlet side extrusion middle cavity (501) are of equal diameter and are interconnected to form a middle extrusion cavity (11).

2. The composite extrusion device for strengthening and toughening metal materials according to claim 1, characterized in that: The rotary extrusion rod (7), the inlet and outlet extrusion rod (8) and the piston end side extrusion rod (9) have the same structure, and all include an extrusion eccentric rod (27) and an extrusion head (28) arranged at the end of the extrusion eccentric rod (27). The extrusion eccentric rod (27) and the extrusion head (28) are eccentrically arranged, and the end surface of the extrusion head (28) is a spatial extrusion curved surface (25).

3. The composite extrusion device for strengthening and toughening metal materials according to claim 1, characterized in that: A sealing column protrudes axially from the center of the inner end face of the inlet and outlet sealing cover (10), and the end face of the sealing column is a curved surface (1001). The sealing column extends axially to a position where the curved surface (1001) at the end corresponds to the inlet and outlet side extrusion side cavity (502).

4. The composite extrusion device for strengthening and toughening metal materials according to claim 1, characterized in that: An ultrasonic vibrator for assisting the extruded metal blank in grain refinement is installed on the outer side of the inlet and outlet sealing cover (10).

5. The composite extrusion device for strengthening and toughening metal materials according to claim 1, characterized in that: A process temperature control module for controlling the temperature of the extrusion process is provided on the outer side of the rotary extrusion die (3); electrodes for achieving electric field-assisted grain refinement during the extrusion process are connected to the feed and discharge side extrusion die (5) and the piston side extrusion die (24); and a shock-absorbing floater is provided at the bottom of the fixing seat (1).

6. The composite extrusion device for strengthening and toughening metal materials according to claim 1, characterized in that: The rotary drive mechanism (4) includes a drive I (401), a drive II (402), a worm (403) and a worm wheel (404), wherein the two ends of the worm (403) are respectively connected to the drive I (401) and the drive II (402) mounted on the fixed seat (1), the worm wheel (404) is fixed on the rotary extrusion die (3), and the worm wheel (404) is engaged with the worm (403), and the drive I (401) and the drive II (402) synchronously drive the worm (403) to rotate, thereby driving the rotary extrusion die (3) to rotate through the worm wheel (404).

7. The composite extrusion device for strengthening and toughening metal materials according to claim 6, characterized in that: The rotary drive mechanisms (4) are four groups, and are symmetrically arranged in pairs at both ends of the rotary extrusion die (3).

8. A composite extrusion method for strengthening and toughening metal materials using the device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step S1: Position initialization, the rotary extrusion rod (7), the piston end extrusion rod (9) and the inlet and outlet extrusion rod (8) are extended to an initial position closed with the middle extrusion chamber (11); The ejection piston (2) in the piston-side extrusion die (24) moves to an initial position away from the inlet and outlet sealing cover (10), thereby opening the inlet and outlet sealing cover (10); Step S2: placing the cylindrical metal blank into the middle extrusion cavity (11), installing the inlet and outlet sealing covers (10), and evacuating the extrusion cavity; Step S3: the servo hydraulic pressure controls the ejection piston (2) to press and extrude the metal blank, and the synchronous rotating extrusion rod (7) to extract and extrude the metal blank; Step S4: the rotary extrusion die (3) rotates, the rotary extrusion rod (7) presses and extrude the metal blank, the inlet and outlet extrusion rods (8) and the piston end extrusion rod (9) draw and extrude the metal blank, and the metal grains in the metal blank are subjected to double-helix high-pressure torsional friction stirring to refine the grains; Step S5: the rotary extrusion die (3) rotates, the rotary extrusion rod (7) draws and extrudes the metal, the inlet and outlet extrusion rods (8) and the piston end extrusion rod (9) press and extrude the metal blank, and the metal grains in the metal blank are subjected to double-helix high-pressure torsional friction stirring in reverse to refine the grains; Step S6: Repeat steps S4 and S5 for a specified number of times; Step S7: performing heat treatment on the metal using mold temperature control; Step S8: The servo hydraulic pressure controls the ejection piston (2) to move away from the metal blank, and the extrusion rod (7) is rotated synchronously to press and extrude the metal blank; the inlet and outlet extrusion rods (8) and the piston end side extrusion rod (9) are closed with the middle extrusion chamber (11); Step S9: disassembling the inlet and outlet sealing covers (10) and ejecting the nanocrystalline cylindrical metal product through the ejection piston (2); Step S10: performing macroscopic mechanical property testing and microscopic material science testing on the nanocrystalline cylindrical metal product.

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